All-time star sensor system and anti-noise optical lens assembly

Abstract

The invention relates to the technical field of star sensors, in particular to an all-time star sensor system and an anti-noise optical lens assembly. The system comprises a star map processing unit, an intelligent control unit and a data processing unit. According to the invention, the star map processing unit is combined with the starlight signal, the imaging processing is carried out according to the starlight signal, the stray light interference is removed by using the weak, small and multi-target rapid extraction algorithm, the weak target energy is enhanced through the multi-scale operation, and the area with low brightness or high brightness in the image can be highlighted. And the data processing unit is used for carrying out recognition processing on the numerical star map by adopting a rapid autonomous star map recognition algorithm to determine attitude information of the carrying equipment, so that the star map can be recognized more accurately, and the accuracy of star map recognition is improved.

Description

Technical Field

[0001] The invention relates to the technical field of star sensors, and in particular to an all-day star sensor system and an anti-noise optical lens assembly. Background Art

[0002] A star sensor is a high-precision attitude-sensitive measuring instrument. It uses stars as a reference system, can provide accurate spatial orientation and reference, and has the advantages of high precision, strong anti-interference, and independent navigation without relying on other systems. Traditional star sensors are generally used for the navigation of spacecraft such as satellites, spacecraft, and rockets. In recent years, with the continuous development of satellite-inertial combined navigation technology, some foreign institutions have begun to try to apply star sensor technology on platforms such as long-range strategic bombers, critical space vehicles, and warships. Star sensor navigation technology has expanded from simple space applications to near-ground applications (mainly in the stratosphere with an altitude of 12 to 50 kilometers) and even sea level applications. Star sensors have an irreplaceable and important position in the field of autonomous navigation.

[0003] Under the guidance of information warfare thinking, any information leakage in war may lead to enemy attacks. In addition, the anti-interference ability of the weapon system itself is also crucial. As an important component of most weapon systems, the navigation system must also adapt to the requirements of information warfare. However, the traditional navigation methods currently in common use are vulnerable to attack, the signals are easily interfered with, and the radio will expose radiation energy during wartime. Although the inertial navigation system can work autonomously, its accuracy will drift over time and is not suitable for long-term work. Star sensors can make up for these problems. Through satellite-inertial combined guidance or starlight guidance, the accuracy and reliability of navigation can be greatly improved. If star sensors can be applied within the atmosphere, the battlefield survivability of weapon systems such as aircraft, ships, and missiles can be improved.

[0004] At present, the development of star sensors in my country is still in the development stage. Limited by foreign technology blockades, the attitude measurement accuracy of imported star sensors is generally only about 10", which is difficult to meet the requirements of high-precision measurement. It is urgent to develop high-precision star sensors to improve the accuracy of attitude measurement. Taking remote sensing mapping satellites as an example, the ground measurement error is directly related to the attitude measurement accuracy of the satellite, and the star sensor is a key component that determines the satellite positioning accuracy. Assuming that the ground positioning accuracy of the satellite camera is required to reach 50m, the satellite orbit altitude is assumed to be 600km, and considering other system errors of the satellite, the satellite's attitude control system requires the attitude measurement accuracy of the star sensor to reach about 1.7". If the star sensor accuracy does not reach this level, it will affect the accuracy of the mapping data. The same problem also exists for some near-ground platforms. For example, the ship attitude measurement of my country's space measurement ship depends on the inertial navigation system, and the use of star sensors and inertial navigation combined measurement can greatly improve the system accuracy, but the corresponding accuracy is difficult to achieve high-precision measurement. Summary of the invention

[0005] The object of the present invention is to provide a full-time star sensor system and an anti-noise optical lens assembly, which can extract the characteristics of observed stars according to multiple aspects, identify star maps more accurately, and improve the accuracy of star map recognition, so as to solve the problems raised in the above-mentioned background technology.

