A method and device for processing dynamic star images of star sensors based on gyroscope assistance

Abstract

The present invention discloses a method and device for processing a dynamic star image of a star sensor based on gyro assistance. The method first establishes a star sensor motion rate estimation model based on gyro information and its estimation error, then uses correlation to express the relationship between motion rate and star imaging and establishes an observation model of star spots; based on the characteristics of multiple star spots in the image, a joint observation of star spots in the image is established; according to the established star sensor motion rate value range, a motion rate combination sequence is constructed, and the optimal motion rate is found by traversing the star spot joint observation corresponding to all motion rate combinations, and the detection of star spots is realized. The present invention realizes the detection of dynamic star spots of star sensors assisted by gyro, improves the detection rate of dim star spots, improves the accuracy and reliability of the output attitude of the star sensor under dynamic conditions, and finally improves the dynamic performance of the star sensor.

Description

Technical Field

[0001] The present invention relates to the technical field of star sensors, and in particular to a gyro-assisted star sensor dynamic star map processing method and device. Background Art

[0002] Star sensors detect stars on the celestial sphere and calculate their attitudes, which is an important step in understanding stars. In order to ensure that the calculated attitude is accurate and reliable, at least 4 stars need to be detected in the collected star images. In dynamic conditions, the star spots imaged by the star sensor will appear blurred and trailing, resulting in a decrease in the signal-to-noise ratio of the imaging spot, making the star spots difficult to detect. At present, there are some methods that detect such star spots through image enhancement methods. Such methods usually need to traverse the entire motion information value range, with high computational complexity and large amount of calculation. In addition, these directions have a certain range of use and do not conform to the situation where the motion state of the star sensor changes when it is in orbit.

[0003] Based on the above characteristics, the rate information provided by the gyroscope can be used to realize the prior information of the motion information of the star sensor, and realize the processing of dynamic star maps and the detection of star spots. However, the measurement accuracy of the gyroscope is limited, and the motion information provided will have certain errors; in addition, the motion of the star sensor on orbit is not an ideal uniform motion, but usually a variable speed motion with a certain acceleration. The detection effect may be limited if it is completely based on the gyroscope information.

[0004] Therefore, the present invention proposes a method for detecting imaging spots of a star sensor using a gyro to assist the star sensor, so as to solve the above-mentioned problems. Summary of the invention

[0005] The purpose of the present invention is to provide a gyro-assisted star sensor dynamic star map processing method and device to address the deficiencies of the prior art. The present invention can detect dim star spots in dynamic conditions when the star sensor has complex motion changes, thereby improving the reliability of the star sensor's normal operation in dynamic conditions.

[0006] The objective of the present invention is achieved through the following technical solutions: A first aspect of an embodiment of the present invention provides a gyro-assisted star sensor dynamic star map processing method, comprising the following steps:

[0007] (1) Estimate the motion information of the star sensor in the current frame based on the gyro information, obtain the estimated error of the star sensor motion information based on the gyro measurement error, and establish the motion information value range of the star sensor estimated based on the gyro information according to the motion information of the star sensor in the current frame and the estimated error of the star sensor motion information;

[0008] (2) Establishing a combined sequence of the three-axis motion information of the star sensor based on the motion information value range of the star sensor;

[0009] (3) selecting a set of motion information combinations from the combined sequence of motion information constructed in step (2), and constructing predicted images of star spot imaging at different positions within the field of view of the star sensor based on the selected motion information;

[0010] (4) constructing the observation probability of the star spot based on the predicted image of the star spot imaging constructed in step (3);

[0011] (5) Based on the observation probability of the star spots constructed in step (4), the joint observation probability of all star spots in the image is established using the joint probability method;

[0012] (6) Select another set of motion information combinations from the motion information combination sequence constructed in step (2), and repeat steps (3) to (5) until all motion information combinations are traversed to obtain the joint observation probability of the corresponding star spot under each motion information combination;

[0013] (7) Resetting the step range according to the predicted direction of motion of the star spot to reduce the number of motion information combinations in step (6);

[0014] (8) Based on the remaining motion information combination after the trimming in step (7), the optimal motion information is determined according to the joint observation probability of the corresponding star spots to detect the star spots.

