Computer motion simulation for sagittal plane lifting activities

In ergonomics, the biomechanical approach provides estimation of various me chanical stresses acting on the body while a person manually handles an obj ect. Although motion analysis systems are available for dynamic biomechanic al analyses, the use of such systems are mostly performed in laboratory due to high cost of the equipment and the expertise required in using them. In dustrial ergonomists have limited access to dynamic biomechanical analyses. This paper reports a dynamic simulation model developed for biomechanical analyses of lifting activities performed in the sagittal plane. The model s imulates the dynamic motion of lifting tasks for five body joints: the elbo w, shoulder, hip, knee, and ankle. The inputs of the model include initial and final joint postures; gender, weight, and height; weight of load; lifti ng height; and container dimensions. In the output, the angular trajectorie s of the five joints are predicted. The model without any video inputs pred icts the motion patterns of the lift. Actual motion data were collected usi ng 10 subjects in the laboratory for 360 lifts which included 12 lifting ta sks in combination of two lifting heights, two container sizes, and three w eights of load. Good results were found for the dynamic planar motion simul ation model. The predicted motion pattern from the simulation closely resem bles the observed motion pattern.