A coaxiality on-orbit calibration method and device of a spaceborne laser communication terminal

Abstract

The present specification relates to the technical field of satellite laser communication, and provides a coaxiality on-orbit calibration method and device for a satellite-borne laser communication terminal, the method comprising: obtaining a first pointing vector of a telescope optical axis of a satellite-borne laser communication terminal based on an external reference coordinate system; obtaining a second pointing vector of a star camera optical axis of the satellite-borne laser communication terminal based on a local reference coordinate system; transforming the first pointing vector into a third pointing vector in the local reference coordinate system; determining a coaxiality deviation of the third pointing vector relative to the second pointing vector; and performing coaxiality compensation according to the coaxiality deviation. The embodiments of the present specification can realize accurate calibration of the coaxiality of a satellite-borne laser communication terminal on orbit.

Description

TECHNICAL FIELD

[0001] The present specification relates to the technical field of satellite laser communication, and in particular to a coaxiality on-orbit calibration method and device of a satellite-borne laser communication terminal. BACKGROUND

[0002] During the in-orbit process of a satellite-borne laser communication terminal, the terminal may be disturbed or affected by launch impact, weightlessness, thermal deformation, etc., thereby easily causing a large deviation in the coaxiality of a star camera and a telescope of the satellite-borne laser communication terminal. Therefore, it is necessary to accurately calibrate the coaxiality of the star camera and the telescope of the satellite-borne laser communication terminal on orbit. SUMMARY

[0003] The purpose of the embodiments of the present specification is to provide a coaxiality on-orbit calibration method and device of a satellite-borne laser communication terminal, so as to accurately calibrate the coaxiality of a satellite-borne laser communication terminal on orbit.

[0004] To achieve the above purpose, on one hand, the embodiments of the present specification provide a coaxiality on-orbit calibration method of a satellite-borne laser communication terminal, comprising:

[0005] obtaining a first pointing vector of a telescope optical axis of a satellite-borne laser communication terminal based on an external reference coordinate system;

[0006] obtaining a second pointing vector of a star camera optical axis of the satellite-borne laser communication terminal based on a local reference coordinate system;

[0007] transforming the first pointing vector into a third pointing vector in the local reference coordinate system;

[0008] determining a coaxiality deviation of the third pointing vector relative to the second pointing vector;

[0009] performing coaxiality compensation according to the coaxiality deviation.

[0010] In the coaxiality on-orbit calibration method of the embodiments of the present specification, the obtaining of the first pointing vector of the telescope optical axis of the satellite-borne laser communication terminal based on the external reference coordinate system comprises:

[0011] obtaining a first position vector of a home star at a specific moment based on an external reference coordinate system; the home star is a satellite in which the satellite-borne laser communication terminal is located;

[0012] based on an interstellar laser link between the home star and a target star, obtaining a second position vector of the target star at the specific moment based on the external reference coordinate system;

[0013] determining a position vector difference between the second position vector and the first position vector;

[0014] The position vector difference is determined as a first pointing vector of the external reference coordinate system based on the optical axis of the telescope at the specific moment.

[0015] The coaxiality on-orbit calibration method of the embodiment of the present specification further comprises, after determining the position vector difference between the second position vector and the first position vector:

[0016] The position vector difference is converted into a unit vector.

[0017] The unit vector is determined as a first pointing vector of the external reference coordinate system based on the optical axis of the telescope at the specific moment.

[0018] The coaxiality on-orbit calibration method of the embodiment of the present specification, the second pointing vector of the star camera optical axis of the spaceborne laser communication terminal based on the local reference coordinate system comprises:

[0019] Based on the star image captured by the star camera at a specific moment, the second pointing vector of the star camera based on the star camera coordinate system at the specific moment is determined.

[0020] In the coaxiality on-orbit calibration method of the embodiment of the present specification, the second pointing vector is characterized based on a quaternion.

[0021] In the coaxiality on-orbit calibration method of the embodiment of the present specification, the first pointing vector is transformed into a third pointing vector in the local reference coordinate system, comprising:

[0022] According to the quaternion, a rotation matrix of the external reference coordinate system transformed to the star camera coordinate system at the specific moment is determined;

[0023] The first pointing vector is right multiplied by the rotation matrix to obtain a third pointing vector of the first pointing vector in the star camera coordinate system.

[0024] In the coaxiality on-orbit calibration method of the embodiment of the present specification, the coaxiality deviation of the third pointing vector relative to the second pointing vector is determined, comprising:

[0025] The azimuth coaxiality deviation of the third pointing vector relative to the second pointing vector is determined; and,

[0026] The pitch coaxiality deviation of the third pointing vector relative to the second pointing vector is determined.

[0027] In the coaxiality on-orbit calibration method of the embodiment of the present specification, the coaxiality compensation is performed according to the coaxiality deviation, comprising:

[0028] According to the azimuth coaxiality deviation and the elevation coaxiality deviation, a terminal pointing algorithm of the spaceborne laser communication terminal is corrected.

[0029] In the coaxiality on-orbit calibration method of the embodiments of the present specification, after the coaxiality deviation of the third pointing vector relative to the second pointing vector is determined, the method further comprises:

[0030] The coaxiality deviations of the telescope optical axis and the star camera optical axis at multiple different times are obtained;

[0031] A concentration quantity value of the coaxiality deviations at the multiple different times is determined;

[0032] Correspondingly, the coaxiality compensation according to the coaxiality deviation comprises:

[0033] The terminal pointing algorithm of the spaceborne laser communication terminal is corrected according to the concentration quantity value.

