v_swirl_vv.java

一个多机器人的仿真平台

/*
 * v_Swirl_vv.java
 */

package EDU.gatech.cc.is.clay;

import java.lang.*;
import EDU.gatech.cc.is.util.Vec2;
import EDU.gatech.cc.is.util.Units;

/**
 * Generate a vector that swirls to one side or the other of a detected hazard.
 * One embedded node provides a hazard to avoid, the other points 
 * in the reference direction (typically a goal location).
 * <P>
 * The "swirl" behavior was originally developed by
 * Andy Henshaw and Tom Collins at the Georgia Tech Research Institute.  
 * It is also similar to Marc Slack's NATs.
 * <P>
 * For detailed information on how to configure behaviors, see the
 * <A HREF="../clay/docs/index.html">Clay page</A>.
 * <P>
 * <A HREF="../COPYRIGHT.html">Copyright</A>
 * (c)1997, 1998 Tucker Balch
 *
 * @author Tucker Balch
 * @version $Revision: 1.1 $
 */

public class v_Swirl_vv extends NodeVec2
	{
	/**
	Turn debug printing on or off.
	*/
	public static final boolean DEBUG = Node.DEBUG;
	private NodeVec2	embedded1;
	private NodeVec2	embedded2;
	private double		sphere = 1.0;
	private double	        safety = 0.0;

	/**
	Instantiate a v_Swirl_vv schema.
	@param soe double, the sphere of influence beyond which the hazards
		are not considered.
	@param s double, the safety zone, inside of which a maximum repulsion
		from the object is generated.
	@param im1 double, the embedded perceptual schema that generates an
		item to avoid.
	@param im2 double, the embedded perceptual schema that generates a pointer
		to the goal (must be egocentric).
	*/
	public v_Swirl_vv(double soe, double s,
		NodeVec2 im1, NodeVec2 im2)
		{
		if (DEBUG) System.out.println("v_Swirl_vv: instantiated.");
		embedded1 = im1;
		embedded2 = im2;
		if ((soe < s) || (soe<0) || (s<0))
			{
			System.out.println("v_Swirl_vv: illegal parameters");
			return;
			}
		sphere = soe;
		safety = s;
		}


	Vec2	last_val = new Vec2();
	long	lasttime = 0;
	/**
	Return a Vec2 representing the direction to go.
	@param timestamp long, only get new information if timestamp > than last call
                or timestamp == -1.
	@return the movement vector.
	*/
	public Vec2 Value(long timestamp)
		{
		double	tempmag;
		double	tempdir;
		double	refheading;

		if ((timestamp > lasttime)||(timestamp == -1))
			{
			/*--- reset the timestamp ---*/
			if (timestamp > 0) lasttime = timestamp;

			/*--- reset output ---*/
			last_val.setr(0);

			/*--- get the obstacle and ref dir ---*/
			Vec2 obs = embedded1.Value(timestamp);
			refheading = embedded2.Value(timestamp).t;

			/*--- consider each obstacle ---*/
			// only swirl around the obs if it is
			// in front of us.
			tempdir = -Units.BestTurnRad(refheading,
				obs.t);
			if (Math.abs(tempdir)<Math.PI/2)
				{
				/*--- compute direction of swirl ---*/
				// first decide left or right, negative 
				// is right
				if (tempdir < 0)
					obs.sett(obs.t - Math.PI/2);
				else
					obs.sett(obs.t + Math.PI/2);
				
				/*--- compute magnitude of swirl ---*/
				// inside saftey zone, set full magnitude
				if (obs.r < safety)
					{
					tempmag = 1;
					}
				// in controlled zone
				else if (obs.r < sphere)
					tempmag = (sphere - obs.r)/
						(sphere - safety);
				// outside sphere of influence, ignore
				else tempmag = 0;
				// set the magnitude
				obs.setr(tempmag);

				/*--- add it to the sum ---*/
				if (DEBUG) System.out.println(obs);
				last_val.add(obs);
				}
			/*--- normalize ---*/
			//NOT!
			//if (last_val.r > 0)
			//	last_val.setr(0.0);
			if (DEBUG) System.out.println("v_Swirl_vv.Value: "+
				"output "+
				last_val);
			}
		return (new Vec2(last_val.x, last_val.y));
		}
        }