Optimally solving the alternative subgraphs assembly line balancing problem

Assembly line balancing problems (ALBP) consist of distributing the total workload for manufacturing any unit of the products to be assembled among the work stations along a manufacturing line as used in the automotive or the electronics industries. Usually, it is assumed that the production process is fixed, i.e., has been determined in a preceding planning step. However, this sequential planning approach is often suboptimal because the efficiency of the production process can not be evaluated definitely without knowing the distribution of work. Instead, both decisions should be taken simultaneously. This has led to the Alternative Subgraphs ALBP. We give an alternative representation of the problem, formulate an improved mixed-integer program and propose a solution approach based on SALOME, an effective branch-and-bound procedure for the well-known Simple ALBP. Computational experiments indicate that the proposed procedure is successful in finding optimal solutions for small- and medium-sized problem instances and rather good heuristic solutions for large-scaled instances.