CN115267854B - Advanced alignment method and device based on satellite trajectory prediction - Google Patents
Advanced alignment method and device based on satellite trajectory prediction Download PDFInfo
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- CN115267854B CN115267854B CN202211155382.6A CN202211155382A CN115267854B CN 115267854 B CN115267854 B CN 115267854B CN 202211155382 A CN202211155382 A CN 202211155382A CN 115267854 B CN115267854 B CN 115267854B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
- G01S19/38—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system
- G01S19/39—Determining a navigation solution using signals transmitted by a satellite radio beacon positioning system the satellite radio beacon positioning system transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
- G01S19/393—Trajectory determination or predictive tracking, e.g. Kalman filtering
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/11—Arrangements specific to free-space transmission, i.e. transmission through air or vacuum
- H04B10/118—Arrangements specific to free-space transmission, i.e. transmission through air or vacuum specially adapted for satellite communication
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/14—Relay systems
- H04B7/15—Active relay systems
- H04B7/185—Space-based or airborne stations; Stations for satellite systems
- H04B7/1851—Systems using a satellite or space-based relay
- H04B7/18515—Transmission equipment in satellites or space-based relays
Abstract
The invention provides a satellite trajectory prediction-based advanced alignment method and a satellite trajectory prediction-based advanced alignment device, which comprise the following steps: acquiring the miss distance of the light spot of the target satellite relative to the tracking visual axis and the tracking visual axis angle of the target satellite; calculating to obtain real space position information of the target satellite according to the tracking visual axis angle and the miss distance; performing prediction filtering processing on the target satellite according to the real space position information to obtain a speed prediction value of the target satellite at the next moment; and calculating to obtain an advanced alignment angle and a prediction direction according to the predicted speed value, and performing advanced alignment processing on the target satellite according to the advanced alignment angle and the prediction direction. According to the method, the real space position information is synthesized by tracking the visual axis angle and the miss distance, the obtained real space position information is more accurate due to the fact that the data accuracy and the real-time performance of the tracking visual axis angle and the miss distance are high, the advanced alignment angle and the predicted direction are obtained in a prediction filtering mode, and therefore the accuracy during advanced alignment is improved.
Description
Technical Field
The invention relates to the technical field of satellite communication, in particular to an advanced alignment method and device based on satellite trajectory prediction.
Background
The satellite communication system using laser as carrier has the characteristics of large bandwidth, high speed, strong confidentiality, no application of frequency spectrum, small terminal size, light weight, low power consumption and the like, and becomes a development trend of satellite communication. Because the laser communication system has a small beam divergence angle, a long communication distance and a high relative movement speed, the Acquisition, tracking and Pointing (ATP) technology of a light beam is one of the key technologies of satellite optical communication. The alignment technique mainly refers to advance alignment, i.e. a compensation technique for the position deviation of the limited light speed in the long-distance transmission. As shown in FIG. 1, two optical transceivers on satellites # 1 and #2Communication is carried out, the light beam emitted by the satellite # 2 optical transceiver B at p (k-1) reaches the satellite # 1 optical transceiver A after t, and the optical transceiver B moves to p (k); the light emitted by the optical transceiver A at t (k) reaches the optical transceiver B at time t, and the position of the optical transceiver B moves to p (k + 1). Therefore, the optical transceiver a needs to compensate the deviation caused by the position shift of p (k-1), p (k), and p (k + 1) on the basis of the tracking visual axis when emitting the light beam. Defining the included angle between the tracking visual axis and the emission visual axis of the optical transmitter and receiver A as an advanced alignment angle
Can be approximately expressed as
Wherein v is the relative movement speed in the direction perpendicular to the connecting line of the two communication ends, and C is the light speed.
It can be seen from the formula that the magnitude of the advance alignment angle is related to the relative motion velocity between the satellites. The range of advanced alignment angles between GEO-LEO (orbit height 500 km) is about
Increases as the track inclination increases; the advanced alignment angle of the deep space probe such as the Psyche asteroid probe of the NASA deep space project to the ground station can be maximally reached
。
The functional schematic diagram of the advance alignment in a typical optical transmitter and receiver is shown in fig. 2. The existing advanced alignment function realization method is mainly characterized in that a ground station or satellite-borne computing equipment calculates the advance angle of a link to be established according to ephemeris or GPS information, then the calculated result is converted into a control instruction, and an advanced alignment mechanism is driven through the control instruction to realize the advanced alignment of a transmitting visual axis. It can be seen that the advance alignment function is relatively independent in the optical transceiver control system, no light beam closed loop feedback amount exists, the method belongs to open loop control, and the acquisition of the advance angle completely depends on track data outside the optical transceiver. Orbit data is obtained by orbit prediction injection or satellite platform parameter broadcasting. One method for orbit prediction injection is to give the position and speed change data of a satellite at a specific time in the future by using an ephemeris, finish the advance angle of a payload device through ground calculation, and then upload and inject the advance angle into the payload; the other method is to directly inject orbit prediction data into the payload, and the advance angle is calculated in real time when the payload runs, wherein the advance angle has the advantages of being capable of compensating satellite orbit attitude errors and large in calculation amount. In addition, the satellite platform parameter broadcasting mode is that the satellite analyzes the current satellite position and speed through a GPS receiver, the measurement and control unit provides satellite attitude error data and broadcasts the satellite attitude error data to the optical terminal, and the optical terminal calculates the required advance angle through the appointed target satellite or ground station position. The method has the advantages that ground data is not needed to be uploaded and injected into orbit data, the satellite attitude error can be compensated in real time, and the defects that the calculation amount is large and a GPS receiver possibly has the problem of signal loss are overcome.
