| The integration of computers, communication, and control in modern distributed systems such as intelligent transit systems and industrial facilities has garnered a great deal of attention in recent years. This thesis presents an investigation into basic research, technology development, and implementation of monitoring and control strategies for networked-enabled dynamical systems. In view of the hierarchical nature of these systems, the thesis focuses on two important system layers; namely, networked control systems within the direct-control (servo) layer, and remote monitoring and supervisory control within the supervisory-layer.; In the present work, a networked control system (NCS) comprises the traditional components of a control system such as a plant, sensors, actuators, controllers, and signal conditioning and modification devices, but may be geographically distributed and linked through a communication network. In particular, in an NCS, the traditional feedback control loops are closed through a real-time communication network. A primary objective of the present thesis is to investigate, analyze, develop, implement and test stable control strategies to overcome the transmission problems between sensors, actuators, and controllers in an NCS; specifically, non-deterministic delay, losses, vacant sampling, and mis-synchronization of data/information. The term networked control is used in this thesis to mean the control of a networked system, and a networked system with a controller as an integral part is an NCS.; In this thesis, a new networked control strategy is developed which takes advantage of the potential capability of constrained Model Predictive Control (MPC) to compensate for anticipated data transmission problems. The constructive and computationally inexpensive strategy, which is developed here, uses predictions of future control actions and estimations of possibly erroneous sensory signals, to maintain good performance and stability of a closed-loop NCS, through an innovative method of information buffering.; The analytical issues of system stability of the new networked control strategy are rigorously treated in the thesis. The analysis is carried out in two stages. In the first stage, prefect state measurement is assumed to develop the necessary and sufficient conditions for guaranteeing closed-loop asymptotic stability while utilizing predicted future control actions that are suboptimal. The second stage of stability analysis assumes imperfect state measurement with the purpose of determining the amount of deviation between the actual states and the estimated states that can be sustained in stable manner by the developed networked control strategy. (Abstract shortened by UMI.)... |
