Wide area infrared point target detection and tracking satellite system

Abstract

The application provides a wide-area infrared point target detection tracking cooperative satellite system, which comprises a camera subsystem, a target processing subsystem, a task planning subsystem, an intersatellite network subsystem, an imaging quality guarantee subsystem and a light shield subsystem; the camera subsystem is used for imaging infrared point targets in a wide-area range to generate a wide-area monitoring range image containing weak infrared radiation targets; the target processing subsystem extracts two-dimensional plane coordinates of the targets from the infrared image, generates three-dimensional positions and speeds of the targets, and reasonably distributes different targets to different satellites for data fusion; the task planning subsystem calculates orbit positions and observation capabilities of other cooperative satellites according to the three-dimensional positions of the targets, and performs observation task planning on the other cooperative satellites; the intersatellite network subsystem is responsible for receiving two-dimensional angular trajectories provided by other satellites, providing the two-dimensional angular trajectories to the target processing subsystem, and sending information such as cooperative planning generated by the task planning subsystem to other satellites.

Description

Technical Field

[0001] This invention belongs to the field of optical satellite remote sensing for Earth imaging, and specifically relates to a geosynchronous orbit wide-area infrared point target detection and tracking cooperative satellite system. Background Technology

[0002] Wide-field infrared point target detection is an important application of optical remote sensing satellites. Current wide-field infrared point target detection satellite systems mainly employ linear array payloads, using the infrared spectral band to scan and image targets with high infrared radiation intensity. The targets detected in the infrared images are point targets, lacking distinct geometric shapes. After target detection, tracking is performed using a small-area array staring payload, which presents the following main problems:

[0003] (1) It cannot simultaneously meet the requirements for wide-area detection range and weak radiation target detection. The linear array system has poor detection sensitivity and cannot effectively detect weak infrared radiation targets below kilowatt / steradian. In addition, the linear array imaging system achieves detection through scanning, which has a long scanning cycle and can acquire a small number of target samples, making it easy to lose targets. The small area array staring system has a small field of view, generally around 1°×1°, which cannot meet the requirements for effective tracking of targets in a wide area.

[0004] (2) After the infrared image data is generated, the target detection software generates two-dimensional planar position information of the point target. Then, by fusing the two-dimensional planar target information generated by at least two satellites, the three-dimensional trajectory information of the target is generated. Currently, this function is mainly completed by the ground system. The satellite can only fuse information of a small number of targets, such as about three, which cannot meet the usage requirements.

[0005] (3) Currently, the wide-area infrared point target detection satellite system mainly relies on the ground for mission planning and information exchange. The satellite does not have mission planning capabilities or an inter-satellite information transmission network. It cannot cooperate with other satellites or other ground users to carry out work. When cooperating with other satellites, it mainly relies on the ground command and control system, resulting in low timeliness and system joint operation efficiency.

[0006] (4) Infrared point target detection satellites need to block sunlight entering the lens. If blocking is not possible, avoidance measures must be taken. The satellite cannot work when sunlight is avoided. Currently, sunshades or cylindrical sunshades are generally used to block sunlight. The longest time the satellite is not working in a single day is up to 4 hours, which severely limits the satellite's usable time. Summary of the Invention

[0007] In view of this, the present invention provides a wide-area infrared point target detection and tracking collaborative satellite system, which can provide stronger detection and assessment capabilities for weak infrared point targets. The system includes: a camera subsystem, a target processing subsystem, a mission planning subsystem, an inter-satellite network subsystem, an imaging quality assurance subsystem, and a sunshade subsystem. The camera subsystem is used to image infrared point targets over a wide area, generating a wide-area surveillance image including targets with weak infrared radiation, and providing the image data to the target processing subsystem. The target processing subsystem extracts the two-dimensional planar coordinates of the targets from the infrared image, generates the three-dimensional position and velocity of the targets, and rationally allocates different targets. The system integrates data from different satellites; the mission planning subsystem calculates the orbital positions and observation capabilities of other cooperating satellites based on the target's three-dimensional position, and plans observation missions for these satellites; the inter-satellite network subsystem receives two-dimensional angular trajectories from other satellites and provides them to the target processing subsystem, while simultaneously sending collaborative planning information generated by the mission planning subsystem to other satellites; the imaging quality assurance subsystem provides high-precision deformation measurement results from the satellite, and, combined with onboard autonomous geometric calibration, provides high-precision geometric calibration coefficients for dual-satellite data fusion; the sunshade subsystem, located outside the camera, combines with the satellite's autonomous sunlight avoidance strategy to suppress and isolate incident light.

