Decoupled, Open-Loop, Multi-DoF Rotation of a Spherical Permanent Magnetic Dipole Actuator
Name
ASPE 2020 Final Paper Submission - ID 85 (Tyler Hamer).pdf
Size
4.33 MB
Format
Adobe PDF
Checksum (MD5)
30e24484478289c55a35a003983e82a3
Author(s)
Hamer, Tyler Thomas
Chabot, Joshua
Trumper, David
Date Issued
March 2021
Publisher
American Society for Precision Engineering | Proceedings of the Thirty-Fifth Annual Meeting of the American Society for Precision Engineering
Citation
T. T. Hamer, J. Chabot, and D. L. Trumper, “Decoupled, open-loop, multi-DoF rotation of a spherical permanent magnetic dipole actuator,” in Proceedings of the Thirty-Fifth Annual Meeting of the American Society for Precision Engineering, Virtual. ASPE, 2020, pp. 52–57.
Version
Author's final manuscript
Abstract
A spacecraft’s attitude control system (ACS), which rotates the spacecraft in 3 degrees of freedom (DoFs), typically consists of multiple actuators such as reaction wheels, control moment gyroscopes (CMGs) and/or thrusters. SWaP (Size, Weight, and Power), torque generation, momentum storage, pointing stability, and reliability are all considered in choosing the actuators for an ACS. Reaction wheels have low torque generation and momentum storage whereas more efficient CMGs have large footprints due to their gimbal structures. The common use of PWM control for thrusters and mechanical bearings in reaction wheels and CMGs, introduces pointing jitter. Lastly, thrusters consume finite onboard propellant, resulting in limited mission duration.
Reaction spheres rotate a spacecraft about an arbitrary axis with an equal-and-opposite torque about their rotation axis when accelerated about that axis, similar to reaction wheels, or with an equal-andopposite gyroscopic torque when their rotation axis is reoriented, similar to CMGs. Thus, reaction spheres operated as CMGs are potentially high efficiency torque generation choices for an ACS. Also, reaction spheres are often magnetically levitated, eliminating the need for both gimbal structures and mechanical bearings. Therefore, reaction spheres potentially have higher momentum storage, pointing accuracy, and reliability for lower SWaP too.
While NASA first proposed reaction spheres over a half century ago, limitations with previous designs have kept the technology from commercialization [1, 2]. Recently, reaction spheres with a dipole permanent magnet as the rotor have appeared promising due to their mechanical simplicity and simple modeling despite their inherent underactuation [3, 4]. Torque cannot be generated about the rotor’s magnetization axis. In particular, Figure 1 depicts a bench-level prototype for a reaction sphere with a dipole permanent magnet as the rotor that was designed and fabricated. After modeling the reaction sphere and demonstrating closed-loop vertical suspension of its dipole rotor [5], commutation laws, which decouple the rotor’s dynamics, and multi-DoF-translation and-orientation sensing were implemented [6]. Afterwards, angular velocity estimation and decoupled, closed-loop, multi-DoF suspension of the rotor were demonstrated [7]. Building on the work from [5–7], this paper presents openloop rotation of the rotor about the stator’s X-,Y-, and Z-axes despite the prototype’s underactuation while closed-loop multi-DoF suspension is maintained.
Description
Thirty-Fifth Annual Meeting of the American Society for Precision Engineering. 20-22 October 2020, online
Subjects
Spherical Motor
Spherical Actuator
Spherical Reaction Wheel
Maglev Reaction Wheel
MIMO Rotation Control
Gimbaled Motion Control
Terms of Use
Creative Commons Attribution-NonCommercial-ShareAlike
Persistent DSpace Link
DOI of Published Version
https://www.proceedings.com/56764.html
