Logging Sensor Fusion for MMRL

We have a potential application where we need to log the Sensor Fusion Outputs for a 2 second dynamic event. Looking through the forums at https://mbientlab.com/community/discussion/comment/9951#Comment_9951 and https://mbientlab.com/community/discussion/comment/10279#Comment_10279 is there any way to log Quaternion, Linear Acceleration, and Corrected Gyro simultaneously for a 2 second interval?

What I don't follow is that I can stream these three items over BLE at the same time, which seems to imply that the mbientlab software has access to these signals to use as needed from Bosch's sensor fusion algorithm. What is the technical limitation to logging these items instead sending them over BLE?


    1. Only one output on sensor fusion can be streamed or logged at any time.
    2. BLE can stream only up to 100Hz at a time.
  • Thanks Laura! For point 1; what is physically preventing us from logging more than 1 fusion output? My team or I are happy to put in the work if it is something that can be fixed on the software side.

    1. Unfortunately we get the sensor fusion library from Bosch and it is hardcoded to do only one output at a time. It is completely out of our hands: https://www.bosch-sensortec.com/software-tools/software/sensor-fusion-software/
  • Ok; disappointing but understood. Next possibility; is there a way to have mbl_mw_datasignal_log log more than two signals? I can reliably get two loggers created but always get the "Could not create..." when doing more than two.

  • yes, you can log as many signals as you can as long as the output is allowed.

    You could log quaternions + gyroscope

    However, you should know that sensor fusion and its settings will always trump all other signals.

    Sensor fusion takes over the acc, mag, and gyro. If you logged quaternions + gyroscope, you could not alter the settings of the gyroscope, because the bosch sensor fusion has already hardcoded it to 100Hz.

    This is obviously not an issue if you did euler + temperature or euler + temperature + ambient light.

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