Detection of knee-joint motions using two linear accelerometers for pendulum test

In order to solve nonlinear differential equations concerning spinal stretch reflexes in the pendulum test, mutually synchronized values of the angle, angular velocity, and angular acceleration in the knee joint are frequently used as initial values. In this study, we propose a method which can detect both the angle and angular acceleration in the knee joint at the same time by simple operations on the outputs of two accelerometers. The principle of knee-joint motion detection, the evaluation of amplitude accuracy in the measured waveforms, and the evaluation of synchronization accuracy are successively described. © 2012 Wiley Periodicals, Inc. Electron Comm Jpn, 95(7): 41–48, 2012; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/ecj.11383