Active Disturbance Rejection Control for Discrete Systems

A form of active disturbance rejection control (ADRC) is proposed for a kind of discrete systems in this paper. The state space form of the system is firstly formulated. Then the extended state observers (ESO) with and without model information are presented to estimate states and total disturbance. The control law is formulated to reject disturbance and to track a given trajectory. As a case study, the semiconductor manufacturing process is used to validate the proposed solution. Comparing with the exponentially weighted moving average controller, simulations indicate that the proposed discrete ADRC is effective in cancelling disturbance and in tracking the desired target.