The prior optical transceiver advanced alignment angle obtaining process comprises the following steps: (1) Calculating a leading alignment angle vector based on the relative speed of the satellite in an inertial coordinate system, and expressing the vector by using a coordinate system in which the orbit prediction data is positioned; (2) converting the lead angle into a satellite loading equipment coordinate system; (3) Converting the lead angle from a satellite load equipment coordinate system to an optical transmitter and receiver visual axis coordinate system; (4) Calculating according to the optical path transformation matrix of the optical transceiver to obtain two-dimensional rotation quantity corresponding to the lead angle; (5) And driving the advance alignment mechanism to rotate according to the rotation quantity, so as to realize the advance alignment function.
It can be seen that the current advanced alignment method mainly depends on the real-time property of satellite orbit parameter injection or broadcast and the accuracy of transformation of each coordinate system. In the case that the satellite orbit parameters cannot be updated in time and the orbit measurement itself has errors, the acquisition of the advanced alignment angle becomes unreliable. Meanwhile, the attitude of a satellite platform where the optical transceiver is located drifts, the channel has refraction characteristics (such as atmospheric refraction between air-ground links), and the advanced alignment angle deviation can be increased by completely depending on orbit data.
Therefore, the prior art has defects and needs to be improved and developed.
Disclosure of Invention
The present invention provides an advanced alignment method and apparatus based on satellite trajectory prediction, aiming at solving the above-mentioned drawbacks in the prior art, and aiming at solving the problem of poor accuracy in advanced alignment in the prior art.
The technical scheme adopted by the invention for solving the technical problem is as follows:
a method for advanced alignment based on satellite trajectory prediction comprises the following steps:
acquiring the miss distance of a light spot of a target satellite relative to a tracking visual axis and the tracking visual axis angle of the target satellite;
calculating to obtain real space position information of the target satellite according to the tracking visual axis angle and the miss distance;
performing prediction filtering processing on the target satellite according to the real space position information to obtain a speed prediction value of the target satellite at the next moment;
and calculating to obtain an advanced alignment angle and a prediction direction according to the predicted speed value, and performing advanced alignment processing on the target satellite according to the advanced alignment angle and the prediction direction.
In one implementation, the acquiring the miss distance of the light spot of the target satellite relative to the tracking visual axis and the tracking visual axis angle of the target satellite includes:
acquiring the miss distance of the light spot of the target satellite relative to the tracking visual axis;
acquiring the centroid position of the light spot of the target satellite on the focal plane array by using a tracking detector;
and a photoelectric encoder of a coarse tracking mechanism in the control loop acquires the tracking visual axis azimuth angle and the tracking visual axis pitch angle of the target satellite in real time.
In one implementation, calculating real space position information of the target satellite according to the tracking visual axis angle and the miss distance includes:
obtaining a miss azimuth angle and a miss pitch angle of the target miss distance according to the centroid position;
and calculating to obtain a real azimuth angle of the target satellite according to the tracking visual axis azimuth angle and the off-target azimuth angle, and calculating to obtain a real pitch angle of the target satellite according to the tracking visual axis pitch angle and the off-target pitch angle.
In one implementation, the real azimuth of the target satellite is calculated by:
；
the calculation formula of the real pitch angle of the target satellite is as follows:
；
wherein, the
Is the true azimuth angle, said
To a true pitch angle, said
To track the azimuth of the visual axis, said
In order to track the elevation angle of the boresight,
coordinates of the centroid position of the spot for the target satellite on the focal plane array
The equivalent focal length of the focal plane array.
In one implementation, performing prediction filtering processing on the target satellite according to the real space position information to obtain a predicted value of a velocity of the target satellite at a next time includes:
acquiring a plurality of corresponding real space position information according to the predetermined number of memory points;
and calculating to obtain a predicted speed value of the target satellite at the next moment by utilizing a least square filtering algorithm according to the plurality of real space position information.
In one implementation, the obtaining of multiple corresponding real space position information according to a predetermined number of memory points includes:
the number m of memory points and the order n of the filter are predetermined, and the real azimuth angle and the real pitch angle at m moments nearest to the next moment are obtained.
