Hi all,
I had a quite interesting flight / crash today with APM 2.5 firmware 2.8.1 on a ArduCopter QuadCopter v1.0 Frame.
I was testing auto for the first time and made a simple flight with 5 waypoints.
Waypoint 5 is LOITER_UNLIM.
The weather were perfect. Almost no wind (~2m/s).
I did a few test with 4000mA battery. It did go ok except from waypoint 5 where the quad were up and down (I had to go out of auto once to avoid crashing). Those flights are not on the attached log file.
After that I changed to a 2600mA battery and made one auto flight which performed perfect (the first auto in the attached log). Second time I started in auto from a little higher altitude and from some distance. The start seemed ok, but after that the quad gained altitude very fast. I did try to set RTL and after a while I set STABILIZE with low throttle setting.
At that point I was quite sure I would newer see the quad again (telemetry on my Spektrum DX8 were at that point missing).
After what seems to be a long time i started to hear the quad again and saw it "tumbling" down with motors rotating slowly. The voltage were at that point 10.4V if I remember correct.
The end of it were that it crashed in an area with long grass and bushes and I was so lucky that I was able to track telemetry and I were able to ARM the motors and I was at that point so close so I could hear it.
Damage report: 1 prop. 1 landing leg, a few nylon screws. Yes I was lucky.
Well Im very new so any idea to what happen? If I see correct in the log there are some very strange things going on with the pressure gauge.
Thanks for any help and Im still very surprised how easy it is to fly that quad!
/Benny
Replies
I had a look at the log.
The throttle cruise value is the hover setpoint. It was too high and caused the copter to rise. Switching modes multiple times from Loiter to RTL and back during the flight caused the desired altitude to be reset to the current altitude each time.
The meant the copter was doing what it thought it should. Had you put it in RTL and waited, it would have come back as the throttle I term would have kicked in and brought throttle cruise value back to it's intended value. that can take 10-30 seconds depending on the gain. When things go strange however, that's a lifetime.
I've put a sanity limit of 100m above home on the RTL altitude so that doesn't happen again. Or at least it won't go nearly as high. Loiter will still take the current altitude, but you can pull the throttle low on Loiter and bring it down manually.
Jason
Have you shielded the baro sensor, as shown in the manual here?