Controlled timed automata

We examine some extensions of the basic model, due to Alur and Dill, of real-time automata (RTA). Our model, controlled real-time automata, is a parameterized family of real-time automata with some additional features like clock stopping, variable clock velocities and periodic tests. We illustrate the power of controlled automata by presenting some languages that can be recognized deterministically by such automata, but cannot be recognized non-deterministically by any other previously introduced class of timed automata (even with ɛ-transitions). On the other hand, due to carefully chosen restrictions, controlled automata conserve basic properties of RTA: the emptiness problem is decidable and for each fixed parameter the family of recognized real-time languages is closed under boolean operations.