Abstract
The aim of the present study was to formulate the relationship between the total perceived discomfort (TPD) and six joint moment ratios of the entire body (i.e., shoulder, elbow, L5/S1, hip, knee, and ankle joint moment ratios). A manual material handling experiment was performed. Twelve healthy Japanese subjects (six males and six females), aged between 21 and 24, participated in this experiment. The subjects were required to hold a weight with varying holding point and load amplitude, and joint angles and subjective TPD were measured. In addition, the joint moment ratios were calculated from the measured joint angles. Three approximation models (i.e., sum, maximum, and square sum) were compared in terms of the accuracy of predicting the TPD, and the sum model was selected because its average error was lowest. The correlation coefficient between measured and predicted TPD of the function was compared to that of four observational methods (i.e., OWAS, RULA, REBA, and NIOSH lifting equation). The correlation ratio was highest for the proposed TPD function followed by REBA.
