Research on a Low Stiffness Passive Magnetic Levitation Gravity Compensation System with Opposite Stiffness Cancellation

In the nanopositioning system, such as the wafer stage in a lithography machine, vibration isolation is applied to decrease the influence of the lower basic frame on the upper positioning system. At present, the combination of passive gravity compensation with magnetic force and active stabilization control using linear actuators is a potential solution for vibration isolation. In this paper, an opposite stiffness cancellation method which can be used to decrease the vertical stiffness of a passive gravity compensation system is proposed. By comparison, the new passive gravity compensation system has less stiffness than that of the conventional structure. Lastly, a prototype is manufactured and tested.