The Snail: A Wearable Actuated Prop to Simulate Grasp of Rigid and Soft Objects in Virtual Reality

The Snail is a wearable haptic interface that enables users to experience force feedback when grasping objects in Virtual Reality. It consists of a 3D-printed prop attached to the tip of the thumb that can rotate thanks to a small actuator. The prop is shaped like a snail to display different grasping sizes, ranging from $ 1.5\,\text{cm}$ to $ 7\,\text{cm}$, according to its orientation. The prop displays the force feedback, so forces over $ 100\,\text{N}$ can be displayed between fingers using small and low-power actuation. Very rigid objects can be rendered when the prop remains static, but rotations when the users grasp the prop also allow for the simulation of soft objects. The Snail is portable, low-cost, and easy to reproduce because it is made of 3D-printed parts. The design and performance of the device were evaluated through technical evaluations and 3 user experiments. They show that participants can discriminate different grasping sizes and levels of softness with the interface. The Snail also enhances user experience and performances in Virtual Reality compared to standard vibration feedback.