In one implementation, the calculating, according to a plurality of pieces of the real space position information, a predicted velocity value of the target satellite at a next time by using a least square filtering algorithm includes:
using a least square filtering algorithm to obtain an azimuth prediction coefficient and an azimuth prediction value by taking the minimum mean square error between the m real azimuths and the azimuth prediction value of the target satellite at the next moment as a target;
and obtaining a predicted speed value of the target satellite in the azimuth direction at the next moment according to the azimuth prediction coefficient.
In one implementation, the calculating, according to the plurality of pieces of real space position information, a predicted velocity value of the target satellite at a next time by using a least square filtering algorithm further includes:
obtaining a pitch angle prediction coefficient and a pitch angle prediction value by using a least square filtering algorithm and taking the minimum mean square error between the minimum m real pitch angles and the pitch angle prediction value of the target satellite at the next moment as a target;
and obtaining a predicted speed value of the target satellite in the pitching direction at the next moment according to the pitch angle prediction coefficient.
In one implementation, the position estimate of the target satellite is expressed in relation to time as:
；
wherein, the
Represents a predicted value of a position, said
For predicting coefficients for a location, said
Is time;
and expressing the position prediction value of the target satellite at the next moment as:
；
wherein the content of the first and second substances,
；
the m pieces of real space position information nearest to the next moment are expressed as
；
Solving for
If, if
Nonsingular, then
Obtaining a position prediction coefficient;
the predicted value formula of the speed of the target satellite at the next moment is as follows:
。
in one implementation, the target satellite is predicted to have a velocity in the azimuth direction at the next time when the predicted value is predicted
Representing an azimuth prediction value, said
Representing an azimuth prediction coefficient, said
Representing m real azimuth angles, and substituting the azimuth angle prediction coefficients into the speed prediction value formula after obtaining azimuth angle prediction coefficients to obtain a speed prediction value of the target satellite in the azimuth direction at the next moment;
when predicting a velocity prediction value in a pitch direction of the target satellite at a next time, the target satellite
Representing a predicted value of pitch angle, said
Representing a pitch angle prediction coefficient, said
And representing m real pitch angles, and substituting the pitch angle prediction coefficient into the speed prediction value formula after obtaining a pitch angle prediction coefficient to obtain a speed prediction value of the target satellite in the pitch direction at the next moment.
In one implementation, the advance alignment angle is calculated by the formula:
；
wherein, the
Said
Indicating the azimuth directionVelocity prediction value of
Representing a predicted value of velocity in a pitch direction; the described
Is the speed of light;
the calculation formula of the prediction direction is as follows:
the invention also provides an advanced alignment device based on satellite trajectory prediction, which comprises:
the acquisition module is used for acquiring the miss distance of a light spot of a target satellite relative to a tracking visual axis and the tracking visual axis angle of the target satellite;
the first calculation module is used for calculating real space position information of the target satellite according to the tracking visual axis angle and the miss distance;
the prediction module is used for performing prediction filtering processing on the target satellite according to the real space position information to obtain a speed prediction value of the target satellite at the next moment;
and the second calculation module is used for calculating an advanced alignment angle and a prediction direction according to the predicted speed value and performing advanced alignment processing on the target satellite according to the advanced alignment angle and the prediction direction.
The present invention also provides a satellite terminal, including: a memory, a processor and a satellite trajectory prediction based look-ahead alignment program stored on the memory and executable on the processor, the satellite trajectory prediction based look-ahead alignment program when executed by the processor implementing the steps of the satellite trajectory prediction based look-ahead alignment method as described above.
The invention also provides a computer-readable storage medium storing a computer program executable to implement the steps of the satellite trajectory prediction based look-ahead alignment method as described above.
The invention provides an advanced alignment method and device based on satellite trajectory prediction, wherein the advanced alignment method based on satellite trajectory prediction comprises the following steps: acquiring the miss distance of a light spot of a target satellite relative to a tracking visual axis and the tracking visual axis angle of the target satellite; calculating to obtain real space position information of the target satellite according to the tracking visual axis angle and the miss distance; performing prediction filtering processing on the target satellite according to the real space position information to obtain a speed prediction value of the target satellite at the next moment; and calculating to obtain an advanced alignment angle and a prediction direction according to the predicted speed value, and performing advanced alignment processing on the target satellite according to the advanced alignment angle and the prediction direction. According to the invention, the real space position information is synthesized by tracking the visual axis angle and the miss distance, and prediction filtering processing is carried out according to the real space position information, because the data accuracy and the real-time performance of the tracking visual axis angle and the miss distance are very high, the obtained real space position information is more accurate, the advanced alignment angle and the prediction direction are obtained by the prediction filtering mode, and the accuracy of advanced alignment is improved.
Drawings
Fig. 1 is a schematic diagram of the advanced alignment in communication between two satellite terminals.
Fig. 2 is a functional schematic diagram of an exemplary optical transceiver.
FIG. 3 is a flowchart of a preferred embodiment of the method for satellite trajectory prediction based advanced alignment according to the present invention.
FIG. 4 is a flowchart illustrating the step S100 of the advanced alignment method based on satellite trajectory prediction according to the present invention.
