Satellite-borne cold calibration and orbit planning method for synthetic aperture microwave radiometer

Abstract

The application provides a cold space calibration attitude and orbit cooperative planning method for a spaceborne synthetic aperture microwave radiometer, comprising: adopting a spaceborne ASMR main backlobe receiving rate weighting mechanism and a satellite fixed attitude celestial sphere brightness temperature integration mechanism to numerically evaluate a single on-orbit time celestial sphere brightness temperature background in an expected calibration time window; adopting a variable time scale sliding window to traverse the expected calibration time window, determining a brightness temperature background comprehensive evaluation value in the calibration time window and sorting, and eliminating similar calibration time windows; using the screened calibration time window and the attitude maneuver sequence in the window to represent an individual in a swarm intelligence optimization method and evolving the individual code; according to a vector constraint mode of a field of view main axis facing the cold space for sweeping and an attitude motion mode, generating an initial population of the swarm intelligence optimization method; according to the initial population, a cold space calibration constraint and an optimization target, using a multi-objective swarm intelligence optimization method to optimize and determine a calibration orbit window and an attitude maneuver sequence in the window.

Description

Technical Field

[0001] This invention belongs to the field of spacecraft mission planning technology, and specifically relates to a collaborative planning method for cold-space calibration attitude and orbit of a spaceborne integrated aperture microwave radiometer. Background Technology

[0002] Microwave radiometers are passive microwave remote sensors and an effective means of measuring microwave radiation, playing a vital role in the field of remote sensing. However, the spatial resolution and aperture of traditional microwave radiometers are mutually constrained; higher resolution and larger aperture lead to increased system weight, size, cost, and technical complexity. To overcome the shortcomings of traditional microwave radiometers, researchers have incorporated aperture synthesis techniques from radio astronomy observations into the design of microwave radiometers, developing the Aperture Synthetic Microwave Radiometer (AMSR), which resolves the inherent contradiction between spatial resolution and antenna physical size in traditional microwave radiometers.

[0003] However, ASMR systems are complex and require high observational accuracy, necessitating periodic on-orbit calibration to correct instrument drift. The cold sky background, characterized by its non-polarized brightness temperature, stability, and even uniform brightness temperature in some regions, is the only stable natural temperature reference in orbit. Therefore, cold sky calibration (CSC) is an effective on-orbit calibration method. CSC involves rotating the satellite's attitude during on-orbit maneuvers at specific time intervals, allowing the onboard ASMR's main field of view to observe the flat cold sky background (the payload's main lobe points to the "sky," and the back lobe to the "Earth"). This acquires the lowest possible and most stable brightness temperature observation data, which is then used for ASMR radiometric calibration and performance verification to eliminate instrument errors and ensure the satellite's observational accuracy and long-term stability.

[0004] Typical microwave radiometer systems (such as those carried by SMOS, Aquarius, and SMAP satellites) also use attitude maneuvers to perform periodic observations of the cold-sky background in order to assess absolute calibration capabilities and further refine imaging mode information. However, existing research mainly focuses on the conventional attitude maneuvers of real-aperture radiometers, and there is still a lack of effective solutions for on-orbit CSC planning with complex multiple constraints and multiple objectives.

[0005] The goal of attitude maneuver planning is to find the optimal or suboptimal attitude maneuver path for a spacecraft, given mission requirements, performance metrics, and constraints on payload and sensor states. Infrared space observatories have used attitude maneuver strategies to avoid Earth's thermal radiation to ensure the accuracy of sensitive payload detection; the Cassini spacecraft was equipped with an attitude avoidance mechanism to protect its various sensors from sunlight. In this process, researchers have employed various methods, including zero-drift angle attitude planning, fast-exploration random trees, global maneuver search based on attitude spherical shells, heuristic allocation strategies, special potential functions, and Newton's method with projection operators, combined with different attitude parameterization forms such as unit quaternions, Euler angles, improved Rodriguez parameters, and Lie groups. With the increasing complexity of space missions, single metrics are no longer sufficient to meet practical needs, and the Constrained Multi-objective Optimization Problem (CMOP) is becoming increasingly prominent. Existing technologies include using particle swarm optimization (PSO) to achieve faster attitude maneuvers under no-pointing conditions, and differential evolution algorithms (DEE) to encode angular velocity and time for CMOP in attitude planning. However, in scenarios where satellite on-orbit resources are limited and frequent iterative updates are required, these methods are prone to problems such as scarce feasible solutions and excessive computational cost. To overcome the bottleneck of local optima, researchers have proposed constrained multi-objective optimization algorithms to adjust and improve the convergence performance of traditional multi-objective algorithms, but these remain largely theoretical, and their adaptability to real satellite platforms still needs further investigation.

[0006] Unlike traditional microwave radiometers, ASMRs are characterized by a wide main beam and highly irregular distribution of side lobes and back lobes. This means that even if the satellite meets the constraints of its power supply, thermal control, and star sensor subsystems, it may still be difficult to complete CSC (Complete Scale) within a specified time period due to brightness temperature exceeding limits. Even more challenging is that spaceborne ASMRs often need to maintain continuous observations under fully constrained conditions within a specified time period. The superposition of multiple stringent constraints and an infinite number of possible attitude maneuvers often results in extremely scarce feasible solutions. Therefore, it is urgent to screen and optimize attitude / orbit planning schemes within a short period of time and ensure that cold-space observations of the spaceborne ASMR's main field of view meet key indicators such as low brightness temperature and small brightness temperature fluctuations.

[0007] Meanwhile, spaceborne ASMR requires periodic (1-2 times per month) CSC (Continuous Course Scheduling) and adjustments to input parameters based on actual operating conditions, demanding high algorithm efficiency and on-orbit feasibility. Existing work has introduced non-dominated sorting genetic algorithms or combined them with the concept of dynamic iterative scaling invariant sets in attitude and trajectory optimization, hoping to obtain good initial solutions and sufficient search depth under multi-dimensional objectives and constraints. However, most algorithms still tend to solve CMOP (Continuous Course of Orientation) under a single objective or a few simple indicators, and are still unable to cope with the global path search requirements under the linkage of attitude maneuvering and space brightness and temperature background, which is somewhat different from real-world on-orbit application scenarios.

