United States Patent
`
`[19]
`
`[11] Patent Number:
`
`5,749,545
`
`Gnatjuk
`
`[45] Date of Patent:
`
`May 12, 1998
`
`US005749545A
`
`[54] AUTONOMOUS ON-BOARD SATELLITE
`CONTROL SYSTEM
`
`[76]
`
`Inventor: Sevastian Dmitrievich Gnatjuk. ul.
`Engelsa. 26-42. g.Khimki Moskovskoi
`obl.. Russian Federation
`
`[21] Appl. No.:
`
`505,262
`
`[22]
`
`PCI‘ Filed:
`
`Nov. 10, 1993
`
`[86]
`
`PCT No.:
`
`PCT/RU93/00262
`
`§ 371 Date:
`
`Aug. 23, 1995
`
`§ 102(c) Date: Aug. 23, 1995
`
`[87] PCT Pub. No.: WO94/18073
`
`PCT Pub. Date: Aug. 18, 1994
`
`Foreign Application Priority Data
`[30]
`Feb. 9, 1993
`[RU]
`Russian Federation ............. 93007754
`
`Int. 01.6 ....................................................... B64G 1/24
`[51]
`[52] US. Cl. .............................. 244/164
`
`
`. .................... 244/164—171
`[58] Field of Search
`
`[56]
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`5,108,050
`5,204,818
`5,277,385
`5.452.869
`5,508,932
`
`4/1992 Maute ..................................... 244/171
`4/1993 Landecker ......
`. 244/171
`1/1994 Flament ...................... 244/171
`
`..... 244/171
`9/1995 Basutliakur et a1.
`.......................... 244/171
`4/1996 Achkar et a1.
`
`FOREIGN PATENT DOCUMENTS
`
`263565
`
`10l1988
`
`France .
`
`OTHER PUBLICATIONS
`
`“Autonomous On—Board Orbit Determination Systems"
`Astrodynamics Conference. Aug. 20—22. 1984. Seattle. WA.
`
`Attorney, Agent, or Finn—Collard & Roe. PC.
`
`[57]
`
`ABSTRACT
`
`An autonomous omboard satellite control system is to
`achieve autonomous orientation control and autonomous
`determination of the satellite’s altitude and location in
`
`relation to the Earth‘s longitude and latitude grid. This is
`done with the aid of the following elements: an Earth sensor
`(1). a Pole—star sensor (2). a computer (4). a timing device
`(6) and actuator units (7). The system also includes a
`navigational star sensor (3) and a storage device (5). while
`the computer is designed so as to facilitate supplementary
`determinations. The orientation of the satellite is controlled
`
`by superimposing the general sensory plane (16) of the
`sensors (1 and 2) with the plane of the angle “center of
`Earth—satellite—Pole star” which defines latitude. The
`
`geovertical (11) rotates about a line to the Pole star (12) as
`the satellite (8) moves in its orbit (9) and this is equivalent
`to the revolution of the stars in the field of vision of the
`
`sensors (2 and 3). The rotation of the plan containing the
`lines to the stars (12 and 18) is measured in relation to a
`reference line (19) whose longitude and angular parameter
`(“B”) are kept in the storage device (5). Inertial longitude is
`calculated as the sum of the angle of measurement and the
`right ascension of the Pole star as the base longitude and is
`converted to the geocentric longitude. The altitude of the
`plan (16) to the latitudinal plane is calculated as the product
`of the polar distance of the Pole star and the sine of the angle
`of measurement. while its development (7) when in mis-
`alignment with the longitudinal axis (17) is calculated as the
`product of the angular dimension of the Earth’s radius. the
`sine of the angle is equal to the difierence in longitudes of
`a target point (20) and the point below the satellite and the
`cosine of the latitude angle.
`
`Primary Examiner—Galen L. Barefoot
`
`4 Claims, 3 Drawing Sheets
`
`
`
`
`
`Page 1 of 9
`
`SAMSUNG EXHIBIT 1010
`
`Page 1 of 9
`
`SAMSUNG EXHIBIT 1010
`
`

`

`US. Patent
`
`May 12, 1998
`
`Sheet 1 of 3
`
`5,749,545
`
`
`
`Page 2 of 9
`
`Page 2 of 9
`
`

`

`US. Patent
`
`May 12, 1998
`
`Sheet 2 of 3
`
`5,749,545
`
`
`
`Page 3 of 9
`
`Page 3 of 9
`
`

