Assessment of total body kinematics using GPS

Purpose. Recent removal of the intentional positional errors by the United States Department of Defense for the global positioning system (GPS) provides new opportunities to measure unrestrained human motion in the outdoor environment. Further, there have been no investigations into the use of GPS for assessment of slow speed human movement. This study was designed to establish the relative accuracy and feasibility of using GPS for the assessment of human kinematics.; Methods. The GPS positional data was collected at ≈1 Hz on subjects performing various outdoor ambulatory tasks using three GPS receiver systems (Trimble GeoExplorer II, Garmin III, and a Garmin Vista). These tasks were specifically designed for assessment of the relative accuracy of GPS. The first task was a concentric circle test (CCT) (1, 2, 3, 4, 5, 10 m radii circles). The second task consisted of locomoting about a surveyed track, measuring the lane line distances. These two tasks were used to evaluate relative accuracy of selective availability off GPS and differentially corrected GPS. The third task consisted of an outdoor 3.5 km walk/run with a GPS receiver, which enabled a real-life field assessment of the relative accuracy of the GPS systems. (Abstract shortened by UMI.)...