[0008] Based on this, a collaborative planning method for attitude and orbit of spaceborne ASMR cold space calibration is proposed. This method aims to combine the stringent requirements of CSC (Cold Space Detection and Control) on brightness and temperature backgrounds with the complex constraints of satellite attitude and orbit maneuvers, constructing a multi-objective, multi-constraint optimization model, and utilizing a dynamic constraint multi-objective algorithm to efficiently search for feasible solutions in orbit. This approach is expected to overcome the limitations of existing algorithms in large-scale searches and real-time adaptability, providing a complete, feasible, and reliable mission planning approach for spaceborne ASMR to conduct CSC in different time windows. This lays an important foundation for the development of my country's passive microwave remote sensing program and breakthroughs in multi-payload collaborative calibration technology. Summary of the Invention

[0009] During their long service life, spaceborne ASMRs require multiple calibration surveys (CSCs) to ensure high accuracy and stability in radiation detection. However, the calibration process involves multiple constraints, including satellite attitude dynamics, harmful celestial object light vectors, and solar panel power requirements, resulting in high planning complexity and few feasible solutions. Furthermore, the on-orbit background radiation significantly interferes with the brightness temperature of the antenna payload. A key challenge in achieving long-term, high-precision calibration is how to stably complete CSCs during specific orbital periods with lower brightness temperature background radiation, while ensuring minimal changes in brightness temperature integral. This invention aims to solve the following problem: during the expected satellite calibration mission, searching for on-orbit periods with calibration advantages and determining the sequence of attitude maneuvers the satellite must perform within these periods to meet calibration constraints.

[0010] The technical solution provided by this invention is as follows: Firstly, a collaborative planning method for attitude and orbit calibration of a spaceborne integrated aperture microwave radiometer in cold space includes: A numerical evaluation of the celestial brightness temperature background at a single on-orbit moment within the expected calibration time window is conducted by using a weighted mechanism of the main back lobe receiver rate of spaceborne ASMR and an integral mechanism of celestial brightness temperature under fixed satellite attitude. A variable time-scale sliding window is used to traverse the expected calibration time window, determine and sort the comprehensive evaluation values ​​of brightness temperature and background within the calibration time window, and the lower the comprehensive evaluation value of brightness temperature and background, the higher the ranking. Similar calibration time windows are removed. Individuals in the swarm intelligence optimization method are represented by the selected calibration time window and the attitude maneuver sequence within the window, and the individual encoding is evolved. The encoding content includes orbit label, calibration duration, initial attitude Euler angles, initial three-axis attitude angular velocity and three-axis angular acceleration sequence. Attitude and orbit cooperative planning is implemented by combining dynamic recursion. Based on the vector constraint mode and attitude motion mode of sweeping towards cold air along the principal axis of the field of view, an initial population for the swarm intelligence optimization method is generated. Based on the constraints and optimization objectives of the initial population and cold-air calibration, a multi-objective swarm intelligent optimization method is used to optimize and determine the calibration orbit window and the attitude maneuver sequence within the window.

[0011] Secondly, a spaceborne integrated aperture microwave radiometer cold-space calibration attitude and orbit collaborative planning device includes: One or more processors; Storage device for storing one or more programs. When the one or more programs are executed by the one or more processors, the one or more processors implement the above-described collaborative planning method for cold-space calibration attitude and orbit of a spaceborne synthetic aperture microwave radiometer.

[0012] Thirdly, a readable storage medium storing a computer program that, when executed by a processor, implements the aforementioned collaborative planning method for cold-space calibration attitude and orbit of a spaceborne synthetic aperture microwave radiometer.

[0013] Fourthly, a computer program product, comprising: a computer program (also referred to as code or instructions), which, when run, executes the aforementioned collaborative planning method for cold-space calibration attitude and orbit of a spaceborne integrated aperture microwave radiometer.

[0014] The attitude and orbit collaborative planning method for cold-space calibration of a spaceborne synthetic aperture microwave radiometer provided by the present invention has the following beneficial effects: (1) The present invention provides a cold-space calibration attitude and orbit co-planning method for a spaceborne integrated aperture microwave radiometer. This method constructs a space brightness-temperature background radiation model to achieve numerical feedback of the antenna payload brightness-temperature integral, thereby screening the orbit brightness-temperature background within the desired mission period and forming a preliminary orbit screening heuristic rule for CSC mission planning. This rule uses a sliding time window traversal method to comprehensively evaluate the space brightness-temperature background exposed by the satellite antenna within each time window of the desired mission period. This largely avoids missing potential optimal time periods and provides diverse orbit time period inputs for subsequent evolutionary algorithms, while significantly reducing the search space for attitude and orbit co-planning. The orbit screening strategy utilizes a sliding time window to reduce the dimensionality of orbit information, thereby reducing the amount of orbit data involved in subsequent optimization problems, while retaining the potential orbit data solution space, ensuring a certain degree of diversity while reducing the amount of data.

[0015] (2) The present invention provides a collaborative planning method for attitude and orbit of a spaceborne integrated aperture microwave radiometer for cold space calibration. For the selected set of preferred calibration time windows, the method plans the attitude maneuver trajectory during the calibration mission, forming a collaborative planning algorithm for attitude and orbit with a variable time scale. This algorithm is oriented towards swarm intelligence optimization, designs optimization quantities for individual optimizations, and incorporates key elements such as attitude parameters, orbit window parameters, and calibration duration into the collaborative optimization process, so that the solution space has a higher degree of freedom. Subsequent optimization iterations can cover both attitude and orbit dimensions, thereby realizing collaborative planning.

[0016] (3) The present invention provides a cold-space calibration attitude and orbit collaborative planning method for a spaceborne integrated aperture microwave radiometer, and formulates a heuristic initial solution conjecture strategy. This strategy considers the "whole satellite flipping" mode of the satellite during CSC and related pointing constraints, which effectively improves the quality of the initial population, accelerates convergence, and ensures the rapid positioning of feasible solutions.

