Discrete Second-Order Sliding Mode Adaptive Controller Based on Characteristic Model for Servo Systems

Zhihong Wang,Yifei Wu,Xiang Wang,Qingwei Chen,Wei Chen,Jian Guo

doi:10.1155/2015/405376

Zhihong Wang, Yifei Wu + Show 4 more

Open Access

https://doi.org/10.1155/2015/405376

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Abstract

Considering the varying inertia and load torque in high speed and high accuracy servo systems, a novel discrete second-order sliding mode adaptive controller (DSSMAC) based on characteristic model is proposed, and a command observer is also designed. Firstly, the discrete characteristic model of servo systems is established. Secondly, the recursive least square algorithm is adopted to identify time-varying parameters in characteristic model, and the observer is applied to predict the command value of next sample time. Furthermore, the stability of the closed-loop system and the convergence of the observer are analyzed. The experimental results show that the proposed method not only can adapt to varying inertia and load torque, but also has good disturbance rejection ability and robustness to uncertainties.

Highlights

The growth and development of our modern society is heavily dependent on the development, sustenance, and improvement of control systems
The results indicate that the characteristic model can properly describe the electromechanical system
It is noticed that in some cases the periodical error jumps of the proposed controller are larger than those of the typical sliding mode controller such as in Figures 8(a) and 8(b); that is because the peak error jumps are caused by backlash which can lead to a speed jump when the gears go across the backlash, and the chattering of the typical sliding mode controller makes the

Summary

Introduction

The growth and development of our modern society is heavily dependent on the development, sustenance, and improvement of control systems. To improve the performance of the controller under conditions of backlash, friction, and variable inertia and load torque, we should find a SMC with good adaptive ability. A novel adaptive discrete second-order sliding mode controller based on characteristic model is proposed, and a command observer is adopted to predict command value. Experimental results show that the proposed method can obtain good performance in servo systems with varying inertia and load torque and has good adaptive ability and robustness.

Problem Description and System Modeling

Controller Design and Stability Analysis

System Experiment

Conclusions