Extended State Observer Based Output Feedback Asymptotic Tracking Control of DC Motors

Modeling uncertainties and measurement noise in physical servo systems severely deteriorate their tracking performance. In this paper, an output feedback control strategy which integrates a discontinuous robust control with extended state observer via feed-forward cancellation technique is proposed for high precision motion control of a dc motor. The designed extended state observer can estimate the unmeasured system state and the modeling uncertainties simultaneously. Since the vast majority of the modeling uncertainties can be estimated by the extended state observer and then compensated in the controller design, the task of robust control can be greatly alleviated which prevents the discontinuous output feedback controller from chattering. In addition, the proposed controller theoretically achieves an asymptotic output tracking performance even in the presence of modeling uncertainties, which is rather significant for high precision control of motion systems. Extensive comparative simulation results are provided to verify the high performance nature of the proposed control strategy.