Lyapunnov stable control of tubular linear permanent-magnet motor

This paper presents a novel design of a lightweight tubular linear brushless permanent-magnet motor with Lyapunnov stable control algorithm. In this design, the magnets in the moving part are oriented axially in an NS-iron-SN-iron-NS array which leads to a higher magnetic force near the pole. An analytical method to derive the commutation equation relating thrust force and current based on position was presented. The Lyapnnov stable control is presented and an equilateral triangle acceleration-deceleration algorithm is used to define the velocity. The performance of the Lyapnnov stable control is examined experimentally, the results clearly demonstrate the motor has more accuracy tracking ability. Contrasting to the classical cascade controller the Lyapunnov-stable control supplies an excellent robustness property and higher tracking accuracy. It is very suitable for a motion system with variable load to track a desired control input.