A method and system for acquiring satellite attitude at exposure time

Abstract

The present invention provides a method and system for acquiring satellite attitude at the exposure time, which relates to the field of data processing technology. The method comprises: acquiring satellite attitude quaternion with timestamp; collecting exposure image and exposure image timestamp; performing linear interpolation on satellite attitude quaternion to acquire satellite attitude synchronization quaternion of exposure image at the exposure image timestamp; calculating satellite rotation matrix in geocentric coordinate system according to satellite attitude synchronization quaternion; calculating scanning mirror correction rotation angle including scanning mirror rotation error of the previous scanning cycle; calculating sight vector rotation matrix of satellite infrared payload equipment under scanning mirror correction rotation angle; combining sight vector rotation matrix and satellite rotation matrix in geocentric coordinate system to calculate equivalent matrix of satellite attitude, and obtain satellite attitude at the exposure time. The influence of satellite data transmission and satellite structure on satellite attitude at the exposure time is reduced, and the accuracy of satellite attitude corresponding to exposure image is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of data processing, and in particular to a method and system for acquiring satellite attitude at the exposure moment. Background Art

[0002] The satellite attitude at the moment of exposure refers to the spatial orientation of the satellite at the exact moment of capturing images or collecting other types of sensor data, that is, the star-sensing quaternion and coordinate sequence data parsed from the original data of the infrared payload. These data are determined by the GPS device of the satellite platform and transmitted to the original data through the infrared transmission protocol at a preset frequency. The scanning image takes multiple images including black body images within a certain period of time. Therefore, although the auxiliary package of each scanning image in the original data contains attitude and orbit information, they are not all valid, and because their counting devices and the counting of the infrared payload are not able to accurately correspond.

[0003] Satellite attitude determines the geometric relationship between the sensor on the satellite and the earth's surface or the observed target, which directly affects the accuracy and quality of the data. The satellite attitude determines the direction of the sensor's field of view. Incorrect attitude may lead to geolocation errors, which will affect subsequent data analysis and applications such as mapping, resource exploration or environmental monitoring. If the attitude control is not precise, it may cause blurred images or the coverage area to deviate from the target area. Especially for earth observation missions that require high resolution and high precision, consistent and accurate attitude records ensure that the images can be properly aligned for accurate comparison.

[0004] However, at present, the satellite attitude uploaded by GPS and received by the satellite infrared payload is often directly used as the satellite attitude at the exposure time. This results in inaccurate satellite attitude recorded in each exposure image, which in turn makes it impossible to accurately locate the ground coordinates of the exposure image, which directly leads to large errors in various tasks based on the exposure image. Summary of the invention

[0005] In order to solve the technical problem that the satellite attitude uploaded by GPS and received by the satellite infrared payload is often directly used as the satellite attitude at the exposure time in the prior art, which results in inaccurate satellite attitude recorded in each exposure image, and further causes the exposure image to be unable to accurately locate the ground coordinates, which directly leads to large errors in various tasks performed based on the exposure image, the present invention provides a method and system for obtaining the satellite attitude at the exposure time.

[0006] The technical solution provided by the embodiment of the present invention is as follows:

[0007] First aspect

[0008] An embodiment of the present invention provides a method for acquiring a satellite attitude at an exposure time, comprising:

[0009] S1: Get satellite attitude quaternion with timestamp;

[0010] S2: Collect exposure images and exposure image timestamps;

[0011] S3: perform linear interpolation on the satellite attitude quaternion to obtain the satellite attitude synchronization quaternion of the exposure image at the exposure image timestamp;

[0012] S4: Calculate the satellite rotation matrix in the geocentric coordinate system based on the satellite attitude synchronization quaternion;

[0013] S5: Calculating a scanning mirror correction rotation angle including a scanning mirror rotation error of a previous scanning cycle, wherein the scanning mirror is used to collect an exposure image;

[0014] S6: Calculate the sight vector rotation matrix of the satellite infrared payload equipment under the corrected rotation angle of the scanning mirror;

[0015] S7: Combine the line of sight vector rotation matrix and the satellite rotation matrix in the geocentric coordinate system to calculate the equivalent matrix of the satellite attitude and obtain the satellite attitude at the exposure time.

