Robust decentralized supervisory control of discrete-event systems

In this thesis we study robust supervisory control of discrete event systems in two different settings. First, we consider the problem of synthesizing a set of decentralized supervisors when the precise model of the plant is not known, but it is known that it is among a finite set of plant models. To tackle this problem, we form the union of all possible behaviors and construct an appropriate specification, from the given set of specifications, and solve the conventional decentralized supervisory control associated with it. We also prove that the given robust problem has a solution if and only if this conventional decentralized supervisory control problem has a solution. In another setting, we investigate the problem of synthesizing a set of communicating supervisors in the presence of delay in communication channels, and call it Unbounded Communication Delay Robust Supervisory Control problem (UCDR-SC problem). In this problem, We assume that delay is unbounded but it is finite, meaning that any message sent from a local supervisor will be received by any other local supervisors after a finite but unknown delay. To solve this problem, we redefine the supervisory decision making rules, introduce a new language property called unbounded-communication-delay-robust (UCDR), and present a set of conditions on the specification of the problem. We also show that the new class of languages that is the solution to this problem has some interesting relations with other observational languages