Negated gravity on subset of BMI270 and IMU alignment question #141

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MrUnknownDE · 2026-04-05T17:51:58+02:00

MrUnknownDE commented

2026-04-05 17:51:58 +02:00

Originally created by @kmatzen on 2/1/2025

I assembled 6 trackers according to the instructions for BMI270. Four of them can be calibrated on a table. The other two report that the acceleration of about 10 is greater than -7.5. If I flip these units upside down, the calibration will continue. Has anyone encountered this? Would it be safe to modify the code to ensure the norm of the acceleration vector is near 9.8?

I purchased my BMI270's from here. https://store.kouno.xyz/products/bmi270-breakout-board

I also have a related question on IMU alignment. Why does the firmware need to know the orientation of the IMU inside the tracker, i.e., the IMU_ROTATION macro? Does the one time table calibration and the occasional pose reset not give it the information it needs?

*Originally created by @kmatzen on 2/1/2025* I assembled 6 trackers according to the instructions for BMI270. Four of them can be calibrated on a table. The other two report that the acceleration of about 10 is greater than -7.5. If I flip these units upside down, the calibration will continue. Has anyone encountered this? Would it be safe to modify the code to ensure the norm of the acceleration vector is near 9.8? I purchased my BMI270's from here. https://store.kouno.xyz/products/bmi270-breakout-board I also have a related question on IMU alignment. Why does the firmware need to know the orientation of the IMU inside the tracker, i.e., the IMU_ROTATION macro? Does the one time table calibration and the occasional pose reset not give it the information it needs?

MrUnknownDE closed this issue

2026-04-05 17:51:58 +02:00

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Reference: github/SlimeVR-Tracker-ESP#141