기계공학부 구성원들의 많은 관심과 참여 부탁드립니다.

▣ Title: A Permanent Magnetic Dipole Reaction Sphere for Spacecraft Attitude Control

▣ Speaker: Tyler Hamer

▣ Affiliation: MIT Lincoln Laboratory

▣ Date: 2021. 9. 17.(Fri) 14:00

▣ Venue: Online(Zoom)

▣ Host: Prof. Junyoung Yoon

▣ Abstract

This talk presents decoupled, closed-loop, multi-DoF suspension and rotation of a spherical dipole permanent magnet. The 38.1 mm (1.5 in) diameter spherical NdFeB magnet is used as the rotor in a bench-level prototype reaction sphere actuator for spacecraft attitude (orientation) control. 12 equidistant stator coils, each centered on one face of the dodecahedron stator, levitate the rotor in three dimensions with micron resolution using translation feedback from 12 optical sensors and rotate the rotor up to 13600 rpm (1420 rad/s) about an arbitrary axis using rotation feedback from 12 Hall effect sensors even though torque cannot be generated about the magnetization axis. Reaction spheres rotate spacecraft either with an equal-and-opposite torque about their rotation axis when accelerated about that axis, similar to reaction wheels or with a more efficient gyroscopic torque used to reorient their rotation axis, similar to control moment gyroscopes (CMGs). This talk focuses on the modeling, design, fabrication, control, and operation of a prototype for generating reaction torque. Compared to conventional reaction wheels and CMGs, reaction spheres can potentially generate higher torque and store more angular momentum for lower SWaP (Size, Weight, and Power), lower pointing jitter, and over longer mission durations due to the elimination of mechanical bearings and gimbal structures. Thus, such a reaction sphere can potentially enable attitude control performance traditionally found in large, expensive, monolithic spacecraft in fleets of small, low-cost spacecraft as the demand for small, low-cost spacecraft only continues to increase.

Zoom:https://us02web.zoom.us/j/3824385800?pwd=OUFEWmtWaVpKcmhlU29ZcTloSkNqUT09