Simultaneous balancing and scheduling of flexible mixed model assembly lines

The primary aim of this PhD study is to introduce new model formulations and solution approaches for flexible mixed model assembly lines (FMMAL), which deal with simultaneous balancing and scheduling problems (SBSFMMAL) with sequence dependent issues and parallel stations in a cyclic manner. In this PhD study, first, a mixed integer programming (MIP) formulation is developed to model and solve SBSFMMAL problem. Next, various decomposition schemes are applied to the proposed MIP model to solve large-size problem instances. Following, based on the insight gained from the MIP model and decompoisition schemes, a constraint programming model (CP) is developed to solve the problem. Possible hybridization schemes to combine MIP, decomposition and CP methods are proposed. Lastly, some search heuristics and symmetry breaking constraints are suggested to improve the performance of the constraint programming models. The steps summarized above are applied to all extensions of the SBSFMMAL problem including sequence dependent task time increments (SBSFMMAL-SDTI), sequence dependent setup times (SBSFMMAL-SDST), cyclic scheduling (SBSFMMAL-Cyclic), and parallel stations (SBSFMMAL-PS) where proposed methods are comparatively evaluated on various size instances. Keywords : Mixed model assembly lines, flexible manufacturing, balancing, sequencing, cyclic scheduling, mixed integer programming, constraint programming, decomposition