Damping pattern of lower-leg supporting force released at the beginning of pendulum-test

Abstract

In knee-joint angular acceleration waveforms measured for pendulum-test of seated subject, some measurement errors may be caused by lower-leg supporting force remained after its start (residual force). Authors had corrected them temporally by approximating its damping pattern with a straight line. In this panel, we derived a better damping pattern from residual force measured on the way of the pendulum test. The residual forces in each of two normal subjects were measured 5 times under 3 initial knee-joint angles by a load sensor attached to palm for the lower-leg supporting. Normalization of measured damping patterns showed that it could be approximated by a quadratic function -a₁ t²-a₂ t+1, where a₁, a₂ were constants, the values of which might differ every measurement. Building such quadratic function in the inverse simulator for estimating spasticity, it is expected to be able to correct the influence of the residual force.