[0008] Specifically, the camera subsystem includes an infrared camera, an electronics processor, and a refrigerator. The infrared camera employs a large-aperture, deep-temperature, transmission-type optical system. Its optical structure consists of multiple Gaussian aspherical lenses, providing an arbitrary selectable detection field of view within the range of 0°×0° to 25°×25°. The camera's focal plane is composed of a large-area infrared detector array. The electronics processor performs radiometric correction on the infrared image, generates raw image data according to a specified data format, and transmits it to the target processing subsystem. The refrigerator is a pulse tube refrigerator, with its long-term shaded side located in the satellite's X-axis direction, facing deep space, providing radiative cooling to the large-area infrared detector array.

[0009] Specifically, the target processing subsystem includes a target detection module, an autonomous geometric calibration module, and a data fusion module. The target detection module extracts the two-dimensional trajectory of point targets in the infrared image through a target detection algorithm. The autonomous geometric calibration module determines the positions of typical feature points in the infrared image and provides geometric calibration coefficients in real time. The data fusion module fuses the two-dimensional planar position information of the two satellites into three-dimensional position and velocity information. At the same time, it uses a dynamic optimization fusion allocation algorithm based on the observation area to allocate the fusion calculation of multiple targets to different satellites for fusion.

[0010] Specifically, the mission planning subsystem connects and interacts with the inter-satellite network subsystem, including a target threat priority assessment module, a resource scheduling module, and a conflict resolution module. The target threat priority assessment module assesses the target priority based on the three-dimensional position and velocity information of the point target obtained by the target processing subsystem. The resource scheduling module schedules other satellites and ground facilities with collaborative capabilities according to the target priority. When conflicts occur in the scheduling of other resources, the conflict resolution module is responsible for coordination.

[0011] Specifically, the inter-satellite network subsystem includes inter-satellite laser communication equipment, inter-satellite Ka phased array communication equipment, and inter-satellite network management equipment; the inter-satellite laser communication equipment is used to communicate with other satellites with high data exchange needs; the inter-satellite Ka communication equipment is used to communicate with satellites with general data needs; and the inter-satellite network management equipment is used to complete the conversion of communication protocols between different satellites, the operation and maintenance of the inter-satellite network, and data transmission routing.

[0012] Specifically, the imaging quality assurance subsystem includes an angular displacement measuring instrument, which is integrated with the camera subsystem to measure on-orbit thermal deformation and camera line-of-sight jitter. Based on the optical lever method of optical autocollimation principle, the laser emitted by the laser angle measuring instrument is reflected back after passing through the reflective surface of the central reference component. By measuring the coordinate deviation of the zero position and the offset position of the reflected light, the angular displacement of the camera in the azimuth and elevation directions can be solved respectively, and finally accurate thermal deformation data can be obtained.

[0013] Specifically, the sunshade subsystem is installed outside the camera subsystem. According to the satellite's autonomous sunlight avoidance strategy, during installation, the sunshade's light-blocking side must be aligned with the direction of sunlight incidence. This sunlight avoidance strategy ensures the sunshade continuously blocks sunlight. The sunshade includes a light-blocking film and a lightweight, deployable frame, which is in a compressed state during launch to meet the space requirements of the launch vehicle fairing. After in-orbit operation, the sunshade is deployed, specifically through a three-dimensional, two-stage deployment: first, a passive drive method for lateral deployment, followed by a sleeve deployment mechanism for longitudinal deployment.

[0014] Beneficial effects:

[0015] (1) Compared with the prior art, the present invention can provide a stronger detection capability for weak infrared point targets, increasing the detection capability from tens of thousands of W / sr to hundreds of W / sr. At the same time, the present invention can provide wide-area surveillance capability. In geosynchronous orbit, the detection range of a single satellite for weak infrared point targets can reach thousands of kilometers.