[0015] Furthermore, in step (1), estimating the motion information of the star sensor in the current frame according to the gyroscope information specifically includes:

[0016] The gyro information is the three-axis motion information measured by the gyro, expressed as ,in , and They represent the movement rates of the x-axis, y-axis, and z-axis measured by the gyroscope, respectively, and the superscript T represents the transpose of the matrix;

[0017] The three-axis motion information of the star sensor in the current frame is estimated based on the three-axis motion information measured by the gyroscope, which is expressed as:

[0018]

[0019] in, Represents the three-axis motion information of the star sensor, , , They represent the movement rates of the star sensor along the x-axis, y-axis, and z-axis respectively.

[0020] Furthermore, in step (1), the estimated error of the star sensor motion information is obtained based on the measurement error of the gyroscope, and is obtained by the following formula:

[0021]

[0022]

[0023]

[0024] in, The estimated error matrix representing the star sensor motion information; represents the measurement error matrix of the gyroscope, , and Respectively represent the measurement errors of the gyroscope on the x-axis, y-axis and z-axis; The Jacobian matrix representing the error in the estimation of the star sensor motion information.

[0025] Furthermore, in step (2), establishing a combination sequence of three-axis motion information of the star sensor according to the motion information value range of the star sensor specifically includes:

[0026] In the motion information value range of the star sensor, the step range is set to determine the combination sequence of the three-axis motion information of the star sensor, which is expressed as:

[0027]

[0028] in, The combination of the three-axis motion information of the star sensor Axis speed combination Rate, Axis speed combination Rate and Axis speed combination rate, , and The speed combinations around the x-axis, y-axis and z-axis in the combination of the three-axis motion information of the star sensor are respectively , and rate.

[0029] Furthermore, in step (3), the predicted image of the star spot imaging is represented by a matrix M, where M is a matrix containing The element values ​​in the matrix M are described by the following formula:

[0030]

[0031] in, is a set of elements with value 1 passing through the center of the matrix, for Middle The element values ​​of the elements represent star spots. The angle between the straight line they constitute and the horizontal direction defines the direction of the predicted image of the star spot imaging, that is, the direction of the star spot movement; the number of these elements defines the length of the star spot, and the length of a single side of the matrix M is taken as m.

[0032] Furthermore, in step (4), constructing the observation probability of the star spot based on the predicted image of the star spot imaging constructed in step (3) specifically includes:

[0033] First, the correlation between the predicted image of star spot imaging and the collected original image is calculated, which is expressed as:

[0034]

[0035] in, represents the original image collected, M represents the predicted image of star spot imaging, and G represents the correlation calculation result;

[0036] Then, the observation probability of the i-th star spot pixel is constructed according to the Gaussian probability model, which is expressed as:

[0037]

[0038] in, is the observation probability of the i-th star spot pixel, and are the mean and standard deviation of the Gaussian probability model of the i-th star spot, Represents the gray value of the i-th star spot pixel after correlation calculation.

[0039] Furthermore, in step (5), the joint observation probability of all star spots in the image is expressed as:

[0040]

[0041] in, represents the joint observation probability of all star spots in the current frame image, Indicates The probability of observing a star spot.

[0042] Furthermore, in step (8), the optimal motion information is obtained by the following method:

[0043] The maximum joint observation probability is found among the joint observation probabilities of the star spots corresponding to the remaining motion information combinations after the pruning in step (7), and the optimal motion information of the star sensor is determined according to the motion information combination corresponding to the maximum joint observation probability.

[0044] A second aspect of an embodiment of the present invention provides a gyro-assisted star sensor dynamic star map processing device, comprising one or more processors and a memory, wherein the memory is coupled to the processor; wherein the memory is used to store program data, and the processor is used to execute the program data to implement the above-mentioned gyro-assisted star sensor dynamic star map processing method.

[0045] A third aspect of an embodiment of the present invention provides a computer-readable storage medium having a program stored thereon, which, when executed by a processor, is used to implement the above-mentioned gyro-assisted star sensor dynamic star map processing method.