[0016] Second aspect

[0017] An embodiment of the present invention provides a system for acquiring satellite attitude at exposure time, comprising:

[0018] processor;

[0019] A memory having computer-readable instructions stored thereon, wherein when the computer-readable instructions are executed by the processor, the method for acquiring the satellite attitude at the exposure moment as described in the first aspect is implemented.

[0020] The beneficial effects brought about by the technical solution provided by the embodiment of the present invention include at least:

[0021] In the present invention, the satellite attitude quaternion representing the satellite attitude synchronized to the GPS is first obtained, and then the accurate attitude quaternion of each exposure image is obtained with a unified timestamp as the interpolation element, and the satellite rotation matrix in the geocentric coordinate system is established based on the satellite attitude quaternion to facilitate the attitude description of the satellite attitude, and then, considering the rotation error of the satellite scanning mirror and the influence of the rotation of the satellite scanning mirror on the line of sight of the infrared payload equipment, the satellite rotation matrix is ​​corrected to obtain an equivalent matrix that can accurately represent the satellite attitude, and then the satellite attitude under each exposure image is accurately obtained, and the influence of satellite data transmission and satellite structure on the satellite attitude at the exposure time is reduced, so as to accurately locate the ground coordinates corresponding to each exposure image and improve the satellite working quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0023] Figure 1 A schematic diagram of a flow chart of a method for acquiring satellite attitude at the exposure moment provided by an embodiment of the present invention;

[0024] Figure 2 A schematic diagram of the structure of a track coordinate system provided by an embodiment of the present invention;

[0025] Figure 3 A schematic diagram of a flow chart of another orbital coordinate system provided by an embodiment of the present invention;

[0026] Figure 4 A schematic diagram of the structure of a satellite attitude acquisition system at the exposure moment provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0027] The technical solution of the present invention is described below in conjunction with the accompanying drawings.

[0028] In the embodiments of the present invention, words such as "exemplarily" and "for example" are used to indicate examples, illustrations or explanations. Any embodiment or design described as "example" in the present invention should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of the word "example" is intended to present the concept in a specific way. In addition, in the embodiments of the present invention, the meaning expressed by "and / or" can be both, or it can be either of the two.

[0029] In the embodiments of the present invention, "image" and "picture" can sometimes be used interchangeably. It should be noted that when the difference between them is not emphasized, the meanings they intend to express are the same. "of", "corresponding, relevant" and "corresponding" can sometimes be used interchangeably. It should be noted that when the difference between them is not emphasized, the meanings they intend to express are the same.

[0030] In the embodiments of the present invention, sometimes a subscript such as W1 may be mistakenly written as a non-subscript such as W1. When the difference is not emphasized, the meanings to be expressed are consistent.

[0031] In order to make the technical problems, technical solutions and advantages to be solved by the present invention more clear, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0032] Reference Manual Attached Figure 1, shows a flow chart of a method for acquiring satellite attitude at the exposure moment provided by an embodiment of the present invention.

[0033] The embodiment of the present invention provides a method for acquiring satellite attitude at the exposure time, which can be implemented by a device for acquiring satellite attitude at the exposure time, and the device for acquiring satellite attitude at the exposure time can be a terminal or a server. The processing flow of the method for acquiring satellite attitude at the exposure time may include the following steps:

[0034] S1: Get satellite attitude quaternion with timestamp.

[0035] Among them, the timestamp refers to the specific moment recorded, usually accurate to seconds or milliseconds. In a space mission, each data point (such as attitude data) requires a timestamp to facilitate accurate synchronization with other events or data. The timestamp ensures the temporal order and accuracy of the data, allowing accurate tracking and playback of events. The satellite attitude quaternion is a mathematical tool used to represent the attitude of an object in three-dimensional space. It consists of a real part and three imaginary parts. The accurate recording of timestamps and satellite attitude quaternions is the basis for ensuring that the satellite can effectively perform its mission and collect high-quality data.

[0036] In a possible implementation, the satellite attitude quaternion is acquired through a star sensor of the satellite, and the timestamp of the satellite attitude quaternion is synchronized through a GPS positioning system.

