Production Scheduling by Reachability Analysis - A Case Study

Schedule synthesis based on reachability analysis of timed automata has received attention in the last few years. The main strength of this approach is that the expressiveness of timed automata allows -- unlike many classical approaches -- the modelling of scheduling problems of very different kinds. Furthermore, the models are robust against changes in the parameter setting and against changes in the problem specification. This paper presents a case study that was provided by Axxom, an industrial partner of the Ametist project. It consists of a scheduling problem for lacquer production, and is treated with the timed automata approach. A number of problems have to be addressed for the modelling task: the information transfer from the industrial partner, the derivation of timed automaton model for the case study, and the heuristics that have to be added in order to reduce the search space. We try to isolate the generic problems of modelling for model checking, and suggest solutions that are also applicable for other scheduling cases. Model checking experiments indicate that -- for this problem -- the timed automata approach is competitive with Axxom's planning tool