#help-with-robotics

1 messages · Page 10 of 1

sterile silo
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Could someone please help point me in a direction of how to connect one of Adafruit's Dev boards, (any of the ones that have come in the last 9 AdaBox's as I already have them) with the RageBridge V2 (https://www.adafruit.com/product/3567) ?

RageBridge v2 from Equal Zero Designs

RageBridge 2 from Equals Zero Designs is a no-frills and robust dual-channel DC motor controller for robotic and vehicular drivetrain applications. It can supply 40 amps per side ...

primal shell
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That board has a lot of options, I think you can send it RC style PWM, serial commands, analog control, and possibly some others.

harsh hill
sterile silo
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Thanks @primal shell & @harsh hill But I'm hoping to get more simplified help in learning / figuring out how to get the OSPoC prototype working. The way my autistic brain is wired, I'm having an extremely hard time processing & learning how to correctly wire & program the RageBridge V2 with one of the Circuit Python capable Adafruit boards from the level of tutorials that they have out there.

harsh hill
sterile silo
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That'd be so appreciated @harsh hill . I have all the boards that came in AdaBox's 009 - 018, just let me know which one you think would be the most effective, lol, or just pick one that you prefer.

harsh hill
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Do you have any other requirements like wifi, Bluetooth, etc? And do you prefer circuitpython or arduino?

sterile silo
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Bare, with me, I'm still writing to answer just putting some pics up.

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Na, I need to keep it simple, but ya Circuit Python please. Having it run on CP, & CP's user friendliness is actually going to be one of the main marketable points.
So the RageBridge V2, the Adafruit board, a joystick (I don't have the joystick on my white board any where yet) (I have one of the kind of joysticks out of an old power chair) (pics above), I was able to figure out how to get the RC function of the RBV2 (if I understand the RBV2 sheet right, I think I'll be able to have a switch to toggle from RC to Adafruit board control with the joystick), hence the pic of my messy desk. The white board pic is my rough mock up of what I've figured I need the setup to be like. Please feel free to change if you think something would be better another way.

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There we go @harsh hill , I hope that mess makes sense.

harsh hill
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@sterile silo after looking though all the boards in the past 9 adaboxes I think the circuit playground bluefruit will be best as I couldn’t see any feather boards. Connect the tx pin of the circuit playground to the rx pin of the motor board. The ch3 pin should be connected to ground for the motor board to accept serial commands.

sterile silo
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O' I forgot, I also have the feather that came in AdaBox 008, the robot AdaBox

harsh hill
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To control the board create a serial device with a speed of 19200. Sending 0x00 will shutdown the motor controller. A value between 0x01 and 0x7f will control the first motor with 0x80 to 0xff for the second motor. The values in the middle of those ranges, 0x40 and 0xc0, will stop each of the motors.

sterile silo
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& the ItsyBitsy that has Bluefruit

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Would either of these be better?

harsh hill
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Using the itsy bitsy or the circuit playground bluefruit comes down to personal preference, it shouldn’t make much of a difference other than size and number of pins. I would avoid the m0 boards as they are not as fast as the nrf52840.

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The circuit playground bluefruit also has some sensors built in which you may want to use

sterile silo
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So the little Itsy Bitsy is actually more capable then the much bigger feather?

harsh hill
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For the feather in the picture yes but there are feather boards that are much faster than that itsy bitsy

sterile silo
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Which of the feathers do you think would be the best choice?

harsh hill
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I doubt you will need higher speed than the boards you already have

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The samd52 m4 and stm32f4 boards will be faster but it shouldn’t be necessary.

sterile silo
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Keep in mind also, that which ever one is chosen is going to be used in production of the customer units.

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I wonder which ones have the chip availability given the current conditions

harsh hill
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If you care about more consistent availability the boards using the rp2040 could be a good choice, I heard the chips have better availability than the samd and stm32 chips. They are using a m0 core instead of an m4 but due to their high clockspeed they should be around the same speed unless you are doing floating point arithmetic.

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If this is a product I would avoid the circuit playground boards and go with a board with pin headers as I don’t trust the contacts on the circuit playground boards for long term use when deployed.

sterile silo
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My laymen understanding of what kind of program, wouldn't it basically just be movement of the joystick, triggers the connections to allow power to get to the relays, that then permit power to get sent to the motors, the signal from the joystick directs the motors to go the needed direction. I don't think the program needs any fanciness or certain algorithms would it? My thinking, I'd actually wondered if the needed program power chair program would be simple enough that it could probably be written with just CP block code.

harsh hill
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If all you need is joystick control the board choice shouldn’t matter much at all

sterile silo
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LMAO! U know whAt your right! I've been over thinking this so much! & going buggy & brain fried in the process.

harsh hill
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Normally when I am advising people on robotics they are looking more into the autonomous control where the board choice matters much more so I also over complicated it.

sterile silo
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Well,,, funny you should mention that...

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As part of my attention getting by attending the Rochester Maker Faire with my OSPoC prototype, I want to use one of my other power chair bases & make a full size Dalek to also have at my booth.

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Of course using the same open source hardware & software.

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But then down the road, I want to keep giving it more & more capabilities & autonomy would be pretty awesome too. :-D

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I'm already designing a special weapons modification for it. A big air cannon that the lower skirt opens & the cannon lifts into place.

harsh hill
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Nice, I hope it goes well

pine bramble
harsh hill
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The itsy bitsy boards do have lots of options

sterile silo
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Thanks. But getting back to the basic, could you please go back to how I connect the CPB, joystick & the RBV2? & possibly also how you get them to talk with each other?

harsh hill
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Although I think the fastest feather currently is the stm32f405 which will still be faster than any itsy bitsy

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Do you know if your joystick includes a voltage divider built in?

sterile silo
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To be honest, I have no clue. I wasn't able to pull up much of any kind of data about it. There are so very little electronics in it.

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That stm32f405 PID: 4382, looks pretty serious & capable!

harsh hill
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I recently got 6 of those boards for a project, very good but a couple of limitations with USB which made it much harder to use for my project.

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How many pins does the joystick have and are they labeled?

pine bramble
sterile silo
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8 pin & no labeling at all.

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Hmm, perhaps I should work on getting one with potentiometers? Might be more user friendly.

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Or would one with a voltage devider be better?

pine bramble
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A potentiometer can be used as a voltage divider, with the middle pin providing you the varying voltage.

harsh hill
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A voltage divider is used with potentiometers to allow the analog pins to measure the angle

pine bramble
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Note that a Raspberry Pi doesn't have a built-in analog to digital converter (ADC) so you'd need to add an accessory (there are many). Microcontrollers often have multiple pins that can be used as ADC inputs.

harsh hill
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The joystick may just have 4 actuators in it

sterile silo
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Could you possibly look at Amazon & suggest one?

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I' was trying to search, but I'm not sure what to search for.

harsh hill
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Take a look at this post on the arduino forum, I think they have the same joystick as you https://forum.arduino.cc/t/setting-reference-voltages-on-outputs/154538/3

Arduino Forum
Setting reference voltages on outputs

John Thanks so much for you input. It was extremely helpful and I was able to duplicate the outputs of the joystick for the most part. Still some idiosyncrasies created by the controller board that present a problem. Hopefully the attached will help in understanding. Rather than rely solely upon autonomous control, I thought it would be nice t...

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You should be able to connect the pins it says changes to your microcontroller and read the value on those pins to see where the joystick is.

sterile silo
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Wow! great find!

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Ok, but then I'm going to need a micro controller with a bunch more pins then aren't I?

harsh hill
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I think you will only need 4 pins plus power and ground

sterile silo
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So that rules the CPB out.

harsh hill
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So the itsy bitsy should have plenty

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When the pins go high they reach 3.8v which is higher than the itsy bitsy can support

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So instead power the joystick with 3.3v instead of 5v and all the pins should decrease in voltage to a safe level for the board

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Connect up ground to the joystick and an analog pin to each of the output pins of the joystick that changes.

worldly river
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I bought a 3 pack of i2c ADCs, but it was $14. The pico is what, $4 (before shipping of course)

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although I have something stored deep in the back of my memory telling me the pico's ADC may require an external reference for decent results?

harsh hill
sterile silo
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But if I'm only powering it with 3.3V, with it normally being powered with 5V, & V drops to 1.1V. If it's powered with only 3.3V will the drop down voltage be recognizable enough?

harsh hill
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If it’s in an analog input pin you should be able to measure whatever the voltage is provided it isn’t over 3.3v

sterile silo
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When the V drops, it'll only be .66V

harsh hill
sterile silo
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Ok, any suggestions which pin might b pin 1?

harsh hill
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Do you still have the device it came with?

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If you do you can use a multimeter

sterile silo
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Um, not sure.

harsh hill
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But I am guessing it will be the top left pin

sterile silo
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Na, the controller board didn't work, that's why I swiped the joystick off of it.

harsh hill
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You may still get power out of the pins if you are lucky

sterile silo
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The pin closest to the sticker right?

harsh hill
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Yes

worldly river
sterile silo
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@harsh hill Whats ur impression of CircuitBrains Deluxe - CircuitPython-compatible SAMD51 Module - by Null Byte Labs
PRODUCT ID: 4802

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Thinking of manufacturing options down the road

harsh hill
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If you want to make a custom pcb without having to worry about implementing all the required circuits for a samd51 then it seems like a good option.

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If you want to use it I would instead develop on a different samd51 board such as a m4 metro, m4 grand central, m4 feather or m4 itsy bitsy and switch to it later once you are ready for the custom pcb.

sterile silo
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good point

harsh hill
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It does seem a little expensive for what it is though but there aren’t really any other solutions out there like it.

sterile silo
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Gotcha. Are you still willing to do a wiring diagram of how to connect the Itsy Bitsy, joystick, & RBV2?

harsh hill
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If I get time today I will make one

sterile silo
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Great, when u get a chance, thank you so much. 🙂

pine bramble
harsh hill
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@sterile silo didn’t get time to draw the circuit diagram for you yet, sorry about the delay. I have been very busy but I will try to get to it when I can.

sterile silo
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No worries @harsh hill . I certainly understand being busy. When you get the chance, it'll be very much appreciated & helpful.

wraith flame
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Thanks so much @heavy snow. The info about the resistorless-QWIICs is gold. Found out about the M1 with Mu the hard way. Glad to know the latest beta fixes things. Cheers1

arctic lotus
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Not sure if this is the correct channel for this question, but basically I've got a semi-unknown stepper motor attached to a Dobot Conveyor Belt (https://www.dobot.cc/products/conveyor-belt-kit-overview.html), I purchased the Adafruit Stepper Hat for Raspberry Pi a while back, stripped the motor wires and attached them to M1/M2 (https://learn.adafruit.com/adafruit-dc-and-stepper-motor-hat-for-raspberry-pi) and I am using a 12V power supply. I am able to get the conveyor belt to move forward/backward but the motor makes this really loud and unpleasant grinding/vibrating/crunching noise, I have put the M1/M2 wires in all different combinations (A+/A-/B+/B-, etc.) and it always makes that sound.

Just today I purchased 2 DRV8871 drivers to try (https://www.adafruit.com/product/3190) thinking that because they are current limiting, that may solve my problem. But I'm not 100% sure.

Any one have any ideas or thoughts of other things I could try?

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Here's the specs on the stepper motor on the conveyor belt:

b192832a4b11d7e97bfc935b599dd4cac43ea8b7.png
primal shell
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Have you tried running the motor by itself (not attached to the conveyor)?

arctic lotus
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It's a totally enclosed system

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and I have no idea what the brand name of the motor is

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so I can't unattach it from the conveyor and try it on it's own unfortuantely

primal shell
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It shows a rated voltage of 3.25V, so 12V may be a bit much, but many stepper drivers are current regulated, which would avoid problems with voltage.

arctic lotus
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So maybe my inklings towards using the DRV8871 will help?

primal shell
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I suspect it's a mechanical problem of some sort, but don't know enough about it to speculate in any detail.

arctic lotus
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it's almost like the motor is internally fighting with itself

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I think I have a video of it somewhere

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changing the code to use microstepping lowers the volume of the grinding quite a bit

primal shell
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That almost sounds like a missing phase: I'd do a quick continuity test of the motor windings.

arctic lotus
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do you have a link or an example of how one would do that?

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i'm a motor noob

primal shell
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Do you have a multimeter?

arctic lotus
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yes

primal shell
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Set it to measure resistance, and measure the resistance between the motor wires. You should get be able to find two pairs of wires with non-infinite resistance between them: those will be the motor windings (assuming a 4-wire bipolar stepper motor)

arctic lotus
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sweet, i'll give it a go. thank you @primal shell !

sage marsh
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@fierce gyro could you pass this idea to Limor Fried or Phillip Torrone? This would be so great. These commandments are a very big list 1-,2-,.....432-,433-, 1034-... They are simple and they are complex, if you force your mind to remember yours many of yours parents commandments probabily will be very similar to my parents commandments. This in a robot would make a lot of sense, because it is so dense that a human can't really process then all at once, but a robot can.

worldly river
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Eudecio, how do you know that the commandments are consistent?

