WPILib Mecanum Drive, PID and drift

[SteveS]

Originally Posted by RufflesRidge

Source code can be found here (see the note on the project home page): https://usfirst.collab.net/sf/projects/wpilib/

One, often used, way of implementing a rotation PID using a gyro is to put it between the joystick and the rotation input of the RobotDrive mecanum method. Use the joystick to command changes in the angular setpoint and use the output of the PID as the rotation input of the mecanum drive method.

Thank you for the source code link!

As I understand the PIDController class, the output (Joystick class) must have a PIDOutput member or derived from that class. Joystick has neither. How would you implement that?

[FleventyFive]

Originally Posted by SteveS

As I understand the PIDController class, the output (Joystick class) must have a PIDOutput member or derived from that class. Joystick has neither. How would you implement that?

You could use the Gyro as the input for the PID loop, with Motors as the output, and use the Joystick to set the goal (setpoint) of the loop. It is kind of confusing because really each wheel would need its own PID controller, unless you create a PIDsubsystem which allows you to define what you do with the input and outputs.

My team also has drift when strafing and we're trying to correct it with PID loops using encoders as the input, but selecting gains, etc is difficult expecially if you do not have extended periods of time with the robot to test (because other people are working on it).

[SteveS]

Thanks to everyone for the help. We have some things to check out tomorrow.

[RufflesRidge]

Originally Posted by SteveS

As I understand the PIDController class, the output (Joystick class) must have a PIDOutput member or derived from that class. Joystick has neither. How would you implement that?

Create a class implementing PIDOutput that does what you want.