Spacecraft autonomous navigation method and electronic device

Abstract

The application provides a spacecraft autonomous navigation method and electronic equipment. The spacecraft autonomous navigation method comprises the following steps: determining technical indexes of an optical sensor according to navigation requirements, and determining a configuration of the optical sensor according to orbit information of the spacecraft; collecting a star map by using the optical sensor with the determined technical indexes and configuration, processing the star map, identifying a refraction star and extracting a refraction angle; and using a Kalman filtering algorithm to perform information fusion on information output by an inertial navigation system and a refraction apparent height calculated based on the refraction angle, so as to correct navigation errors and obtain corrected navigation information. The application corrects drift errors of the inertial navigation by astronomical navigation, maintains continuous navigation information by using the inertial navigation when the astronomical system is unavailable, and achieves the purpose of improving navigation accuracy.

Description

Technical Field

[0001] This invention belongs to the field of aerospace navigation technology, and in particular relates to a spacecraft autonomous navigation method and electronic equipment. Background Technology

[0002] Currently, the primary navigation method for spacecraft is a combination of inertial navigation (INS) and global positioning satellite navigation (GNSS). In this combined navigation system, GNSS is used to correct errors generated by INS navigation. In ordinary low-speed and non-adversarial application scenarios, this navigation method can achieve sufficient accuracy. However, this combined navigation method relies on the normal and efficient operation of the GNSS system. Under adversarial navigation warfare conditions, the GNSS system may be affected, resulting in reduced accuracy or even severe damage, causing spacecraft using this navigation method to lose their autonomous navigation capabilities. Compared to satellite navigation, celestial navigation offers equivalent navigation accuracy and better autonomy.

[0003] Depending on the sensing method, spacecraft astronomical navigation methods can be divided into two types: direct horizon sensing and indirect horizon sensing using starlight refraction. The basic principle of direct horizon sensing autonomous astronomical navigation is to observe the navigation star using a star sensor and obtain the direction of the starlight in the satellite's coordinate system through coordinate transformation. Then, an Earth sensor or space sextant is used to measure the geocentric direction or horizon direction, thereby calculating the geocentric vector's direction in the satellite's coordinate system. Based on the geometric relationship between the satellite, the observed navigation star, and the Earth, combined with orbital dynamics models and filtering techniques, autonomous navigation of the spacecraft is achieved. This navigation method utilizes existing sensors on the spacecraft (such as star sensors and Earth sensors) as navigation sensors, offering advantages such as low cost, mature technology, and high reliability. However, the accuracy of the geocentric vector directly measured using an Earth sensor is relatively low, limiting the accuracy of this autonomous navigation method.

[0004] The starlight refraction indirect horizon-sensitive method, developed in the early 1980s, is a low-cost, high-precision satellite autonomous navigation method. It utilizes a high-precision star sensor to measure the refraction of starlight as it passes through the Earth's atmosphere, and indirectly obtains horizon information through a mathematical model of the refracted starlight in the atmosphere (atmospheric refraction model), thereby achieving autonomous navigation and positioning for the satellite. Compared to the direct horizon-sensitive method, the biggest advantage of starlight refraction-based autonomous navigation is that it only requires a star sensor to complete autonomous navigation, and its navigation accuracy is not limited by the measurement accuracy of the Earth sensor. However, for starlight refraction navigation to be applied in engineering in my country, several key technologies still need to be solved. For example, the direct measurement information for starlight refraction autonomous navigation is the starlight refraction angle. In practical applications, it is essential to ensure that the star sensor can capture and accurately identify the refracting star, and then obtain the refraction angle. Therefore, the installation of the star sensor and the acquisition of the refraction angle are among the problems that need to be solved.

[0005] Inertial navigation measures the linear acceleration and angular velocity of a vehicle using accelerometers and gyroscopes, and calculates velocity, position, and attitude through integration. Errors accumulate over time (drift), leading to a rapid increase in positioning errors over extended periods. Starlight refraction navigation utilizes the known positions of celestial bodies (such as stars, the sun, and the moon), observing their orientation through photoelectric sensors or star sensors to deduce the vehicle's attitude or position. However, it is significantly affected by weather, cloud cover, and day / night conditions, cannot operate continuously, and produces inconsistent navigation information.

