Holistic Cyber-Physical Management for Dependable Wireless Control Systems

Abstract

Wireless sensor-actuator networks (WSANs) are gaining momentum in industrial process automation as a communication infrastructure for lowering deployment and maintenance costs. In traditional wireless control systems the plant controller and the network manager operate in isolation, which ignore the signi cant in uence of network reliability on plant control performance. To enhance the dependability of industrial wireless control, we propose a holistic cyber-physical management framework that employs run-time coordination between the plant control and network management. Our design includes a holistic controller that generates actuation signals to physical plants and recon gures the WSAN to maintain desired control performance while saving wireless resources. As a concrete example of holistic control, we design a holistic manager that dynamically recon gures the number of transmissions in the WSAN based on online observations of physical and cyber variables. We have implemented the holistic management framework in the Wireless Cyber-Physical Simulator (WCPS). A systematic case study has been presented based on two 5-state plants sharing a 16-node WSAN. Simulation results show that the holistic management design has signi cantly enhanced the resilience of the system against both wireless interferences and physical disturbances, while e ectively reducing the number of wireless transmissions. With the adoption of industrial wireless standards such asWirelessHART [15] and ISA100 [37], wireless sensoractuator networks (WSANs) are being deployed in process industries world wide. However, existing WSAN in process industries are usually used for monitoring applications. ere remain signi cant challenges in supporting feedback control systems over WSAN due to concerns about dependability of wireless control systems (WCS). A wireless control system (WCS) employs a WSAN as the communication infrastructure for one or more feedback control loops, where the sensors, controllers and actuators communicate over the WSAN. Despite considerable e orts to enhance the reliability of industrial WSAN, data loss is inevitable in open and hash operating environments, which may lead to severe degradation of control performance, or even system instabilities. A dependable WCS therefore must maintain system stability and acceptable control performance under both physical disturbance and wireless interference. A WCS is particularly vulnerable when signi cant data loss coincides with the plant experiencing a poor physical state. eFig. 1. Traditional design (le ) vs. holistic co-design (right) of wireless process control systems. challenge to utilize the WSAN for feedback control prevents the process industries from exploiting the full potential of wireless technologies, forcing plants to maintain extensive wired infrastructure despite the existence of the WSAN. erefore, it is critical to develop WCS that are dependable under challenging cyber and physical conditions. Although the control system performance is heavily in uenced by WSAN reliabilit...

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