[0046] The beneficial effects of the present invention are as follows: the present invention solves the problem of gyro measurement error by establishing a value range of motion information of a star sensor, and further traversing the value range to estimate the optimal motion information; based on the low signal-to-noise ratio of star imaging spots in a dynamic star map, the present invention establishes a correlation between predicted star spots and real imaging images, constructs the observation probability of star spots by using the correlation, and estimates the optimal motion information and detects the spots by joint observation of all star spots in the image, so that star spots with a low signal-to-noise ratio can be detected, and the star sensor can output an accurate and reliable attitude in a dynamic situation; the present invention realizes the detection of dynamic star spots of a star sensor assisted by a gyro, improves the detection rate of faint star spots, improves the accuracy and reliability of the output attitude of the star sensor in a dynamic situation, and finally improves the dynamic performance of the star sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is a flow chart of a method for processing a dynamic star map of a star sensor based on gyro assistance in an embodiment of the present invention;

[0048] Figure 2 A schematic diagram of an installation relationship between a gyroscope and a star sensor in an embodiment of the present invention;

[0049] Figure 3 is an example diagram of a typical predicted spot image in an embodiment of the present invention;

[0050] Figure 4 This is an example diagram of dividing a star image into 9 areas in an embodiment of the present invention;

[0051] Figure 5 This is an example diagram of predicting the division of the motion direction of a star spot in an embodiment of the present invention;

[0052] Figure 6 This is a star image with a rate of 10° / s and an exposure time of 100ms and its extraction result in an embodiment of the present invention; wherein, Figure 6 (a) is a star image with an exposure rate of 10° / s and an exposure time of 100ms (displayed in 5 times grayscale); Figure 6 (b) in the figure is the extraction result of the star image;

[0053] Figure 7 The present invention is a schematic diagram of a gyro-assisted dynamic star map processing device for a star sensor according to an embodiment of the present invention. DETAILED DESCRIPTION

[0054] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Instead, they are merely examples of devices and methods consistent with some aspects of the present invention as detailed in the appended claims.

[0055] The terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The singular forms "a", "the" and "the" used in the present invention and the appended claims are also intended to include plural forms unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0056] It should be understood that although the terms first, second, third, etc. may be used in the present invention to describe various information, these information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present invention, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining".

[0057] The present invention is described in detail below in conjunction with the accompanying drawings. In the absence of conflict, the features of the following embodiments and implementations can be combined with each other.

[0058] See also Figure 1 The gyro-assisted star sensor dynamic star map processing method of the present invention specifically comprises the following steps:

[0059] (1) Estimate the motion information of the star sensor in the current frame based on the gyro information, obtain the estimated error of the star sensor motion information based on the gyro measurement error, and establish the motion information value range of the star sensor based on the gyro information estimation according to the motion information of the star sensor in the current frame and the estimated error of the star sensor motion information.

[0060] Furthermore, there is a fixed connection between the coordinate systems of the star sensor and the gyroscope, which can be expressed as:

[0061]

[0062] in, and denote the vectors of star sensor and gyro measurement respectively, represents the rotation matrix, which can be obtained by joint calibration of the star sensor and the gyro. An installation relationship between the gyro and the star sensor is as follows: Figure 2 As shown, the definition of the coordinate axes in the gyroscope's coordinate system and the star sensor's coordinate system is shown.

[0063] Furthermore, the motion information of the star sensor in the current frame is estimated based on the gyro information, specifically including: the gyro information is the three-axis motion information measured by the gyro, expressed as ,in, , and They represent the movement rates of the x-axis, y-axis, and z-axis measured by the gyroscope, respectively. The superscript T represents the transpose of the matrix. The three-axis motion information of the star sensor in the current frame is estimated based on the three-axis motion information measured by the gyroscope, which is expressed as:

[0064]

[0065] in, Represents the three-axis motion information of the star sensor, , , They represent the movement rates of the star sensor along the x-axis, y-axis, and z-axis respectively.

[0066] Furthermore, the estimated error of the star sensor motion information is obtained according to the measurement error of the gyroscope, which is obtained by the following formula:

[0067]

[0068]

[0069]

[0070] in, The estimated error matrix representing the star sensor motion information; represents the measurement error matrix of the gyroscope, The value of is obtained when the gyro leaves the factory. , and Respectively represent the measurement errors of the gyroscope on the x-axis, y-axis and z-axis; The Jacobian matrix representing the error in the estimation of the star sensor motion information.

[0071] Furthermore, the expression of the motion information range of the star sensor is:

[0072]

[0073] in, , and Represents the estimated error of the star sensor motion rate estimated on the x-axis, y-axis and z-axis respectively, and is the estimated error matrix of the star sensor motion information The elements in .

[0074] (2) Establish a combined sequence of the three-axis motion information of the star sensor based on the motion information value range of the star sensor.

