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    Why am I not getting good readings from the BNO055?

    Why am I not getting good readings from the BNO055?

    rvillagrasa
    New Poster

    Hello. I an using the 9 Axis Motion Shield in an autoguided vehicle. I have already performed the calibration process and stored the appropiate settings in the Arduino EEPROM. When I turn the device on, I copy the previously stored settings in the calibration registers and, after that, I put the sensor in IMU mode (only accelerometer and gyroscope). I don't know if any step I do is wrong, but when I place the sensor in my hand, the Heading angle I read is correct, but when it is mounted on the vehicle is wrong. What could be happening?

    13 REPLIES 13

    BSTRobin
    Community Moderator
    Community Moderator

    Hello rvillagrasa,

    This would happen for BNO055. Because the situation on the vehicle is more complicated than on hand. If I rotate the BNO055 randomly, and then goes back to the original position, the yaw angle would differs from the beginning for more than 10 deg.

    And the rotation rate on hand should be different from that on vehicle. For example, it may takes 1 second to rotate the BNO055 360 degree on hand, but it may takes around 10 seconds for the vehicle to rotate 360 degrees. And for gyro, long time means large bias integration. So the yaw angle bias on the vehicle is larger.

    And the vibration on the vehicle should also be larger that on hand. That would be another main factor.

    We still recommend to use NDOF mode for BNO055 to get yaw angle.

    Thank you for your reply. I would want to use NDOF mode, but with this mode I have checked that calibration of magnetometer is lost quickly and value of the yaw angle changes abruptly when sensor doesn't find the magnetic north. Also, there is a lot of electrical noise around the sensor and I suppose that it affects the magnetometer.

    BSTRobin
    Community Moderator
    Community Moderator

    Hello rvillagrasa,

    If the actual magnetic interference is too large, it will indeed affect the accuracy.

    Also to the accelerometer and gyroscope measurements? If I don't use the magnetometer in IMUPLUS mode, magnetic interference will affect the accuracy?

    BSTRobin
    Community Moderator
    Community Moderator

    Hello rvillagrasa,

    If you use IMU mode only, magnetic interference will not affect the accuracy, but slow movement will affect the accuracy.

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