TG2 : ungrounded weight feedback in virtual reality using pendular mechanical actuation

Abstract

In this work, we introduce a new type of handheld haptic device capable of rendering forces by shifting a mass element on a hemisphere around the hand. The technique ex ploits gravity to recreate torque at the wrist, which generates the illusion of weight. With virtual reality becoming more popular, new ideas to increase the immersion in these en vironments start appearing. Devices capable of haptic feedback are being developed with different approaches to the same problem, generating force in the real world that increases immersion in a virtual world. Instead of using the traditional approach of a grounded me chanical actuated device, we used a lightweight 3D printed handheld device that utilizes an inverted pendulum driven by mechanical actuators to convey perception of different weights in VR as the user grabs virtual objects. To evaluate the quality of the stimulus provided, we designed a psycho-physical study composed of two tasks that consist of the user interacting with objects in a virtual environment. The first one was ordering a set of four cubes by weight, from lightest to heaviest. The second task was matching the weight of two bars with different densities by controlling their length and radius. We found that the stimulus allows to discriminate different weights that the response time is shorter as the weight difference between objects increases. We also found statistically significant differences in precision and response time between a pair of lightweight objects and a pair of heavyweight ones. Qualitatively, the users identify the stimulus as weight in most cases.