[0006] In summary, during the implementation of this embodiment, the inventors discovered that existing inertial navigation systems suffer from the problem of accumulated errors in output navigation information over time. GNSS systems are susceptible to interference, resulting in low navigation accuracy. While starlight refraction navigation is autonomous, it suffers from poor continuity of output navigation information. Summary of the Invention

[0007] In view of the problems existing in the prior art, the present invention provides a spacecraft autonomous navigation method and electronic equipment, which at least partially solves the problems of low navigation accuracy and poor navigation information continuity caused by interference with error signals in the prior art.

[0008] In a first aspect, embodiments of this disclosure provide a spacecraft autonomous navigation method, including:

[0009] The technical specifications of the optical sensor are determined based on navigation requirements, and the configuration of the optical sensor is determined based on the spacecraft's orbital information.

[0010] Star charts are acquired using optical sensors with defined specifications and configurations. The star charts are then processed to identify refracting stars and extract their refraction angles.

[0011] By using the Kalman filter algorithm, the information output by the inertial navigation system is fused with the refractional apparent height calculated based on the refraction angle to correct navigation errors and obtain corrected navigation information.

[0012] Optionally, the technical specifications include detection band, optical field of view, detection sensitivity, and single-star measurement accuracy; the configuration is a configuration of shared electronics for multiple optical systems.

[0013] Optionally, the optical field of view and detection sensitivity are determined by the following formula to determine the number of stars within the field of view.

[0014] ,

[0015] in, For the apparent magnitude, The field of view is the angle of view.

[0016] Optionally, the configuration of the optical sensor is determined based on the spacecraft's orbital information, including, for a three-axis geostabilized spacecraft, the angle between the optical system's optical axis and the geocentric vector. Calculated using the following formula:

[0017] ,

[0018] in, To refract the apparent height, The orbital altitude of the spacecraft. For the Earth's radius, It is an arcsine function.

[0019] Optionally, the refractive apparent height The angle of refraction is calculated using the following formula:

[0020] ,

[0021] in, It is the angle of refraction.

[0022] Optionally, the process of processing the star map to identify refracting stars and extract refraction angles includes:

[0023] Star map matching is performed on the non-refracting stars in the dark background area of ​​the star map to obtain the attitude information of the optical sensor in the inertial coordinate system;

[0024] Using the attitude information, the star points in the star map are inverted to the celestial coordinate system;

[0025] Using the unmatched star point in the star map as the center in the celestial coordinate system, search for catalog stars within a preset angular distance error range, and calculate the angle between the vector of the line connecting the star point and the catalog star and the geocentric vector. If the angle is less than the preset angular error threshold, the star point is determined to be a refracting star, and the angular distance between the star point and the corresponding catalog star is the refraction angle R, thus completing the identification and extraction of the refraction angle.

[0026] Optionally, the step of performing star map matching on the non-refracting stars in the dark black background area of ​​the star map to obtain the attitude information of the optical sensor in the inertial coordinate system includes:

[0027] The pixel coordinates are projected into unit vectors in the sensor coordinate system using the optical sensor parameters. The unit vector of the reference frame is obtained by looking up the star table. Define the objective function Based on the objective function Obtain the attitude information of the optical sensor in the inertial coordinate system;

[0028] ,

[0029] in, The weight of each star point, For the optical sensor attitude matrix, This represents the total number of data samples.

[0030] Optionally, the step of using the Kalman filter algorithm to fuse the information output by the inertial navigation system with the refractional apparent height calculated based on the refraction angle includes:

[0031] The state prediction period and the measurement update period are defined as follows: the state prediction period is an integer multiple of the measurement update period.

[0032] Optionally, the state prediction period includes constructing a state prediction equation and an error covariance prediction equation.

[0033] The measurement update cycle includes calculating the Kalman gain based on the error covariance prediction equation, updating the state prediction equation based on the Kalman gain, and updating the star map measurements based on the updated state prediction equation.

