Multi-agent System for Balancing Mixed-Model Assembly Lines with Bi-objective

Due to increasing competition and differentiated demand, assembly line is no longer sufficient to offer only standardized products. To satisfy the requirement of customers with the advantages of an efficient flow line, some product variants are allowed to produce simultaneously on the same assembly line. This paper proposes a multi-agent based algorithm for a mixed-assembly line balancing problem (MALBP). The model is constructed by two-level agent architecture. In the first level, a planning agent is built to determine line cycle time based on customer demand. According to the cycle time, the ideal number of workstation is determined. In the second level, there are a balancing agent and multiple machine agents collaborating to balance the workloads of all workstations. The balancing agent records the task precedence constraints and the workload of each workstation, and calculates the efficiency of line balancing. Tabu search algorithm is applied as a communication mechanism between machine agents to adjust the workloads of all workstations. The primary objective is to minimize the number of workstation for a given cycle time, and secondary objective is to minimize the variance of the workload of workstations. In this paper, a workstation is viewed as an agent. Adjacent swap and insert mechanism is applied to search the neighborhood, and, furthermore, tabu list is used to avoid the solution trapped into local optimal.