An Output Feedback Stabilizer for Uncertain MIMO Nonlinear Systems: Nonlinear Nominal Input Gain Function

• Published in: IEEE transactions on automatic control Vol. 68; no. 1; pp. 524 - 531
• Main Authors: Ha, Wonseok, Back, Juhoon
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.01.2023; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Closed loops; Disturbance observers; Disturbance rejection; Feedback control; MIMO communication; multi-input–multi-output (MIMO) system; nonlinear system; Nonlinear systems; Observers; Output feedback; output feedback stabilization; Robust control; State feedback; Uncertainty
• ISSN: 0018-9286; 1558-2523
• DOI: 10.1109/TAC.2022.3144307

This article presents a robust output feedback stabilizer for multi-input-multi-output nonlinear systems subject to external disturbances and system uncertainties. We assume that the system has a well-defined vector relative degree and the zero dynamics is input-to-state stable. Based on the assumption that there exists a state feedback controller that makes the origin of the nominal closed-loop system asymptotically stable, we present an output feedback stabilizer that recovers the stability of the nominal closed-loop system in the practical sense. We allow that the nominal system can have a nonlinear input gain matrix that is a function of system state, and this is done by modifying the structure of the disturbance observer-based robust outputfeedback controller. Simulation results on a practical system are included to validate the proposed controller.