2010 Volume 25 Issue 1 Pages 71-77
[Purpose] We estimated two parameters based on control engineering, namely natural frequency (ω) and damping ratio (ζ) estimated by using modeling of standing posture in tilting-recovery motion, and examined the relation between the characteristics of motion, standing balance and the estimated parameters. [Subjects] Twelve healthy volunteers participated in the experiment. [Methods] Movements at the ankle and hip joints in tilting-recovery motion were measured under four conditions of standing stability. The parameters ω and ζ were estimated by applying measured joint movement data to a one-link model having only an ankle joint, or a two-link model having ankle and hip joints, and the relation with characteristics of motion corresponding to change of stability were analyzed. [Results] The unstable characteristics of standing balance appeared as change of hip movement, and the correlation of stability with the two parameters in the two-link model was evident. [Conclusion] The results suggest that the parameters ω and ζ obtained by considering hip movement reflect dynamic balance in standing posture.