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with thousands of commandments, it would be difficult to make sure none of them contradicted each other

primal shell
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That's true, Gödel's Incompleteness Theorem might apply.

vagrant thunder
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Do your commandments subscribe to any particular ideology when it comes to morals and ethics? Forgive me if I suggest anything you would be offended by, but I'm a bit skeptical that such a set of essentially hard-coded rules can follow anything more than maybe deontology, and the quality of this concept of yours is only as strong as the commandments your parents wrote.

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I'd love to see your commandment-following robot exceed anything we've ever done as far as creating some form of basic general-AI, but it's pretty difficult to believe that your parents' commandments can singlehandedly resolve all the struggles and contradictions that plagued philosophers for the greater portion of our human history....

steel lintel
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He won't share the list of commandments, so we can't check for consistency

lone skiff
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Just translating arbitrary verbal commandments into robotic behavior is basically Turing-Test-complete AI to start with.

steel lintel
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I think you'd end up with the same result as Asimov's 3 laws of robotics -- you'd have the problem of needing to define all the concepts within the rules/laws/commandments so that the robot can understand them

sage marsh
lapis marten
sage marsh
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It is complex and deep when you write, trust me.

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People generally see a big picture of it.

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It is bigger on the inside.

steel lintel
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But the problem is that a robot isn't going to have an intuitive understanding of 'human' or 'harm' or any other concepts that humans just understand

sage marsh
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I'll start to study now. I have to go. Bye.

steel lintel
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Bai

lapis marten
# steel lintel But the problem is that a robot isn't going to have an intuitive understanding o...

My favorite Asimov short story is about a robot trapped at the base, when their human is away from base on a mission. The robot realizes that the human’s space suit is about to fail (the radio failed too), but also realized that if it tried to run the parts out to the human that it would die before it got there due to the extreme solar energy on Mars, violating the “don’t harm yourself” law (and leaving the base unattended, disobeying the first law) - the robot wrestles with the decision and ultimately decides to break the rules and go on a suicide mission to bring him the parts.

steel lintel
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I have a vague memory of that story

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But yeah, Asimov's laws only work if the robot already understands all the concepts they address

sage marsh
# worldly river with thousands of commandments, it would be difficult to make sure none of them ...

In fact, there are clear opposite commandments in my parents laws, but they occur very rarelly, like 0.001% of them ( or less ). I have other books to to help the commandments, the robot will have it to help him to obey. There are categories for different types of commandments ( it is not something like: related to healthy, or related to school. It is more the essence of the commandment). Besides if there is a bug in a parent commandment there are like, 1997x10^(19591972) others that corrects the mistake. Note: 1997x 10^(19591972) is 1997 followed by 19591972 zeros, like: 199700......

lone skiff
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(There are only something like 10^80 atoms in the universe, heh heh.)

proven lotus
steel lintel
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Still gotta teach the robot what health, school, and everything else is

sage marsh
lone skiff
sage marsh
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It can be kept for the next generations of the robot.

lone skiff
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I'm just saying that having trillions of rules is impractical to implement or to follow.

sage marsh
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And converge, not diverge.

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The commandments from 15 years ago, converges with the commandments from today.

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The rules from my first years converges with the rules today, that is why this robot is great

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and the code is going pretty good it is literally the best code I've ever seen in life and the best code I'll ever see in life (better will be the continuation of it).

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For sure.

steel lintel
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"more commandments than the stars in the whole of existence" is certainly hyperbolic... your life won't even have that many seconds from start to finish as there are in the Milky Way, let alone the known universe. If you lived 100 years, that would be 3,153,600,000 [just over 3 billion] seconds. There's about 100-400 billion stars in the Milky Way, and if there's about 100 billion on average in every galaxy, probably about a billion trillion stars in the known universe. So you couldn't even get there if you wrote one every second... But then there's still the problem of the robot not being able to understand

sage marsh
steel lintel
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But you, as a human, have an innate understanding of concepts that a robot has no basis for. Robots aren't children, you can't teach them like a human child

earnest totem
# sage marsh When I was a kid I just obeyed, I did not understand.

I would argue that you still had some level of understanding though in order to obey in the first place. Maybe some of these commandments would be beyond a child, like making sure you pay taxes or save money, but the basic ones that a child could obey still require some background level of understanding.

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Knowing that you shouldn't hurt other people would come from an understanding of knowing what pain feels like to yourself

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as an example

sage marsh
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The commandments are direct, straight. It just have to obey it.

steel lintel
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But it can't understand it to obey it

steel lintel
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That's a throwback, lol

sage marsh
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My idea isn't perfect or better than all other ideas.

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But for my eyes is clearly great.

lone skiff
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People are just saying that if you can build a robot to obey "Keep your room clean", you're already past the state of the art and will be a billionaire in no time. 😁

sage marsh
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There are more than 24 laws to obey.

steel lintel
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3, 300, 30 billion laws, you still have to program the context before it can obey. Teaching a robot what a "human" is vs. a "cat" is already hard

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Teaching a more abstract concept like "harm" is even harder

sage marsh
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The program is very simple really.

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And short.

steel lintel
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Well, if you can write a simple and short program to allow a robot to processes rules given in human terms, you're gonna be rich and win a lot of awards

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'cuz right now it can be troublesome to keep a robot from mistaking a lamp post for a person or a piece of paper with lines on it from a cat in some instances

sage marsh
steel lintel
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If you could do what you're implying, you could basically print money

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A robot that can just understand human rules and follow instructions with a simple program... That would be like, the Holy Grail of robotics/AI

sage marsh
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Think simple Doctor.

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Literally. I am not an expert, but if you start with easier laws that a robot can obey today, it obeys. It can be just like a Life Simulator(game) simple like this.

earnest totem
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What is an example of an easy law that this robot could obey today?

steel lintel
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Simple is logic operations, math

sage marsh
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Do not eat green fruit.

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Like this.

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Fruit that is green, still not good to eat.

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A robot do not eat. I know.

steel lintel
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But you need to define every component of that, it's not that simple. YOU have an enormous amount of data and understanding to process that -- you understand what "do" and "not" and "eat" and "green" and "fruit" means, as well as the combination of those things

earnest totem
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Already there is an edge case, green pears or green apples are good to eat, so now you need to be able to distinguish those types of fruits from others

sage marsh
steel lintel
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But how does the robot know what "green" is?

worldly river
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Well, if the rule is don't eat green fruit it may be possible to implement. Certainly the "green" part. Detecting a fruit may be more difficult.

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a visible light sensor

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and object detection

sage marsh
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I'll take a more simpler.

steel lintel
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Exactly, it's not as simple as telling the robot "don't eat green fruit". You have to teach it to see, and recognize objects, and color, as well as the concept of eating

worldly river
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I think you will run into problems where you either have to simply the rules so much they are not useful, or make the robot so complex it can't be programmed

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but I am excited to see what you come up with

sage marsh
steel lintel
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There's also issues of things that humans can't even agree on... Like the full classification of "fruit" and "vegetable"

worldly river
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I love the project, it seems like something out of a sci-fi novel

sage marsh
steel lintel
worldly river
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and I'm sure you'll learn a lot from doing it

sage marsh
steel lintel
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I mean... telling a robot not to lift heavy things isn't terribly difficult -- but there's a difference between programming a robot with IF [weight > 25kg] THEN [do nothing] and the robot having any real understanding of what heavy really means. But that's programming logic, not just giving a robot a rule

earnest totem
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I agree that you probably do have several commandments that are technically feasible with today's technology. I think what is confusing people are your earlier statements about there being thousands to billions of commandments, which is an unachievable scope for any project.

sage marsh
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Now think.

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Imagine the robot doing 25 laws simple like this.

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Then 50...

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And so on...

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And with a lot of details.

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Very small and precise details.

steel lintel
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Yeah, simple concepts, but you'd still never get into the tens of thousands of rules, and that isn't going to result in anything with any understanding or learning capability

sage marsh
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From the books.

steel lintel
sage marsh
steel lintel
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Billions of rules is just something you could never ever practically do, it's not possible. Not writing them yourself

sage marsh
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I do not know how to say: I was lying you can not write billions of lines in a 100 years old life.

steel lintel
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You mean you were being hyperbolic? Exaggerating?

sage marsh
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As we learn in school.

steel lintel
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I got in trouble for being hyperbolic in school, lol

worldly river
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it's rhetoric 🙂 which would probably be very hard to teach a robot

steel lintel
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I believe someone could believe anything

sage marsh
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I mean we learn hyperbole in school.

steel lintel
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I knew someone who thought that they had the ability to manipulate space-time by putting magnets on a wheel, making a coil around the wheel, and running power thru the coil to make a field and spinning the wheel with or against the magnetic field of the coil... And if they spun it fast enough they'd create a black hole. Where did they get this idea? I have zero idea, but they still whole-heartedly believed it...

worldly river
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Ha, I don't think the idea to program a robot to follow rules is so strange though

sage marsh
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I never saw something like this in my whole life.

worldly river
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I think many people have had the idea of encoding rules in a robot

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and producing the ultimate fairness or whatever

steel lintel
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Some people are nuts, and it can be hard to recognize when someone is being hyperbolic and when someone believes something outlandish

worldly river
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it does not usually seem to work, but I think it's a worthwhile project

sage marsh
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You can't believe you can write trillions of lines in some years. I am assuming everyone here knows this.

steel lintel
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Some people don't have a sufficient grasp of reality to actually understand that

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For any thing you know to be a fact, someone on this planet probably thinks you're a fool for believing that [even if 99.99999% of the rest of us think it's fact]

sage marsh
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I know how it is important to think about people with some disability, my father doesn't walk, he has a physical disability, so I know this pretty well.

sage marsh
steel lintel
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Oh gosh, it's late, I need sleep... night night

manic depot
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I hoped I could post at show and tell a robot which drives around, find and drives towards arucos. Works so far but the chasis has so many tolerances. Anyone knows a more reliable drivng plattform in such size ?

RobotControl.png
native cipher
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@manic depot how large a robot do you want?
I really like Pololu' Romi chassis (it is about 15 cm diameter). For larger bots, especially outdoor ones, I quite like TS100 tank chassis (you can see it on my userpic)
And then of course there is a very popular DonkeyCar platform which works somewhat differently (it uses real steering instead of differential drive)

manic depot
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@native cipher one same size and one big enough to move in a garden with a notebook as "Brain"

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TS100 looks great for that

native cipher
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I do not think TS100 is large enough for a notebook. But do you really need a notebook as brain? Wouldn't Raspberry Pi or Jetson Nano work instead?

manic depot
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Pi would work as Controller but I am a bit thick of the performance lack. Hmmm maybe I start first with the smaller version so ts100 like and maby pi again. Pi4 is a bit power demanding

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Just thoughts....not sure yet

native cipher
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The only thing that really needs high performance is neural nets/AI - but I'd expect Jetson Nano to be up to the task (unless you are doing something really complex)

primal shell
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You could always put a Coral into a Jetson Nano if you needed more neural net horsepower

manic depot
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doh jetson nano looks cheaper than I thought, maybe I try that

native cipher
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Certainly cheaper than a laptop 😉

steel lintel
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o.o

arctic lotus
# arctic lotus Ugh this video pains me

Ok so I tried ordering a current limiting stepper motor driver from Adafruit but UPS is horrible and long story short I don’t have them. What are your guys thoughts, am I quickly destroying the motor on this thing if I keep running it like this?

