Control strategy for networked control systems with time delay and packet dropout using linear matrix inequalities

Zhaohong Wang,Seiji Fukushima

doi:10.1186/s13638-019-1556-4

Zhaohong Wang, Seiji Fukushima

Open Access

https://doi.org/10.1186/s13638-019-1556-4

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Abstract

A control strategy using linear matrix inequalities towards time delay and stochastic packet dropout of networked control system is proposed in this paper. First, a reconfigured target plant of networked control system is built based on a linear time-invariant target. Before discretization of target plant, a Pade approximation is employed towards the time delay segment of reconfigured target plant, while zero-order holder compensator and an estimator are employed for packet dropout of control input and measured output, respectively. Then the control target is reformed as a programming problem of an uncertain time-variant multi-parametric state space. In order to deal with such problem, herein the time-variant state space is rewritten as a linear parametric-varying prediction model by enumerating all possible occasions. Afterwards, a novel robust model predictive controller is proposed as a constrained minimax optimization of the predictive cost function. Finally, we present two simulations based on an aircraft model and a second-order numeric model, by which step responses and explicit solutions are derived, performed and analysed. Simulation results demonstrate both the stability and robustness of the proposed control strategy.

Highlights

Alongside of the development of Internet of Things (IoT), we have paid more and more attention to networked control systems (NCSs), wherein the closed control loops are connected via networks [1]
6 Conclusion We have proposed a novel model predictive controller towards networked control systems featured with time delay and packet dropout in this paper
Target plant and network are reconstructed and reformed into a reconfigured target plant, in the modelling process, segments of time delay are eliminated by Pade approximation; a zeroorder holder-like compensator is utilized for packet dropout in control input, packet dropout in the measured output is compensated by estimation

Summary

Introduction

Alongside of the development of Internet of Things (IoT), we have paid more and more attention to networked control systems (NCSs), wherein the closed control loops are connected via networks [1]. We have to beware of two main defects that networked control systems may have: problems such as time delay and packet dropout. Time delay and packet dropout can be Research on NCSs is generally categorized into two aspects: control of network and control over network. Control over network pays more attention to control strategies and control systems design over the network to enhance the performance of control system against packet dropout, time delay, etc. Torres et al have considered a networked control system with time delayed less than sampling period, the application area of which is limited and the study is more concerning over modelling [5]. A modified preview control for a wireless tracking control system with packet loss is proposed by [11] in need of some deterministic future segment while most NCSs in reality have only stochastic future

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Results

Conclusion