Tmh. Dijkstra, A gentle introduction to the dynamic set-point model of human postural control during perturbed stance, HUMAN MOVE, 19(4), 2000, pp. 567-595
Three models of increasing complexity to capture three observed phenomena o
f postural control are described. The first-order model mimics the increase
in standard deviation of sway with eyes closed, but none of the other phen
omena. The damped spring model captures both the increase in standard devia
tion of sway with eyes closed and the change from phase-lag to phase-lead w
ith increasing frequency of oscillation of a visual surround. The final mod
el, the dynamic set-point model, extends the damped spring model by a degre
e of freedom that reflects the observed slow drift in baseline. Under the a
ssumption of a strong coupling to positional information, the dynamic set-p
oint model predicts a dependence between natural frequency and position cou
pling constant of the damped spring model. It is shown that this prediction
is borne out in data obtained from haptically perturbed stance but not in
data obtained from visually perturbed stance. (C) 2000 Published by Elsevie
r Science B.V. All rights reserved.