[0017] (4) The present invention provides a collaborative planning method for cold air calibration attitude and orbit of a spaceborne integrated aperture microwave radiometer. It adopts a constrained multi-objective optimization swarm intelligence algorithm and combines it with a multi-code segment mutation strategy. Through intelligent optimization, it improves the adaptability of the planning algorithm in terms of global search and optimization depth. It can realize the rapid search and deep optimization of CSC feasible solutions. First, the feasible solution search is completed, and then the high-quality solution is optimized. Attached Figure Description

[0018] Figure 1 This is a flowchart illustrating the implementation of the spaceborne ASMR cold-space calibration attitude and orbit collaborative planning method provided by this invention. Figure 2 Is to take The orbital screening results; Figure 3 It is the coding method for attitude and trajectory collaborative planning; Figure 4 yes The initial pose set of the initial population; Figure 5 This is a schematic diagram of the vector angle relationship (taking the principal axis of the field of view as an example). Detailed Implementation

[0019] The features and advantages of the present invention will become clearer and more apparent from the following detailed description.

[0020] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments.

[0021] Utilizing the cold cosmic background, the ASMR antenna's main field of view is shifted from the Earth's surface to cold space through attitude maneuvers. During specific orbital periods with low space brightness-temperature background radiation, the brightness-temperature integral of the antenna payload is continuously maintained within an effective calibration threshold. Simultaneously, the brightness-temperature integral variation is kept small within the calibration time window to minimize the interference of on-orbit space background radiation on the ASMR antenna payload. The calibration task requires comprehensive consideration of multiple constraints, including satellite attitude dynamics, harmful celestial object light vectors, and solar panel power requirements. The mission planning is highly complex, with few feasible solutions, posing significant engineering challenges. Therefore, this invention constructs a space brightness-temperature background radiation prediction model. Supported by efficient and high-precision brightness-temperature integral calculations, it facilitates the planning and design of the CSC mission, rapidly searches for feasible calibration solutions, and deeply optimizes multi-dimensional calibration indicators to meet mission requirements and improve engineering feasibility.

[0022] To achieve the above objectives, this invention provides a collaborative planning method for cold-space calibration attitude and orbit of a spaceborne integrated aperture microwave radiometer, such as... Figure 1 As shown, it includes the following steps: Step 1: Design a heuristic brightness temperature background evaluation method. By traversing the expected calibration time window, the celestial brightness temperature background at a single on-orbit moment within the expected calibration time window is numerically evaluated based on the weighted mechanism of the main back lobe receiver rate of the onboard ASMR and the integral mechanism of celestial brightness temperature under fixed satellite attitude.

[0023] When performing antenna brightness temperature integration, the antenna pattern beam is converted to the J2000 reference inertial frame, and the brightness temperature integration calculation is performed. This invention considers the changes in the beam pointing of the onboard ASMR antenna pattern in inertial space (or celestial coordinate system) caused by satellite attitude changes, which in turn cause changes in the brightness temperature integration. To clarify the data state requirements for the calculations in this invention, the brightness temperature background radiation fitting function is denoted as a function of satellite attitude, beam pointing angle coordinates, and on-orbit position, with the meaning of the function remaining unchanged.

[0024] For the right ascension and declination A database of binary computational cold air brightness temperature radiation background fitting functions, and geographic latitude and longitude. Database of binary-variable calculations for fitting surface brightness temperature radiation background functions. Current satellite attitude rotation matrix is ​​known. Mounting matrix of spaceborne antennas The current beam pattern can be pointed through The process involves transforming from the antenna coordinate system to the reference inertial system for coordinate interpretation and matching. Therefore, the application of the binary brightness temperature background radiation fitting function from the fitting function database in this invention is summarized as follows: (1) in, Indicates right ascension and declination Binary calculation of the cold air brightness temperature radiation background fitting function; Indicates geographical latitude and longitude Binary calculation of the background function for surface brightness temperature radiation; This represents the rotation matrix from the antenna coordinate system to the J2000 inertial system; These represent the satellite's roll angle and pitch angle, respectively. r This represents the satellite's on-orbit position vector. Also note... For nominal orbits, orbit prediction is based on the on-orbit time. t k Therefore, the above formula is written as follows: (2) The domain of the angular coordinates of the celestial cold space region is denoted as The domain of angular coordinates for a region on the Earth's surface is The following introduces two evaluation mechanisms for brightness temperature background: A dual-region weighted evaluation mechanism for celestial brightness temperature background based on the main back lobe receiver rate of spaceborne ASMR: Using existing antenna patterns, the brightness temperature integral contribution rate of the main lobe and back lobe of the spaceborne ASMR is used to perform a weighted evaluation of the cold space region and the surface region on the celestial brightness temperature background, thus obtaining a numerical evaluation method for the celestial brightness temperature background at the current on-orbit time.

[0025] Assume the current on-orbit time t k The percentage of the main lobe's contribution to the overall antenna brightness temperature integral is: Then the dorsal lobe is Let the brightness temperature function of the Earth's surface region against the background of the satellite celestial sphere at that moment be... The brightness temperature function of the cold air region is , , For the numerical evaluation of the azimuth angle in the antenna coordinate system, the weighted evaluation equation is as follows: (3) in, ; This represents the integral over the visible area of ​​the Earth's surface in the celestial brightness temperature, and the corresponding... This represents the integral over the cold space region of the bright temperature zone of the celestial sphere.

[0026] A celestial brightness temperature background antenna brightness temperature integral evaluation mechanism based on fixed attitude of satellite flight system: The existing antenna pattern is fixed in attitude with the satellite's flight coordinate system (VVLH orbital coordinate system) according to the rule of "main lobe pointing to the sky and back lobe pointing to the ground". The integral of the antenna with respect to the celestial brightness temperature background under the current single attitude is calculated for a single moment to obtain the numerical evaluation method of the celestial brightness temperature background at the current moment.

