package lejos.robotics.navigation;
import lejos.nxt.Battery;
import lejos.robotics.TachoMotor;
/*
* WARNING: THIS CLASS IS SHARED BETWEEN THE classes AND pccomms PROJECTS.
* DO NOT EDIT THE VERSION IN pccomms AS IT WILL BE OVERWRITTEN WHEN THE PROJECT IS BUILT.
*/
/**
* The TachoPilot class is a software abstraction of the Pilot mechanism of a
* NXT robot. It contains methods to control robot movements: travel forward or
* backward in a straight line or a circular path or rotate to a new direction.<br>
* Note: this class will only work with two independently controlled motors to
* steer differentially, so it can rotate within its own footprint (i.e. turn on
* one spot).<br>
* It can be used with robots that have reversed motor design: the robot moves
* in the direction opposite to the the direction of motor rotation. Uses the
* Motor class, which regulates motor speed using the NXT motor's built in
* tachometer.<br>
* Some methods optionally return immediately so the thread that called the
* method can monitor sensors and call stop() if necessary.<br>
* Uses the smoothAcceleration property of Motors to improve motor
* synchronization when starting a movement. Example:
* <p>
* <code><pre>
* Pilot pilot = new TachoPilot(2.1f, 4.4f, Motor.A, Motor.C, true); // parameters in inches
* pilot.setRobotSpeed(10); // inches per second
* pilot.travel(12); // inches
* pilot.rotate(-90); // degree clockwise
* pilot.travel(-12,true);
* while(pilot.isMoving())Thread.yield();
* pilot.rotate(-90);
* pilot.rotateTo(270);
* pilot.steer(-50,180,true);
* while(pilot.isMoving())Thread.yield();
* pilot.steer(100);
* try{Thread.sleep(1000);}
* catch(InterruptedException e){}
* pilot.stop();
* </pre></code>
* </p>
*
* Note: if you are sure you do not want to use any other part of navigation you
* can as well use "TachoPilot pilot = new TachoPilot(...)" instead of
* "Pilot pilot = new TachoPilot(...)"
**/
public class TachoPilot implements Pilot {
/**
* Left motor.
*/
protected final TachoMotor _left;
/**
* Right motor.
*/
protected final TachoMotor _right;
/**
* Left motor degrees per unit of travel.
*/
protected final float _leftDegPerDistance;
/**
* Right motor degrees per unit of travel.
*/
protected final float _rightDegPerDistance;
/**
* Left motor revolutions for 360 degree rotation of robot (motors running
* in opposite directions). Calculated from wheel diameter and track width.
* Used by rotate() and steer() methods.
**/
protected final float _leftTurnRatio;
/**
* Right motor revolutions for 360 degree rotation of robot (motors running
* in opposite directions). Calculated from wheel diameter and track width.
* Used by rotate() and steer() methods.
**/
protected final float _rightTurnRatio;
/**
* Speed of robot for moving in wheel diameter units per seconds. Set by
* setSpeed(), setMoveSpeed()
*/
protected float _robotMoveSpeed;
/**
* Speed of robot for turning in degree per seconds.
*/
protected float _robotTurnSpeed;
/**
* Motor speed degrees per second. Used by forward(),backward() and steer().
*/
protected int _motorSpeed;
/**
* Motor rotation forward makes robot move forward if parity == 1.
*/
private byte _parity;
/**
* If true, motor speed regulation is turned on. Default = true.
*/
private boolean _regulating = true;
/**
* Distance between wheels. Used in steer() and rotate().
*/
protected final float _trackWidth;
/**
* Diameter of left wheel.
*/
protected final float _leftWheelDiameter;
/**
* Diameter of right wheel.
*/
protected final float _rightWheelDiameter;
/**
* Allocates a TachoPilot object, and sets the physical parameters of the
* NXT robot.<br>
* Assumes Motor.forward() causes the robot to move forward.
