A Mobile Motion Capture System Based on Inertial Sensors and Smart Shoes

Abstract

Motion capture systems play an important role in healthcare and sporttraining systems. In particular, there exists a great demand on a mobile motion capture system that enables people to monitor their health condition and to practice sport postures anywhere at any time. The motion capture systems with infrared or vision cameras, however, require a special setting, which hinders their application to a mobile system. In this paper, a mobile threedimensional motion capture system is developed based on inertial sensors and smart shoes. Sensor signals are measured and processed by a mobile computer; thus, the proposed system enables the analysis and diagnosis of postures during outdoor sports, as well as indoor activities. The measured signals are transformed into quaternion to avoid the Gimbal lock effect. In order to improve the precision of the proposed motion capture system in an open and outdoor space, a frequencyadaptive sensor fusion method and a kinematic model are utilized to construct the whole body motion in realtime. The reference point is continuously updated by smart shoes that measure the ground reaction forces.