Modeling and Analysis of a Biaxial Noncontact Lorentz Force Actuator

An analytical output force model is proposed for noncontact Lorentz force actuators (NLFAs), which are used for positioning and vibration isolation control of space sensitive loads that require an extremely quiet environment. A biaxial NLFA is presented. The actuator mainly consists of a closed magnetic circuit and a novel biaxial exciting circuit board developed by printed circuit board technology. The closed magnetic circuit consists of a C-type yoke and two permanent magnets and is simplified by the magnetic image method. A model of the spatial magnetic flux density in the air gap of the simplified closed magnetic circuit model is derived by the Ampere molecular current hypothesis and the Biot–Savart law. Finally, an analytical output force model of the actuator is obtained by calculating the magnetic flux densities and forces at selected finite points by considering the winding of the coils. The influences of the key dimensional parameters of the actuator on the output forces and their variations are studied using the derived analytical model. To verify the derived analytical model, a measurement setup is established based on an electronic scale. The experimental results show that the forces calculated by the proposed analytical model agree with the experimental values very well, and the deviation between the results is less than 4% when a rated force of 3 N is produced. Moreover, the relation between the number of selected points and computing time and the relation between the number of selected points and the extra calculation deviation, which are important for real-time control, are discussed. The proposed analytical model can help to improve the design efficiency and output force control of this kind of actuator.