A Novel Tunable Electromagnetic Gravity Compensator with Low Natural Frequency for Precision Assembly

Precise positioning and vibration isolation are the key technologies in modern precision engineering, such as the precise assembly manipulators and UV lithography, where isolating precision components from the environmental disturbances during positioning is required. In this paper, a novel magnetic levitation gravity compensator employed in a precise assembly system is proposed, which can carry out high-precise positioning in ±5 mm stroke and superior vibration isolation performance attributed to its low levitation stiffness (72.11 N/m) and natural frequency (0.698 Hz). In order to design the gravity compensator with ultra-low stiffness and natural frequency, the analytical model of levitation force is deduced by equivalent surface current model and validated by FEM model. Moreover, a hybrid optimization strategy is utilized to obtain the optimal dimensional parameters of gravity compensator.