A small-sized spherical stepping motor and the controls

This paper describes a small-sized spherical-surface stepping motor and its control algorithm, which has been developed successfully in Yasakawa Electric Corporation, Japan. The motor consists two arc-shape variable-reluctance (VR) linear stepping motors, and is controlled precisely by micro stepping current. Host controller can control up to four stepping motors or servomotors simultaneously or separately. Compared to other spherical-surface motion machines, this motor system has been characterized by compact-structure, light mass, high positioning precision, large moving range, high speed and large torque. The experimental results have shown that this motor and the control system are very effective solutions as important actuators in robots industry (intelligent robot's eyes and limb-joints), astronomical apparatus and many other fields.