[0027] Pick t k With the satellite in a fixed attitude in the VVLH coordinate system, the principal axis of the field of view of the onboard ASMR antenna coincides with the backward extension of the Z-axis of the VVLH coordinate system. This results in the following attitude rotation matrix from the satellite's body coordinate system to the VVLH coordinate system. : (4) in, This represents the attitude rotation angle from the satellite body coordinate system to the VVLH coordinate system.

[0028] The fixed posture is selected according to the rule of "main lobe pointing to the sky, dorsal lobe pointing to the ground", and the selection method is not unique.

[0029] Suppose that The relative pattern function of the antenna power pattern at the current moment in the celestial coordinate system is: Then we have: (5) in, ; This represents the integral over the visible area of ​​the Earth's surface in the celestial brightness temperature, and the corresponding... This represents the integral over the cold space region of the bright temperature zone of the celestial sphere.

[0030] Therefore, for a single on-orbit moment within the expected calibration orbit period... t k Numerical evaluation of the brightness temperature background of the space where the satellite is located is as follows: The lower the value, the smaller the overall brightness temperature background radiation, making this moment more beneficial for calibration. Since actual calibration requires long-term observation, the evaluation at a single moment cannot be used as a reference; therefore, a comprehensive evaluation across consecutive moments must be adopted.

[0031] Step 2: A variable time-scale sliding window is used to traverse the calibration time window, calculate the comprehensive evaluation value of brightness temperature and background within the calibration time window, generate fluctuation curves, and sort them. Similar calibration time windows are eliminated and superior calibration time windows are selected using a staged time difference judgment rule.

[0032] Based on the numerical brightness temperature background evaluation method in step 1, the sum of the numerical brightness temperature background evaluations for all moments within each traversal window during the sliding traversal process is calculated with a step size of 1 second, and this sum is used as the comprehensive spatiotemporal evaluation of the brightness temperature background for that window. For the initial moment... The calibration time window duration is The time window, and its brightness temperature background spatiotemporal comprehensive numerical evaluation method are as follows: (6) in, This represents the spatiotemporal comprehensive evaluation value of brightness temperature background; the form of a time window writing set. .

[0033] By applying the above sliding window traversal calculation, the fluctuation curve of brightness temperature spatiotemporal background quality within the specified calibration period is obtained.

[0034] The extracted calibration time windows are sorted by their spatiotemporal comprehensive evaluation values ​​of brightness temperature and background. The smaller the evaluation value, the lower the brightness temperature value in the spatiotemporal space of the window, and the higher the ranking. This makes it more valuable for further attitude motion dynamics planning within the window.

[0035] To further reduce the complexity of the subsequent planning search space, considering that adjacent sliding windows have similar numerical evaluation results for their backgrounds, multiple calibration time windows with significant time differences are extracted. However, it is also noted that while eliminating planning windows without significant time differences, it is necessary to consider retaining those with excellent spatiotemporal brightness and temperature backgrounds. Therefore, this invention proposes a staged time difference determination rule. First, for any two starting times as follows... , The calibration time window is defined by setting a time set with a step size of 1 second. , The overlap of time windows between any two calibration time windows is defined as... The calculation method is as follows: (7) Among them, operations This indicates the number of elements in a set. This will be used for time difference evaluation to further narrow down the candidate window, and the specific implementation is as follows: Let the total number of calibration time windows participating in the evaluation after sorting be... N The earlier the group number, the better the evaluation of the calibration time window within that group. n The rule for determining the calibration time windows with significant time differences in a dataset is that the window overlap is no greater than [value missing]. The calculation method is as follows: (8) in This is a scaling parameter for the calibration time window difference. The larger the value, the more relaxed the judgment of the overlap of time differences between the top-ranked calibration time windows.

[0036] For any , Determine whether the overlap of the calibration time windows meets the set rules. Then retain both , ;like Then compare , To retain a smaller calibration time window for numerical evaluation. Get as Figure 2 Track selection results.

[0037] Step 3: Encode individuals in the swarm intelligence optimization design evolution population. The encoding content includes orbital label, calibration duration, initial attitude Euler angles, initial three-axis attitude angular velocity and three-axis angular acceleration sequence, and attitude and orbital collaborative planning is realized by combining dynamic recursion.

[0038] Swarm optimization is a heuristic optimization method based on the collective behavior of organisms in nature. Its core idea is to find the optimal solution to a problem by simulating cooperation and competition among individuals. In swarm optimization, the population consists of multiple individuals, each representing a potential solution to the problem. Encoding transforms the solution into a computer-processable form, such as binary, real numbers, or permutations. Optimization variables are the parameters that need to be adjusted; their combinations constitute the solution space. Fitness measures the quality of a solution, usually calculated through an objective function; higher fitness indicates a better solution. Constraints are conditions that must be satisfied in the problem, such as equality or inequality restrictions. To handle constraints, a penalty function is usually introduced, converting the degree of constraint violation into a penalty term and incorporating it into the fitness function, thereby guiding individuals towards feasible solutions. Swarm optimization iteratively updates the individuals in the population, gradually approaching the global optimum.

[0039] In this invention, the optimized individual is a CSC scheme, including a calibration orbit window and an attitude maneuver sequence within the window. First, based on the attitude-orbit cooperative planning concept, the relevant codes for orbital elements are determined, and these codes are based on… labels of positive integers in the data set L express, This indicates that the initial screening track data set is sorted by number. L The calibration time window, written as: (9) As can be seen, through positive integer labels L It can complete the calibration window data set for the orbit. The retrieval and correspondence, among which This represents the start time of the specified benchmarking planning period within the specified time window.

[0040] The following analysis examines the encoding of attitude elements, considering attitude maneuver sequence planning based on a calibration window using attitude dynamics kinematics integrals. First, an attitude dynamics and kinematics model based on attitude quaternions is introduced within a reference inertial frame (J2000 frame used in this study): (10) in, Let represent the attitude quaternion in the reference inertial frame, which satisfies the normalization constraint. , Its scalar part, Its vector part; Indicates the satellite's three-axis attitude angular velocity. This represents the three-axis attitude angular acceleration of the satellite. Quaternions offer better stability when dealing with attitude motion dynamics. Therefore, this invention uses them here in the dynamic integral model of the optimization problem.