[0034] Secondly, embodiments of this disclosure also provide an electronic device, the electronic device comprising:

[0035] At least one processor; and,

[0036] A memory communicatively connected to the at least one processor; wherein,

[0037] The memory stores instructions that can be executed by the at least one processor, which, when executed, enable the at least one processor to perform any of the spacecraft autonomous navigation methods described in the first aspect.

[0038] The spacecraft autonomous navigation method provided by this invention identifies the refraction angle from a star chart and uses the refraction apparent altitude calculated from the refraction angle to modify the error of inertial navigation. Since the astronomical information of the star chart is not easily disturbed, astronomical navigation is used to correct the drift error of inertial navigation. Inertial navigation is used to maintain the continuity of navigation information when the astronomical system is unavailable, thereby achieving the purpose of improving navigation accuracy and continuity. Attached Figure Description

[0039] The above and other objects, features and advantages of this disclosure will become more apparent from the accompanying drawings, in which like reference numerals generally denote like parts.

[0040] Figure 1 This is a schematic diagram of the starlight refraction navigation principle provided in an embodiment of the present disclosure;

[0041] Figure 2A schematic diagram of the optical sensor composition provided in the embodiments of this disclosure;

[0042] Figure 3 A schematic diagram of the optical sensor's position on a spacecraft, provided in an embodiment of this disclosure;

[0043] Figure 4 A typical star map diagram provided for embodiments of this disclosure;

[0044] Figure 5 This is a schematic diagram of an inversion star map provided in an embodiment of this disclosure;

[0045] Figure 6 A block diagram of inertial / astronomical integrated navigation provided for embodiments of this disclosure;

[0046] Figure 7 A flowchart of the Kalman filter algorithm provided in this embodiment of the disclosure;

[0047] Figure 8 This is a schematic block diagram of an electronic device provided in an embodiment of the present disclosure. Detailed Implementation

[0048] The embodiments of this disclosure will now be described in detail with reference to the accompanying drawings.

[0049] It should be understood that the following specific examples illustrate the implementation of this disclosure, and those skilled in the art can easily understand other advantages and effects of this disclosure from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. This disclosure can also be implemented or applied through other different specific implementation methods, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this disclosure. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0050] It should be noted that various aspects of the embodiments described below are within the scope of the appended claims. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this disclosure, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using other structures and / or functionalities besides one or more of the aspects set forth herein.

[0051] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this disclosure. The illustrations only show the components related to this disclosure and are not drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0052] Furthermore, specific details are provided in the following description to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that the described aspects can be practiced without these specific details.

[0053] Refractional apparent altitude refers to the virtual altitude corresponding to the center point of the Earth's atmospheric refraction zone, which is selected as the main observation target in starlight refraction navigation.

[0054] The principle of the spacecraft autonomous navigation method implemented in this paper is as follows: Figure 1 As shown, the method specifically includes:

[0055] The technical specifications of the optical sensor are determined based on navigation requirements, and the configuration of the optical sensor is determined based on the spacecraft's orbital information.

[0056] The selection of optical sensor technical specifications mainly includes optical field of view, detection band, detection sensitivity, and single-satellite measurement accuracy.

[0057] Detection bands:

[0058] The detection wavelength of the optical sensor directly determines the distribution of observable stars on the celestial sphere. Based on the technological maturity of the detector, the visible light band with a wavelength range of 380nm to 750nm (center wavelength 550nm) was selected, and a CMOS array imaging detector was chosen, which has advantages such as low noise, high dynamic range, and good imaging quality. After the detection wavelength was selected, the star image processing algorithm used the visible magnitude (V) of stars to create a star catalog.

[0059] Optical field of view and detection sensitivity:

[0060] The number of stars in the field of view can be calculated using the formula below.

[0061] ,

[0062] in, For the apparent magnitude, The field of view is the angle of view.

[0063] Unlike ordinary star sensors for deep-sky imaging, the refractor needs to image the edge of Earth. Approximately one-third to one-half of the field of view is the Earth background. If the field of view is too large, the larger the Earth background area enters, the greater the background noise, which is detrimental to star image processing. If the field of view is too small, the number of observable stars is limited. Therefore, a magnitude 7 star was selected, with a field of view angle of 8° × 8°. Calculations show approximately 19 stars within the field of view. Even with the Earth background occupying half, there are still 10 stars available for attitude determination.

