// detect whether hand is within the radius of robot
 private bool isHandWithinRadius(Robot robot, Skeleton skel)
 {
     Point currentPoint = SkeletonPointToScreen(skel.Joints[JointType.HandRight].Position);
     double distance = Math.Sqrt(Math.Pow(currentPoint.X - robot.center.X, 2) + Math.Pow(currentPoint.Y - robot.center.Y, 2));
     if (distance <= robot.radious)
     {
         return true;
     }
     else
         return false;
 }
 // draw the robot
 private void drawRobot(DrawingContext drawingContext, Robot robot)
 {
     drawingContext.DrawLine(robotPen, robot.topLeft, robot.topRight);
     drawingContext.DrawLine(robotPen, robot.topRight, robot.bottomRight);
     drawingContext.DrawLine(robotPen, robot.bottomRight, robot.bottomLeft);
     drawingContext.DrawLine(robotPen, robot.bottomLeft, robot.topLeft);
     drawingContext.DrawLine(robotPen, robot.topLeft, robot.center);
     drawingContext.DrawLine(robotPen, robot.topRight, robot.center);
     drawingContext.DrawLine(robotPen, robot.bottomLeft, robot.center);
     drawingContext.DrawLine(robotPen, robot.bottomRight, robot.center);
     textBox2.Text = "(" + Math.Round(robot.center.X) + " , " + Math.Round(robot.center.Y) + ")";
     textBox3.Text = ""+ Math.Round(robot.angle.angle);
     if (handPath.iterator != null)
         textBox4.Text = "" + Math.Round(handPath.iterator.turnAngle.angle);
 }