Discrete-Time Control for Rectangular Hybrid Automata

Thomas A. Henzinger and Peter W. Kopke

Rectangular hybrid automata model digital control programs of analog plant environments. We study rectangular hybrid automata where the plant state evolves continuously in real-numbered time, and the controller samples the plant state and changes the control state discretely, only at the integer points in time. We prove that rectangular hybrid automata have finite bisimilarity quotients when all control transitions happen at integer times, even if the constraints on the derivatives of the variables vary between control states. This is in contrast with the conventional model where control transitions may happen at any real time, and already the reachability problem is undecidable. Based on the finite bisimilarity quotients, we give an exponential algorithm for the symbolic sampling-controller synthesis of rectangular automata. We show our algorithm to be optimal by proving the problem to be EXPTIME-hard. We also show that rectangular automata form a maximal class of systems for which the sampling-controller synthesis problem can be solved algorithmically.

Theoretical Computer Science 221:369-392, 1999. A preliminary version appeared in the Proceedings of the 24th International Colloquium on Automata, Languages, and Programming (ICALP), Lecture Notes in Computer Science 1256, Springer, 1997, pp. 582-593.

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