Examination on lifting motion with different start-on posture, and study on the proper opration using minimum jerk model

The aim of this research is to establish the quantitative evaluation method for lifting task and to clarify the safety posture and optimal motion. This paper firstly examines the operation from differenet three start-on postures with four items: the maximum compressive force and share force on L5/S1 joint, the energy efficiency index, and the degree of contribution of each joint. As a result it has been shown that the load not only to lumbar vertebra but to knee joint should be emphasized and the pose-C is an appropriate start on posture in which the knee is flexed almost at right-angled and the upper body is raised. Moreover from the simulation using minimum jerk model we found a proper operation, but the actual operation has earlier timing to extend the lower body than presumed. So not only the criteria on the whole operation or the relative criteria but also the absolute criteria paying attention to a portion like knee joint moment seems necessary to study the optimal lifting motion.