Abstract
To identify a posture control system without external disturbance, the maximum likelihood method was applied to data of antero-posterior sway during quiet stance. Ankle joint moment was measured by means of a force plate. Sway angle of a body was measured by a position sensor camera which detects positions of a light emitting diode attached to the body.
Using data of 500 input-output pairs, which were sampled every 0.1s, parameters of a sensory feedback path were estimated and frequency response functions were calculated. These frequency response functions showed derivative characteristics that is necessary for the stabilization of a posture control system. The gain characteristics of a sensory feedback path under closed-eye condition tended to be greater than those under open-eye condition.