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(In reference to the video I replied to)

arctic lotus
# steel lintel o.o

Posted some stuff and realized the NN work @manic depot was doing might not have relevancy with the Edge Impulse tool - jumped the gun!

steel lintel
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Ahh, gotcha. I thought you got in trouble XD

arctic lotus
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Nope 😂 but we do support the Jetson Nano! So if any of y’all do find that Edge Impulse works for your use case feel free to DM me

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I’m mostly here for my stepper motor woes 😭😭😭

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UPS is killing me

steel lintel
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I wish I could help, but I have no idea what's causing that painful sound

arctic lotus
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I thinkkkkkkk it’s cuz the motor quickly draws too much current

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But it’s been 5 years since I took an actual electrical engineering course so no clue

steel lintel
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Schematics?

arctic lotus
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mostly want to know if I can write up a blog / create a video on this conveyor belt with it running this horribly for a bit longer without completely frying it, it’s a $600 device so feel bad

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@steel lintel one moment I’ll grab what I have

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I just have the data sheet I think

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And the schematics of the Adafruit Stepper Motor Hat i am using currently

steel lintel
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Just trying to figure out what exactly is involved XD

arctic lotus
steel lintel
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And it's hard to tell -- is one motor fighting another? Or is it like, going back and forth really fast? I'm not figuring out how the noise is coming to be

arctic lotus
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And this kit without the robot, I cut the wires on the conveyor belt stepper motor and plugged them into the Adafruit hat

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The noise does lessen when I use the “microstep” option from the Adafruit python library

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I have an application all ready to do cube object detection and color identification on the moving conveyor belt with a raspberry pi HQ camera. I just feel bad writing a tutorial and creating a video about this combo of hardware when it sounds like literal death

steel lintel
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Ah, ok, so it's literally just one stepper moving, right? Are you able to tell if anything might be interfering mechanically?

arctic lotus
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Not that I can tell

vagrant thunder
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I run steppers that are "rate at 3.3V" at 24V quite a lot, so I can tell you voltage should not be the issue.

arctic lotus
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Yeah I have 12V power attached to it

vagrant thunder
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Steppers are generally very noisy motors, but that grinding sound is not the sound I'd expect

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What driver are you using now?

steel lintel
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Yeah, that sounds bad

arctic lotus
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The Adafruit RPi Stepper Motor Hat

steel lintel
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Did it ever work with that HAT? Or did it do that from the get-go?

arctic lotus
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I ordered 2 DRV8871 drivers but UPS sucks

vagrant thunder
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Have you tried it on an unloaded stepper?

arctic lotus
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It does actually run and move the belt with the HAT

vagrant thunder
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Does it make the same sound without the belt and conveyor assembly?

arctic lotus
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it’s done this sound on all types of motor steps since the get go

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I can’t detach the belt / motor that I am aware of

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It’s a contained system designed to be used with the Dobot robot

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But I figured I could chop the connector and just use it as a normal stepper motor

vagrant thunder
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Do you have another stepper to experiment with?

steel lintel
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If the HAT does it with any motor, maybe it's a defective HAT?

arctic lotus
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I can order another stepper motor on its own and give that a go

steel lintel
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One time I had a stepper driver that would fail for too small a movement for... some reason

arctic lotus
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Just not sure how to get it to make larger movements

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It only makes really really small turns

steel lintel
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hmm

arctic lotus
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On all step type settings / frequencies / clock speeds / etc

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Thought I was about to fry it, and took a week break

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Now I’m back at it cuz I don’t want to lug this thing with me when I move lol

vagrant thunder
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Do you have any kind of acceleration curve, or are you just turning it on/off?

steel lintel
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How much can you see of the stepper? Can you find a model number? Wondering if there's something proprietary about it to make it only work with the intended hardware...

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Oh! Yeah! Some steppers need an acceleration curve or they'll get jumpy or weird!

arctic lotus
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Seems it’s a proprietary Chinese part according to the data sheet Dobot sent me

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Acceleration curve?

steel lintel
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Yeah, some steppers need to start slowly, and speed up on a curve, instead of linear [straight] acceleration

arctic lotus
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Can that be manipulated in code?

vagrant thunder
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Steppers don't handle large changes to rotational speed very well, as their torque drops dramatically when trying to move

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It can be, but it's probably easier to just have the code increase the speed in smaller intervals

arctic lotus
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At 3:50 in that video

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You can see/hear what the conveyor sounds like running normally

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Thru the RPi on the Dobot

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So something is incredibly wrong with mine. I’ll order some standalone steppers and different types of drivers, and also try the multimeter suggestions @primal shell gave me last week or so

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Thank y’all for your help!! @vagrant thunder @steel lintel

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@vagrant thunder I’ll try your speed suggestion too

steel lintel
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Ahh, so the Dobot has a Pi? Is it the same controller?

steel lintel
vagrant thunder
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How many pins does the stepper motor have?

arctic lotus
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@steel lintel it has a pi on it yes, honestly that’s a good question. I’ll ask on the Dobot forum what driver they use

vagrant thunder
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Or, wires coming out of it...

arctic lotus
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My original forum question ^

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It’s a self contained system, the connectors are all professional and no wires anywhere. Just connector spots labeled “M1” M2” etc. it’s a really nice device

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Just more difficult when you’re trying to Frankenstein it 😂

steel lintel
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If you can figure out exactly what stepper controller they use, and maybe even get the software, you can rule out a software and controller issue if it still happens

arctic lotus
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They use all of this custom software

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Quite annoying but makes sense

vagrant thunder
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I mean, I have two likely theories right now: 1) a phase imbalance, or 2) a loose mechanical coupling. Not sure which is easier to debug, though....

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When no power is applied to the motor, can you spin the belt and see if you can hear any weird noises from near the motor?

steel lintel
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I lean towards mechanical, on instinct... phase imbalance would make sense. Acceleration curve is still on the list

vagrant thunder
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These are usually extremely easy to identify with the right tools and access to the connections, but on a closed system, I can only offer hypotheses.

steel lintel
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Yeah, closed system hackery is hard to troubleshoot

arctic lotus
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I will see what info I can get out of the Dobot forum 👀

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Have y’all ever made a homemade conveyor belt?

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I just really liked how professional this one looked but it’s caused me more headache than expected

steel lintel
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I have, but I didn't use steppers

arctic lotus
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What did you use? DC?

arctic lotus
steel lintel
# arctic lotus What did you use? DC?

Yeah, straight DC motors. I didn't need high accuracy, so it was set up like an optical rotary encoder -- alternating holes along an edge, it counted how many holes went by to determine position

vagrant thunder
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Resistance is normal, you're technically generating current every time you turn those motors through the windings haha

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It's a two-phase motor, so there's not a whole lot of miswiring possible...

arctic lotus
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Ok sweet glad that seems normal then

worldly river
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Is there a big accuracy difference between steppers and DC when they are both using feedback and reasonably advanced controllers?

vagrant thunder
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The precision of the stepper motor is going to be significantly higher, but regarding accuracy, it'll be more a matter of application. If the scale of the motion requires very small step sizes, the stepper is still going to be more accurate; with feedback, the only remaining difference is step size.

steel lintel
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Yeah, DC motors are good for big sweeping movements, steppers are going to be better for small, precise movements. My conveyer belt with DC motors just needed to be kinda accurate

primal shell
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You can get superb accuracy from DC motors and encoders (inkjet printer manufacturers originally used steppers, but switched to cheaper DC motors with encoders). However, it's difficult to do properly (which is why it took many years for the inkjet manufacturers to switch).

fierce trellis
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does anyone know something about pullet? I'm having issues with it, and I really would appreciate some help.

native cipher
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@fierce trellisyou sure you mean pullet?

unknown.png
fierce trellis
sly sand
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Hi! I've set myself a goal to build a robot in 30 days. It's going to climb a palm tree. I've been playing with the Arduino Nano RP2040 Connect this weekend (I love that it has an accelerometer and gyroscope onboard), and I'm wondering if anyone could tell me why it might not work as the brains to my prototype robot? I'm very new to CircuitPython. I'm not even sure if I can react to a free fall in time. Thank you!

sharp saffron
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Biggest piece of advice is get a debugging setup

sly sand
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thanks 🙂

iron fable
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I've attended this as a guest a few times and its super fun. You all should create something fun and enter! Its in San Francisco. https://www.dnalounge.com/calendar/2021/11-14.html

DNA Lounge: Cocktail Robotics Grand Challenge, 14 Nov 2021 (Sun)

Do you like ROBOTS? And DRINKING? Experience incredible
robot bartenders serving you drinks, lovingly crafted with MAD
SCIENCE by the finest competitors in the art of robotics and
bartending. You probably won't get wet. Probably. Or disassembled.
Probably. Spectators and Victims: Admission includes two robot drink
chips to spend at any cock...

steel lintel
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Perfect for a cocktail-mixing bot!

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Too bad I'm on the wrong side of the country

wraith flame
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Haven't been able to find NeoPixel Strands in the fritizing library. Do folks just use NeoPixel strips?

spiral coyote
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has anyone ever worked with a portable lipo charger before?

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these ones?

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i'm trying to charge a 11.1v lipo with 3 cells, but whenever i tried to do so, it will always reset itself. No alarms, no warnings, it just goes back to the selection screen
does anyone know what's up?

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this problem doesn't happen with my other lipo batteries

primal shell
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It could be your power supply isn't up to the task

ruby gust
smoky zealot
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I am considering a LIDAR for my next project which will be a small robot for in house movements only. Any suggestions on a reasonably priced LIDAR?

lone skiff
storm ore
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I am trying to drive 3 4V DC motors using Metro+Adafruit motor shield v2. Can I plug 12 V AC, 1.2 Amp wall wart to Metro (or is 12 V DC the way to go) ? Or might it be preferable to split up the power supply for the Metro and Motorshield?

idle valve
vagrant thunder
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Metro boards accept up to 9V, last I checked.

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You don't need 12V for 3 motors, you need a ~4V supply that can handle the current draw the motors are going to require.

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I think the motor shield has a minimum of 4.5V though

idle valve
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You can always run it at ~80% throttle, though.

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hm

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Yeah, says "Can run motors on 4.5VDC to 13.5VDC"

storm ore
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Thank you!

torpid garnet
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How can i reduce the voltage in a circuit that uses AA batteries?? Trying to make a DC motor spin slowly

idle valve
torpid garnet
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yup! well, and an on off switch

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i bought this cuz i'm new to electronics and don't know what i'm doing

idle valve
torpid garnet
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uh oh is that sarcasm?

idle valve
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No, enthusiasm!

torpid garnet
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oh sick!!!

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hahaha

idle valve
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I genuinely love these sorts of kits since you can just. Do whatever with them

torpid garnet
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Yeah. Now i just need to know how to do stuff

idle valve
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So what's your goal with making the motor spin slower - Do you want it to spin slower at a set speed, or do you want to vary the speed?

torpid garnet
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How would i do either? Variable means using a potentiometer right?

idle valve
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For a set speed, you could figure out something with those gears it comes with. Generally this will get you better performance - A higher torque for the same amount of power, at the cost of RPM

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If you reduce the voltage, it'll spin slower, but also reduces the amount of power to it (For obvious reasons), and depending on the motor you'll reach a power setting where it won't spin because it can't get going.

torpid garnet
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ahhhhh Good to know

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with what i saw online i tried throwing 2 resistors on a circuit and it didn't do anything

idle valve
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I don't fully understand how resistors work, and there's several ways you could do it. A voltage divider is one of them, but putting them in-line has to have specific settings depending on power consumption and that's beyond what I've ever needed. Largely because there's other ways to do it

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And possibly a solderless breadboard so you can pop things in and out really easily. Super useful for testing things and the like

torpid garnet
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Sounds good. Appreciate the advice

idle valve
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Once you want to get into programmable stuff like microcontrollers, breadboards are super useful as well.

torpid garnet
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Gotcha

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Can't help but notice the potentiometers have 3 contact points

idle valve
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Yes!

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They have your voltage, your ground, and the "output"

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In most cases, the pot is read by a microcontroller or some other doodad, but for a simple thing like this, it's just fine.

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For those in particular, the voltage in/ground are the outer pins (It doesn't really matter which is which) and the output is the center pin.

torpid garnet
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ahhh so it completes a circuit and then bleeds out the energy through the output as you turn it?

idle valve
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It's effectively a variable resistor. I'm not 100% sure on the physics or such behind it

torpid garnet
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In my head ground is like the safety for household electronics. but for this is ground the wire returning to the batteries?

idle valve
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Unless I'm completely dropping the ball on if this is a good idea, here's how I would wire it:

Battery positive to one side of the potentiometer
Battery negative to the other side of the potentiometer, and also to one side of the motor
Middle pin of the potentiometer to the other pin of the motor

torpid garnet
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Seems good to me

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If i turn the potentiometer so that the motor is off, are the batteries still losing power?

idle valve
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maybe. But it shouldn't be a direct short.

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You can turn it to where the motor doesn't make any noise, but it still might be passing through the motor just a wee bit.

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I'm actually heading out for a bit now, so I'll be back later. Feel free to keep posting questions, though, there's plenty of knowledgeable people around. Most of them know more than me, too!

torpid garnet
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Thank you very much i appreciate the help

vagrant thunder
# torpid garnet If i turn the potentiometer so that the motor is off, are the batteries still lo...

Technically, the battery will never completely turn off in this configuration, so you should still include the power switch. The current will always flow from the positive end through the motor to ground, and adjusting the pot will limit the current that flows through the motor. At its lowest, the current flowing through the motor will not even be enough to turn the little spindle, but the resistance from the potentiometer will continue to draw current and consume battery.

torpid garnet
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Good to know thank you

pine bramble
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Generally it’s better to pulse width modulate (PWM) a motor rather than simply vary its voltage, as a DC motor doesn’t react to voltage changes anywhere near as consistently as via PWM, which is also more efficient and both hardware and programmatically simpler.

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I.e. you won’t get linear response with PWM but closer than a potentiometer.