[0034] In the coaxiality on-orbit calibration method of the embodiments of the present specification, before the concentration quantity value of the coaxiality deviations at the multiple different times is determined, the method further comprises:

[0035] Outliers in the coaxiality deviations at the multiple different times are removed.

[0036] In the coaxiality on-orbit calibration method of the embodiments of the present specification, the external reference coordinate system comprises a J2000 inertial coordinate system.

[0037] On the other hand, the embodiments of the present specification also provide a coaxiality on-orbit calibration device of a spaceborne laser communication terminal, comprising:

[0038] A first acquisition module is configured to acquire a first pointing vector of a telescope optical axis of a spaceborne laser communication terminal based on an external reference coordinate system;

[0039] A second acquisition module is configured to acquire a second pointing vector of a star camera optical axis of the spaceborne laser communication terminal based on a local reference coordinate system;

[0040] A vector transformation module is configured to transform the first pointing vector into a third pointing vector in the local reference coordinate system;

[0041] A deviation determination module is configured to determine a coaxiality deviation of the third pointing vector relative to the second pointing vector;

[0042] A deviation compensation module is configured to perform coaxiality compensation according to the coaxiality deviation.

[0043] On the other hand, the embodiments of the present application also provide a spaceborne laser communication terminal, comprising:

[0044] at least one processor; and

[0045] at least one memory storing instructions thereon that, when executed by the at least one processor alone or in combination, cause the spaceborne laser communication terminal to perform the method described above.

[0046] In another aspect, the embodiments of the present application further provide a computer storage medium storing instructions, wherein the instructions, when executed by at least one processor of a computer device alone or in combination, cause the computer device to perform the method described above.

[0047] In another aspect, the embodiments of the present application further provide a computer program product comprising instructions, wherein the instructions, when executed by at least one processor of a computer device alone or in combination, cause the computer device to perform the method described above.

[0048] In another aspect, the embodiments of the present application further provide a chip, wherein the chip comprises circuitry configured to perform the method described above.

[0049] It can be seen from the technical solutions provided by the above embodiments of the present specification that, in the embodiments of the present specification, by transforming the first pointing vector of the telescope optical axis into a third pointing vector in a local reference coordinate system, the coaxiality deviation of the telescope optical axis and the star camera optical axis can be compared and determined in the same reference coordinate system, and coaxiality compensation can be performed accordingly. Since the first pointing vector of the telescope optical axis is obtained based on an external reference coordinate system, by introducing the external reference coordinate system as an external reference, which is independent of the internal structure of the terminal, the coaxiality deviation can be avoided from being affected by the deformation of the terminal, thereby realizing accurate calibration of the coaxiality of the spaceborne laser communication terminal in orbit. BRIEF DESCRIPTION OF DRAWINGS

[0050] In order to more clearly illustrate the technical solutions of the embodiments of the present specification or the prior art, the drawings needed in the embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments described in the present specification, and those skilled in the art can also obtain other drawings according to these drawings without creative labor. In the drawings:

[0051] Figure 1 A schematic diagram of satellite laser communication in some embodiments of the present specification is shown;

[0052] Figure 2 A schematic diagram of the telescope optical axis and the star camera optical axis of the spaceborne laser communication terminal in some embodiments of the present specification is shown;

[0053] Figure 3A flow chart of the on-orbit calibration method of the coaxiality of the spaceborne laser communication terminal in some embodiments of the present specification is shown.

[0054] Figure 4 A schematic diagram of the coaxiality deviation of the telescope optical axis and the star camera optical axis in an exemplary embodiment of the present specification is shown. Figure 3 A flow chart of another method of acquiring the first pointing vector of the telescope optical axis based on the external reference coordinate system in the method shown is shown.

[0055] Figure 5 A schematic diagram of the coaxiality deviation of the telescope optical axis and the star camera optical axis in an exemplary embodiment of the present specification is shown. Figure 3 A flow chart of another method of acquiring the first pointing vector of the telescope optical axis based on the external reference coordinate system in the method shown is shown.

[0056] Figure 6 A schematic diagram of the coaxiality deviation of the telescope optical axis and the star camera optical axis in an exemplary embodiment of the present specification is shown. Figure 3 A flow chart of the method of transforming the first pointing vector into the third pointing vector in the local reference coordinate system in the method shown is shown.

[0057] Figure 7 A schematic diagram of the coaxiality deviation of the telescope optical axis and the star camera optical axis in an exemplary embodiment of the present specification is shown.

[0058] Figure 8 A flow chart of the on-orbit calibration method of the coaxiality of the spaceborne laser communication terminal in some embodiments of the present specification is shown.

[0059] Figure 9 A structural block diagram of the on-orbit calibration device of the coaxiality of the spaceborne laser communication terminal in some embodiments of the present specification is shown.

[0060] Figure 10 A structural block diagram of the spaceborne laser communication terminal in some embodiments of the present application is shown.

[0061]

Explanation of Reference Signs

[0062] 10: telescope;

[0063] 20: star camera;

[0064] 91: first acquisition module;

[0065] 92: second acquisition module;

[0066] 93: vector transformation module;

[0067] 94: deviation determination module;

[0068] 95: deviation compensation module;

[0069] 1000: spaceborne laser communication terminal;

[0070] 1010: processor;

[0071] 1020: memory;

[0072] 1030: program;

[0073] 1040: transceiver;

[0074] 1050: antenna. DETAILED DESCRIPTION

[0075] In order for those skilled in the art to better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be clearly and completely described in the following with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should be within the scope of protection of the present application.

