Did you try the axis remapping feature written in datasheet chapter 3.4 on page 26?   For your application,  i will have the following recommand:  1. before testing, ask tester to stand for a while with arm down and keep arm straight position.  this will help to calibration the position  2. then user can move arm and you can read sensor data to calculate the relative position.  ... View more

Yes, i will take your suggestion to the engineer team.  Avtually we put following comment in our API on Github bno055_support.c This file shall be used as an user guidance, here you can find samples of * Initialize the sensor with I2C communication - Add your code to the I2C bus read and bus write functions. - Return value can be chosen by yourself - API just passes that value to your application code - Add your code to the delay function - Change I2C address accordingly in bno055.h ... View more