[0037] It should be noted that the GPS positioning system can also synchronize satellite coordinate information and satellite platform speed information. For each exposure image, interpolation is also required to obtain accurate coordinate information and speed information.

[0038] S2: Collect exposure images and exposure image timestamps.

[0039] Among them, exposure images refer to image data of the ground or other targets captured by satellite sensors. Each exposure image is marked with a timestamp, which records the exact moment when the image was captured. The basis for satellite remote sensing data acquisition ensures that each image obtained has an exact time stamp, providing a basis for subsequent data processing and application.

[0040] S3: Linearly interpolate the satellite attitude quaternion to obtain the satellite attitude synchronization quaternion of the exposure image at the exposure image timestamp.

[0041] Among them, linear interpolation is a basic interpolation technique used to estimate the value of the middle point between two known data points. Linear interpolation of satellite attitude quaternions aims to obtain satellite attitude quaternions that accurately match the timestamp of a specific exposure image. This step is crucial in ensuring the synchronization of image data and attitude data, especially when the acquisition frequency of satellite attitude data is not completely consistent with the image capture frequency. Linear interpolation can effectively synchronize the satellite's attitude data with the specific image capture moment, which is crucial for high-precision ground positioning, image correction and subsequent analysis, ensuring the continuity and consistency of satellite data.

[0042] For example, the attitude matrix and platform coordinates at the time of exposure can accurately determine where the satellite lens is pointing on the earth's surface, thereby accurately mapping the image to the ground coordinate system. Attitude and orbit data refers to the star-sensing quaternion and coordinate sequence data parsed from the original data of the infrared payload. These data are determined by the GPS device of the satellite platform and transmitted to the original data through the infrared transmission protocol at a frequency of once per second. The scanning image takes 25 images including the black body image in 15.6 seconds, which means that the satellite attitude data synchronized by GPS received by each exposure image cannot accurately correspond to the GPS transmission frequency, because 25 images are collected in 15.6 seconds, not one per second. Therefore, although the auxiliary package of each scanned image in the original data contains attitude and orbit information, they are not all valid, and because the counting device and the infrared payload count cannot accurately correspond, it is necessary to perform spherical linear interpolation on the star-sensing attitude quaternion of each image, and calculate the attitude quaternion and coordinate position that strictly corresponds to the image exposure time through interpolation.

[0043] In a possible implementation, S3 specifically includes:

[0044] S301: Create a first linked list of satellite attitude quaternions and a second linked list of satellite attitude quaternions marked by exposure images, wherein each satellite attitude quaternion in each linked list has a corresponding timestamp.

[0045] S302: Searching in the first linked list for two timestamps adjacent to the timestamp of the satellite attitude quaternion marked by the exposure image.

[0046] S303: Linearly interpolate the timestamp of the satellite attitude quaternion marked by the exposure image according to the time interval between two adjacent timestamps to obtain the satellite attitude quaternion corresponding to the timestamp of the satellite attitude quaternion marked by the exposure image.

[0047] Specifically, when interpolating the attitude and track data, two linked lists need to be created. Linked list list1 contains the attitude and track data type objects sent by the satellite platform GPS device at a frequency of once per second, and linked list list2 contains the attitude and track data divided according to one cycle of images. Both linked lists contain the timestamp information corresponding to the respective attitude and track data. Before interpolation, the attitude and track information in the attitude and track data linked list AttiCoordList1 at the moment of image exposure is assigned to the default value, and then for each element in AttiCoordList1, the two attitude and track data with the closest distance before and after its timestamp are found in list2, and the linear interpolation method is used to interpolate it according to the time interval between the two GPS before and after.

[0048] It should be noted that the use of two linked lists for linear interpolation of satellite attitude quaternions and the creation of two linked lists with timestamps can ensure that the data sorting and retrieval process is efficient and orderly. It allows the specific moment of the exposure image to be accurately matched with the closest satellite attitude data, thereby improving the timeliness and accuracy of the attitude data. At the same time, the use of linear interpolation to estimate the attitude at the exposure moment between the two closest time points can provide continuous and smooth attitude estimation in data recording gaps or asynchronous data collection. This interpolation method is simple and efficient, and can quickly obtain the required attitude information without adding too much computational burden, which is particularly important for time-sensitive remote sensing tasks, ensuring the reliability of the data and the real-time nature of the operation.