`

`US. Patent
`
`May 12, 1998
`
`Sheet 3 of 3
`
`5,749,545
`
`
`
`Fig. 7
`
`
`
`Fig. 8
`
`Page 4 of 9
`
`Page 4 of 9
`
`

`

`5.749.545
`
`1
`AUTONOMOUS ON-BOARD SATELLITE
`CONTROL SYSTEM
`
`Invention relates to astronavigation and satellite angular
`orientation control and is designed for using at autono-
`mously functioning satellite. Satellite. moving in three—
`dimensional space has six degrees of freedom In these
`environment satellite guide control is performed by naviga-
`tion and orientation system with the determination of three
`coordinates of location point: flight longitude. latitude and
`altitude and three angular orientation coordinates: pitch. roll
`and yaw.
`Active control orientation system of the geostationary
`satellite. being foreseen as analog.
`is known.(patent of
`France N 2637565. 1988).
`Mentioned orientation control system of the satellite is
`characterised by the following. System includes the Earth
`sensor. Sun sensors. sensor of the Pole star. processing and
`calculation units. drive motors. System provides three-axis
`satellite stabilization: east-west. north-south and geocentric.
`The following sensors are used while orientation control:
`pitch and roll: the Earth sensor;
`yaw: star sensor.
`These difierent sensors give the output signals. going into
`data processing networks. that are designed for correction
`manoeuvres amplitude determination according to this data;
`manoeuvres are executed by drivers of any known corre-
`sponding type (reactive flywheels. inertial flywheels and
`nozzles). Three satellite orientation angles. including yaw.
`are being constantly controlled in the working mode.
`Errors of the Earth sensor could be used for pitch and roll
`control without preliminary processing. Angular deviations.
`corresponding to pitch and roll channels during measure-
`ments by the Earth sensor are considered to be equal. System
`is characterised also by the fact.that in its composition there
`is a unit. containing the Pole star location evolution model.
`and this unit is connected with the telemetry unit. Hence. this
`model parameters are being renewed periodically. basing on
`the information. receiving from the Earth. In order to control
`yaw angle. it is necessary to execute the following opera-
`tions:
`
`basing at the ephemerids. processed by the mentioned
`unit. satellite location in the inertial coordinate system
`is calculated;
`after that. with the help of the same unit. theoretical
`coordinates of the Pole star in the star sensor field of
`view are to be calculated. while this is assumed. that the
`satellite has ideal orientation (pitch. yaw and roll are
`equal to zero).
`yaw error signal is calculated in the processing network.
`that is equal to the difierence of the Pole star location
`coordinates in the two-dimensional field of View. and
`basing on this error. yaw control amplitude is to be
`calculated in order to delete having shift.
`Mentioned system has the following. similar to invention.
`indications while the working mode providing:
`analogous devices are being used in the system: the Earth
`sensor. sensor of the Pole star. computer. actuator
`organs;
`
`orientation control on pitch and roll channels is provided
`with the help of the Earth sensor. on yaw channel—by
`star sensor. Foreseen as analog. mentioned system has
`the following demerits in the satellite angular position
`determining relatively to north—south axis (the Earth
`latitude plane):
`system is complicated by using of the unit. containing
`the Pole star position evolution model;
`
`10
`
`15
`
`20
`
`25
`
`3O
`
`35
`
`45
`
`50
`
`55
`
`65
`
`2
