A new configuration of composite nonlinear feedback control for nonlinear systems with input saturation

Abstract

This study proposes a U-control–based Composite Nonlinear Feedback (U-CNF) design procedure. This U-CNF control establishes a double feedback loop framework for generalisation and simplification in designing the CNF control systems. Two controllers, in terms of double dynamic inversion, are designed separately, (1) to stabilise and cancel the nonlinearities and dynamics (convert the plant into an identity matrix) in the inner closed-loop, and then (2) to improve the system transient response by specifying a second-order linear system with a monotonic nonlinear function to smoothly tune the damping ratio. Accordingly, the conventional CNF characteristics in a concise pathway are achieved. The properties show, under proper conditions, the U-CNF control is plant model-free control, applicable to nonaffine nonlinear dynamic systems, and robust against model uncertainty and external disturbance. For the initial bench tests of the first-time proposed U-CNF configuration, the simulated case studies are provided with a transparent procedure to demonstrate the consistency with the analytical results in the numerical computations and to present guidance for applications.

Addressing asymmetric saturation in chaotic Chua's circuit switched system: A combined adaptive sliding mode strategy

“…As the output approaches the desired targets, a nonlinear feedback law comes into play, allowing for damping ratio regulation and minimizing the overshoot induced by the linear component. 11,12 The Sliding mode control approach (SMCA), which belongs to the category of variable structure control systems, is widely used as a switching system control technique. SMCA has been adopted as a mighty control method to mitigate the effects of ambiguities and disturbances.…”

Observer-based integral controller using composite nonlinear feedback for saturated control systems

“…The output regulation is addressed in the semi-global sense for the linear systems (Wang et al, 2014). Henceforth, it is extended to the discrete-time (Venkataramanan et al, 2003), singular (Lin et al, 2011), switching dynamic (Mobayen and Tchier, 2018), delayed system (Ghaffari, 2020b; Ghaffari et al, 2022), strict-feedback (Lu and Lan, 2019), and nonlinear representations (Zhu et al, 2022). The CNF control is suggested in the output-feedback configuration for saturated descriptor systems (Lin and Lan, 2015).…”

Robust integral controller design based on composite nonlinear feedback in uncertain systems with constrained inputs and external disturbances

“…Then, discrete‐time CNF control law is evaluated in a servo system consisting hard disk drive (HDD) 2 . A new structure of the CNF is studied in constrained nonlinear control systems 3 . The CNF idea is applied to singular control systems 4,5 .…”

“…2 A new structure of the CNF is studied in constrained nonlinear control systems. 3 The CNF idea is applied to singular control systems. 4,5 However, the CNF idea may be helpful in cases with non-step and time-varying references.…”