[0049] S4: Calculate the satellite rotation matrix in the geocentric coordinate system based on the satellite attitude synchronization quaternion.

[0050] The satellite rotation matrix is ​​a 3x3 orthogonal matrix that describes the spatial rotation of the satellite relative to a reference coordinate system (such as the geocentric inertial coordinate system or the J2000 coordinate system). This matrix intuitively represents the transformation from the satellite's body coordinate system (a coordinate system fixed to the satellite and rotating with the satellite) to the reference coordinate system (a fixed external coordinate system). The main advantage of the rotation matrix is ​​its ability to be directly applied to vectors. For example, if you need to determine the orientation of a sensor on a satellite relative to the earth's surface, you can use this rotation matrix to transform the orientation of the sensor in the satellite's body coordinate system to the orientation in the geocentric coordinate system. In addition, rotation matrices are also very useful in visualizing, simulating, and analyzing satellite motion because they can be directly combined with other matrix and vector operations to provide intuitive information about the satellite's motion and orientation.

[0051] In a possible implementation, S4 specifically includes:

[0052] S401: Calculate the satellite rotation matrix in the J2000 inertial coordinate system based on the satellite attitude synchronization quaternion:

[0053]

[0054] Among them, R′ represents the satellite rotation matrix in the J2000 inertial coordinate system, and q0, q1, q2, and q3 represent the scalar, x-axis component, y-axis component, and z-axis component in the satellite attitude synchronization quaternion, respectively.

[0055] S402: Perform coordinate system transformation on the satellite rotation matrix in the J2000 inertial coordinate system to obtain the satellite rotation matrix in the geocentric coordinate system.

[0056] It should be noted that the method of calculating and converting the satellite rotation matrix provides the ability to accurately describe the satellite's spatial attitude in different coordinate systems. First, the satellite's rotation matrix is ​​calculated in the J2000 inertial coordinate system to ensure a stable and accurate attitude description, because J2000 is a widely recognized and used astronomical coordinate standard that provides a reference that is independent of the earth's rotation. Then, this matrix is ​​converted to the geocentric coordinate system, allowing the data to be directly connected to earth-related observations and applications, such as ground tracking and satellite navigation. This method enhances the practicality and interoperability of satellite data, making satellite operations more precise and meeting the actual needs of earth observation.

[0057] S5: Calculating a corrected rotation angle of a scanning mirror including a rotation error of the scanning mirror in a previous scanning cycle, wherein the scanning mirror is used to collect an exposure image.

[0058] Among them, the scanning cycle refers to the time period required for the scanning mirror to complete a complete scan, which includes the time from the start to the end of scanning a ground track. During a complete scanning cycle, the scanning mirror will move according to a predetermined pattern (such as linear scanning, retrace, etc.) to ensure that the target area is completely covered.

[0059] It should be noted that the scanning mirror may have positioning errors during operation. This error may be caused by a variety of factors, such as mechanical wear, temperature changes affecting the shape or elasticity of the material, and slight deviations in the electronic control system. These errors will affect the accuracy of the image's geographic positioning and the quality of the image. In order to compensate for the positioning error of the scanning mirror and ensure the accuracy of the data, the rotation angle of the scanning mirror needs to be corrected. The satellite attitude equivalent matrix is ​​also affected by the swing angle of the plane scanning mirror carried by the satellite. Therefore, it is necessary to accurately obtain the rotation angle of the scanning mirror under each exposure image. This method is used to correct the rotation angle of the scanning mirror in each scanning cycle, which can effectively avoid error accumulation and obtain the accurate rotation angle of the scanning mirror for each exposure image.

[0060] In a possible implementation manner, the scanning mirror correction rotation angle is specifically:

[0061]

[0062] Δa=ΔA / m

[0063] θ i '=θ i +Δa

[0064] Where m represents the number of exposure images collected in one scanning cycle, θ i represents the rotation angle of the scanning mirror when the i-th exposure image is collected in the previous scanning cycle, ΔA represents the total error of the scanning cycle, Δa represents the rotation angle error of the scanning mirror in each scan, and θ i ' represents the scanning mirror rotation angle when acquiring the i-th exposure image in the current scanning cycle, that is, the scanning mirror correction rotation angle.

