Date of Award

Spring 1-1-2015

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Aerospace Engineering Sciences

First Advisor

Hanspeter Schaub

Second Advisor

Brandon Jones

Third Advisor

Jeffrey Parker

Abstract

Spacecraft generally require multiple attitude control devices to achieve full attitude actuation because of the limited control authority a single, traditional device can provide. This work presents a new momentum-exchange device that has the potential to replace traditional attitude control systems with a single actuator, in turn providing mass, volume, and power savings. The proposed actuator consists of a spherical dipole magnet enclosed in an array of coils that are fixed to the spacecraft body. Excitation of the coils as prescribed by the control law accelerates the dipole magnet in such a manner as to produce a desired reaction torque for orienting the spacecraft. The coils also control the magnet's position inside the spacecraft body via a separate control law, which is necessary because of the non-contact nature of the device. Analytical force and torque models are developed and are used in an attitude regulation maneuver. Simulations conducted so far indicate that full attitude control is possible from a single device despite the axisymmetric field of the magnetic dipole rotor, which was anticipated to cause control issues. Finally, the single actuator system is compared to a cluster of three reaction wheels, illustrating how this device can provide mass, volume, and power savings.

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