`system for renewing of the mentioned model
`parameters. depends on data. receiving from the
`Earth;
`system needs in performing of a row of calculation
`operations in order to calculate the difference
`between real and theoretical Pole star position coor-
`dinates in the star sensor field of View.
`Autonomous on-board system of orbit determination
`(article “Autonomous on-board orbit determination
`systems”. Astrodynamics Conference. Aug. 20—22. 1984.
`Seattle. Wash). being foreseen as a prototype. is known.
`Mentioned system includes the Earth sensor. Sun sensors.
`the Pole star sensor.computer. mass memory device. actuator
`organs. The Earth sensor is pointed into nadir and it forms
`errors on pitch and roll for orientation control systemthat
`keeps this direction in the limits of the central zone of
`non-sensitivity. Error signals are proportional to the Earth
`angular deviations from sensor line of sight on two across
`directions. Angle between the Earth sensor line of sight and
`the Sun sensor line of sight directions is measured by
`potenciometrical sensor of the panel drive-motor. installed
`on the panel. Angle “the Sun—object—the Earth" is the best
`observation for orbit determination. Information about the
`Sun location relatively to the Earth is taken from a file with
`ephemerides.
`The Sun ephemerides are put into the computer as a
`complicated time functions. If the Sun is in the satellite
`orbital plane.
`then angle “the Sun—object—the Earth”
`directly characterizes true inertional longitude of the satel-
`lite. If the Sun is not in the satellite orbital plane. measure-
`ment contains some information about orbit
`inclination
`components. Best evaluation conditions of the orbit incli-
`nation vector correspond to maximal Sun declination. the
`worst—to zero. If the Sun declination equal to zero.orbit
`inclination vector components are not observed In the case.
`if the angle “the Pole star—object—the Earth” is measured
`additionally. these components could be observed indepen-
`dently of the “light source” declination. In the case of
`determining according to the Pole star. it is considered. that
`additional measurements of “the Pole star—object—the
`Earth” angle are executed with the same frequency (1/30
`min). as “the Sun—object—the Earth" base angle measure-
`ments. Integrated data. based on both measurements
`sequence. mattes errors to be observing. Mentioned mea-
`surements are referenced in time Information on a present
`satellite location could be received from the equations of
`satellite moving. Integration of motion equations is per-
`formed with the fixed pitch. equal to 30 minutes. 30 minutes
`interval was chosen from the nominal system state correc-
`tion that is performed every 30 minutes.
`Mentioned system has the following. similar to invention
`indications:
`
`analogous devices are being used in the system. such as:
`the Earth sensor. the Pole star sensor. computer. storage
`device. timing device. actuator units;
`determination of satellite latitude is performed by “the
`Earth centre—satellite—the Pole star" angle measure—
`ment;
`
`orientation control on pitch and roll channels is provided
`by the Earth sensor. on yaw channel—it is presumed
`the Pole star sensor using.
`Foreseen as a prototype. mentioned system has the fol—
`lowing disadvantages in satellite location parameters deter—
`mination:
`
`Sun navigation reference point ephemerides are being
`input as a complicated functions of time;
`navigation measurements could not be performed con-
`tinuously due to periodically satellite shadowing by the
`Earth shadow;
`
`Page 5 of 9
`
`Page 5 of 9
`
`