Fig. 5 is a schematic diagram of the advanced alignment function based on prediction filtering in the present invention.
FIG. 6 is a flowchart illustrating the step S200 of the advanced alignment method based on satellite trajectory prediction according to the present invention.
FIG. 7 is a flowchart illustrating the step S300 of the advanced alignment method based on satellite trajectory prediction according to the present invention.
FIG. 8 is a flow chart of the method for obtaining a predicted speed value in the azimuth direction according to the preferred embodiment of the present invention.
FIG. 9 is a flow chart of the method for satellite trajectory prediction based lead alignment according to the present invention for obtaining a predicted speed value in the pitch direction.
Fig. 10 is a diagram showing the effect of the deviation of the azimuth position estimation value from the actual value in the present invention.
Fig. 11 is a diagram showing the effect of the deviation of the estimated azimuth velocity value from the actual value in the present invention.
FIG. 12 is a functional block diagram of a preferred embodiment of the advanced alignment device based on satellite trajectory prediction according to the present invention.
Fig. 13 is a functional block diagram of a satellite terminal according to the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer and clearer, the present invention is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the invention.
Referring to fig. 3, fig. 3 is a flowchart of a method for advanced alignment based on satellite trajectory prediction according to the present invention. As shown in fig. 3, the method for advanced alignment based on satellite trajectory prediction according to the embodiment of the present invention includes the following steps:
step S100, the miss distance of the light spot of the target satellite relative to the tracking visual axis and the tracking visual axis angle of the target satellite are obtained.
Specifically, in the process of establishing and maintaining a communication link of the ATP system of the current satellite-borne optical transceiver, a photoelectric encoder and a capturing and tracking detector of a coarse tracking mechanism in a tracking control loop respectively record high-precision angle and target miss distance information, the precision of the measured data is far higher than that of track forecast external data, the real-time performance is high, and the accuracy of advanced alignment can be improved. Therefore, the satellite terminal acquires the miss distance of the light spot of the target satellite relative to the tracking visual axis and the tracking visual axis angle of the target satellite.
In one implementation, as shown in fig. 4, the step S100 specifically includes:
step S110, acquiring the miss distance of the light spot of the target satellite relative to a tracking visual axis;
step S120, acquiring the centroid position of the light spot of the target satellite on the focal plane array by using a tracking detector;
and S130, a photoelectric encoder of a coarse tracking mechanism in the control loop acquires the tracking visual axis azimuth angle and the tracking visual axis pitch angle of the target satellite in real time.
Specifically, under the condition that the current ATP hardware scheme of the optical transceiver is not changed, the advanced alignment function is realized without depending on orbit prediction, and only the tracking visual axis angle and the miss distance measured by the optical transceiver system on the satellite terminal are utilized. As shown in fig. 5, two main processing links are added to the existing typical optical transceiver architecture, the first is the synthesis of the target location; and secondly, predicting and filtering, namely predicting the position and the speed of a next target through the acquired position information so as to obtain a leading alignment angle. The tracking visual axis angle comprises a tracking visual axis azimuth angle and a tracking visual axis pitch angle.
The step S100 is followed by: and S200, calculating to obtain real space position information of the target satellite according to the tracking visual axis angle and the miss distance.
Specifically, the satellite terminal synthesizes the tracking visual axis angle and the miss distance into the real pointing direction of the target optical axis.
In an implementation manner, as shown in fig. 6, the step S200 specifically includes:
s210, obtaining a miss azimuth angle and a miss pitch angle of the target miss distance according to the centroid position;
step S220, calculating to obtain a real azimuth angle of the target satellite according to the tracking visual axis azimuth angle and the off-target azimuth angle, and calculating to obtain a real pitch angle of the target satellite according to the tracking visual axis pitch angle and the off-target pitch angle.
That is to say, when synthesizing the target position, the optical transceiver capturing and tracking detector adopts a focal plane array, and the equivalent focal length is f. The photoelectric encoder in the control loop acquires the azimuth and the pitch angle in real time, the azimuth and the pitch angle are A0 and E0 respectively, and the position of the light spot centroid on the focal plane array
。
The angle converted into the miss distance is respectively
、
From the projection relationship, we can obtain:
in engineering, accuracy requirements are considered, angle calculation of the miss distance is simplified, and the first terms of the two formulas are reserved. Therefore, the true azimuth angle a and the true pitch angle E of the true spatial position synthesized by the miss distance and the photoelectric code disc are respectively:
；
(ii) a Wherein, the
Is the true azimuth angle, said
To a true pitch angle, said
To track the azimuth of the visual axis, said
In order to track the elevation angle of the boresight,
coordinates of the centroid position of the spot for the target satellite on the focal plane array
Is the equivalent focal length of the focal plane array.
The step S200 is followed by: and S300, performing prediction filtering processing on the target satellite according to the real space position information to obtain a speed predicted value of the target satellite at the next moment.
The invention adopts a prediction filtering method to predict the position and the speed of the target satellite at the next moment, thereby obtaining the advanced alignment angle. The predictive filtering principle is to derive target information for the next step or steps from the known position of the target signal.