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Also, with PWM when the motor controller is set to zero there will be no battery loss through the motors.

torpid garnet
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Nice. They look simple enough too

round bough
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Hi to community,
First of all I want to appreciate Adafurit for such incredible products and libraries, and a special thanks for Adafruit AHRS Kalman library, implementing the original NXP library is a nightmare. I have been working with IMUs for a long time, and I used Adafruit BNO055 and Adafruit LSM9DS1 and lots of other sensor boards in my previous projects. I think the BNO sensor is a masterpiece but as you know you don't have access to source code nor matrices, so there is no possibility to manipulate the output. Having manipulation limitations on BNO I decided to use LSM9DS1, Now that I'm using it with the Adafruit AHRS library, the results are outstanding. Comparing BNO and LSM9DS1 outputs, LSM is a little bit shaky and unstable, so I decided to make some adjustments in library definitions, for example various noise constants and filter frequency, I also tried different ODR and FS setting on sensor but it had no noticeable effect. So I decided to ask to community,
What exact setting should be set for sensor?
Which frequency should I run the filter?
What should I do rather than above ones to get perfect and smooth output like BNO?
I will be happy for any advice from another perspectives too.
And your more than welcome to ask relative questions.

Best Regards,
Mason

sly sand
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I can't answer but what do you mean by can't manipulate the output ? Like you don't know the noise function and you can't kalman filter it ? Otherwise BNO055 seems very interesting

round bough
idle grove
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Can I use a Xbox one controller to control a robot running Ubuntu wirelessly

lone skiff
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Yes, with appropriate hardware and software.

torpid garnet
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How do i know which way to read a resistor???

forest cipher
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Good question

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I’d say with a multimeter if you can get one

steel lintel
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The tolerance bars are always on the right

DigiKey-Color-Code-Calculator.jpg
torpid garnet
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But for the 5 band one on that example what if it was flipped around?

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red can still be read as a tolerance

steel lintel
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Hmm... Actually, I've never seen red for tolerance...

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Oh, yeah, bands 1-3 are bunched up on the one end

torpid garnet
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ahhh

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thank you

steel lintel
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No problem!

sly sand
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My university used to have a bunch of self-serve free resistances boxes. Had a lot of fun taking a couple and running away to see who was new in the dept 😄

steel lintel
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Lol

torpid garnet
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Anyone know a beginner project i should work on to learn electronics and soldering?? i'm completely new to it

steel lintel
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There are kits that can teach you both

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Like this https://www.amazon.com/Elenco-AmeriKit-Learn-Solder-Kit/dp/B0009Z3JJA/ref=asc_df_B0009Z3JJA/?tag=hyprod-20&linkCode=df0&hvadid=312062319564&hvpos=&hvnetw=g&hvrand=6301997630163353823&hvpone=&hvptwo=&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=9007313&hvtargid=pla-436819672068&psc=1&tag=&ref=&adgrpid=62847940260&hvpone=&hvptwo=&hvadid=312062319564&hvpos=&hvnetw=g&hvrand=6301997630163353823&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=9007313&hvtargid=pla-436819672068

Elenco AmeriKit Learn to Solder Kit

Elenco AmeriKit Learn to Solder Kit

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Oop, long link... But anyway, kits like that start going over electronic basics and are good soldering practice

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Although I would check you Adafruit YouTube channel for videos about electronics in general

round bough
pine bramble
round bough
pine bramble
round bough
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you can even use separate breakout boards for gyro acc and ma

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mag

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but you have to consider imu axis conventions

pine bramble
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Yes, understood. In your description of what you've been doing you mentioned the black box nature of the BNO055, and I was simply wondering if you've tried using a second, different, IMU in order to be able to compare the two, as a form of "fusion".

round bough
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sure I did

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I tried LSM9DS1

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MPU 9250

round bough
round bough
pine bramble
# round bough sure I did

To be clear, I don't mean comparing them as products on the bench, I mean comparing them live, as in the two running at the same time, with a summing/fusion algorithm.

round bough
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I tried all of them with different calibration, fusion , frequency and ....

pine bramble
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...then you must have by now come to some conclusions on what works for you?

On my robots I and many of the Dallas Personal Robotics Group (DPRG) seem to have settled on the BNO055 or BNO085, though others have been handy as well.

round bough
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and I think using lsm9ds1 which I have it on my arduino nano board is more logical

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the whole board costs about 30 usd

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Just a bno sensor costs more than that

pine bramble
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Well, I have about a dozen IMUs of various kinds that I've experimented with, and several BNO055s. The newer Stemma versions are cheaper now, US$20 or so, and I don't have a requirement for more than one per robot, and a robot costs easily $800-1000. So the IMU cost isn't really all that significant. But for smaller projects a BNO055 is probably overkill, especially if one isn't using all 9 DoF.

smoky zealot
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I was considering controlling 12 servos using Stemma motor driver boards. Are multi-channel Stemma driver boards available? Any suggestions?

pine bramble
# smoky zealot I was considering controlling 12 servos using Stemma motor driver boards. Are mu...

Stemma is just the connector, it's actually using I2C protocol, so the big question is how many servos are handled by a servo driver board and if the I2C address of the board can be modified (often by a solder jumper) to permit multiple boards. Adafruit has a number of servo controllers, one a 16 channel (i.e., 16 servo) board for the Raspberry Pi (among others): https://www.adafruit.com/product/2327

Adafruit 16-Channel PWM / Servo HAT for Raspberry Pi - Mini Kit

The Raspberry Pi is a wonderful little computer, but one thing it isn't very good at is controlling DC Servo Motors - these motors need very specific and repetitive timing pulses to set ...

smoky zealot
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Thanks @pine bramble for the clarification and suggestions

pine bramble
# smoky zealot Thanks <@828135237744984114> for the clarification and suggestions

You're very welcome. I'm just digging around on how to use interrupts with the Pimoroni IO Expander, their little 4051-powered Breakout Garden board. I'm using it as the main digital and analog connection between my "Integrated Front Sensor" (a bunch of analog and digital IO pins) and a single I2C connection. Basically, if you include power and ground, a four wire connection to the entire front array of sensors on my robot: 5 analog IRs, 3 pairs of lever switches for my bumper, and a pair of analog light sensors for the moth behaviour. That whole assembly can be moved between the KR01 and KD01 with just that single connector and two 5mm bolts. What I'm thinking is to add an additional wire to push an interrupt and callback onto one of the Pi's GPIO pins so the bumpers don't need to be polled.

smoky zealot
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I am looking at the BNO055 Stemma QT based product, I read about it’s capabilities to provide outputs such as absolute orientation (Euler vector and quaterian), acceleration vector and others, need to better understand what these are and how to use them in a robot control system. If anyone is aware of any reading resources, can you point me to them? Is this device better suited for quadcopters or can it also be used in ground based robot control systems?

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Are there any tutorial type resources for the above?

pine bramble
fresh crown
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👍
they have a useful PID controller discussion too

tardy isle
#

ok quick question, if I have a servos connected to a voltage regulator which is connected to a battery, and I wanted to power a raspberry pi off of the same battery, can I connect a UBEC to the voltage regulator to bring the voltage down even more?

primal shell
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Sure, but it's likely more efficient to connect the UBEC to the battery instead.

tardy isle
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ok thanks!

nimble root
#

Worth mentioning that servos are usually fairly tolerant of somewhat higher voltages. Tower specs their servo speeds at both 6V and 4.8V. Servos might not even need to be on regulated voltage, though it might make speed / distance more repeatable. It’s also nice if the servos stall and draw more than your regulator max but less than the battery pack max.

round bough
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Is there anyone helping me with these mystery numbers?

unknown.png
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its from adafruit nxp

pine bramble
abstract totem
# round bough Is there anyone helping me with these mystery numbers?

Without knowing where the source code came from, it looks like it's a collection of constants for the kalman filter. They help the filter understand the boundaries of what the sensor's values can actually mean--for example the noise needs to be modeled because every sensor has a certain level of noise. Including that into your calculation helps the filter understand that the imu isn't fluttering everywhere when the levels are close the the noise levels.

native cipher
#

long ago I decided that kalman filter is black magic, best left to professionals - I might use a library that has it, but I am not qualified to make any changes or fine-tune any parameters...

abstract totem
sly sand
#

Hey folks, I built this little robot arm kit, but my kit didn't come with the arduino shield with potentiometers. Can I use the arm using only the arduino? If so, any tips on how to do so?

20210901_185725.jpg
lone skiff
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Without potentiometers you wouldn't have a manual way to control it, but you could still script motions in code, for example.

sly sand
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Yeah that was what I was hoping to do

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I'm very noob though. I will have to look up how to wire this to the board

#

all the servos have these 3 pin connectors on them. I think I will need to use the cables I used for breadboards to connect it all up

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or use a breadboard beside the arm to make life easier

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since I would assume the potentiometer arduino shield was made for just plugging the servos in directly

idle valve
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@sly sand You'll need to supply a PWM signal to the servos, and also +5v and Ground. I wouldn't recommend pulling off of the Arduino's 5v though, it's not designed for that much current.

#

The Uno has... 6 PWM channels, though? So there should be enough to control the arm as long as you supply power to the servos

sly sand
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Ok! I watched a very helpful video just now. I will power using bench power supply and then one of those 6 PWN channels. Its alive!!

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(using servo tester hehe)

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DroneBot Workshop video on using servos was very helpful

idle valve
sly sand
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Oooh ok I'll check it out now, thanks!! 🙂

willow geyser
idle valve
willow geyser
#

when VCC = V+ = 3V the pwm signal and i2c is great. But when VCC = 3V and V+ = 5V the PWM signal seems 1.7V and i2c is not stable.

idle valve
#

Hm. The thing that immediately comes to mind is the Jetson Nano's 5v might have some. Funky stuff going on. Have you tried with an external 5v source?

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When I get on my PC I'll be able to look and see what sort of circuitry differences there are between chips, but that'll be a few minutes

willow geyser
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and Jetson should be able to source 2.5A from each 5V pin

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but I am not driving a servo, just need the 5v PWM for external controller

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And yes, thank you , i am patiently waiting for your results 🙂

idle valve
willow geyser
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i think you are right, i will try to get 5v before the jetson

willow geyser
idle valve
#

That's. Weird. I'm not familiar with the Jetson, so I can't exactly say what's going on with that

willow geyser
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it's the PCA i am sure, i am looking for the problem

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yes, VCC is connected to v+ maybe i shorted?

idle valve
#

that sounds possible

#

?

willow geyser
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Yes and I confirmed they were shorter somehow , trying different board now

idle valve
#

OK, so. The PWM output is always going to be what the chip itself is supplied with. There's no method for it to adjust this - No transistors, mosfets, etc, on this board. It's designed for servos, which have a ground, voltage in, and PWM input. And most hobby servos don't care too much about what voltage that PWM signal is going to be at.

#

That said, V+ should definitely be separate from VCC, and any connection is going to be a short somewhere.

#

What are you trying to use the board for?

willow geyser
#

Hey @idle valve v+ is not attached to VCC so I am able to use the 3v3 logic and a 5v output. However, I wonder if there is a grounding issue? Just using the dc supply to power the system and my scope looks like this

#

Doesn't seem normal to me, what could be issue?

primal shell
#

Looks like a ground loop: you can get that if the two power supplies are plugged into different outlets and their ground references aren't connected to each other.

willow geyser
#

Ahh, it is in series. I will check ground, thank you very much!

willow geyser
#

@primal shell am I missing something , not sure why this would he floating

#

or have a ground loop

primal shell
#

I don't see enough of your setup to say. Normally there's a logic supply and a motor supply.

willow geyser
#

I have 48V from supply, to a dc step-down to 5v for logic , to power jetson nano which powers the pca9685

#

The 48v powers the motors and controllers

#

But the scope is refecend to negative on the step down for Gnd ref, and pwm 0 for positive ref

primal shell
#

Is the step-down an isolated one?

willow geyser
#

@primal shell how can I tell if it is isolated ?

#

And what would that mean? Do I need to add another path to ground after the step down?

primal shell
#

It would mean the ground wire for the input isn't connected to the ground wire for the output. You could try connecting them.

willow geyser
#

@primal shell brilliant you fixed the problem 😀 thank you!

willow geyser
#

@primal shell sorry to bother you again, but seems like I ran into another issue. If I have connected the DC step down output negative to the input negative, then both logic and motor ground is connected and should be stable , I even connected Ground of jetson again to main ground, but this ground still floats?

primal shell
#

I'm still not clear on your overall setup. What are you measuring there?

willow geyser
#

Gnd ref is pca9685 gnd and v+

#

Also jetson gnd ref, and pca9685 vcc

#

Maybe I am chasing ghost in machine it goes from. Normal to crazy

#

More concerning, is why pwm signal is 3.4V and not 5v

sly sand
#

Someone in your house captured your screen and is photoshopping you

willow geyser
#

no, that is me

#

ok, this is my setup again.

#

48V - DC step down 5V -> USB C adapter -> Jetson Nano -> PCA9685 -> V+ (5V) VCC(3V3) , GND to GND, GND is common between the input to the Step down regulator to the output of the regulator. When I measure with my Oscope with the GND ref of the Regulator output Negative, the Scope is stable when measuring PWM out of PCA; when I use the GND on the PCA as ref to the PWM out of the PCA, the scope is not stable.

