Mechanical design & numerical electromagnetic analysis of a DC spherical actuator

Abstract

The focus of this research is to design and develop a spherical actuator for robotics applications. Unlike prior works, this project proposes a new type of a DC spherical manipulator that operates from the forces generated between pairs of air core electromagnetic coils and permanent magnets. The novelty of the proposed design is demonstrated by utilizing air cores as stator poles. This eliminates the drawbacks of existing spherical electromagnetic device where the performance is significantly hindered due to inherent detent force, hysteresis and saturation issue that arises from the ferromagnetic component. The ability to be able to accurately model the electromechanical phenomenon and predict the output torque is essential for high precision motion control. Numerical analysis of the electromechanical forces is performed using FEM software. Design experience in spherical actuators, unlike that of single DOF electromagnetic motors, has been limited and intricate due to the three dimensional nature of the output motion. This paper aims to present the design methodology and electromechanical analysis in a concise and orderly manner that may serve as a starting point for design optimization and research.