`

`3
`
`5.749.545
`
`4
`
`direct determining of the satellite inertial longitude is
`possible only in one case. when angular misalignment
`of “the Sun—object—the Earth” angle and orbit planes
`is absent.
`In all other cases additional “the Earth
`centre—satellite—the Polar star” angle measurements
`and additional calculations are necessary.
`It should be noted. that mentioned system. similar to
`mentioned above analog. needs to correspond to the cycle of
`preliminary calculations in order to calculate diiference of
`real and theoretical Pole star coordinates in the star sensor
`field of view.
`
`An object is to create the satellite on-board guide control
`system. that could provide orientation autonomous control
`and antonomous determination of the satellite angular loca-
`tion relatively to the Earth’s latitude-longitude network. by:
`creation of the joint plane of sensitivity of the system
`sensors;
`
`10
`
`15
`
`combining of this plane with such an external plane.
`rotation of which in the inertial space occurs through
`orbital movement;
`
`20
`
`measurement of the mentioned turning by input into the
`system sensor;
`calculation by definite way the read-out base of turning.
`and base parameters containing in storage device.
`including into the system;
`calculation of inertial longitude as a sum of measured
`rotation angle and base longitude. and also satellite
`angular position according to function of inertial lon-
`gitude and overturn of the system sensors general plane
`of sensitivity relatively to the satellite structure. per—
`formed by computer with the possibility of determina-
`tion of the mentioned parameters. The system being
`used. contains the Earth sensor. the Pole star sensor.
`computer. timing device and actuator units. with the
`help of which control of angular orientation and deter-
`mination of location point latitude is performed. and in
`which computer is designed with the possibility of
`additional determinations. and in the composition of
`which there are navigational star sensor. storage device
`and their outputs are connected with the corresponding
`inputs of computer. Orientation control is being per-
`formed While combining of the Earth and the Pole star
`sensors general sensitivity plane. containing the satel-
`lite longitudinal axis. with the plane “the Earth
`centre—satellite—the Pole star” at the base of mea-
`sured angular misalignments in pitch. roll and yaw
`channels and formed corresponding conu'ol signals.
`While this. computer determines satellite location point
`inertial longitude. according to azimuth rotation angle
`in the field of view of star sensors. chosen navigation
`star around direction “satellite—the Pole star” rela—
`tively to the read—out base and taking into account
`inertial longitude of this base. parameters of which are
`kept is a storage advice. Read-out base. as a plane.
`containing in the corresponding field of View directions
`“satellite—the Pole star” and “satellite—navigation
`star”. characterizing by inertial longitude. that is equal
`to the Pole star right ascention. is overturned relatively
`to general sensitivity plane of the Earth and the Pole
`star sensors to an angle. that is equal to the angle
`between the plane. containing directions “the Earth
`centre—the Pole star". “the Earth centre—the Pole of
`the World" and “the Earth centre—the Pole star” and
`“the Earth centre-navigational star".
`Computer also determines angular position of the general
`sensitivity plane of the Earth and the Pole stair sensors
`
`Page 6 of 9
`
`relatively to the Earth latitude plane according to inertial
`longitude function. and its overturn relatively to satellite
`structure under the angular misalignment of geocentric
`vertical and the satellite longitude axis. pointed onto the
`target paint. determines as an angle. that is equal to those
`misalignment component. which depends on the difference
`of target and undersatellite points and the Earth angular
`dimension.
`One of the characterized features of proposed set of
`devices. including orientation control system. and naviga-
`tion control system. is the different use of the star sensors:
`one of the sensors is used inside the navigation circuit. and
`the other in the navigation circuit and in orientation circuit
`as well; the second feature—star positions. coordinated on
`two sensor’s axes. are used for azitmuth turning of the plane.
`containing directions onto the stars. Independence of the
`system in the angular orientation control mode is being
`achieved due to control performing under keeping the direc—
`tions to the Pole star and the Earth centre in one general
`sensory sensitivity plane. Under the conditions. when there
`is known angular misalignment between directions to the
`Pole of the World and to the Pole star in 48 angular minutes.
`determining of the external coordinate system (angular
`position of the satellite relatively to the north-south axis)
`according to the traditional experience is being previous to
`yaw orientation control.
`Original. in compareness with this experience. is the other
`sequence. when yaw control is being previous to the satellite
`angular position determination relatively to the Earth lati-
`tude plane. and it is a device for such determination.
`Depending on type of using orbits. on duration of the
`working stage and its location. angle between directions
`“satellite—the Earth centre” and “satellite—the Pole star”
`could change in a wide range.
`Keeping directions to the Pole star and to the Earth centre
`in one general plane of the Earth and the Pole star sensors
`causes oscillation of this plane relatively north—south axis
`(relatively to the Earth latitude plane) with the amplitude at
`a stationary orbit :48 arc. minutes in the day cycle.
`Current angular position of the satellite relatively to
`north—south axis depends on current inertial longitude of the
`satellite.
`While the satellite longitude changing during the orbital
`motion relatively the base value. for example. on 6 h. 12 h
`or 18 h. amplitude of the angular oscillation will be -48. 0.
`+48 arc. minutes correspondingly.
`In the common case. necessary angular position is being
`determined by multiplication of the Pole star polar distance
`onto the sine of the angle. value of which is equal to the
`difierence of the values of inertial longitude and the Pole star
`right ascention.
`Hence.
`the analogous satellite disadvantages are cor-
`rected.
`
`25
`
`30
`
`35
`
`4O
`
`45
`
`SO
`
`55
`
`65
`
`Due to proposed orientation control on yaw channel.
`geocentric vertical is projected onto the sky sphere. forming
`“vertical” (circle line in projection).
`Character feature of this “vertical” is its rotation around
`the direction onto the Pole star. due to the orbital movement.
`that in the satellite connected coordinate system is equiva-
`lent to the star field rotation around it.
`This rotation. being the source of navigational
`information. is measured by the input into the system sensor.
`In this case. the prototype disadvantages are taken out. that
`are usual while the Sun navigation. and that could be
`explained by the known angular misalignment of the eclipce
`and equator planes. by the periodical shadowing of the
`stationary satellite by the Earth shadow and by complication
`of the Sun ephemerides input.
`
`Page 6 of 9
`
`

