Hi All-
First i have to thank everyone on this forum for providing such an amazing pool of information and helpful discussion. I hope someone can help.
Specs:
APM 2.6 - ublox gps with compass & 3dr OSD. Also using dragonlink for control, plus RFD900 long range telemetry radios.
I was flying in a new location and was testing my RTL functionality before going for a flight. I flew stabilize, then switched to loiter, then RTL, then landed. Took off again in stabilize then hit RTL... the copter started to come in the correct direction, then suddenly darted in one direction into the woods. I checked my logs for GPS failures, mag interference, mechanical failures and even checked my vibrations. I can't find what could be causing this! I'm afraid to rely on RTL until i can find a cause for this.
Even on my successful flights before/after the crash, loiter does not just sit in one spot, but kind of goes up and down. Not sure if it matters but I am flying by a lake, and the area I took off is flat, but 3 feet away the ground is sloped down towards the lake.
Attached are my logs - any help would be greatly appreciated.
Replies
Have you checked your compass orientation is correct. I just spend a week troubleshooting interference, gps glitches etc and found the external compass was configured for 180 degrees instead of 0. Fixed my problem.
So what was your solution?
Looks to me like a GPS issue. The UBLOX hdop reporting isn't quite right, but you can see on this graph that during the second RTL, the reported hdop is worse. On the second graph, we look at the position error the nav system is seeing, compared to hdop during the second RTL. At first, the position error is positive, then all of a sudden the position error goes negative, just as hdop gets worse...
I just got something very very similar in all details.
uploading my log too.
-- benoit
2013-07-26 23-12-27.tlog