ATTITUDE CONTROL SYSTEM FOR SMALL SATELLITES

• US 20120199697A1
• Filed: 05/19/2010
• Published: 08/09/2012
• Est. Priority Date: 05/19/2009
• Status: Active Grant

• Current Assignee: University of Florida Research Foundation, Incorporated (State University System of Florida)
• Original Assignee: University of Florida Research Foundation, Incorporated (State University System of Florida)
• Inventors: Nagabhushan, Vivek, Fitz-Coy, Norman G., Leve, Frederick Aaron
• Granted Patent: US 9,199,746 B2
• Time in Patent Office: Days
• US Class Current: 244/165
• CPC Class Codes: B64G 1/286 using control momentum gyroscopes (CMGs)
• CPC Class Codes: B64G 1/428 Power distribution and management
• CPC Class Codes: Y10T 74/1282 with rotor drive

Abstract

Various embodiments of the present invention include an attitude control system for use with small satellites. According to various embodiments, the system allows rapid retargeting (e.g., high slew rates) and full three-axis attitude control of small satellites using a compact actuation system. In certain embodiments, the compact actuation system includes a plurality of single-gimbaled control moment gyroscopes (SGCMG) arranged in a pyramidal configuration that are disposed within a small satellite.

Claims

1. An attitude control system (ACS) for use with a pico- or a nano-satellite comprising:

a plurality of single-gimbaled control moment gyroscopes (SGCMGs) arranged in a pyramidal configuration and operable to provide three-axis attitude control of the satellite, wherein the ACS occupies a volume of less than about 100 mm×

100 mm×

50 mm of the satellite and has a mass less than about 500 grams.

2. The system of claim 1, wherein a total power consumption of the ACS is less than about 3 watts.

3. The system of claim 1, wherein a total power consumption of the ACS is less than about 2.5 watts.

4. The system of claim 1, wherein each of SGCMGs are configured to generate a torque of at least about 0.75 Nmm.

5. The system of claim 1 wherein the plurality of SGCMGs consists of four SGCMGs arranged in a rectangular pyramidal configuration with respect to one another.

6. The system of claim 1, wherein each of the SGCMGs has a longitudinal axis extending at an angle of about 40 degrees with respect to a central axis extending between the arrangement of SGCMGs.

7. The system of claim 1 wherein each of the SGCMGs comprises:

a flywheel assembly comprising;

a flywheel housing;

at least one flywheel rotationally disposed within the flywheel housing; and

a flywheel motor configured to drive the flywheel via a drive shaft of the flywheel,

wherein the drive shaft of the flywheel has a rotational axis oriented substantially perpendicular to a longitudinal axis extending through the SGCMG; and

a gimbal assembly comprising;

an L-shaped bracket comprising a first end surface and a second end surface; and

a gimbal motor having a rotational axis oriented substantially co-axial to the longitudinal axis of the SGCMG, the gimbal motor coupled to the second end surface and configured for rotating the flywheel assembly about the longitudinal axis of the SGCMG and between the first end surface and the gimbal motor.

8. The system of claim 7, wherein:

a central longitudinal axis extending between the arrangement of SGCMGs comprises a first end and a second end,

an apex of the arrangement is disposed adjacent the first end,

a base of the arrangement is disposed adjacent the second end,

the first end surface of the bracket of each gimbal assembly is disposed adjacent the apex of the arrangement, and

the second end surface of the bracket of each gimbal assembly is disposed adjacent the base of the arrangement.

9. The system of claim 7, further comprising a slip ring assembly coupled to the first end surface of the bracket for providing electrical power and feedback to the flywheel assembly.

10. The system of claim 7, wherein at least one of the flywheel motor or the gimbal motor comprises a framed DC motor.

11. The system of claim 7, wherein at least one of the flywheel motor or the gimbal motor comprises a frameless DC motor.

12. The system of claim 7, further comprising a gimbal plate disposed between the second end surface of the bracket and the gimbal motor and configured to engage both the second end surface of the bracket and the gimbal motor.