#

multimeter continuty says all gnd are common

#

but this won't drive my motor controller. 😦

sly sand
#

back of the envelope hand-drawn schematic was posted where ;)

willow geyser
#

got it figured out, bad motor!

#

replaced motor all works now 🙂

primal shell
#

I'm impressed the motor yielded a scope trace like that, but still, good job figuring it out!

willow geyser
#

To confirm, this statement means to place the resistor between the signal output and the hall sensor + ref (5v) ?

unknown.png
willow geyser
#

seems not needed, i scope proper signal without

primal shell
#

It sounds like the sensor has an "open collector" output (on some motors), and those would need a pull-up resistor to operate reliably. Some Hall sensors have a logic output and would not need a pull-up resistor.

cursive helm
#

I suspect they tell you to use the pull-up for a reason...As noted, it may not be reliable without it. It does say "The speed pulse output is OC" .

willow geyser
#

perhaps, need to run it through logic level converter to be useful, will test it shortly.

primal shell
#

An advantage to open collector outputs is that you can often pull them up to whatever logic level you need, so you don't need a level shifter.

willow geyser
#

It is a 5V pulse signal

primal shell
#

If it's open collector, it would be whatever level the resistor pulls it up to.

willow geyser
#

why do i get 5v signal with no resistor?

primal shell
#

That I do not know.

desert orchid
#

if the resistors there to handle electrical interference on your lines and it is occurring without it could be something to do with how the servo handles power that the resistor helps enough to prevent from occuring

#

idk what your systems like, but I have seen people with badly planned and positioned coils in their projects that jammed up the works as well, don't think its that at all XD just that it will definitely be the last thing you realize..

willow geyser
#

anyone know of a power sensor (voltage is priority) for 48V? the one on the adafruit site seems only for 36V.

primal shell
#

Do you just want to detect the presence of voltage or actually measure power or what?

willow geyser
#

voltage for battery level is requirement, other features are useful but not required.

primal shell
#

A resistive voltage divider might be sufficient in that case.

willow geyser
#

wish it was on breakout board 😉

primal shell
#

You want a voltage divider on a breakout board?

willow geyser
#

i found what I need from "other" company

willow geyser
#

hey smart people, please help me understand this.... I have 2 identical motors, identical motor controllers, identical wiring. One motor operates perfectly on PWM or manual potentiometer mode. The second motor operates normally on manual mode but on PWM mode has 1/2 the power and uses 2X the current (no load) as the first motor. Both PWM signals are on the PCA9685 breakout. The settings on the motor controllers seem the same. Any idea what I am missing? or should check?

vagrant thunder
#

Confirmed an issue on the motor? What kind of motor?

#

Have you switched the motor/controllers around?

willow geyser
#

bldc motors

#

it's a new motor

#

i will swap controllers one moment

primal shell
#

I haven't tried using PWM on BLDC motors, that's more for DC and stepper motors in my experience.

willow geyser
#

the motor controller accepts PWM signal

#

swapping motor controllers shows that one motor is still normal both methods , and the other motor is not working as expected with 2x current draw and power loss

#

so i assume motor is issue, but do they go bad in storage?

#

or could hall wires be different?

#

not hall wires. hmm

vagrant thunder
#

Could be a stray capacitance in the faulty motor? That's all I can think of as far as PWM issues go...

willow geyser
#

i get the same issue with the motor even with the POT

vagrant thunder
#

Oh, I thought manual mode was the same

#

Hmmmm

#

Can you measure the resistance across the motor leads?

willow geyser
#

i can measure resistance into the controller? or there are 3 wires that go from controller to motor power?

#

red, yellow, black

vagrant thunder
#

Can you send me the part number for the motor in question?

#

I may have assumed all motors had a ground wire of some sort.

willow geyser
#

the multimeter seems to jump around for resistance on the black to red

willow geyser
#

riddle me this other question please....... why would PWM mode get less output then manual POT mode?

vagrant thunder
#

The controller looks like it's using an ADC to read the desired speed, so if it's something on the controller side, it could be a bad PWM-to-analog filter inside the controller. However, if the Potentiometer is exhibiting the same issues with the same motor in both modes, I would not be questioning the controller.

willow geyser
#

i replaced the motor

#

i was bad again, not sure why it goes bad

pine bramble
willow geyser
pine bramble
willow geyser
pine bramble
primal shell
#

Even BLDC?

willow geyser
pine bramble
willow geyser
#

It is the same

pine bramble
# willow geyser It is the same

Then that would suggest it's not a problem with an individual motor but an artifact of one rotating clockwise, the other counter-clockwise.

willow geyser
pine bramble
# willow geyser 💯 agree

This is one good reason to run with closed-loop control (using motor encoders and a PID controller), so that one can precisely set the velocity of each motor, otherwise it's impossible to drive in a straight line (or know how far the robot has gone).

willow geyser
pine bramble
#

By quality do you mean motor speed vs energy input? Wouldn't closed-loop control solve that by automatically increasing or decreasing the PWM of the motors so they were operating as per target velocity?

willow geyser
#

Stops working

pine bramble
willow geyser
pine bramble
#

Have they operated okay in the past? Or is this your first try using them? In other words, can you rule out a problem with the motors themselves and assume it's the controllers? It sounds like the problem is only in the counter direction, which suggests either a problem with the motor controller or in the way you're using the software to control them.

In any case, I'm off to bed (late here). Good luck!

willow geyser
#

Wonder if I switch the polarity of the bldc and hall sensor maybe that will fix it?

primal shell
#

It could be a phasing problem, I'm unsure what you mean by polarity here: the hall sensors are unipolar, and the motor windings are in a delta configuration. However, you could try swapping two of the motor drive wires.

willow geyser
supple moon
#

I don’t understand why a motor running in reverse would perform differently. Other than a technical explanation, my experience in first robotics has been that they run the same.

finite yew
#

Hi all. I think there may be something fundamental I'm missing here. I'm trying to drive a 5-6V medium solenoid, specifically https://www.adafruit.com/product/3992.

The idea was to drive it with an H bridge IC, powered via 5V from the USB pin of a feather, with the 5V input coming from a powerboost (to boost the lipo up to 5.2ishV. I have been able to drive it by hand for a fraction of a second by hooking it up directly to the power, but no luck when using the hbridge.

Here is a simple drawing of my circuit

#

I have verified that putting in a led between OA and OB of the hbridge does light up when I go to trigger it.

#

does anyone have any ideas? the trigger code is only pulsing IA for a very short amount of time since I know the solenoid takes a lot of current (And I only need it to kick on/off anyway, I don't need to hold position)

pine bramble
supple moon
pine bramble
#

Brushed DC motors have different physical characteristics in each direction. You may not have noticed it or perhaps the motors you were using didn’t differ below the threshold that other factors masked them.

#

PID controllers would entirely eliminate the problem.

primal shell
finite yew
#

IA is connected to D9, and I'm output-ing HIGH from D9 when I want to activate the solenoid. I am not driving IB though, I didn't think I needed to since It's just a solenoid and direction shouldn't matter?

#

I've also tried wiring OA to 1 wire of the solenoid, with the other solenoid wire to ground. (instead of using both OA and OB). The product page for this H bridge said I could drive 2 solenoids, so I assume to do that one would be on OA and the other on OB. I only have 1, though.

vagrant thunder
finite yew
# vagrant thunder Is your hbridge ic rated for the current the solenoid is trying to draw?

It should be, is only supposed to draw 0.8A at 5V. I think i figured out the "why" but now I'm not sure on the best fix. It seems the voltage output from the h bridge is only about 4.6V, not enough to activate. This is further proven by it being able to hold position if I manually move it while activating the h bridge, and de actuates once i remove power to it.

#

So it seems to work if I manually pulse it 5V by touching the wire to the 5V out of the power boost. So I need another way to control it that doesn't drop as much voltage? I've seen MOSFETs and diodes being used, but i thought and h bridge is pretty much the same thing, but in IC form. Or somehow boost the power more?

primal shell
#

An H bridge is only needed if you want bidirectional motion: most solenoids just pull one way and are either passive or have a spring return the other way. To just pull one way, a simple transistor works well.

#

Note that you'll also want a protection diode, as with any inductive load.

finite yew
#

Yea, I just thought it would be a more convenient package.

vagrant thunder
#

Just to be sure, you're using a powerboost 1000?

finite yew
#

Yea

vagrant thunder
#

Okay, then it's most likely the voltage drop through the bridge chip.

#

The bridge seems to output around 7.6 volts when supplied with 9V. I anticipate your circuit is probably also experiencing a similar drop of either 1 or 1.4V?

#

You may have to use a higher supply voltage to utilize this driver.

finite yew
#

Ah, thanks. I will look into that

#

Does it have built in diode protection?

vagrant thunder
#

No.

#

Actually, wait a minute

#

Yeah, you'll probably need your own protection diode. I don't think the H-bridge had diode protection either, though....

finite yew
#

Oh, I thought it would have.

#

The hbridge I mean

vagrant thunder
#

Uhhhh, @primal shell Protection diodes are routed parallel and reverse direction of the device in question?

primal shell
#

That's a usual configuration, but there are other possibilities.

smoky zealot
#

https://www.adafruit.com/product/4010 - Before I use the RPLIDAR A1M8 with an embedded device, I wanted to check it out with the RoboStudio on Windows10. I am able to recognize the device on the COM port as seen in Windows Device Manager, but am not able to connect it to RoboStudio application. Can anyone help with suggestions or pointers?

Slamtec RPLIDAR A1 - 360 Laser Range Scanner

Is your favorite robot currently in a mid-life crisis? Does it need a new purpose or perhaps, direction?  Well now you can find your way with the affordable and easy to use Slamtec ...

smoky zealot
#

I was able to figure this out. By using framegrabber from the SDK rather than RoboStudio, it worked

cinder gust
#

anyone active here that can teach me something? I just started and Im having problems with a capacitor lol

lone skiff
fresh crown
#

not knowing whats up, I can randomly say that I know a few capacitor types hate getting negative voltage

pine bramble
#

not knowing what's up, I'm not sure a capacitor issue has anything to do with robotics... 🤔

fresh crown
#

I have one of those cheapo pivoting ip camera thingies that seems to cause an undervolt during early start (and thus a startup loop), I'm guessing due to the motors. once I rule out the powersupply as a problem I'll look loosely in the direction of capacitors

pine bramble
#

Or isolate the power supplies for your non-computer bits.

fresh crown
#

eh, it is a product I have not opened yet, the part that undervolts is whatever onboard controller it has, I'll have to open it for more info, but as a function of laziness that may be a half year from now

primal shell
#

It's possible that a big capacitor might not help: if the power supply is shutting down due to overcurrent, it might do the same thing charging the capacitor. It's worth a try, however. If it has trouble with that, you can wait for it to charge the capacitor a pulse at a time, or add a soft start circuit that charges the capacitor through a current limiting resistor.

indigo echo
#

I have a Adafruit Feather 32u4 Bluefruit LE with a DC Motor + Stepper FeatherWing. A couple of weeks ago i got the motor and stepper working and still trying to figure out how to connect to the bluefruit. I connected to the feather today and got the following error message.
processing.app.debug.runnerexception
at cc.arduino.packages.uploaders.SerialUploader.uploadUsingPreferences(SerialUploader.java;152)
at cc.arduion.UploaderUtils.upload(UploaderUtile.java:77
And it goes on. Can anyone give me some suggestion on where to look to fix the problem.

primal shell
#

The first few lines tell where it's happening, the last few lines (hopefully) tell what is happening, which is likely the important bit.

indigo echo
primal shell
#

Possibly, it seems to think something else is using that port.

oak ingot
#

Hi folks, I need a little help selecting a motor driver. I'm planning a small 3-wheel car (running just 2 motors) and of course I'll use PWM to control the motor speed. I've narrowed it down to two Adafruit breakout boards with either the TB6612 or DRV8833 driver. I think either will work fine for my power needs, but the confusing bit is in the wiring for PWM... The TB6612 has dedicated PWM inputs for each H-bridge, whereas the DRV8833 does not and will take PWM as the input signal, which makes perfect sense to me (as far as my understanding of how the H-bridge works)... So can anybody explain why the TB6612 board has a separate input for PWM?

native cipher
#

tb6612 uses for every motor a pwm signal and two additional signals to set direction/braking; they are not pwm - they only indicate direction. It can be benefitial when you have plenty of digital pins but few pwm pins

#

but yes, I also find two pwm inputs like drv8833 uses more natural

oak ingot
#

Thanks @native cipher ! That makes sense, and it's good to know that it's just a design decision rather than a behavioral difference.

