I would appreciate if someone can tell me what went wrong. We had a successfuly waypoint test last week. On Monday, we did another test at higher altitude, 200 m, and longer distance on Align's flying field at riverbank. The flight was normal at first but shortly after switching to auto mode, a military helicopter flew nearby - at much higher altitude off course. Somehow, the MP screen showed the quad changed from auto mode to loiter mode by itself, then it descended straight down slowly but steadily (still in loiter mode as shown on MP). I tried to switch to RTL, then loiter, then stable, neither was working. I couldn't take the control back. The quad continued to go down steadily, and eventually into water.
I attached the tlog here. At first I thought it's GPS failure because of the military helicopter but GPS seemed to be OK. Battery was almost full before takeoff and it's still a new battery. So it's not battery failsafe either. I don't understand why the quad went down when MP show it's in loiter mode. Also, why I couldn't switch to RTL or stable mode?
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...to be fair, the APM was not at fault here. The RC system failed for what ever reason. In fact, if the APM was configured correctly, it would have in all likelihood, saved your copter!
You can set the failsafe for RTL instead of LAND. Then this won't happen.
... yes I know ;) I had a similar episode early on when I was playing with my battery fail safe settings after implementing a custom current sensor. I thought everything was disabled but about 5 minutes into my flight, my quad descended into the harbour thinking its batteries were about to give out - it was still at 75% but the sensor was reading way too high and it entered a LAND sequence due to battery failsafe and there was nothing I could do.... I had to replace all electronics including gimbal controller and camera... Not quite as bad as yours but I do feel the pain....
Posr the .log if you recovered the uas, thats where the answer is.
I uploaded the .log from my skyhunter in another thread. Would you look at it and find out why the airplane was going down in auto mode?
That's simply not possible, current was rapid midstream. I lost everything.
Looks like you had a radio failsafe at 88.8% without having set up any provision for it in Arducopter. At this point Ch3 drops to 900 (normally 1100 min) and Ch5 goes to 1552. 1552 on Ch5 obviously changes mode to loiter in your setup. All other channels stick around 1500. From this point none of the RC inputs change at all till the end of the flight (ie your receiver never managed to connect to your transmitter again). Ch3(throttle) at 900 is the reason your copter descended (min throttle in loiter). You are lucky you ended up in loiter, almost any other mode would have had a much worse outcome...
Lesson: Setup your failsafes. RTL probably would have saved you on this one...
Thank you for your comments. Throttle low values did explain why the quad going down in loiter mode. Just checked my radio (Futaba 14SG), and found ch3 is off when failsafe. An expensive mistake on my part. Yes, ch 5 switch in the middle is loiter, it is set as stable-loiter-auto.
one question. I may fly out of the range of radio transmission in auto mode. Can APM tell the differences between going out of radio range and radio-receiver communication being interrupted? I mean, if I set receiver failsafe to RTL, will the quad do RTL when flying out of radio range even I want it to continue the mission?
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