[0075] Furthermore, a combination sequence of the three-axis motion information of the star sensor is established according to the motion information value range of the star sensor, specifically including: setting a step range in the motion information value range of the star sensor, and determining all possible combinations of the three-axis motion information of the star sensor, that is, the combination sequence of the three-axis motion information of the star sensor, which is expressed as:

[0076]

[0077] in, The combination of the three-axis motion information of the star sensor Axis speed combination Rate, Axis speed combination Rate and Axis speed combination rate, , and The speed combinations around the x-axis, y-axis and z-axis in the combination of the three-axis motion information of the star sensor are respectively , and rate.

[0078] (3) Selecting a set of motion information combinations from the combined sequence of motion information constructed in step (2), and constructing predicted images of star spot imaging at different positions within the field of view of the star sensor based on the selected motion information.

[0079] Furthermore, the predicted image of star spot imaging is represented by a matrix M, where M is a matrix containing The element values ​​in the matrix M are described by the following formula:

[0080]

[0081] in, is a set of elements with value 1 passing through the center of the matrix, for Middle The element values ​​of the elements represent star spots. The angle between the straight line and the horizontal direction defines the direction of the predicted image of star spot imaging, that is, the direction of star spot movement; the number of these elements defines the length of the star spot, and the length of one side of the matrix M is m. A typical example of a predicted image of star spot imaging is as follows Figure 3 shown.

[0082] It should be noted that when constructing predicted images of star spot imaging at different positions in the field of view of the star sensor based on the selected motion information, due to different combinations of motion information, the starting positions of the star spots are different within the same exposure time. Therefore, the motion directions of the star spots corresponding to different combinations of motion information are different, and their lengths may also be different.

[0083] It should be noted that after the star sensor is manufactured, the optical focal length, the coordinate system of the imaging image, and the pixel spacing of the imaging chip are already determined. The movement direction of the star spot is only related to the position of the star point, the movement speed of the star sensor, and the exposure time. When the axis rotates, the movement direction of the light spots at different positions in the image will be inconsistent. At the same time, considering the actual orbiting star sensor The rate is limited, so the star image is divided into 9 regions, such as Figure 4 As shown, the movement direction of the light spot is estimated in each area respectively, and it is assumed that the movement directions of the star light spots at different positions in the same area are the same, while the movement directions of the star light spots in different areas may be different.

[0084] by Figure 4 Taking region ① in the figure as an example, the following describes the process of determining the direction of motion of the star spot. Other regions can be obtained by similar methods.

[0085] First, a pixel at the center of area ① is randomly selected as the star incident optical position at the start of the star sensor exposure, that is, the starting position of the star spot, recorded as , then the incident starlight vector is expressed as:

[0086]

[0087] in, is the incident starlight vector, and is the origin coordinate of the star sensor coordinate system, is the focal length.

[0088] Then, a set of motion information combinations is selected from the combined sequence of motion information constructed in step (2), and the current motion rate value is taken as , the exposure time is , then the position of the incident light of the star at the end of exposure, that is, the position of the tail of the star spot tail, is calculated by the following formula:

[0089]

[0090]

[0091]

[0092] in, , and They represent the rotation angles of the star sensor in the x-axis, y-axis, and z-axis directions at the current time. The starlight vector representing the star spot at the beginning of exposure, The starlight vector representing the star spot at the end of exposure, Representation Matrix The third item, Indicates the position of the star spot in the star sensor imaging image at the end of exposure.

[0093] Secondly, according to the starting position and tail position of the star spot, the predicted movement direction and length of the star spot are determined by the following formula:

[0094]

[0095]

[0096] in, is the predicted direction of star spot movement, is the predicted star spot tail length.

[0097] Finally, according to the predicted length of the star's tail Determine the size m of the matrix M:

[0098]

[0099] in, is the star spot tail length threshold. In this embodiment, , obtained from the experiment statistics.

[0100] (4) Based on the predicted image of the star spot imaging constructed in step (3), the observation probability of the star spot is constructed.

[0101] Furthermore, based on the predicted image of the star spot imaging constructed in step (3), the observation probability of the star spot is constructed, which specifically includes:

[0102] (4.1) First, the correlation between the predicted image of star spot imaging and the collected original image is calculated, which is expressed as:

[0103]

[0104] in, represents the original image collected, M represents the predicted image of star spot imaging, and G represents the correlation calculation result.