`

`5
`
`5.749.545
`
`6
`out base. “Y’—angular misalignment of the geocentric ver-
`tical and longitudinal axis.
`At FIG. 5 view from the side of the Pole of the World is
`shown with the conventional picture of a map with three
`stars of North Polar row (including the Pole star). illustrating
`the determination of inertial longitude readout base. where
`21—map of the stars of North Polar row.
`FIG. 6 shows spherical triangle. necessary for determi-
`nation of the readout base angular parameter. where “B”—
`desired angle. “A”—angle. vertex of which is the Pole of the
`World. and which is equal to the difference of the right
`ascentions of navigational and the Pole stars. measured in
`degrees.
`“C”—angle. vertex of which is navigational star.
`“c”—polar distance of the Pole star.
`“b”—polar distance of navigational star.
`At FIG. 7. position of the readout base relatively to
`satellite structure during angular misalignment of geocentric
`vertical and longitudinal axis. determined from the triangle.
`is shown. where 22—angular dimension of the Earth radius.
`“aft—angle. which is equal to the diflerence of the target
`and undersatellitc points longitude diiference.
`At FIG. 8 function of the Pole star polar distance angular
`dimension of the satellite location point inertial longitude is
`shown. where 23—polar distance of the Pole star (“c".
`“6”—angle. which is equal to the difierence of values of the
`current inertial longitude and the Pole star right ascention.
`The best variant of invention using is a guide control
`system of the satellite at a stationary orbit.
`At this orbit changing of the angle “the Earth cente—
`satellite—the Pole star”. determining latitude of location
`point. is going in not very large interval. that doesn't put
`additional requirements to sensor’s field of view dimen-
`sions. System uses: double—coordinate sensor of the Earth 1.
`wide field double-coordinate star sensor 2—3. computer 4.
`storage device 5. timing device 6. actuator units 7.
`Using of one sensor. working on the Pole and navigational
`stars. simplifies structural composition of the system. An
`external coordinate system. containing the Earth centre.
`satellite and the Pole star is used. and for the determination
`
`of it special software is not needed.
`While combining of this plane with the general sensitivity
`plane 16. geocentric vertical 11. while the satellite 8 moving
`along the orbit 9. is rotated around the direction onto the
`Pole star. that is equivalent to stars rotation in the sensor 2—3
`field of view. measuring this rotation.
`'Ihrn of the plane. containing directions to stars 12 and 18.
`is measured relatively readout base 19. longitude and pre-
`viously calculated according to definite methodics angular
`parameter “E". which are kept in the storage device. Inertial
`longitude is defined by sum of the measuring angle and the
`Pole star right ascention. as a base longitude. and transfers
`into geocentric by known method. Angular position of the
`general sensitivity plane to the Earth latitude plane. due to
`the Pole star 23 polar distance. is being determined by
`computer as multiplication of polar distance on “9" angle
`sine. value of which is equal to value difference of the
`current inertial longitude and the Pole star right ascention.
`Asimutal overturning of the general sensitivity plane rela-
`tively to the satellite structure under the target angular
`misalignment ‘Y’ of geocentric vertical and longitudinal
`axis 17. oriented on to the target point 20. is determined by
`the computer as multiplication of the Earth radius angular
`dimension 22 on “to” angle sine. that is equal to longitude