13. The system of claim 7, further comprising at least one flywheel motor driver board coupled to the flywheel assembly such that the flywheel motor driver board is configured to rotate with the flywheel assembly.

14. The system of claim 13, further comprising a pair of flywheel motor driver boards coupled to the flywheel assembly and one another such that the flywheel motor driver boards are configured to rotate with the flywheel assembly.

15. The system of claim 7, further comprising an inertial measurement unit coupled to the second end surface of the bracket of each of the plurality of SGCMGs.

16. The system of claim 1, further comprising a processor for controlling the plurality of SGCMGs, wherein the processor contains control and feedback algorithms for controlling the attitude of the satellite and steering logics for controlling the SGCMGs.

17. The system of claim 1, wherein the ACS is entirely disposed within an interior portion of a housing of the satellite.

18. The system of claim 1, wherein each SGCMG comprises:

a flywheel assembly comprising;

a flywheel housing having a first shaft and a second shaft, each shaft extending from an exterior of the flywheel housing along a longitudinal axis of the SGCMG, the first shaft extending from a first side of the flywheel housing and the second shaft extending from a radially opposite second side of the flywheel housing;

at least one flywheel rotationally disposed within the flywheel housing; and

a flywheel motor configured to drive the flywheel via a drive shaft of the flywheel,

wherein the drive shaft of the flywheel has a rotational axis oriented substantially perpendicular to a longitudinal axis extending through the SGCMG; and

a gimbal assembly comprising;

an L-shaped bracket comprising a first end surface and a second end surface, the first end surface defining a first opening configured for receiving the first shaft of the flywheel housing; and

a gimbal motor coupled to the second end surface and engaged with the second shaft of the flywheel housing, the gimbal motor configured for rotating the second shaft of the flywheel housing about the longitudinal axis of the SGCMG,

wherein the flywheel assembly is rotationally disposed between the first end surface and the gimbal motor when the first shaft is engaged within the first opening and the second shaft is engaged with the gimbal motor.

19. A single-gimbaled control moment gyroscope (SGCMG) comprising:

a flywheel assembly comprising;

a flywheel housing;

at least one flywheel rotationally disposed within the flywheel housing; and

a flywheel motor configured to drive the flywheel via a drive shaft of the flywheel,

wherein the drive shaft of the flywheel has a rotational axis oriented substantially perpendicular to a longitudinal axis extending through the SGCMG; and

a gimbal assembly comprising;

an L-shaped bracket comprising a first end surface and a second end surface; and

a gimbal motor having a rotational axis oriented substantially co-axial to the longitudinal axis of the SGCMG, the gimbal motor coupled to the second end surface and configured for rotating the flywheel assembly about the longitudinal axis of the SGCMG and between the first end surface and the gimbal motor.

20. A single-gimbaled control moment gyroscope (SGCMG) comprising:

a flywheel assembly comprising;

a flywheel housing;

at least one flywheel rotationally disposed within the flywheel housing;

a flywheel motor configured to drive the flywheel via a drive shaft of the flywheel; and

at least one flywheel motor driver board coupled to the flywheel housing,

wherein the drive shaft of the flywheel has a rotational axis oriented substantially perpendicular to a longitudinal axis extending through the SGCMG; and

a gimbal assembly comprising;

a bracket comprising a first end surface and a second end surface; and

a gimbal motor having a rotational axis oriented substantially co-axial to the longitudinal axis of the SGCMG, the gimbal motor coupled to the second end surface and configured for rotating the flywheel assembly about the longitudinal axis of the SGCMG and between the first end surface and the gimbal motor.

21. A method for providing three-axis attitude control of a pico- or a nano-satellite comprising:

providing an attitude control system (ACS) comprising a plurality of single-gimbaled control moment gyroscopes (SGCMG) arranged in a pyramidal configuration, wherein the ACS occupies a volume of less than about 100 mm×

100 mm×

50 mm of the satellite and has a mass less than about 500 grams; and

controlling the SGCMGs to produce a net torque on the satellite to adjust the attitude thereof.