[0076] It should be noted that in the embodiments of the present application, the user information (including but not limited to user equipment information, user personal information, etc.) and data (including but not limited to data for analysis, stored data, displayed data, etc.) involved are all information and data authorized by the user and fully authorized by all parties, that is, the acquisition, transmission, storage, use, processing, etc. of data in the technical solutions of the present application all comply with the relevant provisions of national laws and regulations.

[0077] In the description of the present application, unless otherwise specified, "and / or" is a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B can mean that there are three cases of A alone, A and B together, and B alone, where A and B can be singular or plural. And in the description of the present application, unless otherwise specified, "multiple" means two or more than two. "At least one (one)" or similar expressions mean any combination of these items, including any combination of single (one) or multiple items. For example, at least one of a, b, or c can mean a, b, c, ab, a-c, b-c, or a-b-c, where a, b, and c can be single or multiple.

[0078] In the present application, in order to determine whether a certain condition is met, the expressions greater than or less than can be used, but this is only for the description of an example, and is not intended to exclude the above or below. The condition described as "above" can be replaced by "greater than", the condition described as "below" can be replaced by "less than", and the condition described as "above and less than" can be replaced by "greater than and below". And below, "A" to "B" means at least one of the elements from A (including A) to B (including B).

[0079] In the embodiments of the present application, the singular form "a", "an", "the" and the like include the plural form, should be broadly understood as "one" or "a kind of" and not limited to the meaning of "one"; in addition, the term "said" should be understood to include both the singular form and the plural form, unless the context clearly indicates otherwise. In addition, the term "according to" should be understood as "at least partially according to", and the term "based on" should be understood as "at least partially based on", unless the context clearly indicates otherwise.

[0080] The present application provides method operation steps as described in the embodiments or flowcharts, but more or fewer operation steps can be included based on conventional or non-creative labor. The order of steps listed in the embodiments is only one of the many step execution orders, and does not represent the only execution order. In actual system or device product execution, the method order shown in the embodiments or the drawings can be executed in sequence or in parallel.

[0081] Compared with traditional satellite communication, satellite laser communication is to modulate the information to be transmitted (such as voice, data, image) to a laser beam, transmit through a free space optical channel (space or atmosphere), and receive and demodulate at the receiving end to recover the original information. As shown in Figure 1 Satellite laser communication can include inter-satellite laser communication and satellite-ground laser communication. Among them, inter-satellite laser communication refers to laser communication between satellites; satellite-ground laser communication refers to laser communication between satellites and the ground (such as fixed ground stations, mobile ground stations, airborne terminals, handheld / portable terminals); among them, mobile ground stations refer to ground stations carried on movable platforms such as vehicles and ships; airborne terminals refer to laser communication terminals installed on aircraft or high-altitude long-endurance unmanned aerial vehicles, etc.

[0082] In satellite laser communication, the laser communication terminal carried on the satellite is called a satellite-borne laser communication terminal. The satellite-borne laser communication terminal contains a star camera and a telescope. Among them, the core role of the telescope is to output a laser beam (uplink) and receive a laser signal from the other party (such as a satellite, etc.) (downlink). The core role of the star camera (or star sensor) is to accurately determine the real-time attitude (including pointing) of the entire satellite-borne laser communication terminal in the universe space by observing background stars (the positions of these stars in inertial space are known and extremely stable). Therefore, the star camera and the telescope are both key components of the same satellite-borne laser communication terminal, and they are integrated together to work cooperatively to complete the high-precision satellite laser communication task.

[0083] Because the laser beam divergence angle is very small (usually in tens of micro-radians), it requires that the spaceborne laser communication terminal has extremely precise alignment to the target; therefore, before establishing a satellite laser communication connection, the pointing of the spaceborne laser communication terminal needs to be precisely calibrated. Precise calibration of the coaxiality of the star camera and the telescope of the spaceborne laser communication terminal is a technical prerequisite for the pointing calibration of the spaceborne laser communication terminal.

[0084] Generally, during the ground installation and adjustment stage of the spaceborne laser communication terminal, the coaxiality of the telescope optical axis and the star camera optical axis of the spaceborne laser communication terminal has been calibrated. However, during the orbiting process of the spaceborne laser communication terminal, due to interference or influence such as launch impact, weightlessness, thermal deformation, etc., the coaxiality of the star camera and the telescope of the spaceborne laser communication terminal is likely to deviate relatively greatly. Therefore, it is necessary to calibrate the coaxiality of the star camera and the telescope of the spaceborne laser communication terminal in orbit.

[0085] Figure 2 FIG. 1 shows a schematic diagram of the relative positional relationship between the optical axis of the telescope 10 (i.e., the telescope optical axis) and the optical axis of the star camera 20 (i.e., the star camera optical axis) of the spaceborne laser communication terminal in the embodiments of the present specification; after the spaceborne laser communication terminal orbits, the coaxiality of the star camera 20 and the telescope 10 of the spaceborne laser communication terminal in orbit can be precisely calibrated, thereby providing a reliable basis for subsequent pointing calibration of the spaceborne laser communication terminal.

