lejos.navigation
Class TachoNavigator

java.lang.Object
  lejos.navigation.TachoNavigator

All Implemented Interfaces:

Navigator

Direct Known Subclasses:

CompassNavigator

public class TachoNavigator
extends Object
implements Navigator

The TachoNavigator class can keep track of the robot position and the direction angle it faces; It uses a _pilot object to control NXT robot movements.
The position and direction angle values are updated automatically when the movement command returns after the movement is complete and and after stop() command is issued. However, some commands optionally return immediately, to permit sensor monitoring in the main thread. It is then the programmers responsibility to call updatePosition() when the robot motion is completed. All angles are in degrees, distances in the units used to specify robot dimensions. As with pilot, the robot must be have two independently controlled drive wheels. The assumed initial position of the robot is at (0,0) and initial angle 0 i.e. pointing in the +X direction.

Field Summary

protected float	_heading
protected int	_left0
protected Pilot	_pilot
protected int	_right0

Constructor Summary

TachoNavigator(float wheelDiameter, float driveLength)
Overloaded TachoNavigator constructor that assumes the following:
Left motor = Motor.A Right motor = Motor.C

TachoNavigator(float wheelDiameter, float trackWidth, Motor leftMotor, Motor rightMotor)

TachoNavigator(float wheelDiameter, float trackWidth, Motor leftMotor, Motor rightMotor, boolean reverse)
Allocates a Navigator object and initializes it with the proper motors.

TachoNavigator(Pilot pilot)

Method Summary

float	angleTo(float x, float y) returns the direction angle (degrees) to point with coordinates (x,y)
void	backward() Moves the NXT robot backward until stop() is called.
float	distanceTo(float x, float y) distance from robot to the point with coordinates (x,y) .
void	forward() Moves the NXT robot forward until stop() is called.
float	getAngle() Returns the current angle the NXT robot is facing, relative to the +X axis direction; the +Y direction is 90 degrees.
Pilot	getPilot()
float	getX() Returns the current x coordinate of the NXT.
float	getY() Returns the current y coordinate of the NXT.
void	goTo(float x, float y) Rotates the NXT robot towards the target point (x,y) and moves the required distance.
void	goTo(float x, float y, boolean immediateReturn) Rotates the NXT robot towards the target point (x,y) and moves the required distance.
boolean	isMoving() returns true iff the robot is moving under power
void	rotate(float angle) Rotates the NXT robot a specific number of degrees in a direction (+ or -).
void	rotate(float angle, boolean immediateReturn) Rotates the NXT robot a specific number of degrees in a direction (+ or -).
void	rotateLeft() Rotates the NXT to the left (increasing angle) until stop() is called;
void	rotateRight() Rotates the NXT to the right (decreasing angle) until stop() is called;
void	rotateTo(float angle) Rotates the NXT robot to point in a specific direction.
void	rotateTo(float angle, boolean immediateReturn) Rotates the NXT robot to point in a specific direction.
void	setPosition(float x, float y, float directionAngle) sets robot location (x,y) and direction angle
void	setSpeed(int speed) sets the motor speed of the robot, in degrees/second.
void	stop() Halts the NXT robot and calculates new x, y coordinates.
void	travel(float distance) Moves the NXT robot a specific distance.
void	travel(float distance, boolean immediateReturn) Moves the NXT robot a specific distance.
void	turn(float radius) Moves the NXT robot in a circular path with a specified radius.
void	turn(float radius, int angle) Moves the NXT robot in a circular path through a specific angle; If waitForCompletion is true, returns when angle is reached.
void	turn(float radius, int angle, boolean immediateReturn) Moves the NXT robot in a circular path through a specific angle; If waitForCompletion is true, returns when angle is reached.
void	updatePosition() Updates robot location (x,y) and direction angle.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait

Field Detail

_heading

protected float _heading

_left0

protected int _left0

_right0

protected int _right0

_pilot

protected Pilot _pilot

Constructor Detail

TachoNavigator

public TachoNavigator(float wheelDiameter,
                      float trackWidth,
                      Motor leftMotor,
                      Motor rightMotor,
                      boolean reverse)

Allocates a Navigator object and initializes it with the proper motors. The x and y values and the direction angle are all initialized to 0, so if the first move is forward() the robot will run along the x axis.

