Active disturbance rejection control for PMLM servo system in CNC machining

Uncertain friction is a key factor that influences the accuracy of servo system in CNC machine. In this paper, based on the principle of Active Disturbance Rejection Control (ADRC), a control method is proposed, where both the extended state observer (ESO) and the reduced order extended state observer (RESO) are used to estimate and compensate for the disturbance. The authors prove that both approaches ensure high accuracy in theory, and give the criterion for parameters selection. The authors also prove that ADRC with RESO performs better than that with ESO both in disturbance estimation and tracking error. The simulation results on CNC machine show the effectiveness and feasibility of our control approaches.