Effects of Magnetic Pole Design on Orientation Torque for a Spherical Motor

Abstract

This paper investigates the effect of pole layouts of permanent magnets (PMs) and electromagnets (EMs) on inclination torque of a multidegrees of freedom (DOFs) spherical motor (SM). Unlike conventional electromagnetic actuators capable of controlling a single DOF motion in spinning, the SM offers a unique ability to control orientation of a spinning rotor. Although the motor offers such attractive feature, it is essential to generate torque to maintain at a desired orientation. However, it is challenging to design the motor enhancing the orientation torque due to a limited number and space for PMs and EMs involved in orientation motion unlike spinning. This paper presented a new design of the SM maximizing inclination torque by evaluating the number of PMs and materials of structure such as iron and aluminum. Then, the torque of the proposed designs has been compared by results from a numerical finite-element method technique as well as an experiment. Finally, dynamics and control simulations are demonstrated to ensure the effective enhancement of the proposed SM.