unreal sorrel
#

I have a project that requires two 35kg servos with an operation voltage of 7.4v, what is the best way to power these servos via like a wall outlet? It will always be connected to power and will need to run every night for probably 5 hours or so, I did something similar last year with smaller servos but was trying to power them directly from an arduino uno so they cut out pretty often and had to have a separate uno for each servo. Ideally I will be able to control both servos via one arduino and have them powered externally so I don't have to worry about it dropping out or anything. Just wondering what my best option is for power.

native cipher
#

(I haven't tried this particular one it is just to illustrate what I am talking about)

#

and split the power 3 ways, to Arduino and to each servo

pine bramble
vagrant thunder
native cipher
#

putting power through transistors? why?
you would do that for a DC motor, but servos have their own controlling circutiry inside - all they need is power and a separate controlling PWM signal
And for all servos I had seen, even if they operate at 7.4V, controlling PWM signal can be 5V

#

so I would just connect output of 7.4V power supply to servos Vcc and Gnd, and output of two PWM pins of arduino uno to the signal input of the servos.
You can choose a separate power source for uno, or use the same one (if it provides enough amperage); in all cases, you would need to connect ground of uno to ground of servos

unreal sorrel
#

thanks for all the replies, is there anyway i can figure out how much amperage i would need for the two servos and an uno?

vocal bear
#

what servos are you using?

unreal sorrel
#

last time i used 25 kg servos that i got on amazon but i think i need more torque as they sometimes couldn’t handle the load. so this time i’ll be using 35 kg servos (haven’t ordered them yet so if you have any recommendations i’d love to hear them). i guess the model of the one i’m leaning towards is DS3235.

modern pulsar
vocal bear
#

Uno should be negligible compared to the servos, unless you're talking about a battery system

native cipher
#

Of course, normal operating current is much lower, but to avoid problems with arduino when the servo is stalled, I'd suggest at least 5A supply

unreal sorrel
#

cool, so would the supply that you linked be sufficient then?

native cipher
#

should be, but if you can find one that gives you 6A or more, I'd suggest that. It is always good to have some reserves

spring cipher
#

Hi, I’m working feather sense. I want to know if my robot turned 90 degree properly. Idk which sensors on it I should be using. And also what strategy I should use

lone skiff
spring cipher
lone skiff
spring cipher
#

Can feather sense do this. It looks like it already have yaw

lone skiff
native cipher
spring cipher
#

Is there any for that?

#

Or I have to reproduce the algorithm

#

?

vocal bear
#

Probably have to reproduce the algorithm

spring cipher
#

Thanks!

native cipher
#

i am not sure if there are good implementations of sensor fusion in circuit python. Major problem is speed: these algorithms require a lot of floating point computation which must run with reasonably high frequency to get good result - and circuit python is significantly slower than C/C++.

pine bramble
native cipher
#

yes, but they add overhead. I am not a professional, but I have seen claims that depending on task, micropython can run slower than C on same hardware by factor of 10-50

#

in most cases it doesn't matter, but not in sensor fusion

vocal bear
#

My understanding is that uP/CP are indeed significantly slower on the same hardware. But they could always get the teensy that runs CP, it's blazing fast

#

Something like half a GHz?

native cipher
#

this thread started with discussion of sensor fusion on feather sense, which is based on nRF52840 - decent speed but no teensy

vocal bear
#

Yeah I guess if you're considering another board entirely why not just use a breakout that does the fusion.

native cipher
#

it does have floating point accelerator though

vocal bear
#

Esp since the teensy doesn't have an on board sensor like the feather sense

#

I wonder if writing a c module to do the fusion would help with speed

native cipher
#

so it might be possible to do sensor fusion in Circuit Python... i just haven't seen it done

vocal bear
#

How would you figure out the torque required to keep a load moving once it's brought up to speed? Would it be the torque such that sum(mom) = 0?

lone skiff
#

Once it's at speed, the theoretical torque required is nothing. But reality being as it is, the motor needs to counteract the friction in the system.

pine bramble
#

So in theory, so long as one had floating point support on the MCU there wouldn't necessarily have to be any performance hit at all.

vocal bear
lone skiff
vocal bear
#

I should have broken out what was in sum(mom) as I was thinking about bearing/other fractions

#

Thanks!

lone skiff
# vocal bear Thanks!

If there are people on your platform shifting around and moving their position, you'll also have a torque requirement to keep the speed constant versus their movement... the classic figure-skater-pulling-their-arms-in effect.

vocal bear
#

It turns out there won't be people on it!

#

So I have way fewer safety concerns

keen tulip
#

Hi! Do y'all know where to find a good SG90 servo datasheet?

primal shell
keen tulip
#

But I'm not quite sure how reliable that site is:D

vagrant thunder
keen tulip
#

Ok cool thanks!

#

I was getting real confused because the datasheet I found said 20ms = 50Hz

#

oops maybe I just converted ms to hz wronf

vagrant thunder
#

That is correct. 20ms = 0.02s = 1/50

#

Haha, I've done worse.

keen tulip
#

:D:D Ok cool thank you!

potent haven
#

I am looking to get a robot for picking and sorting with conveyor belts

#

Any recommendations?

primal shell
#

Heh, I'm building something like that, but I'm using Lego motors

lone skiff
potent haven
#

1-2k

wraith sail
pine bramble
primal shell
#

Those are great for prototyping. In a similar vein, 80/20 extrusion is also handy.

potent haven
#

I picked up a delta robot kit

#

Delta x

pine bramble
#

<@&327289013561982976> spam!

vocal bear
#

random question: How would you convert torque on a threaded member into axial force caused by the thread engagement?

#

Like say you had one of those special drivers that specifies its torque so you know the input

lone skiff
vocal bear
#

Ahh I knew I was forgetting something from shigley's

mortal dagger
#

If I've got 2 motors with slightly different outputs at the same voltage (batch variance), is the best way to keep them at the same output some kind of PID function or am I overthinking it?

pine bramble
# mortal dagger If I've got 2 motors with slightly different outputs at the same voltage (batch ...

On a typical robot with a motor on the left and a motor on the right side, to go forward one motor will be going clockwise, the other motor counter-clockwise. It's entirely typical of DC brushed motors to have a difference in performance in each direction, so it's entirely typical that such a robot will not run in a straight line. So having motor encoders and a PID controller is exactly how one fixes this problem. You're not overthinking the problem.

native cipher
#

indeed
But that requires motor encoders
Another option - if the motors are used for driving - is using an IMU to keep track of direction and use heading information from IMU as input for PID
that also works well

mortal dagger
#

I have encoders on my motors

native cipher
#

then PID is easiest
You can runs separate PID on each motor or single PID which takes difference of encoders as input and outputs correction

mortal dagger
#

The latter was what I was thinking

pine bramble
# native cipher then PID is easiest You can runs separate PID on each motor or single PID which ...

You can basically use a PID controller to regulate velocity, or a PID controller to regulate position. The latter you've described would be effectively used to provide a correction to the target velocity of two motor controllers, and could be used directly in that way. But since the motor controllers themselves (in that scenario) wouldn't be PID controlled, you wouldn't have the ability to encoder-regulate their velocities (i.e., you'd have steering but no velocity control). So (please correct me if I'm wrong), on a two motor robot it really makes sense to have either two (for independent velocity control of each motor) or three (for velocity and steering), but not so much only one.

native cipher
#

true. But in many cases it is not that essential: you do not care if your robot goes 50cm/s or 55cm/s as long as it goes straight.

pine bramble
#

Yes, agreed. I guess my real point is that you don't get something for nothing. So yes, you get a straight line with a steering PID but you don't get independent velocity control, or odometry. But with a pair of PID controllers you get independent velocity control, odometry, straight lines, or indeed, any trajectory you can describe mathematically. David Anderson of the DPRG recently demonstrated ballet-style pirouettes across the floor using a pair of PID controllers.

#

I'm using a pair of analog infrared sensors (aiming about 30 degrees from forward, to port and starboard) to provide a single differential value that I can apply as lambda functions to each of my PID controllers. This (as a single behaviour) causes the robot to swerve away from the perceived obstacle.

native cipher
#

what are lambda functions?

#

I mean, I know what it means in theoretical CS, but how do you use it with PID?

mortal dagger
#

Initially getting the thing going in a straight line is the first goal. I can deal with velocity later. I finally got my optointerrupters in and connected up to my board so I have all the hardware pieces of the puzzle.

#

Guess I should set it aside for the moment though, since there seems to be an RP2040-specific crash bug in CP regarding using countio and pwmio at the same time.

pine bramble
# native cipher what are lambda functions?

In Python they’re simply the passing of a function as an argument, so I’ve got a list container on my Motor class that can accept one or more lambdas that sequentially can modify the target velocity. I also commonly use them as sanity check limiters on values, etc.

#

So when I set the target velocity of the PID controller that value goes through any lambda filters before actually setting the PID’s actual target value.

spring cipher
#

@pine bramble I am also working on a PID controller for speed control of DC motor. I am also kind of stuck with it. So I am using DC motor, nrf5280, and feather wing dc motor controller. Problem is, when I start running the motor at certain speed, I can't change and set new speed since the PID system is running to keep the previous speed(rpm for say). In circuitpython we don't have multi-threading nor input-interrupt routine, so I can't find any solution.
Did anyone create a DC motor speed pid controller with circuitpython? Maybe using motoKit library in circuitpython?

golden dew
#

is PXFmini still avaialable?!?!?or did it get canceled?

turbid trail
# spring cipher <@!828135237744984114> I am also working on a PID controller for speed control o...

we have added preliminary asyncio support to CPy 7.1.0-beta.0, which is coming out tonight. async/await in general have been out for a while, so you could try writing a cooperative multitasking PID controller using asyncio or some other event-loop library. You could use soft interrupts by using countio to catch falling edges and then polling its results. I'm not sure that will be what you want, but thought I would let you know.

pine bramble
pine bramble
# spring cipher <@!828135237744984114> I am also working on a PID controller for speed control o...

It sounds like you could have the target velocity of your PID loop passed into the loop as a lambda, so that you can set what would be an "external" variable value and have it affect the "internal" of the loop. But I totally understand the issue with Python, and I've actually tried using Thread before I ended up with asyncio (for my overall system) and any kind of precision timing in a time-shared system (both Linux and Python) can get tricky.

#

As an example, I was using an MCU (TinyPICO) as an external 20Hz clock for my PID controller and motor controller loops, but was also loading it with another task that would sometimes grab too much of the MCU's processing time, and that would throw off the timing of the PID loop, which could cause all manner of problems, like massive ramp-up feedback loops or irregular oscillations, etc. The one thing about a PID loop is that its timing loop can't vary - at all.

primal shell
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It can, if the algorithm is written to adapt to timing variations. However, most algorithms aren't, and will fail as described if the timing varies.

pine bramble
# primal shell Excellent writeup here: http://brettbeauregard.com/blog/2011/04/improving-the-b...

I wrote my own PID controller (in Python) based on ideas gleaned from Brett Beauregard's article and others, but the problem is that if the underlying timing loop is not regular and the whole notion of time in the loop is distorted by not having a fixed clock, then yes, it is possible to write a PID controller but a great deal more difficult. I was never able to tune mine very well, and then if the clock varied the tuning itself would need to change as well, in the same way that one needs to re-tune if the dynamics of the robot changes (e.g., it picks up something heavy or alters its drive mechanics such as having any of its wheels no longer in contact with the ground).

In the weekly discussions of the Dallas Personal Robotics Group (DPRG) we kinda joke about the rabbit hole we regularly fall into as regards PID controllers...

inner siren
#

ADVICE HELP I'm newly retired & just getting into microcontrollers. I've done no robotics yet and it's too complicated to explain...but I need to buy some motors and bearings NOW for whatever may come in future projects. What type/size of motors and bearings are handy to just have around?

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Thank you so much

vocal bear
#

servos are always nice. Steppers are good too. Plain old brushed DC motors have applications

#

size and type is really going to depend on the project you're working on though, so without that info I can't give you super specific advice

#

happy retirement! This is a great place for learning something new

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this whole Discord is

#

I'd recommend checking out CircuitPython, it has some limits but it's a great way to learn programming. Make sure you get an M4 board or "better", I wouldn't bother with an M0 chip for any meaningful CP program

pine bramble
# inner siren ADVICE HELP I'm newly retired & just getting into microcontrollers. I've done ...

The choice of motors will depend entirely on the scale of the robots you might build. If you're fairly serious about robotics (i.e., you don't just want a remote-controlled toy), you'll probably want to choose motors that have Hall effect motor encoders either already attached or as an option. This is to permit you to precisely measure how far each motor has travelled, its velocity, and likewise perform odometry. This is absolutely necessary for autonomous navigation: if the robot can't travel in a straight line or tell where it is in 2D space it can't navigate, it just runs around avoiding obstacles (hopefully).

On the smaller end of high quality motors with encoders you can find lots on the Pololu website as "micro metal gearmotors" (AKA N20), with encoders. These come in a variety of power ratings and a large number of gear ratios. Pololu also sell a variety of larger motors, as well as motor drivers and motor controllers.

