Switching and Intelligence in Spherical Stepper Motor

M.K. Rashid (Sultanate of Oman)


robotic joint, robot wrist, spherical motor, intelligent wrist.


Reducing the number of joints in 3-dimensional motion can save both space and required number of actuators. Such improvement can be achieved by using a spherical stepper motor SSM, It is basically a spherical rotor (rotating ball) placed inside a semi-spherical cavity (the stator). The developed electromagnetic forces between the permanent magnets that arranged on rotor surface (rotor poles) and the electromagnetic poles grouped at the inside surface of the stator can produce the essential torque for such motion. This work presents modeling and configuration design for such joint and suggest intelligent scheme for activating group of electromagnets to achieve the targeted motion. An algorithm is developed for obtaining the number, position, and, the effective arrangement of rotor and stator poles. The selection of acceptable arrangement allows the rotation in different directions and a broader motion range. Finite element method (FEM) is used to calculate the electromagnetic forces. The calculated forces are used in investigating a single step motion using a simple intelligent scheme.

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