Magnetic Fluid Actuator Based on Passive Levitation Phenomenon

This article is concerned with the practical design and dynamic characteristics of a magnetic fluid actuator for which the working principle is based on the passive levitation of a non-magnetic body immersed in magnetic fluid subjected to magnetic field. This magnetic fluid actuator is composed of kerosene-based magnetic fluid HC-50, a pair of hollow solenoids whose north poles are placed face-to-face with each other, and a non-magnetic (paramagnetic) body made of aluminum. First of all, the design methodology for the magnetic fluid actuator is proposed based on the ferrohydrostatic relation including the gravitational force, the buoyancy force, and magnetic body force acting on magnetic fluid by magnetic field. After manufacturing the magnetic fluid actuator based on the proposed design criteria, its dynamic characteristics are experimentally investigated with the step and frequency responses of the displacement of the non-magnetic object to input coil currents. Through the comparison study between simulation analyses and experimental results, the effectiveness of the proposed magnetic fluid actuator is verified.