Active disturbance rejection for time-varying state-delay systems based on equivalent-input-disturbance approach

Meiliu Li; Jinhua She; Chuan-Ke Zhang; Zhen-Tao Liu; Min Wu; Yasuhiro Ohyama

doi:10.1016/j.isatra.2020.09.001

Active disturbance rejection for time-varying state-delay systems based on equivalent-input-disturbance approach

ISA Trans. 2021 Feb:108:69-77. doi: 10.1016/j.isatra.2020.09.001. Epub 2020 Sep 14.

Authors

Meiliu Li¹, Jinhua She², Chuan-Ke Zhang¹, Zhen-Tao Liu¹, Min Wu¹, Yasuhiro Ohyama³

Affiliations

¹ School of Automation, China University of Geosciences, Wuhan 430074, China; Hubei Key Laboratory of Advanced Control and Intelligent Automation for Complex Systems, Wuhan 430074, China.
² School of Automation, China University of Geosciences, Wuhan 430074, China; Hubei Key Laboratory of Advanced Control and Intelligent Automation for Complex Systems, Wuhan 430074, China; School of Engineering, Tokyo University of Technology, Hachioji, Tokyo 192-0982, Japan. Electronic address: she@stf.teu.ac.jp.
³ School of Engineering, Tokyo University of Technology, Hachioji, Tokyo 192-0982, Japan.

PMID: 32958295
DOI: 10.1016/j.isatra.2020.09.001

Abstract

Exogenous disturbances largely affect the control performance of systems with time delays. This study considers a control problem of rejecting a disturbance in a PI control system for a time-varying state-delay plant. The equivalent-input-disturbance (EID) approach is integrated in a PI control system. An EID estimator estimates the overall effects of a time-varying delay and a disturbance. An EID estimate is combined into a PI control law to improve control performance. A less-conservative stability condition of the control system is derived using a Lyapunov-Krasovskii functional together with the Jensen's integral inequality and the reciprocally convex combination lemma. Parameters of the controllers in the system are calculated using the condition. Engine idle speed control is used to verify the effectiveness of this approach. Compared with the generalized extended-state observer and the sliding-mode control methods, our method reduced the tracking error to about one third and one sixth, respectively. This demonstrates the validity and superiority of our method.

Keywords: Disturbance estimation; Equivalent input disturbance (EID); Jensen’s integral inequality; PI control; Reciprocally convex combination lemma; State delay.