Showing papers by "W. M. Wonham published in 2001"

Hierarchical interface-based supervisory control: serial case

Abstract: We present a hierarchical method that decomposes a system into two subsystems, and restricts the interaction of the subsystems by means of an interface. We present a definition for an interface, and define a set of interface consistency properties that can be used to verify if a discrete-event system is nonblocking and controllable. Each clause of the definition can be verified using only one of the two subsystems; thus the complete system model never needs to be constructed, offering significant savings in computational effort. Additionally, the development of clean interfaces facilitates re-use of the component subsystems.

Stable supervisory control of flexible manufacturing systems with fixed supply and demand rates

Abstract: In this article, we develop a method for computing a stable supervisory control for a class of manufacturing systems (consisting of reconfigurable processors and buffers with limited capacities) with fixed supply and demand rates. It is shown that, with this method, we are able to (i) decide constructively whether a stable supervisory control exists for a given manufacturing system, and (ii) compute the stable supervisory control if it exists. Furthermore, the stable supervisory control thus obtained is complete in the sense that it contains all 'safe' sequences (of possibly concurrent buffer and processor activities) which guarantee the stability of the system. An example is presented to illustrate the proposed method. Implications and computational complexity associated with this method are discussed.