`difl‘erence of the target and undersattelite points. (and on
`cosine of latitude). Latitude component of the misalignment
`angle could be determined analogously. In addition. accord-
`
`IO
`
`15
`
`20
`
`25
`
`30
`
`35
`
`45
`
`50
`
`55
`
`65
`
`Position of previously chosen navigation and the Pole
`stars in the corresponding field of view like the position of
`the plane. containing directions “satellite-navigation star”
`and “satellite—the Pole star". is measured relatively “ver-
`tical” by an angle that characterizes the inertial longitude.
`Moment of turning. when “vertical” coincides with the
`plane. containing directions “the Earth centre—the Pole
`star” and “the Earth centre—the Pole of the World”. is rated.
`while the determination of the readout base. being charac—
`terized by the right ascent of the Pole star and the angle
`relatively to plane “vertical”. containing directions onto
`navigational and the Pole star. Spherical triangle is used for
`determination of the desired angle. vertexes of which are the
`Pole of the World. the Pole star and navigational star. Value
`of this angle could be determined from Neper equations:
`B+C
`
`T8
`
`2
`2
`905% 26,31 “,le
`
`’
`
`
`B—C
`2
`
`:3
`
`E+c
`2
`
`sm
`
`A
`= 6137
`
`as;
`
`,
`
`where :
`as u
`
`—is desired angle;
`“A”—angle. vertex of which is the Pole of the World. and
`which is equal to the difference of right ascentions of
`the Pole and navigational stars. measured in degrees;
`“C”—-angle. vertex of which is navigational star;
`“c”—polar distance of the Pole star;
`“b”-polar distance of navigational star.
`Hence. inertial longitude is determined by the sum of
`measured relatively to turning base navigational star and
`base longitude. Its transfening into geocentric is performed
`by timing device according to known methodics.
`Target misalignment of geocentric vertical and the satel-
`lite longitude axis. oriented to the target point. gives the
`overturn of the general sensory sensitivity plane relatively to
`satellite base.and as a result turning of the readout base. This
`overturn is equal to those misalignment component. which
`depends on the difference of target and undersatellite points
`and the Earth angular dimension. This component could be
`determined as multiplication of the Earth radius annular
`dimension on sine of the angle. equal
`to difference of
`mentioned longitudes. and on cosine of latitude. The com-
`ponent is changed with the latitude changing: at the latitude
`in 90 degrees. it is equal to zero.
`At FIG. 1. true simplified structure of the guide control
`system is shown. where l—the Earth sensor. 2—3—the Pole
`star and navigation star sensors. 4—computer. 5—storage
`device 6—tirning device. 7—actuator units.
`At FIG. 2 satellite. stabilized relatively to geocentric
`vertical and direction on to the Pole star.
`is shown
`schematically. where 8—satellite. 9—orbit. lO—the Earth.
`ll—geocentric vertical. 12—direction to the Pole star.
`13—direction to the Pole of the World
`
`At FIG. 3 “vertical” rotation 3 a plane. containing geo-
`centric vertical and the direction to the Pole star. due to the
`satellite orbital movement. is shown. where 14—the sky
`sphere. 15—“vertical”.
`At FIG. 4 determination of the satellite inertial longitude
`on. the angular position relatively to general sensory sensi-
`tivity plane of the Earth and Pole star sensors. in the plane
`containing directions to navigational and the Pole stars. and
`inertial
`longitude readout base are shown. where
`16—general sensory sensitivity plane. 17—satellite longi-
`tudinal axis. 18—direction to navigational star. 19—readout
`base. ZO—target point. “B”—angular parameter of the read-
`
`Page 7 of 9
`
`Page 7 of 9
`
`

