Abstract
This paper formulates an optimal control model that reproduces human whole-body reaching movements with cooperation between arm and body. The model consists of four links (an arm, an upper body, a thigh, and a lower leg) and four joints (shoulder, hip, knee, and ankle joints), and minimizes the sum of square of torque-change integrated over the movement duration. This paper applies the proposed model to reproducing whole-body movements with cooperation between rising and reaching movements, and clarifies its performance and factors indispensable in reproducing the same whole-body movements as humans. Consequently, the following results are shown: (1) the input weight R_<44> of the model's shoulder joint affects the way of cooperation between the model's arm and body in the optimally-predicted whole-body reaching movements; (2) smaller (or larger) values of R_<44> expand (or narrow) the range of swing back of the model's arm in the optimally-predicted movements; (3) the optimal movement predicted at a large value of R_<44> agrees well with the experimental one; (4) a decrease in the input weight of R_<44> causes a decrease in the magnitude of the model's hip-joint torque. These results suggest that the proposed model is effective in simulating whole-body reaching movements with cooperation between arm and body and that the input weight R_<44> can be a factor involved strongly in the way of cooperation between arm and body.