*
* @param wheelDiameter
* Diameter of the tire, in any convenient units (diameter in mm
* is usually printed on the tire).
* @param trackWidth
* Distance between center of right tire and center of left tire,
* in same units as wheelDiameter.
* @param leftMotor
* The left Motor (e.g., Motor.C).
* @param rightMotor
* The right Motor (e.g., Motor.A).
*/
public TachoPilot(final float wheelDiameter, final float trackWidth,
final TachoMotor leftMotor, final TachoMotor rightMotor) {
this(wheelDiameter, trackWidth, leftMotor, rightMotor, false);
}
/**
* Allocates a TachoPilot object, and sets the physical parameters of the
* NXT robot.<br>
*
* @param wheelDiameter
* Diameter of the tire, in any convenient units (diameter in mm
* is usually printed on the tire).
* @param trackWidth
* Distance between center of right tire and center of left tire,
* in same units as wheelDiameter.
* @param leftMotor
* The left Motor (e.g., Motor.C).
* @param rightMotor
* The right Motor (e.g., Motor.A).
* @param reverse
* If true, the NXT robot moves forward when the motors are
* running backward.
*/
public TachoPilot(final float wheelDiameter, final float trackWidth,
final TachoMotor leftMotor, final TachoMotor rightMotor,
final boolean reverse) {
this(wheelDiameter, wheelDiameter, trackWidth, leftMotor, rightMotor,
reverse);
}
/**
* Allocates a TachoPilot object, and sets the physical parameters of the
* NXT robot.<br>
*
* @param leftWheelDiameter
* Diameter of the left wheel, in any convenient units (diameter
* in mm is usually printed on the tire).
* @param rightWheelDiameter
* Diameter of the right wheel. You can actually fit
* intentionally wheels with different size to your robot. If you
* fitted wheels with the same size, but your robot is not going
* straight, try swapping the wheels and see if it deviates into
* the other direction. That would indicate a small difference in
* wheel size. Adjust wheel size accordingly. The minimum change
* in wheel size which will actually have an effect is given by
* minChange = A*wheelDiameter*wheelDiameter/(1-(A*wheelDiameter)
* where A = PI/(moveSpeed*360). Thus for a moveSpeed of 25
* cm/second and a wheelDiameter of 5,5 cm the minChange is about
* 0,01058 cm. The reason for this is, that different while sizes
* will result in different motor speed. And that is given as an
* integer in degree per second.
* @param trackWidth
* Distance between center of right tire and center of left tire,
* in same units as wheelDiameter.
* @param leftMotor
* The left Motor (e.g., Motor.C).
* @param rightMotor
* The right Motor (e.g., Motor.A).
* @param reverse
* If true, the NXT robot moves forward when the motors are
* running backward.
*/
public TachoPilot(final float leftWheelDiameter,
final float rightWheelDiameter, final float trackWidth,
final TachoMotor leftMotor, final TachoMotor rightMotor,
final boolean reverse) {
// left
_left = leftMotor;
_leftWheelDiameter = leftWheelDiameter;
_leftTurnRatio = trackWidth / leftWheelDiameter;
_leftDegPerDistance = 360 / ((float) Math.PI * leftWheelDiameter);
// right
_right = rightMotor;
_rightWheelDiameter = rightWheelDiameter;
_rightTurnRatio = trackWidth / rightWheelDiameter;
_rightDegPerDistance = 360 / ((float) Math.PI * rightWheelDiameter);
// both
_trackWidth = trackWidth;
_parity = (byte) (reverse ? -1 : 1);
setSpeed(360);
}
/**
* @return left motor.
*/
public TachoMotor getLeft() {
return _left;
}
/**
* @return right motor.
*/
public TachoMotor getRight() {
return _right;
}
/**
* @return tachoCount of left motor. Positive value means motor has moved
* the robot forward.
