Torque modeling of a permanent magnet spherical actuator based on magnetic dipole moment principle

Theoretical modeling in any engineering design is of paramount importance as it provides the interrelationship between variables being analyzed in a given condition. With regards to the design of an electromagnetic spherical actuator, torque modeling is crucial as it correlates the input parameters such as current to the output mechanical torque. In this paper, a new approach in torque formulation for this class of spherical actuator employing the magnetic dipole moment principle is being discussed. Derivation from first principle and the extension of this novel method in the acquisition of the resultant torque induced on the rotor is presented. The proposed approach circumvents the need for electromagnetic energy analysis within the air-gap between the rotor and stator poles and henceforth providing a direct computation of the resultant torque. The validity and soundness of this unique approach was verified against numerical results from the 3-D finite element model and empirical data.