Got Gyro drift? Try Sensor Fusion !

[Richard100]

Steve - To conduct the calibration, you want to run 'Live', i.e. using a run-button deploy / debug mode, rather than compiling and deploying code to the roboRIO. This simply allows you to interact with the Dialog boxes that I use to prompt the calibration process (if you try to run the code as deployed when MagCal is TRUE then the program will appear to hang while it waits for you to respond to a Dialog box that, well, isn't displayed anywhere). Yes, you request magnetometer calibration by setting MagCal in IMUOpen to TRUE. Whether you use the Demo Project, or move the IMU code within Demo into your robot code, doesn't matter.

To use the IMU on the robot, it is also important that the calibration be performed with the sensor installed, to ensure the robot hard iron effects are compensated for during the calibration process. If you move the sensor, or change the metallic configuration of the robot, a re-calibration is strongly recommended.

The general idea is to set MagCal to TRUE to perform the cal, run the code, execute the cal, practicing the process until you get a good result (referring to the Example Magnetometer Cal Plot), then stop the code. Copy the four resulting magnetic calibration values (Scale & Zero for both X & Y) listed under Magnetometer Cal Results on the IMUOpen Front Panel, to the corresponding Mag Set control input for the same VI. Save this and reconfigure MagCal to FALSE. Now when you run the code (which doesn't need to be 'Live' anymore) the IMU is fully calibrated and you can use the sensor fusion results from the Complementary Filter VI.

Adjust tau mag and tau acc to taste, to balance the fusion.

Some teams (I believe GaCo was one) only used the IMU and this software for it's gyro readings, which is fine if you don't need the benefit of sensor fusion. This still gives you a three-axis digital gyro. In this case, the magnetometer calibration is not required, and you would read your gyro results directly from the IMURead VI. The IMUZeroBias VI provides the circular buffer to constantly calibrate the Gyro while the robot is disabled, which can be useful in mitigating measurement drift.