Process scheduling of laser drilling systems with collaborative positioning devices

We describe an approach for scheduling processes of laser drilling systems which can employ two positioning devices simultaneously. Note that these devices are contrastive: one is a high-speed, short-range device, while the other is a low-speed, long-range one. The objective is to minimise the machining time for each board. Despite this common objective, no publications have dealt with approaches for scheduling them so far for some reasons such as high flexibility for positioning. In our approach, we first introduce a scheme: the low-speed, long-range device moves straight with a constant speed. This scheme formulates an optimization problem which includes Asymmetric Hamiltonian Path Problem with Time Windows (AHPP-TW). We present a local search algorithm for the AHPP-TW. The algorithm is non-reversing 3-opt where lexicographic search strategy is applied. Computational experiments on real data drew a comparison between machining time with our approach and that with our conventional one. An excellent result was obtained: our approach cut machining time by 30% on average.