Supervisory control using failure semantics and partial specifications

A framework is presented for the supervisory control of nondeterministic discrete-event systems based on failure semantics. It guarantees deadlock-free behavior under all circumstances, it allows for powerful specifications, it forms a sound basis for modular control, and it can handle nondeterminism without extra effort. A synthesis method to generate the least restrictive supervisor is presented. The control problem with partial specification is formulated, and it is shown that this control problem can be rewritten to a control problem with full specification. Special care has to be taken for traces with an unbounded internal extension (divergence). A condition, denoted bounded recurrence, is introduced to handle these traces. It is shown that the external behavior of the controlled system is not restricted by this condition