[0016] (2) Compared with the prior art, the present invention can effectively allocate targets and double the number of fused targets;

[0017] (3) Existing ground geometric calibration requires separate calibration observations for each calibration, which takes more than half an hour each time. The calibration coefficients are updated on a daily cycle. This invention achieves autonomous real-time geometric calibration on the satellite, eliminating the need for separate ground calibration observations. The on-board calibration coefficients are updated on the second level.

[0018] (4) Compared with the prior art, the present invention realizes the integration of detection and tracking coordination, and does not require external guidance information for task planning;

[0019] (5) Compared with the prior art, the present invention significantly improves the satellite working time, reducing the unusable time per day from a maximum of 4 hours to less than 30 minutes.

[0020] This invention provides a wide-area infrared point target detection and tracking collaborative satellite system, systematically solving the problem of effective detection of weak infrared radiation point targets over a wide area. It overcomes the shortcomings of on-board infrared point target processing and autonomous collaboration, achieving integrated satellite imaging detection, target detection, trajectory fusion, mission planning, and information distribution without requiring ground-based intervention. Based on an autonomous sunlight avoidance strategy using a high-ratio flexible deployable sunshade, it reduces the impact of sunlight on satellite availability, significantly improving satellite operational efficiency. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the composition of the wide-area infrared point target detection and tracking collaborative satellite system of the present invention;

[0022] Figure 2 This is a schematic diagram of the camera optical system mechanism of the present invention. Detailed Implementation

[0023] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0024] This invention provides a wide-area infrared point target detection and tracking collaborative satellite system. The main components of the satellite system include: ① a camera subsystem, ② a target processing subsystem, ③ a mission planning subsystem, ④ an inter-satellite network subsystem, ⑤ an imaging quality assurance subsystem, and ⑥ a sunshade subsystem. The main components of the satellite system are as follows... Figure 1 As shown, the details are described below.

[0025] 1. Camera Subsystem

[0026] The camera subsystem performs infrared point target imaging over a wide area, generating a wide-area surveillance image including targets with weak infrared radiation, and provides the image data to the target processing subsystem. The camera subsystem includes an infrared camera, an electronics processor, and a cryostat. The infrared camera employs a large-aperture, cryogenic transmission optical system. Its optical structure consists of multiple Gaussian aspherical lenses, providing an arbitrarily selectable detection field of view within the range of 0°×0° to 25°×25°. The camera's focal plane is composed of a large array of infrared detectors, adaptable to detectors of various sizes such as 2K×2K, 2.7K×2.7K, and 4K×4K. It has an imaging data acquisition frequency of 0–20Hz and provides a cryogenic environment of 200K–240K for the camera's optical lens through whole-satellite radiation cooling, achieving instrument noise suppression throughout the optical system's optical path. The electronics processor performs radiometric correction of the infrared image, generates raw image data according to a specified data format, and transmits it to the target processing subsystem. The cryostat uses a pulse tube cryostat to cool the large array of detectors.

[0027] The camera subsystem includes an infrared camera, an electronics processor, and a cooling system. The subsystem consists of 3-4 cameras and employs a transmissive optical system with an entrance pupil diameter greater than 300-500mm. The optical system structure is as follows: Figure 2 As shown, the aperture stop of a traditional Gaussian optical system is located in the middle of the system, enabling a large field of view. However, this results in some ineffective areas in the first and last lenses. In this invention, the entrance pupil is located at the first lens, ensuring that the aperture of the first lens matches the entrance pupil. By adjusting the distance between the last lens and the focal plane, the aperture of the largest optical element in the lens is controlled to meet the aperture requirements. This invention's transmissive optical system can achieve a field of view of 18° × 18° or more, achieving full coverage of the Earth's disk in geosynchronous orbit.