[0064] Single-satellite measurement accuracy:

[0065] The measurement angle of a single star directly determines the accuracy of the refraction angle extraction, thus affecting navigation accuracy. Based on the starlight atmospheric refraction model and empirical formulas, the apparent altitude of refraction can be expressed as:

[0066] ,

[0067] In the formula, R is the angle of refraction.

[0068] By selecting an observation refraction zone at an altitude of 20km-35km above the Earth's surface, it can be determined that the refraction angle ranges from [30, 320] arcseconds. Therefore, the single-star measurement accuracy of the optical sensor should be better than 2 arcseconds to effectively extract the refraction angle.

[0069] The optical sensor employs a dual optical system plus electronic components, such as... Figure 2 As shown. The sensor's body coordinate system is OsXsYsZs, and the angle between the optical axes of the optical system is 2. , The angle is related to the spacecraft's orbit. Assuming the spacecraft's orbital altitude is h, and the spacecraft's long-term on-orbit attitude is three-axis Earth-stable with an orbital attitude angle of 0, the angle can be calculated using the following formula. :

[0070] ,

[0071] In the formula, To refract the apparent height, Take 30km;

[0072] Optical sensors are installed at spacecraft locations, such as... Figure 3 As shown, the optical axes of the two optical systems lie in the YbObZb plane of the spacecraft's body coordinate system, with Zs coinciding with Zb.

[0073] Two optical systems acquire images separately, which are then processed in the electronics section, which shares components such as the processor and memory. The refracting stars, non-refracting stars, and the Earth background are captured in the same star image, avoiding the refraction angle extraction errors caused by attitude changes between the two sensors when using different sensors to acquire refracting and non-refracting stars separately.

[0074] For example, star charts can be acquired using optical sensors with defined specifications and configurations, the star charts can be processed, refracting stars can be identified, and the refraction angles can be extracted.

[0075] Typical star charts acquired by optical sensors, such as Figure 4 As shown, the image is divided into a deep black background area, an atmospheric glow band, a refraction band, and an Earth background. Non-refracting stars are located in the deep black background area, while refracting stars are located in the refraction band.

[0076] Star pose on a dark background:

[0077] First, extract the coordinates of star points in the deep black and cool scene area. Assuming that the star map matching algorithm is used to obtain the centroid positions of star points in the phase plane [Xi,Yi], i=1...N, where N is the number of star points.

[0078] The pixel coordinates are projected into a unit vector in the sensor coordinate system using optical sensor parameters (focal length, principal point, radial distortion, etc.). The unit vector of the reference frame (J2000 equatorial inertial frame) is obtained by looking up the star table. Define the objective function:

[0079] ,

[0080] In the formula, The weight of each star point.

[0081] Then find the matrix corresponding to minimizing the objective function. This is the attitude matrix of the optical sensor.

[0082] Define matrix :

[0083] ,

[0084] Define rotation matrix With quaternions The correspondence can be expressed as follows:

[0085] ,

[0086] in,

[0087] ,

[0088] In the formula,

[0089] , , ,

[0090] The optimal quaternion is The eigenvector corresponding to the largest eigenvalue.

[0091] The above calculations yield the attitude quaternion of the optical sensor in the J2000 coordinate system.

[0092] Star chart inversion:

[0093] Using the obtained attitude, the refracting and non-refracting stars in the phase plane are inverted to the celestial coordinate system, such as... Figure 5 As shown.

[0094] It is known that stars in the refraction zone will not be able to coincide with stars in the star catalog. The angular distance difference between the two is the size of the refraction angle. At the same time, stars that fail to match and stars that are mistakenly extracted will also be inverted to the celestial coordinate system.

[0095] Refracting star identification and refraction angle extraction:

[0096] Define the sequence of unmatched stars as Mi = [Xi, Yi], i = 1...M;

[0097] Define the magnitude of angular distance error With Mi as the center, Draw a circle with radius [Xi, Yi]. If there are catalog stars within this circle, record them and proceed to the next step, obtaining a star point sequence Ni=[Xi, Yi], i=1...N that meets the conditions. Simultaneously, record the corresponding catalog star Si=[Xi, Yi]. , ], i=1...N, where Right ascension, It is the declination.