If you're looking at larger robots you can find a variety of motors with encoders on the ServoCity (Imperial measurement) and goBILDA (metric) web sites. These come in 22mm, 25mm, on up to larger motors. Of course, the larger the motor the higher torque, but also the often significantly higher power requirements (and lower battery life, therefore requiring larger and heavier and more expensive batteries).

If you're planning on having your robot operate outdoors or on uneven terrain, you'll want ball bearings on the output shafts. Plain bearings won't last long when bouncing over rocks.

So the first thing really to do is determine the scale of your first robot, then select a motor suitable for that scale.

sly sand
#

also brushless motors are the quality ones

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"Brushless motors have significantly higher efficiency and performance, and a lower susceptibility to mechanical wear than their brushed counterparts." ie: brushed motors are obsolete

pine bramble
# sly sand also brushless motors are the quality ones

As to quality, both are subject to the same variables. You can buy extremely high quality brushed motors, and crap-quality brushless. Brushed motors are hardly obsolete, still the most common motor one will find for robots, and a great deal cheaper. Small brushless motors are actually rather hard to find. Pololu doesn't even sell any, nor does ServoCity or goBILDA.

vocal bear
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brushed motors have their place

sly sand
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that's not the robotics I learned but whatever. Guess this channel won't be of use to me

vocal bear
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brushed motors are good in very dirty environments, for example

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personally I'd usually go brushless if I can find an appropriate motor, but brushed are not useless

pine bramble
modern pulsar
#

Please try to be respectful of opinions that don't match your own. It's fine to disagree, but remember that most folks here are other community members taking the time to provide assistance, and it is inappropriate and a bit rude to simply dismiss them.

pine bramble
#

If you do decide to go brushless and want to invest the money, there's a company in Texas whose founder was a member of the Dallas Personal Robotics Group (DPRG). The company is called Rev Robotics and they sell several models of brushless motors, and I can certainly confirm that those in the DPRG I know all think Rev sell very high quality products. But you will need a specialised brushless motor controller, gearbox, encoders, etc. and by the time you price all that the per-motor cost will be well over US$150.

sly sand
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that's all

pine bramble
modern pulsar
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Fair enough. Your wording came off more dismissive than that. Thank you for clarifying.

pine bramble
#

Do you come from an FTC or competition background? You must know that the world of robotics is wider than that.

vocal bear
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In school we learned on brushed motors only because they are simpler to deal with and we could focus on our control algos

sly sand
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What I learned is that there a triangle of compromise in robotics between actuators/motors and sensors and intelligence

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so if you skimp on one like using an obsolete tech like brushed motors or 17th century alkaline batteries you'll have to pay much more in other categories

pine bramble
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Yes, but there's nothing about brushed motors that actually makes them obsolete. They are perfectly fine as motors for the vast majority of hobbyist robots.

sly sand
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but I can't find a source for the triangle so I guess I didn't learn the proper robotics. And guess I'll just go to another hobby since I'm too old to learn

pine bramble
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There's a guy in the DPRG in his 80s who's just now learning Python and some new tech. He's been building robots for over 50 years.

sly sand
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I understand that brushed works for certain uses, but shouldn't you try to get BIFL products and/or get the most bang for your bucks when you can ?

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I mean if I get x HP/$ with brushless >> y HP/$ per motor with brushed shouldn't I not even consider brushed?

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I have to pay like 20$ shipping to even order a single chip when I buy chips so I try to get ones above my need because of the opportunity cost of having to reorder

#

Kinda like brushless vs brushed the same way

#

their price difference benefit is completly nullified by the 20$ shipping cost

pine bramble
#

A beginner can buy a brushed motor with gearbox and encoders for about US$15, and a motor controller for that for about $10, per motor. The lowest price brushless motor I've been able to find (with gearbox, encoders and controller) is about US$150, per motor. So yeah, if someone has no financial limits then go with the $300 option, but the $30 option will work for 95% of the cases. I've built quite a number of robots and never seen the justification for the expense. And I don't think anyone in the DPRG (which represents an enormous amount of experience) uses brushless motors on any of their robots.

I'm not saying you're wrong, or that brushless motors are a bad idea, simply that they're hardly a requirement or that for most hobbyists the expense and added complexity of the motor controller is justified.

sly sand
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Is it true that brushed motors tend to die quickly (within a month) in RC while brushless lasts much more ?

pine bramble
#

I don't know, I don't run RC cars or helicopters or planes.

#

They have very different motor requirements.

sly sand
#

I thought that you could ruun a brushless with a variable resistor and PWM too

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didn't know you neeeded a controller and gears

pine bramble
#

If you're running a helicopter or a car you still want gears but the output shaft is clearly going to be going as fast as possible. On a robot the opposite is the case: you want high torque and slow. So you want a gearbox. There's a difference between a "motor driver" and a "motor controller", the latter encloses the former as a higher-level controller so that you don't (as a programmer) need to deal with PWM at all. Brushless motors do require a different type of motor controller than brushed motors. I don't know if it's possible to run a brushless motor driver simply on PWM signals alone. From what I do know that does seem unlikely (but I'd be happy if someone with direct experience can clarify).

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I believe most of the brushless motor controllers can also do brushed, but I don't think the opposite is true.

sly sand
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I've been trying for a couple of week to start on a car robot but it seems there's 2 completely different aspects in it kinda like the unresolved problem of unified physics

pine bramble
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I'm not sure how an RC car robot and the unresolved problem of a unified theory of physics relate to each other, but I'm keen to hear.

sly sand
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on one side you have cheap smart cars projects you can't upgrade that are "naked" without a bodyshell and on the other side you have hobby rc cars with tons of parts with with proprietary parts (transmitter/receiver/ESC/batteries) that you can't access with arduino or a pi (like haven't found a successful comp^lete project in 2 days unless I have tons of skills in tons of stuff)

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so it seems to are completely separate and nobody has been able to put both together for a mainstream level of skills

pine bramble
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Have you heard of the Donkey Car robot project?

sly sand
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I'm not really that keen on car, just want a mobile, reasonably speedy, platform for sensors

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And I can't fly a drone in my city because all the city is in restricted airspaces

pine bramble
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That would seem to be exactly what you're looking for. It uses a car chassis but is a fully autonomous robot platform.

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And has been used by hundreds of people so it's a proven platform with tons of documentation and people with experience building it.

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There's a whole community around the Donkey Car platform.

sly sand
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interesting, seems to be an hobby rc truck conversion kit to make it smart

pine bramble
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You can use almost any RC car or truck chassis. The Donkey Car part is what you build on top.

sly sand
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otherwise do you know of something similar for a tracked robot with arms or a crane that isn't a toy but something more serious ?

pine bramble
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No, not unless you're willing to spend around US$10,000.

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The cheapest ones that aren't toys are at least US$5000.

sly sand
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I originally wanted to go lego mindstorms education version but it's completely proprietary and my sklills with arduino are useless on it

sly sand
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never know when I may have a windfall, I'd strongly consider the 12k$ DIJ programmable/moddable drone platform and a drone type.2 license if I did

pine bramble
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I'd recommend investigating the Donkey Car project as the chassis you choose can be almost any. If you are looking for a heavier and slightly more robust (but more expensive) chassis, I'd suggest the tracked Outlaw chassis. You could put a Donkey Car controller on top of that or design your own.
https://www.servocity.com/outlaw-chassis-kit/

ServoCity
Outlaw Chassis Kit
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RobotShop re-sell some of the $5000+ style robot chassis. Waaaay out of my price range, since by the time you add appropriate motors, controllers, batteries, etc. you're up to $10K.

sly sand
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I just got access to a MIT style fablab but I don't know these things yet so I 'm not comfortable with having to 3d print my own parts or cut them etc, i,d rather have a kit I just have to assemble and can upgrade with better motors/sensors etc

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ooff I see what you mean 😄

#

"You have a cute 500$ hobby RC car, if you have the money we have a 12000$ version"

pine bramble
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Ah, but there's the middle ground too. Say, use some kind of ServoCity chassis (which are highly modifiable and very sturdy), and appropriate controllers, etc. I'd back-of-napkin estimate you could have a functional autonomous robot for around US$2000.

sly sand
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chassis seems like a good thing to invest one if it's easily reusable and easy to mod

pine bramble
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I'm currently in the process of building a goBILDA-based Mars rover, and because the shipping to New Zealand is outrageous the total cost of the robot will be well over NZ$3500. So I'm doing it in stages, starting with a four-motor version with no rocker-bogies. So you could get a starter chassis from ServoCity and begin building in stages too.

sly sand
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it's not naked(has a bodyshell) and seems to be a good compromise between on-road and off-road for a mobile platform

pine bramble
# sly sand it's not naked(has a bodyshell) and seems to be a good compromise between on-roa...

There are a number of robots like that on the market, and that's a good quality robot. The only thing to consider with that style of robot kit is that they're not always very extensible/modifiable. And for that much money you can actually build a more capable ServoCity robot as a base platform, but you'd have to design much of it yourself (where the Leo is a kit but makes a lot of the decisions for you).

sly sand
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I'm in an ace age country too don't want to be unable to use my outdoors robot for 10 months a year

pine bramble
sly sand
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that's kinda why I absolutely need a shell

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and ideally a 10cm ground clearance

pine bramble
#

Well, it sounds as if you are perhaps on your journey now 😄 I've got to go. Nice chatting with you.

sly sand
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yeah thanks for the advices

pine bramble
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You're very welcome.

sly sand
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the problem with any project i want to make is there seems to be too many choices

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so I like to be constrained on certain decissions

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Like I want to make a rc car mobile smart platform. Ok need a chassis and motors and servos and ESC

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there are thousands of each

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I could make my own shell and own EC but again thousands of CNC machines and 3d printers plus I have to spend years learning it

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so in the end I always give up because of too much choice and it seems I need to learn as much skills as an astronaut or nuclear engineer

mortal dagger
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How large motors are you looking to run?

sly sand
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can't find my old posts but I'd like a 4wd off-road outside platform that can carry about a 200 pounds load and be around 1 feet large/1 feet long. VColtages involved from my old research would be 16-20V motor for each wheel

mortal dagger
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Probably need some pretty hefty motor drivers for that.

sly sand
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found a piece of my old posts, I had found a pl;atform that seemed to be decent and it was driven by 4 650mA@12V motors

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this one was with mechanic wheels and steel robot chassis but with a 40kg load so 70ish pounds

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so not quite what I'm looking for and was a naked platform too (no weatherproof bodyshell)

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it was 400-500ish$ I think

pine bramble
# sly sand so in the end I always give up because of too much choice and it seems I need to...

Well, I could post the old cliche of "a journey begins with a first step" or something, but being disabled by choice is a privilege not everyone has. One of the members of our Personal Robotics server is a 9th grader living in New Delhi who builds robots out of junk, and frankly puts a few of us with much greater resources to shame, in terms of actually getting stuff done rather than talking about it all the time. So starting with even a smaller kit and beginning to build on that is truly a start, and once you get into odometry and sensor handling is probably more "real" robot than most people actually ever build. Most people end up with remote-controlled, robot-shaped toys.

The actual hardware to build an autonomous, self-navigating robot is really not that big an investment, but can take a great deal of effort to get running, and could provide many years of learning. Buying board after board, sensor after sensor, just makes us consumers. Digging into a single robot project and maxing out what can be done with just that base platform is something I see few people (myself included) actually accomplish. The advice I've had from one of the more senior, experienced members of the DPRG is to do just that: stop monkeying around buying stuff and just build a single robot and get it running. And then, as he says: "Run the robot. A lot."
http://robots.org.nz:9627/wiki/Wiki.jsp?page=BuildSequence

Personal Robotics Wiki: Build Sequence

Page version 3, last modified by Admin, on

sly sand
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that's why I want one that can carry a load, I recently was diagnosed with osteoarthritis and this could help my quality of life in the long run

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But yeah I understand the "not starting with blacksmithing gold (which is very expensive and technical) when you don't have the skills the handle it when you could start with inexpensive tin and make mistake" that I should heed 😄

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This is more of a "can't change it" problem though

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because if I could mod them a mainstream hobby r/c car would be perfect same for lego mindstorms

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but hobby r/c car are proprietary, if I can't send commands to the ESC I can't make it stop and override the RC control if it's going into a wall

pine bramble
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I'd say probably the cheapest way to get started at that scale of robot (i.e., one strong enough to carry things) would be some kind of ServoCity or goBILDA chassis kit with a RoboClaw motor controller and Yellow Jacket motors. That in itself is pretty expensive as a start, but you could build on such a platform for many years. The Yellow Jacket motors are expensive but very powerful, and the whole Lego-like nature of those products means you could continue to add features as you like. You could start with a two motor robot and then as you go add a second pair of motors. Like I said, I'm working on a four motor start on a Mars rover and will add another two motors and the rocker bogies later.

