WO2010117819A1 - Reaction sphere for spacecraft attitude control - Google Patents

Reaction sphere for spacecraft attitude control Download PDF

Info

Publication number
WO2010117819A1
WO2010117819A1 PCT/US2010/029283 US2010029283W WO2010117819A1 WO 2010117819 A1 WO2010117819 A1 WO 2010117819A1 US 2010029283 W US2010029283 W US 2010029283W WO 2010117819 A1 WO2010117819 A1 WO 2010117819A1
Authority
WO
WIPO (PCT)
Prior art keywords
stator
rotor
reaction wheel
spherical rotor
wheel assembly
Prior art date
Application number
PCT/US2010/029283
Other languages
French (fr)
Inventor
John Doty
Original Assignee
Noqsi Aerospace, Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Noqsi Aerospace, Ltd filed Critical Noqsi Aerospace, Ltd
Publication of WO2010117819A1 publication Critical patent/WO2010117819A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64G—COSMONAUTICS; VEHICLES OR EQUIPMENT THEREFOR
    • B64G1/00—Cosmonautic vehicles
    • B64G1/22—Parts of, or equipment specially adapted for fitting in or to, cosmonautic vehicles
    • B64G1/24—Guiding or controlling apparatus, e.g. for attitude control
    • B64G1/28—Guiding or controlling apparatus, e.g. for attitude control using inertia or gyro effect
    • B64G1/283—Guiding or controlling apparatus, e.g. for attitude control using inertia or gyro effect using reaction wheels

