navXDriveStraightPIDLoopOp.java

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package com.qualcomm.ftcrobotcontroller.opmodes;

import android.util.Log;

import com.kauailabs.navx.ftc.AHRS;
import com.kauailabs.navx.ftc.navXPIDController;
import com.qualcomm.robotcore.eventloop.opmode.OpMode;
import com.qualcomm.robotcore.hardware.DcMotor;
import com.qualcomm.robotcore.hardware.DcMotorController;
import com.qualcomm.robotcore.util.ElapsedTime;

import java.text.DecimalFormat;

/*
 * An example loop op mode where the robot will drive in
 * a straight line (where the driving direction is guided by
 * the Yaw angle from a navX-Model device).
 *
 * This example uses a simple PID controller configuration
 * with a P coefficient, and will likely need tuning in order
 * to achieve optimal performance.
 *
 * Note that for the best accuracy, a reasonably high update rate
 * for the navX-Model sensor should be used.  This example uses
 * the default update rate (50Hz), which may be lowered in order
 * to reduce the frequency of the updates to the drive system.
 */

public class navXDriveStraightPIDLoopOp extends OpMode {
    DcMotor leftMotor;
    DcMotor rightMotor;

    /* This is the port on the Core Device Interface Module        */
    /* in which the navX-Model Device is connected.  Modify this  */
    /* depending upon which I2C port you are using.               */
    private final int NAVX_DIM_I2C_PORT = 0;
    private AHRS navx_device;
    private navXPIDController yawPIDController;
    private ElapsedTime runtime = new ElapsedTime();

    private final byte NAVX_DEVICE_UPDATE_RATE_HZ = 50;

    private final double TARGET_ANGLE_DEGREES = 0.0;
    private final double TOLERANCE_DEGREES = 2.0;
    private final double MIN_MOTOR_OUTPUT_VALUE = -1.0;
    private final double MAX_MOTOR_OUTPUT_VALUE = 1.0;
    private final double YAW_PID_P = 0.005;
    private final double YAW_PID_I = 0.0;
    private final double YAW_PID_D = 0.0;

    private boolean calibration_complete = false;

    navXPIDController.PIDResult yawPIDResult;
    DecimalFormat df;

    @Override
    public void init() {
        leftMotor = hardwareMap.dcMotor.get("left_drive");
        rightMotor = hardwareMap.dcMotor.get("right_drive");

        navx_device = AHRS.getInstance(hardwareMap.deviceInterfaceModule.get("dim"),
                NAVX_DIM_I2C_PORT,
                AHRS.DeviceDataType.kProcessedData,
                NAVX_DEVICE_UPDATE_RATE_HZ);

        rightMotor.setDirection(DcMotor.Direction.REVERSE);

        /* If possible, use encoders when driving, as it results in more */
        /* predictable drive system response.                           */
        //leftMotor.setChannelMode(DcMotorController.RunMode.RUN_USING_ENCODERS);
        //rightMotor.setChannelMode(DcMotorController.RunMode.RUN_USING_ENCODERS);

        /* Create a PID Controller which uses the Yaw Angle as input. */
        yawPIDController = new navXPIDController( navx_device,
                navXPIDController.navXTimestampedDataSource.YAW);

        /* Configure the PID controller */
        yawPIDController.setSetpoint(TARGET_ANGLE_DEGREES);
        yawPIDController.setContinuous(true);
        yawPIDController.setOutputRange(MIN_MOTOR_OUTPUT_VALUE, MAX_MOTOR_OUTPUT_VALUE);
        yawPIDController.setTolerance(navXPIDController.ToleranceType.ABSOLUTE, TOLERANCE_DEGREES);
        yawPIDController.setPID(YAW_PID_P, YAW_PID_I, YAW_PID_D);
        yawPIDController.enable(true);

        df = new DecimalFormat("#.##");
    }

    public double limit(double a) {
        return Math.min(Math.max(a, MIN_MOTOR_OUTPUT_VALUE), MAX_MOTOR_OUTPUT_VALUE);
    }

    @Override
    public void start() {
        /* reset the navX-Model device yaw angle so that whatever direction */
        /* it is currently pointing will be zero degrees.                   */
        navx_device.zeroYaw();
        yawPIDResult = new navXPIDController.PIDResult();
    }

    @Override
    public void loop() {
        if ( !calibration_complete ) {
            /* navX-Micro Calibration completes automatically ~15 seconds after it is
            powered on, as long as the device is still.  To handle the case where the
            navX-Micro has not been able to calibrate successfully, hold off using
            the navX-Micro Yaw value until calibration is complete.
             */
            calibration_complete = !navx_device.isCalibrating();
            if ( calibration_complete ) {
                navx_device.zeroYaw();
            } else {
                telemetry.addData("navX-Micro", "Startup Calibration in Progress");
            }
        } else {
            /* Wait for new Yaw PID output values, then update the motors
               with the new PID value with each new output value.
             */

            /* Drive straight forward at 1/2 of full drive speed */
            double drive_speed = 0.5;

            if (yawPIDController.isNewUpdateAvailable(yawPIDResult)) {
                if (yawPIDResult.isOnTarget()) {
                    leftMotor.setPower(drive_speed);
                    rightMotor.setPower(drive_speed);
                    telemetry.addData("Motor Output", df.format(drive_speed) + ", " +
                            df.format(drive_speed));
                } else {
                    double output = yawPIDResult.getOutput();
                    leftMotor.setPower(limit(drive_speed + output));
                    rightMotor.setPower(limit(drive_speed - output));
                    telemetry.addData("Motor Output", df.format(limit(drive_speed + output)) + ", " +
                            df.format(limit(drive_speed - output)));
                }
            } else {
                /* No sensor update has been received since the last time  */
                /* the loop() function was invoked.  Therefore, there's no */
                /* need to update the motors at this time.                 */
            }
            telemetry.addData("Yaw", df.format(navx_device.getYaw()));
        }
    }

    @Override
    public void stop() {
        navx_device.close();
    }
}