Robust output regulation of minimum phase nonlinear systems using conditional servocompensators

Abstract

SUMMARYWe consider the design of a robust continuous sliding mode controller for the output regulation of a class of minimum-phase nonlinear systems. Previous work has shown how to do this by incorporating a linear servocompensator in the sliding mode design, but the transient performance is degraded when compared to ideal sliding mode control. Extending previous ideas from the design of 'conditional integrators' for the case of asymptotically constant references and disturbances, we design the servocompensator as a conditional one that provides servocompensation only inside the boundary layer; achieving asymptotic output regulation, but with improved transient performance. We give both regional as well as semi-global results for error convergence, and show that the controller can be tuned to recover the performance of an ideal sliding mode control.

DC/DC Buck Converter Using Internal Model Control

“…If an internal model exists, the robust output regulation can be converted to the robust stabilization problem of an augmented system consisting of the original plant and the internal model, that is, to design a proper controller to guarantee the asymptotic stability of the closedloop system [9]. Apparently, the solvability of this problem relies on the success in addressing two key issues.…”

“…Based on the conditional integrator [7] of the internal model, the robust output regulation of the buck converter is solved by designing a sliding-mode robust controller for an augmented system, which consists of the given converter and the internal model [8,9]. This scheme is simple to implement, and precise system parameters are not required.…”

Robust output regulation of single-switch quadratic buck converter using internal model

“…If an internal model exists for the quadratic buck converter, the robust output voltage regulation can be converted into the robust stabilization problem of an augmented system consisting of the converter and the internal model [9].…”

“…In this paper, internal model control with conditional integrator is proposed for the fast and robust output regulation of single-switch quadratic buck converters. The design is composed of the derivation of an internal model [7] with conditional integrator for the quadratic buck converter and the design of a robust sliding stabilizer for the internal model [8,9]. The proposed control scheme can be implemented with simple analogue circuitry.…”

Output regulation for switched linear systems with different coordinate transformations

“…The problem for non-switched linear systems was widely studied in [10]- [12]. For non-switched nonlinear systems, there are also many results for the problem [13]- [15].…”