Ahmad W. Al-Dabbagh

Design Considerations for Wireless Networked Control Systems

In traditional networked control systems, wired communication networks are used for the transmission of information between the communicating systems. With the increasing demand for distributed systems and the growth in the scale of the applications, the use of wireless communication networks offers significant advantages over their wired counterparts. To facilitate the deployment of a fully automated closed-loop wireless networked control system (WNCS), this paper addresses several design considerations for a proposed topology for potential use as a closed-loop WNCS. The topology consists of a plant system having sensor and actuator nodes, a controller system having input and output nodes, an intermediate network system having interconnected nodes, and wireless communication links for the information transfer between the different nodes of the plant, controller, and network systems. More specifically, the design considerations addressed in the paper are: the condition requirements needed to facilitate the design of optimal controller and network systems, the joint design of optimal controller and network systems to control the plant system, and the structured model reduction of the closed-loop WNCS to reduce its scale. Finally, simulation examples are provided to demonstrate the applicability of discussed design considerations.

Modelling and control of wireless networked control systems: A fixed structure approach

This paper proposes a system topology for potential use as a Wireless Networked Control System (WNCS). The topology has a plant to be regulated, a dedicated controller that makes control decisions, and an intermediate network of nodes. The network assists the controller in stabilizing the closed-loop system and provides the means for connecting the sensors and actuators of the plant and the inputs and outputs of the controller. Further, the paper presents a framework for modelling the closed-loop system such that controller and network systems can be designed. The paper also provides an LMI-based algorithm for computing optimal controller and network systems that achieve a stable closed-loop system while meeting performance measures. The deigned systems have a fixed structure and hence the associated design complexity is reduced. Finally, the paper also illustrates with examples the effectiveness of the proposed design and computational procedures.

An Intrusion Detection System for Cyber Attacks in Wireless Networked Control Systems

In this brief, a proposed topology for a wireless networked control system is studied under several cyber attack scenarios, and a distributed intrusion detection system (IDS) is designed to identify the existence of attacks. More specifically, this brief presents a modelling framework for the closed-loop control system with the IDS and a computational procedure to design and compute the IDS. The computational procedure delivers a stable closed-loop control system with the IDS being sensitive to cyber attacks. Also, a simulation example is used to illustrate the application of the proposed procedure as well as its effectiveness.

A fixed structure topology for wireless networked control systems

This paper presents the formulation, modelling and design of a fixed structure topology for potential application in wireless networked control systems. The topology consists of a standard plant system, an output feedback controller system, and intermediate transfer and receiving network systems. The paper defines the topology and addresses the modelling of the closed-loop control system. It presents a modelling framework to design the controller, the transfer network, and the receiving network systems. Also, the paper discusses a design procedure of using shared network systems for a closed-loop control system with multiple plant and controller systems. The design procedures utilize LMI-based algorithms and deliver an internally stable closed-loop control system whose inputs and outputs satisfy an ℓ2 - ℓ∞ performance criterion. The practicality of the design procedures is demonstrated using an illustrative example.