[0028] Radiation cooling directed towards deep space keeps the temperature of the optical system below 220K throughout the optical path. The long-term shaded side of the radiation-cooled system is located in the X-axis direction of the satellite, facing deep, cold space. Multiple cameras are integrated and mounted on the top of the satellite, aimed at the Earth for imaging. The electronics processor interacts with the target processing subsystem via fiber optic cable or 2711 cable. The camera focal planes are cooled using pulse tube refrigerators.

[0029] 2. Target Processing Subsystem

[0030] The target processing subsystem extracts the two-dimensional planar coordinates of targets from infrared images, generating the target's three-dimensional position and velocity. This invention employs an optimized allocation method, rationally assigning different targets to different satellites for data fusion, avoiding the waste of onboard resources caused by multiple satellites fusing the same target due to lack of allocation. The target processing subsystem includes a target detection module, an autonomous geometric calibration module, and a data fusion module, using a board-type architecture. Each module consists of multiple boards, and the number of boards can be configured according to the target processing capacity requirements. Each board integrates a high-performance processor and supporting software processing algorithms to achieve real-time target detection and fusion. The target processing subsystem transmits data to the camera subsystem via fiber optic cable or 2711 cable. It interacts with the mission planning subsystem via 2711 cable, SpaceWire bus, RS422 serial port, or other interfaces.

[0031] The target processing subsystem includes a point target detection module, an autonomous geometric calibration module, and a data fusion module. The target detection module extracts the two-dimensional trajectory of point targets in the infrared image through a target detection algorithm. The autonomous geometric calibration module determines the positions of typical feature points such as stars and ground features in the infrared image and provides geometric calibration coefficients in real time. The data fusion module fuses the two-dimensional planar position information of the two satellites into three-dimensional position and velocity information. At the same time, it uses a dynamic optimization fusion allocation algorithm based on the observation area to allocate the fusion calculation of multiple targets to different satellites for fusion.

[0032] 3. Task Planning Subsystem

[0033] The mission planning subsystem calculates the orbital positions and observation capabilities of other cooperating satellites based on the target's three-dimensional position, and plans observation missions for the other cooperating satellites.

[0034] The mission planning subsystem includes modules for target threat priority assessment, resource scheduling, and conflict resolution. The hardware utilizes high-performance DSPs and SOCs for computation, while the software models include orbit extrapolation models, target trajectory extrapolation models, visibility window calculation models, priority ranking models, scheduling optimization models, and conflict resolution models. The mission planning subsystem interacts with the inter-satellite network subsystem via interfaces such as SpaceWire bus and RS422 serial port. The target threat priority assessment module evaluates target priorities based on the 3D position and velocity information of point targets obtained through fusion calculations by the target processing subsystem. The resource scheduling module schedules other satellites and ground facilities with collaborative capabilities according to target priorities. When conflicts arise in the scheduling of other resources, the conflict resolution module is responsible for coordination.

[0035] 4. Inter-satellite network subsystem

[0036] The inter-satellite network subsystem is responsible for receiving two-dimensional angular trajectories provided by other satellites and providing them to the target processing subsystem, while also sending information such as collaborative planning generated by the mission planning subsystem to other satellites;

[0037] The inter-satellite network subsystem includes inter-satellite laser communication equipment, inter-satellite Ka phased array communication equipment, and inter-satellite network management equipment. The inter-satellite laser communication equipment boasts a high data rate and is used to communicate with other satellites with high data exchange needs. The inter-satellite Ka communication equipment is used to communicate with satellites with general data exchange needs. The inter-satellite network management equipment handles the conversion of communication protocols between different satellites, the operation and maintenance of the inter-satellite network, and data transmission routing. The inter-satellite laser communication equipment and the inter-satellite Ka phased array communication equipment are installed on the surface of the satellite, with the installation location selected based on the orbital position of the satellite requiring information exchange. The inter-satellite laser communication equipment uses a full-duplex system, with a laser communication rate of 0–4 Gbps and a range of no less than 70,000 kilometers. The laser communication equipment is installed on both sides of the satellite to network with other satellites possessing laser communication capabilities. The inter-satellite Ka phased array communication equipment has multiple transmit / receive capabilities, with the phased array antenna installed outside the satellite.

