Machine-fixture-pallet resources constrained flexible job shop scheduling considering loading and unloading times under pallet automation system

Pallet automation system (PAS) has gained more and more attention from many manufacturing enterprises with the development of flexible automation, where machine, fixture, and pallet are three critical resources. Few scholars study flexible job shop scheduling considering fixture and pallet resources. Meanwhile, they ignore the loading and unloading times, potentially leading to an extended makespan. Therefore, this paper presents a novel machine-fixture-pallet resources constrained flexible job shop scheduling problem considering loading and unloading times under a pallet automation system (FJSP-PAS). A mixed-integer programming model is established to minimize makespan. Considering the mutual constraints among resources, a new decoding method to choose resources for minimizing delay time (MDT) is proposed. An improved adaptive large neighborhood search algorithm (IALNS) with the simulated annealing method for local search is applied. The case study illustrates that IALNS with MDT rule for decoding (IALNS-MDT) can effectively reduce makespan while MDT enhances the quality of initial solutions. Furthermore, the importance of fixture-pallet resource allocation is emphasized by a given example, which inspires enterprises to make better resource allocation decisions.