GPS Rescue - Failsafe on switch test fail

[smoky tusk]

So I tested "gps rescue" on aux which worked fine. Repeated multiple times. All good.

Next step was to ensure "failsafe" would work, so I put that on an aux channel.

Sats 19
Quality: 0.7

Aux1- disarm/arm
Aux2- air/angle/Failsafe
Aux3- 25mW/200mW/0mW
Aux4- gps rescue

I flew 90m away, and activated failsafe(16s into video). Instead of turning around to face home point and then climb to returning altitude like previous, it throttled up drastically.

At 100m alt I disarmed, when I rearmed you can see angle mode engaging and the quad leveling, the radio states "telemetry recovered"

The quad is alarming throttle and arms witch, but the quad has armed, and angle is engaged. I just had no control and craft kept falling.

One thing I find looks odd, is when I engage the failsafe, the flight modes at the top right does not display !fs!

It instead starts flashing between air and angle.

DVR- Footage: Both of these DVR's were done on the same battery without unplugging. Plugged in, Armed, flew and did GPS rescue. Back to air mode, rearmed and then performed the failsafe on switch.
Flight 1 - GPS rescue on switch - success
https://youtu.be/ckV9rmmtjDY

Flight 2 - Failsafe on switch - Fail
https://youtu.be/ckNk3Vx0amM

[hexed linden]

The video is not sharp enough to see the messages.
It should look something like this (analog video)
https://www.youtube.com/watch?v=zWmHuoiytG0
If you enable 'warnings' on the screen, you should see RESC during a failsafe-initiated GPS Rescue.
Please read the wiki carefully.
http://betaflight.com/docs/wiki/archive/GPS-Rescue-v4-4
NEVER disarm mid-air when you do a switch-initated failsafe, just revert the switch.
Test these things up close and at low altitude (30m away and 5m up is enough).
Be sure that you configure your failsafe stage 1 settings properly.

[smoky tusk]

I was 90m away but I did it essentially level with myself as it was down hill.

I don't understand why it jammed the throttle on initiating the failsafe switch.

I will check out the above video aswell :)

.
So in his video @hexed linden as soon as he activated failsafe switch, his quad turns to face homepoint and then goes to correct altitude. As is correct and worked with my "gps rescue switch"

1m 34s - fail safe switch activated, Rx loss seen, alt 1.7m from take off.

Home point directly behind quad.

1m 38s (4s later)

• Home point still directly behind, is hasn't turned.

-Battery voltage is sagged as its full throttling up

-altitude now nearing 100m (reason for disarm)

To me it looks like it never initiated the gps rescue in this failsafe.

I need to get out and try again and try to find the source of the issue.

[hexed linden]

Yeah I'm using the failsafe switch method.
However I bypass stage 1, to get directly into the stage 2 rescue itself.
I will try with it set to stage 1 and make sure that works properly.

Be sure your stage 1 settings have throttle set to a gentle climb, in my case around 1300, and that they enter Level mode, and that the switch positions you set for stage 1 can't do anything bad. Check the Stage 2 guard time is 1 second, maybe 2, but no longer; I personally think 1s is enough.

The sequence is climb, rotate, pitch forward.
So for some reason yours climbs super fast.
You see that stupid row of numbers across my screen? They are debug values.
If you choose the RTH debug it will put numbers there that show the phase of the rescue.
This might help us figure out what is going on.
Also if you make a log with the RTH debug that could help.
It looks as if it enters climb, with a massive climb rate, and a target height that's really high.

Check your CLI values for the climb....
try pasting these into the CLI.
When you test, and you only need to be 50m out from takeoff point, it should climb only 5m above the height when you initiate, at 5m/s, so after only about a second it should rotate towards home

set gps_rescue_alt_mode = CURRENT_ALT
set gps_rescue_initial_climb = 5
set gps_rescue_ascend_rate = 500```

Also check the altitude readings make sure they are OK and they don't madly change after takeoff.

[smoky tusk]

This is correct, i have 1500. I could lower that slightly but it works fine on "gps rescue" switch. 1500 probably is a bit high since auw is 750g

Guard for stage 2 is 1.5s

Hmm, I assume default for failsafe switch is stage 1. I could change that to stage 2 I guess?

So the altitude is set to max +10m(default)

I think I went to max maybe 10m in that flight? I'm pretty sure it's also set to 2m/s max climb.

I think this confirms that it entered stage 1, and for some some reason never entered stage 2 at all. Possibly because it throttled to high at 1500?

[hexed linden]

Please read the wiki carefully.

The gps rescue mode switch bypasses stage 1

A real failsafe ALWAYS goes to stage 1 before stage 2

Throttle of 1500! What do you think would happen if you give that much throttle to a quad? It will shoot upwards. Use a value that hovers or climbs just a little bit, set it carefully. This is emphasised clearly in the wiki

[smoky tusk]

"It is better to 'err on the high side'; climbing too fast is usually less of a problem, than dropping like a stone, when you have signal loss"

Just used 1500 as a starting point to see since.

So from this is the thought that it was climbing to fast and messed up the recovery?

My understanding is that that the stage 1 should have used 1500 throttle for maximum 1.5s before stage 2 kicked in and adjust alt accordingly.

But it throttled up for over 4s until I disarmed with no sign of slowing down.

I will get a more accurate hover value entered in prior to next testing

[hexed linden]

Truth is, I don't know what went wrong. Maybe the flash resulted in some bad values? Maybe under high acceleration your Baro gave false values? There are lots of possible reasons, and we need to be methodical if we are to figure out why your specific setup doesn't work when everyone else's does.
You need to check everything methodically, and follow the advice in the wiki.
I do know 1500 would make my quad climb really fast.
Check everything. Go to the CLI and type get gps_re and confirm every setting makes sense.
Then test the flight behaviour cautiously.
Test simple failsafe behaviours by setting stage 2 to landing, not GPS, with a long stage 1 time, so you can check that stage 1 works as expected, and set the hover values accurately. Check your GPS works properly while connected to configurator and gives stable values. Check the baro appears to work properly when you turn off GPS but look at altitude values. Then enable GPS Rescue, and show the RTH debug on your OSD. It will log the phase of a rescue and any sanity checks that may be counting up/down. Then do tests at low altitude and close to home with default values.
Practice using the failsafe switch to terminate the rescue so you don't panic and disarm.

[smoky tusk]

Understood. There's no barometer onboard, 1 less thing to worry about.

I'm at work now for a few weeks but I will get back to testing this as soon as I'm home and report back.

Thanks for taking the time to help

[hexed linden]

You’re welcome. I’m sure we’ll sort it out.

[frigid beacon]

Can someone assist, my settings are set by default at the Failsafe Switch to STage 2 .. everywhere I see, everybody has it to Stage 1 .. what is the difference ? Rather ask, then test it before ..