UNNAA
`~ U8005749545A
`
`[11] Patent Number:
`
`[45] Date of Patent:
`
`5,749,545
`May12, 1998
`
`Attorney, Agent, or Firm—Collard & Roe. PC.
`
`[57]
`
`ABSTRACT
`
`An autonomous on-board 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
`
`United States Patent 15
`Gnatjuk
`
`[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] PCT Filed:
`
`Nov. 10, 1993
`
`[86]
`
`PCT No.:
`
`PCT/RU93/00262
`
`§ 371 Date:
`
`Aug. 23, 1995
`
`§ 102(e) 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
`
`[SUP Unt, C1o cceescsesssssssesscscscccensessorsssanascess B64G 1/24
`[52] US. C1. oecesessscsssnsscenecenssceesscnssnsseneneccaensaceess 244/164
`
`
`[58] Field of Search ....
`saeseessensaeeseneneses 244/164—-171
`
`[56]
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`
`
`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
`5,108,050«=4/1992 Maite oo...eececcseessesersseaee race 244/171
`right ascension of the Pole star as the base longitude andis
`5,204,818
`4/1993 Landecker......
`. 244/171
`converted to the geocentric longitude. The altitude of the
`3,277,385
`1/1994 Flament
`.....ccecessesescnessseeerssees 244/171
`plan (16) to the latitudinal plane is calculated as the product
`5,452,869
`9/1995 Basuthakur et al.
`............serese 244/171
`5,508,932
`4/1996 Achkar et al.
`......scessesssersseee 244/171
`of the polar distance of the Pole star and the sine of the angle
`of measurement, while its development (y) 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 difference in longitudes of
`a target point (20) and the point below the satellite and the
`cosine of the latitude angle.
`
`FOREIGN PATENT DOCUMENTS
`
`263565
`
`10/1988
`
`France .
`
`OTHER PUBLICATIONS
`
`“Autonomous On-Board Orbit Determination Systems”
`Astrodynamics Conference, Aug. 20-22, 1984, Seattle, WA.
`
`Primary Examiner—Galen L. Barefoot
`
`4 Claims, 3 Drawing Sheets
`
`
`
`
`
`Page 1 of 9
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`SAMSUNG EXHIBIT 1010
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`Page 1 of 9
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`SAMSUNG EXHIBIT 1010
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`Sheet 1 of 3
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`May12, 1998
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`5,749,545
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`U.S. Patent
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`U.S. Patent
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`May 12, 1998
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`Sheet 2 of 3
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`5,749,545
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`Sheet 3 of 3
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`Fig. 7
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`May12, 1998
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`5,749,545
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`U.S. Patent
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`5,749,545
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`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 different 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 forpitch androll
`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.
`andthis unit is connected with the telemetry unit. Hence,this
`model parameters are being renewedperiodically, 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 areto 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 difference 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;
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`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
`(atticle “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 system.that
`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 sensorline 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 notin 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 (‘40
`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 disadvantagesin 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;
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`5.749.545
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`3
`direct determining of the satellite inertial longitude is
`possible only in one case. when angular misalignment
`of “the Sun—object—the Harth” angle andorbit 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. needsto correspondto the cycle of
`preliminary calculations in order to calculate difference of
`real and theoretical Pole star coordinates in the star sensor
`field of view.
`Anobject is to create the satellite on-board guide control
`system. that could provide orientation autonomous control
`and antonomousdetermination 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;
`combining of this plane with such an external plane.
`rotation of which in the inertial space occurs through
`orbital movement;
`measurementof 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
`andtheir 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 control signals.
`While this. computer determinessatellite 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 correspondingfield 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
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`20
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`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 onthe 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. whenthere
`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)
`accordingto the traditional experience is being previous to
`yaw orientation control.
`Original. in compareness with this experience,is the other
`sequence. when yaw controlis being previousto the satellite
`angular position determination relatively to the Earth lati-
`tude plane. andit 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 directionsto 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 currentinertial longitude of the
`satellite.
`While the satellite longitude changing during the orbital
`motion relatively the base value. for example, on 6h, 12h
`or 18 h, amplitude of the angular oscillation will be 48, 0.
`+48 arc. minutes correspondingly.
`In the commoncase. 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
`difference of the valuesof inertial longitude and the Pole star
`right ascention.
`Hence,
`the analogoussatellite disadvantages are cor-
`rected.
`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 aroundit.
`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 misalignmentof 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.
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`5.749,545
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`5
`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+
`se
`
`
`tg
`
`cos BES = cg A 00s BoeF
`
`+
`
`where:«ny
`—is desired angle;
`“A”—angle. vertex of whichis 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 transferring into geocentric is performed
`by timing device according to known methodics.
`Target misalignment of geocentric vertical and thesatel-
`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 readoutbase. This
`overturn is equal to those misalignment component, which
`dependson 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:atthe latitude
`in 90 degrees, it is equal to zero.
`At FIG. 1, true simplified structure of the guide control
`system is shown. where 1—the Earth sensor, 2—3—thePole
`star and navigation star sensors, 4—computer, 5—-storage
`device 6—timing 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, 10—the Earth,
`11—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 ofthe 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, 20—1target point, “B”—angular parameter of the read-
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`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 Worldis
`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—mapofthe 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 whichis 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,
`“w"—angle. which is equal to the difference of the target
`and undersatellite points longitude difference.
`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”.
`“@”—angle. which is equal to the difference 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 centre—
`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.
`Turn ofthe 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 “B”, 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 “8” 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 “@” angle sine, that is equal to longitude
`difference of the target and undersattelite points, (and on
`cosine of latitude). Latitude component of the misalignment
`angle could be determined analogously. In addition, accord-
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`5.749.545
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`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
`androll), is processed while observing the two diameterally-
`opposite points of the Earth infrared horizon by method of
`plane scanning of the Earth disc by momentfield of view.
`Scanning mirror provides by electromechanical drive motor
`the oscillation movementofsensorfield of view relatively to
`the Earth disc. With correspondingpitch 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 comingsignals
`are processed by corresponding methodandcontrol function
`as a sum ofsignals, proportional to being controlled value.
`differential 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 Polestar by the field of view ofrigid 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 keepsin 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-
`prising
`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 betweensatellite internal
`building axes and external coordinate system axes, and
`forms control signals for supporting the inputrelative
`to location of said coordinate system axes,
`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;
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`10
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`15
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`20
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`25
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`30
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`35
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`45
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`50
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`55
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`a navigational star sensor and a storage device ofinertial
`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 betweenthe
`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 determinationofsatellite location
`point inertial longitude according to azimuth angle of
`chosen navigational star turning aroundthe direction of
`satellite to the Pole star, to be counted in corresponding
`field of view from the base angular position of the
`plane, containing directionssatellite to the navigational
`star and satellite to the Pole star. taking into account
`inertial longitude of this readoutbase. 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 difference, and on cosine of the latitude
`angle; and
`said computer determining of geocentric longitude as the
`sum ofinertial 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 componentof
`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
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`is equal to the difference of longitudes of target and
`undersatellite points, and onto cosineof the target point
`latitude angle; and
`said computer determining latitude component as a mul-
`tiplication of the Earth radius angular dimension onto
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`10
`sine of an angle. which is equal to the difference in
`latitude of the target and the latitude of the undersat-
`ellite points.
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`x
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`ok ee F
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