[0098] Define angle error Calculate the angle between the NiSi vector and the geocentric vector. A star that meets the following conditions is a refracted star:

[0099] ,

[0100] Select the refracting stars that meet the conditions and calculate the angle of refraction corresponding to the refracting star, denoted as R.

[0101] By using the Kalman filter algorithm, the information output by the inertial navigation system is fused with the refractional apparent height calculated based on the refraction angle to correct navigation errors and obtain corrected navigation information.

[0102] In addition to the optical observer, the hardware device in this embodiment should also include an inertial measurement unit (including a gyroscope and an accelerometer) and a comprehensive processing computer. The inertial measurement unit provides attitude recursion and apparent acceleration calculation, and the inertial / astronomical integrated navigation algorithm is implemented in the comprehensive processing computer. Figure 6 As shown.

[0103] To ensure real-time performance and reduce the amount of data transmitted through the interface, the star map processing section is implemented in the optical sensor electronics section. By extracting star points and matching star maps with non-refracting stars, accurate attitude information can be obtained. The attitude information is output to attitude dynamics to correct the attitude information calculated by the gyroscope and output the spacecraft attitude information. The attitude information obtained from non-refracting star processing is fed into the refracting star extraction algorithm to obtain the refraction angle. The apparent altitude is calculated through the apparent altitude module and fed into orbit dynamics to correct the inertial navigation information and output the spacecraft position and velocity information.

[0104] The two optical systems form different star charts, resulting in different geometrical distributions of apparent altitude, which helps to improve the accuracy and speed of position and velocity convergence.

[0105] Measurement value calculation:

[0106] Using the refracted apparent altitude as the measurement value, the refracted apparent altitude is obtained based on the starlight atmospheric refraction model and empirical formulas. .

[0107] Information fusion algorithm for measurement information that is out of time:

[0108] Based on the asynchronous exposure times of two star charts, which leads to asynchronous timestamps in measurement information, a Kalman filter algorithm is proposed for information fusion. The Kalman filter algorithm consists of the following two steps: The state prediction period is set to dt1, and the measurement update period is set to dt2, where dt2 / dt1 = H, and H is an integer multiple, typically H = 100. The star chart... Figure 1 The arrival time of the visual altitude information obtained from the processing result is denoted as Flag1=1, star Figure 2 The arrival time of the visual height information obtained from the processing result is denoted as Flag2=1.

[0109] Step 1: State Prediction

[0110] State prediction in one step:

[0111] ,

[0112] One-step prediction of covariance matrix:

[0113] ,

[0114] Step 2: Measurement Update

[0115] star Figure 1 Message arrival processing, Flag1=1:

[0116] Calculate the Kalman gain:

[0117] ,

[0118] Update the covariance matrix:

[0119] ,

[0120] Measurement value 1 updated:

[0121] ,

[0122] star Figure 2 Message arrival processed, Flag2=1:

[0123] Calculate the Kalman gain:

[0124] ,

[0125] Update the covariance matrix:

[0126] ,

[0127] Measurement value 2 updated:

[0128] ,

[0129] The Kalman filter algorithm program flow is as follows: Figure 7 As shown.

[0130] The electronic device disclosed in this embodiment includes a memory and a processor. The memory is used to store non-transitory computer-readable instructions. Specifically, the memory may include one or more computer program products, which may include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. The volatile memory may, for example, include random access memory (RAM) and / or cache memory. The non-volatile memory may, for example, include read-only memory (ROM), hard disk, flash memory, etc.

[0131] The processor may be a central processing unit (CPU) or other processing unit with data processing and / or instruction execution capabilities, and may control other components in the electronic device to perform desired functions. In one embodiment of this disclosure, the processor is used to execute computer-readable instructions stored in the memory, causing the electronic device to perform all or part of the steps of the spacecraft autonomous navigation methods described in the foregoing embodiments of this disclosure.

