ヒトの立位バランスの評価 : 追従性と学習効果

Abstract

The object of this study is to conduct mechanical evaluation judgments of the ability of people to maintain balance in a standing posture. The authors developed a system which swings a plate on which a person is standing and measures the resulting plate torques and the angles of inclination of each part of the body element at that time (Posture Control System). This swing generator generates smooth rolling and pitching movements, and the movement cycle and direction can be changed freely with an N. C. controller. As a major characteristic of this system, changes of balance caused by swing disturbances such as changes of torque acting in the plate can be measured. This actuator (blush less servo motor) is used not only to generate motions but to serve the function of torque sensor. Small torque balance inclinometers are used to measure the angles of inclination of each part of the body (12 sections). Moreover, a tri-dimensional model of the body is constructed to calculate the center of gravity and center of force operating in each part of the body. In this report, the authors used this Posture Control System and tried the following: 1) Evaluation of ability of normal healthy old people to maintain balance in a standing posture by torque of the sole. 2) Evaluation of learning phenomena by fuzzy linear regression analytical methods for general evaluation of standing ability. Tests of evaluation of the traceability were conducted with normal young healthy people as well as with normal old healthy people as subjects. Tests under the same conditions in which people swung the plate while standing on two legs showed the following characteristics. In the old people, width and standard deviation of delay for distance (dθ) were large, and the average of dθ was large in the negative direction. The old people fell far below the young people in traceability of balance for a change of swing direction. Moreover, for individuals with unknown functional disorders, learning phenomena are discussed in the framework of possibility; the authors employed the fuzzy regression model to analyze learning phenomena. This approach enables us to understand two characteristics of the learning effect. One is the formation of competence at swing disturbance. The other is stability. For example, young and old people are much the same at the formation of competence. But the old people are inferior to the young in stability. In rehabilitation training, the results of training can be expected in the future as each handicapped person has his own aim. It is considered a useful application to conduct a measuring experiment for many subjects and to change the results into a data base in this system.