Coarse-fine residual gravity cancellation system with magnetic levitation

The authors describe a six degree-of-freedom active experiment isolation system designed to cancel out residual accelerations during zero-gravity parabolic flights. The isolation system consists of a fine-motion magnetic levitator whose stator is transported by a conventional coarse-motion stage or by a robot. The levitator uses wide-gap voice-coil actuators and has the dual purpose of isolating the experiment platform from aircraft vibrations and actively cancelling residual accelerations through feedback control. The robot tracks the levitated platform to keep the levitator´s coils centered within their matching magnetic gaps. Aspects of system design, an analysis of the proposed control strategy. and simulation results are presented. Feasibility experiments using a PUMA 500 and a magnetically levitated robot wrist are discussed