public void keyReleased(KeyEvent e){
		if(e.getKeyChar() == 'a' && turn_state == JRaceCar.LEFT){
			turn_state = 0;
		}
		else if(e.getKeyChar() == 'd' && turn_state == JRaceCar.RIGHT){
			turn_state = 0;
		}
		else if(e.getKeyChar() == 'w' && accelerate_state == 1){
			accelerate_state = 0;
		}
		else if(e.getKeyChar() == 's' && accelerate_state == -1){
			accelerate_state = 0;
		}
	}