A hybrid approach for magnetic field analysis

A new form of 3-DOF spherical actuator having a rotor mounted with rare-earth-magnet poles is developed. Since the air-core coils are used in this actuator, the magnetic flux distribution is different from that of conventional electromagnetic devices. In this paper, the solution of the Laplace equation is used to derive the general form of the magnetic field, and a curve fitting approach is proposed to obtain the mathematical expression of the magnetic field. This mathematical representation of the 3D magnetic field can be applied to the torque modelling of the 3-DOF spherical actuator. Experimental studies have been conducted to determine the critical parameters and verify the effectiveness of the proposed approach.