*/
public int getLeftCount() {
return _parity * _left.getTachoCount();
}
/**
* @return tachoCount of the right motor. Positive value means motor has
* moved the robot forward.
*/
public int getRightCount() {
return _parity * _right.getTachoCount();
}
/**
* @return actual speed of left motor in degrees per second. A negative
* value if motor is rotating backwards. Updated every 100 ms.
**/
public int getLeftActualSpeed() {
return _left.getRotationSpeed();
}
/**
* @return actual speed of right motor in degrees per second. A negative
* value if motor is rotating backwards. Updated every 100 ms.
**/
public int getRightActualSpeed() {
return _right.getRotationSpeed();
}
/**
* @return ratio of motor revolutions per 360 degree rotation of the robot.
* If your robot has wheels with different size, it is the average.
*/
public float getTurnRatio() {
return (_leftTurnRatio + _rightTurnRatio) / 2.0f;
}
/**
* Sets speed of both motors, as well as moveSpeed and turnSpeed. Only use
* if your wheels have the same size.
*
* @param speed
* The wanted speed in degrees per second.
*/
public void setSpeed(final int speed) {
_motorSpeed = speed;
_robotMoveSpeed = speed
/ Math.max(_leftDegPerDistance, _rightDegPerDistance);
_robotTurnSpeed = speed / Math.max(_leftTurnRatio, _rightTurnRatio);
setSpeed(speed, speed);
}
private void setSpeed(final int leftSpeed, final int rightSpeed) {
_left.regulateSpeed(_regulating);
_left.smoothAcceleration(!isMoving());
_right.regulateSpeed(_regulating);
_right.smoothAcceleration(!isMoving());
_left.setSpeed(leftSpeed);
_right.setSpeed(rightSpeed);
}
/**
* also sets _motorSpeed
*
* @see lejos.robotics.navigation.Pilot#setMoveSpeed(float)
*/
public void setMoveSpeed(float speed) {
_robotMoveSpeed = speed;
_motorSpeed = Math.round(0.5f * speed
* (_leftDegPerDistance + _rightDegPerDistance));
setSpeed(Math.round(speed * _leftDegPerDistance), Math.round(speed
* _rightDegPerDistance));
}
/**
* @see lejos.robotics.navigation.Pilot#getMoveSpeed()
*/
public float getMoveSpeed() {
return _robotMoveSpeed;
}
/**
* @see lejos.robotics.navigation.Pilot#getMoveMaxSpeed()
*/
public float getMoveMaxSpeed() {
// it is generally assumed, that the maximum accurate speed of Motor is
// 100 degree/second * Voltage
return Battery.getVoltage() * 100.0f
/ Math.max(_leftDegPerDistance, _rightDegPerDistance);
// max degree/second divided by degree/unit = unit/second
}
/**
* @see lejos.robotics.navigation.Pilot#setTurnSpeed(float)
*/
public void setTurnSpeed(float speed) {
_robotTurnSpeed = speed;
setSpeed(Math.round(speed * _leftTurnRatio), Math.round(speed
* _rightTurnRatio));
}
/**
* @see lejos.robotics.navigation.Pilot#getTurnSpeed()
*/
public float getTurnSpeed() {
return _robotTurnSpeed;
}
/**
* @see lejos.robotics.navigation.Pilot#getTurnMaxSpeed()
*/
public float getTurnMaxSpeed() {
// it is generally assumed, that the maximum accurate speed of Motor is
// 100 degree/second * Voltage
return Battery.getVoltage() * 100.0f
/ Math.max(_leftTurnRatio, _rightTurnRatio);
// max degree/second divided by degree/unit = unit/second
}
/**
* Moves the NXT robot forward until stop() is called.
*/
public void forward() {
setSpeed(Math.round(_robotMoveSpeed * _leftDegPerDistance), Math
.round(_robotMoveSpeed * _rightDegPerDistance));
if (_parity == 1) {
fwd();
} else {
bak();
}
}
/**
* Moves the NXT robot backward until stop() is called.
