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
  • B64G1/286—Guiding or controlling apparatus, e.g. for attitude control using inertia or gyro effect using control momentum gyroscopes (CMGs)
• • 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
  • B64G1/244—Spacecraft control systems
• • 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
• • 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
  • B64G1/285—Guiding or controlling apparatus, e.g. for attitude control using inertia or gyro effect using momentum wheels
• • 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
  • B64G1/36—Guiding or controlling apparatus, e.g. for attitude control using sensors, e.g. sun-sensors, horizon sensors

Definitions

• the present invention relates to vehicle control and more particularly to attitude control apparatus for spacecraft. Yet more specifically, the present invention relates to a novel arrangement for reaction wheels (RW's), momentum wheels (MW's) and/or control moment gyros (CMG's) used to position a space vehicle and control its attitude.
• RW's reaction wheels
• MW's momentum wheels
• CMG's control moment gyros
• the prior CMG art requires a gimbal rate sensor or tachometer which when combined with other data can be used to derive an approximation of the torque being delivered to the spacecraft.
• the sensor its self induces higher frequency signals which results in added and undesirable vibrations being transmitted to the spacecraft.
• the prior CMG art uses ring like mounting structures which are bolted to a plate structure in the spacecraft. This primarily two- dimensional structure is structurally inefficient. Each unit delivers torque to the spacecraft as its single function, but the net effect cannot be measured directly and efficiently.
• the present invention is more of a three-dimensional system having somewhat equal dimensions in all three spatial axes.
• the present invention overcomes the problems of the prior art by providing an integrated single unitary structure containing multiple spinning bodies, the electronics to control them and the intelligence to interface with the spacecraft on the sub-system level. Repackaging the system into a single integrated unit allows the manufacturer to design a single and more efficient structure to house the inner gimbal assemblies of the RW's, MW's or CMG's. With CMG's the outer gimbal base ring as a separate part, can be eliminated and the lower number of electronic boxes can be reduced resulting in reduced weight and the number of connections to the vehicle further reduces weight and improves heat conduction transfer to the outer surfaces of the vehicle.
• the unit manufacturer now has to deal with a single momentum control unit and, on delivery, the unit will be able to be plugged in to reduce the contractor cost and improve the spacecraft manufacturing schedule.
• the total volume occupied by the unitary structures will be smaller than that of separate mounted units.
• the arrangement and other design changes enabled by the grouping together converts the result into a higher level system offering many advantages including, better performance, the ability to measure the performance more accurately and more directly, lower weight, lower power, a smaller package, and lower cost.
• Using common circuits within the system reduces the number of electronic components. The number and resulting weight of cables and connector is also be reduced.
• Figure 1 is one preferred embodiment of a unitary structure of the present invention housing a plurality of control moment gyros;
• Figure 2 is one preferred mounting structure attaching the unitary structure of
• Figure 3 is another preferred embodiment of the unitary structure of the present invention.
• a unitary moment control unit (MCU) 10 is shown containing four control moment gyros (CMG's) identified by reference numerals 12, 14, 16 and 18. While the structure of MCU 10 is shown as a symmetrical 14 sided structure, other configurations are possible and while CMG's are used for the preferred embodiment, other rotating mass members such as reaction wheels or momentum wheels may be used. It should also be understood, that while four CMG's have been shown, fewer may be used. Three CMGs are necessary for three axis control and the fourth CMG is for redundancy. Also more than four CMG's may be employed for fail safe and fail operational functions.
• An electronic package 20 having an input connection 22 and providing connection to each of the CMG's is shown by connectors
• CMG 12 is mounted to the MCU 10 by a mounting member 40 on one end and by an unseen centrally located mounting member in a manner to be described in connection with Figure 3.
• CMG 14 is mounted to the MCU 10 by a mounting member
• CMG 18 is mounted to the MCU 10 by a mounting member 44 on one end and by the unseen centrally located mounting member.
• CMG 16 is mounted similarly to the others by two unseen mounting members.
• the MCU is held in a rigid arrangement made up of a plurality of terminal members shown as spheres 50 and a plurality of elongated joining members 52.
• Electronics box 20 may be connected to one or more of the elongated members 52.
• the orientation of the CMG's is such that they do no lie on any axis in common.
• the torque imparted by the CMGs will be resolved into a three orthogonal axes arrangement by using vector addition of their individual torque's.
• the space craft to which the MCU is mounted as will be described in connection with Figure 2, will be oriented as desired. If an CMG fails, the fourth CMG may be used to supply any missing torque.
• the mounting of the MCU 10 to the spacecraft is important in order to impart the necessary torque and to minimize emitted vibration.
