High accuracy position adjustment and vibration isolation actuator with the controlled ferrofluid

An actuator for microposition adjustment and vibration isolation using the controlled ferrofluid is reported in this letter. The proposed actuator levitates on the ferrofluid which is affected by the combined dynamic magnetic field which is formed by coupling a permanent magnetic field with a controlled electromagnetic field. A controlled electromagnetic field is superposed on the permanent magnetic field in order to change the shape of the ferrofluid to ultimately move the actuator. The experimental results indicate that the proposed actuator can adjust the position with high accuracy and has a good dynamic performance. The proposed actuator can bear over 2 N loads, and the positioning accuracy is within 0.1 μm. The stroke of the actuator is about of ±30 μm with no load, and the stroke increases to ±75 μm at 2 N load. Its dynamic band with -3 dB amplitude attenuation and -90° phase is over 40 Hz. In addition, the displacement has a very good linear relationship with the input current. The results also demonstrate that the actuator can isolate vibration in a wide frequency range, as the low frequency vibration can be compensated by the active motion control, while the high frequency vibration can be attenuated by the elasticity and damping effects of the ferrofluid. Consequently, the proposed actuator has a significant potential for applications where the high accuracy micro-position adjustment and vibration isolation are needed.