A System to Facilitate Early and Progressive Ambulation Using Fiducial Markers

This paper presents a camera-based physical movement assessment that is the key part of a patient ambulation monitoring system. We assess the feasibility of the system and address its main parameters and limitations related to encouraging early and progressive ambulation. This system uses regular, off the shelf webcams in combination with fiducial markers and computer vision to accurately quantify the movement of a human subject. Using a perspective-n-point transform the location of the fiducial markers is obtained. The extracted coordinates are then filtered before calculating the distance traveled by the markers, and the person wearing the markers by extension. In measuring the distance traveled by a subject when moving in the field-of-view, we have achieved average error of less than 9.11% and 4.38% for a single- and dual-camera systems, respectively.