Permanent Magnetic Dipole Spherical Actuator Back-Iron for Improved Power Efficiency & Shielding
Name
ASPE 2023 Final Paper Submission - ID 23AM81 (Tyler Hamer) vRR.pdf
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16.21 MB
Format
Adobe PDF
Checksum (MD5)
77d5cd3f5fcee292bdc2bbeb985123f9
Author(s)
Hamer, Tyler Thomas
Chabot, Joshua
Trumper, David
Date Issued
May 2024
Publisher
American Society for Precision Engineering | Proceedings of the Thirty-Eighth Annual Meeting of the American Society for Precision Engineering
Citation
T. T. Hamer, J. Chabot, and D. L. Trumper, “Permanent Magnetic Dipole Spherical Actuator Back-Iron for Improved Power Efficiency & Shielding,” in Proceedings of the Thirty-Eighth Annual Meeting of the American Society for Precision Engineering, Boston, MA, USA. ASPE, 2023, pp. 358–363.
Version
Author's final manuscript
Abstract
A momentum control system (MCS), a set of 3 or more reaction wheels (RWs) or 4 or more control moment gyroscopes (CMGs), typically exchanges angular momentum with a spacecraft’s body to alter/maintain the spacecraft’s attitude (orientation) so as to not consume thrusters’ limited fuel. Simpler, less power efficient RWs are used more in smaller, less agile spacecraft for their compactness despite their lower torque generation, whereas power efficient CMGs are used more in larger or more agile spacecraft for their higher torque generation despite their complexity and large footprint due to their gimbal structure. Both actuators usually use rolling element bearings, whose stiction and vibration transmission negatively impact pointing precision. Further, 2 RWs in both the Hubble-and Kepler-Space Telescopes as well as 1 CMG in the International Space Station and 2 CMGs in the WorldView-4 Imaging Satellite malfunctioned due to their mechanical bearings [1], resulting in decreased mission life.
An alternative to RWs and CMGs are reaction spheres, which rotate a spacecraft about an arbitrary axis with either an equal-and-opposite (1) torque about their spin axis like RWs when accelerated about that axis or (2) gyroscopic torque like CMGs when their spin axis is gimbaled (tilted). Reaction spheres are often magnetically levitated, eliminating (1) mechanical bearings for increased pointing accuracy and reliability, and (2) gimbal structures, resulting in a compact, multi-axis actuator able to replace multiple single-axis RWs and CMGs for a more compact MCS. Thus, reaction spheres operated as CMGs potentially solve the RW-CMG trade-off.
While NASA first proposed reaction spheres over a half century ago, previous designs’ limitations kept the technology from commercialization [2; 3]. For example, reaction spheres with a dipole permanent magnet (PM) for a rotor cannot generate torque about the rotor’s magnetization axis about which the dipole PM field is continuously rotationally symmetric [4; 5]. Despite this inherent underactuation, Figure 1 depicts a reaction sphere bench-level prototype with such a rotor for which simultaneous decoupled, closed-loop, multi-DoF suspension and rotation along/about the stator’s X-, Y-, and Z-axes has been demonstrated [1; 6–8]. Building on this work, this paper presents analytic models and numeric simulation for adding a back-iron shell which contains and concentrates the PM field to respectively shield the spacecraft and increase torque per power.
Description
Thirty-Eighth Annual Meeting of the American Society for Precision Engineering. 12-17 November 2023, Boston MA USA
Subjects
Spherical Motor
Spherical Actuator
Spherical Reaction Wheel
Maglev Reaction Wheel
Motor Back-Iron
Magnetic Shielding
Terms of Use
Creative Commons Attribution-NonCommercial-ShareAlike
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DOI of Published Version
https://www.proceedings.com/74477.html