[0006] To achieve the above object, one of the objects of the present invention is to provide a full-time star sensor system, including an optical system and a star sensor electronic control system; The optical system includes a star map collection unit and a star map processing unit. The star map collection unit is configured with a lens assembly, a photosensitive detector and a processing circuit. The lens assembly cooperates with the photosensitive detector to collect starlight signals, and the processing circuit is used to transmit the starlight signals to the star map processing unit. The star map processing unit is used to combine the starlight signals, perform imaging processing according to the starlight signals, and remove stray light interference using a weak, small, and multi-target fast extraction algorithm; The star sensor electronic control system includes an intelligent control unit, a data processing unit and a data communication unit; The data processing unit is used to send control instructions to the active pixel sensor in the intelligent control unit, the active pixel sensor generates a driving signal required for A / D conversion, performs photoelectric conversion on the starlight signal, generates a digital star map, performs discrete sampling on the digital star map, and finally reads out and stores the digital star map; The data communication unit exchanges information with the carrier controller and the carrier telemetry system through the onboard controller, and transmits the instructions in the controller to the data processing unit to control the operation of the active pixel sensor, process the digital star map, and determine the attitude information of the onboard device by identifying and processing the numerical star map.

[0007] As a further improvement of the technical solution, the photosensitive detector in the star map acquisition unit is a SCMOS sensor.

[0008] As a further improvement of the technical solution, the method of the weak, small, and multi-target fast extraction algorithm in the star map processing unit includes the following steps: S201, extracting the bright and dark area features in the preliminarily processed star map using Top-hat transformation; S202, enhancing the contrast of the image by using histogram homogenization; S203, dispersing the grayscale levels of the histogram of the image from being concentrated in a small part of the grayscale levels to covering all the grayscale levels; S204, obtaining the brightest and darkest pixel values ​​in the image and mapping them to pure black and pure white, and then mapping other pixel values ​​to values ​​between pure black and pure white according to an algorithm; S205, matching corresponding connectivity criteria according to the shape of the image; S206, obtaining the number of targets in the image and the area of ​​each target through connectivity analysis, and calculating the centroid of the star point targets in the image; S207, controlling the balance between the expansion and erosion effects by customizing weight parameters to obtain an optimized image.

[0009] As a further improvement of the present technical solution, the centroid calculation in S206 adopts a pixel calculation algorithm, and its algorithm formula is as follows: ; in, Indicates the pixel position of a target in the image, S represents The value range of Pixel The pixel value of Represents the centroid coordinates.

[0010] As a further improvement of the technical solution, the custom weight in S207 adopts a weight parameter algorithm, and its algorithm formula is as follows: ; in, is the expanded image, is the image after corrosion, and is the weighting parameter, and .

[0011] As a further improvement of the technical solution, the data processing unit adopts a fast autonomous star map recognition algorithm for identifying the numerical star map, and the steps are as follows: S401, filtering the star map to obtain the field star targets in the star map; S402, combining the astronomical star catalog and the navigation star catalog to form a navigation star library in the process of star map recognition; S403, extracting the observed star features in the field of view star target, and performing feature analysis in combination with the navigation star library; S404: Use recognition and comparison algorithms to identify corresponding features and display the results.

[0012] As a further improvement of the technical solution, the method for obtaining the field star target in the star map in S401 includes the following steps: S4011, judging whether the starry sky illumination in the star map is uniform, and extracting star points by using a threshold segmentation method; When the starry sky illumination in the star map is uniform, the bimodal method with global threshold is used; When the starry sky illumination in the star map is uneven, the local threshold method is used; S4012, obtaining star points segmented by the threshold segmentation method, and obtaining image coordinates of the star points; S4013, converting the star point coordinates from the image coordinate system to the corresponding celestial coordinates, and establishing the coordinate relationship of the star point in the image coordinate system and in the star sensor coordinate system according to the visual projection relationship; S4014. Mark the star points.

[0013] As a further improvement of the technical solution, extracting the observed star features in the field star target in S403 includes identifying the geometric relationship and brightness relationship between the stars, and the geometric relationship includes distance and angle.

[0014] The second object of the present invention is to provide a lens assembly for use with an all-day star sensor system, including a lens and a sunshade. The lens adopts an eight-piece double Gaussian structure, and the aperture is moved to the first lens. The plane reflector is located at the front end of the lens, and the sunshade is arranged on the front side of the lens.

[0015] Compared with the prior art, the present invention has the following beneficial effects: In this all-day star sensor system and anti-noise optical lens assembly, the starlight signal is combined with the star map processing unit, and imaging processing is performed according to the starlight signal. The weak, small, and multi-target fast extraction algorithm is used to remove stray light interference. Multi-scale operations enhance the energy of weak targets and can highlight areas with lower or higher brightness in the image.