[0038] 5. Imaging Quality Assurance Subsystem

[0039] The imaging quality assurance subsystem includes an angular displacement measuring instrument. Due to the influence of external orbital heat flow, the satellite's star sensor and camera structural reference undergo thermal deformation. The angular displacement measuring instrument is integrated with the camera to measure on-orbit thermal deformation and camera line-of-sight jitter. The imaging quality assurance subsystem provides high-precision deformation measurement results for the satellite, and combined with onboard autonomous geometric calibration, provides high-precision geometric calibration coefficients for dual-satellite data fusion.

[0040] The laser emitted by the angular displacement measuring instrument is reflected by the reflective surface of the central reference component and returns to the angular displacement measuring instrument. By measuring the coordinate deviation of the zero position and the offset position of the reflected light, the angular displacement of the camera in the azimuth and elevation directions can be calculated respectively, and finally accurate thermal deformation data can be obtained.

[0041] 6. Sunshade Subsystem

[0042] The sunshade subsystem is located outside the camera and, in conjunction with the satellite's autonomous sunlight avoidance strategy, suppresses and isolates light incidence. The satellite platform provides the above subsystems with supporting capabilities such as energy, structure, and thermal control.

[0043] The sunshade subsystem mainly consists of a sun-shielding film and a lightweight, deployable frame. During launch, the sunshade is in a compressed state to meet the space requirements of the launch vehicle's fairing. After entering orbit, the sunshade is fully deployed. The sunshade is installed around the camera, and according to the satellite's autonomous sunlight avoidance strategy, the sun-blocking side of the sunshade must be aligned with the direction of sunlight incidence during installation.

[0044] The sunshade uses a lightweight, deployable frame as its main support, with a thin film installed on the outside of the frame. The sunshade subsystem is mounted outside the camera, with the light-blocking surface facing the direction of sunlight incident on the satellite. Through a sunlight avoidance strategy, the sunshade can consistently block sunlight. The sunshade's bevel angle is less than or equal to 15°, and its height in the compressed state does not exceed 1 meter. After the satellite enters orbit, the sunshade deploys in three dimensions in two stages: first, it deploys laterally using a passive drive, and then it deploys longitudinally using a sleeve deployment mechanism.

[0045] In summary, the above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0046] It will be apparent to those skilled in the art that the embodiments of the present invention are not limited to the details of the exemplary embodiments described above, and that the embodiments of the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the embodiments of the present invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the embodiments of the present invention is defined by the appended claims rather than the foregoing description. Therefore, it is intended that all variations falling within the meaning and scope of equivalents of the claims be encompassed within the embodiments of the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims. Furthermore, it is clear that the word "comprising" does not exclude other units or steps, and the singular does not exclude the plural. Multiple units, modules, or devices recited in the system, apparatus, or terminal claims may also be implemented by the same unit, module, or device through software or hardware. The terms "first," "second," etc., are used to indicate names and do not indicate any particular order.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of the present invention and are not intended to limit them. Although the embodiments of the present invention have been described in detail with reference to the above preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of the embodiments of the present invention should not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A wide-area infrared point target detection and tracking cooperative satellite system, characterized in that, The system includes: a camera subsystem, a target processing subsystem, a mission planning subsystem, an inter-satellite network subsystem, an imaging quality assurance subsystem, and a sunshade subsystem. The camera subsystem is used to image infrared point targets over a wide area, generating a wide-area surveillance image including targets with weak infrared radiation, and providing the image data to the target processing subsystem. The target processing subsystem extracts the two-dimensional planar coordinates of the targets from the infrared images, generates the three-dimensional position and velocity of the targets, and rationally assigns different targets to different satellites for data fusion. The mission planning subsystem calculates the orbital positions and observation capabilities of other cooperating satellites based on the three-dimensional position of the targets, and plans observation missions for other cooperating satellites. The inter-satellite network subsystem is responsible for receiving the two-dimensional angular trajectories provided by other satellites and... It provides data to the target processing subsystem and simultaneously transmits collaborative planning information generated by the mission planning subsystem to other satellites; the imaging quality assurance subsystem provides high-precision deformation measurement results of the satellite, and, combined with on-board autonomous geometric calibration, provides high-precision geometric calibration coefficients for dual-satellite data fusion; the sunshade subsystem is located outside the camera and, combined with the satellite's autonomous sunlight avoidance strategy, achieves suppression and isolation of light incidence; the target processing subsystem includes a target detection module, an autonomous geometric calibration module, and a data fusion module; the mission planning subsystem connects to the inter-satellite network subsystem for data interaction, including a target threat priority assessment module, a resource scheduling module, and a conflict resolution module; the inter-satellite network subsystem includes inter-satellite laser communication equipment, inter-satellite Ka phased array communication equipment, and inter-satellite network management equipment.