*/
public void backward() {
setSpeed(Math.round(_robotMoveSpeed * _leftDegPerDistance), Math
.round(_robotMoveSpeed * _rightDegPerDistance));
if (_parity == 1) {
bak();
} else {
fwd();
}
}
/**
* Rotates the NXT robot through a specific angle. Returns when angle is
* reached. Wheels turn in opposite directions producing a zero radius turn.<br>
* Note: Requires correct values for wheel diameter and track width.
*
* @param angle
* The wanted angle of rotation in degrees. Positive angle rotate
* left (clockwise), negative right.
*/
public void rotate(final float angle) {
rotate(angle, false);
}
/**
* Rotates the NXT robot through a specific angle. Returns when angle is
* reached. Wheels turn in opposite directions producing a zero radius turn.<br>
* Note: Requires correct values for wheel diameter and track width.
*
* @param angle
* The wanted angle of rotation in degrees. Positive angle rotate
* left (clockwise), negative right.
* @param immediateReturn
* If true this method returns immediately.
*/
public void rotate(final float angle, final boolean immediateReturn) {
setSpeed(Math.round(_robotTurnSpeed * _leftTurnRatio), Math
.round(_robotTurnSpeed * _rightTurnRatio));
int rotateAngleLeft = _parity * (int) (angle * _leftTurnRatio);
int rotateAngleRight = _parity * (int) (angle * _rightTurnRatio);
_left.rotate(-rotateAngleLeft, true);
_right.rotate(rotateAngleRight, immediateReturn);
if (!immediateReturn) {
while (_left.isMoving() || _right.isMoving())
// changed isRotating() to isMoving() as this covers what we
// need and alows us to keep the interface small
Thread.yield();
}
}
/**
* @return the angle of rotation of the robot since last call to reset of
* tacho count;
*/
public float getAngle() {
return _parity
* ((_right.getTachoCount() / _rightTurnRatio) - (_left
.getTachoCount() / _leftTurnRatio)) / 2.0f;
}
/**
* Stops the NXT robot.
*/
public void stop() {
_left.stop();
_right.stop();
}
/**
* @return true if the NXT robot is moving.
**/
public boolean isMoving() {
return _left.isMoving() || _right.isMoving();
}
/**
* Resets tacho count for both motors.
**/
public void reset() {
_left.resetTachoCount();
_right.resetTachoCount();
}
/**
* @return distance traveled since last reset of tacho count.
**/
public float getTravelDistance() {
float left = _left.getTachoCount() / _leftDegPerDistance;
float right = _right.getTachoCount() / _rightDegPerDistance;
return _parity * (left + right) / 2.0f;
}
/**
* Moves the NXT robot a specific distance in an (hopefully) straight line.<br>
* A positive distance causes forward motion, a negative distance moves
* backward. If a drift correction has been specified in the constructor it
* will be applied to the left motor.
*
* @param distance
* The distance to move. Unit of measure for distance must be
* same as wheelDiameter and trackWidth.
**/
public void travel(final float distance) {
travel(distance, false);
}
/**
* Moves the NXT robot a specific distance in an (hopefully) straight line.<br>
* A positive distance causes forward motion, a negative distance moves
* backward. If a drift correction has been specified in the constructor it
* will be applied to the left motor.
*
* @param distance
* The distance to move. Unit of measure for distance must be
* same as wheelDiameter and trackWidth.
* @param immediateReturn
* If true this method returns immediately.
