Spacecraft attitude control strategy for reducing disturbance torques

Patent metadata

Field	Value
Publication number	US-11273933-B2
Application number	US-201916425296-A
Country	US
Kind code	B2
Filing date	May 29, 2019
Priority date	May 29, 2019
Publication date	Mar 15, 2022
Grant date	Mar 15, 2022

Abstract

A control system for reducing disturbance torque of a spacecraft is disclosed. The spacecraft revolves around a celestial body surrounded by an atmosphere. The control system includes processors in electronic communication with one or more actuators and a memory. The memory stores data into a database and program code that, when executed by the one or more processors, causes the control system to instruct the spacecraft to enter a safing mode. In response to entering the safing mode, the control system instructs the one or more actuators to align a principal axis of the spacecraft with a vector that is normal to the orbit around the celestial body. The control system also instructs the actuators to rotate the spacecraft about the principal axis, where a rotational orientation of the spacecraft relative to the celestial body is shifted by about one-half a rotation about the principal axis.

First claim

What is claimed is:

1. A control system for a spacecraft, the control system comprising:
one or more actuators;
one or more processors in electronic communication with the one or more actuators; and
a memory coupled to the one or more processors, the memory storing data into a database and program code that, when executed by the one or more processors, causes the control system to:
instruct the spacecraft to enter a safing mode, wherein the spacecraft revolves in an orbit around a celestial body having an atmosphere;
in response to entering the safing mode, instruct the one or more actuators to substantially align a principal axis of the spacecraft with a vector that is normal to the orbit around the celestial body;
instruct the one or more actuators to rotate the spacecraft about the principal axis, wherein a rotational orientation of the spacecraft relative to the celestial body is shifted by about one-half a rotation about the principal axis each time the spacecraft completes the orbit around the celestial body; and
instruct the one or more actuators to rotate the spacecraft a predetermined number of rotations about the principal axis at a constant rate as the spacecraft completes a single orbit around the celestial body, and wherein the predetermined number of rotations per orbit is determined by:
N+½

wherein a value N represents a positive integer including zero.

2. The control system of claim 1 , wherein the value N is determined based on one or more characteristics of the spacecraft that include: thermal characteristics of the spacecraft based on proximity to a source of heat, a solar wing angle, a rate limit of the spacecraft, a momentum limit of the spacecraft, and a structural rate limit of the spacecraft.

3. The control system of claim 1 , further comprising an antenna in electronic communication with the one or more processors, wherein the antenna is in wireless communication with a ground control system.

4. The control system of claim 3 , wherein the ground control system is located upon Earth.

5. The control system of claim 1 , further comprising a plurality of actuators, wherein a different actuator aligns the principal axis of the spacecraft with the vector that is normal to the orbit around the celestial body when compared to an actuator that rotates the spacecraft about the principal axis.

6. The control system of claim 1 , wherein the spacecraft enters the safing mode in response to determining one or more pre-defined spacecraft safing criteria are met.

7. A spacecraft, comprising:
a main body defining a principal axis;
one or more actuators;
one or more processors in electronic communication with the one or more actuators; and
a memory coupled to the one or more processors, the memory storing data into a database and program code that, when executed by the one or more processors, causes the spacecraft to:
instruct the spacecraft to enter a safing mode, wherein the spacecraft revolves in an orbit around a celestial body having an atmosphere;
in response to entering the safing mode, instruct the one or more actuators to substantially align the principal axis of the spacecraft with a vector that is normal to the orbit around the celestial body;
instruct the one or more actuators to rotate the spacecraft about the principal axis, wherein a rotational orientation of the spacecraft relative to the celestial body is shifted by about one-half a rotation about the principal axis each time the spacecraft completes the orbit around the celestial body; and
instruct the one or more actuators to rotate the spacecraft a predetermined number of rotations about the principal axis at a constant rate as the spacecraft completes a single orbit around the celestial body, wherein the predetermined number of rotations per orbit is determined by:
N+½

wherein a value N represents a positive integer including zero.

8. The spacecraft of claim 7 , wherein the value N is determined based on one or more characteristics of the spacecraft that include: thermal characteristics of the spacecraft based on proximity to a source of heat, a solar wing angle, a rate limit of the spacecraft, a momentum limit of the spacecraft, and a structural rate limit of the spacecraft.

9. The spacecraft of claim 7 , further comprising an antenna in electronic communication with the one or more processors, wherein the antenna is in wireless communication with a ground control system.

10. The spacecraft of claim 9 , wherein the ground control system is located upon Earth.

11. The spacecraft of claim 7 , wherein the spacecraft further comprises two or more solar wings, and wherein the two or more solar wings are substantially aligned with the principal axis of the main body of the spacecraft.

12. The spacecraft of claim 7 , wherein the spacecraft further comprises one or more electrical devices configured to generate and store electrical power, and wherein the one or more electrical devices include at least one of solar panels, radioisotope thermoelectric generators, batteries, capacitor banks, and heat engines.

13. The spacecraft of claim 7 , wherein the one or more actuators include at least one of a control moment gyroscope, a reaction wheel, thrusters, and magnetic torque rods.

14. The spacecraft of claim 7 , further comprising a plurality of actuators, wherein a different actuator aligns the principal axis of the spacecraft with the vector that is normal to the orbit around the celestial body when compared to an actuator that rotates the spacecraft about the principal axis.

15. The spacecraft of claim 7 , wherein the spacecraft enters the safing mode in response to determining one or more pre-defined spacecraft safing criteria are met.

16. A method for reducing disturbance torques experienced by a spacecraft, the method comprising:
instructing the spacecraft to enter a safing mode by a computer, wherein the spacecraft revolves in an orbit around a celestial body surrounded by an atmosphere;
in response to entering the safing mode, instructing, by the computer, one or more actuators of the spacecraft to substantially align a principal axis of the spacecraft with a vector that is normal to the orbit around the celestial body;
instructing the one or more actuators to rotate the spacecraft about the principal axis, wherein a rotational orientation of the spacecraft relative to the celestial body is shifted by about one-half a rotation about the principal axis each time the spacecraft completes the orbit around the celestial body;
instructing the one or more actuators to rotate the spacecraft a predetermined number of rotations about the principal axis at a constant rate as the spacecraft completes a single orbit around the celestial body; and
determining the predetermined number of rotations per orbit, wherein the predetermined number of rotations per orbit is determined by:
N+½

wherein a value N represents a positive integer including zero.

17. The method of claim 16 , further comprising determining the value N based on one or more characteristics of the spacecraft that include: thermal characteristics of the spacecraft based on proximity to a source of heat, a solar wing angle, a rate limit of the spacecraft, a momentum limit of the spacecraft, and a structural rate limit of the spacecraft.

18. The method of claim 16 , wherein the spacecraft further comprises two or more solar wings, and wherein the two or more solar wings are substantially aligned with the principal axis of a main body of the spacecraft.

19. The method of claim 1

Assignees

• Boeing Co

Inventors

• Wasson Christopher James
• Lemke Gary E
• Mills John Preston Charles
• Cantu Cecilia G
• Lui Timothy S

Classifications

• B64G1/242

  Orbits and trajectories · CPC title

• B64G1/281

  Spin-stabilised spacecraft · CPC title

• B64G1/366

  using magnetometers · CPC title

• B64G1/244 Primary

  Spacecraft control systems · CPC title

• B64G1/26

  using jets · CPC title