[0065] For example, the scanning mirror needs to take 25 images in each scanning cycle, and the rotation angle corresponding to each image is given by the angle measurement device. However, there will always be some errors due to various reasons during the rotation process, so a zero-return strategy is used to record the deflection angle of the scanning mirror when the scanning mirror rotates for one cycle. Ideally, the angle of the zero-return device should be the position where the scanning mirror rotates 360 degrees. By obtaining the numerical difference between the angle measurement value of the device and 360 degrees, the total rotation error of the scanning mirror in the entire scanning cycle is obtained, and each angle is corrected according to the closure error. In this way, the rotation angle error of the current scanning mirror is avoided.

[0066] S6: Calculate the sight vector rotation matrix of the satellite infrared payload equipment under the corrected rotation angle of the scanning mirror.

[0067] Among them, satellite infrared payload equipment refers to instruments installed on satellites for capturing infrared radiation. This type of equipment can detect and measure infrared radiation from the surface, atmosphere or other celestial bodies, and is usually used in environmental monitoring, meteorological observation, agricultural analysis, military applications and other fields. According to its design, infrared payload equipment can distinguish infrared radiation of different wavelengths to obtain information about the temperature, humidity, chemical composition and other aspects of the object. The line of sight vector rotation matrix describes how the observation direction of a specific sensor on the satellite (such as infrared payload equipment) changes with the adjustment of the scanning mirror. This matrix mainly reflects how the line of sight of the sensor (i.e., the direction from the sensor to the observed target) rotates in space due to the rotation of the scanning mirror. Changes in the correction rotation angle of the scanning mirror will cause changes in the line of sight of the infrared payload equipment. Considering this factor can increase the accuracy and reliability of the acquired satellite attitude.

[0068] In a possible implementation, the sight vector rotation matrix is ​​specifically:

[0069]

[0070] Where R3 represents the sight vector rotation matrix, θ = θ′ i Indicates the corrected rotation angle of the scanning mirror when acquiring the i-th exposure image in the current scanning cycle.

[0071] S7: Combine the line of sight vector rotation matrix and the satellite rotation matrix in the geocentric coordinate system to calculate the equivalent matrix of the satellite attitude and obtain the satellite attitude at the exposure time.

[0072] Among them, the satellite rotation matrix describes the spatial orientation of the entire satellite relative to the geocentric coordinate system, which includes the positioning and attitude of the satellite around the earth. The purpose of combining the line of sight vector rotation matrix and the satellite rotation matrix is ​​to create a comprehensive equivalent matrix that can simultaneously reflect the influence of the scanning mirror adjustment and the overall attitude of the satellite. The equivalent matrix obtained can be directly used to calculate the exact pointing direction of the satellite sensor to ensure the accurate geographic positioning of the observation data. It is also used in mission planning and data processing to ensure that all remote sensing data corresponds correctly to geographic features. The accurate satellite attitude at the exposure time is then obtained, which further ensures the accurate correspondence between the exposure image and the ground coordinates, and improves the accuracy of satellite data acquisition.

[0073] In a possible implementation, the equivalent matrix is ​​specifically:

[0074]

[0075] Among them, R represents the equivalent matrix, and R2 represents the installation matrix of the infrared payload in the satellite, namely the internal orientation element.

[0076] It should be noted that by combining the satellite's infrared payload installation matrix with the attitude matrix, a comprehensive conversion tool is provided, which reflects the precise spatial positioning and orientation of specific equipment inside the satellite (such as infrared payload) relative to the outside world (such as the earth or celestial body). The satellite's attitude data can be directly applied to accurately control and correct the direction of the payload, thereby enhancing the accuracy and reliability of the observation data. In this way, any deviation caused by installation errors or changes in the equipment can be effectively corrected, ensuring that the remote sensing data obtained from the satellite is optimal in quality and accuracy.

