Robust Output Feedback Passivity-Based Variable Structure Controller Design for Nonlinear Systems

Jeang-Lin Chang,Tsui-Chou Wu

doi:10.1155/2019/9156261

Abstract

This paper examines the use of an output feedback variable structure controller with a nonlinear sliding surface for a class of SISO nonlinear systems in the presence of matched disturbances. With only the measurable system output, the discontinuous observer reconstructs the system states and ensures that the estimation errors exponentially approach zero. Using the estimation states, the proposed nonlinear sliding surface with variable damping ratio can simultaneously achieve low overshoot and short settling time. Then the passivity-based controller including a discontinuous term can guarantee that the closed-loop system asymptotically converges to the sliding surface. Compared with other sliding mode controllers, the proposed passivity-based control scheme has better transient performance and effectively reduces the control gain. Finally, simulation results demonstrate the validity of the proposed method.

Highlights

Variable structure control or sliding mode control [1, 2] utilizing a discontinuous control term to drive the plant onto a predesigned surface is a popular robust control method for nonlinear systems with unknown disturbances
This paper develops a robust passivity-based variable structure control method for a class of nonlinear systems with matched unknown disturbances based on the estimation information
For single input single output (SISO) nonlinear systems with matched disturbances, an output feedback variable structure controller with the nonlinear sliding surface has been proposed in this paper

Summary

Introduction

Variable structure control or sliding mode control [1, 2] utilizing a discontinuous control term to drive the plant onto a predesigned surface is a popular robust control method for nonlinear systems with unknown disturbances. This paper develops a robust passivity-based variable structure control method for a class of nonlinear systems with matched unknown disturbances based on the estimation information. This discontinuous observer can make the dynamics of estimation error satisfy a strictly positive real lemma. If the system is subjected to matched disturbances, it is shown that the closed-loop system can be asymptotically stabilized The advantage of this approach is that it addresses the problem of designing a controller and the proposed control method overcomes the constraint of input saturation. According to the estimation information, the nonlinear sliding surface with the variable damping ratio is proposed and the passivity-based variable structure control algorithm is developed .

Problem Formulation

Robust Output Feedback Variable Structure Controller Design

Numerical Example

Conclusion