Rendering of Virtual Volumetric Shapes Using an Electromagnetic-Based Haptic System

Mid-Air haptic devices have become an active area of research because of their potential impact to augmented/virtual reality. In this work, we develop an electromagnetic-based haptic interface to provide controlled magnetic forces on a wearable orthopedic finger splint with a single magnetic dipole. We model the electromagnetic forces exerted on the finger splint, optimize the design of the electromagnetic coils, and develop an impedance-type haptic rendering algorithm using position feedback. This rendering algorithm capitalizes on minimizing the error between the exerted magnetic force and the desired constraint force of a virtual three-dimensional (3D) object based on the position of the finger splint. In order to investigate the influence of incorporating position feedback, we conduct a comparative study for the same group of participants with (Case I) and without (Case II) position feedback. Our experimental results show that position feedback enables participants to achieve success rate of 66.87 ± 15.0% (n = 160) in distinguishing between the geometry of four 3D virtual objects. This rate is decreased to 55.15±15.8% (n = 160) in the absence of position feedback. Our analysis shows statistical evidence to conclude that the mean success rate for Case I is greater than that of Case II, at α = 0.1 and 90% confidence level.