If anyone has been experiencing incorrect or large margins of error with their VEX IQ (2nd gen) Brains, more specifically with the Inertial Sensor, we have an article to help!
Troubleshooting the VEX IQ (2nd gen) Inertial Sensor using Deep Calibration
Calibrating the VEX IQ (2nd gen) Inertial Sensor can sometimes result in an incorrect calibration, where the heading and rotation readings are inaccurate by a noticeable degree. In order to obtain the correct readings, the Inertial Sensor will need to be deep calibrated.
For example, your Inertial Sensor will need deeply calibrated if: when the Brain is rotated 360 degrees, the Inertial Sensor will report a 357 degree heading and rotation. You’ll notice this is more than approximately half of a degree margin of error. Anything more than one degree should be deeply calibrated.
Deeply calibrating the Inertial Sensor can help to minimize this error. Let me know if you find this article helpful 