In one implementation, as shown in fig. 7, the step S300 specifically includes:
step S310, acquiring a plurality of corresponding real space position information according to a predetermined memory point number;
and step S320, calculating to obtain a predicted speed value of the target satellite at the next moment by using a least square filtering algorithm according to the real space position information.
Commonly used prediction filtering methods include finite memory least squares, kalman filtering, and the like. The Kalman prediction filtering method is high in precision, large in calculation amount, dependent on target motion characteristics and accurate observer parameters and difficult to meet the requirement of a satellite environment. Moreover, the prediction requires a certain time for position extraction based on the target motion information provided by the detector, and the lag affects the accuracy of the advance alignment, so that the prediction lag is required to be small. The least square method prediction algorithm is simple, small in delay and high in accuracy, and therefore the least square filtering algorithm is selected by the method aiming at prediction filtering of the advanced alignment angle.
In an embodiment, the step S310 specifically includes: the number m of memory points and the order n of the filter are predetermined, and the real azimuth angle and the real pitch angle at m moments nearest to the next moment are obtained.
In particular, the key to the least square polynomial filtering algorithm is to select an appropriate number m of memory points and an appropriate filter order n. The selection can be made according to the satellite motion characteristics, and in general, m and n of the filter can not be too large or too small. If the target mobility is strong and the system error needs to be reduced, m is increased and n is reduced; on the contrary, when the target mobility is weak and the random error needs to be reduced, the value of m should be reduced and the value of n should be increased appropriately.
The predicted speed value is obtained by synthesizing the speeds in the azimuth angle direction and the pitch angle direction, so the method needs to respectively calculate the predicted speed value of the target satellite in the azimuth direction at the next moment and the predicted speed value of the target satellite in the pitch direction at the next moment.
Specifically, as shown in fig. 8, the step S320 specifically includes:
step S321a, by using a least square filtering algorithm, obtaining an azimuth prediction coefficient and an azimuth prediction value by taking the minimum mean square error between the minimum m real azimuths and the azimuth prediction value of the target satellite at the next moment as a target;
and step S322a, obtaining a predicted speed value of the target satellite in the azimuth direction at the next moment according to the azimuth prediction coefficient.
As shown in fig. 9, the step S320 further includes:
s321b, obtaining a pitch angle prediction coefficient and a pitch angle prediction value by using a least square filtering algorithm and taking the minimum mean square error between the minimum m real pitch angles and the pitch angle prediction value of the target satellite at the next moment as a target;
and step S322b, obtaining a speed predicted value of the target satellite in the pitching direction at the next moment according to the pitch angle prediction coefficient.
Specifically, the relationship between the position estimate of the target satellite and time t is approximated by an nth-order polynomial p (t), i.e., the relationship between the position estimate of the target satellite and time is expressed as:
(ii) a Wherein, the
Represents a predicted value of a position, said
For predicting coefficients for a location, said
Is time.
Representing the satellite trajectory coordinates of the target satellite as p j (t) (j =1,2, \8230m), representing the predicted value of the position of the target satellite at the next time instant as:
(ii) a Wherein the content of the first and second substances,
，
(ii) a The m pieces of real space position information nearest to the next moment are expressed as
。
To solve for the best estimate of B, the least squares method is used to minimize the minimum mean square error between the true spatial location information and the location prediction, i.e., the
(ii) a If it is
Non-singularity, B has a unique solution,
and obtaining the position prediction coefficient.
The predicted position value of the target satellite at the next moment can be derived by a polynomial with B as a coefficient:
(ii) a The predicted value formula of the speed of the target satellite at the next moment is as follows:
。
when predicting a predicted value of the velocity in the azimuth direction at the next time of the target satellite, the method includes
Representing an azimuth prediction value, said
Representing an azimuth prediction coefficient, said
And representing m real azimuth angles, and substituting the azimuth angle prediction coefficient into the speed prediction value formula after obtaining an azimuth angle prediction coefficient to obtain a speed prediction value of the target satellite in the azimuth direction at the next moment.
When predicting a velocity prediction value in a pitch direction of the target satellite at a next time, the target satellite
Representing a predicted value of pitch angle, said
Representing a pitch angle prediction coefficient, said
And representing m real pitch angles, and substituting the pitch angle prediction coefficient into the speed prediction value formula after obtaining a pitch angle prediction coefficient to obtain a speed prediction value of the target satellite in the pitch direction at the next moment.
The step S300 is followed by: and S400, calculating to obtain an advanced alignment angle and a prediction direction according to the predicted speed value, and performing advanced alignment processing on the target satellite according to the advanced alignment angle and the prediction direction. And after the advanced alignment angle and the predicted direction are calculated according to the predicted speed value, the satellite terminal drives the actuating mechanism to realize the advanced alignment function.
