Disturbance attenuation–based sliding mode control with disturbance observer for mismatched uncertain system

Jianguo Guo,Jun Zhou,Yuchao Liu,Cheng Cheng

doi:10.1177/1687814017714979

Abstract

A disturbance attenuation–based sliding mode control approach with an extended disturbance observer is proposed for systems with mismatched uncertainties. A novel adaptive sliding surface consisting of the disturbance estimation is presented to eliminate the effect of mismatched disturbance in the sliding mode. The proposed method exhibits the following two attractive features. First, the asymptotical stability of adaptive sliding mode can be guaranteed even if the disturbance estimation error of the disturbance observer exists. Second, the nominal performance of the proposed approach is close to that of the traditional sliding mode control method in the absence of uncertainties. Finally, simulation results of the numerical and application examples show that the proposed nonlinear sliding mode control approach has the better dynamic performance as well as robustness and chattering reduction compared with other nonlinear sliding mode control methods.

Highlights

It is well known that sliding mode control (SMC) is robust to matched uncertainties since it has the property of invariance on the sliding mode in the presence of matched uncertainties and disturbances
Uncertainties existing in control systems may not necessarily satisfy the matching criteria, examples can be seen in a lot of practical systems such as permanent magnet synchronous motors,[3,4] MAGnetic LEVitation (MAGLEV) suspension system,[5] flexible joint manipulator,[6] and control system for missiles.[7,8]
By comparing with the first simulation scenario, it can be observed from Figure 6 that the states of the MAGLEV system for the proposed EDO-ASMC have hardly affected by the mismatched disturbance with time variation, while the states of the system for the disturbance observer (DO)-SMC and the EDOMSMC are severely affected by the mismatched disturbance

Summary

Introduction

It is well known that sliding mode control (SMC) is robust to matched uncertainties since it has the property of invariance on the sliding mode in the presence of matched uncertainties and disturbances. The sliding mode surface for system (1) affected by the mismatched disturbance is designed as follows[5] s = x2 + cx1 + d^ The state in equation (7) cannot be driven to the desired equilibrium point asymptotically based on the sliding mode control with disturbance observer (DO-SMC) law (equation (5)) when the derivation of the disturbance d(t) is bounded and satisfies lim d_ (t) 61⁄4 0.

Results

Conclusion