Supervisory control of concurrent discrete-event systems

When a discrele-event system P consists of several subsystems P₁,...,P_n which operate concurrently, a natural approach to the supervisory control problem is to synthesize a ‘local’ controller S_i , for each subsystem P_i , and operate the individually controlled subsystems S_i/P_i concurrently. Such an approach is called concurrent supervisory control and is closely related to decentralized supervisory control as studied by Cieslak et al. (1988) and Lin and Wonham (1988). In the present paper simple and easily computable conditions are developed which guarantee that concurrent supervisory control can achieve the optimal behaviour achievable by a global supervisor. To achieve this, two specific concurrent control strategies are introduced.