No EKF2 Config Produces Stable Altitude

[brandon]

Platform: Starling 2 Max (M0054 / MRB-D0012)
Software: voxl-suite 1.5.0, system-image 1.8.04, PX4 1.14.0

We've tested 3 Modal AI EKF2 helper configs across 15+ outdoor flights on Starling 2 Max. VIO+GPS causes yaw-reset and crashes. GPS with baro height ref reports negative altitude. GPS with GPS height ref balloons. None produce stable altitude. We need reliable altitude for autonomous precision landing on a containerized system. What config do other operators use?

Reference logs:

• GPS+baro height ref: https://review.px4.io/plot_app?log=55f037ae-36d2-4ce1-bbd6-919ddc6da630. Negative altitude while clearly airborne, unstable vertical velocity
• GPS+GPS height ref: https://review.px4.io/plot_app?log=fd7a0bba-991c-44fe-95e7-238caeda5c5f. Altitude ballooning, floating around in safety pilot joystick control. Best example showing altitude instability over an extended period.
• GPS+GPS height ref: https://review.px4.io/plot_app?log=5f1ae22c-d6a5-4963-a57d-3970c9d34e5b. Best example of successful flight yet, but still has significant altitude issues.

We've tried the ekf2_universal_tweaks.params file as well as the outdoor_gps.params and outdoor_gps_baro.params files. When using the barometer we've also applied the exposed_baro.params file. We've recalibrated the barometer using the VOXL web portal. We've run IMU calibration repeatedly both in QGC and the terminal interface in VOXL. We also tried upgrading the SDK to 1.6.3 on one of our test drones.

We have many more logs but this is the best scattering of what we've been struggling with. Please help, thank you.

Sentien Robotics.

[brandon]

@brandon said in No EKF2 Config Produces Stable Altitude:

Platform: Starling 2 Max (M0054 / MRB-D0012)
Software: voxl-suite 1.5.0, system-image 1.8.04, PX4 1.14.0

We've tested 3 Modal AI EKF2 helper configs across 15+ outdoor flights on Starling 2 Max. VIO+GPS causes yaw-reset and crashes. GPS with baro height ref reports negative altitude. GPS with GPS height ref balloons. None produce stable altitude. We need reliable altitude for autonomous precision landing on a containerized system. What config do other operators use?

Reference logs:

• GPS+baro height ref: https://review.px4.io/plot_app?log=55f037ae-36d2-4ce1-bbd6-919ddc6da630. Negative altitude while clearly airborne, unstable vertical velocity
• GPS+GPS height ref: https://review.px4.io/plot_app?log=fd7a0bba-991c-44fe-95e7-238caeda5c5f. Altitude ballooning, floating around in safety pilot joystick control. Best example showing altitude instability over an extended period.
• GPS+GPS height ref: https://review.px4.io/plot_app?log=5f1ae22c-d6a5-4963-a57d-3970c9d34e5b. Best example of successful flight yet, but still has significant altitude issues.

We've tried the ekf2_universal_tweaks.params file as well as the outdoor_gps.params and outdoor_gps_baro.params files. When using the barometer we've also applied the exposed_baro.params file. We've recalibrated the barometer using the VOXL web portal. We've run IMU calibration repeatedly both in QGC and the terminal interface in VOXL. We also tried upgrading the SDK to 1.6.3 on one of our test drones.

We have many more logs but this is the best scattering of what we've been struggling with. Please help, thank you.

Sentien Robotics.

following up on this

[Moderator]

@brandon there are likely a number of things going on

If the drone sits idle for a period of time, the sensors heat up (accel and baro). When the props start spinning, the temperature drops causing significant drift. If you let the props spin for 10 or 20s cooling off the board, that can help

I would guess after 30-60s of flight, the altitude stabilizes. That is the temperature of the sensors stabilizng.

The latest SDKs have temperature compensated calibration for IMU and baro. Try calibrating accel and baro and see if that helps.
https://docs.modalai.com/calibrate-baro/
https://docs.modalai.com/calibrate-imu/

The GPS on Starling 2 Max has been tricky. We do have a new GPS on the way that looks promising, and hope to make it available in the next 2mo.