Px4-autopilot: Misfire at catapult launch (custom FW version 1.7.2)

[MartinStokelj]

Describe the bug
From 55 test flights we had 2x misfire at catapult launch. It looks like PWM was not send on ESC and motor didn't start. I need suggestion what to check in ulg files.

To Reproduce
We do not know how to reproduce.

Expected behavior
Motor should always start at catapult launch

Log Files and Screenshots
ULG files
misfire2x.zip
or
https://review.px4.io/plot_app?log=530849b9-21cb-4097-9acb-cf0d311b97bf
https://review.px4.io/plot_app?log=b78cdaff-b13b-43a9-8d57-0168c43b90e7

Drone (please complete the following information):
https://www.unmannedtechshop.co.uk/product/unmanned-pixhawk-autopilot-kit/
pixhawk 2 fmuv2
Stack: PX4 Pro
Vehicle: Fixed wing
FW Version: 1.7.2 custom build

[MartinStokelj]

Any suggestion what to check in ulg files?

[julianoes]

I'm not sure either. I can see the acceleration spike which probably should be detected, and at the bottom of the file there are some debug messages as well.

It would be interesting to also see a logfile of a successful launch to compare what is different.

[MartinStokelj]

I'm not sure either. I can see the acceleration spike which probably should be detected, and at the bottom of the file there are some debug messages as well.

It would be interesting to also see a logfile of a successful launch to compare what is different.

Here is:
https://review.px4.io/plot_app?log=fb8b6e04-6f15-4f3d-af5d-467ec1546217
or
log002.zip

https://review.px4.io/plot_app?log=be07ef0d-e1a3-4518-aaad-c65c13f42647
or
log003.zip

I can give you more if you want...

[julianoes]

I can't see anything obvious, sorry.

@Antiheavy maybe you have some comments or insights on this.

[MartinStokelj]

I can't see anything obvious, sorry.

@Antiheavy maybe you have some comments or insights on this.

Can you suggest what to check if this occurs again?
I thought that is maybe connected to bad GPS connection even if the "COM_ARM_WO_GPS Allow arming without GPS" is on.
Is it possible that catapult launch shocks GPS to much?

[MartinStokelj]

@dagar did you had the time to check this?

[MartinStokelj]

Today we had another misfire at catapult launch

https://review.px4.io/plot_app?log=5276768d-8b93-4237-a8e6-b38f9ed6ee0d
or
log001.zip

one flight before all went ok
https://review.px4.io/plot_app?log=e3a8f668-5968-4c04-9f06-10bd00230a85

[MartinStokelj]

We think that maybe is the param LAUN_CAT_A (Catapult accelerometer threshold) the problem...
We have it on 20, is this too much? I don't know which value do I need to check in ulog files to confirm this (in theory - threshold was not in range)

[MartinStokelj]

@dagar , @julianoes
During the last missfire we putted drone on debug link, and called "Reboot" after reboot there was still problem that there was no PWM. So we tryed "px4io stop" and then "px4io start" after that all worked ok.
Since this is old FW anyone know what was the fix if px4io stops working correctly?

[dagar]

Sorry, there isn't much to go on because the internal px4io state isn't logged. If we could get you synced up with master we could start adding additional px4io instrumentation (logging).