Definitions

  • This invention relates to the field of spacecraft control mechanisms.
  • Spacecraft such as satellites and other craft, are controlled by mechanisms such as attitude and momentum control systems. These systems typically use control moment gyroscopes and reaction wheel assemblies for positioning and rotation.
  • Reaction wheel assemblies are commonly used to provide attitude control.
  • Reaction Wheel Assemblies include a spinning rotor that exerts a relatively small torque along the spin axis as the rotor is caused to spin faster or slower.
  • the assemblies usually include a rotor, bearings and a motor.
  • the motor is able to vary the speed of the wheel of the rotor.
  • a momentum exchange occurs as the speed of the wheel is varied. This creates a torque on the spacecraft about the spin axis. This torque will cause movement of the craft in the opposite direction.
  • reaction wheel assemblies typically arrayed with several reaction assemblies to cause rotation in any direction.
  • a typical application uses at least three reaction wheels in order to apply torque to the craft in any direction.
  • the reaction wheel assemblies typically are mounted on gimbals and bearings to control the torque being generated and for positioning the reaction wheel assemblies.
  • the rotors are mounted on bearings. The use of the gimbals and bearings add friction to the system, thus increasing the power necessary to operate the assemblies as well as decreasing the precision of the operation of the of the assemblies.
  • the present invention provides a frictionless stator/rotor that drives the rotor in any axis, thus eliminating the need for multiple gimbaled reaction wheel assemblies.
  • An electromagnetic stator surrounds a spherical conductive rotor to provide rotation of the rotor in a frictionless environment, as well as allows the rotor to be driven in any axis.
  • the stator of a preferred embodiment of the present invention uses a plurality of pole pieces with wire windings.
  • the pole pieces are arranged to surround the spherical rotor.
  • the pole pieces are arranged to form the shape of a truncated icosahedron around the spherical rotor.
  • Pentagonal shaped openings are formed spaced about the stator to provide access to the rotor for such components as sensors, angular velocity sensors and a caging mechanism.
  • the spherical rotor in one embodiment, is a hollow copper sphere.
  • the electromagnetic stator suspends the spherical rotor without friction as well as drives the spherical rotor in any axis.
  • the frictionless stator/rotor replaces the need for gimbaled stators/rotors as well as the use of mechanical bearings.
  • the magnetic fields introduced for stationary attitude in microgravity are very small since the required suspension forces and control torque are small.
  • torque errors are very small unlike convention wheels and bearings where the minimum torque necessary are determined by friction.
  • Figure 1 is an illustration of a typical satellite with reaction wheel attitude control.
  • Figure 2 is an illustration of a typical reaction wheel attitude control with cylindrical bearings.
  • Figure 3 is a top view of an embodiment of the magnetically suspended spherical rotor.
  • Figure 4 is a side view of the embodiment of Figure 3.
  • Figure 5 is an illustration of the stator of a preferred embodiment.
  • Figure 6 is an illustration of the pole piece of the stator.
  • Figure 7 is an illustration of the pole piece with winding.
  • Figure 8 is an illustration of the stator/rotor.
  • a preferred embodiment of the present invention is discussed herein. It is to be expressly understood that the descriptive embodiments are provided herein for explanatory purposes only and are not meant to unduly limit the claimed inventions.
  • the exemplary embodiments describe the present invention in terms of a reaction wheel assembly for use in attitude control of spacecrafts. It is to be understood that the present invention is intended for use with any application where three dimensional movement of a rotatable object is necessary.
  • a critical component of the reaction wheel assembly is the bearing upon which the rotor wheel is mounted.
  • a typical spacecraft such as a satellite 10 includes a fly wheel assembly 20 having a rotor 22 that is mounted on bearings 30.
  • the bearings are cylindrical bearings that may or may not be magnetic bearings.
  • Non-magnetic bearings include friction that may affect the control. The friction at low speeds cause sticking of the rotor while at high rotational speeds introduce chatter into the system. Friction limits the precision of the attitude control.
  • Magnetic bearings eliminate much of the friction but still have issues that affect the size and precision of the attitude control.
  • the magnetic bearings currently in use still provide only movement about a single axis. This results in moment exchange and torque in only a single axis.
  • multiple reaction wheel assemblies are required oriented in different axes to enable attitude control in all directions.
  • the magnetic bearing 50 of a preferred embodiment uses a magnetically suspended spherical rotor as the attitude control device.
  • the rotor 52 of the bearing 50 is a spherical rotor that is permanently magnetized.
  • the spherical rotor may be magnetized by induction from the stator 60.
  • the stator 60 provides a magnetic field that not only suspends the spherical rotor between the stator poles but also drives the rotation of the stator.
  • a static field induced by the stator provides the suspension force for the rotor as well as magnetizing the rotor. This induction may require the rotor to rotate a minimum speed.
  • the suspension field may rotate with the rotor.
  • One possible suspension method is to use alternating current induction. Other types of induction methods may be used as well.
  • FIG. 3 One example of the spherical magnetic bearing rotor for a reaction wheel assembly is shown in Figures 3 and 4.
  • the spherical rotor 52 is surrounded by the opposing electromagnetic pole assemblies 62, 64, 66, 68, 70, 72 (not shown) of the stator 60.
  • the electromagnetic pole assemblies suspend the conductive rotor 52 in a non- rotating suspension field as well as providing a rotating field to drive the rotor.
  • the stator 100 includes, in this embodiment, twenty ferrite pole pieces 110. Each pole piece has a copper wire winding 120 about the pole 112.
  • the twenty pole pieces 110 are assembled together to form a truncated icosahedron 130 about the rotor 140.
  • Pentagonal openings 132 in the stator allow access to the rotor 140.
  • the rotor in this embodiment, is a hollow copper sphere 140.
  • the fully assembled rotor/stator assembly 100 includes position sensors, angular velocity sensors and a caging mechanism. These components will have access to the rotor through the twelve pentagonal openings 132.
  • the use of the spherical conductive rotor as well as the electromagnetic stator not only provides rotation of the rotor in a frictionless environment, but also allows the rotor to be driven in any axis. This eliminates the need for multiple reaction wheel assemblies that are only able to be drive about a single axis and also eliminates the use of gimbaled assemblies.

Abstract

An electromagnetic stator 130 surrounds a spherical conductive rotor 140 to provide rotation of the rotor in a frictionless environment, as well as allows the rotor 140 to be driven in any axis. This eliminates the need for multiple reaction wheel assemblies that are only able to be drive about a single axis and also eliminates the use of gimbaled assemblies.

