Co-located 3D graphic and haptic display using electromagnetic levitation

This paper presents a novel system in which 3D graphics and high-fidelity haptic feedback can be generated seamlessly at the same physical location, without using mirrors or any other hardware other than a tool handle and the user´s hand in the line of sight of the user. A thin flat screen is placed directly above an array of coils so that electromagnetic forces and torques can be generated through the display to act upon magnets inside the tool handle held by the user. An array of 16 coils generates forces and torques upon 3 magnets embedded in the tool handle. A detailed model of the forces and torques generated on a single magnet from the current through a single coil was calculated analytically. The coil currents required to generate desired haptic interaction forces and torques on the tool handle are calculated from this model at each control update using redundant control methods. Forces of several Newtons gan be generated on the handle in any orientation within approximately 25 mm from the display. Tool position and orientation feedback is provided by an optical motion tracking sensor and infrared LEDs on the tool handle. The design and analysis of the prototype system is presented with results from a simple interactive environment.