Hybrid Flow Shop Multi Objective Scheduling with Sequence Dependent Setup Times and Machine Availability Constraints
The hybrid flow shop environment is one of the most common species of flow shop used in many industries including automotive, chemical industries, textile, etc. In this research we contemporaneously investigate scheduling of this environment and the Preventive Maintenance together. As in the real world the utilities and interests of customer and producers are different and even opposite in many cases, the necessity of production scheduling with multi objectives will become more obvious. In this paper we try to investigate the Hybrid flow shop scheduling with the assumption of setup times related to sequence and limited availability of machines, in order to minimize the completion time and total tardiness times of jobs. The studied problem is a combinatorial optimization problem which its complicated nature makes it impossible to be solved in the natural time. Therefore, we try to find a suitable meta heuristic algorithm, for solving the problem. In this research we suggest two algorithms named MO VNS and MO GA VNS that both of them are multi objective methods based on Pareto Archive. Numerical examples are used to evaluate presented algorithms. We perform some experiments for evaluating the suggested methods. Due to these experiments some sample problems are designed and generated. The results show that MO GAVNS algorithm is much better comparing the other algorithms.