AltHold and Loiter Oscillations+Wobble

ArduCopter Copter 4.0
1

Hello,

Have an octoquad that I’ve been flying for the past few weeks now.

Last week the team finished the auto tune procedures for the pitch, yaw, and roll. The aircraft flew like a charm, multiple successful loiters and RTLs over the course of about two hours.

Today we took it out, and put it in the air. After switching to Alt Hold the aircraft looked fine, and upon switching to loiter the aircraft began to oscillate and wobble along the pitch axis until it flipped it self over and nose dove into the ground.

Any ideas on why this would have happened?

I downloaded the two latest created datalogs from Mission Planner, and put everything that was downloaded into the following folder.

Any help would be appreciated.
https://1drv.ms/u/s!Av0B8mOYCL0WgZEFEQJbiI1k9AZDPA?e=pF3zHY

2

I think you just got lucky on previous flights and the increasing oscillation on Pitch seen here was just a matter of time and circumstance before it happened. The Pitch PID’s do not look right (compare them to Roll). Possibly because of the lower than default Auto Tune aggression you set. You want this tuned at 0.1

Also, you enabled the Dynamic Notch filter but didn’t set the parameters. That should have been done before Auto Tune.