UAV crash false positive

[rsawtell]

UAV's undergoing sufficient acceleration will trigger the crash plugin, disabling their rotors despite hitting no obstacles. I've experienced this with the X500 but I assume it is not specific to any single UAV.

To replicate, use the cave environment (for sufficient vertical clearance)

rostopic pub -1 1/cmd_vel geometry_msgs/Twist -- '[0,0,8]' '[0,0,0]'
wait for the UAV to get up to speed (approximately the top of the cave entrance rock outcropping where it turns to grass)
rostopic pub -1 1/cmd_vel geometry_msgs/Twist -- '[0,0,-8]' '[0,0,0]'

To be sure, I had a second UAV at a higher elevation than this so I'm positive it was not hitting the invisible ceiling.

I suspect it can be triggered at lower velocities as it was not going this fast in the initial run where I saw it happen with our solution, but this does it for me consistently without being dependent on our solution.

[peci1]

Are you sure 8 m/s downwards can still be considered a controlled flight? :)

[rsawtell]

I had some more time to test this morning, a little less extreme but will also trigger it:

rostopic pub -1 1/cmd_vel geometry_msgs/Twist -- '[0,0,5]' '[0,0,0]'
wait for the UAV to get up to speed (approximately the top of the cave entrance rock outcropping where it turns to grass)
rostopic pub -1 1/cmd_vel geometry_msgs/Twist -- '[0,0,0]' '[0,0,0]'

[hilario]

We are also experiencing false positives with the UAV crash detector.

[nkoenig]

See PR #965

[iche033]

alternative fix in #973