Measurement of muscle motion for improving accuracy of body-mounted motion sensor

A new method of measuring joint angle using a combination of 3D accelerometers and reaction force sensors is presented. Muscle motion is a common source of error to all body-mounted sensors. The effect of skin artefact was minimized based on the estimation of muscle motion measured using a new reaction force sensor banded with human body segment. The force sensor was designed using pressure sensitive electric conductive rubber (PSECR). Fourier transform of the total pressure forces induced by body-mounted motion sensor modules was implemented to analyse frequency property of muscle motion of human body surface. We processed data from 3D accelerometers using measurements of muscle motion including the total pressure force and two-directional coordinates of center of pressure (Cop). Experimental study was implemented to verify the new sensor system proposed for estimation of knee joint angles, and measurements of the developed sensor system showed a high correlation to the results from the optical motion analysis system in the walking analysis experiment.