2. The wide-area infrared point-target detection and tracking constellation of satellites system of claim 1 wherein, The camera subsystem includes an infrared camera, an electronics processor, and a refrigerator. The infrared camera employs a large-aperture, deep-temperature, transmission-type optical system. Its optical structure consists of multiple Gaussian aspherical lenses, providing an arbitrary selectable detection field of view within the range of 0°×0° to 25°×25°. The camera's focal plane is composed of a large-area infrared detector array. The electronics processor performs radiometric correction on the infrared image, generates raw image data according to a specified data format, and transmits it to the target processing subsystem. The refrigerator is a pulse tube refrigerator, with its long-term shaded side located in the satellite's X-axis direction, facing deep space, providing radiative cooling to the large-area infrared detector array.

3. The wide-area infrared point-target detection and tracking constellation of satellites system of claim 1 wherein, The target detection module extracts the two-dimensional trajectory of point targets in the infrared image through a target detection algorithm. The autonomous geometric calibration module determines the position of typical feature points in the infrared image and provides geometric calibration coefficients in real time. The data fusion module fuses the two-dimensional planar position information of the two satellites into three-dimensional position and velocity information. At the same time, by adopting a dynamic optimization fusion allocation algorithm based on the observation area, the fusion calculation of multiple targets is allocated to different satellites for fusion.

4. The wide-area infrared point target detection and tracking cooperative satellite system as described in claim 1, characterized in that, The target threat priority assessment module evaluates the target priority based on the three-dimensional position and velocity information of the point target obtained by the target processing subsystem through fusion calculation; the resource scheduling module schedules other satellites and ground facilities with collaborative working capabilities according to the target priority; when conflicts occur in the scheduling of other resources, the conflict resolution module is responsible for coordination.

5. The wide-area infrared point target detection and tracking constellation of any of claims 1-4, wherein: The inter-satellite laser communication device is used to communicate with other satellites that have high data exchange requirements; the inter-satellite Ka communication device is used to communicate with satellites with general data requirements; the inter-satellite network management device is used to complete the conversion of communication protocols between different satellites, the operation and maintenance of the inter-satellite network, and data transmission routing.

6. The wide-area infrared point-target detection and tracking constellation of claim 1 wherein, The imaging quality assurance subsystem includes an angular displacement measuring instrument, which is integrated with the camera subsystem to measure on-orbit thermal deformation and camera line-of-sight jitter. Based on the optical lever method of optical autocollimation principle, the laser emitted by the angular displacement measuring instrument is reflected back after being reflected by the reflective surface of the central reference component. By measuring the coordinate deviation of the zero position and the offset position of the reflected light, the angular displacement of the camera in the azimuth and elevation directions can be solved respectively, and finally accurate thermal deformation data can be obtained.

7. The wide-area infrared point-target detection and tracking constellation of claim 1 wherein, The sunshade subsystem is installed outside the camera subsystem. According to the satellite's autonomous sunlight avoidance strategy, the sunshade's light-blocking side needs to be aligned with the direction of sunlight incidence during installation. Through the sunlight avoidance strategy, the sunshade can always block sunlight. The sunshade includes a light-blocking film and a lightweight deployable frame, which is in a compressed state during launch to meet the space requirements of the launch vehicle fairing. After being put into operation in orbit, the light shield is deployed, specifically by adopting a three-dimensional secondary deployment method. First, it is deployed laterally using a passive drive method, and then it is deployed longitudinally using a sleeve deployment mechanism.

Images