icommand.navigation
Class Pilot

java.lang.Object
  extended by icommand.navigation.Pilot
Direct Known Subclasses:
CompassPilot

public class Pilot
extends java.lang.Object

The Pilot class is a software abstraction of the Pilot mechanism of a NXT robot. It contains methods to control robot movents: travel forward or backward in a straight line or a circular path or rotate to a new direction.
Note: this class will only work with two independently controlled Pilot motors to steer differentially, so it can rotate within its own footprint (i.e. turn on one spot).
It can be used with robots that have reversed motor design: the robot moves in the direction opposite to the the dirction of motor rotation. Uses the Motor class, which regulates motor speed using the NXT motor's built in tachometer.
Some methods optionally return immediately so the thread that called the method can monitor sensors and call stop() if necessary.
Uses the smoothAcceleration property of Motors to improve motor symchronication Example:

        Pilot sc = new Pilot(2.1f,4.4f,Motor.A, Motor.C,true);
        sc.setSpeed(720);// 2 RPM
        sc.travel(12);
        sc.rotate(-90);
        sc.travel(-12,true);
        while(sc.isMoving())Thread.yield();
        sc.rotate(-90);
        sc.rotateTo(270);
        sc.steer(-50,180,true);
        while(sc.isMoving())Thread.yield();
        sc.steer(100);
        try{Thread.sleep(1000);}
   catch(InterruptedException e){}
        sc.stop();
 


Field Summary
 double _degPerDistance
          motor degrees per unit of travel
 Motor _left
          left motor
 Motor _right
          right motor
protected  int _speed
          motor speed degrees per second.
 double _trackWidth
          distance between wheels - used in steer()
 double _wheelDiameter
          diameter of tires
 
Constructor Summary
Pilot(double wheelDiameter, double trackWidth, Motor leftMotor, Motor rightMotor)
          Allocates a Pilot object, and sets the physical parameters of the NXT robot.
Pilot(double wheelDiameter, double trackWidth, Motor leftMotor, Motor rightMotor, boolean reverse)
          Allocates a Pilot object, and sets the physical parameters of the NXT robot.
 
Method Summary
 void backward()
          Moves the NXT robot backward until stop() is called.
 void forward()
          Moves the NXT robot forward until stop() is called.
 int getAngle()
          returns the angle of rotation of the robot since last call to reset of tacho count;
 int getLeftCount()
          returns tachoCount of left motor; Positive value means motor has moved the robot forward;
 int getRightCount()
          returns tachoCount of the right motor; Positive value means motor has moved the robot forward;
 int getSpeed()
          Returns speed of both motors, degrees/sec
 double getTravelDistance()
          returns distance taveled since last reset of tacho count
 double getTurnRatio()
          return ratatio of Motor revolutions per 360 degree rotation of the robot
 boolean isMoving()
          returns true iff the NXT robot is moving
 void resetTachoCount()
          resets tacho count for both motors
 void rotate(int angle)
          Rotates the NXT robot through a specific angle; Rotates left if angle is positive, right if negative, Returns when angle is reached.
 void rotate(int angle, boolean immediateReturn)
          Rotates the NXT robot through a specific angle; Rotates left if angle is positive, right if negative; Returns immediately iff immediateReturn is true.
 void setSpeed(int speed)
          Sets speed of both motors, degrees/sec; also sets retulate speed true
 void steer(int turnRate)
          Moves the NXT robot in a circular path at a specific turn rate.
 void steer(int turnRate, int angle)
          Moves the NXT robot in a circular path through a specific angle;
Negative turnRate means center of turning circle is on right side of the robot;
Range of turnRate values : -200 : 200 ; Robot will stop when total rotation equals angle.
 void steer(int turnRate, int angle, boolean immediateReturn)
          Moves the NXT robot in a circular path, and stops when the direction it is facing has changed by a specific angle;
Returns immediately if immediateReturn is true.
 void stop()
          Stops the NXT robot
 void travel(double distance)
          Moves the NXT robot a specific distance;
A positive distance causes forward motion; negative distance moves backward.
 void travel(double distance, boolean immediateReturn)
          Moves the NXT robot a specific distance; if immediateReturn is true, method returns immediately.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

_left

public Motor _left
left motor


_right

public Motor _right
right motor


_degPerDistance

public final double _degPerDistance
motor degrees per unit of travel


_speed

protected int _speed
motor speed degrees per second. Used by all methods that cause movememt


_trackWidth

public final double _trackWidth
distance between wheels - used in steer()


_wheelDiameter

public final double _wheelDiameter
diameter of tires

Constructor Detail

Pilot

public Pilot(double wheelDiameter,
             double trackWidth,
             Motor leftMotor,
             Motor rightMotor)
Allocates a Pilot object, and sets the physical parameters of the NXT robot.
Assumes Motor.forward() causes the robot to move forward);

Parameters:
wheelDiameter - Diameter of the tire, in any convenient units. (The diameter in mm is usually printed on the tire).
trackWidth - Distance between center of right tire and center of left tire, in same units as wheelDiameter

Pilot

public Pilot(double wheelDiameter,
             double trackWidth,
             Motor leftMotor,
             Motor rightMotor,
             boolean reverse)
Allocates a Pilot object, and sets the physical parameters of the NXT robot.

