I would start here.
https://wpilib.screenstepslive.com/s...-mecanum-drive
Our team did our first mecanum over off season and found out that it was better to replace the "Get Z Axis" and "Get X Axis" and "Get Y Axis" with get raw axis with which ever ones you want. We put the X Axis to strafe left and right on axis 0 (left joystick X Axis). The Y Axis to go forwards and backwards on axis 1 (left joystick Y Axis). And for rotation, we put axis on the right X Axis on axis 4 (right joystick X Axis). Also make sure they your motor controllers are set up in the correct order when you set it up. Hopefully that helps some.
