Date of Award

Spring 1-1-2011

Document Type


Degree Name

Master of Science (MS)


Aerospace Engineering Sciences

First Advisor

Hanspeter Schaub

Second Advisor

Penina Axelrad

Third Advisor

Eric Frew


The thesis work develops an instantaneous power optimal attitude control for a spacecraft utilizing an integrated reaction wheel - flywheel system allowing for energy storage and return. The control is generally formulated to utilize an arbitrarily large number of reaction wheels, and is applicable to any system with redundant wheels spanning three-dimensional space. This is accomplished by manipulation of the wheel torque null motion such that the resulting attitude dynamics are not affected. By application of physical constraints on the wheel motor performance, the solution method to find the null torques is reduced to a hyperdimensional vector geometry problem, and the proper control torques are uniquely determined. The resulting power optimal control guarantees that the instantaneous maximum power is returned from the reaction wheels at all times. This control is then applied to a variety of control laws, demonstrating its behavior for a variety of control applications and initial spacecraft states. These include a velocity regulator control and attitude a velocity tracking control. Comparison to other relevant reaction wheel controls demonstrates the analytically developed instantaneous power optimal and minimum energy state seeking behavior. Finally, future developments are suggested, including the incorporation of wheel power return inefficiency and application of the developed methodology for integrated energy storage and power tracking.