Extending the motion ranges of magnetic levitation for haptic interaction

We have developed two different magnetic levitation devices which provide unprecedented ranges of motion in both translation and rotation to a levitated handle to be used for tool-based haptic interaction. The first device levitates a handle attached to a thin spherical shell of flat coils suspended in permanent magnet fields using Lorentz forces. A novel coil type and magnet configuration provides motion ranges of 50 mm and 60 degrees in all directions, double the translation and triple the rotation ranges of the current maximum range Lorentz levitation haptic devices developed at Carnegie Mellon University. The second device uses a planar array of cylindrical coils to levitate a platform of one or more magnets. By using redundant control methods and an experimentally measured high resolution model of the forces and torques generated on the levitated magnets from each coil, the translation range of the magnet in horizontal directions and its rotation in all directions and can be extended potentially indefinitely. The present prototype uses 10 coils to levitate a single magnet over a 80times60 mm planar range, a 30 mm vertical range, and a tilt range of 40 degrees, or to control the yaw rotation of a pair of magnets over 360 degrees. Design and control methods are presented with preliminary motion trajectory results from both devices.