Parameters:

wheelDiameter - The diameter of the wheel, usually printed right on the wheel, in centimeters (e.g. 49.6 mm = 4.96 cm = 1.95 in)

trackWidth - The distance from the center of the left tire to the center of the right tire, in units of your choice

rightMotor - The motor used to drive the right wheel e.g. Motor.C.

leftMotor - The motor used to drive the left wheel e.g. Motor.A.

reverse - If motor.forward() dives the robot backwars, set this parameter true.

TachoNavigator

public TachoNavigator(float wheelDiameter,
                      float trackWidth,
                      Motor leftMotor,
                      Motor rightMotor)

TachoNavigator

public TachoNavigator(Pilot pilot)

TachoNavigator

public TachoNavigator(float wheelDiameter,
                      float driveLength)

Overloaded TachoNavigator constructor that assumes the following:
Left motor = Motor.A Right motor = Motor.C

Parameters:

wheelDiameter - The diameter of the wheel, usually printed right on the wheel, in centimeters (e.g. 49.6 mm = 4.96 cm)

driveLength - The distance from the center of the left tire to the center of the right tire,

Method Detail

getPilot

public Pilot getPilot()

getX

public float getX()

Returns the current x coordinate of the NXT.

Specified by:

getX in interface Navigator

Returns:

float Present x coordinate.

getY

public float getY()

Returns the current y coordinate of the NXT. Note: At present it will only give an updated reading when the NXT is stopped.

Specified by:

getY in interface Navigator

Returns:

float Present y coordinate.

getAngle

public float getAngle()

Returns the current angle the NXT robot is facing, relative to the +X axis direction; the +Y direction is 90 degrees. Note: At present it will only give an updated reading when the NXT is stopped.

Specified by:

getAngle in interface Navigator

Returns:

float Angle in degrees.

setPosition

public void setPosition(float x,
                        float y,
                        float directionAngle)

sets robot location (x,y) and direction angle

Specified by:

setPosition in interface Navigator

Parameters:

x - the x coordinate of the robot

y - the y coordinate of the robot

directionAngle - the angle the robot is heading, measured from the x axis. 90 degrees is the +Y direction

setSpeed

public void setSpeed(int speed)

sets the motor speed of the robot, in degrees/second.

Specified by:

setSpeed in interface Navigator

forward

public void forward()

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

Specified by:

forward in interface Navigator

See Also:

Navigator.stop().

backward

public void backward()

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

Specified by:

backward in interface Navigator

See Also:

Navigator.stop().

stop

public void stop()

Halts the NXT robot and calculates new x, y coordinates.

Specified by:

stop in interface Navigator

See Also:

Navigator.forward().

isMoving

public boolean isMoving()

returns true iff the robot is moving under power

Specified by:

isMoving in interface Navigator

travel

public void travel(float distance)

Moves the NXT robot a specific distance. A positive value moves it forwards and a negative value moves it backwards. The robot position is updated atomatically when the method returns.

Specified by:

travel in interface Navigator

Parameters:

distance - The positive or negative distance to move the robot, same units as _wheelDiameter

travel

public void travel(float distance,
                   boolean immediateReturn)

Moves the NXT robot a specific distance. A positive value moves it forwards and a negative value moves it backwards. If immediateReturnis true, method returns immidiately and your code MUST call updatePostion() when the robot has stopped. Otherwise, the robot position is lost.

Specified by:

travel in interface Navigator

Parameters:

distance - The positive or negative distance to move the robot, same units as _wheelDiameter

immediateReturn - iff true, the method returns immediately, in which case the programmer
is responsible for calling updatePosition() before the robot moves again.

rotateLeft

public void rotateLeft()

Rotates the NXT to the left (increasing angle) until stop() is called;

Specified by:

rotateLeft in interface Navigator

rotateRight

public void rotateRight()

Rotates the NXT to the right (decreasing angle) until stop() is called;

Specified by:

rotateRight in interface Navigator

rotate

public void rotate(float angle)

Rotates the NXT robot a specific number of degrees in a direction (+ or -).

