Development of Three-Dimensional Reaction Wheel Using Spherical Rotor

摘要

This paper describes the development of three-dimensional reaction wheel using a sphere. The system enables three-dimensional motion in terms of rotation of the spherical wheel without mechanical constraints. The system consists of a spherical wheel as a rotor, actuators composed of multilayer piezoelectric ceramics, and sensing system to measure rotational speed. Most of system to generate three-dimensional motion requires very complex mechanism using gears and links, and special mechanism. Using three piezoelectric actuators as stator, the proposed system reduces size and weight in comparison with conventional mechanical system. Optical sensors, which are assembled into the system, measure the angular velocity of the spherical reaction wheel in any direction. The developed reaction wheel system, therefore, can be applied to small satellites with inherent problems such as space and weight limits. A PID controller is used for control of direction and angular velocity of the spherical wheel. The proposed system is successfully employed to drive the spherical wheel up to 100 rpm.