If you start with more of a fixed kit that has a bespoke chassis (rather than Lego-like) it makes it much harder to modify in the future.

sly sand
#

and they often add things even to the motors like sensors and a controller chip so that it's PWM/SBUS but proprietary and can't use it without their ESC

pine bramble
#

We often get people coming into our forums with ideas of building walking robots as big as humans, and it's hard to tell them that very large teams of people (such as at Boston Dynamics) have spent years and millions of dollars on hardware and software R&D to build such things. They think they can do it on the cheap.

And they also arrive with no existing hardware or software skills and just think they can just jump in and suddenly have Robby the Robot. And when I suggest they might start with a small two or four wheeled navigational robot kit to learn the basics required to even begin such a larger project they then just give up. Or when they realise it is actually going to take some serious effort at learning hardware and software skills they weren't up for that either. So they weren't really serious after all, which is the nature of people I guess, i.e., getting enthusiastic about something but the enthusiasm quickly wanes. Like the idea that it might take many years to play piano or violin or tabla.

So like I said, if anyone is actually interested in building a robot, start going down that path by considering one's goals and then jump in with some appropriate level of kit to get going. Over the past few years I've kinda assembled notes about this, including things from some of my friends, and collected it here:

http://robots.org.nz:9627/wiki/Wiki.jsp?page=GettingStarted

Hopefully that gives people at least the ability to begin thinking about what they might want to do rather than just "build a six foot tall walking robot", which will never happen unless one is independently wealthy and can hire a large team of hardware and software engineers. It's nice to dream, but it's also nice to have a working robot that's more than a toy (which gets boring pretty quickly).

Personal Robotics Wiki: Getting Started

Page version 1, last modified by Admin, on

sly sand
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I see, not like electricity vs electronics then where more weight and more voltage usuallly mean simpler than a microelectronics version on an arduino/chip

pine bramble
#

A fairly limited but pretty cool start is the little tracked Zumo robots from Pololu. I've seen people do pretty amazing things with them, and they just run on an Arduino, a pair of small N20 motors and four AA batteries. So that's the smaller end of the size scale but with a single Zumo you could spend years having fun with it. I've even seen AI style cameras mounted on them running around in a house following people. The KISS principle is certainly true with robots.

sly sand
#

seems like a great start and buyable in canada without astronomical customs fees

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ant not a dead-end like all those cheap "smart" cars kits with cheapest parts and yellow wheels

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last question, do these sort of things, robots, robots parts etc ever go on special? surely even parts for industrial/scientific applications ruins sales sometimes ?

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ie: should I wait for black friday/christmas ?

pine bramble
#

The one downside of the Zumo is that it's pretty difficult to add wheel encoders. I managed to do it (and blogged about it here: https://robots.org.nz/2021/05/26/in-pursuit-of-the-club-robot/) but at the point where you want to begin exploring odometry you'll hit a wall. But you can also kick that can down the road for a long time, as there's lots to do with a Zumo. Pololu does follow the US cycle of sales, and have had Zumos and their parts on sale. So yes, I imagine you'd see things on sale. I can say that Pololu are really nice, helpful people and if you mailed them they'd probably even tell you when the next sale date is going to be. I've had excellent tech support from them. There are a handful of companies like Adafruit, Pimoroni, Pololu, SparkFun, etc. who are very helpful and running solid business models and supporting healthy communities.

sly sand
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odometry seems to have a lot of solution like an opentx transmitter/receiver though

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seems to be more of a problem of fitting/attaching/screwing the receivver to something that wasn't made for it than anything else

#

but opentx gear usually is made to be pretty universal, same with FPV style cameras etc

#

hum opentx is telemetry nvm

pine bramble
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I'd say odometry is a very fundamental feature (with requisite hardware and software skills) necessary for proper robot navigation. Without odometry your robot can't even run in a straight line. One of the DPRG challenges is to drive a robot from a fixed mark forward about twelve feet, turn around and come back to the origin point. Their robots are nailing that within fractions of an inch (like 1/8"), simply impossible without odometry. As a "first challenge" it's exceedingly difficult. I've not managed it yet.

sly sand
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Basically I've followed a couple optional electrical engineering courses and a robotics semi-graduate course and I've been looking to use that theory every since

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The end-result of the course was being able to find the noise equationss of sensors with matlab so you could make a simple kalman filter to do sensor fusion

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but we didn't build anything or take measure from the sensors, was just the theorical side of things

pine bramble
#

Sure, and one picks their battles. I'm not a math whiz so I ended up using a BNO055 IMU, which does the sensor fusion for me.

sly sand
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yeah what i'll do as well. Liked the specs of that Bosch chip

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I never liked how my university was too theorical

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I don't see the point of a robotics course if you don't know how to build a robot to actually measure anything with the course 12 years later

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They were more interested in training future PHDs than peoples who wanted a job with real-world constraints apparently

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almost half of it was on autonomous driving as well and the pros and cons of various types of navigation

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and various sensors that could be use for navigation

vocal bear
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this has been a fun conversation to lurk thru

pine bramble
#

Yeah, sure. I built a robot in high school back in 1979 and got back into a few years ago, inspired by a YouTube video by David Anderson of the DPRG. I'm happy to say we're now friends and he remains an inspiration. To give you an idea of his prowess, he has a six wheeled outdoor robot called the jBot, with wheel odometry and an IMU, and with that demonstrated the ability for his robot to do that origin-to-waypoint-and-return challenge, but do it outdoors over 1000 feet, with logs and trees and rocks in the way. At the beginning of his "second hat trick" video (in the Navigating Through the Woods section) he drops his hat on the ground as the robot drives off, it goes up to a virtual waypoint, turns around and comes back, driving over the hat. It's hard to explain to people the genius of that work. Just with odometry and an IMU, no GPS. David is by far the most advanced at robot navigation I know of. Bar none.
http://www.geology.smu.edu/dpa-www/robo/jbot/index.html

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So if anyone needs a challenge, just try to emulate that trick... it's actually one of my own goals.

sly sand
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my teacher was part of a robotics labs that mostly advanced research on industrial robots, crowd of cars self-driving vehicles and aerospace fields

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one of the student had built a fast walker cat that mostly used mechanical legs and that neeeded almost no power because it could keep going just because of the properties of springs

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I mean I can't even get started on a robot car and meanwhile they sold several patents on making an automated garage that can recharge electrical cars and make basic repairs to a large carmaker...

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I guess if I can get past edge-following navigation that would be nice

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And actually do voronoi navigation so it doesn't just follow edges...

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I'll setup a pricewatch on the Zumo 32U4 Robot Kit

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seems to be what I need to finally start on robotics and seems to be expendable and not the cheapest of the cheapest quality

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My 1st customization goal would just be to have it run away from me in fear 😄

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and kinda playing with it by trying to fool its sensors so it doesn't detect me

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ie: like dressing in black to avvoid IR sensors or blinding visual ones with a bright light

sly sand
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without realizing that things have become much more specialized, smaller and with much more tools today

#

and much more complex

#

and much more laws too and safety things

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and even magdeburg guy with his vacuum sphere public experiment didn't raise the horses from birth or smelt the sphere, he had a team

pine bramble
# sly sand I guess if I can get past edge-following navigation that would be nice

Yeah, but on the other hand, I can buy an advanced Time of Flight sensor the size of a grain of rice that has centimeter accuracy at 4m and uses about 20mA, or a BNO055 IMU, which is a truly advanced device, either for about $20. And we can build what was sent to Mars in the 90s now for about $2500. So the sky's the limit nowadays.

sly sand
#

yeah but if you are completely uselesss at building stuff like me you depend a lot of otherss

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I'm working on that especially with fablab courses and membership but atm I can barely solder and can't cnc/3d print anything

#

and even then back then you had a reliability and scaling up that you don't have on 20$ chips from today

pine bramble
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I avoid 3D printing as it's actually a religious cult from Mars.

sly sand
#

it always impressed me how old servers like cray or SGI outperform today computers when reliability is a thing or parallel I/Os

sly sand
#

since without a chassis I can't even start

primal shell
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I don't avoid 3D printing, as it's a fun way to prototype stuff. I could just CNC stuff, I suppose.

quadruped-robot-2.jpg
pine bramble
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See?! Every time I mention it's a cult a bunch of people tell me how wonderful 3D printing is! 😱 Next thing is I'll be a ceremony with thousands of other people getting married to a stranger... 😝

primal shell
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There are other approaches

mecano-robot.jpg
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Or pre-built chassis

rainbow-robot.jpg
sly sand
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well porsche can honor warranties on their 1950s cars because of 3d printing from powder metals

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I kinda think it's a cult too atm, but as industrial-grade ones get cheaper I think it will get more interesting

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Hopefully in my lifetime we can prove the RIAA wrong and download a couch

sly sand
#

@pine bramble bought the newbie robot we talked about, seems to be at a low price point in its price history atm so don't think it will be cheaper around black friday/etc

vagrant thunder
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I mean, 3d printing is a fun hobby, but the time it takes to go from nothing to printing takes either a considerable amount of time and effort, or a considerable amount of money. I picked it up out of curiosity, but it really is one of those things where the only way to learn it is to do it. For most, it might be easier to start with plywood or t-slot extrusion.

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I'm scared to count on black friday for most electronics this year.

sly sand
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I have a fablab 3 streets away from me so I can use their 3d printed stuff at cost

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and they have a mid-top end one

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or their CNC machine or various saws etc

vagrant thunder
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Yes, but learning fusion360 is a process as well haha

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Also, there's a difference between "they let you use their printers" and "they print it for you."

sly sand
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They say their 3d printing stuff is: Printrbot Pro / Tevo Tarantula / Sense3D

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And they give a course so you can do it yourself

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I initially went because my apartment is too small to solder, my 2 smoke alarms would go crazy and I'd probably drown from my sprinklers 😦

native cipher
sly sand
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@native cipher Zumo 32U4 Robot Kit (Assembled with 75:1 HP Motors)

native cipher
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nice! I love Zumo.
it has gotten pricier, though

sly sand
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was 200$ cad, about 155 US$. But worth it for me because the alternative was very cheap 80$ smart cars you can'tr upgrade/customize with flimsy boards and flimsy yellow wheels and the cheapest of the cheapest sensors

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and most of them don't even have documentation

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thanks to me it passed to unavailable - we don,t know when it will be back in stock on amazon 😄 🤣

pine bramble
# sly sand <@!828135237744984114> bought the newbie robot we talked about, seems to be at a...

Ah well, congratulations on your new robot! You might even make yourself a robot sumo arena and find someone in your area to compete against. One of the DPRG members put black tape on his nice wood floors (the horror!) and had his drive all over his house using the line follower. Others have put analog IR sensors or ultrasonics on theirs and gone off-track. Sky's the limit! 😃

sly sand
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I hope so, the controller chip seems a bit limited compared to a mega 2560

native cipher
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it is, which is why I am building my own alternative zumo-based robot using RP2040. But 32u4 is powerful enough for quite a few things, so it should keep you busy for a while.

main echo
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anyone familiar with controlling a mini-cheetah-style motor with CANbus and Arduino? I am hacking that and I have a few questions about things like max CAN messages per second.

sly sand
sly sand
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so, just theorically, I saw some 80 kilowatt servos on digikey, what kind of stuff would that rotate related to robotics?

native cipher
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I can't even imagine... can you share the link, just for fun?

sly sand
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say rated output 15kw

sly sand
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While perusing brochures I've seen some lines of servo motors going from arduino scale (mA/5V) up to kw before and that always kinda surprised me

vocal bear
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I also don't know of a robotics application, but maybe a big servo like that could be used for very precise motion of a huge armature/load

sly sand
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Trying to read robotics related phd thesis and I'm already lost in the first line of the introduction 😦

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I'm lost at "cable-driven parallel mechanisms"

lone skiff
native cipher
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@lone skiffthanks! Haven't seen such designs before

sly sand
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to make a planetary homerun

vocal bear
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That's an interplanetary home run lol

lone skiff
sly sand
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I know about it that's why I picked 0.2c 😄

versed jungle
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hello guys could anyone plz suggest the resource to find the best topic title to fix

sly sand
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new kitten has arrived, but it's cold atm due to canadian ice age. Screwdriver on the side for comparaison

IMG_20211119_121541.jpg
jolly eagle
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is it common to be able to flip axis on something like LSM6DS33 or MMAB451 for space reasons? im flying a rocket and wanted to mount the board so Z was away from the ground(but cant because its too wide to fit in the tube that way) then X and Y would be whatever, but say I turn the board on its side and have X be away from the ground, will it mess up anything like the gryos, mag etc or as long as I know which orientation goes to which axis then it will work the same?

sly sand
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They probably use matrixes for calculation and you just apply a rotation matrix before feeding your matrixes to it or getting matrixes from it

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but yeah imho it seems obvious that you have to calibrate sensors at least to tell it where 0,0,0 is and your rotations

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LSM6DS33 seems to have a register for user-orientation of axes