[0086] The embodiments of the present specification provide a coaxiality in-orbit calibration method of a spaceborne laser communication terminal, which can be applied to the spaceborne laser communication terminal side described above, and with reference to FIG. 1, in some embodiments of the present specification, the coaxiality in-orbit calibration method of the spaceborne laser communication terminal can include the following steps: Figure 3

[0087] Step 301: Obtain a first pointing vector of a telescope optical axis of a spaceborne laser communication terminal based on an external reference coordinate system.

[0088] Step 302: Obtain a second pointing vector of a star camera optical axis of the spaceborne laser communication terminal based on a local reference coordinate system.

[0089] Step 303: Transform the first pointing vector into a third pointing vector in the local reference coordinate system.

[0090] Step 304: Determine the coaxiality deviation of the third pointing vector relative to the second pointing vector.

[0091] Step 305: Perform coaxiality compensation according to the coaxiality deviation.

[0092] ​In the embodiments of the present specification, by transforming the first pointing vector of the telescope optical axis into a third pointing vector in a local reference coordinate system, the coaxiality deviation of the telescope optical axis and the star camera optical axis can be compared and determined in the same reference coordinate system, and coaxiality compensation is performed accordingly. Since the first pointing vector of the telescope optical axis is obtained based on an external reference coordinate system, by introducing an external reference coordinate system independent of the internal structure of the terminal as an external reference, the coaxiality deviation can be avoided from being affected by the deformation of the terminal, thereby realizing accurate calibration of the coaxiality of the on-orbit satellite-borne laser communication terminal.

[0093] Reference Figure 4 As shown in the embodiments of the present specification, in some embodiments of the present specification, obtaining the first pointing vector of the telescope optical axis based on the external reference coordinate system can include the following steps:

[0094] Step 401, obtaining a first position vector of a local star at a specific time based on an external reference coordinate system; the local star is a satellite on which the satellite-borne laser communication terminal is located.

[0095] The external reference coordinate system is an inertial reference frame independent of the satellite-borne laser communication terminal. In some embodiments of the present specification, the external reference coordinate system can be, for example, a J2000 inertial coordinate system, etc. Among them, the J2000 inertial coordinate system takes the center of the Earth as the origin, the reference plane is the equatorial plane of the J2000 epoch, the Z axis points to the north celestial pole, the X axis points to the vernal equinox, and the Y axis completes the right-hand screw rule. This coordinate system is fixed in the star background and is not affected by short-term astronomical phenomena such as Earth rotation or nutation, and can stably maintain the characteristics of the inertial coordinate system.

[0096] In some embodiments of the present specification, the satellite is equipped with a high-precision Global Navigation Satellite System (GNSS) receiver; the satellite can receive signals of navigation satellite systems such as GPS, Beidou, GLONASS or Galileo through the GNSS receiver, and perform multi-satellite positioning based on the J2000 inertial coordinate system, thereby obtaining the position vector at any time. For the local star, it can obtain a first position vector based on the external reference coordinate system at a specific time t; for the target star, it can obtain a second position vector based on the external reference coordinate system at a specific time t. Among them, the target star refers to another satellite carrying another laser communication terminal (as a reference satellite).

[0097] In the embodiments of the present specification, unless otherwise specified, the satellite-borne laser communication terminal generally refers to the satellite-borne laser communication terminal carried on the local star; the telescope and the star camera generally refer to the telescope and the star camera of the satellite-borne laser communication terminal.

[0098] Step 402: Based on the inter-satellite laser link between the local satellite and the target satellite, obtain the second position vector of the target satellite at a specific time based on the external reference coordinate system.

[0099] In some embodiments of this specification, in order to obtain the second position vector of the target star based on the external reference coordinate system, the local satellite can establish an inter-satellite laser link with the target star and conduct inter-satellite laser communication with the target star based on the inter-satellite laser link, thereby obtaining the second position vector of the target star based on the external reference coordinate system at a specific time t.

[0100] Step 403: Determine the position vector difference between the second position vector and the first position vector.

[0101] In some embodiments of this specification, taking the J2000 inertial coordinate system as an example, if the first position vector of the local satellite S at a specific time t based on the J2000 inertial coordinate system is represented as follows: The second position vector of the target star P at a specific time t, based on the J2000 inertial coordinate system, is represented as: The position vector difference between the first position vector and the second position vector can be expressed as: =( x pt - x st , y pt - y st , z pt - z st ) =( x spt , y spt , z spt ).

[0102] in, Let S be the first position vector of this star S at a specific time t based on the J2000 inertial coordinate system; Let t be the second position vector of the target star P at a specific time t based on the J2000 inertial coordinate system; for and Position vector difference; x st , y st , z st for The three-dimensional coordinates based on the J2000 inertial coordinate system at a specific time t. xpt , y pt , z pt for The three-dimensional coordinates based on the J2000 inertial coordinate system at a specific time t; x spt , y spt , z spt for The three-dimensional coordinates based on the J2000 inertial coordinate system at a specific time t.

[0103] Step 404: Determine the position vector difference as the first pointing vector of the telescope optical axis based on the external reference coordinate system at the specific moment.

[0104] The position vector difference between the second position vector and the first position vector precisely represents the direction from the local star to the target star. This is exactly the direction that the optical axis of the telescope of the spaceborne laser communication terminal needs to be aligned with. Therefore, this position vector difference can be determined as the pointing vector of the telescope's optical axis at a specific time t based on the J2000 inertial coordinate system.

