CIT 128 - NXT Lego Mindstorms Wall Follower Project

/*

    Author(s): Robert A. Petersen and Esteban Tina
    Assignment:  Project #7 --- Wall Follower Robot
    Date: April 8, 2015
    Description:  Program NXT Robot to follow wall, if touch sensor is triggered the robot will back up, and continue following wall.
*/

import lejos.nxt.*;
import lejos.robotics.navigation.DifferentialPilot;
import lejos.util.Stopwatch;

public class Project7 implements ButtonListener // Make sure the classname matches the filename (case-sensitive)
{
    private DifferentialPilot bot; // Field declaration for a Pilot object

    //the code in the main method will not change (except for the classname)
    public static void main(String[] args)
    {

        Project7 myProgram = new Project7(); // Matches classname (case-sensitive)
        Button.ESCAPE.addButtonListener(myProgram); // Register this object as a listener
        myProgram.run();

    } // main()

    /*

        The constructor generally instantiates field objects and
        sets other initial state information

    */
    public Project7()   //matches classname (case-sensitive)
    {

        bot = new DifferentialPilot(56, 108, Motor.B, Motor.C); // Instantiate a Pilot object named "bot"

    } //constructor

    /*

        Your code goes in this method

    */
    public void run()
    {

        // Create a TouchSensor that monitors sensor port S1
        TouchSensor touch = new TouchSensor(SensorPort.S1);

        // Create a Stopwatch that monitors elapsed time in milliseconds
        Stopwatch sw = new Stopwatch();

        /*
            Create your variables here.
            Call pause() to allow time to get your finger off the button.
        */
        pause(3000);
        // Reset the stop watch to 0, before entering the loop
        sw.reset();

        /*
            Set the stop watch to run for some amount of time.

                10  seconds = 10000 milliseconds  (10 seconds)
                30  seconds = 30000 milliseconds  (1/2 minute)
                60  seconds = 60000 milliseconds  (1 minute)
                120 seconds = 120000 milliseconds (2 minutes)
                180 seconds = 180000 milliseconds (3 minutes)
                etc.
        */

        long time_in_milliseconds = 10000L;

        while ( sw.elapsed() < 20000 )
        {
            bot.forward (); // Send the robot forward

            if (touch.isPressed())
            {
        bot.travel(-100);
                bot.rotate(-15);
            } // if

        } // while

    } // run()

    /*

        The following method writes a string to the screen. Useful for debugging.

    */
    public void displayString(String msg)
    {

        LCD.clear();
        LCD.drawString(msg, 0, 0); //writes the msg to the screen
        LCD.refresh();

    } // displayString()

    /*

        The following method writes an int (whole number) to the screen.
        Useful for debugging.

    */
    public void displayInt(int num)
    {

        LCD.clear();
        LCD.drawInt(num, 4, 0, 0); //writes the num to the screen
        LCD.refresh();

    } // displayInt()

    /*

        The following method allows the bot to do what it was doing,
        but suspends execution of the next statement.

        When this method returns, the program continues executing
        where it left off.

    */
    public void pause(int milli)
    {

        try
        {
            Thread.sleep(milli);
        } // try

        catch(InterruptedException e)
        {
        } // catch

    } // pause()

    /*

        This method is required when a class is a ButtonListener
        it responds to the action of the button being pressed.

    */
    public void buttonPressed(Button b)
    {
        displayString("btn pressed");
        bot.stop();
    }

    /*

        This is also required, but we aren't using it, so it is empty.

    */
    public void buttonReleased(Button b)
    {

        // Empty method

    } // buttonReleased()

} // class Project7