Description

Reaction Sphere for Spacecraft Attitude Control
[001] Related Application: This application claims the benefit of provisional application 61164868, filed on March 30, 2009.
[002] Field of the Invention: This invention relates to the field of spacecraft control mechanisms.
Background of the Invention
[003] Spacecraft, such as satellites and other craft, are controlled by mechanisms such as attitude and momentum control systems. These systems typically use control moment gyroscopes and reaction wheel assemblies for positioning and rotation. Reaction wheel assemblies are commonly used to provide attitude control. Reaction Wheel Assemblies include a spinning rotor that exerts a relatively small torque along the spin axis as the rotor is caused to spin faster or slower. The assemblies usually include a rotor, bearings and a motor. The motor is able to vary the speed of the wheel of the rotor. A momentum exchange occurs as the speed of the wheel is varied. This creates a torque on the spacecraft about the spin axis. This torque will cause movement of the craft in the opposite direction. These assemblies are typically arrayed with several reaction assemblies to cause rotation in any direction. A typical application uses at least three reaction wheels in order to apply torque to the craft in any direction. [004] The reaction wheel assemblies typically are mounted on gimbals and bearings to control the torque being generated and for positioning the reaction wheel assemblies. The rotors are mounted on bearings. The use of the gimbals and bearings add friction to the system, thus increasing the power necessary to operate the assemblies as well as decreasing the precision of the operation of the of the assemblies.
Summary of the Invention
[005] The present invention provides a frictionless stator/rotor that drives the rotor in any axis, thus eliminating the need for multiple gimbaled reaction wheel assemblies. An electromagnetic stator surrounds a spherical conductive rotor to provide rotation of the rotor in a frictionless environment, as well as allows the rotor to be driven in any axis.
This eliminates the need for multiple reaction wheel assemblies that are only able to be drive about a single axis and also eliminates the use of gimbaled assemblies.
[006] The stator of a preferred embodiment of the present invention uses a plurality of pole pieces with wire windings. The pole pieces are arranged to surround the spherical rotor. In one embodiment, the pole pieces are arranged to form the shape of a truncated icosahedron around the spherical rotor. Pentagonal shaped openings are formed spaced about the stator to provide access to the rotor for such components as sensors, angular velocity sensors and a caging mechanism. The spherical rotor, in one embodiment, is a hollow copper sphere. The electromagnetic stator suspends the spherical rotor without friction as well as drives the spherical rotor in any axis.
[007] The frictionless stator/rotor replaces the need for gimbaled stators/rotors as well as the use of mechanical bearings. The magnetic fields introduced for stationary attitude in microgravity are very small since the required suspension forces and control torque are small. Thus, torque errors are very small unlike convention wheels and bearings where the minimum torque necessary are determined by friction.
[008] These and other features of the claimed inventions will be evident from the ensuing detailed description of preferred embodiments, from the claims and from the drawings.
Brief Description of the Drawings
[009] Figure 1 is an illustration of a typical satellite with reaction wheel attitude control.
[0010] Figure 2 is an illustration of a typical reaction wheel attitude control with cylindrical bearings.
[0011] Figure 3 is a top view of an embodiment of the magnetically suspended spherical rotor.
[0012] Figure 4 is a side view of the embodiment of Figure 3.
[0013] Figure 5 is an illustration of the stator of a preferred embodiment.
[0014] Figure 6 is an illustration of the pole piece of the stator.
[0015] Figure 7 is an illustration of the pole piece with winding.
[0016] Figure 8 is an illustration of the stator/rotor.
Detailed Description of Preferred Embodiments
[0017] A preferred embodiment of the present invention is discussed herein. It is to be expressly understood that the descriptive embodiments are provided herein for explanatory purposes only and are not meant to unduly limit the claimed inventions. The exemplary embodiments describe the present invention in terms of a reaction wheel assembly for use in attitude control of spacecrafts. It is to be understood that the present invention is intended for use with any application where three dimensional movement of a rotatable object is necessary.
[0018] A critical component of the reaction wheel assembly is the bearing upon which the rotor wheel is mounted. As shown in Figures 1 and 2, a typical spacecraft such as a satellite 10 includes a fly wheel assembly 20 having a rotor 22 that is mounted on bearings 30. The bearings are cylindrical bearings that may or may not be magnetic bearings. Non-magnetic bearings include friction that may affect the control. The friction at low speeds cause sticking of the rotor while at high rotational speeds introduce chatter into the system. Friction limits the precision of the attitude control. [0019] Magnetic bearings eliminate much of the friction but still have issues that affect the size and precision of the attitude control. The magnetic bearings currently in use still provide only movement about a single axis. This results in moment exchange and torque in only a single axis. Thus, multiple reaction wheel assemblies are required oriented in different axes to enable attitude control in all directions.
[0020] An embodiment of the present invention is illustrated in Figure 3. The magnetic bearing 50 of a preferred embodiment uses a magnetically suspended spherical rotor as the attitude control device. The rotor 52 of the bearing 50 is a spherical rotor that is permanently magnetized. Alternatively, the spherical rotor may be magnetized by induction from the stator 60.
[0021] The stator 60 provides a magnetic field that not only suspends the spherical rotor between the stator poles but also drives the rotation of the stator. A static field induced by the stator provides the suspension force for the rotor as well as magnetizing the rotor. This induction may require the rotor to rotate a minimum speed. [0022] If the rotor is permanently magnetized, then the suspension field may rotate with the rotor. One possible suspension method is to use alternating current induction. Other types of induction methods may be used as well.
[0023] One example of the spherical magnetic bearing rotor for a reaction wheel assembly is shown in Figures 3 and 4. The spherical rotor 52 is surrounded by the opposing electromagnetic pole assemblies 62, 64, 66, 68, 70, 72 (not shown) of the stator 60. The electromagnetic pole assemblies suspend the conductive rotor 52 in a non- rotating suspension field as well as providing a rotating field to drive the rotor. [0024] Another embodiment of the present invention is illustrated in Figures 5 - 8. The stator 100 includes, in this embodiment, twenty ferrite pole pieces 110. Each pole piece has a copper wire winding 120 about the pole 112. The twenty pole pieces 110 are assembled together to form a truncated icosahedron 130 about the rotor 140. Pentagonal openings 132 in the stator allow access to the rotor 140. The rotor, in this embodiment, is a hollow copper sphere 140. The fully assembled rotor/stator assembly 100 includes position sensors, angular velocity sensors and a caging mechanism. These components will have access to the rotor through the twelve pentagonal openings 132. [0025] The use of the spherical conductive rotor as well as the electromagnetic stator not only provides rotation of the rotor in a frictionless environment, but also allows the rotor to be driven in any axis. This eliminates the need for multiple reaction wheel assemblies that are only able to be drive about a single axis and also eliminates the use of gimbaled assemblies.
[0026] The magnetic fields introduced for stationary attitude in microgravity are very small since the required suspension forces and control torque are small. Thus, torque errors are very small unlike convention wheels and bearings where the minimum torque necessary are determined by friction.
[0027] These and other embodiments of the present invention are considered to be within the scope of the present invention.

