Simulating overground turning in a VR-based linear treadmill

A Virtual Reality (VR)-based treadmill interface is developed for practicing turning skills in a linear treadmill. The interface incorporates self-paced speed control of treadmill and view angle control of virtual environment. The self-paced speed control allows users to voluntarily change walking speed so that they can reduce walking speed in a natural way near the corner of virtual corridors and increase walking speed while walking through straight virtual corridors. Based on the turning biomechanics in the literature, the VR interface implements voluntary control of view angle by user's head orientation for realistic turning in a linear treadmill. Through the pilot experiments with healthy volunteers, the realism of VR turning was evaluated by comparing the gait parameters in VR-based turning with respect to those of overground turning. Users controlled their head orientation angle properly without any prior instruction of how to walk through curved VR corridors in a straight treadmill. The head rotation angle during overground turning and VR turning was similar, and all users reduced walking speed and stride length near the virtual corners which is the same strategy of turning in the real world walking. The VR-based turning interface cannot implement exactly same biomechanics of turning in the real world walking because the linear treadmill does not allow lower body turning; however, it will be still useful in clinical settings for patients with neurological disorders to practice turning skills such as proper control of head orientation and overcoming hesitating behavior prior to turn.