[0105] Specifically, the collected original star spot imaging image is evenly divided into 9 area blocks, and the predicted image of the star spot imaging is determined according to step (3), which is expressed as:

[0106]

[0107]

[0108] in, and Represent the pixel coordinate sets of the entire image and the sub-block respectively, Indicates The predicted image of the star spot imaging is then correlated with each image block and the corresponding predicted image, expressed as:

[0109]

[0110] in, and Respectively represent The original and correlation calculated grayscale values ​​of the star spot pixels.

[0111] It should be understood that only after the observation probability of the star spot on each pixel is established can the observation of the star spot on the entire image be gradually constructed.

[0112] (4.2) Then, the observation probability of the i-th star spot pixel is constructed according to the Gaussian probability model, which is expressed as:

[0113]

[0114] in, is the observation probability of the i-th star spot pixel; and are the mean and standard deviation of the Gaussian probability model of the i-th star spot, respectively, which are obtained from the statistical characteristics of the spot and are used to represent the average value and dispersion of the star spot area in the relevant calculation results.

[0115] (5) Based on the observation probability of the star spots constructed in step (4), the joint observation probability of all star spots in the image is established using the joint probability method.

[0116] In this embodiment, it is assumed that the star spots may be located on any pixel of the image. In this case, the combination of star spots in the image will bring huge computational complexity. In order to reduce the computational complexity, the combined observation of star spots in the image is established in two steps. Specifically, first, according to the observation probability of star spots established in step (4), possible star spot candidate areas are screened out, which can be described as:

[0117]

[0118] in, Obtained from step (4), it represents the observation probability of the star spot at each position, is the threshold value constructed according to the observation probability. The above formula can be used to screen out possible candidate areas of star spots. Based on the screened candidate areas of star spots, the joint observation probability of all star spots in the image is established using the joint probability method, which is expressed as:

[0119]

[0120] in, represents the joint observation probability of all star spots in the current frame image, Indicates The observation probability of a star spot is obtained by step (4).

[0121] (6) Select another set of motion information combinations from the motion information combination sequence constructed in step (2), and repeat steps (3) to (5) until all motion information combinations are traversed, and the joint observation probability of the corresponding star spot under each motion information combination is obtained, which is recorded as , indicating the The joint observation probability of the corresponding star spots under the combination of group motion information.

[0122] (7) Reset the step range according to the predicted direction of motion of the star spot to reduce the number of motion information combinations in step (6).

[0123] In this embodiment, the motion information combination in step (6) is cut down by constructing constraint conditions to reduce the amount of calculation. The constructed constraint conditions are specifically: the step range is determined according to the predicted motion direction of the star light spot, wherein the predicted motion direction of the star light spot is obtained by step (3). Specifically, there is a certain interval between the pixels of the star sensor imaging chip, and the star light spots in different directions can only be distinguished if the interval is at least 1 pixel different in the edge area. Figure 5 As shown in the figure. Based on this feature, the motion direction of the star spot is predicted according to the constraint of one pixel in the edge area. When the position and matrix size are determined, the motion direction of the star spot is only determined by the motion rate. Therefore, the step range is set based on this feature. That is, the step range is determined according to the predicted motion direction of the star spot. By resetting the step range, the combination sequence of the three-axis motion information of the star sensor can be re-determined to achieve the minimum motion information combination and the reduction of the calculation amount.

[0124] (8) Based on the remaining motion information combination after the trimming in step (7), the optimal motion information is determined according to the joint observation probability of the corresponding star spots to detect the star spots.

[0125] Furthermore, the optimal motion information is obtained by the following method: by finding the maximum joint observation probability among the joint observation probabilities of the star spots corresponding to the motion information combinations remaining after the clipping in step (7), and determining the optimal motion information of the star sensor according to the motion information combination corresponding to the maximum joint observation probability.

[0126] Specifically, according to the joint observation probability of star spots obtained under different motion information combinations traversed in step (6), the motion information combination corresponding to the largest joint observation probability is closest to the actual motion state of the star sensor. In the correlation calculation results under this motion information combination, the star spots are detected by the threshold method. The results are as follows: Figure 6 As shown, Figure 6 (a) is a star image with a rate of 10° / s and an exposure time of 100ms. The extraction result of this star image is as follows: Figure 6 As shown in (b) in the figure. Optimal motion information It can be obtained by the following formula:

[0127]

[0128] Among them, the star spot detection can be obtained by the following formula:

[0129]

[0130] in, represents the four-connected domain operation, is a local threshold constructed based on the correlation calculation results, A collection of detected star spot pixels.

