DEVELOPMENT OF A TOTAL ANALYSIS SYSTEM FOR HUMAN WALKING COMBINED WITH THE PRESSURE DISTRIBUTION MEASURING APPARATUS

Abstract

In this experiment the measurements were executed by specially developed apparatus, i. e., a force plate, a tactile image sensor system which measures the pressure distribution of the foot contact area, and an automatic stepmeter which measures the stride length and stride frequency. Video cameras were also used for the kinesiological analysis. All the apparatus were synchronized. We conducted experiments with 30 male and 30 female subjects to process the results statistically. For the walking speed we set up three categories: slow, ordinary, and fast. Walking speed was determined according to each person's subjective point of view. Ten trials in each category of walking speed were recorded and analyzed. The vertical component of the foot-ground reaction force measured by the force plate generally has first maximum amplitude, first minimum amplitude, and then second maximum amplitude during the stance phase. Walking speed has a high positive correlation with the first maximum amplitude and a high negative correlation with the first minimum amplitude. These results are similar to those in previous studies. But there was a problem with the relation between walking speed and the second maximum amplitude. One study pointed out a positive correlation, while another indicated no correlation between them. Previous studies, however, made the calculation for the sample as a whole. Our experiment reveals that there are differences between individuals. There is a positive correlation in some subjects, a negative correlation in others. In the remaining subjects there was no correlation between them. The automatic stepmeter measures the temporal change in the length of the sole contact area for each millisecond at a resolution of 5mm. The measured data reveal that more than 80 percent of the sole length (without toes) has already made contact with the floor at the moment of the first maximum amplitude of the vertical component of foot-reaction force. Trajectories of the point of application are calculated from the data on the force plate. The trajectory goes from the heel straight to the point between the head of the second and third metatarsal bones. There its speed slows down; then it goes toward the big toe with an angle of approximately 35 to 45°. This corresponds to the triangle structure of the supporting plane of the foot. The "isobarogram" and "maximum pressure isobarogram" were drawn based on the data from the tactile image sensor. From these illustrations, we see that the pressure at the heel, at the head of the second and the third metatarsal bones, and at the big toe or the second toe increases while walking. The pressure at these points is compared for each category of the walking speed. The differences were smallest at ordinary speed. It suggests that the construction of the sole is best adapted to this walking speed.