Wirelessly Enabled Control of Cyber-Physical Infrastructure with Applications to Hydronic Systems.

Abstract

Civil infrastructure systems, such as transportation networks, pipe networks, electrical grids, and building environments, are typically managed and controlled with outdated, inefficient, and minimally automated legacy controllers. This is apparent from documented oil pipeline leaks, broad electrical outages, and power plant failures. The relatively recent advents of small inexpensive microcontrollers and low-power wireless networking technologies has revealed opportunities for better managing the operational effectiveness of civil infrastructure systems. Academic research in this field is maturing, yet the field remains in its nascent years of commercial viability, focusing mainly on low data-rate sensing with centralized processing. Little focus has been on distributed wireless control systems for civil infrastructure.

This dissertation follows the development and utilization of a new cyber-physical system (CPS) architecture for civil infrastructure. Embedded computing power is distributed throughout the physical systems and global objectives are met with the aid of wireless information exchange. The Martlet wireless controller node was conceived during the first part of this thesis to enable this objective of wirelessly distributed CPS. Once produced, the Martlet was used to realize such a controller, motivated by an application in hydronic cooling systems.

The design of the proposed controller began with a study concerning models and objective functions for the control of bilinear systems, like those found in hydronics, when constrained by the resources of a wireless control node. The results showed that previous work with linear quadratic controllers could be improved by using nonlinear models and explicit objective functions. An agent-based controller utilizing the proposed bilinear model-predictive control algorithm, was then developed accounting for the limitation of, and leveraging the advantages of, wireless control nodes in order to regulate a hydronic system with hybrid dynamics. The resulting Martlet based control system was compared to traditional benchmark controllers and shown to achieve adequate performance, with the added benefits of a wireless CPS.

These developments in wirelessly distributed control of complex systems are presented not only with the tested hydronic systems in mind, but with the goal of extending this technology to improve the performance and reliability of a wide variety of controlled cyber-physical civil infrastructure systems.