Parameters:
wheelDiameter - Diameter of the tire, in any convenient units. (The diameter in mm is usually printed on the tire).
trackWidth - Distance between center of right tire and center of left tire, in the same units as wheelDiameter
reverse - if true, the NXT robot moves forward when the motors are running backward.
Method Detail

getLeftCount

public int getLeftCount()
returns tachoCount of left motor; Positive value means motor has moved the robot forward;


getRightCount

public int getRightCount()
returns tachoCount of the right motor; Positive value means motor has moved the robot forward;


getTurnRatio

public double getTurnRatio()
return ratatio of Motor revolutions per 360 degree rotation of the robot


setSpeed

public void setSpeed(int speed)
Sets speed of both motors, degrees/sec; also sets retulate speed true


getSpeed

public int getSpeed()
Returns speed of both motors, degrees/sec


forward

public void forward()
Moves the NXT robot forward until stop() is called.


backward

public void backward()
Moves the NXT robot backward until stop() is called.


rotate

public void rotate(int angle)
Rotates the NXT robot through a specific angle; Rotates left if angle is positive, right if negative, Returns when angle is reached. Wheels turn in opposite directions producing a zero radius turn.

Parameters:
angle - degrees. Positive angle rotates to the left (clockwise); negative to the right.
Requires correct values for wheel diameter and track width.

rotate

public void rotate(int angle,
                   boolean immediateReturn)
Rotates the NXT robot through a specific angle; Rotates left if angle is positive, right if negative; Returns immediately iff immediateReturn is true. Wheels turn in opposite directions producing a zero radius turn.

Parameters:
angle - degrees. Positive angle rotates to the left; negative to the right.
Requires correct values for wheel diameter and track width.
immediateReturn - if true this method returns immediately

getAngle

public int getAngle()
returns the angle of rotation of the robot since last call to reset of tacho count;


stop

public void stop()
Stops the NXT robot


isMoving

public boolean isMoving()
returns true iff the NXT robot is moving


resetTachoCount

public void resetTachoCount()
resets tacho count for both motors


getTravelDistance

public double getTravelDistance()
returns distance taveled since last reset of tacho count


travel

public void travel(double distance)
Moves the NXT robot a specific distance;
A positive distance causes forward motion; negative distance moves backward.

Parameters:
distance - of robot movement. Unit of measure for distance must be same as wheelDiameter and trackWidth

travel

public void travel(double distance,
                   boolean immediateReturn)
Moves the NXT robot a specific distance; if immediateReturn is true, method returns immediately.
A positive distance causes forward motion; negative distance moves backward.

Parameters:
immediateReturn - If true, method returns immediately, and robot stops after traveling the distance. If false, method returns immediately.

steer

public void steer(int turnRate)
Moves the NXT robot in a circular path at a specific turn rate.
The center of the turning circle is on the right side of the robot iff parameter turnRate is negative;
turnRate values are between -200 and +200;

Parameters:
turnRate - If positive, the left wheel is on the inside of the turn. If negative, the left wheel is on the outside. This parameter determines the ratio of inner wheel speed to outer wheel speed (as a percent).
Formula: ratio = 100 - abs(turnRate). When the ratio is negative, the outer and inner wheels rotate in opposite directions.
Examples:
  • steer(25)-> inner wheel turns at 75% of the speed of the outer wheel
  • steer(100) -> inner wheel stops.
  • steer(200) -> means that the inner wheel turns at the same speed as the outer wheel - a zero radius turn.

steer

public void steer(int turnRate,
                  int angle)
Moves the NXT robot in a circular path through a specific angle;
Negative turnRate means center of turning circle is on right side of the robot;
Range of turnRate values : -200 : 200 ; Robot will stop when total rotation equals angle. If angle is negative, robot will move travel backwards.

Parameters:
turnRate - If positive, the left wheel is on the inside of the turn. If negative, the left wheel is on the outside. This parameter determines the ratio of inner wheel speed to outer wheel speed (as a percent).
angle - the angle through which the robot will rotate and then stop. If negative, robot traces the turning circle backwards.

steer

public void steer(int turnRate,
                  int angle,
                  boolean immediateReturn)
Moves the NXT robot in a circular path, and stops when the direction it is facing has changed by a specific angle;
Returns immediately if immediateReturn is true. The robot will stop automatically when the turm is complete. The center of the turning circle is on right side of the robot iff parameter turnRate is negative
turnRate values are between -200 and +200;

Parameters:
turnRate - If positive, the left wheel is on the inside of the turn. If negative, the left wheel is on the outside. This parameter determines the ratio of inner wheel speed to outer wheel speed (as a percent).
angle - the angle through which the robot will rotate and then stop. If negative, robot traces the turning circle backwards.
immediateReturn - iff true, method returns immedediately.


Copyright 2006. All Rights Reserved.