[0105] Figure 4 The method shown uses GNSS orbit determination data transmitted via inter-satellite links to calculate the relative position vector (i.e., position vector difference) between the target satellite and the local satellite. Since the J2000 inertial coordinate system and the target satellite are both independent of the local satellite and are not affected by the deformation of the onboard laser communication terminal, the position vector difference, which characterizes the pointing vector of the telescope optical axis at a specific time t based on the J2000 inertial coordinate system, is a highly accurate data, thus laying a high-precision foundation for the entire calibration process.

[0106] refer to Figure 5 As shown, in some other embodiments of this specification, obtaining the first pointing vector of the telescope's optical axis based on an external reference coordinate system may include the following steps:

[0107] Step 501: Obtain the first position vector of the local satellite based on the external reference coordinate system at a specific time; the local satellite is the satellite where the onboard laser communication terminal is located.

[0108] Step 502: Based on the inter-satellite laser link between the local satellite and the target satellite, obtain the second position vector of the target satellite at a specific time based on the external reference coordinate system.

[0109] Step 503: Determine the position vector difference between the second position vector and the first position vector.

[0110] Step 504: Convert the position vector difference into a unit vector.

[0111] In some embodiments of the present specification, the position vector difference can be converted into a unit vector according to the following formula:

[0112]

[0113] wherein, is a unit vector, x spt , y spt , z spt is is a three-dimensional coordinate based on the J2000 inertial coordinate system at a specific time t, x 1spt , y 1spt , z 1spt is is a normalized three-dimensional coordinate based on the J2000 inertial coordinate system at a specific time t.

[0114] Step 505, determining the unit vector as the first pointing vector of the telescope optical axis based on the external reference coordinate system at the specific time.

[0115] Compared with the embodiment shown in Figure 4 , the main difference between the embodiment shown in Figure 5 is that a step of converting the position vector difference into a unit vector is added. Since the unit vector obtained after conversion only represents the direction and does not contain distance information, it makes the subsequent coordinate transformation and angle calculation more efficient and convenient.

[0116] In some embodiments of the present specification, obtaining the second pointing vector of the star camera optical axis of the spaceborne laser communication terminal based on the local reference coordinate system can include: based on the star image captured by the star camera at a specific time, determining the second pointing vector of the star camera based on the star camera coordinate system at the specific time.

[0117] For example, taking the J2000 inertial coordinate system as the external reference coordinate system, under the J2000 inertial coordinate system, the star camera will shoot the space along with the pointing direction of the telescope optical axis to obtain the star image in real time, and then solve the pointing vector of the star camera at a specific time t through the built-in algorithm of the star camera (extracting the image plane coordinates of multiple target stars in the star image for spatial geometric positioning); for example, using the pointing vector represented by the quaternion Q t = [ q 1t , q 2t , q 3t , q 4t ]; wherein,Q t The attitude (including the pointing vector) of the stellar camera at a specific time t can be used to characterize the pointing vector of the stellar camera based on the stellar camera coordinate system at that specific time t; q 1t for Q t The scalar part is related to the rotation angle; q 2t , q 3t , q 4t for Q t The vector portion together defines the direction of the optical axis of the stellar camera.

[0118] refer to Figure 6 As shown, in some embodiments of this specification, transforming the first pointing vector into a third pointing vector in the local reference coordinate system may include the following steps:

[0119] Step 601: Determine the rotation matrix for transforming the external reference coordinate system to the star camera coordinate system at the specific moment based on the quaternion.

[0120] In some embodiments of this specification, it can be based on quaternions Q t The following formula is used to calculate the rotation matrix for transforming the J2000 coordinate system to the star camera coordinate system at a specific time t.

[0121]

[0122] Among them, R JQt This represents the rotation matrix that transforms the J2000 coordinate system to the star camera coordinate system at a specific time t.

[0123] In the embodiments of this specification, the stellar camera coordinate system refers to a three-dimensional (x, y, z) rectangular coordinate system established on the stellar camera body, with the projection center (i.e., optical center) of the stellar camera optical system as the origin.

[0124] Step 602: Multiply the rotation matrix on the right by the first pointing vector to obtain the third pointing vector of the first pointing vector in the star camera coordinate system.

[0125] In some embodiments of this specification, the rotation matrix is ​​right-multiplied by the first pointing vector, which is the result according to the formula. Calculate the pointing vector of the first pointing vector in the star camera coordinate system.

[0126] In some embodiments of this specification, determining the coaxiality deviation of the third pointing vector relative to the second pointing vector may include: determining the azimuth coaxiality deviation of the third pointing vector relative to the second pointing vector (i.e., the coaxiality deviation in the azimuth direction); and determining the pitch coaxiality deviation of the third pointing vector relative to the second pointing vector (i.e., the coaxiality deviation in the pitch direction).

[0127] For example, in Figure 7 In the example shown, in the stellar camera coordinate system, the pointing vector of the telescope's 10 optical axis is as follows: Figure 7 As shown by the dotted line, the pointing vector of the optical axis of the stellar camera 20 is... Figure 7 The double-dotted line is shown in the image. From... Figure 7 As can be seen from this, the elevation angle of the optical axis of telescope 10 is... θ 1 azimuth angle is 1 The pitch angle of the 20 optical axes of the stellar camera is... θ 2 azimuth angle is 2 The azimuth coaxiality deviation between the optical axis of telescope 10 and the optical axis of stellar camera 20 is: θ 2 - θ 1 The azimuth coaxiality deviation between the optical axis of telescope 10 and the optical axis of stellar camera 20 is [missing information]. 2 - 1 .