[0077] Reference Manual Attached Figure 2 , shows a schematic structural diagram of a track coordinate system provided by an embodiment of the present invention.

[0078] Reference Manual Attached Figure 3 , shows a schematic flow chart of another orbital coordinate system provided in an embodiment of the present invention.

[0079] In a possible implementation, it further includes:

[0080] S8: Establish an orbital coordinate system with the satellite's center of mass as the origin, and use the orbital coordinate system to describe the satellite's attitude, that is, the satellite's attitude at the exposure time.

[0081] Among them, the orbital coordinate system is a coordinate system with the satellite's center of mass as the origin and moves as the satellite moves in orbit. This coordinate system is usually directly related to the satellite's orbital elements (such as the orbital plane and the direction of motion) and is used to describe the satellite's position and attitude relative to the earth. The main purpose of establishing an orbital coordinate system and using it to describe the satellite's attitude is to provide an intuitive and practical way to monitor and control the satellite's spatial position and orientation relative to the earth.

[0082] In a possible implementation, S8 specifically includes:

[0083] S801: Synchronize satellite speed and satellite position through GPS positioning system.

[0084] S802: Obtain the satellite velocity vector and satellite position vector in the geocentric coordinate system.

[0085] S803: Combine the satellite velocity vector and the satellite position vector to establish an orbital coordinate system. The Z axis of the orbital coordinate system points from the origin, i.e., the satellite mass center, to the center of the earth. The unit vector of the orbital coordinate system on each coordinate axis is:

[0086]

[0087] Among them, x0, y0, z0 represent the X-axis unit vector, Y-axis unit vector and Z-axis unit vector of the orbital coordinate system respectively, r represents the satellite position vector, v represents the satellite velocity vector, and || represents taking the absolute value.

[0088] S804: Describe the satellite attitude, ie, the satellite attitude at the exposure time, by using the orbital coordinate system.

[0089] It should be noted that the speed and position information of the satellite is obtained through the GPS positioning system, and then these data are used to establish an orbital coordinate system. In this coordinate system, the Z axis points to the center of the earth, that is, from the satellite's center of mass to the center of the earth, while the X axis and Y axis are defined according to the direction and position of the satellite's movement to ensure the orthogonality and right-handedness of the coordinate system. This orbital coordinate system is crucial for accurately describing the attitude of the satellite in orbit, because it directly reflects the specific direction of the satellite relative to the earth, which is the basis for adjusting the satellite's observation equipment, conducting precise navigation, and performing scientific tasks. The orbital coordinate system is used to describe the attitude of the satellite at a specific exposure time to ensure the accuracy of data capture and the geographic calibration of remote sensing images.

[0090] The beneficial effects brought about by the technical solution provided by the embodiment of the present invention include at least:

[0091] In the present invention, the satellite attitude quaternion representing the satellite attitude synchronized to the GPS is first obtained, and then the accurate attitude quaternion of each exposure image is obtained with a unified timestamp as the interpolation element, and the satellite rotation matrix in the geocentric coordinate system is established based on the satellite attitude quaternion to facilitate the attitude description of the satellite attitude, and then, considering the rotation error of the satellite scanning mirror and the influence of the rotation of the satellite scanning mirror on the line of sight of the infrared payload equipment, the satellite rotation matrix is ​​corrected to obtain an equivalent matrix that can accurately represent the satellite attitude, and then the satellite attitude under each exposure image is accurately obtained, and the influence of satellite data transmission and satellite structure on the satellite attitude at the exposure time is reduced, so as to accurately locate the ground coordinates corresponding to each exposure image and improve the satellite working quality.

[0092] Reference Manual Attached Figure 4 , showing a schematic structural diagram of a satellite attitude acquisition system at the exposure moment provided by the present invention.

[0093] The present invention further provides a system 20 for acquiring satellite attitude at exposure time, which is applied to the above-mentioned method for acquiring satellite attitude at exposure time, and comprises:

[0094] Processor 201.

[0095] The memory 202 stores computer-readable instructions. When the computer-readable instructions are executed by the processor 201, the method for acquiring the satellite attitude at the exposure moment of the method embodiment is implemented.

