Multi-objective optimisation method for posture prediction and analysis with consideration of fatigue effect and its application case

Automation techniques have been widely used in the manufacturing industry, but there are still many manual handling operations required in assembly and maintenance work. Inappropriate posture and physical fatigue might result in musculoskeletal disorders (MSDs) in such physical jobs. In ergonomics and occupational biomechanics, virtual human modelling techniques have been employed to optimize manual operations in the design stage so as to avoid or decrease risk of MSD. In these methods, physical fatigue is only considered to minimize muscle or joint stress, while the effect of fatigue along time on posture is not often considered, although worker’s motion strategies and postures under physical fatigue are different from those under non-fatigue conditions. In this paper, based on related literatures and multiple-objective optimisation method (MOO), a new posture prediction and analysis method is proposed for predicting the optimal posture under non-fatigue and fatigue conditions and evaluating the physical fatigue in manual material handling operation. The posture prediction and analysis problem is mathematically described, and a special application case is demonstrated for analyzing a drilling assembly operation in European Aeronautic Defence and Space Company (EADS).