Chattering-Free Sliding Mode Control for Networked Control System with Time Delay and Packet Dropout Based on a New Compensation Strategy

Yu Zhang,Ledi Zhang,Bin Zhou,Litong Ren,Hao Wang,Shousheng Xie

doi:10.1155/2019/1016381

Abstract

This paper addresses the sliding mode control problem for a class of networked control systems with long time delay and consecutive packet dropout. A new modeling method is proposed, through which time delay and packet dropout are modeled in a unified model described by one Markov chain. To avoid the chattering problem of classic reaching law, a new chattering-free reaching law is proposed. Then with a focus on the problem that controller-actuator channel network condition cannot be foreseen by the controller, a new compensation strategy is proposed, which can effectively compensate for the effect of time delay and packet dropout in controller-actuator channel. Finally, a simulation example is presented to demonstrate the effectiveness of the proposed approach.

Highlights

In recent years, a lot of interest and concern have been focused on networked control systems (NCSs) where communication channels interconnect sensors with controllers and/or controllers with actuators [1]
Motivated by the above discussions, this paper focuses on proposing a new model that considers both long time delay and consecutive packet dropout in a unified model, and the situation of actual received control signals on the actuator side will be considered to avoid problems like packet disordering and the use of obsolete data
If τ(k + 2) = 2, since time delay is bounded, at time instant k + 3, the late arriving signal could only be u(k + 1) or u(k + 2), and if there is still no newly arrived signal, it is certain that packet u(k + 1) and the signals sent before k + 1, if still not received, are already lost

Summary

Introduction

A lot of interest and concern have been focused on networked control systems (NCSs) where communication channels interconnect sensors with controllers and/or controllers with actuators [1]. It is discovered that most of the existing Markov chain based modeling methods have a common problem that the time delay and packet dropout are usually considered on the controller side, which means they do not reflect the condition of the packets received by the actuator This could lead to the problem of the use of outdated signals and packet disordering. With a focus on this problem, this paper proposes a chattering-free sliding mode reaching law for a type of multiple-input NCSs, and it needs to be pointed out that, to the best of the author’s knowledge, the use of such chattering-free reaching law in multiple-input systems has rarely been reported Another critical problem usually ignored is that the network condition of the controller-actuator channel cannot be foreseen by the controller when calculating the control signal, which makes the calculated control signal not suitable for the systems when there exists time delay or packet dropout.

A New Modeling Method for NCSs with Time Delay and Packet Dropout

Design of Chattering-Free Sliding Mode Controller

Simulation Example

Conclusion