Servers by jDrones

Bad AHRS all the time

Continually getting Bad AHRS - with Rover 4 and Pixhawk 2.1. Been calibrated many times but shows slight jumping on horizon continually. Any ideas?

Post a log, and keep high current wires away from your compass.

1 Like

No high current cables near. Does it with only usb, battery and gps connected all laid on floor with battery and power cables running directly away. Showing 12 Sats and steady position. Seems to be in vertical plane where ardupilot thinks jitter occuring - obviously no movement happening. I’ll post a log as soon as I can, weather permitting.

@pilotltd, the “Bad AHRS” message isn’t great, it actually means that the vehicle doesn’t have a good GPS lock. It’s nothing more serious than that. I’m planning to remove this message in a future version. It’s slightly scary and there’s probably nothing really wrong.


It is a scary message :slight_smile: 12 sats in view but that implies I don’t have a good lock but GPS 3D message shows in HUD screen and map correctly shows my position. It does however drift around my actual position slightly over time but only a few metres at most. What are the requirements for a good lock? Is positional averaging performed within the software, or is it just using raw readings?


ArduPilot has a sophisticated Extended Kalman Filter (EKF) which combines the GPS with other sensors including gyros, accels and barometer.

The “Bad AHRS” message will go away once the EKF is happy the various sensors are consistent with each other. My guess is that even though there are 12 satellites, it’s still not enough or they’re not providing good readings.

Maybe it would be best to post a dataflash log.

Servers by jDrones