Multitasking Supervisory Control of Discrete-Event Systems

Abstract

This paper presents an approach for functionally dealing with multiple tasks in the supervisory control of discrete-event systems (DES). The colored marking generator (CMG), a special type of Moore automaton, is introduced as a model that distinguishes classes of tasks in DES. The main results of supervisory control theory are extended to this model, allowing the synthesis of minimally restrictive supervisors, which respect the safety specifications and ensure coreachability of multiple control objectives. Reversibility is also investigated as an alternative way of ensuring liveness of multiple tasks. Two examples illustrate the convenience of this approach.

Learning Assumptions for CompositionalVerification of Timed Systems

“…A flexible manufacturing system (FMS) [33] produces blocks with a cylindrical painted pin from raw blocks and raw pegs. It consists of fourteen devices: three conveyors, two mills, a lathe, a painting device, six robots, and an assembly machine.…”

Yet another approach to compositional synthesis of discrete event systems

“…In this section, the proposed synthesis procedure is applied to a part of the "Flexible Manufacturing System" (FMS) [18]. The model consists of a robot R, a conveyor C , a painting device PD , an assembly machine AM , and two buffers B 7 and B 8 .…”

Generalised nonblocking

“…In this example, a single nonblocking check is not enough to verify the liveness requirements of a system. The possibility of handling multiple termination conditions simultaneously and its use in synthesis is discussed in [14].…”

“…The concept is similar to that of Kripkestructures [19], but the above definition is inspired by [14]. The main difference to [14] is the colouring map Ξ, which maps propositions to state sets and not vice versa, to allow for slightly more concise notation in this paper.…”

“…To overcome some of the weaknesses, nonblocking has been generalised to handle multiple marking conditions [13], [14]. During their attempts to develop compositional verification methods for the conditions of hierarchical interface-based supervisory control [15], the authors discovered a nonblocking-like verification problem that still is difficult to cast into standard nonblocking.…”