[0132] Those skilled in the art will understand that, in order to solve the technical problem of how to achieve a good user experience, this embodiment may also include well-known structures such as communication buses and interfaces, and these well-known structures should also be included within the protection scope of this disclosure.

[0133] like Figure 8This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present disclosure. It illustrates a structural schematic diagram suitable for implementing the electronic device in the embodiment of the present disclosure. Figure 8 The electronic device shown is merely an example and should not be construed as limiting the functionality and scope of the embodiments disclosed herein.

[0134] like Figure 8 As shown, an electronic device may include a processing unit (such as a central processing unit, graphics processing unit, etc.) that can perform various appropriate actions and processes based on a program stored in read-only memory (ROM) or a program loaded from a storage device into random access memory (RAM). The RAM also stores various programs and data required for the operation of the electronic device. The processing unit, ROM, and RAM are interconnected via a bus. Input / output (I / O) interfaces are also connected to the bus.

[0135] Typically, the following devices can be connected to the I / O interface: input devices, such as sensors or visual information acquisition devices; output devices, such as displays; storage devices, such as magnetic tapes or hard drives; and communication devices. Communication devices allow electronic devices to exchange data wirelessly or via wired communication with other devices, such as edge computing devices. Although Figure 8 Electronic devices with various devices are shown, but it should be understood that it is not required to implement or have all of the devices shown. More or fewer devices may be implemented or have instead.

[0136] In particular, according to embodiments of this disclosure, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments of this disclosure include a computer program product comprising a computer program carried on a non-transitory computer-readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via a communication device, or installed from a storage device, or installed from a ROM. When the computer program is executed by a processing device, all or part of the steps of the spacecraft autonomous navigation method of embodiments of this disclosure are performed.

[0137] For a detailed description of this embodiment, please refer to the corresponding descriptions in the foregoing embodiments, which will not be repeated here.

[0138] A computer-readable storage medium according to embodiments of the present disclosure stores non-transitory computer-readable instructions. When these non-transitory computer-readable instructions are executed by a processor, all or part of the steps of the spacecraft autonomous navigation methods described in the foregoing embodiments of the present disclosure are performed.

[0139] The aforementioned computer-readable storage media include, but are not limited to: optical storage media (e.g., CD-ROM and DVD), magneto-optical storage media (e.g., MO), magnetic storage media (e.g., magnetic tape or portable hard drive), media with built-in rewritable non-volatile memory (e.g., memory card), and media with built-in ROM (e.g., ROM cartridge).

[0140] For a detailed description of this embodiment, please refer to the corresponding descriptions in the foregoing embodiments, which will not be repeated here.

[0141] The basic principles of this disclosure have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this disclosure are merely examples and not limitations, and should not be considered as essential features of each embodiment of this disclosure. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the scope of this disclosure to the necessity of employing the aforementioned specific details for implementation.

[0142] In this disclosure, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. The block diagrams of devices, apparatuses, devices, and systems involved in this disclosure are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, apparatuses, devices, and systems can be connected, arranged, and configured in any manner. Words such as "comprising," "including," "having," etc., are open-ended terms meaning "including but not limited to," and are used interchangeably with them. The terms "or" and "and" as used herein refer to the terms "and / or," and are used interchangeably with them unless the context clearly indicates otherwise. The term "such as" as used herein refers to the phrase "such as but not limited to," and is used interchangeably with it.

[0143] Additionally, as used herein, the "or" used in a list of items beginning with "at least one" indicates a separate list, such that a list of, for example, "at least one of A, B, or C" means A or B or C, or AB or AC or BC, or ABC (i.e., A and B and C). Furthermore, the word "exemplary" does not imply that the described example is preferred or better than other examples.

[0144] It should also be noted that in the systems and methods of this disclosure, the components or steps can be decomposed and / or recombined. These decompositions and / or recombinations should be considered as equivalent solutions to this disclosure.

[0145] Various changes, substitutions, and modifications can be made to the technology described herein without departing from the teachings defined by the appended claims. Furthermore, the scope of the claims of this disclosure is not limited to the specific aspects of the processes, machines, manufactures, events, means, methods, and actions described above. Currently existing or later-developed processes, machines, manufactures, events, means, methods, or actions that perform substantially the same function or achieve substantially the same result as the corresponding aspects described herein can be utilized. Therefore, the appended claims include such processes, machines, manufactures, events, means, methods, or actions within their scope.