[0041] It is expressed as follows:

[0042] Additionally, let the rotation matrix from the satellite's body coordinate system to the J2000 reference inertial system be... There are conversion operations between rotation matrices and attitude quaternions: (11) And the transformation relationship of the attitude quaternion rotation matrix: First, construct the matrix. : (12) In the formula, , , , , , , , , Representing rotation matrices respectively The elements in.

[0043] Calculate matrix K eigenvalues Select the largest eigenvalue Calculate the eigenvector corresponding to the largest eigenvalue. This eigenvector is the desired attitude quaternion.

[0044] In this invention, the transformation from rotation matrix to attitude quaternion and the transformation from attitude quaternion to rotation matrix are respectively abbreviated as: (13) In the formula, A This represents the conversion function.

[0045] The following analysis examines the attitude description characteristics in the satellite's flight coordinate system. Based on the VVLH orbit coordinate system, the attitude Euler angles of the satellite body coordinate system relative to the VVLH orbit coordinate system are used. Perform attitude description: (14) in, These represent roll, pitch, and yaw angles, respectively. Euler angles describe the relative attitude of two coordinate systems by describing their rotation around the three axes in sequence. Roll, pitch, and yaw angles describe the rotation around the body coordinate system, respectively. axis, axis, Rotation of an axis can be written in the form of a rotation matrix: (15) It is important to note that Euler angles will produce different descriptions of the same pose depending on the rotation order. The rotation matrices corresponding to Euler angles in the XYZ rotation order are (representing the transformation from the body coordinate system to the orbit coordinate system): (16) Assume the VVLH orbital coordinate system is in the J2000 reference inertial frame. The unit orthogonal coordinate base is According to the definition of the VVLH orbital coordinate system Let the satellite's position vector and velocity vector be respectively... , It is expressed as follows: (17) Wherein, unit vector The calculations are as follows:

[0046] Notice: Pointing towards the Earth's center; It is the negative normal to the orbital plane (negative direction of angular momentum). Along the flight direction, from Sure.

[0047] Let the rotation matrix between the VVLH orbital coordinate system and the J2000 reference inertial frame be... It changes depending on the orbital position and is only related to the orbital position. The equivalent is as follows: (18) In summary, considering the above attitude description methods and their kinematic dynamics analysis, for encoding attitude information in an individual, this invention sets it as a dynamic integral recursive form, that is, given the initial attitude Euler angles under VVLH in the encoding sequence. Initial three-axis attitude angular velocity in the inertial frame And the set of attitude triaxial angular accelerations corresponding to all time series within the calibration window in the inertial frame. By referring to existing track element coding labels L and calibration duration coding By integrating the dynamic information from the attitude encoding over the initial attitude, the entire sequence of attitude paths within the calibration window can be obtained. The encoding method for attitude-orbit co-planning is as follows: Figure 3 As shown.

[0048] Based on the above individual coding design method, the decoding integration method for discrete sequences based on attitude and trajectory information is as follows: First, it is known The coded calibration track window information can be obtained. Next, based on the orbital calibration window and the orbital prediction sequence of the nominal orbit, the satellite position and velocity information and local latitude and longitude information within the corresponding on-orbit time are obtained, and then the calibration duration coding segment is used. This yields the valid attitude maneuver sequence within the given time window, and all subsequent performance calculations are based on this valid attitude maneuver sequence. The set of transformation relationships between the orbital coordinate system and the reference inertial frame within this calibration window is then calculated using formulas. Furthermore, it is known that... The transformation relationship between the satellite body coordinate system and the VVLH orbit coordinate system at the initial moment can be obtained using the formula. Furthermore, the initial attitude rotation matrix of the satellite in the J2000 inertial coordinate system is obtained by multiplying the rotation matrices. Based on the aforementioned formula (13), the satellite attitude quaternion in the current J2000 coordinate system is obtained. Furthermore, by integrating the attitude motion dynamics, all attitude angular motion sequences within this time window are obtained. and quaternion pose description sequences .

[0049] Step 4: Based on cold air sweep constraints, a heuristic initial population generation mechanism is formulated. By combining the principal axis of the field of view and vector constraints with attitude motion patterns, the individual quality is improved while ensuring population diversity.

[0050] Considering the requirements of the field-of-view sweeping mode facing cold air, a high-quality initial population is generated based on the vector constraint mode and attitude motion mode of the field-of-view sweeping mode facing cold air, aiming to maximize the quality of individuals within the initial population while preserving its randomness and diversity: First, for the initial screening of the orbital data set Randomly select track labels ; Next, initial VVLH attitude Euler angles are randomly generated based on the cold-space sweep mode of the satellite antenna's main line of sight during the full satellite flip, ensuring that the angle between the principal axis of the field of view and the -Z axis of the VVLH orbital coordinate system is within a certain range. Within. By adjusting This allows for a greater degree of flipping in the satellite's CSC mode. A larger satellite rollover occurs during CSC, and the more stable the path change during cold air sweep, the faster the optimization algorithm converges; smaller changes result in a larger satellite rollover. A smaller satellite rollover, and greater diversity in path changes during cold air sweeping (CSC), contribute to the global advantage of the convergence results. The initial pose set of the initial population is as follows Figure 4 As shown.

[0051] Step 5: Numericalize the constraints and optimization objectives of CSC. Constraints include attitude kinematics, brightness temperature integral, field of view taboo angle, and solar panel light vector angle; optimization objectives include calibration time, attitude kinematics, brightness temperature integral, and field of view angle optimization.