Claims

Claims
What is claimed is:
[Claim 1 ] A reaction wheel assembly for attitude control of a spacecraft, said assembly comprising: a conductive spherical rotor; and a stator for electromagnetically driving the rotation of said spherical rotor about multiple axes.
[Claim 2] The reaction wheel assembly of claim 1 wherein said stator further includes: electromagnets suspending said spherical rotor.
[Claim 3] The reaction wheel assembly of claim 1 wherein said stator includes: a plurality of pole pieces arranged around said stator.
[Claim 4] The reaction wheel assembly of claim 1 wherein said stator includes: a plurality of pole pieces arranged around said stator in a truncated icosahedron.
[Claim 5] The reaction wheel assembly of claim 1 wherein said stator includes: a plurality of openings spaced about said stator for access to said spherical rotor.
[Claim 6] The reaction wheel assembly of claim 1 wherein said spherical rotor includes: a hollow copper sphere.
[Claim 7] A reaction wheel assembly for attitude control of a spacecraft, said assembly comprising: a conductive spherical rotor; and a stator for electromagnetically driving the rotation of said spherical rotor about multiple axes and for suspending said spherical rotor.
[Claim 8] The reaction wheel assembly of claim 7 wherein said stator further includes: electromagnets suspending said spherical rotor.
[Claim 9] The reaction wheel assembly of claim 7 wherein said stator includes: a plurality of pole pieces arranged around said stator.
[Claim 1 0] The reaction wheel assembly of claim 7 wherein said stator includes: a plurality of pole pieces arranged around said stator in a truncated icosahedron.
[Claim 1 1 ] The reaction wheel assembly of claim 7 wherein said stator includes: a plurality of openings spaced about said stator for access to said spherical rotor.
[Claim 1 2] The reaction wheel assembly of claim 7 wherein said spherical rotor includes: a hollow copper sphere.
[Claim 1 3] A reaction wheel assembly for attitude control of a spacecraft, said assembly comprising: a conductive hollow copper spherical rotor; a stator for electromagnetically driving the rotation of said spherical rotor about multiple axes and for suspending said spherical rotor; a plurality of pole pieces arranged around said stator in a truncated icosahedron; and a plurality of openings arranged around said stator to allow access to said spherical rotor.
PCT/US2010/029283 2009-03-30 2010-03-30 Reaction sphere for spacecraft attitude control WO2010117819A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US16486809P 2009-03-30 2009-03-30
US61/164,868 2009-03-30

