A personalized balance measurement for home-based rehabilitation

Accurate and real time balance estimation can be used to improve home based rehabilitation systems. We developed a personalized balance measurement, making use of the subject-specific center of mass (CoM) estimate offered by the statically equivalent serial chain (SESC) method and the zero rate of change of angular momentum (ZRAM) concept to evaluate balance during a series of dynamic motions. Two healthy subjects were asked to stand on a Wii balance board and their SESC parameters were identified. A set of dynamic motions was then recorded and the rate of change of centroidal angular momentum and the distance of the ZRAM point to the center line of the support polygon were obtained. A good match between both metrics was found. Additionally, we developed a real time application based on Kinect measurements that determines the ZRAM position, in real time, and displays it to the subject in the form of visual feedback. In this way the ZRAM can be used to evaluate balance in home-rehabilitation for any motion.