[0052] For the calibration track window The calibration orbit background is analyzed, taking any time point. Therefore, there are specific times. Satellite inertial frame attitude quaternion Euler angles in the satellite's VVLH orbital coordinate system Satellite three-axis attitude angular velocity Satellite three-axis attitude angular acceleration Let the unit vector of the principal axis of the field of view of the onboard ASMR antenna in the satellite body coordinate system point to... The solar panel's normal unit vector points to The unit vectors of the optical axes of the three star sensors point to the following directions respectively: For time Its absolute orientation in the J2000 coordinate system is calculated as follows: (19) in, The unit vector pointing to the principal axis of the field of view of the spaceborne ASMR antenna in the J2000 coordinate system; This indicates the direction of the unit vector normal to the solar panel in the J2000 coordinate system. This indicates the unit vector pointing of the optical axes of the three star sensors in the J2000 coordinate system.

[0053] set up At any given moment, the semi-cone angle of the visible area of ​​Earth relative to the satellite under the inertial celestial sphere is... Let the Earth's radius be... Atmospheric thickness is , The calculation is as follows: (20) set up The solar and lunar position vectors in the J2000 system, predicted based on orbital data, are as follows: Let any characteristic vector in the satellite's body coordinate system be... , Angle with the Earth's center at all times Solar vector angle Moon vector angle The calculations are as follows: (twenty one) The following analysis will focus on the relevant CSC task constraints.

[0054] Numericalization of eigenvector constraints: Let the unit vector of the principal axis of the field of view of the spaceborne ASMR antenna in the J2000 coordinate system point to The angles between the Earth's center, the Sun, and the Moon are respectively , , ; Solar panel normal unit vector direction The angle between it and the sun is ; The optical axis unit vector pointing of the three star sensors The angles between the Earth's center, the Sun, and the Moon are respectively , , ; , , ; , , ;See Figure 5 .

[0055] for The attitude taboo cone constraint that the Earth (including its atmosphere), Moon, and Sun must not appear within ±90° of the principal axis of the field of view at any given time is expressed as follows: (twenty two) Among them, operations Used to compare and determine the largest number within the parentheses.

[0056] for The attitude taboo cone constraint that the Earth (including the atmosphere), the Moon, and the Sun must not appear within the ±35° field of view of at least one star sensor on the satellite is expressed as follows: (twenty three) in, j This indicates the star sensor number.

[0057] for The attitude forced cone constraint, where the angle between the solar panel normal and the solar vector on the satellite is within 50° at any given time, is expressed as follows: (twenty four) Considering the calibration window for the above attitude angle constraints. The full time series is represented numerically as follows: For calibration window The attitude taboo cone constraint, which prohibits the appearance of the Earth (including its atmosphere), Moon, and Sun within a ±90° field of view along the principal axis of the field of view throughout the entire time sequence, is expressed as follows: (25) For calibration window The attitude taboo cone constraint, which requires that the Earth (including its atmosphere), the Moon, and the Sun must not appear within a ±35° field of view of at least one star sensor on the satellite throughout the entire time sequence, is expressed as follows: (26) For calibration window The attitude forced cone constraint for the entire time series, where the angle between the solar panel normal and the solar vector on the satellite is within 50°, is expressed as follows: (27) Therefore, we performed numerical calculations of the attitude taboo cone and forced cone constraints on the full time-series data of the calibration window, and preserved gradient information in the calculation of the constraints, which helps to effectively find feasible solutions during the optimization process.

[0058] Attitude motion dynamics constraint handling: for The attitude kinematic constraint that the three-axis angular velocity of the satellite at any given time is no greater than 0.12° / s is expressed as: (28) for The three-axis angular acceleration of the satellite maneuver at any given time shall not exceed 0.0006° / s². 2 The attitude dynamics constraints are expressed as: (29) For calibration window The attitude kinematic constraints for satellite maneuvers with a three-axis angular velocity not exceeding 0.12° / s throughout the entire time series are expressed as follows: (30) For calibration window Throughout the entire timeline, the three-axis angular acceleration of the satellite maneuver is no greater than 0.0006° / s². 2 The attitude dynamics constraints are expressed as: (31) Milky Way Angle Constraint: Let a unit coordinate vector on the Milky Way strip in the antenna coordinate system be... , G Let be the set of unit coordinate vectors for the Milky Way bands. Let z, x, and y be the orthogonal unit coordinate bases in the antenna coordinate system, with the z-axis pointing towards the principal axes of the field of view. The projection matrix of the zoy plane is... The projection matrix of the Zox plane is .

[0059] The constraint variables for the required antenna coordinate system with ±35° x and ±70° y directions and no Milky Way are expressed as follows: For any two vectors Angle operation is defined as The violation of the constraint angle in the x-direction pointed to by the antenna at a single moment is defined as follows: The violation of the constraint angle in the y-direction is defined as follows: .

[0060] The constraint numericalization method for a single moment is defined as follows:

[0061] Therefore, the constraint that there is no Milky Way in the x-direction ±35deg and y-direction ±70deg in the required antenna coordinate system is expressed as: (32) For calibration window Full timing, represented as: (33) Antenna brightness temperature integral constraint processing (taking spaceborne one-dimensional and two-dimensional ASMR synchronous cold space calibration as an example; when only one type of ASMR cold space calibration is performed, the constraint of the other type can be relaxed): Consider a two-dimensional ASMR power pattern. The one-dimensional ASMR power pattern is .

[0062] have Brightness temperature integral of two-dimensional ASMR over time: (34) Brightness temperature integral of one-dimensional ASMR: (35) for The constraint that the brightness-temperature integral of the two-dimensional ASMR antenna at any given time is no greater than 4K is expressed as follows: (36) for The constraint that the brightness temperature integral of a one-dimensional ASMR antenna at any given time is no greater than 8K is expressed as follows: (37) for The constraint that the root mean square error of the brightness-temperature integral of the two-dimensional ASMR antenna within a 100-second time window relative to the average value of that window should not exceed 0.04K is expressed as follows: (38) in,

[0063] for The constraint that the difference between the maximum and minimum brightness temperatures within a 600-second time window of the one-dimensional ASMR antenna brightness temperature integral is less than 0.1K is expressed as: (39) in:

