Optimizing ergonomics in assembly lines: A multi objective genetic algorithm

Ergonomics is an essential aspect to deal with while solving problems related to manual assembly, for the effects it may have on both productivity and human factor related issues. The frequent execution of repetitive movements and the handling of heavy components are among the main factors that characterize the assembly process, potentially resulting in worker's overload. An appropriate distribution of assembly operations and, therefore of relative workloads, on a production line can improve ergonomic aspects, according to the worker's anthropometric and physiological characteristics. In this paper, a multi-objective genetic algorithm for solving the assembly line balancing problem taking into account ergonomics based on energy expenditure is proposed. The novelty of the contribution relies in the assignment of assembly tasks to workstations considering a set of human operators actually available in a company. The assignment of workers is based on their physical capabilities and limits, evaluated according to their anthropometric and physiological characteristics. The objectives of the problem, besides the minimization of the number of workstations, are related to the human factor; in particular, the distribution of assembly tasks to workstations according to worker technical skills and to worker physical capabilities are optimized. A practical case study taken from the industrial reality is finally tested and discussed.