When PID controller is used to position control, the higher gain, the better performance. That is why high gain makes error to converge zero fast. But, we cannot use high gain practically. It is related to operation velocity. When motor is operated so fast, high gain brings motor to vibrate. That is the reason input voltage is changed rapidly. Though low gain does not make such a situation, we need minimum velocity to track path in a given time.
The varying gain is the one of the solution. It uses high gain in low velocity and low gain in high velocity. The varying gain does not make vibration and has good responsibility which high gain has. In this thesis, LQR method is used to acquire each PID gains. Also, system identification is carried out simply as soon as possible for auto tuning.
