Package lejos.robotics.objectdetection

Class TouchFeatureDetector

java.lang.Object

lejos.robotics.objectdetection.FeatureDetectorAdapter

lejos.robotics.objectdetection.TouchFeatureDetector

All Implemented Interfaces:

FeatureDetector

public class TouchFeatureDetector
extends FeatureDetectorAdapter

This class allows a touch sensor to be used as a defacto range sensor by reporting the position of the touch sensor to the object detection API. The touch sensor will only notify one time when it is pressed and will not be ready to notify again until the touch sensor is released.

Field Summary

Fields

Modifier and Type	Field and Description
private float	angle
private static int	DELAY
private java.util.ArrayList<FeatureListener>	listeners
private float	range
private Touch	touch_sensor

Constructor Summary

Constructors

Constructor and Description
TouchFeatureDetector(Touch touchSensor) Creates a touch detector in which the touch sensor is assumed to be situated in the center of the robot.
TouchFeatureDetector(Touch touchSensor, double xOffset, double yOffset) If you want the bumpers to report contact relative to the geometry of where they are placed on the robot, you can provide the x, y offsets of each bumper relative to the center of the robot (the center is the halfway point between the drive wheels).

Method Summary

Modifier and Type	Method and Description
protected void	notifyListeners(Feature feature)
Feature	scan() Performs a single scan for an object and returns the results.

Methods inherited from class lejos.robotics.objectdetection.FeatureDetectorAdapter

addListener, enableDetection, getDelay, isEnabled, setDelay

Methods inherited from class java.lang.Object

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

Field Detail

touch_sensor

private Touch touch_sensor

angle

private float angle

range

private float range

DELAY

private static final int DELAY

See Also:

Constant Field Values

listeners

private java.util.ArrayList<FeatureListener> listeners

Constructor Detail

TouchFeatureDetector

public TouchFeatureDetector(Touch touchSensor)

Creates a touch detector in which the touch sensor is assumed to be situated in the center of the robot. This is fine in situations where the robot only needs to react to a bumper contact. See the alternate constructor if more than one bumper is located around the robot.

Parameters:

touchSensor - The touch sensor bumper.

TouchFeatureDetector

public TouchFeatureDetector(Touch touchSensor,
                            double xOffset,
                            double yOffset)

If you want the bumpers to report contact relative to the geometry of where they are placed on the robot, you can provide the x, y offsets of each bumper relative to the center of the robot (the center is the halfway point between the drive wheels). Most bumpers are planar, so generally you would use the center of the bumper as the contact point.

Parameters:

touchSensor - The touch sensor bumper.

xOffset - The offset (in units e.g. cm) left or right of center. Right is positive, left is negative.

yOffset - The offset (in units e.g. cm) forward or back of center. Forward is positive, back is negative.

Method Detail

scan

public Feature scan()

Description copied from interface: FeatureDetector

Performs a single scan for an object and returns the results. If an object is not detected, this method returns null.

Warning: Make sure to check for a null object before trying to read data from the returned Feature object, otherwise your code will throw a null pointer exception.

Specified by:

scan in interface FeatureDetector

Specified by:

scan in class FeatureDetectorAdapter

Returns:

A feature it has detected. null if nothing found.

notifyListeners

protected void notifyListeners(Feature feature)

Overrides:

notifyListeners in class FeatureDetectorAdapter