Template-Based Controller Synthesis for Timed Systems

We present an effective controller synthesis method for realtime systems modeled as timed automata with safety requirements. Under the realistic assumption of partial observability, the problem is undecidable in general, and prohibitively expensive (2ExpTime-complete) if a bound on the granularity of the controller is set in advance. We investigate the synthesis of controllers from templates, given as timed automata with parametric control structure. Template-based synthesis is significantly cheaper (PSpace-complete) than standard synthesis and produces much simpler controllers. We present an efficient symbolic synthesis algorithm based on automatic abstraction refinement and report on encouraging experimental results from an implementation in the timed verification and synthesis tool Synthia.