In the context of networked discrete-event systems (DESs), communication delays and losses exist between the plant and the supervisor for observation and between the supervisor and the actuator for control. In this paper, we first introduce a new framework for supervisory control of networked DESs. Under the introduced framework, we address the state estimation problem for supervisor synthesis of networked DESs with both communication delays and losses. The estimation algorithm considers the effect of the controls imposed on the system. Additionally, the estimation algorithm is based on the control decisions available up to the moment, and all the future control decisions are assumed to be unknowable. Two notions, called "observation channel configuration" for tracking observation delays and losses and "control channel configuration" for tracking control delays and losses, are defined. Then, we introduce an online approach for state estimation of the controlled system. Compared with the existing approach, the proposed approach under the introduced framework can estimate the state of the controlled system more accurately. As an application of the proposed approach, we finally show that the existing methods can be easily applied to synthesize maximally permissible and safe networked supervisors.
In this work, we study the problem of supervisory control of networked discrete event systems. We consider lossy communication channels with bounded network delays, for both the control channel and the observation channel. By a model transformation, we transform the networked supervisor synthesis problem into the classical (non-networked) supervisor synthesis problem (for non-deterministic plants), such that the existing supervisor synthesis tools can be used for synthesizing networked supervisors. In particular, we can use the (state-based) normality property for the synthesis of the supremal…
Conventional supervisory control theory assumes full synchronization between the supervisor and the plant. This assumption is violated in a networked-based communication setting due to the presence of delays, and this may result in incorrect behavior of a supervisor obtained from conventional supervisory control theory. This paper presents a technique to synthesize a networked supervisor handling communication delays. For this purpose, first, a networked supervisory control framework is provided, where the supervisor interacts with the plant through control and observation channels, both of wh…
This paper presents an overview of the networked supervisory control framework for discrete event systems with imperfect communication networks, which can be divided into the centralized supervisory control setup and the decentralized supervisory control setup. We review the state-of-art networked control frameworks with observation channel delays and control channel delays, for untimed and timed models. Data losses in communication channels are also considered. The review of the state-of-art networked control frameworks will be focused on the following parts: 1) the construction of the networ…
Supervisor Localization of Timed Discrete-Event Systems under Partial Observation and Communication Delay
School of Automation, Northwestern Polytechnical University（西北工业大学自动化学院）；Department of Electrical and Information Engineering, Osaka City University（大阪城市大学电气与信息工程学院）
In decentralized networked supervisory control of discrete-event systems (DESs), the local supervisors observe event occurrences subject to observation delays to make correct control decisions. Delay coobservability describes whether these local supervisors can make sufficient observations. In this paper, we provide an efficient way to verify delay coobservability. For each controllable event, we partition the specification language into a finite number of sets such that strings in different sets have different lengths. For each of the sets, we construct a verifier to check if delay coobservab…
Delay-Robustness in Distributed Control of Timed Discrete-Event Systems Based on Supervisor Localization
School of Automation, Northwestern Polytechnical University（西北工业大学自动化学院）；Urban Research Plaza, Osaka City University（大阪市立大学城市研究广场）；School of Electrical Engineering, Xi¡¯an Jiaotong University（西安交通大学电气工程学院）；Systems Control Group, Department of Electrical and Computer Engineering, University of Toronto（多伦多大学电气与计算机工程系系统控制组）
Distributed Supervisory Control of Discrete-Event Systems with Communication Delay
School of Automation, Northwestern Polytechnical University（西北工业大学自动化学院）；Urban Research Plaza, Osaka City University（大阪市立大学城市研究广场）；School of Electrical Engineering, Xi¡¯an Jiaotong University（西安交通大学电气工程学院）；Systems Control Group, Department of Electrical and Computer Engineering, University of Toronto（多伦多大学电气与计算机工程系系统控制组）
In this paper, we propose a novel framework for modeling and analysis of networked discrete-event systems (DES). We assume that the plant is controlled by a feedback supervisor whose control decisions are subject to communication delays and losses. Furthermore, we consider a general setting where the supervisor sends control decisions to different actuators via different communication channels whose dynamics are independent. We provide a system theoretic approach by identifying the state-space of overall networked system and investigating the dynamic of the entire state-space. Our approach pre…
An analytical framework for analysis and design of networked control systems with random delays and packet losses
National Institute of Technology- Calicut（卡利卡特国家理工学院）；ABB India Corporate Research Center（ABB印度企业研究中心）；National Institute of Technology-Tiruchirappalli（蒂鲁奇拉帕利国家理工学院）
In this paper, we investigate both qualitative and quantitative synthesis of optimal privacy-enforcing supervisors for partially-observed discrete-event systems. We consider a dynamic system whose information-flow is partially available to an intruder, which is modeled as a passive observer. We assume that the system has a "secret" that does not want to be revealed to the intruder. Our goal is to synthesize a supervisor that controls the system in a least-restrictive manner such that the closed-loop system meets the privacy requirement. For the qualitative case, we adopt the notion of infinite…
In this paper, we investigate the covert sensor attack synthesis problem in the framework of supervisory control of networked discrete-event systems (DES), where the observation channel and the control channel are assumed to be non-FIFO and have bounded network delays. We focus on the class of sensor attacks satisfying the following properties: 1) the attacker might not have the same observation capability as the networked supervisor; 2) the attacker aims to remain covert, i.e., hide its presence against the networked monitor; 3) the attacker could insert, delete, or replace compromised observ…
The communication channels used to convey information between the components of wireless networked control systems (WNCSs) are subject to packet losses due to time-varying fading and interference. The WNCSs with missing packets can be modeled as Markov jump linear systems with one time-step delayed mode observations. While the problem of the optimal linear quadratic regulation for such systems has been already solved, we derive the necessary and sufficient conditions for stabilizability. We also show, with an example considering a communication channel model based on WirelessHART (a on-the-mar…
The communication channels used to convey information between the components of wireless networked control systems (WNCSs) are subject to packet losses due to time-varying fading and interference. We consider a wireless networked control scenario, where the packet loss occurs in both the sensor-controller link (sensing link) and the controller-actuator link (actuation link). Moreover, we consider one time-step delay mode observations of the actuation link. While the problems of state feedback optimal control and stabilizability conditions for systems with one time-step delay mode observations …
A Passivity-Based Design for Stability and Robustness in Event-Triggered Networked Control Systems with Communication Delays, Signal Quantizations and Packet Dropouts
