Rendering 3D virtual objects in mid-air using controlled magnetic fields

In this study, we develop an electromagnetic-based haptic interface to provide controlled magnetic forces to the operator through a wearable haptic device (an orthopedic finger splint with single dipole moment) without position feedback. First, we model the electromagnetic forces exerted on a single magnetic dipole attached to the wearable haptic device, and derive magnetic force-current mapping for the dipole moment. Second, this mapping is used as basis for parameter selection of the electromagnetic coils of the haptic interface, dipole moment of the wearable haptic device, and the operating workspace of the system. The electromagnetic-based haptic interface enables three-dimensional (3D) virtual object rendering in mid-air within a workspace of 150 mm × 150 mm × 20 mm, using magnetic forces in excess of 50 mN. Participants experimentally demonstrate a 61% success rate in distinguishing the geometry of 4 representative 3D virtual objects. However, our statistical analysis shows that the ability of the participants to distinguish between geometries is not statistically significant, for 95% confidence level.