[0064] For calibration window The constraint that the brightness-temperature integral of a spaceborne two-dimensional ASMR antenna is no greater than 4K across all timeframes is expressed as follows: (40) For calibration window The constraint that the brightness-temperature integral of a spaceborne one-dimensional ASMR antenna is no greater than 8K across all timeframes is expressed as follows: (41) For calibration window The "brightness temperature flatness constraint" for the full-time, spaceborne ASMR antenna brightness temperature integral within a 100-second time window, where the root mean square error relative to the average value of that window is no greater than 0.02K, is expressed as: (42) For calibration window The "brightness temperature fluctuation constraint" that ensures the difference between the maximum and minimum brightness temperatures within a 600-second time window of the brightness temperature integral of a spaceborne ASMR antenna is less than 0.1K is expressed as follows: (43) Step 6: Using a multi-objective optimization algorithm, the multi-code segment mutation method of this invention is employed to solve multi-constraint, multi-objective optimization problems, improving planning efficiency and solution quality. This invention sets CSC attitude-orbit collaborative planning as an MOP (Multi-Objective Optimization Problem) and proposes the following combinations of multi-objective optimization objective functions for the full time series of the calibration time window, wherein the dimension of the optimization objective vector must not be less than 2: (45) in and These are constraints; Optimizing hard constraints includes: (46) Given that the hard constraints are satisfied, the soft constraints for further optimization include: (47) This invention also provides a spaceborne integrated aperture microwave radiometer cold-space calibration attitude and orbit collaborative planning device, comprising: One or more processors; Storage device for storing one or more programs. When the one or more programs are executed by the one or more processors, the one or more processors implement the above-described collaborative planning method for cold-space calibration attitude and orbit of a spaceborne synthetic aperture microwave radiometer.

[0065] The present invention also provides a readable storage medium storing a computer program that, when executed by a processor, implements the above-described collaborative planning method for cold-space calibration attitude and orbit of a spaceborne synthetic aperture microwave radiometer.

[0066] The readable storage media include, but are not limited to, USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, optical disks, and other media capable of storing program code.

[0067] The present invention also provides a computer program product, which includes a computer program (also referred to as code or instructions) that, when the computer program is run, executes the above-described collaborative planning method for cold-space calibration attitude and orbit of a spaceborne integrated aperture microwave radiometer.

[0068] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. The computer program product includes one or more computer instructions. When the computer instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transferred from one computer-readable storage medium to another.

[0069] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0070] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

[0071] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A collaborative planning method for attitude and orbit calibration of a spaceborne integrated aperture microwave radiometer in cold space, characterized in that, include: A numerical evaluation of the celestial brightness temperature background at a single on-orbit moment within the expected calibration time window is conducted by using a weighted mechanism of the main back lobe receiver rate of spaceborne ASMR and an integral mechanism of celestial brightness temperature under fixed satellite attitude. A variable time-scale sliding window is used to traverse the expected calibration time window, determine and sort the comprehensive evaluation values ​​of brightness temperature and background within the calibration time window, and the lower the comprehensive evaluation value of brightness temperature and background, the higher the ranking. Similar calibration time windows are removed. Individuals in the swarm intelligence optimization method are represented by the selected calibration time window and the attitude maneuver sequence within the window, and the individual encoding is evolved. The encoding content includes orbit label, calibration duration, initial attitude Euler angles, initial three-axis attitude angular velocity and three-axis angular acceleration sequence. Attitude and orbit cooperative planning is implemented by combining dynamic recursion. Based on the vector constraint mode and attitude motion mode of sweeping towards cold air along the principal axis of the field of view, an initial population for the swarm intelligence optimization method is generated. Based on the constraints and optimization objectives of the initial population and cold-air calibration, a multi-objective swarm intelligent optimization method is used to optimize and determine the calibration orbit window and the attitude maneuver sequence within the window.

2. The method for collaborative planning of attitude and orbit for cold-space calibration of a spaceborne integrated aperture microwave radiometer according to claim 1, characterized in that, The steps for numerically evaluating the celestial brightness temperature background at a single on-orbit moment within the expected calibration time window, using a satellite-borne ASMR main back lobe receiver rate weighting mechanism, include: Using the existing antenna pattern, the brightness temperature integral contribution rate of the main lobe and back lobe of the spaceborne ASMR is used to perform a weighted evaluation of the cold air region and the ground region on the celestial brightness temperature background, so as to obtain the numerical evaluation of the celestial brightness temperature background at the current on-orbit time. Assume the current on-orbit time t k The percentage of the main lobe's contribution to the overall antenna brightness temperature integral is: Then the dorsal lobe is Let the brightness temperature function of the Earth's surface region against the background of the satellite celestial sphere at that moment be... The brightness temperature function of the cold air region is , , For the numerical evaluation of azimuth angle in antenna coordinate system, the numerical evaluation of celestial brightness temperature background is also required. for: in, Represents a single on-orbit moment t k Numerical evaluation of the brightness temperature background of the space in which the satellite is located; , This represents the integral over the visible area of ​​the Earth's surface in the celestial brightness temperature. This represents the integral over the cold space region of the bright temperature zone of the celestial sphere; This represents the domain of angular coordinates for the cold space region of the celestial sphere. Represents the domain of angular coordinates for a region on the Earth's surface; Indicates right ascension and declination Binary calculation of the cold air brightness temperature radiation background fitting function; Indicates geographical latitude and longitude Binary calculation of the background function for surface brightness temperature radiation; This represents the rotation matrix from the antenna coordinate system to the J2000 inertial system; This indicates the latitude and longitude of the satellite's nadir point, which is provided by orbital prediction data; These represent the satellite's roll angle and pitch angle, respectively. r This represents the satellite's position vector in orbit.

