Stuet: Dual Stewart Platforms for Pinch Grasping Objects in VR

Complex 3D shapes’ surfaces can be characterised using three shape descriptors: zeroth-order for rendering width; first-order to convey slope; and second-order for curvature. These shapes can be symmetric or asymmetric. To date, controllers in VR have been unable to render these properties in 3D. We present Stuet - a handheld VR controller that can render complex asymmetrical 3D objects for two-finger grasping and shape exploration. Stuet leverages dual 3 degrees of freedom (3-DOF) Stewart Platforms. This enables the contact plates for the fingers to be controlled individually, rendering object widths up to 75 mm and individual plate angles up to 30° in any tilt direction with respect to the vertical plane. We present the design and implementation of Stuet. We explain and benchmark its mechanical capabilities, present the inverse kinematics model required for its use, and report on a feasibility demonstration. Our results reveal that dual Stewart platforms offer new capabilities for asymmetric, advanced haptic interactions in VR.