Quad slowly drifts left and continuously yaws left in Loiter mode

ArduCopter Copter 4.6
1

Hi everyone,

I am facing an issue with my quadcopter in Loiter mode and would appreciate some guidance on where I should start troubleshooting.

Problem

The quad is able to maintain its altitude very well in Loiter. However, it has two simultaneous issues:

  1. It slowly drifts towards the left side even though the sticks are centered.
  2. At the same time, the quad slowly yaws towards the left, approximately in increments of 1°.

The yaw is not a sudden or aggressive rotation. It is a slow, continuous leftward yaw while the vehicle is trying to hold position.

Interestingly, the altitude hold is very good, and there is no significant up/down oscillation.

Hardware configuration

  • Flight Controller: Cube Orange Plus
  • Frame: Quad X
  • Motors: T-Motor MN7005 KV115
  • ESCs: T-Motor Flame 60A V2.0
  • Propellers: 24 inch
  • Battery: 2 × GenX Pro Solid State 6S 21 Ah connected in series
  • Battery: 12S, 50.4 V fully charged
  • AUW: approximately 7 kg
  • Flight Mode: Loiter

Note: Calibrated compass in good GPS 3D fix , tested MOT compass interference (1%), aligned motors in level.

Observations

The vehicle does not appear to have an altitude-control problem. It maintains its altitude quite well.

The main concern is the combination of:

Slow leftward position drift + slow continuous left yaw.

The drift appears to happen even when there is no intentional stick input.

I have already followed the ArduPilot Mandatory Hardware Checks (AMC) as much as possible.

However, I had previously disabled the pre-arm checks for testing purposes. I will be enabling the pre-arm checks again before further testing.

2

You have RC input exceeding deadzone for ROLL and YAW (according to Your params, gray area is about to be no RC input)

obraz
obraz961×568 10.9 KB

Calibrate radio (on Your transmitter, reset trims if used) then calibrate radio in arducopter using mission planner.

3

Thanks for the analysis.

I performed radio calibration and did a test flight , but now the quad is automatically yawing towards right ,but its not getting drifted now

i am attaching the log , kindly let me know if this is related to any other parameter issue or structural issue

thanks!

4

obraz
obraz1737×690 71.1 KB

Word of explanation - You RC channel values has to be in range of TRIM ± DZ. So… It looks like Yaw channels is outside of this zone and this is considered as non zero yaw input.

Not sure what kind of radio You use, but You did not calibrate it very well or did not calibrate rc inputs in mission planer, or radio is a bit crappy and can not hold center value very well, or centering spring is not strong enough.

Easy fix is to increase DZ value, to keep whatever value RC4 has inside dead zone. Move stick left, then release and see channel value, move to right, release and see channel value.

make middle value of that as TRIM value, and difference between readins Your dead zone (technically half od this difference, but You want/need some margin I guess).