Development of an optical sensor to measure deep muscle activity for motion intention detection in wearable robots

Abstract

Wearable robotic systems for rehabilitation or motion assist require the users motion intention to control them intuitively. According to the construction of the human anatomy, some of the muscles contributing to different motions are located in inner layers of the muscle structure. Thus, when using muscle activity to estimate the human motion intention, currently available measuring techniques cannot adequately differentiate muscle activity based on different layers. In this study, by measuring the scattered light intensity from the inner layer muscles for a projected light source into the muscles, we measure the inner layer muscle activity. Initially, the source-detector distance was calculated using the Monte Carlo Simulation, followed by the prototype development. With the evaluation experiments by measuring muscle activity for finger flexion and wrist flexion, it showed different source-detector distances allows the measurement from different layers of muscles with different amount scattered light at each case.