[0146] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use this disclosure. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects without departing from the scope of this disclosure. Therefore, this disclosure is not intended to be limited to the aspects shown herein, but rather to be carried out within the widest scope consistent with the principles and novel features disclosed herein.

[0147] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of this disclosure to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations therein.

Claims

1. A spacecraft autonomous navigation method, characterized in that, The method comprises the following steps: determining technical indexes of the optical sensor according to navigation requirements, and determining a configuration of the optical sensor according to orbit information of the spacecraft; collecting a star map by using the optical sensor with the determined technical indexes and configuration, processing the star map, identifying refraction stars and extracting refraction angles; performing information fusion on information output by an inertial navigation system and refraction apparent heights calculated based on the refraction angles by using a Kalman filtering algorithm, to correct navigation errors and obtain corrected navigation information; the technical indexes include a detection waveband, an optical field of view, detection sensitivity and single-star measurement accuracy; the optical field of view and the detection sensitivity are determined by the following formula to determine the number of stars in the field of view, ， wherein is apparent magnitude, is apparent field angle; The optical sensor adopts a double optical system, and the included angle between the optical axes of the optical system is 2 ; The configuration of the optical sensor is determined according to the orbit information of the spacecraft, and the configuration of the optical sensor includes: for a three-axis stabilized spacecraft, the angle between the optical axis of the optical system and the earth's vector is calculated by the following formula : ， wherein, is the refracted visual height, is the spacecraft operating orbital height, is the Earth radius, is the inverse sine function.

2. The spacecraft autonomous navigation method according to claim 1, characterized in that, the configuration is a configuration of multiple optical systems sharing an electronic part.

3. The spacecraft autonomous navigation method of claim 1, wherein, the refracted visual height The angle of refraction is calculated from the angle of incidence by the following equation: ， wherein is the angle of refraction.

4. The spacecraft autonomous navigation method of claim 1, wherein, the processing of the star map, the identification of the refraction stars and the extraction of the refraction angles comprise: performing star map matching on non-refraction stars in a deep black background area of the star map, to obtain attitude information of the optical sensor in an inertial coordinate system; inverting star points in the star map to a celestial coordinate system by using the attitude information; searching for a star table star within a preset angular distance error range with the star point in the celestial coordinate system as a center, and calculating an included angle between a connecting vector of the star point and the star table star and an earth center vector, if the included angle is less than a preset angle error threshold, the star point is determined as a refraction star, and an angular distance between the star point and the corresponding star table star is the refraction angle R, thereby completing the identification and extraction of the refraction angle.

5. The spacecraft autonomous navigation method of claim 1, wherein, the star map matching on the non-refraction stars in the deep black background area of the star map, to obtain the attitude information of the optical sensor in the inertial coordinate system, comprises: Projecting the pixel coordinates into a unit vector in the sensor coordinate system using the optical sensor parameters , obtaining the unit vector of the reference frame from the star table , defining the objective function , obtaining the attitude information of the optical sensor in the inertial coordinate system based on the objective function ​ ， wherein, is the weight for each star point, is the optical sensor attitude matrix, is the total number of data samples.

6. The spacecraft autonomous navigation method of claim 1, wherein, the information fusion on the information output by the inertial navigation system and the refraction apparent heights calculated based on the refraction angles by using the Kalman filtering algorithm comprises: a state prediction period and a measurement update period, the state prediction period is an integer multiple of the measurement update period.

7. The spacecraft autonomous navigation method of claim 6, wherein, the state prediction period comprises constructing a state prediction equation and an error covariance prediction equation, the measurement update period comprises calculating a Kalman gain based on the error covariance prediction equation, updating the state prediction equation based on the Kalman gain, and updating a measurement value of the star map based on the updated state prediction equation.

8. An electronic device, comprising: The electronic device comprises: at least one processor; and a memory connected to the at least one processor in communication; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform the spacecraft autonomous navigation method according to any one of claims 1-7.

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