In one embodiment, the advanced alignment angle is calculated by the formula:
；
wherein, the
The above-mentioned
Representing a predicted value of velocity in an azimuth direction, said
Representing a predicted value of velocity in a pitch direction; the above-mentioned
Is the speed of light;
the calculation formula of the prediction direction is as follows:
taking advance angle prediction in satellite azimuth direction as an example, assuming that the relative motion position in the azimuth direction between satellites changes to x =4+3sin (2 t), the velocity v =6cos (2 t), the number of memory points is selected to be 7, the filter order is selected to be 4, and the position is selected to be 4The prediction polynomial is
(ii) a The velocity prediction polynomial is
. According to the obtained actual track coordinates x (t) of the satellite of the first 7 frames k ) (k =1,2, \82307; 7), calculating an estimated value of B by a least square method to minimize the variance with the measured value, and calculating the position and the speed of the 8 th frame; and then, obtaining a new target position at each moment along with time intervals, deleting the oldest real space position information, updating the estimated value of the B by a least square method, and continuously calculating the position and the speed of the next moment (namely the next frame) and the like. The simulation results of the actual values and the estimated values of the azimuth and the azimuth velocity are shown in fig. 10 and 11, respectively. From the simulation results, the mean square error of the azimuth position is 1.6e-05, and the mean square error of the azimuth velocity is 0.0064.
The invention does not depend on the complex transformation of orbit data and each reference coordinate system, only depends on the photoelectric encoder and the tracking detector of the optical transmitter and receiver, estimates the current real target position, realizes the advanced alignment function and improves the accuracy of advanced alignment; the prediction algorithm adopts a classical least square algorithm, is simple and reliable, has small processing delay, further improves the accuracy of the advanced alignment, and does not need to modify the hardware architecture of the existing optical transceiver.
Further, as shown in fig. 12, based on the above advanced alignment method based on satellite trajectory prediction, the present invention also provides an advanced alignment apparatus based on satellite trajectory prediction, including:
the acquisition module 100 is configured to acquire an off-target amount of a light spot of a target satellite relative to a tracking visual axis and a tracking visual axis angle of the target satellite;
the first calculation module 200 is configured to calculate real space position information of the target satellite according to the tracking visual axis angle and the miss distance;
the prediction module 300 is configured to perform prediction filtering processing on the target satellite according to the real space position information to obtain a predicted speed value of the target satellite at a next moment;
and a second calculating module 400, configured to calculate a leading alignment angle and a predicted direction according to the predicted speed value, and perform leading alignment processing on the target satellite according to the leading alignment angle and the predicted direction.
As shown in fig. 13, the present invention also provides a satellite terminal, including: a memory 20, a processor 10 and a satellite trajectory prediction based look-ahead alignment program 30 stored on the memory 20 and executable on the processor 10, the satellite trajectory prediction based look-ahead alignment program 30 when executed by the processor 10 implementing the steps of the satellite trajectory prediction based look-ahead alignment method as described above.
The invention also provides a computer-readable storage medium storing a computer program executable to implement the steps of the satellite trajectory prediction based look-ahead alignment method as described above.
In summary, the advanced alignment method and apparatus based on satellite trajectory prediction disclosed in the present invention includes: acquiring the miss distance of a light spot of a target satellite relative to a tracking visual axis and the tracking visual axis angle of the target satellite; calculating to obtain real space position information of the target satellite according to the tracking visual axis angle and the miss distance; performing prediction filtering processing on the target satellite according to the real space position information to obtain a speed prediction value of the target satellite at the next moment; and calculating to obtain an advanced alignment angle and a prediction direction according to the predicted speed value, and performing advanced alignment processing on the target satellite according to the advanced alignment angle and the prediction direction. According to the invention, the real space position information is synthesized by tracking the visual axis angle and the miss distance, and prediction filtering processing is carried out according to the real space position information, because the data accuracy and the real-time performance of the tracking visual axis angle and the miss distance are very high, the obtained real space position information is more accurate, the advanced alignment angle and the prediction direction are obtained by the prediction filtering mode, and the accuracy of advanced alignment is improved.
It is to be understood that the invention is not limited to the examples described above, but that modifications and variations may be effected thereto by those of ordinary skill in the art in light of the foregoing description, and that all such modifications and variations are intended to be within the scope of the invention as defined by the appended claims.
