シミュレーションによる重心動揺検査の検討

概要

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A mathematical model of postural control while standing upright was formulated, and the results of stabilometry in normal subjects were simulated. Three modes of postural control : position control and velocity control of the body center of gravity (CG), and control of deviation between the projection point of CG (PCG) and the center of pressure (COP) of the body weight, were postulated. Our model was represented by two differential equations : equation of motion of PCG and equation of control of the velocity of COP in the three modes of postural control mentioned above. A random stochastic variable was also introduced as a control error. Equations were solved numerically with a computer, and the results were compared with the actual data of stabilometry of normal subjects.<BR>1) Each mode of control was indispensable for maintaining balance.<BR>2) Among the three modes of control, velocity control and deviation control played the main roles. It was necessary to change the velocity of COP in proportion to a weighted sum of the velocity of PCG and the deviation of PCG from COP.<BR>3) We could make the calculated drifting parameters roughly in agreement with the actual drifting parameters of the normal subjects by choosing reasonable values of model parameters.<BR>4) Calculated drifting patterns of the COP simulating unilateral vestibular hypofunction showed a deviation toward the affected side.