[0131] Corresponding to the above-mentioned embodiment of the method for processing a dynamic star map of a star sensor assisted by a gyroscope, the present invention further provides an embodiment of a device for processing a dynamic star map of a star sensor assisted by a gyroscope.

[0132] See also Figure 7 An embodiment of the present invention provides a gyro-assisted star sensor dynamic star map processing device, comprising one or more processors and a memory, wherein the memory is coupled to the processor; wherein the memory is used to store program data, and the processor is used to execute the program data to implement the gyro-assisted star sensor dynamic star map processing method in the above embodiment.

[0133] The embodiment of the dynamic star map processing device of the star sensor assisted by a gyro can be applied to any device with data processing capability, and the device with data processing capability can be a device or apparatus such as a computer. The device embodiment can be implemented by software, or by hardware or a combination of software and hardware. Taking software implementation as an example, as a device in a logical sense, the processor of any device with data processing capability reads the corresponding computer program instructions in the non-volatile memory into the internal memory and runs them. From the hardware level, if Figure 7 As shown in the figure, it is a hardware structure diagram of any device with data processing capability where the gyro-assisted star sensor dynamic star map processing device of the present invention is located. Figure 7 In addition to the processor, memory, network interface, and non-volatile memory shown, any device with data processing capabilities in which the apparatus in the embodiments is located may also include other hardware, generally based on the actual functions of the device with data processing capabilities, which will not be described in detail.

[0134] The implementation process of the functions and effects of each unit in the above-mentioned device is specifically described in the implementation process of the corresponding steps in the above-mentioned method, and will not be repeated here.

[0135] For the device embodiment, since it basically corresponds to the method embodiment, the relevant parts can refer to the partial description of the method embodiment. The device embodiment described above is only schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of the present invention. Ordinary technicians in this field can understand and implement it without paying creative work.

[0136] The embodiment of the present invention further provides a computer-readable storage medium on which a program is stored. When the program is executed by a processor, the method for processing a dynamic star map of a star sensor based on gyro assistance in the above embodiment is implemented.

[0137] The computer-readable storage medium may be an internal storage unit of any device with data processing capability described in any of the aforementioned embodiments, such as a hard disk or a memory. The computer-readable storage medium may also be any device with data processing capability, such as a plug-in hard disk, a smart media card (SMC), an SD card, a flash card, etc. equipped on the device. Furthermore, the computer-readable storage medium may also include both an internal storage unit of any device with data processing capability and an external storage device. The computer-readable storage medium is used to store the computer program and other programs and data required by any device with data processing capability, and may also be used to temporarily store data that has been output or is to be output.

[0138] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the present invention. After reading the above content, it will be apparent to those skilled in the art that various modifications and substitutions of the present invention will occur. Therefore, the protection scope of the present invention should be limited by the appended claims.

Claims

1. A gyro-assisted star sensor dynamic star map processing method, characterized in that: The following steps are involved: (1) Estimate the motion information of the star sensor in the current frame based on the gyro information, obtain the estimated error of the star sensor motion information based on the gyro measurement error, and establish the motion information value range of the star sensor estimated based on the gyro information according to the motion information of the star sensor in the current frame and the estimated error of the star sensor motion information; (2) Establishing a combined sequence of the three-axis motion information of the star sensor based on the motion information range of the star sensor; (3) selecting a set of motion information combinations from the combined sequence of motion information constructed in step (2), and constructing predicted images of star spot imaging at different positions within the field of view of the star sensor based on the selected motion information; (4) constructing the observation probability of the star spot based on the predicted image of the star spot imaging constructed in step (3); (5) Based on the observation probability of the star spots constructed in step (4), the joint observation probability of all star spots in the image is established using the joint probability method; (6) Select another set of motion information combinations from the motion information combination sequence constructed in step (2), and repeat steps (3) to (5) until all motion information combinations are traversed to obtain the joint observation probability of the corresponding star spot under each motion information combination; (7) Resetting the stepping range according to the predicted motion direction of the star spot to reduce the number of motion information combinations in step (6); (8) Based on the remaining motion information combination after the trimming in step (7), the optimal motion information is determined according to the joint observation probability of the corresponding star spots to detect the star spots.

