Pixhawk in Loiter mode going right and backwards


I recently took my copter for a flight. I was able to takeoff smoothly but it hovers to the right and backwards. It was hard to fly back the drone since I had to go all the way to the left to bring it stable. There is no PID control implemented and my trimming is set to default.

I have attached my bin file as well so that you guys can have a better understanding.

00000308.zip (703.7 KB)

check your transmitter trims, it seems rc1 and rc2 are not center.

I will check that and let you know right away. I auto analyzed my log and this is the output:

Log File C:\Users\Admin\AppData\Local\Temp\tmpA7EB.tmp.log
Size (kb) 2894.466796875
No of lines 35119
Duration 0:05:12
Vehicletype ArduCopter
Firmware Version V3.6.11
Firmware Hash f0d59294
Hardware Type
Free Mem 0
Skipped Lines 0
Test: Autotune = UNKNOWN - No ATUN log data
Test: Brownout = GOOD -
Test: Compass = FAIL - Large change in mag_field (54.22%)
Max mag field length (635.04) > recommended (550.00)

Test: Dupe Log Data = GOOD -
Test: Empty = GOOD -
Test: Event/Failsafe = FAIL - ERR found: CRASH
Test: GPS = GOOD -
Test: IMU Mismatch = GOOD - (Mismatch: 0.47, WARN: 0.75, FAIL: 1.50)
Test: Motor Balance = GOOD - Motor channel averages = [1382, 1454, 1419, 1384]
Average motor output = 1409
Difference between min and max motor averages = 72
Test: NaNs = FAIL - Found NaN in CTUN.TAlt
Found NaN in CTUN.DSAlt

Test: OpticalFlow = FAIL - FAIL: no optical flow data

Test: Parameters = FAIL - ‘THR_MIN’ not found
Test: PM = GOOD -
Test: Pitch/Roll = UNKNOWN - ‘BarAlt’
Test: Thrust = GOOD -
Test: VCC = UNKNOWN - No CURR log data

It says “Compass = FAIL - Large change in mag_field (54.22%)
Max mag field length (635.04) > recommended (550.00)”. How do I resolve this?

Hi all, this issue is solved but still a mystery. All I did was re-calibrate the transmitter and all was OK.

This seems to be happening a lot to our drones. It’s either the transmitter (horus 10x) or the dragon link which is a constant source of problems too.

At any rate if you see it then try transmitter calibration.

Yes, it was actually the trimming issue on my transmitter. But my log says “Compass = FAIL - Large change in mag_field (54.22%)
Max mag field length (635.04) > recommended (550.00)”.

What could be the reason? How do I resolve this?

Dragonlink is a hobbist crap with good hype. No surprise it causes issues. for long range you should change to RFDesign x series.

Moving compass away from power wires and/or motors, batteries.

If you’re talking about the GPS then I’ve placed it on a GPS stand off. And I am using Turnigy 9x transmitter in my copter,

Longer standoff or ignore it if you are not getting error messages in the log. Not the near useless Auto Analysis but a proper .bin log file.

We have changed to rfd for this reason.

Are you using a here2? If so they are off by 17 d Degrees ish, you should run 4.0.00 or higher and set the compass scale factor to 1.17

I think that may solve your issue