Parallel Multiple Extended State Observers Based ADRC With Application to High-Speed Precision Motion Stage

In this article, in order to improve the tracking ability of traditional active disturbance rejection control (ADRC) to the reference signal, the parallel multiple extended state observers (multi-ESOs) based ADRC is proposed. First, the way in which the estimation error of the ESO affects the tracking error of closed-loop system is studied, and it is shown that the tracking accuracy is not completely consistent with the estimation accuracy. Next, a novel switching ADRC approach with parallel multi-ESOs is proposed, in which the control law is constructed by automatically selecting different ESOs' estimations from the perspective of reducing tracking error, instead of reducing estimation error. Furthermore, the stability of the proposed algorithm is rigorously proved under some reasonable assumptions. In addition, the proposed ADRC is applied to the high-speed precision motion stage, which has complicated nonlinear uncertainties and elastic deformation disturbances. The experimental results show that the parallel multi-ESOs based ADRC has higher tracking performance than the traditional single ESO based ADRC.