Haptic motion: Improving sensation of self-motion in virtual worlds with force feedback

Haptic feedbacks are usually used to provide a sensation of interaction with virtual or distant objects. These feedbacks give an access to the physical properties or constraints of these objects in a given environment. In the present study, we wondered if a haptic feedback in the hands can provide an enhanced sensation of whole-body self-motion in virtual worlds. We designed two experiments where subjects were visually immersed in a moving virtual environment and exposed, in parallel, to a force feedback stimulation in hands coherent with the virtual camera motion. In the first experiment, the motion was in a straight line combined with a force feedback acting only on Z-axis (longitudinal) and with an amplitude proportional to the acceleration of the virtual camera. We showed that the visuo-haptic stimulation produces a higher sensation of self-motion compared to the visual feedback alone. In the second experiment, we tested our method with a more complex virtual camera trajectory, inducing an acceleration vector of the virtual camera owning components in each 3D axis. Based on the difference of orientation between the velocity and acceleration vectors of the camera, we showed that the force feedback, providing the most important sensation of self-motion, has the same 3D orientation and is proportional in magnitude to the acceleration of the virtual camera. These results highlight the way visual and haptic cues interact together to provide a self-motion sensation. Taken together our results suggest new applications of force-feedback devices in VR, for the purpose of enhancing self-motion sensations.