HUMAN REACH POSTURE PREDICTION BASED ON PSYCHOPHYSICAL DISCOMFORT

A man model is a useful design tool for the evaluation of man- machine systems and products with less time delay and cost, specifically at t he early stage of design. For a man model to be truly useful, it must be integrated with a proper posture prediction model, especially, an a rm reach prediction model. In this study, a regression model to predic t the: perceived discomfort with respect to the joint movement was dev eloped using a central composite design based on the response surface method. Joint angles of the upper body with seven degrees of freedom a nd the weight of a load were treated as independent variables while th e perceived discomfort measured using a magnitude estimation technique was used for the response variable. The perceived discomfort in the c ategory scale and the normalized EMG of six muscles were also collecte d, A three-dimensional reach posture prediction model using an inverse kinematics technique was then developed, based on the prediction of p erceived discomfort. The model predicts the posture by selecting the m inimum discomfort configuration among feasible body postures to reach a target point. The reach posture prediction model developed in this s tudy was found to simulate human arm reach posture accurately and the discomfort prediction model will help understand the human arm reach m ovement.