A Reaction Sphere for High Performance Attitude Control

Our innovative reaction sphere (Doty pending patent application serial number 61/164,868) has the potential to provide much higher performance than a conventional reaction wheel with substantially fewer resources. Using our proposed technology, a single reaction sphere can control three axes, substantially reducing mass, power, and cost when compared to a three wheel system. This device has no bearings: its spherical rotor is suspended within the stator by magnetic forces. Magnetic suspension reduces jitter, especially in a station-keeping mode where the torque and suspension forces can be reduced to a minimum. With clearances of ~1 mm and no critical balance requirements, this device has very loose mechanical tolerances, further reducing cost. For initial development we propose a version suitable for control of a 1-3 kg Cubesat. At this scale, where spacecraft moments of inertia are very small, our low jitter torque, simplicity, and low cost are most advantageous. We also believe this approach is most likely to lead to an early flight opportunity. More »