Sampled-Data Supervisory Control

This paper focuses on issues related to implementing timed discrete-event systems (TDES) supervisors, and the concurrency and timing delay issues involved. In particular, we examine issues related to implementing TDES as sampled-data (SD) controllers. An SD controller is driven by a periodic clock and sees the system as a series of inputs and outputs. On each clock edge (tick event), it samples its inputs, changes states, and updates its outputs. We extend TDES controllability to a new definition, SD controllability, which captures several new properties that are useful in dealing with concurrency issues, as well as makes it easier to translate a TDES supervisor into an SD controller. We present controllability and nonblocking results for SD controllers. Finally, we apply our method to a small manufacturing system from the literature.