Résolution d'un problème d'ordonnancement avec la PLC

Electroplating facilities consist in a line of tanks in which products must be successively emerged. A set of hoists ensures the transport of pieces from a tank to another one, without allowed pauses. The control of such hoists generates a scheduling problem known as the Hoist Scheduling Problem in the literature. To maximize the productivity of the lines a sequence of hoist movements has to be found. This article presents a model that is able to provide the optimal n-cyclic schedule for the mono-product case. The implementation of this model is based on the Constraint Logic Programming concepts. This approach ensures an easy extension of the basic model. In particular, the multi-hoist case has been easily developed with this tool. The paper shows how the Constraint Logic Programming tools fill the gap of Operational Research approaches, and give some computational results for a benchmark and some real-life examples.