[0016] The data processing unit uses a fast autonomous star map recognition algorithm to identify and process the numerical star map, which can quickly determine the attitude information of the onboard equipment and reduce the system response time. At the same time, it can extract the observed star features based on multiple aspects, identify the star map more accurately, and improve the accuracy of star map recognition. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is the overall system block diagram of the present invention; Figure 2 The working principle diagram of the SCMOS sensor of the present invention; Figure 3 It is a flowchart of the high dynamic range imaging technology of the present invention; Figure 4 It is a simulation diagram of the four-way criterion of the present invention; Figure 5 It is a simulation diagram of the eight-link criterion of the present invention; Figure 6 This is a simulation diagram of the fast autonomous star map recognition algorithm of the present invention; Figure 7 It is a structural plan view of the lens assembly of the present invention; Figure 8 This is a simulation diagram of the lens position of the present invention.

[0018] The meaning of each number in the figure is: 10. Star map acquisition unit; 20. Star map processing unit; 30. Intelligent control unit; 40. Data processing unit; 50. Data communication unit. DETAILED DESCRIPTION

[0019] The following will be combined with the accompanying drawings in the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] See also Figure 1 As shown, one of the purposes of the present invention is to provide a full-time star sensor system, including an optical system and a star sensor electronic control system; The optical system includes a star map collection unit 10 and a star map processing unit 20. The star map collection unit 10 is configured with a lens assembly, a photosensitive detector and a processing circuit. The lens assembly cooperates with the photosensitive detector to collect starlight signals, and the processing circuit is used to transmit the starlight signals to the star map processing unit 20. The star map processing unit 20 is used to combine the starlight signals, perform imaging processing according to the starlight signals, and remove stray light interference by using a weak, small, and multi-target fast extraction algorithm. The star sensor electronic control system includes an intelligent control unit 30 , a data processing unit 40 and a data communication unit 50 .

[0021] Among them, the data processing unit 40 is used to send control instructions to the active pixel sensor in the intelligent control unit 30, the active pixel sensor generates the driving signal required for A / D conversion, performs photoelectric conversion on the starlight signal, generates a digital star map, and discretely samples the digital star map, and finally reads out and stores the digital star map.

[0022] The data communication unit 50 exchanges information with the carrier controller and the carrier telemetry system through the onboard controller, and transmits the instructions in the controller to the data processing unit 40 to control the operation of the active pixel sensor, process the digital star map, and determine the attitude information of the onboard device by identifying and processing the numerical star map.

[0023] During specific use, in the process of acquiring the attitude information of the mounted device, the starlight signal is first collected by the star map acquisition unit 10 through the lens assembly and the photosensitive detector, and then the starlight signal is combined with the star map processing unit 20 to perform imaging processing according to the starlight signal. Due to the large number of stars in space and the existence of other stray light interference, it is necessary to use a weak, small, and multi-target rapid extraction algorithm to remove the stray light interference.

[0024] After completing the star map collection work, since the star map imaging effect is poor at this time and accurate reference information cannot be obtained, it is necessary to send a control instruction to the active pixel sensor in the intelligent control unit 30 through the data processing unit 40, and the active pixel sensor generates the driving signal required for A / D conversion, performs photoelectric conversion on the starlight signal, generates a digital star map, and performs discrete sampling on the digital star map, and finally reads out and stores the digital star map. Figure 1 The static memory 1 and the static memory 2 shown in FIG.

[0025] During the information exchange process, the data communication unit 50 exchanges information with the carrier controller and the carrier telemetry system through the onboard controller, and transmits the instructions in the controller to the data processing unit 40 to control the work of the active pixel sensor, process the digital star map, and determine the attitude information of the onboard device by identifying and processing the numerical star map. The onboard controller includes a 1553B controller and an RS232 controller. Figure 1 As shown, the 1553B controller cooperates with the isolation transformer to connect with the carrier controller for information exchange, and the RS232 controller cooperates with the isolation circuit to interact with the carrier telemetry system, so as to establish a command transmission channel, obtain corresponding control commands, control the start-up of the active pixel sensor, and process the digital star map.

[0026] In addition, the photosensitive detector in the star map acquisition unit 10 is a SCMOS sensor.

[0027] SCMOS sensors offer high quantum efficiency, they are able to more efficiently convert incident light into photoelectrons, Figure 2 As shown, the sensor's sensitivity to light is improved, and noise can be reduced through on-chip correlated multi-sampling to improve image quality.

