Adaptive observer-based control of arbitrarily switched fractional-order uncertain nonlinear system subject to input nonlinearities and asymmetric output constraints

• Published in: Nonlinear analysis. Hybrid systems Vol. 50; p. 101405
• Main Authors: Malek, Sayyed Alireza, Shahrokhi, Mohamad
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.11.2023
• Subjects: Input nonlinearity; Intelligent approximator; State estimation; Switched fractional-order systems; Time-varying output constraints; Unknown arbitrary switching; Input nonlinearity; Switched fractional-order systems; Intelligent approximator; State estimation; Unknown arbitrary switching; Time-varying output constraints
• ISSN: 1751-570X
• DOI: 10.1016/j.nahs.2023.101405

This paper addresses an adaptive observer-based control for a switched fractional-order uncertain nonlinear system subject to input nonlinearities and asymmetric output constraints. The switching signal is arbitrary, and the designed controller needs no information regarding this signal. By employing a universal framework, the designed controller can cope with different input nonlinearities in different modes without having any information about their characteristics. It is assumed that only system output is measured, and a designed observer estimates the system states for control implementation. The uncertainties are approximated by intelligent approximators like fuzzy logic systems (FLS) or neural networks (NN). The time-varying asymmetric output constraints have been satisfied using a common barrier Lyapunov function (BLF). Using the common Lyapunov function (CLF) method and the backstepping control technique, the virtual controllers, adaptive law and control input have been designed, and the boundedness of closed-loop signals has been guaranteed. The effectiveness of the designed control scheme has been demonstrated through a numerical and two practical simulation examples. •Observer-based controller for switched fractional order sy stems has been designed.•The nonlinear system is subject to input nonlinearity and output constraints.•To reduce the computational load only one adaptive law has been used.•Two CSTRs with asymmetric time-varying output constraints have been simulated.