Actuation model for control of a long range Lorentz force magnetic levitation device

This paper describes control system development for a large motion range Lorentz force magnetic levitation device designed as a haptic interface device to be grasped by the hand. Due to the 50 mm translation and 60 degree rotation motion ranges of the desktop-sized device, the transformation between the vector of coil currents and the actuation forces and torques generated on the levitated body varies significantly throughout its motion range. To improve the dynamic performance of the device, the current to force and torque transformation can be recalculated at each control update as the levitated body moves about its workspace, rather than using a constant transformation calculated from the unrotated and centered position of the levitated body. The design of the device is presented and the new methods used to calculate coil current to force and torque transformations for levitation are described. Long-range trajectory following feedback control motion results are shown.