BHI160B sudden jumps in quaternion

[soroush]

Dear Bosch community,

We are performing some tests with BHI160B, and occasionally we observe sudden jumps in quaternion elements.

A CSV file of the log and a few screenshots are attached.

We are using the "Bosch_PCB_7183_di03_BMI160-7183_di03.2.1.11824" firmware and the provided c driver (https://github.com/BoschSensortec/BHy1_driver_and_MCU_solution/blob/master/examples/rotation_vector_...) with some modifications:

• 100Hz sampling rate
• Sensor mounted vertically with proper remapping matrix 

Any advice would be highly appreciated.

[BSTRobin]

Hi soroush,

You need to run the calibration code https://github.com/BoschSensortec/BHy1_driver_and_MCU_solution/blob/master/examples/calib_profile_ex... until game rotation vector's accuracy reaches 3 before testing.

[soroush]

Hi BSTRobin,

We warm start standalone BHI160B (uploading Acc/Gyro biases from the previous calibration process) and freshly perform stationary plus 6-face calibration before any test according to the same code you referred to, and GRV's accuracy always remains zero. To our understanding, calibration profile accuracy elements are the same as Acc's and Gyro's accuracies, however, we check all to be 3 before motion tests. 
The official datasheet on the website (Although incomplete!!!!) mentions on page 60 that the GRV's accuracy is reported as zero (screenshot attached). Have you seen any value except 0 for GRV's accuracy?  RV's or Geo-RV's accuracies might be different. 

[BSTRobin]

Hi soroush,

Data sheet description means accuracy game rotation vector accuracy is 0 if you see it from callback function of virtual sensor.
But you could get accel, gyro, mag physical sensor accuracy from example code: https://github.com/boschsensortec/BHy1_driver_and_MCU_solution/blob/master/examples/calib_profile_ex...
do_calibrate:
...

[JAS]

Hi @soroush 

I know this was 2 years ago, but just wondering if you ever resolved the issue with IMU experiencing discontinuities in quaternion results for the game vector and rotation vector? I am having similar issues with the BHI360, and am wondering what the next steps should be...

[soroush]

Hi JAS,
We did not find any solution for that, and gave up!
It is bad that BHI360 also has that issue!!!