[0028] SCMOS sensors use large and small gain dual-path readout synthetic high dynamic range imaging technology. They can capture details from very dark to very bright in one image. The specific steps are as follows: The first step is to input multiple original image sequences with different exposures and calibrate the response curve of the lens component; The second step is to synthesize high dynamic range images, namely HDR images; The third step is to use the Tone-Mapping compression algorithm to display the processed image on the data processing board.

[0029] In addition, SCMOS sensors support high-speed imaging, can cover a larger field of view, have a highly integrated design, and have stronger environmental adaptability.

[0030] Furthermore, the method of the weak, small, and multiple target fast extraction algorithm in the star map processing unit 20 includes the following steps: S201, extracting bright and dark area features in the preliminarily processed star map using Top-hat transformation; S202, enhancing the contrast of the image by using histogram homogenization; S203, dispersing the grayscale levels of the histogram of the image from being concentrated in a small part of the grayscale levels to covering all the grayscale levels; S204, obtaining the brightest and darkest pixel values ​​in the image and mapping them to pure black and pure white, and then mapping other pixel values ​​to values ​​between pure black and pure white according to an algorithm; S205, matching corresponding connectivity criteria according to the shape of the image; S206, obtaining the number of targets in the image and the area of ​​each target through connectivity analysis, and calculating the centroid of the star point targets in the image; S207, controlling the balance between the expansion and erosion effects by customizing weight parameters to obtain an optimized image.

[0031] When used specifically, in the process of processing the quality of the star map image, the bright and dark area features in the preliminarily processed star map are first extracted through Top-hat transformation, and the white and black Top-hat transformations are used to enhance the energy of weak targets through multi-scale operations. White Top-hat transformation and Black Top-hat transformation obtain objects in the original image that are brighter and darker than the neighborhood covered by their structural elements. They can extract detailed targets that are brighter and darker than the background, and at the same time enhance the details such as edges and textures in the image. Multiple Top-Hat operations are performed using structural elements of different sizes, and information of different scales is integrated. The extracted results are superimposed according to a certain weight to enhance the target details.

[0032] Then use histogram to equalize the image to enhance the contrast of the image. The grayscale level of the image's histogram is dispersed from being concentrated in a small part of the grayscale level to having a certain coverage of all grayscale levels. After finding the brightest and darkest pixel values ​​in the image and mapping them to pure black and pure white, the other pixel values ​​are mapped to values ​​between pure black and pure white according to the algorithm. Or find the average value of the pixels in the image as the middle grayscale value, and then expand the range to achieve as full a display value as possible. Finally, combine the image after histogram equalization with the original image to enhance the contrast of the entire image and the visibility of weak targets.

[0033] Then, the corresponding connectivity criterion is matched according to the shape of the image. Figure 4 and Figure 5 As shown in the figure, when the star map is a convex target, the four-connectivity criterion method is used, and when the star map is a concave target, the eight-connectivity criterion method is used. Finally, the number of targets in the image and the area of ​​each target are obtained through connectivity analysis, and the center of mass of the star point target in the image is calculated. The balance of expansion and erosion effects is controlled by custom weight parameters to obtain the optimized image, thereby effectively suppressing background stray light and greatly improving the image contrast and the significance of the target area.

[0034] Furthermore, the centroid calculation in S206 adopts a pixel calculation algorithm, and its algorithm formula is as follows: ; in, Indicates the pixel position of a target in the image, S represents The value range of Pixel The pixel value of Represents the centroid coordinates.

[0035] Specifically, the custom weight in S207 adopts a weight parameter algorithm, and its algorithm formula is as follows: ; in, is the expanded image, is the image after corrosion, and is the weighting parameter, and .

[0036] Through the weighted superposition operation, the brightness characteristics of the target area are further highlighted, and the influence of background stray light on the overall image quality is eliminated. At the same time, in order to adapt to different light intensities and stray light distributions, the number of expansions and erosions and the size of the structural elements are dynamically adjusted. When the background light is strong, the number of operations can be increased and a larger structural element can be selected to significantly suppress the stray light; when the background light is weak or the noise is less, the use of a smaller structural element can effectively protect the boundary characteristics of the target and avoid the loss of accurate information due to excessive processing of weak and small targets. Through the above operations, the background stray light is effectively suppressed, and the contrast of the image and the saliency of the target area are greatly improved. This step significantly enhances the stability of subsequent target feature extraction and matching, and provides a solid foundation for achieving high-precision weak and small target extraction.

