This is my first post here, I've only been using APM for a few weeks on a DJI F450 Quad and so far it has been going well, until today. I'm using an rctimer APM 2.5.2 board with the latest firmware v3.0.1
I'd been out flying earlier in the day and was getting some "toilet bowling" when using loiter, when previously my copter had been nice and steady in loiter. After reading around a bit I decided to recalibrate the compass. So I went through the live calibration and compassmot - which came out about 58% I think - not great, but not bad, and no worse than the last time I did it.
Went out to test fly in the garden. Started off in stabilize, all ok, switched to Alt hold, still good, holding altitude well, all behaving very nicely. I then switched to Loiter and whoosh, the APM applied full throttle and (what I assume was) full pitch back shot over my shoulder and smacked into the back of the house :-( By some miracle, the copter seems to be ok (and still flies in stabilize), though it did put two nice scratches in the glass in my back door :-O
So, I need a little help triyng to work out what went wrong? I've attached the logs (my switch to loiter is at line 2246) and a couple of plots I've done. You can see where it goes totally bonkers immediately after I switch into loiter. I initially thought that the "problem" was that WPDst=2.5, but after a bit more reading, I see that means that it thought it was 2.5cm from where it should be (have I got that right?). So that shouldn't have caused any major movements right?
GPS hdop and nsats both look good, so I don't think it was a GPS issue.
The numbers that look odd to me from NTUN rows are PErX and PErY - distance to intermediate target(what do these mean, what are they exaclty?) - and VelX and VelY - velocity estimates, which are huge, and DPit = 45 - is that 45degree pitch back? Which is what it appeared to do.
Any more ideas why did it did what it did?
How can I gain some confidence that it's not going to do this again next time I switch to loiter?
Should I recalibrate everything? gyros, compass, etc. (I don't see how any of this could be that out given it was flying well in stabilize and alt hold)
Any ideas welcome.
PS: hope I've picked a sensible category.