Hi,
Had a weird one a couple of days ago, and I can't quite work out why my quad did what it did ...
Basically a nice warm sunny day (usually rare for Scotland, although not his year), hardly a blip of wind (max 0.9 m/s recorded) and just plugged in a quick and simple 6 waypoint mision (100m AGL, no delays) with auto take off and RTL.
First flight went almost perfect, except I had the geofence set in to close, so it got out to 150m and then returned, but as you can see it was a lovely straight flight.
I disconnected mission planner, switched to a fresh battery, re-connected mission planner and set the geofence out to 400m. I then attempted to re-run the same mission but got the below result ...
From take off the quad was lisiting to the left and started to circle, before I attempted an RTL (very briefly) and then got manual control. I added a bit too much throttle whilst trying to orientate and breached the upper failsafe (120m), so it took control and went for another mad (and fast) spinny circle, before I got control again and managed to get it more or less stable for a slightly bumpy landing (I bent one of the legs).
To me that looks like a problem with the compass, although compass MOT etc had all been completed succesfully (14%) and the last time I had an issue like this was pre firmware V3.1. Looking at the logs (see attached) the MAG values dont look too bad (at the start of the flight at least, before it started ramping up the speed whilst circling). GPS seemed fine (7-10 sats, HDOP ~2), vibes maybe a little out but not massive (can only see them on the T-log, as IMU was not on).
Now one thing I didn't do was re-load the mission before the second flight, and when querying the T-log (attached) it can't give me what its waypoints are. Plus if you re-play the T-log it does not show any waypoints (although querying the APM directly afterwards did give me the correct waypoints) ... this makes me think that something odd might have occured here, as though the APM was not quite configured, or in a bit of a limbo state or something?
Anyway, that is why I am a little stuck and just wondered if somone could take a peak at the logs to see if they can work out why it went nuts.
May thanks,
S.
Replies
Simon,
I suppose it's possible that the landrover had a strong magnetic field that yanked the heading around and then it didn't have enough time to recover once placed back down on the ground. Was the battery plugged in on the vehicle that whole time? I.e. was arducopter running? If 'yes' then maybe it's possible.
It had a heading, it's just that it was incorrect it seems. I've asked Jonathan Challinger if he can have a look at the compass numbers, he's got a script that can look at whether the heading is consistent with the GPS (i think).
Reloading the mission shouldn't be related at all but checking that the heading is correct with a handheld compass is a good check... although I never do it personally.
Hmm I thought it was turned on as I was viewing the camera screen via a laptop that was on the bonnet of the landrover (it was being beamed via 5.8 ghz from the quad), but I can't see movement from the take off point to the vehicle ... odd.
So I checked the previous log (the successfull flight) as I did the same thing there, and you can definetly see the quad moving away and being manipulated (whilst disarmed) but I can't see any obvious spikes in the mag field so I don't think it was that anyway.
I did a bit more diging in the log of the succesfull flight however and I have just seen this very odd thing ... it seems that right at the end of that flight (~5 mins before the flight that went nuts), the mag offsets (MOfsX/Y/Z) went huge for some reason. The log anaylsis says:
Test: Brownout = PASS -
Test: Compass = FAIL - Large compass offset in MAG data:Z: -27229.00
mag_field interference within limits (4.68%)
Test: Dupe Log Data = PASS -
Test: Empty = PASS -
Test: Event/Failsafe = WARN - FENCE
Test: GPS = PASS -
Test: Parameters = PASS -
Test: PM = PASS -
Test: Pitch/Roll = PASS -
Test: Underpowered = PASS -
Test: VCC = PASS -
Pretty sure that is not normal, and perhaps could have contributed to the following flight going weird? (see attached logs for the succesfull flight).
Thanks,
S.
2014-07-28 13-35-17.log
2014-07-28 13-26-54.tlog
Simon, I'd be very interested to see what you figure out.
I have the exact same issue, now to the point where I don't trust my compass on auto missions at all. It just seems to take off in the completely wrong direction, until the GPS finally kicks in and tells the APU that it's going the wrong way.
Now, every time I change the battery, I manually get it in the air and "calibrate" the compass by sending it to a few nearby guided points -- then just wait for it to figure out that it's going the wrong way. After a few, the compass seems to be calibrated, and I can send it on auto missions.
I contacted 3DRobotics support a while ago, but I never pulled the logs when this happens to be able to diagnose anything more.
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