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

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 $\pm$ 15.0% $(n=160)$ in distinguishing between the geometry of four 3D virtual objects. This rate is decreased to 55.15 $\pm$ 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 $\alpha=0.1$ and 90% confidence level.