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WO2010117819A1 true WO2010117819A1 (en) 2010-10-14

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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20140209751A1 (en) * 2013-01-31 2014-07-31 Northrop Grumman Systems Corporation Reaction sphere for stabilization and control in three axes
CN104143947A (en) * 2014-06-30 2014-11-12 中国空间技术研究院 Inductive counteractive momentum sphere system
CN105388903A (en) * 2015-11-30 2016-03-09 中国空间技术研究院 Quick assembly module momentum sphere attitude control actuator
CN105577035A (en) * 2016-02-18 2016-05-11 三峡大学 Suspension control method of space small magnet
CN105799952A (en) * 2016-04-29 2016-07-27 北京航空航天大学 Multi-freedom-degree momentum exchange type aerospace craft posture adjusting and executing mechanism
EP3144229A4 (en) * 2014-05-12 2018-01-17 Korea Aerospace Research Institute Sphere magnetic levitation system and method of operating sphere magnetic levitation system
CN109104125A (en) * 2018-07-02 2018-12-28 清华大学 A kind of air bearing momentum sphere system of induction type driving
CN109466801A (en) * 2018-11-20 2019-03-15 中国人民解放军战略支援部队航天工程大学 A kind of magnetic suspension multi-directional ball
CN109751993A (en) * 2019-03-20 2019-05-14 扬州大学 A kind of spherical spinner apparatus for detecting position and posture and its detection method based on Photoelectric Detection

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3056303A (en) * 1958-08-29 1962-10-02 Thompson Ramo Wooldridge Inc Hydraulically and spherically supported inertial reference
US3611815A (en) * 1969-12-24 1971-10-12 Us Navy Frictionless gyroscope

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3056303A (en) * 1958-08-29 1962-10-02 Thompson Ramo Wooldridge Inc Hydraulically and spherically supported inertial reference
US3611815A (en) * 1969-12-24 1971-10-12 Us Navy Frictionless gyroscope

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9475592B2 (en) * 2013-01-31 2016-10-25 Northrop Grumman Systems Corporation Reaction sphere for stabilization and control in three axes
US20140209751A1 (en) * 2013-01-31 2014-07-31 Northrop Grumman Systems Corporation Reaction sphere for stabilization and control in three axes
US10283009B2 (en) * 2014-05-12 2019-05-07 Korea Aerospace Research Institute Sphere magnetic levitation system and method of operating sphere magnetic levitation system
EP3144229A4 (en) * 2014-05-12 2018-01-17 Korea Aerospace Research Institute Sphere magnetic levitation system and method of operating sphere magnetic levitation system
CN104143947A (en) * 2014-06-30 2014-11-12 中国空间技术研究院 Inductive counteractive momentum sphere system
CN104143947B (en) * 2014-06-30 2016-09-21 中国空间技术研究院 A kind of vicarious retroaction momentum sphere system
CN105388903A (en) * 2015-11-30 2016-03-09 中国空间技术研究院 Quick assembly module momentum sphere attitude control actuator
CN105388903B (en) * 2015-11-30 2018-02-06 中国空间技术研究院 A kind of module momentum sphere attitude control actuator of quick poly- dress
CN105577035B (en) * 2016-02-18 2017-07-14 三峡大学 space small magnet suspension control method
CN105577035A (en) * 2016-02-18 2016-05-11 三峡大学 Suspension control method of space small magnet
CN105799952A (en) * 2016-04-29 2016-07-27 北京航空航天大学 Multi-freedom-degree momentum exchange type aerospace craft posture adjusting and executing mechanism
CN109104125A (en) * 2018-07-02 2018-12-28 清华大学 A kind of air bearing momentum sphere system of induction type driving
CN109104125B (en) * 2018-07-02 2019-10-25 清华大学 A kind of air bearing momentum sphere system of induction type driving
CN109466801A (en) * 2018-11-20 2019-03-15 中国人民解放军战略支援部队航天工程大学 A kind of magnetic suspension multi-directional ball
CN109751993A (en) * 2019-03-20 2019-05-14 扬州大学 A kind of spherical spinner apparatus for detecting position and posture and its detection method based on Photoelectric Detection
CN109751993B (en) * 2019-03-20 2023-09-01 扬州大学 Spherical rotor pose detection device based on photoelectric detection and detection method thereof

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