Output feedback control for unknown LTI systems driven by unknown periodic disturbances. (January 2019)

• Record Type: Journal Article
• Authors: Yilmaz, Cemal Tugrul; Basturk, Halil Ibrahim
• Is Part Of: Automatica. Volume 99(2019)
• Page Start: 112
• Page End: 119
• Publication Date: 2019-01
• Subjects: Adaptive control -- Uncertain linear time invariant system -- Output feedback -- Multiharmonic disturbance rejection; Automatic control -- Periodicals; Automation -- Periodicals; 629.805
• DOI: 10.1016/j.automatica.2018.10.020
• Languages: English
• ISSNs: 0005-1098

Abstract

Abstract: This paper considers unknown minimum-phase LTI systems with known relative degree and system order. The main aim is to reject the unknown, unmatched sinusoidal disturbances and make the output track a given trajectory with the output feedback. The essence of the control design is composed of disturbance parametrization, K-filter technique and adaptive backstepping procedure. Firstly, the unmeasured system states are represented in terms of filtered input and output signals. Then, the disturbance information in the output signal is parametrized and the problem is converted to an adaptive control problem. After that, the K-filter approach is employed to redefine the system states that enable to use a backstepping technique. An adaptive output feedback controller is designed recursively. It is proven that the equilibrium at the origin is globally uniformly stable and the output signal tracks the reference signal asymptotically. Finally, the effectiveness of the controller is illustrated with a numerical simulation. The robustness of the closed loop system with respect to an additive unmodelled noise is also discussed.