Configuration Design and Intelligent Stepping of a Spherical Motor in Robotic Joint

Abstract

Reducing the number of joints in robotic arms can save both space and number of actuators. Incubation of spherical joint carrying inserted permanent magnets on its surface by a semi-spherical stator implanted with electromagnets can provide such advantages. The developed forces between the permanent magnets arranged on the rotor surface (rotor poles) and the activated electromagnets inside the stator can produce the required torque for joint motion. Such arrangements are called spherical stepper motors (SSM). This work presents a modeling and configuration design for such joints. An intelligent scheme is developed for activating the appropriate pairs of electromagnetic stator poles to achieve the targeted motion. In addition, an algorithm is built for obtaining numbers, positions and an effective arrangement of rotor and stator poles. Reaching acceptable arrangements can produce wider motion range in different directions. Dimensionless charts for electromagnetic forces are created using the FEM. These charts are used in investigating a single step motion using a simple fuzzy scheme.