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Twisted eric
04-02-2011, 20:00
:confused: I'm using the base code they give us I have a problem it takes the the right sensor and the middle sensor to go completely strait

package edu.wpi.first.wpilibj.templates;

import edu.wpi.first.wpilibj.DigitalInput;
import edu.wpi.first.wpilibj.DriverStation;
import edu.wpi.first.wpilibj.RobotDrive;
import edu.wpi.first.wpilibj.SimpleRobot;
import edu.wpi.first.wpilibj.Timer;


public class LineTracker extends SimpleRobot {

RobotDrive drive; // robot drive base object
DigitalInput left; // digital inputs for line tracking sensors
DigitalInput middle;
DigitalInput right;
DriverStation ds; // driver station object for getting selections
double defaultSteeringGain = 0.70; // the default value for the steering gain

public LineTracker() {
drive = new RobotDrive(1, 2);

// set the MotorSafety expiration timer
drive.setExpiration(15);

// create the digital input objects to read from the sensors
left = new DigitalInput(1);
middle = new DigitalInput(2);
right = new DigitalInput(3);

// get the driver station instance to read the digital I/O pins
ds = DriverStation.getInstance();
}


public void autonomous() {

int binaryValue; // a single binary value of the three line tracking
// sensors
int previousValue = 0; // the binary value from the previous loop
double steeringGain; // the amount of steering correction to apply

// the power profiles for the straight and forked robot path. They are
// different to let the robot drive more slowly as the robot approaches
// the fork on the forked line case.


double forkProfile[] = {0.70, 0.70, 0.55, 0.60, 0.60, 0.50, 0.40, 0.00};
double straightProfile[] = {0.7, 0.7, 0.6, 0.6, 0.35, 0.35, 0.35, 0.0};

double powerProfile[]; // the selected power profile

// set the straightLine and left-right variables depending on chosen path
boolean straightLine = ds.getDigitalIn(1);
powerProfile = (straightLine) ? straightProfile : forkProfile;
double stopTime = (straightLine) ? 2.0 : 4.0; // when the robot should look for end
boolean goLeft = !ds.getDigitalIn(2) && !straightLine;
System.out.println("StraightLine: " + straightLine);
System.out.println("GoingLeft: " + goLeft);


boolean atCross = false; // if robot has arrived at end

// time the path over the line
Timer timer = new Timer();
timer.start();
timer.reset();

int oldTimeInSeconds = -1;
double time;
double speed, turn;

// loop until robot reaches "T" at end or 8 seconds has past
while ((time = timer.get()) < 8.0 && !atCross) {
int timeInSeconds = (int) time;
// read the sensors
int leftValue = left.get() ? 1 : 0;
int middleValue = middle.get() ? 1 : 0;
int rightValue = right.get() ? 1 : 0;
// compute the single value from the 3 sensors. Notice that the bits
// for the outside sensors are flipped depending on left or right
// fork. Also the sign of the steering direction is different for left/right.
if (goLeft) {
binaryValue = leftValue * 4 + middleValue * 2 + rightValue;
steeringGain = defaultSteeringGain;
} else {
binaryValue = rightValue * 4 + middleValue * 2 + leftValue;
steeringGain = defaultSteeringGain;
}

// get the default speed and turn rate at this time
speed = powerProfile[timeInSeconds];
turn = 0;

// different cases for different line tracking sensor readings
switch (binaryValue) {
case 1: // on line edge
turn = 0;
break;
case 7: // all sensors on (maybe at cross)
if (time > stopTime) {
atCross = true;
speed = 0;
}
break;
case 0: // all sensors off
if (previousValue == 0 || previousValue == 1) {
turn = steeringGain;
} else {
turn = -steeringGain;
}
break;
default: // all other cases
turn = -steeringGain;
}
// print current status for debugging
if (binaryValue != previousValue) {
System.out.println("Time: " + time + " Sensor: " + binaryValue + " speed: " + speed + " turn: " + turn + " atCross: " + atCross);
}

// set the robot speed and direction
drive.arcadeDrive(speed, turn);

if (binaryValue != 0) {
previousValue = binaryValue;
}
oldTimeInSeconds = timeInSeconds;

Timer.delay(0.01);
}
// Done with loop - stop the robot. Robot ought to be at the end of the line
drive.arcadeDrive(0, 0);
}

/**
* This function is called once each time the robot enters operator control.
*/
public void operatorControl() {
// supply your own teleop code here
}
}

All i got rid of was the comments and the section of code that reverses the motors because it screwed with the wheel rotation.
I have wired it correctly according to the code is there something I'm missing

warfaj
07-02-2011, 07:24
Try getting rid of the time and steering gain. Then add some additional cases so that you know exactly what happens when each of the light sensors are triggered.

Twisted eric
07-02-2011, 13:59
thanks i will try that today after school