Wearable Sensor Systems for Human Motion Measurement

Abstract

In this thesis, various wearable sensor systems were developed to measure human motions. Measured human motion included the gait motion of lower extremity and finger motion. The gait motion was measured by using inertial measurement units (IMUs) and manually developed ground reaction force (GRF) sensors. Four IMUs measured hip, knee and ankle joint angles by calculating rotational matrix of each sensor. Four GRF sensors were made of silicone tube and pressure sensors that measured pressure changes inside the tubes. The measured joint angles and GRF by developed system were compared with a camera-based motion capture system and a fixed force plate. On the other hand, a wearable soft sensor system was developed to measure finger motions, which consisted of soft and stretchable silicone filled with the electro-conductive liquid metal, called eutectic Gallium-Indium(EGaIn) alloy. Due to the light weight and highly stretchable properties of the silicone, the wearable sensor system allowed natural movements for the users and it was able to adapt to various hand sizes. In the proposed system, the flexion and extension of fingers and abduction of index finger could be measured. The accuracy in finger motion measurement was verified by the camera-based motion capture system. Lastly, a modeling of human joint with 3 degrees of freedom (DOFs) was investigated. The purpose of the modeling was to model the carpometacarpal (CMC) joint of the thumb more precisely. The glenohumeral (GH) joint was used to verify the model due to its similar behavior with CMC joint. The result was validated by using a camera-based motion capture system.