Mita K, Akataki K, Itoh K, Nogami H, Katoh R, Ninomi S, Watakabe M, Suzuki N
Institute for Developmental Research, Kasugai, Japan.
Front Med Biol Eng. 1993;5(3):201-13.
It has been reported that accuracy in the measured point of force application depends on the position and magnitude of load. The aim of this study is to investigate the error in measuring the body center of pressure in a standing posture with a force plate and to improve the accuracy by proposing a correction algorithm. The measurement of the point of force application with a calibrated load demonstrated its co-ordinates, which were scaled down towards the zero co-ordinate and moved parallel relative to the true co-ordinates. This trend was exaggerated with any decrease in magnitude of the load. The root mean square (r.m.s.) and maximum of errors at light load of 10 kg were 10 and 18 mm in the X axis, and 6 and 12 mm in the Y axis, respectively. The error seems to result from such causes as (i) non-linearity of the load cell, (ii) deformation of the top plate due to load application and (iii) differences in characteristics among individual load cells, including amplifiers. A mathematical representation of the measured point of force application accounting for these causes of error has been made and an algorithm for estimating the true point at any magnitude of load with only one correction equation is proposed. Actual correction of the measured point demonstrated an expected improvement in the r.m.s. error to less than 1 mm at any magnitude of load greater than 10 kg and the validity of this algorithm was confirmed.
据报道，力施加测量点的准确性取决于负载的位置和大小。本研究的目的是调查使用测力板测量站立姿势下人体压力中心的误差，并通过提出一种校正算法来提高准确性。使用校准负载对力施加点进行测量，结果显示其坐标朝着零坐标缩小，并相对于真实坐标平行移动。随着负载大小的任何减小，这种趋势都会被夸大。在10 kg轻负载下，X轴的均方根（r.m.s.）误差和最大误差分别为10 mm和18 mm，Y轴分别为6 mm和12 mm。误差似乎源于以下原因：（i）称重传感器的非线性；（ii）由于施加负载导致顶板变形；（iii）包括放大器在内的各个称重传感器之间的特性差异。已经建立了考虑这些误差原因的力施加测量点的数学表示，并提出了一种仅用一个校正方程就能估计任何负载大小下真实点的算法。对测量点进行实际校正后，在任何大于10 kg的负载大小下，均方根误差有望改善到小于1 mm，从而证实了该算法的有效性。