[0128] In some embodiments of this specification, since the coaxiality deviation between the optical axis of the stellar camera and the optical axis of the telescope is equivalent to a vector... In practical implementation, the coaxiality deviation with respect to the positive Z-axis of the star camera coordinate system can be calculated using the following formulas: azimuth coaxiality deviation and pitch coaxiality deviation.

[0129]

[0130] Where ΔA represents azimuth coaxiality deviation, ΔE represents pitch coaxiality deviation, and y Qt express Q t The projected length along the y-axis in the stellar camera coordinate system, z Qt express Q t The projected length along the z-axis in the stellar camera coordinate system; x Qt express Q t The projected length along the x-axis in the stellar camera coordinate system.

[0131] In some embodiments of the present disclosure, performing the coaxiality compensation according to the coaxiality deviation can include: correcting a terminal pointing algorithm of the spaceborne laser communication terminal according to the azimuth coaxiality deviation and the elevation coaxiality deviation, i.e., compensating the final coaxiality deviation into the terminal pointing algorithm of the spaceborne laser communication terminal, so as to complete the on-orbit calibration of the coaxiality between the optical axis of the star camera and the optical axis of the telescope of the spaceborne laser communication terminal. The terminal pointing algorithm is a set of calculation and control programs configured for the spaceborne laser communication terminal. The main task of the program is to calculate the control instructions (azimuth angle and elevation angle) required for driving the telescope pointing mechanism (such as an azimuth and elevation turntable or a fast steering mirror) according to a given communication target, so as to guide the laser beam to accurately point to the target satellite.

[0132] Reference Figure 8 In some embodiments of the present disclosure, the on-orbit calibration method of the coaxiality of the spaceborne laser communication terminal can include the following steps:

[0133] Step 801: obtaining a first pointing vector of a telescope optical axis of a spaceborne laser communication terminal based on an external reference coordinate system.

[0134] Step 802: obtaining a second pointing vector of a star camera optical axis of the spaceborne laser communication terminal based on a local reference coordinate system.

[0135] Step 803: transforming the first pointing vector into a third pointing vector in the local reference coordinate system.

[0136] Step 804: determining a coaxiality deviation of the third pointing vector relative to the second pointing vector.

[0137] Step 805: obtaining coaxiality deviations of the telescope optical axis and the star camera optical axis at multiple different times.

[0138] Step 806: determining a central tendency value of the coaxiality deviations at the multiple different times.

[0139] In a theoretical case, the coaxiality deviation between the star camera optical axis and the telescope optical axis is slowly varying, so that the coaxiality deviations of the telescope optical axis and the star camera optical axis at multiple different times (for example, multiple different times with equal sampling time intervals) can be obtained within a continuous time period, which is beneficial to eliminate systematic errors and random errors, thereby improving the accuracy of the coaxiality calibration.

[0140] In some embodiments of the present disclosure, the central tendency value can be an average value (such as an arithmetic mean, etc.), a median, a mode, etc. For example, taking the arithmetic mean as an example, the azimuth and elevation coaxiality deviations (ΔA1, ΔA2, …, ΔA n ), and the elevation coaxiality deviations (ΔE1, ΔE2, …, ΔE n ) of the optical axis of the telescope and the optical axis of the star camera at multiple different time points (t0, t1, …, tn) with equal sampling time intervals within a continuous time period can be obtained, and then the arithmetic mean thereof is calculated, respectively. n

[0141] In some embodiments of the present disclosure, before determining the central tendency value of the coaxiality deviations at the multiple different time points, outliers (wild values) in the coaxiality deviations at the multiple different time points can also be removed to avoid affecting the accuracy of the coaxiality calibration.

[0142] For example, in an exemplary embodiment of the present disclosure, the following method can be used to remove outliers in the azimuth and elevation coaxiality deviations at the multiple different time points.

[0143] (1) If ΔA i satisfies , then ΔA i is removed, otherwise it is retained, wherein σ is a threshold value that can be set according to actual conditions; ΔA i is the ith azimuth coaxiality deviation in ΔA1, ΔA2, …, ΔA n ; and n is the number of azimuth coaxiality deviations.

[0144] (2) If ΔE i satisfies , then ΔE i is removed, otherwise it is retained, wherein σ is a threshold value that can be set according to actual conditions; ΔE i is the ith elevation coaxiality deviation in ΔE1, ΔE2, …, ΔE n ; and n is the number of elevation coaxiality deviations.

[0145] Step 807: correcting the terminal pointing algorithm of the spaceborne laser communication terminal according to the central tendency value.

[0146] Compared with the embodiment shown in Figure 3 , the embodiment shown in Figure 8 can further improve the accuracy of the coaxiality calibration by removing outliers in multiple samplings within a continuous time period, and using the central tendency value of the sampling values after removing the outliers to correct the corresponding parameter value in the terminal pointing algorithm of the spaceborne laser communication terminal.

[0147] ​Corresponding to the on-orbit calibration of coaxiality of the spaceborne laser communication terminal described above, the embodiments of the present specification further provide an on-orbit calibration device of coaxiality of a spaceborne laser communication terminal, as shown in the Figure 9 In some embodiments of the present specification, the on-orbit calibration device of coaxiality of a spaceborne laser communication terminal can include:

[0148] The first acquisition module 91 is configured to acquire a first pointing vector of a telescope optical axis of a spaceborne laser communication terminal based on an external reference coordinate system;

[0149] The second acquisition module 92 is configured to acquire a second pointing vector of a star camera optical axis of the spaceborne laser communication terminal based on a local reference coordinate system;

[0150] The vector transformation module 93 is configured to transform the first pointing vector into a third pointing vector in the local reference coordinate system;

[0151] The deviation determination module 94 is configured to determine a coaxiality deviation of the third pointing vector relative to the second pointing vector;

[0152] The deviation compensation module 95 is configured to perform coaxiality compensation according to the coaxiality deviation.