[0096] The exposure moment satellite attitude acquisition system 20 provided in the present invention can execute the above-mentioned exposure moment satellite attitude acquisition method and achieve the same or similar technical effects. To avoid repetition, the present invention will not go into details.

[0097] The beneficial effects brought about by the technical solution provided by the embodiment of the present invention include at least:

[0098] In the present invention, the satellite attitude quaternion representing the satellite attitude synchronized to the GPS is first obtained, and then the accurate attitude quaternion of each exposure image is obtained with a unified timestamp as the interpolation element, and the satellite rotation matrix in the geocentric coordinate system is established based on the satellite attitude quaternion to facilitate the attitude description of the satellite attitude, and then, considering the rotation error of the satellite scanning mirror and the influence of the rotation of the satellite scanning mirror on the line of sight of the infrared payload equipment, the satellite rotation matrix is ​​corrected to obtain an equivalent matrix that can accurately represent the satellite attitude, and then the satellite attitude under each exposure image is accurately obtained, and the influence of satellite data transmission and satellite structure on the satellite attitude at the exposure time is reduced, so as to accurately locate the ground coordinates corresponding to each exposure image and improve the satellite working quality.

[0099] It should be understood that the processor in the embodiment of the present invention may be a central processing unit (CPU), and the processor may also be other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc.

[0100] It should also be understood that the memory in the embodiments of the present invention may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memories. Among them, the non-volatile memory may be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory may be a random access memory (RAM), which is used as an external cache. By way of example and not limitation, many forms of random access memory (RAM) are available, such as static RAM (SRAM), dynamic random access memory (DRAM), synchronous DRAM (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link DRAM (SLDRAM), and direct rambus RAM (DR RAM).

[0101] The above embodiments can be implemented in whole or in part by software, hardware (such as circuits), firmware or any other combination. When implemented by software, the above embodiments can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions or computer programs. When the computer instructions or computer programs are loaded or executed on a computer, the process or function described in the embodiment of the present invention is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from one website, computer, server or data center to another website, computer, server or data center by wired (such as infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device such as a server or data center that contains one or more available media sets. The available medium can be a magnetic medium (for example, a floppy disk, a hard disk, a tape), an optical medium (for example, a DVD), or a semiconductor medium. The semiconductor medium can be a solid-state hard disk.

[0102] It should be understood that the term "and / or" in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship, but it may also indicate an "and / or" relationship. Please refer to the context for specific understanding.

[0103] In the present invention, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c can be represented by: a, b, c, ab, ac, bc, or abc, where a, b, c can be single or multiple.

[0104] It should be understood that in various embodiments of the present invention, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0105] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0106] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described equipment, devices and units can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0107] In the several embodiments provided by the present invention, it should be understood that the disclosed devices, apparatuses and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another device, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0108] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0109] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0110] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention can be essentially or partly embodied in the form of a software product that contributes to the prior art. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in various embodiments of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0111] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

[0112] There are a few points to note:

[0113] (1) The drawings of the embodiments of the present invention only relate to the structures related to the embodiments of the present invention, and other structures may refer to the general design.

[0114] (2) For the sake of clarity, in the drawings used to describe the embodiments of the present invention, the thickness of the layers or regions is exaggerated or reduced, that is, these drawings are not drawn according to the actual scale. It is understood that when an element such as a layer, film, region or substrate is referred to as being "on" or "under" another element, the element may be "directly" "on" or "under" the other element or there may be intermediate elements.

[0115] (3) In the absence of conflict, the embodiments of the present invention and the features therein may be combined with each other to obtain new embodiments.

