A DYNAMIC MODEL OF BODY SWAY CONTROL DURING UPRIGHT STANCE IN HUMAN / 体力科学

ABSTRACT

The aim of this study is to establish a new dynamic model for balance keeping control in upright standing; and to deduce the underlying possible control mechanism of central neuronal system with a special concern on the roles of pelvis and its muscles. The dynamic model including five joints, i. e. two ankles, two hips and one lumbosacral making up a multi-link system being driven by two pairs of muscles, the psoas major (PM) and glutaeus medius (GM). In coronal section, experimental data shows the ankle and lumbosacral sway in almost the same amplitude, whereas their phase difference is approximately equal to π. The results indicate that the trunk is keeping perpendicularly to horizon during the standing process. By defining the model's physical parameters, assuming that the corrective torque needed for balance keeping process is regulated by PID (stands for proportional, integral and derivative) control, the body sway can be simulated. The simulation result is quite consistent with the experimental data suggests that the pelvis is one of the most important structure in balance keeping, moreover, the dynamics of the present proposed balance keeping model is a quite useful model for analyzing the posture sway.