*/
public void travel(final float distance, final boolean immediateReturn) {
setSpeed(Math.round(_robotMoveSpeed * _leftDegPerDistance), Math
.round(_robotMoveSpeed * _rightDegPerDistance));
_left.rotate((int) (_parity * distance * _leftDegPerDistance), true);
_right.rotate((int) (_parity * distance * _rightDegPerDistance),
immediateReturn);
if (!immediateReturn) {
while (_left.isMoving() || _right.isMoving())
// changed isRotating() to isMoving() as this covers what we
// need and alows us to keep the interface small
Thread.yield();
}
}
public void steer(final float turnRate) {
steer(turnRate, Float.POSITIVE_INFINITY, true);
}
public void steer(final float turnRate,float angle) {
steer(turnRate, angle, false);
}
public void steer(final float turnRate, final float angle,
final boolean immediateReturn) {
// TODO: make this work with wheels of different size
TachoMotor inside;
TachoMotor outside;
float rate = turnRate;
if (rate < -200) {
rate = -200;
}
if (rate > 200) {
rate = 200;
}
if (rate == 0) {
if (angle < 0) {
backward();
} else {
forward();
}
return;
}
if (turnRate < 0) {
inside = _right;
outside = _left;
rate = -rate;
} else {
inside = _left;
outside = _right;
}
outside.setSpeed(_motorSpeed);
float steerRatio = 1 - rate / 100.0f;
inside.setSpeed((int) (_motorSpeed * steerRatio));
if (angle == Integer.MAX_VALUE) // no limit angle for turn
{
if (_parity == 1) {
outside.forward();
} else {
outside.backward();
}
if (_parity * steerRatio > 0) {
inside.forward();
} else {
inside.backward();
}
return;
}
float rotAngle = angle * _trackWidth * 2
/ (_leftWheelDiameter * (1 - steerRatio));
inside.rotate(_parity * (int) (rotAngle * steerRatio), true);
outside.rotate(_parity * (int) rotAngle, immediateReturn);
if (immediateReturn) {
return;
}
while (inside.isMoving() || outside.isMoving())
// changed isRotating() to isMoving() as this covers what we need
// and alows us to keep the interface small
Thread.yield();
inside.setSpeed(outside.getSpeed());
}
/*
* @return true if either motor actual speed is zero.
*/
public boolean stalled() {
return (0 == _left.getRotationSpeed()) || (0 == _right.getRotationSpeed());
}
/**
* Motors backward. This is called by forward() and backward().
*/
private void bak() {
_left.backward();
_right.backward();
}
/*
* Sets motor speed regulation (default is true).<br> Allows steer() method
* to be called by (for example) a line tracker or compass navigator so
* direction control is from sensor inputs.
*
* @param yes Set motor speed regulation on = true or off = false.
*/
public void regulateSpeed(final boolean yes) {
_regulating = yes;
_left.regulateSpeed(yes);
_right.regulateSpeed(yes);
}
/**
* Motors forward. This is called by forward() and backward().
*/
private void fwd() {
_left.forward();
_right.forward();
}
public void arc(final float radius) {
steer(turnRate(radius));
}
public void arc(final float radius, final float angle) {
steer(turnRate(radius), angle);
}
public void arc(final float radius, final float angle,
final boolean immediateReturn) {
steer(turnRate(radius), angle, immediateReturn);
}
/**
* Calculates the turn rate corresponding to the turn radius; <br>
* use as the parameter for steer() negative argument means center of turn
* is on right, so angle of turn is negative
*
* @param radius
* @return steer()
*/
private float turnRate(final float radius) {
int direction;
float radiusToUse;
if (radius < 0) {
direction = -1;
radiusToUse = -radius;
} else {
direction = 1;
radiusToUse = radius;
}
float ratio = (2 * radiusToUse - _trackWidth)
/ (2 * radiusToUse + _trackWidth);
return (direction * 100 * (1 - ratio));
}
public void travelArc(float radius, float distance) {
travelArc(radius, distance, false);
}
public void travelArc(float radius, float distance, boolean immediateReturn) {
double angle = (distance * 180) / (Math.PI * radius);
arc(radius, (int) angle, immediateReturn); // TODO If Pilot.arc() method
// changes to float for
// angle, get rid of (int)
}
}