[0116] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. The protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A method for acquiring satellite attitude at the exposure moment, characterized in that: include: S1: Get satellite attitude quaternion with timestamp; S2: Collect exposure images and exposure image timestamps; S3: performing linear interpolation on the satellite attitude quaternion to obtain the satellite attitude synchronization quaternion of the exposure image at the exposure image timestamp; S4: Calculating the satellite rotation matrix in the geocentric coordinate system according to the satellite attitude synchronization quaternion; S5: Calculating a scanning mirror correction rotation angle including a scanning mirror rotation error of a previous scanning cycle, wherein the scanning mirror is used to collect the exposure image; S6: Calculate the sight vector rotation matrix of the satellite infrared payload equipment under the corrected rotation angle of the scanning mirror; S7: Calculate the equivalent matrix of the satellite attitude by combining the sight vector rotation matrix and the satellite rotation matrix in the geocentric coordinate system to obtain the satellite attitude at the exposure time; Wherein, the S3 specifically includes: S301: Create a first linked list of satellite attitude quaternions and a second linked list of satellite attitude quaternions marked by exposure images, wherein each satellite attitude quaternion in each linked list has a corresponding timestamp; S302: searching the first linked list for two timestamps adjacent to the timestamp of the satellite attitude quaternion marked by the exposure image; S303: performing linear interpolation on the timestamp of the satellite attitude quaternion marked by the exposure image according to the time interval between two adjacent timestamps, to obtain the satellite attitude quaternion corresponding to the timestamp of the satellite attitude quaternion marked by the exposure image; Wherein, the S4 specifically includes: S401: Calculate the satellite rotation matrix in the J2000 inertial coordinate system according to the satellite attitude synchronization quaternion: Wherein, R′ represents the satellite rotation matrix in the J2000 inertial coordinate system, q0, q1, q2, q3 represent the scalar, x-axis component, y-axis component and z-axis component in the satellite attitude synchronization quaternion respectively; S402: performing coordinate system conversion on the satellite rotation matrix in the J2000 inertial coordinate system to obtain the satellite rotation matrix in the geocentric coordinate system; The scanning mirror correction rotation angle is specifically: Δa=ΔA / m i i '=θ i +D a Where m represents the number of exposure images collected in one scanning cycle, θ i represents the rotation angle of the scanning mirror when the i-th exposure image is collected in the previous scanning cycle, ΔA represents the total error of the scanning cycle, Δa represents the rotation angle error of the scanning mirror in each scan, and θ i ' represents the scanning mirror rotation angle when acquiring the i-th exposure image in the current scanning cycle, that is, the scanning mirror correction rotation angle; The sight line vector rotation matrix is ​​specifically: Wherein, R3 represents the sight vector rotation matrix, θ=θ i ' represents the corrected rotation angle of the scanning mirror when acquiring the i-th exposure image in the current scanning cycle; Among them, the equivalent matrix is ​​specifically: Wherein, R represents the equivalent matrix, and R2 represents the installation matrix of the infrared payload in the satellite, i.e., the internal orientation element.

2. The method for acquiring satellite attitude at the exposure time according to claim 1, characterized in that: The satellite attitude quaternion is acquired through a star sensor of the satellite, and the timestamp of the satellite attitude quaternion is synchronized through a GPS positioning system.

3. The method for acquiring satellite attitude at the exposure time according to claim 1, characterized in that: Also includes: S8: Establish an orbital coordinate system with the satellite's center of mass as the origin, and describe the satellite attitude, that is, the satellite attitude at the exposure moment, through the orbital coordinate system.

4. The method for acquiring satellite attitude at the exposure time according to claim 3, characterized in that: The S8 specifically includes: S801: Synchronize satellite speed and satellite position through GPS positioning system; S802: Obtaining a satellite velocity vector and a satellite position vector in a geocentric coordinate system; S803: Combine the satellite velocity vector and the satellite position vector to establish the orbital coordinate system, where the Z axis of the orbital coordinate system points from the origin, i.e., the satellite mass center, to the center of the earth, and the unit vector of each coordinate axis of the orbital coordinate system is: Wherein, x0, y0, z0 represent the X-axis unit vector, Y-axis unit vector and Z-axis unit vector of the orbital coordinate system respectively, r represents the satellite position vector, v represents the satellite velocity vector, and || represents taking the absolute value; S804: Describe the satellite attitude, that is, the satellite attitude at the exposure moment, by using the orbital coordinate system.

5. A satellite attitude acquisition system at the exposure time, characterized in that: include: processor; A memory having computer-readable instructions stored thereon, wherein when the computer-readable instructions are executed by the processor, the method for acquiring the satellite attitude at the exposure moment as described in any one of claims 1 to 4 is implemented.

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