[0153] The embodiments of the present application further provide a spaceborne laser communication terminal, which can perform the on-orbit calibration method of coaxiality described above. In some embodiments of the present application, the spaceborne laser communication terminal may, for example, be a base station with laser communication function, but the present application is not limited thereto, and can also be other network devices.

[0154] Figure 10 As shown in the constituent schematic diagram of the spaceborne laser communication terminal of the embodiments of the present application. As shown in the Figure 10 The spaceborne laser communication terminal 1000 can include a processor 1010 (such as a central processing unit CPU) and a memory 1020; the memory 1020 is coupled to the processor 1010. The memory 1020 can store various data; in addition, it also stores the program 1030 of information processing, and executes the program 1030 under the control of the processor 1010.

[0155] For example, the processor 1010 can be configured to execute a program to implement the on-orbit calibration method of coaxiality of a spaceborne laser communication terminal as described in the foregoing embodiments. For example, the processor 1010 can be configured to perform control to: acquire a first pointing vector of a telescope optical axis of a spaceborne laser communication terminal based on an external reference coordinate system; acquire a second pointing vector of a star camera optical axis of the spaceborne laser communication terminal based on a local reference coordinate system; transform the first pointing vector into a third pointing vector in the local reference coordinate system; determine a coaxiality deviation of the third pointing vector relative to the second pointing vector; and perform coaxiality compensation according to the coaxiality deviation.

[0156] In addition, as shown in Figure 10 The spaceborne laser communication terminal 1000 can also include a transceiver 1040 and an antenna 1050, etc. The functions of the above components are similar to those in the prior art, and thus are not described here. It is worth noting that the spaceborne laser communication terminal 1000 does not necessarily include all the components shown in Figure 10 In addition, the spaceborne laser communication terminal 1000 can also include components not shown in Figure 10 In addition, the spaceborne laser communication terminal 1000 can also include components not shown in

[0157] The embodiments of the present application also provide a chip, wherein the chip includes circuitry configured to perform the on-orbit calibration method of coaxiality of a spaceborne laser communication terminal described above.

[0158] For ease of description, the above apparatus is described in various units by function. Of course, the functions of each unit can be implemented in one or more software and / or hardware in the implementation of the present application.

[0159] The embodiments of the present application also provide a computer storage medium, which stores instructions, wherein the instructions, when executed by at least one processor of a computer device alone or in combination, cause the computer device to perform the on-orbit calibration of coaxiality of a spaceborne laser communication terminal.

[0160] The embodiments of the present application also provide a computer program product, which includes instructions, wherein the instructions, when executed by at least one processor of a computer device alone or in combination, cause the computer device to perform the on-orbit calibration of coaxiality of a spaceborne laser communication terminal.

[0161] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 one or more flow or blocks Figure 1 means for functionally implementing the steps in one or more flow or blocks

[0162] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 one or more flow or blocks Figure 1 means for functionally implementing the steps in one or more flow or blocks

[0163] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 one or more flow or blocks Figure 1 Figure 1 means for functionally implementing the steps in one or more flow or blocks

[0164] In one typical configuration, the computer device includes one or more processors (CPU's), input / output interfaces, network interfaces, and memory.

[0165] The memory can include non-persistent memory and / or persistent memory, both of which can be volatile and / or non-volatile. Non-persistent memory can be, for example, random access memory (RAM), and non-volatile memory can be, for example, read-only memory (ROM), flash memory, or a combination thereof. The memory is an example of computer-readable media.

[0166] Computer-readable media includes permanent and non-permanent, movable and non-movable media, which can be implemented by any method or technology to store information. The information can be computer-readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassette, magnetic disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information accessible by a computer device. According to the definition in this application, computer-readable media does not include transitory media such as modulated data signals and carriers.

[0167] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system or a computer program product. Therefore, the embodiments of the present application can take the form of a complete hardware embodiment, a complete software embodiment or an embodiment combining software and hardware aspects. Moreover, the embodiments of the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0168] The embodiments of the present application can be described in the general context of computer-executable instructions executed by a computer, such as program modules. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. The embodiments of the present application can also be practiced in distributed computing environments where tasks are performed by remote processing devices connected by a communication network. In a distributed computing environment, program modules can be located in both local and remote computer storage media including storage devices.

[0169] It should also be understood that in the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, which means that there can be three relationships. For example, A and / or B can mean that A exists alone, A and B exist together, and B exists alone. In addition, the character " / " in this paper generally means that the associated objects before and after are in an "or" relationship.

[0170] The various embodiments in the present application are described in a progressive manner, and the same or similar parts among the various embodiments can be referred to each other. Each embodiment focuses on the difference from other embodiments. In particular, the system embodiments are described simply because they are basically similar to the method embodiments, and the relevant parts can be referred to the description of the method embodiments.

[0171] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present application, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any suitable manner in any one or more embodiments or examples. In addition, the person skilled in the art can combine and combine the different embodiments or examples described in the present application and the features of the different embodiments or examples without contradiction.

[0172] The above only describes the embodiments of the present application and is not intended to limit the present application. The present application can have various modifications and changes for those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the scope of claims of the present application.

