[uutzinger]

The results with the IMU attached to CIM motor is very impressive.

Since all IMUs discussed in this thread are MEMS devices they all have same basic limitations such as drift and need for calibration.

Using a fusion algorithm that includes a compass will make the IMU stable over very long periods of time because the orientation is defined by gravity and earth's magnetic field and those two vectors are not going to change if one does not move the IMU.

Unfortunately in most buildings there are magnetic anomalies that change over the course of a basketball field. Also any motor that is about a foot from the sensor will affect the compass.

Most gyroscopes that are based on MEMS devices can not measure the earth's rotation because their noise is to high and their drift is too large.

To overcome these limits, run time calibration for the gyroscope bias and magnetic field anomaly detection is needed for the compass which is the key ingredient of the software.

Based on your report, the firmware in the BNO055 must be of very good quality.