2. The method for processing a dynamic star map of a star sensor based on gyro assistance according to claim 1, characterized in that: In the step (1), estimating the motion information of the star sensor in the current frame according to the gyro information specifically includes: The gyro information is the three-axis motion information measured by the gyro, expressed as ,in , and They represent the movement rates of the x-axis, y-axis, and z-axis measured by the gyroscope, respectively, and the superscript T represents the transpose of the matrix; The three-axis motion information of the star sensor in the current frame is estimated based on the three-axis motion information measured by the gyroscope, which is expressed as: ； in, Represents the three-axis motion information of the star sensor, , , They represent the movement rates of the star sensor along the x-axis, y-axis, and z-axis respectively.

3. The method for processing a dynamic star map of a star sensor based on gyro assistance according to claim 1, characterized in that: In the step (1), the estimated error of the star sensor motion information is obtained based on the measurement error of the gyroscope, which is obtained by the following formula: ； ； ； in, The estimated error matrix representing the star sensor motion information; represents the measurement error matrix of the gyroscope, , and Respectively represent the measurement errors of the gyroscope on the x-axis, y-axis and z-axis; The Jacobian matrix representing the error in the estimation of the star sensor motion information.

4. The method for processing a dynamic star map of a star sensor based on gyro assistance according to claim 1, characterized in that: In the step (2), establishing a combination sequence of the three-axis motion information of the star sensor according to the motion information value range of the star sensor specifically includes: In the motion information value range of the star sensor, the step range is set to determine the combination sequence of the three-axis motion information of the star sensor, which is expressed as: ； in, The combination of the three-axis motion information of the star sensor Axis speed combination Rate, Axis speed combination Rate and Axis speed combination rate, , and The speed combinations around the x-axis, y-axis and z-axis in the combination of the three-axis motion information of the star sensor are respectively , and rate.

5. The method for processing a dynamic star map of a star sensor based on gyro assistance according to claim 1, characterized in that: In step (3), the predicted image of the star spot imaging is represented by a matrix M, where M is a matrix containing The element values ​​in the matrix M are described by the following formula: ； in, is a set of elements with value 1 passing through the center of the matrix, for Middle The element values ​​of the elements represent star spots. The angle between the straight line formed by them and the horizontal direction defines the direction of the predicted image of the star spot imaging, that is, the direction of the star spot movement; the number of these elements defines the length of the star spot, and the length of a single side of the matrix M is taken as m.

6. The method for processing dynamic star images of a star sensor based on gyro assistance according to claim 1, characterized in that: In the step (4), constructing the observation probability of the star spot based on the predicted image of the star spot imaging constructed in step (3) specifically includes: First, the correlation between the predicted image of star spot imaging and the collected original image is calculated, which is expressed as: ； in, represents the original image collected, M represents the predicted image of star spot imaging, and G represents the correlation calculation result; Then, the observation probability of the i-th star spot pixel is constructed according to the Gaussian probability model, which is expressed as: ； in, is the observation probability of the i-th star spot pixel, and are the mean and standard deviation of the Gaussian probability model of the i-th star spot, Represents the gray value of the i-th star spot pixel after correlation calculation.

7. The method for processing dynamic star images of a star sensor based on gyro assistance according to claim 1, characterized in that: In step (5), the joint observation probability of all star spots in the image is expressed as: ； in, represents the joint observation probability of all star spots in the current frame image, Indicates The probability of observing a star spot.

8. The method for processing dynamic star images of a star sensor based on gyro assistance according to claim 1, characterized in that: In step (8), the optimal motion information is obtained by the following method: The maximum joint observation probability is found among the joint observation probabilities of the star spots corresponding to the remaining motion information combinations after the pruning in step (7), and the optimal motion information of the star sensor is determined according to the motion information combination corresponding to the maximum joint observation probability.

9. A gyro-assisted star sensor dynamic star map processing device, comprising one or more processors and a memory, characterized in that: The memory is coupled to the processor; wherein the memory is used to store program data, and the processor is used to execute the program data to implement the gyro-assisted star sensor dynamic star map processing method according to any one of claims 1 to 8.

10. A computer-readable storage medium, characterized in that: A program is stored thereon, and when the program is executed by a processor, it is used to implement the gyro-assisted star sensor dynamic star map processing method described in any one of claims 1 to 8.

Images