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    Gyro offset: What does "slow and fast offset cancellation off" mean?

    Gyro offset: What does "slow and fast offset cancellation off" mean?

    ThomasBu
    Occasional Visitor

    Hi all,

    nearly all IMU datasheets give the gyro offset value with the restriction  "slow and fast offset cancellation off".

    What does that mean and moreover: What are the values if cancellation is turned on? Values for our BMI088 seem to be considerably smaller than values of above datasheet - but maybe cancellation is turned on.

    Hope that somebody knows where to find more.

    Thomas

    1 REPLY 1

    FAE_CA1
    Community Moderator
    Community Moderator

    Hi,

    Thanks for your inquiry.

    "Slow offset cancellation" or "Slow offset compensation" for accel and gyro means high-pass filter. This means that when IMU is not moving, both accel and gyro offsets will be around 0g or 0dps respectively. Some IMUs don't have high-pass filter inside. So there is no slow offset cancellation available in some IMUs.

    "Fast offset cancellation" or "Fast offset compensation" for accel and gyro means one-shot reference when IMU is stationary. All IMUs have this feature. For example, when the IMU is not moving, users can enable fast offset compensation to obtain the current zero-g offset for accel and zero-rate offset for gyro as references. Then the future measurements in data registers will remove these references automatically.

    Please see BMI055 datasheet at https://www.bosch-sensortec.com/media/boschsensortec/downloads/datasheets/bst-bmi055-ds000.pdf for more information about slow and fast offset compensation.

    In IMUs' datasheets the offsets for accel and gyro are from raw data or measurements without slow or fast offset cancellation turned on. BMI088 typical gyro zero-rate offset is +/-1dps which is smaller than other IMUs' +/-3dps gyro offset. This is because it is closed-loop gyro that has feedback circuit inside. The slow or fast offset cancellation is not turned on.

    Thanks.

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