A Constraint Programming Model for a Reconfigurable Job Shop Scheduling Problem with Machine Availability.

A reconfigurable manufacturing system (RMS) is one of the attractive production paradigms that has emerged to face the challenges in the market. Moreover, in a real production system, machines may be out of reach because of various reasons, such as inspection, periodic maintenance, and sudden breakdown. Implementing a proper schedule in this environment can have a significant impact on the growth and success of manufacturing companies. In this regard, this paper deals with scheduling in a reconfigurable job shop environment consisting of flexible maintenance operations. To this aim, a mixed-integer linear programming (MILP) model is presented to minimize the makespan. Regarding the high complexity of the problem and the industrial need of having good solutions in a short time, a constraint programming (CP) model is developed as well. Then, a computational experiment and sensitivity analysis are conducted. The presented models are assessed by solving a series of test problems. It is concluded that the proposed CP model significantly outperforms the MILP model for large-sized instances.