Page 85 - The Definitive Guide to Building Java Robots

Preston_5564C03.fm Page 66 Wednesday, October 5, 2005 7:21 AM

66 CHAPTER 3 ■ MOTION

■Note I have found that using millisecond resolution is just as accurate as wheel encoders over short
distances (<3 meters or <10 seconds). This is because the wheel slippage and time to stop accuracies are
at their low end with these distances and speeds. But even these shortcomings are overcome by distance
measurement sensors so as to eliminate the “practical” need for wheel encoders.

Example 3-7. TimedDiffDrive.java

package com.scottpreston.javarobot.chapter3;
import com.scottpreston.javarobot.chapter2.JSerialPort;
import com.scottpreston.javarobot.chapter2.SingleSerialPort;
import com.scottpreston.javarobot.chapter2.Utils;
public class TimedDiffDrive extends BasicDiffDrive {

// construct with JSerialPort
public TimedDiffDrive(JSerialPort serialPort) throws Exception {
super(serialPort);
}

// forward
public void forward(long ms) throws Exception {
// calls super
forward();
// pause
Utils.pause(ms);
// stop
stop();
}

// reverse
public void reverse(long ms) throws Exception {
reverse();
Utils.pause(ms);
stop();
}
// pivot left
public void pivotLeft(long ms) throws Exception {
pivotLeft();
Utils.pause(ms);
stop();
}

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