This paper proposed a discrete-time extended sliding mode observer (ESMO) to reduce the influence of load thrust mutation on the linear motor and improve the anti-interference ability of the system. First, the electrical model and dynamic model of linear motor are established. Second, the extended state equation of velocity and load thrust is given, and the error between the actual velocity and the observed velocity is selected as the sliding mode surface. Then, an adaptive discrete-time piecewise reaching law is designed to establish the extended sliding mode observer. The observed load thrust is compensated to the controller in the form of feedforward. Finally, a series of comparative experiments were carried out to verify the effectiveness and correctness of the proposed method.

sliding mode control Load observer