Balancing time and physical effort in two-sided assembly lines

In assembly line balancing problems, time is balanced among workers. This does not necessarily balance their physical effort. The effort exerted by workers varies depending on the type of the job, and the size and weight of the component. In the two-sided assembly lines, commonly used for heavy industries, the variation in physical effort among workers is more emphasized. The unbalanced effort leads to fatigue, and may lower productivity and quality. This work aims at balancing the physical effort among workers in the two-sided assembly lines, while considering other conventional objectives. A genetic algorithm and a new decoding scheme are proposed. An effort smoothness index (ESI) is introduced to measure the variation in effort among workers. Results prove that balancing the physical effort is influential and can be achieved at no extra cost for most cases. Effort balancing is harder to achieve in difficult problems; of high order of strength