BNO055 pitch direction after startup (fusion mode)

[PragmaLab]

Hi all,

I'm using the BNO055 in fusion mode to detect pan (yaw) and tilt (pitch). Calibration is OK and also loading the calibration results at startup (in config mode) seems to be fine. The pitch readout is from 0 to 65535 and the 0 value is when levelled. That seems to be OK too. 

However, the direction of the pitch seems to be dependent on the position of the sensor when powering on. As the sensor leans forward at boottime, then pitch direction and range are different as when the sensors leans backwards at boottime. I added 2 images to make clear what exactly happens.

It is not 100% reproducable, but this problem makes it difficult(in fact: impossible) to use the BNO055 sensor to read tilt values.

Any hint? 

[o_o]

Hi Rob,

Thanks for the detailed explanation. I don't currently have a BNO055 with me, but I will test this in the coming days and report back.

However as a quick workaround, it seems like your issue is solved if you are not using the built-in axis remapping feature. Usually, when using quaternions, the axis remapping is superfluous, since you can easily multiply quaternions to combine their rotation. You can determine your desired frame of reference as a quaternion (does not have to be orthogonal) and simply multiply the quaternion output from the sensor to get it in your desired frame of reference.

o_o