Claims (4)
1. A method for advanced alignment based on satellite trajectory prediction is characterized by comprising the following steps:
acquiring the miss distance of a light spot of a target satellite relative to a tracking visual axis and the tracking visual axis angle of the target satellite;
calculating to obtain real space position information of the target satellite according to the tracking visual axis angle and the miss distance;
performing prediction filtering processing on the target satellite according to the real space position information to obtain a speed prediction value of the target satellite at the next moment;
calculating to obtain an advanced alignment angle and a prediction direction according to the predicted speed value, and performing advanced alignment processing on the target satellite according to the advanced alignment angle and the prediction direction;
the acquiring of the miss distance of the light spot of the target satellite relative to the tracking visual axis and the tracking visual axis angle of the target satellite includes:
acquiring the miss distance of the light spot of the target satellite relative to the tracking visual axis;
acquiring the centroid position of the light spot of the target satellite on the focal plane array by using a tracking detector;
a photoelectric encoder of a coarse tracking mechanism in a control loop acquires a tracking visual axis azimuth angle and a tracking visual axis pitch angle of the target satellite in real time;
calculating to obtain real space position information of the target satellite according to the tracking visual axis angle and the miss distance, wherein the method comprises the following steps:
obtaining the miss azimuth angle and the miss pitch angle of the miss amount according to the centroid position;
calculating to obtain a real azimuth angle of the target satellite according to the tracking visual axis azimuth angle and the off-target azimuth angle, and calculating to obtain a real pitch angle of the target satellite according to the tracking visual axis pitch angle and the off-target pitch angle;
the calculation formula of the true azimuth angle of the target satellite is as follows:
；
the calculation formula of the real pitch angle of the target satellite is as follows:
；
wherein, the
Is the true azimuth angle, said
To a true pitch angle, said
To track the azimuth of the visual axis, said
In order to track the elevation angle of the boresight,
coordinates of the centroid position of the spot for the target satellite on the focal plane array
Is the equivalent focal length of the focal plane array;
performing prediction filtering processing on the target satellite according to the real space position information to obtain a predicted value of the speed of the target satellite at the next moment, wherein the prediction filtering processing comprises the following steps:
acquiring a plurality of corresponding real space position information according to the predetermined number of memory points;
calculating to obtain a predicted value of the speed of the target satellite at the next moment by using a least square filtering algorithm according to the real space position information;
the acquiring of the corresponding real space position information according to the predetermined number of the memory points comprises:
predetermining the number m of memory points and the order n of a filter, and acquiring real azimuth angles and real pitch angles of m moments nearest to the next moment;
the calculating the predicted value of the velocity of the target satellite at the next moment by using a least square filtering algorithm according to the plurality of pieces of real space position information comprises the following steps:
using a least square filtering algorithm to obtain an azimuth prediction coefficient and an azimuth prediction value by taking the minimum mean square error between the m real azimuths and the azimuth prediction value of the target satellite at the next moment as a target;
obtaining a predicted speed value of the target satellite in the azimuth direction at the next moment according to the azimuth prediction coefficient;
the method for calculating and obtaining the predicted value of the velocity of the target satellite at the next moment by using the least square filtering algorithm according to the plurality of real space position information further comprises the following steps:
obtaining a pitch angle prediction coefficient and a pitch angle prediction value by using a least square filtering algorithm and taking the minimum mean square error between the minimum m real pitch angles and the pitch angle prediction value of the target satellite at the next moment as a target;
obtaining a speed predicted value of the target satellite in the pitching direction at the next moment according to the pitch angle prediction coefficient;
the relationship between the position predicted value of the target satellite and the time is expressed as follows:
；
wherein, the
Representing a position prediction value, said
For predicting coefficients for a location, said
Is time;
and expressing the position prediction value of the target satellite at the next moment as:
；
wherein the content of the first and second substances,
；
the m pieces of real space position information nearest to the next moment are expressed as
；
Solving for
If at all
Not singularity, then
Obtaining a position prediction coefficient;
the predicted value formula of the speed of the target satellite at the next moment is as follows:
；
when predicting a predicted value of the velocity in the azimuth direction at the next time of the target satellite, the method includes
Representing an azimuth prediction value, said
Representing an azimuth prediction coefficient, said
Representing m real azimuth angles, and substituting the azimuth angle prediction coefficients into the speed prediction value formula after obtaining azimuth angle prediction coefficients to obtain a speed prediction value of the target satellite in the azimuth direction at the next moment;
when predicting a velocity prediction value in a pitch direction of the target satellite at a next time, the target satellite
Representing a predicted value of pitch angle, said
Representing a pitch angle prediction coefficient, said
Representing m real pitch angles, and substituting the pitch angle prediction coefficients into the speed prediction value formula after obtaining pitch angle prediction coefficients to obtain a speed prediction value of the target satellite in the pitch direction at the next moment;
the calculation formula of the advanced alignment angle is as follows:
；
wherein, the
Said
Representing a predicted value of velocity in an azimuth direction, said
Representing a predicted value of velocity in a pitch direction; the above-mentioned
Is the speed of light;
the calculation formula of the prediction direction is as follows:
2. an advance alignment device based on satellite trajectory prediction, comprising:
the acquisition module is used for acquiring the miss distance of a light spot of a target satellite relative to a tracking visual axis and the tracking visual axis angle of the target satellite;
the first calculation module is used for calculating to obtain real space position information of the target satellite according to the tracking visual axis angle and the miss distance;
