Strange uncontrollable behavior when using Loiter

ArduCopter
1

I am helping a friend figure out an issue where when he flies in a systematic turn (mixing roll, yaw and pitch), the front of the quad dips and becomes uncontrollable. Control is regained when switching back to Stabilize. I believe the issues is due to a faulty power module whereby the Pixhawk 2 is not reading amp data. We noticed this when doing a CompassMOT calibration and saw no amp reading. I believe I have confirmed this in the flight logs and was hoping I could get a second set of eyes to look through the logs.

I have also found this message in my auto analysis log: mission planner NaNs FAIL - Found NaN in CTUN.DSAlt

.bin file

Thanks

2

Interesting log.
Yes the current sensor has something majorly wrong with it, cable, sensor.
You probably need to check the voltage out of the current sensor connector.
Or just replace the sensor.

The quad is very overpowered/underweight which is causing the FC to literally cut the power to some motors during flight in an attempt to maintain attitude.
The PID’s look a bit on the touchy side as you have a lot of overshoots when looking at desired v actual in roll/pitch.

Have you dome an autotune?

3

Yes, I’ve done it several times.