The disclosed principles provide wearable body sensor systems and related methods to evaluate the whole body movement with or without an assistive walking device. More specifically, the disclosed principles monitor the whole body movement including COG & BOS with a 3-dimensional (3D) mapping over a given period of time. The disclosed principles provide a number of objectives, which include providing a wearable body 3D sensor network that can constantly monitor change of COG over the BOS during daily mobility to clinically evaluate older adults in maintaining upright posture and prevent falls in senior living communities and to clinically establish a quantitative mathematical model to determine the stability of the older adults.