• the mounting should also be kinematic to minimize strain due to temperature changes This may be accomplished by a strut type element which has relatively high stiffness along its longitudinal axis and relatively low stiffness in the other axes.
• Co-pending application of David Osterberg entitled Load Isolator apparatus filed January 29, 1997 with serial number 08/790,647 and assigned to the assignee of the present invention describes a load isolator damper arrangement which may be used.
• the number of struts used to mount the MCU is also important.
• One of the most stable ways to mount a structure is by a hexapod arrangement also known as a Stewart Platform as will be described in connection with Figure 2.
• FIG 2 a small portion of the structure of Figure 1 is shown somewhat enlarged for clarity.
• Three mounting members 60, 62 and 64 which may be members such as shown as mounting members 40 of Figure 1, are shown joined by elongated joining members 66, 68 and 70 which may be a suitable three of the joining members 52 of Figure 1.
• a hexapod mounting consisting of six struts 72, 74, 76, 78, 80 and 82 are shown.
• Struts 72 and 74 each have one end connected to mounting member 60 while their other ends are pivotally connected to pivots 84 and 86 so as to be rotatable about axes 88 and 90 respectively.
• Struts 76 and 78 each have one end connected to mounting member 62 while their other ends are pivotally connected to pivots 94 and 96 so as to be rotatable about axes 98 and 100 respectively.
• Struts 80 and 82 each have one end connected to mounting member 64 while their other ends are pivotally connected to pivots 102 and 104 so as to be rotatable about axes 106 and 108 respectively.
• Pivots 84, 86, 94, 96, 102 and 104 are each connected to the spacecraft as shown by hatched lines 110.
• Struts 72, 74, 76, 78 and 80 are designed to include a predetermined desired amount of static stiffness and passive damping.
• the passive isolation system become a mechanical low pass filter which transmits desired torque's to the spacecraft while eliminating unwanted higher frequency vibrations. Furthermore, the passive isolation system reduces structural and bearing loads during launch, reduces weight and power consumption and allows the use of smaller bearings which emit less vibration and can be operated at higher speeds while providing longer life.
• each CMG can provide damping and a measure of vibration isolation.
• force sensors within the struts and feeding the information to a control system the precision of the torque transmitted can be improved.
• an actuator can be added to each strut to provide an active isolation control capability .This can be used to lower the frequency with which isolation and torque control can be provided.
• hexapod arrangement is preferable, there may be situations where it is more practical to use more mounting members. For example, if a rectangular package is used, and eight strut arrangement with two struts at each of four corners might be preferred.
• Figure 3 shows an octopod mounting arrangement
• a unitary momentum control unit 120 is shown with four CMG's 122, 124, 126 and 128 mounted therein.
• CMG 122 is mounted at one end to a mounting member 130 similar to the mounting arrangement of Figure 1.
• the other end of CMG 122 is mounted to a central mounting member 134 and the spinning mass therein (not seen) rotates about an axis 138.
• CMG 124 is mounted at one end to a mounting member 140 and the other end is mounted to the central mounting member 134 and its spinning mass (not seen) rotates about an axis 144.
• CMG 126 is mounted at one end to a mounting member 150 and the other end is mounted to the central mounting member 134 and its spinning mass (not seen) rotates about an axis 154.
• CMG 128 is mounted at one end to a mounting member 160 and the other end is mounted to the central mounting member 134 and its spinning mass (not seen) rotates about an axis 164.
• the structure of MCU 120 is otherwise like the structure of MCU 10 in figure 1 and will not be described further except to note that mounting members 130, 14, 150 and 160 are mounted to the spacecraft (shown by hash marks 170) by eight struts 172 with two at each corner.
• the struts 172 may be the same as described in connection with Figure 2.
• the electronics box 20 of Figure 1 has been omitted form Figure 3 for purposes of clarity. It is seen that the package comprising unitary MCU 10 is more spherical in general overall shape while the structure of the package of MCU 120 is more flat.
• the unitary structure is applicable to RW's and MW's as well as the CMG's used in the preferred embodiments. Accordingly, I do not wish to be limited to the specific structures used in connection with the preferred embodiments described herein.

Landscapes

• Engineering & Computer Science (AREA)
• Remote Sensing (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Radar, Positioning & Navigation (AREA)
• Aviation & Aerospace Engineering (AREA)
• Automation & Control Theory (AREA)
• Control Of Position, Course, Altitude, Or Attitude Of Moving Bodies (AREA)
• Vibration Prevention Devices (AREA)
• Gyroscopes (AREA)

Priority Applications (3)

Applications Claiming Priority (2)

Publications (2)

Family

ID=22489219

Family Applications (1)

Country Status (5)

Cited By (1)

Families Citing this family (19)

Family Cites Families (25)

• 1998
  • 1998-08-26 US US09/139,989 patent/US6340137B1/en not_active Expired - Lifetime
• 1999
  • 1999-08-05 DE DE69914205T patent/DE69914205T2/de not_active Expired - Lifetime
  • 1999-08-05 EP EP99960101A patent/EP1107852B1/en not_active Expired - Lifetime
  • 1999-08-05 JP JP2000567353A patent/JP4266520B2/ja not_active Expired - Fee Related
  • 1999-08-05 WO PCT/US1999/017764 patent/WO2000012269A2/en not_active Ceased

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