Locomotion interfaces represent a new field, and at this early stage there are many uncertainties about the best approaches. This exploratory research is concerned with the mechanical display of slope, inertia, and turning on a treadmill-based locomotion interface, the Sarcos Treadport. The Sarcos Treadport comprises a linear tilting treadmill, an active mechanical tether, and a CAVE-like visual display. The active mechanical tether, which is the unique aspect of the Treadport, measures user position and applies axial forces to the user. Although the treadmill is a linear device, the research aims to show that the tether coupled to the visual display provides a reasonable basis for turning control. The force-producing capability of the active tether offers the unique ability to simulate inertial forces during running, which are otherwise absent because the user is stationary. Treadmill tilt mechanisms are typically too slow to display rapid slope changes. By pulling on the user to simulate uphill walking and pushing for downhill walking, the active mechanical tether can simulate gravity. The PIs propose to conduct a series of biomechanical, modeling, and psychophysical studies to demonstrate the proposed motion displays for turning, inertial force, and slope using an active mechanical tether. The objective is to show that adding a mechanical tether to linear treadmills is a useful and reasonable approach towards locomotion interfaces, and that the proposed locomotion display approaches have some scientific basis and are effective from a user standpoint.
