A body-grounded kinesthetic haptic device for virtual reality

Abstract

Kinesthetic haptic devices can make us feel that we are touching or holding objects that are not actually there by applying a force directly onto a user's body. As a corollary of Newton's third law, these devices are typically attached to the ground or else they would not be able to apply a net force onto a user. Thus, kinesthetic haptic devices typically have small workspaces-the area in which they can be used-or are overly cumbersome and expensive. Consequently, they are incompatible with room-scale virtual reality, which allows users to move and walk within a room. The portable haptics interface overcomes this limitation because its wearable form factor means it's "grounded" directly to a user's back, making it portable. In other words, this device approximates the sensations of a kinesthetic haptic device while also being portable. The haptic device consists of a robotic arm that is mounted on a user's back, and its end-effector is attached to an HTC Vive controller, enabling use with virtual reality. A first example application uses the portable haptics interface to simulate the elasticity of a bow and arrow as a user pulls on the bowstring of a virtual bow. A second application renders haptic feedback for impacts by applying an impulse of in the appropriate direction when a user hits a tennis ball with a racket in virtual reality. In an evaluation, we asked users to shoot targets in virtual reality with and without haptic feedback. Our results suggest that haptic feedback increases spatial presence with a large effect size but does not affect involvement and experienced realism. Our results also suggest several improvements to the ergonomics of the system such as using thicker straps to better distribute the load. In summary, portable kinesthetic haptic devices such as the portable haptics interface provide room-scale virtual reality applications with the sense of touch without constraining users to a chair.