Specified by:

rotate in interface Navigator

Parameters:

angle - Angle to rotate in degrees. A positive value rotates left, a negative value right.

rotate

public void rotate(float angle,
                   boolean immediateReturn)

Rotates the NXT robot a specific number of degrees in a direction (+ or -). If immediateReturn is true, method returns immidiately and your code MUST call updatePostion() when the robot has stopped. Otherwise, the robot position is lost.

Specified by:

rotate in interface Navigator

Parameters:

angle - Angle to rotate in degrees. A positive value rotates left, a negative value right.

immediateReturn - iff true, the method returns immediately, in which case the programmer
is responsible for calling updatePosition() before the robot moves again.

rotateTo

public void rotateTo(float angle)

Rotates the NXT robot to point in a specific direction. It will take the shortest path necessary to point to the desired angle.

Specified by:

rotateTo in interface Navigator

Parameters:

angle - The angle to rotate to, in degrees.

rotateTo

public void rotateTo(float angle,
                     boolean immediateReturn)

Rotates the NXT robot to point in a specific direction. It will take the shortest path necessary to point to the desired angle. If immediateReturnis true, method returns immidiately and your code MUST call updatePostion() when the robot has stopped. Otherwise, the robot position is lost.

Specified by:

rotateTo in interface Navigator

Parameters:

angle - The angle to rotate to, in degrees.

immediateReturn - iff true, method returns immediately and the programmer is responsible for calling updatePosition() before the robot moves again.

goTo

public void goTo(float x,
                 float y)

Rotates the NXT robot towards the target point (x,y) and moves the required distance. Method returns when target point is reached, and the robot position is updated;

Specified by:

goTo in interface Navigator

Parameters:

x - The x coordinate to move to.

y - The y coordinate to move to.

goTo

public void goTo(float x,
                 float y,
                 boolean immediateReturn)

Rotates the NXT robot towards the target point (x,y) and moves the required distance. Method returns when target point is reached, and the robot position is updated;

Specified by:

goTo in interface Navigator

Parameters:

x - The x coordinate to move to.

y - The y coordinate to move to.

immediateReturn - iff true, method returns immediately

distanceTo

public float distanceTo(float x,
                        float y)

distance from robot to the point with coordinates (x,y) .

Specified by:

distanceTo in interface Navigator

Parameters:

x - coordinate of the point

y - coordinate of the point

Returns:

the distance from the robot current location to the point

angleTo

public float angleTo(float x,
                     float y)

returns the direction angle (degrees) to point with coordinates (x,y)

Specified by:

angleTo in interface Navigator

Parameters:

x - coordinate of the point

y - coordinate of the point

Returns:

the direction angle to the point (x,y) from the NXT. Rotate to this angle to head toward it.

updatePosition

public void updatePosition()

Updates robot location (x,y) and direction angle. Called by stop, and movement commands that terminate when complete. If you use a movement command that returns immediately, you MUST call this method when the movement is complete. It may also be called while movement is on progress.

Specified by:

updatePosition in interface Navigator

turn

public void turn(float radius)

Moves the NXT robot in a circular path with a specified radius.
The center of the turning circle is on the right side of the robot iff parameter radius is negative;
Postcondition: motor speed is NOT restored to previous value;

Parameters:

radius - is the radius of the circular path. If positive, the left wheel is on the inside of the turn. If negative, the left wheel is on the outside.

turn

public void turn(float radius,
                 int angle)

Moves the NXT robot in a circular path through a specific angle; If waitForCompletion is true, returns when angle is reached.
The center of the turning circle is on the right side of the robot iff parameter radius is negative. Robot will stop when total rotation equals angle. If angle is negative, robot will move travel backwards.

Parameters:

radius - radius of the turning circle

angle - the angle by which the robot heading changes, + or -

turn

public void turn(float radius,
                 int angle,
                 boolean immediateReturn)

Moves the NXT robot in a circular path through a specific angle; If waitForCompletion is true, returns when angle is reached.
The center of the turning circle is on the right side of the robot iff parameter radius is negative. Robot will stop when total rotation equals angle. If angle is negative, robot will travel backwards.

Parameters:

radius - see turn(turnRage, angle)

immediateReturn - iff true, the method returns immediately, in which case the programmer
is responsible for calling updatePosition() before the robot moves again.