[geel9]

Hey,

We're trying to get our PID loops to control the motors' rate, as opposed to their distance.

Here is our code:

//Initializes the motors.
    private final SpeedController left = new Jaguar(1);
    private final SpeedController right = new Jaguar(2);
    
    //Initializes the Encoders.
    private final Encoder leftEncoder = new Encoder(1, 2);
    private final Encoder rightEncoder = new Encoder(3, 4);
    
    //Proportional, Integral, and Dervative constants.
    //These values will need to be tuned for your robot.
    private final double Kp = 0.1;
    private final double Ki = 0.001;
    private final double Kd = 0;
    
    //This must be fully initialized in the constructor, after the settings
    //for the encoders have been done.
    private final PIDController leftPID;
    private final PIDController rightPID;

    public PIDDrive() {
        //Sets the distance per pulse in inches.
        leftEncoder.setDistancePerPulse(-1);
        rightEncoder.setDistancePerPulse(-1);

        
        //Starts the encoders.
        leftEncoder.start();
        rightEncoder.start();
        
        //Sets the encoders to use distance for PID.
        //If this is not done, the robot may not go anywhere.
        //It is also possible to use rate, by changing kDistance to kRate.
        leftEncoder.setPIDSourceParameter(Encoder.PIDSourceParameter.kRate);
        rightEncoder.setPIDSourceParameter(Encoder.PIDSourceParameter.kRate);
        
        //Initializes the PID Controllers
        leftPID = new PIDController(Kp, Ki, Kd, leftEncoder, left);
        rightPID = new PIDController(Kp, Ki, Kd, rightEncoder, right);
        
        leftPID.setPercentTolerance(25);
        rightPID.setPercentTolerance(25);
        
        leftPID.setContinuous();
        rightPID.setContinuous();
        
        //Enables the PID Controllers.
        leftPID.enable();
        rightPID.enable();
        

    }

    public static void WriteDriverStationLine(DriverStationLCD.Line line, String text){
        DriverStationLCD.getInstance().println(line, 1, text);
        DriverStationLCD.getInstance().updateLCD();
    }
    /**
     * This function is called once each time the robot enters operator control.
     * Teleop commands are put in here
     */
    public void operatorControl() {
        leftPID.setSetpoint(1000);
        rightPID.setSetpoint(1000);
        
        while(isOperatorControl()){
            
            WriteDriverStationLine(DriverStationLCD.Line.kUser1, "E: " + leftPID.getError());
            WriteDriverStationLine(DriverStationLCD.Line.kUser2, "E2: " + rightPID.getError());
            WriteDriverStationLine(DriverStationLCD.Line.kUser3, "D: " + leftEncoder.getRate());
            WriteDriverStationLine(DriverStationLCD.Line.kUser4, "D2: " + rightEncoder.getRate());
        }

The wheels spin forward, then rapidly switch directions.