Why is the head jumping around the body?

Question

I wrote the following code for Head which should follow the body like a spring. I added friction so the head will stop bouncing sometime but no success. The head keeps jumping near the beggining of the spring (which is the beggining of the body) and not stopping. What should I do to make the head stop at some time?
  final static int MASS = 10;
  final static int FRICTION = 100;
  private final double hardness = 3;
public void followBody(Body body) {
double[] coards = getCoardinatesBy(getRadius(), body.getXCoardStart(), body.getYCoardStart(), 180+body.getAngel()); // get the coordinates of the beginning of the spring (where should the head be in the end
        coards[0] -= getRadius();
        coards[1] -= getRadius();
        if (getYSpeed() < 0) {
            this.setYAcceleration((getYForce(coards[1]) + FRICTION)/MASS);
        } else if (getYSpeed() > 0) {
            this.setYAcceleration((getYForce(coards[1]) - FRICTION)/MASS);
        } else if (Math.abs(getYForce(coards[1])) < FRICTION ) { //static friction, equal to the power or less
            this.setYAcceleration(0);
        } else {
            this.setYAcceleration(getYForce(coards[1]) / MASS); // speed is zero. new the head is far away from the spring
        if (getXSpeed() < 0) {
            this.setXAcceleration((getXForce(coards[0]) + FRICTION)/MASS);
        } else if (getXSpeed() > 0) {
            this.setXAcceleration((getXForce(coards[0]) - FRICTION)/MASS);
        } else if (Math.abs(getXForce(coards[0])) < FRICTION) { // static friction, equal to the power or less
            this.setXAcceleration(0);
        } else {
            this.setXAcceleration(getXForce(coards[0]) / MASS); // speed is zero. new the head is far away from the spring
   double getYForce(double y){
        return hardness*(y-yCoardStart);
    double getXForce(double x){
        return hardness*(x-xCoardStart);
static double[] getCoardinatesBy(double height, double startX, double startY, double angel) {
        double[] coardinates = new double[2];
        coardinates[1] = startY - (height * Math.sin((Math.toRadians(angel))));
        coardinates[0] = startX + (height * Math.cos(Math.toRadians(angel)));
        return coardinates;
  public void update() {
        xSpeed += xAcc;
        ySpeed += yAcc;
        xCoardStart += xSpeed;
        xCoardEnd += xSpeed;
        yCoardEnd += ySpeed;
        yCoardStart += ySpeed;
        angularVelocity+=angularAcc;
        this.angel += angularVelocity;
        autoSetEndXY();
private void autoSetEndXY() {
        double[] coards = getCoardinatesBy(height, xCoardStart, yCoardStart, angel);
        yCoardEnd = coards[1];
        xCoardEnd = coards[0];
    }Edited by: Vitali.pom on May 20, 2012 6:01 AM
Edited by: Vitali.pom on May 29, 2012 12:19 AM
Edited by: Vitali.pom on Jun 26, 2012 12:05 PM

Answer 1

Thanks for the try. That's what I tried:
public void followBodyPart(BodyPart body) {
        double[] coards = getCoardinatesBy(getRadius(), body.getXCoardStart(), body.getYCoardStart(), 180+body.getAngel());
        coards[0] -= getRadius();
        coards[1] -= getRadius();
       if (getYSpeed() < 0) {
            this.setYAcceleration((getYForce(coards[1]) + FRICTION)/MASS);
        } else if (getYSpeed() > 0) {
            this.setYAcceleration((getYForce(coards[1]) - FRICTION)/MASS);
            System.out.println("Player moved.");
        } else if (Math.abs(getYForce(coards[1])) < FRICTION) {
            this.setYAcceleration(0);
            System.out.println("y force is 0.");
        } else {
            this.setYAcceleration((getYForce(coards[1]))/ MASS);
        if (getXSpeed() < 0) {
            this.setXAcceleration((getXForce(coards[0]) + FRICTION)/MASS);
        } else if (getXSpeed() > 0) {
            this.setXAcceleration((getXForce(coards[0]) - FRICTION)/MASS);
            System.out.println("Player moved.");
        } else if (Math.abs(getXForce(coards[0])) < FRICTION) {
            this.setXAcceleration(0);
            System.out.println("x force is 0.");
        } else {
            this.setXAcceleration((getXForce(coards[0]))/ MASS);
    }And that's what I got (repeating in the end):
Player moved.
y force is 0.
y force is 0.
Player moved.
y force is 0.
y force is 0.
Player moved.
y force is 0.
Player moved.
Player moved.
Player moved.
Player moved.
Player moved.
Edited by: Vitali.pom on Jun 16, 2012 3:54 AM