Multi-objective optimization of the multi-floor facility layout problem

The multi-floor facility layout problem (MFLP) involves the optimal arrangement of given facilities in multiple floors. Considering that the facilities are to be arranged in multiple floors starting from the left origin of each floor, the MFLP is formulated here as a multi-objective optimization problem for simultaneously minimizing the number of floors and the overall material handling cost. The overall material handling cost involves the individual material handling cost among the facilities arranged in the same floor as well as in different floors. The horizontal and vertical material handling costs between two given facilities are considered to be different as the vertical flow of materials requires the install of elevators also. Solving the present formulation of the MFLP by customizing a permutation-based genetic algorithm, results of a number of test instances of varying sizes are provided as benchmark.