[0037] In addition, the data processing unit 40 uses a fast autonomous star map recognition algorithm to identify the numerical star map, and the steps are as follows: S401, filtering the star map to obtain the field star targets in the star map; S402, combining the astronomical star catalog and the navigation star catalog to form a navigation star library in the process of star map recognition; S403, extracting the observed star features in the field of view star target, and performing feature analysis in combination with the navigation star library; S404: Use recognition and comparison algorithms to identify corresponding features and display the results.

[0038] Furthermore, the method for obtaining the field star targets in the star map in S401 includes the following steps: S4011, judging whether the starry sky illumination in the star map is uniform, and extracting star points by using a threshold segmentation method; When the starry sky illumination in the star map is uniform, the bimodal method with global threshold is used; When the starry sky illumination in the star map is uneven, the local threshold method is used; S4012, obtaining star points segmented by the threshold segmentation method, and obtaining image coordinates of the star points; S4013, converting the star point coordinates from the image coordinate system to the corresponding celestial coordinates, and establishing the coordinate relationship of the star point in the image coordinate system and in the star sensor coordinate system according to the visual projection relationship; S4014. Mark the star points.

[0039] Furthermore, extracting the observed star features in the field of view star target in S403 includes identifying the geometric relationship and brightness relationship between the stars, and the geometric relationship includes distance and angle.

[0040] When used specifically, Figure 6 As shown in the figure, in the process of star map recognition, since the original star map image is seriously interfered by noise, it is necessary to process the star map through filtering, perform detail processing on the original star map, and obtain a star map with reduced noise interference. After that, the star points in the processed star map are extracted, that is, the field star targets. In the star point extraction link, this scheme adopts the threshold segmentation method to accurately segment the star points from the background based on the tiny grayscale difference between the star points and the background.

[0041] For star images with uniform sky illumination, the bimodal method with global threshold is used. This method assumes that the grayscale histogram of the image presents two obvious peaks, one corresponding to the grayscale distribution of the background, and the other corresponding to the grayscale distribution of the star points. The threshold is selected at the trough position between the two peaks, so that the star points and the background can be better separated.

[0042] For star images with uneven sky illumination, the local threshold method is used. The image is divided into multiple small sub-regions, and the threshold is calculated for each sub-region. Algorithms process data.

[0043] Then mark the segmented star points. After marking, convert the star point coordinates from the image coordinate system to the appropriate celestial coordinates. The specific process is as follows: let the optical axis direction of the star sensor be the Y axis, and the Z axis form the image plane coordinate system. According to the perspective projection relationship, establish the coordinate relationship between the star point in the image coordinate system and the star sensor coordinate system. Let the unit direction of the star point in the star sensor coordinate system be , the vector is represented as , O is the coordinate after the conversion of the internal parameters and external parameters (attitude), and the star sensor coordinate system is transformed by the rotation matrix, where is the coordinate after the conversion of internal parameters and external parameters (attitude), then , , ,in is the coordinate position of the star point, , , , , , , , as well as Complete the star point marking process for different unit directions in the star sensor coordinate system.

[0044] Then, the features of the observed stars in the field of view are extracted. The main features identified in this scheme are to calculate the geometric relationship between several stars, including distance and angle, and compare the brightness between stars to extract geometric and brightness features.

[0045] The specific process is: The first step is to calculate the length of the three sides of the triangle, set the coordinates of the three vertex points of the triangle, and calculate the length of the three sides according to the distance formula between two points; The second step is to calculate the side length ratio. The purpose of this is to eliminate the effects caused by the different field of view sizes of star sensors or the scaling of star maps. Step 3: Calculate the interior angle of the triangle based on the cosine theorem in trigonometric functions; The fourth step is to compare the three sides of the triangle to obtain the specific angle value. The angle information can further supplement the geometric features of the triangle and be used to more accurately identify the star map and improve the accuracy of star map recognition.

[0046] In addition, the brightness characteristics of the star points need to be considered: that is, the brightness of the star points at the vertices of the triangle. The brightness values ​​of the three stars are recorded, and the brightness ratio can be used as an auxiliary feature. The brightness characteristics can, to a certain extent, distinguish star charts with similar geometric shapes but different star point brightness. After processing the above data, the calculated geometric features such as the length and angle of the triangle are compared with the data in the star catalog, that is, the stored data in the navigation star library, so as to determine the star number corresponding to the star point and further determine the attitude information of the star sensor.

