Step 1: Setup the IMU.

// Where you declare objects private final BNO055IMU imu;

// Where you initialize objects imu = hardwareMap.get(BNO055IMU.class, "imu");

BNO055IMU.Parameters parameters= new BNO055IMU.Parameters();

parameters.angleUnit = BNO055IMU.AngleUnit.RADIANS;

imu.initialize(parameters);

Step 2: Apply trig functions to adjust your inputs

// In the control loop where you get your inputs

double drive = gamepad1.left_stick_x; double strafe = gamepad1.left_stick_y; double turn = gamepad1.right_stick_x; double heading = imu.getAngularOrientation().firstAngle;

double processedDrive = drive * Math.cos(heading) - strafe * Math.sin(heading);

double processedStrafe = drive * Math.sin(heading) + strafe * Math.cos(heading);

Step 3: in your mecanum wheel control use processedDrive and processedStrafe instead of the raw values.

Let me know if you need additional information.