3. The spaceborne integrated aperture microwave radiometer cold-space calibration attitude and orbit collaborative planning method according to claim 2, characterized in that, The steps for numerically evaluating the celestial brightness temperature background at a single on-orbit moment within the expected calibration time window, using a celestial brightness temperature integration mechanism under a fixed satellite attitude, include: The antenna pattern is fixed in attitude with the satellite's flight coordinate system according to the rule of "main lobe pointing to the sky, back lobe pointing to the ground". t k With the satellite in a fixed attitude in the VVLH coordinate system, the principal axis of the field of view of the onboard ASMR antenna coincides with the backward extension of the Z-axis of the VVLH coordinate system. This results in the following attitude rotation matrix from the satellite's body coordinate system to the VVLH coordinate system. : in, This represents the attitude rotation angle from the satellite body coordinate system to the VVLH coordinate system; Suppose that The relative pattern function of the antenna power pattern at the current moment in the celestial coordinate system is: Numerical evaluation of celestial brightness temperature background for: 。 4. The spaceborne integrated aperture microwave radiometer cold-space calibration attitude and orbit collaborative planning method according to claim 3, characterized in that, The step of using a variable time-scale sliding window to traverse the expected calibration time window and determine the comprehensive evaluation value of brightness temperature and background within the calibration time window includes: To set step size The sum of the numerical evaluations of brightness temperature and background at all times within each traversal window during the sliding traversal process is determined as the comprehensive spatiotemporal evaluation of brightness temperature and background for that window; for the initial time being... The upper and lower limits of calibration time are respectively ~ The time window, and its brightness temperature background spatiotemporal comprehensive numerical evaluation method are as follows: in, This represents the spatiotemporal comprehensive evaluation value of brightness temperature background; the form of a time window writing set. .

5. The spaceborne integrated aperture microwave radiometer cold-space calibration attitude and orbit collaborative planning method according to claim 4, characterized in that, After the step of using a variable time-scale sliding window to traverse the expected calibration time window and determine the comprehensive evaluation value of brightness temperature and background within the calibration time window, the method further includes: eliminating similar calibration time windows through a staged time difference judgment rule. The specific implementation method is as follows: For any two initial times, respectively , The calibration time window is defined by setting a time set with a step size of 1 second. , The overlap of time windows between any two calibration time windows is defined as... The calculation method is as follows: Among them, operations This indicates the calculation of the number of elements in the set; This will be used for time difference evaluation to further narrow down the candidate window, and the specific implementation is as follows: Let the total number of calibration time windows participating in the evaluation after sorting be... N The earlier the group number, the better the evaluation of the calibration time window within that group. n The rule for determining the calibration time windows with significant time differences in a dataset is that the window overlap is no greater than [value missing]. The calculation method is as follows: in This is a scaling parameter for the difference in calibration time windows. The larger the value, the more relaxed the judgment of the overlap of time differences between the top-ranked calibration time windows. For any , Determine whether the overlap of the calibration time windows meets the set rules. Then retain both , ;like Then compare , The calibration time window for numerical evaluation is relatively small.

6. The spaceborne integrated aperture microwave radiometer cold-space calibration attitude and orbit collaborative planning method according to claim 5, characterized in that, The step of generating the initial population for the swarm intelligence optimization method based on the vector constraint pattern and attitude motion pattern of sweeping towards cold air according to the principal axis of the field of view includes: For orbital data sets Randomly select track labels ; The initial VVLH attitude Euler angles are randomly generated based on the cold air sweep mode of the satellite antenna main line of view during the whole-satellite flip, so that the angle between the main axis of the field of view and the VVLH orbital coordinate system -Z axis is within the set angle range.

7. The spaceborne integrated aperture microwave radiometer cold-space calibration attitude and orbit collaborative planning method according to claim 6, characterized in that, In the step of optimizing and determining the calibration orbit window and the attitude maneuver sequence within the window using a multi-objective swarm intelligent optimization method based on the initial population, cold-air calibration constraints, and optimization objectives, the constraints of cold-air calibration include: For calibration window The attitude taboo cone constraint, which prohibits the appearance of the Earth, Moon, and Sun within a ±90° field of view along the principal axis of the field of view throughout the entire time sequence, is expressed as follows: For calibration window Throughout the entire time sequence, at least one star sensor on the satellite must not exhibit attitude taboo cone constraints for the Earth, Moon, or Sun within its ±35° field of view, as expressed as: For calibration window Full-time attitude forced cone constraint, where the angle between the solar panel normal and the solar vector on the satellite is within 50°, is expressed as: For calibration window The attitude kinematic constraint that the three-axis angular velocities of the satellite maneuver do not exceed 0.12° / s throughout the entire time series is expressed as: For calibration window Throughout the entire timeline, the three-axis angular acceleration of the satellite maneuver is no greater than 0.0006° / s². 2 The attitude dynamics constraints are expressed as: For calibration window With full timing, and no galactic constraints in the antenna coordinate system within ±35° of the x-direction and ±70° of the y-direction, it can be represented as: For calibration window The full-time constraint that the brightness-temperature integral of a spaceborne two-dimensional ASMR antenna is no greater than 4K is expressed as: For calibration window The full-time constraint that the brightness-temperature integral of a spaceborne one-dimensional ASMR antenna is no greater than 8K is expressed as: For calibration window The "brightness temperature flatness constraint," which specifies that the root mean square error of the brightness temperature integral relative to the average value within a 100-second time window of the spaceborne ASMR antenna is no greater than 0.02K, is expressed as: For calibration window The "brightness temperature fluctuation constraint," which specifies a difference of less than 0.1K between the maximum and minimum brightness temperatures within a 600-second time window of the brightness temperature integral of a spaceborne ASMR antenna throughout the entire time series, is expressed as follows: 。 8. A spaceborne integrated aperture microwave radiometer cold-space calibration attitude and orbit collaborative planning device, characterized in that, include: One or more processors; Storage device for storing one or more programs. When the one or more programs are executed by the one or more processors, the one or more processors implement the cold-space calibration attitude and orbit collaborative planning method for spaceborne synthetic aperture microwave radiometers as described in any one of claims 1 to 7.

9. A readable storage medium, characterized in that, It stores a computer program that, when executed by a processor, implements the cold-space calibration attitude and orbit collaborative planning method for a spaceborne synthetic aperture microwave radiometer as described in any one of claims 1 to 7.

10. A computer program product, characterized in that, The computer program product includes: a computer program that, when the computer program is run, executes the cold-space calibration attitude and orbit collaborative planning method for a spaceborne integrated aperture microwave radiometer as described in any one of claims 1 to 7.

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