Servo control system, as one of the control systems of modern industrial production equipment, is an indispensable basic technology to realize industrial automation. Position servo control system generally takes enough position control accuracy (positioning accuracy), position tracking accuracy (position tracking error) and enough fast tracking speed as the main control objectives. When the system is running, it is required to be able to track the change of instructions with a certain precision at any time, so the running speed of the servo motor in the system is always changing. Therefore, the tracking performance of servo system is generally higher and stricter than that of ordinary speed control system. Because of the limitation of dc motor brush and commutator, and the high production and maintenance cost of DC servo system. With the emergence of new control devices and motor control methods, servo system has widely replaced dc servo system.