[0047] The second object of the present invention is to provide a lens assembly for use with an all-day star sensor system, including a lens and a light shield. The lens adopts an eight-piece double Gaussian structure, and the aperture therein is moved to the first lens. The plane reflector is located at the front end of the lens, and the light shield is arranged on the front side of the lens.

[0048] like Figure 7As shown, in specific use, since the traditional double Gauss objective lens is composed of six pieces and four groups of lenses, with a single lens and a group of double cemented lenses at the front and back, and the diaphragm is located between the two groups of double cemented lenses, it is a symmetrical structure. Although it is conducive to the correction of asymmetric aberrations, it leads to an increase in the aperture of the front group of lenses, which is not conducive to the miniaturization of the optical system. Therefore, the present invention improves the eight-piece double Gauss structure and moves the diaphragm to the first lens, which can reduce the aperture of the front group of lenses and is conducive to the elimination of stray light. The improved initial structure is shown in FIG. Figure 8 As shown, the system F number is 1.2, the field of view is 8°, Figure 8 The lines of different colors represent the projection of light sources at different positions.

[0049] The plane reflector is at the front end of the lens. The target light enters the lens assembly after being reflected by the reflector. Its surface shape has a decisive influence on the imaging quality of the entire optical system. Therefore, the present invention selects fused quartz as the material of the reflector. According to the properties of commonly used reflector materials, the thermal expansion coefficients of microcrystalline glass and fused quartz are relatively small, but for the plane reflector at the front end of the system, it is directly affected by the external temperature environment, and its temperature change is more drastic than other components. Fused quartz has the advantages of being resistant to sudden cooling and heating compared to microcrystalline glass, and it is cheap and has a smaller density. Therefore, fused quartz is more suitable as the material of the plane reflector in this optical system. When the plane reflector is made of fused quartz, the thermal expansion coefficient of indium steel in the structural material is basically the same as that of fused quartz. Therefore, the frame material is made of indium steel for processing. By combining these two materials, the plane reflector can achieve a small change in surface shape under conditions of rapid changes in high and low temperatures.

[0050] When selecting materials for the primary mirror and secondary mirror assembly in the lens, since the primary and secondary mirrors are the main components in the lens assembly, their performance directly affects the performance of the optical system. Therefore, the primary mirror and secondary mirror materials in the present invention are both made of fused quartz, and the primary mirror frame and secondary mirror frame materials are made of indium steel.

[0051] Finally, the correction lens group and filter in this optical system are all refractive elements, and the raw materials are all optical glass. Since the thermal expansion coefficient of glass material is small, the frame material is titanium alloy material with a close expansion coefficient.

[0052] At the same time, aluminum is selected as the material of the sunshade. At the same time, except for the light blocking ring, the rest of the inner wall of the sunshade is all light-shielding patterns. In order to meet the index requirements of product design, our team specifically calculated the length and aperture size of the sunshade to optimize the performance of the sunshade. The specific calculation steps are as follows: Let θ be the incident angle of the light, φ be the half-viewing angle of the incident light, x be the length of the secondary sunshade, y be the length of the primary sunshade, then x=βL, and we can get the following equations: ; ① ; ② ; ③ From the above equations ①, ② and ③, we can get ④; From d=50mm, , , put it into formula ④, and we get In this solution, L=210mm can be considered. Considering the interface between the light shield and CCD and the heat insulation problem, the total length of the light shield can be taken as L=220mm. Therefore, the maximum aperture D=50+2×220tan 5=88mm can be obtained; Considering L=210mm, and considering the interface between the hood and CCD and the heat insulation problem, the total length of the hood can be set to L=220mm. Therefore, the maximum aperture D=50+2×220tan 5=88mm.

[0053] During specific use, the lens is used to collect target light, and the photosensitive detector is located at the end of the lens. After the target light passes through the optical system formed by the lens, it forms incident light and is transmitted to the photosensitive detector. The photosensitive detector converts the incident light into photoelectrons, collects starlight signals, and uses the processing circuit to transmit the starlight signals to the star map processing unit 20. At the same time, the sunshade forms a cover on the front side of the lens to avoid interference from stray light such as sunlight and ground light.