`

`7
`
`8
`
`5 .749.545
`
`ing to the difference of the true revolution period and star
`days duration. necessary orbit correction ignition pulse
`could be determined. and while determination of the
`latitude. according to the angle “the Earth centre-—
`satellite—the Pole star".—to take into account correction.
`due to the Pole star polar distance. and value of which
`depends on inertial longitude of the location point. After
`checking of the on-board time scale with the general single
`scale. satellite is to be launched into the orbit and oriented
`by known programmed overturns to the Earth. After catch-
`ing the Earth by the field of view of the rigid reinforced
`on-board satellite sensor. geocentric vertical is being built.
`The sensor principle of work is based on the Earth infrared
`radiation.
`
`Data. necessary for measuring of the deviation angle of
`geocentric vertical from the sensitivity plane (plane of pitch
`and roll). is processed while observing the two diameterally-
`opposite points of the Earth infrared horizon by method of
`plane scanning of the Earth disc by moment field of view.
`Scanning mirror provides by electromechanical drive motor
`the oscillation movement of sensor field of view relatively to
`the Earth disc. With corresponding pitch on scanning angle.
`data pulses are being processed. which then should go to
`computer. Difference of the numbers of data pulses is the
`criteria of the sensitivity plane deviation angle of geocentric
`vertical direction. Receiving in the computer coming signals
`are processed by corresponding method and control function
`as a sum of signals. proportional to being controlled value.
`dilferential and integral of it. is formed. After that. corre-
`spondingly to control function. signals should be amplified
`and converted before going to the actuator units.
`After deviations executing on pitch and roll. catching of
`the Pole star by the field of view of rigid reinforced on board
`the satellite star sensor is performed. For measurements of
`star’s coordinates of the fixed brightness band. sensor with
`the corresponding field of view and photoreceiver of corre-
`sponding sensitivity is required. Sensor. corresponding to
`these requirement’s. and produced by the industry. is used.
`While the voltage is going. sensor. searching the stars. looks
`through all fields of View.
`Star images are projected by lens optical sensor system
`onto the photoreceiver. (a CCD type instrument). While
`searching. sensor detects stars. brightness of which exceeds
`the input. With the help of a special algorythm. choosing of
`the Pole and navigational stars is performed.
`After their detecting. sensor performs tracking and peri-
`odically calculates their angular positions. Measured in the
`sensor coordinate system. star coordinates are given to
`computer.
`In computer. control function on the Pole star keeps in the
`general sensory sensitivity plane while orientation control
`on yaw channel is formed. and desired. angles are deter-
`mined.
`I claim:
`1. Autonomous on-board satellite control system. com-
`Prisms
`an Earth sensor having an output. a Pole star sensor
`having an output. a computer having inputs which are
`connected with said output of said Earth sensor and
`said output of said Pole star sensor and which deter-
`mines angular misalignments between satellite internal
`building axes and external coordinate system axes. and
`forms control signals for supporting the input relative
`to location of said coordinate system axes;
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`45
`
`50
`
`55
`
`a timing device having an output which is connected with
`a computer input;
`actuator units having an input which is connected with a
`computer output:
`
`65
`
`a navigational star sensor and a storage device of inertial
`longitude readout base parameters. and said parameters
`include the Pole star right ascension and an angle
`relative to the Pole star. and an Earth sensor general
`sensitivity plane. that is equal to an angle between the
`plane. containing an axis connecting the Earth center
`with the Pole star and an axis connecting the Earth
`center with the Pole of the World;
`
`the plane. containing an axis connecting the Earth center
`with the Pole star and the Earth center with the navi—
`gational star:
`said computer making a satellite location point latitude
`determination on the angle of the Earth center to
`satellite to the Pole star and providing an angular
`orientation control for the yaw control:
`
`said computer measuring corresponding angular mis-
`alignments and forming control signals. during which.
`general sensitivity plane of the Earth and the Pole star
`sensors. containing satellite longitudinal axis is com-
`bined with the plane. containing the Earth center.
`satellite and the Pole star;
`
`said computer making a determination of satellite location
`point inertial longitude according to azimuth angle of
`chosen navigational star turning around the direction of
`satellite to the Pole star. to be counted in corresponding
`field of view from the base angular position of the
`plane. containing directions satellite to the navigational
`star and satellite to the Pole star. taking into account
`inertial longitude of this readout base. such that outputs
`of the navigational star sensor and the storage device
`are connected with the corresponding computer inputs;
`and
`
`said computer calculating a correction. determined as a
`multiplication of polar distance of the Pole star onto
`cosine of the angle. equal to the difference of the value
`of current inertial longitude and right ascension of the
`Pole star.
`
`2. System according to claim 1.
`wherein the Earth sensor and the Pole star sensor general
`sensitivity plane is located within an angle to the
`satellite longitudinal axis. directed to a target point;
`said computer determining said angle by multiplication of
`Earth radius angular dimension onto the sine of said
`angle. equal to the target and undersatellite points
`longitude diiference. and on cosine of the latitude
`angle; and
`said computer determining of geocentric longitude as the
`sum of inertial longitude and multiplication of the Earth
`revolution velocity onto on-board star time.
`3. System according to claim 1.
`wherein said computer determining the Earth and the Pole
`star sensors general sensitivity plane angular position
`relative to the Earth latitude plane by multiplication of
`the Pole star polar distance onto the sine of an angle.
`equal to difference of values of the current inertial
`longitude and the Pole star right ascension.
`4. System according to claim 1.
`wherein the joint sensitivity plane of the Earth sensor and
`the Pole star sensor is placed at an angle to the
`longitudinal satellite axis. and directed to the target
`point;
`said computer determining the longitudinal component of
`the angle between direction to undersatellite and direc-
`tion to target points as a multiplication of the Earth
`radius angular dimension onto sine of an angle. which
`
`Page 8 of 9
`
`Page 8 of 9
`
`

`

`9
`
`10
`
`5 ,749.545
`
`is equal to the difierence of longitudes of target and
`undersatcllite points. and onto cosine of the target point
`latitude angle; and
`said computer determining latitude component as a mul-
`tiplication of the Earth radius angular dimension onto
`
`sine of an angle. which is equal to the difference in
`latitude of the target and the latitude of the undersat-
`ellite points.
`
`*
`
`*
`
`*
`
`*
`
`*
`
`Page 9 of 9
`
`Page 9 of 9
`
`