Yaw Error Estimate on PX4v1.15

ndwe

Hi,
We are using fc-v2 with the ModalAI 4-in-1 ESC (M0138) and a 3DR M10 ublox gps unit.

The fc-v2 was shipped with px4 v1.15. The system works well but there is a pre-flight check fail that we are trying to clear.

PREFLIGHT FAIL: EKF YAW ERROR

Care has been taken to calibrate the sensors but we are unable avoid this.

The solution has been to sway the drone side to side and then the error clears and the drone is 'Ready to fly". Because of our use case this is not a practical approach.

The drone is for outdoor use and needs GPS.

Any advise on how to fix this issue would be greatly appreciated.

Cheers

Eric Katzfey

@ndwe I would first try upgrading to v1.16.1 and see if the issue persists. Some other ideas: make sure EKF2_MAG_DECL is set properly for your area, try setting EKF2_MAG_TYPE to 1, and / or increase COM_ARM_EKF_YAW to a higher value (like 0.7).

Eric Katzfey

@ndwe You could also ask on the PX4 forum to see what ideas the PX4 community has on this issue.

ndwe

@Eric-Katzfey Hi, thanks for the response.

EKF2_MAG_DECL - yes, set to Sydney, Australia
COM_ARM_EKF_YAW is set to the max 1.0 - the value it is reading is 3.5+
Wouldn't changing EKF2_MAG_TYPE to 1 mean that the compass isn't used during flight and rely solely on GPS for heading, but I can ask px4 community this.

Moving to px4 v1.16 the error changes to X/Y position control error, but the fix is the same.

A question on px4 firmware versions. ModalAI develops on px4 v.14.
The latest being modalai_fc-v2_1.14.0-2.0.133.px4

When I install this firmware the error isn't present and (Ready to fly) arming can occur on the ground without having to move the drone to fix the yaw error. Would you recommend using this version on a non-voxl system, we are using a Jetson? We are interested to know if there is a reason why this version works with your hardware but not later versions of px4?

Thanks again