the prediction module is used for performing prediction filtering processing on the target satellite according to the real space position information to obtain a speed prediction value of the target satellite at the next moment;
the second calculation module is used for calculating to obtain an advanced alignment angle and a prediction direction according to the predicted speed value and carrying out advanced alignment processing on the target satellite according to the advanced alignment angle and the prediction direction;
the acquiring of the miss distance of the light spot of the target satellite relative to the tracking visual axis and the tracking visual axis angle of the target satellite includes:
acquiring the miss distance of the light spot of the target satellite relative to the tracking visual axis;
acquiring the centroid position of the light spot of the target satellite on the focal plane array by using a tracking detector;
a photoelectric encoder of a coarse tracking mechanism in a control loop acquires a tracking visual axis azimuth angle and a tracking visual axis pitch angle of the target satellite in real time;
calculating to obtain real space position information of the target satellite according to the tracking visual axis angle and the miss distance, wherein the method comprises the following steps:
obtaining the miss azimuth angle and the miss pitch angle of the miss amount according to the centroid position;
calculating to obtain a real azimuth angle of the target satellite according to the tracking visual axis azimuth angle and the off-target azimuth angle, and calculating to obtain a real pitch angle of the target satellite according to the tracking visual axis pitch angle and the off-target pitch angle;
the calculation formula of the true azimuth angle of the target satellite is as follows:
；
the calculation formula of the real pitch angle of the target satellite is as follows:
；
wherein, the
As a true azimuth angle, said
To a true pitch angle, said
To track the azimuth of the visual axis, said
In order to track the elevation angle of the boresight,
coordinates of the centroid position of the spot for the target satellite on the focal plane array
Is the equivalent focal length of the focal plane array;
performing prediction filtering processing on the target satellite according to the real space position information to obtain a predicted value of the speed of the target satellite at the next moment, wherein the prediction filtering processing comprises the following steps:
acquiring a plurality of corresponding real space position information according to the predetermined number of memory points;
calculating to obtain a predicted value of the speed of the target satellite at the next moment by using a least square filtering algorithm according to the real space position information;
the acquiring of the corresponding real space position information according to the predetermined number of the memory points comprises:
predetermining the number m of memory points and the order n of a filter, and acquiring real azimuth angles and real pitch angles of m moments nearest to the next moment;
the calculating by using a least square filtering algorithm according to the plurality of real space position information to obtain the predicted value of the velocity of the target satellite at the next moment includes:
using a least square filtering algorithm to obtain an azimuth angle prediction coefficient and an azimuth angle prediction value by taking the minimum mean square error between the minimum m real azimuth angles and the azimuth angle prediction value of the target satellite at the next moment as a target;
obtaining a predicted speed value of the target satellite in the azimuth direction at the next moment according to the azimuth prediction coefficient;
the calculating by using a least square filtering algorithm according to the plurality of real space position information to obtain the predicted value of the velocity of the target satellite at the next moment further comprises:
obtaining a pitch angle prediction coefficient and a pitch angle prediction value by using a least square filtering algorithm and taking the minimum mean square error between the minimum m real pitch angles and the pitch angle prediction value of the target satellite at the next moment as a target;
obtaining a speed predicted value of the target satellite in the pitching direction at the next moment according to the pitch angle prediction coefficient;
the relationship between the position predicted value of the target satellite and the time is expressed as follows:
；
wherein, the
Represents a predicted value of a position, said
For predicting coefficients for a location, said
Is time;
and expressing the position prediction value of the target satellite at the next moment as:
；
wherein the content of the first and second substances,
；
the m pieces of real space position information nearest to the next moment are expressed as
；
Solving for
If, if
Nonsingular, then
Obtaining a position prediction coefficient;
the predicted speed value formula of the target satellite at the next moment is as follows:
；
when predicting a predicted value of the velocity in the azimuth direction at the next time of the target satellite, the target satellite is predicted based on the predicted value
Representing an azimuth prediction value, said
Representing an azimuth prediction coefficient, said
Representing m real azimuth angles, and substituting the azimuth angle prediction coefficients into the speed prediction value formula after obtaining azimuth angle prediction coefficients to obtain a speed prediction value of the target satellite in the azimuth direction at the next moment;
when predicting a predicted value of a velocity in a pitch direction at a next time of the target satellite, the target satellite is predicted based on the predicted value
Representing a predicted value of pitch angle, said
Representing a pitch angle prediction coefficient, said
Representing m real pitch angles, and substituting the pitch angle prediction coefficients into the speed prediction value formula after obtaining pitch angle prediction coefficients to obtain a speed prediction value of the target satellite in the pitch direction at the next moment;
the calculation formula of the advanced alignment angle is as follows:
；
wherein, the
Said
Representing a predicted value of velocity in an azimuth direction, said
Representing a predicted value of velocity in a pitch direction; the above-mentioned
Is the speed of light;
the calculation formula of the prediction direction is as follows:
3. a satellite terminal, comprising: memory, processor and a satellite trajectory prediction based look-ahead alignment program stored on the memory and executable on the processor, the satellite trajectory prediction based look-ahead alignment program when executed by the processor implementing the steps of the satellite trajectory prediction based look-ahead alignment method as claimed in claim 1.
4. A computer-readable storage medium, characterized in that it stores a computer program executable for implementing the steps of the satellite trajectory prediction based look-ahead alignment method according to claim 1.
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