Networked control systems with probabilistic time-varying delay based on event-triggered non-fragile [formula omitted] control

A new model for networked control systems (NCSs) with structured uncertainties and multiple state time-delays is presented, In view of multi-input and multi-output (MIMO) NCSs with many independent sensors and actuators, a continuous time model of NCSs with distributed time-delays and uncertainties are proposed. A method of delay-estimation online is also given. Then a scheme based on LQG controller is designed to achieve desired Real-time performance. The result illustrate that the effectiveness of the proposed control design and the satisfactory performance of the system.

Controller synthesis for networked control systems

Networked control systems (NCS) are in existence for quite some time. The network-induced delays and packet drops; and their effect on control system's performance has been a burning topic for last one decade. Dependability in context of NCS has not got much attention. While it is an important aspect of NCS intended to be used in critical application. The paper reviews the present state of developments in NCS and presents open problems pertaining to dependability of NCS. Solutions to these problems may increase the presence of NCS by many folds and in many fields.

This paper studies the non-fragile output-feedback control problem for event-triggered networked control system with probabilistic time-varying delay and controller gain uncertainties. With known conditional probability distribution, the time-varying delay is modelled as a Bernoulli distributed white sequences. An improved two-side closed-loop functional is constructed by using the sawtooth structure characteristic of artificial time delay. By applying the Lyapunov–Krasovskii stability theory, the lower conservative stability criterions for time-delay system are derived. Aiming at the external disturbance and the parameter uncertainty of controller gain, a non-fragile output-feedback control strategy based on event-triggered mechanism is proposed. Moreover, a co-design scheme of controller gain and event-triggered matrix is obtained based on linear matrix inequality technique. Finally, three simulation examples are utilised to verify the effectiveness of the presented method.

Research on mean square exponential stability of networked control systems with multi-step delay

Based on the controlled process that is linear time-invariant system, the network-induced long time delay is viewed as time-varying parameter uncertainties. The uncertainty parameters model of networked control systems with long time delay is set up. The existing conditions of asymptotic stability for networked control system with long time delay are presented by Lyapunov method and robust control theory. The design method of stabilization controller for networked control system is proposed in terms of linear matrix inequalities. In the end the simulation based on the networked control unstable system is studied. The simulation results show the proposed controller is feasible and effective.

NCSWT: An integrated modeling and simulation tool for networked control systems

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A mathematical model of networked control systems (NCS) with dynamic controllers is presented when the network-induced random time-varying delays of NCS are bounded and the upper bound of which is longer than one sampling period. This paper discretizes the model of continuous-time systems, applies augmented state-space method to the model and builds a discrete-time jump system model governed by a finite state Markov process. And the necessary and sufficient conditions guaranteeing stability of the system are discussed. This paper applies interior-point algorithm to design stabilizing controllers, presents a method to get the feasible initial solution and replaces Newton direction which is generally used in the interior-point algorithm with conjugate gradient direction for simplifying the algorithm. And this improved algorithm stated above is applied effectively to the networked control system of a cart and inverted pendulum with long delays.

In this paper, finite horizon optimal control and communication co-design problem has been investigated for uncertain networked control system (NCS) with limited transmit power. Firstly, the mathematical relation between network imperfections (e.g. network-induced delays and packet dropouts) and practical wireless communication channel quality has been studied. Then, a novel networked control system model has been represented that includes both physical system dynamics and network dynamics. Next, adopting the emerging neuro dynamics programming (NDP) technique and actor-critic-identifier (ACI) architecture, a novel time-based finite horizon optimal control and communication co-design has been proposed. The proposed scheme cannot only learn the optimal co-design within fixed final time, but also relax the requirement of NCS dynamics and satisfy the practical transmit power constraint. The Lyapunov Theorem is used to validate the effectiveness of proposed scheme. With the proper NN weight update law, proposed scheme can ensure all closed-loop signals and NN weights are uniformly ultimately bounded (UUB). Moreover, simulation results are also included to demonstrate the effectiveness of the proposed scheme.

This article deals with the extended-dissipativity-based adaptive event-triggered (AET) control problem for stochastic polynomial fuzzy singular systems (SPFSSs). The purpose of this work is to design a state-feedback controller through the AET mechanism, which not only makes the closed-loop system admissible and extended dissipative, but also saves the network resources. First, with a suitable Lyapunov–Krasovskii functional and an integral inequality in stochastic setting, an AET control criterion of SPFSSs considering asynchronous premise is established to ensure the mean-square admissibility and extended dissipativity of the closed-loop singular system. Additionally, a simple lemma is employed to approximate the nonconvex sum-of-squares (SOS) conditions with the convex SOS conditions due to the difficulty in solving the nonconvex SOS design conditions. Then, both the desired feedback controller gain and the event-triggered weighting polynomial matrix are codesigned based on the derived criterion. Finally, simulation examples are provided to illustrate the effectiveness of the proposed approaches.

Packet loss in a networked control system (NCS) is a stochastic event that depends on the current network state, which, as an abstract and hidden variable, can not be well defined but can be perceived by the observation of the packet-loss process. We model the network in an NCS as a Markov chain and the packet losses as stochastic events whose probability depends on the Markov chain state (i.e. network state). Thus, the network state estimation is a hidden Markov model (HMM) estimation problem. To derive the HMM of the NCS under study, we propose the expectation maximization (EM) algorithm to estimate the parameters of the HMM based on the packet dropping sequence. Finally, a simulation example illustrates the effectiveness of the proposed approach.

A new control mode is proposed for a networked control system whose network-induced delay is longer than a sampling period. A time-division algorithm is presented to implement the control and for the mathematical modeling of such networked control system. The infinite horizon controller is designed, which renders the networked control system mean square exponentially stable. Simulation results show the validity of the proposed theory.

We study stabilization problems for networked control systems (NCSs) with asymmetric information. In this NCSs model, the remote controller can receive packet-dropout states of the plant, and the available information for the embedded controller are observations of states and packet-dropout states sent from the remote controller. It is shown that the system is bounded in the mean-square sense if and only if there exist the solutions to the two coupled algebraic Riccati equations and the packet-dropout probability satisfies certain condition.

In this paper, a robust H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> filter for networked control system is designed. A continuous model of networked control system is investigated and it is denoted by the one that is similar to time-delay system, through some assumption and transformation. Because only limited information can be transported in the network, time-invariant logarithmic quantization is considered in the output of system. The filtering error system designed in this paper is robustly asymptotically stable and fulfils the given H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> performance level. Based on a linear matrix inequality approach, a solving method of the filter is provided. A numerical example is given to show the effectiveness of the method.