[0054] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and descriptions are only preferred examples of the present invention and are not intended to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. An all-day star sensor system, characterized in that: Including optical system and star sensor electronic control system; The optical system comprises a star map collection unit (10) and a star map processing unit (20); the star map collection unit (10) is configured with a lens assembly, a photosensitive detector and a processing circuit; the lens assembly cooperates with the photosensitive detector to collect starlight signals, and the processing circuit transmits the starlight signals to the star map processing unit (20); the star map processing unit (20) is used to combine the starlight signals, perform imaging processing according to the starlight signals, and remove stray light interference using a weak, small, and multi-target rapid extraction algorithm; The star sensor electronic control system comprises an intelligent control unit (30), a data processing unit (40) and a data communication unit (50); The data processing unit (40) is used to send a control instruction to the active pixel sensor in the intelligent control unit (30); the active pixel sensor generates a driving signal required for A / D conversion, performs photoelectric conversion on the starlight signal, generates a digital star map, performs discrete sampling on the digital star map, and finally reads out and stores the digital star map; The data communication unit (50) exchanges information with the carrier controller and the carrier telemetry system through the onboard controller, and transmits instructions in the controller to the data processing unit (40), controls the operation of the active pixel sensor, processes the digital star map, and determines the attitude information of the onboard device by identifying and processing the numerical star map.

2. The all-day star sensor system according to claim 1, characterized in that: The photosensitive detector in the star map acquisition unit (10) is a SCMOS sensor.

3. The all-day star sensor system according to claim 1, characterized in that: The method of the weak, small, and multiple target fast extraction algorithm in the star map processing unit (20) comprises the following steps: S201, extracting the bright and dark area features in the preliminarily processed star map using Top-hat transformation; S202, enhancing the contrast of the image by using histogram homogenization; S203, dispersing the grayscale levels of the histogram of the image from being concentrated in a small part of the grayscale levels to covering all the grayscale levels; S204, obtaining the brightest and darkest pixel values ​​in the image and mapping them to pure black and pure white, and then mapping other pixel values ​​to values ​​between pure black and pure white according to an algorithm; S205, matching corresponding connectivity criteria according to the shape of the image; S206, obtaining the number of targets in the image and the area of ​​each target through connectivity analysis, and calculating the centroid of the star point targets in the image; S207, controlling the balance between the expansion and erosion effects by customizing weight parameters to obtain an optimized image.

4. The all-day star sensor system according to claim 3, characterized in that: The centroid calculation in S206 adopts a pixel calculation algorithm, and its algorithm formula is as follows: ； in, Indicates the pixel position of a target in the image, S represents The value range of Pixel The pixel value of Represents the centroid coordinates.

5. The all-day star sensor system according to claim 1, characterized in that: The custom weight in S207 adopts a weight parameter algorithm, and the algorithm formula is as follows: ； in, is the expanded image, is the image after corrosion, and is the weighting parameter, and .

6. The all-day star sensor system according to claim 1, characterized in that: The data processing unit (40) uses a fast autonomous star map recognition algorithm to identify the numerical star map, and the steps are as follows: S401, filtering the star map to obtain the field star targets in the star map; S402, combining the astronomical star catalog and the navigation star catalog to form a navigation star library in the process of star map recognition; S403, extracting the observed star features in the field of view star target, and performing feature analysis in combination with the navigation star library; S404: Use recognition and comparison algorithms to identify corresponding features and display the results.

7. The all-day star sensor system according to claim 6, characterized in that: The method for obtaining the field star targets in the star map in S401 comprises the following steps: S4011, judging whether the starry sky illumination in the star map is uniform, and extracting star points by using a threshold segmentation method; When the starry sky illumination in the star map is uniform, the bimodal method with global threshold is used; When the starry sky illumination in the star map is uneven, the local threshold method is used; S4012, obtaining star points segmented by the threshold segmentation method, and obtaining image coordinates of the star points; S4013, converting the star point coordinates from the image coordinate system to the corresponding celestial coordinates, and establishing the coordinate relationship of the star point in the image coordinate system and in the star sensor coordinate system according to the visual projection relationship; S4014. Mark the star points.

8. The all-day star sensor system according to claim 6, characterized in that: Extracting the observed star features in the field star target in S403 includes identifying the geometric relationship and brightness relationship between the stars, wherein the geometric relationship includes distance and angle.

9. A lens assembly for use with the all-weather star sensor system of claim 1, characterized in that: The invention comprises a lens and a light shield, wherein the lens adopts an eight-piece double Gauss structure, and the aperture thereof is moved to the first lens, wherein the plane reflector is located at the front end of the lens, and the light shield is arranged at the front side of the lens.

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