Claims

1. A coaxiality on-orbit calibration method of a spaceborne laser communication terminal, characterized in that, The method comprises: obtaining a first pointing vector of a telescope optical axis of a spaceborne laser communication terminal based on an external reference coordinate system, comprising: obtaining a first position vector of a home star at a specific time based on the external reference coordinate system; the home star is a satellite where the spaceborne laser communication terminal is located; obtaining a second position vector of a target star at the specific time based on the external reference coordinate system based on an interstellar laser link between the home star and the target star; determining a position vector difference between the second position vector and the first position vector; determining the position vector difference as a first pointing vector of the telescope optical axis at the specific time based on the external reference coordinate system; obtaining a second pointing vector of a star camera optical axis of the spaceborne laser communication terminal based on a local reference coordinate system; transforming the first pointing vector into a third pointing vector in the local reference coordinate system; determining a coaxial degree deviation of the third pointing vector relative to the second pointing vector; performing coaxial degree compensation according to the coaxial degree deviation.

2. The coaxiality on-orbit calibration method of claim 1, wherein, After determining the position vector difference between the second position vector and the first position vector, further comprising: converting the position vector difference into a unit vector; determining the unit vector as the first pointing vector of the telescope optical axis at the specific time based on the external reference coordinate system.

3. The coaxiality on-orbit calibration method of claim 1, wherein, The method of obtaining the second pointing vector of the star camera optical axis of the spaceborne laser communication terminal based on the local reference coordinate system comprises: determining the second pointing vector of the star camera at the specific time based on the star camera coordinate system based on a star image captured by the star camera at the specific time.

4. The coaxiality on-orbit calibration method of claim 3, wherein, The second pointing vector is represented based on a quaternion.

5. The coaxiality on-orbit calibration method of claim 4, wherein, The method of transforming the first pointing vector into the third pointing vector in the local reference coordinate system comprises: determining a rotation matrix of the external reference coordinate system transformed to the star camera coordinate system at the specific time according to the quaternion; right multiplying the rotation matrix by the first pointing vector to obtain the third pointing vector of the first pointing vector in the star camera coordinate system.

6. The coaxiality on-orbit calibration method of claim 1, wherein, The method of determining the coaxial degree deviation of the third pointing vector relative to the second pointing vector comprises: determining an azimuth coaxial degree deviation of the third pointing vector relative to the second pointing vector; and determining a pitch coaxial degree deviation of the third pointing vector relative to the second pointing vector.

7. The coaxiality on-orbit calibration method of claim 6, wherein, The method of performing coaxial degree compensation according to the coaxial degree deviation comprises: correcting a terminal pointing algorithm of the spaceborne laser communication terminal according to the azimuth coaxial degree deviation and the pitch coaxial degree deviation.

8. The coaxiality on-orbit calibration method of claim 1, wherein, After determining the coaxial degree deviation of the third pointing vector relative to the second pointing vector, further comprising: obtaining coaxial degree deviations of the telescope optical axis and the star camera optical axis at multiple different times; determining a concentration value of the coaxial degree deviations at the multiple different times; correspondingly, the method of performing coaxial degree compensation according to the coaxial degree deviation comprises: correcting a terminal pointing algorithm of the spaceborne laser communication terminal according to the concentration value.

9. The coaxiality on-orbit calibration method of claim 8, wherein, Before determining the concentration value of the coaxial degree deviations at the multiple different times, further comprising: Outliers in the plurality of coaxiality deviations at different time instants are removed.

10. The coaxiality on-orbit calibration method of claim 1, wherein, The external reference coordinate system comprises a J2000 inertial coordinate system.

11. An on-orbit calibration device for coaxiality of a spaceborne laser communication terminal, characterized in that, The method comprises: The first acquisition module is configured to acquire a first pointing vector of a telescope optical axis of the spaceborne laser communication terminal based on an external reference coordinate system, comprising: acquiring a first position vector of a home star at a specific time based on an external reference coordinate system; the home star is a satellite on which the spaceborne laser communication terminal is located; based on an interstellar laser link between the home star and a target star, acquiring a second position vector of the target star at the specific time based on the external reference coordinate system; determining a position vector difference between the second position vector and the first position vector; determining the position vector difference as the first pointing vector of the telescope optical axis at the specific time based on the external reference coordinate system; The second acquisition module is configured to acquire a second pointing vector of a star camera optical axis of the spaceborne laser communication terminal based on a local reference coordinate system; The vector transformation module is configured to transform the first pointing vector into a third pointing vector in the local reference coordinate system; The deviation determination module is configured to determine a coaxiality deviation of the third pointing vector relative to the second pointing vector; The deviation compensation module is configured to perform coaxiality compensation according to the coaxiality deviation.

12. A space-borne laser communication terminal, characterized by The method comprises: at least one processor; and at least one memory storing instructions thereon, which, when executed by the at least one processor alone or collectively, cause the spaceborne laser communication terminal to perform the method according to any one of claims 1 to 10.

13. A computer storage medium having stored thereon instructions, the computer storage medium comprising: The instructions, when executed by the at least one processor of the computer device alone or collectively, cause the computer device to perform the method according to any one of claims 1 to 10.

14. A computer program product comprising instructions, characterized in that, The instructions, when executed by the at least one processor of the computer device alone or collectively, cause the computer device to perform the method according to any one of claims 1 to 10.

15. A chip, characterized by The chip comprises circuitry configured to perform the method according to any one of claims 1 to 10.

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