Magnetic field analysis of a VCM spherical actuator

A spherical actuator can support multi-degree-of-freedom (DOF) motions. Among the various spherical actuators that have been developed, a spherical actuator that uses a voice coil motor (VCM) has a simple driving principle and a uniform torque constant. Magnetic field analysis is crucial for improving the performance of an actuator. In this paper, a three-dimensional field solution is presented for spherically polarized permanent magnets. The magnetic flux density distribution in the air gap is calculated using the charge model, current model, and method of images. The actuator torque is computed by the calculated magnetic flux density. Finally, the analytically computed torques are verified by finite element method (FEM) simulations and experimental results.