Simulation for sagittal plane lifting activities

Abstract

Biomechanics provide estimation of various mechanical stresses acting on the body while a person manually handles an object. Although motion analysis systems are available for dynamic biomechanical analyses, uses of such systems are mostly performed in laboratory due to high cost of the equipment and the expertise required in using them. Industrial ergonomists have limited access to dynamic biomechanical analyses. This paper reports a dynamic simulation model developed for biomechanical analyses of sagittal lifting activities. The model simulates the dynamic motion of lifting tasks for five body joints: the elbow, shoulder, hip, knee, and ankle. The inputs of the model include initial and final joint postures; gender, weight, and height; weight of load; lifting height; and container dimensions. The output provides the angular trajectories of the five joints. The model without any video inputs predicts the motion patterns of the lift. Actual motion data were collected using 10 subjects in the laboratory for 360 lifts which included 12 lifting tasks in combination of two lifting heights, two container sizes, and three weights of load. Good results were obtained from the dynamic planar motion simulation model. The predicted motion patterns from the simulation closely resemble the observed motion pattern.