Simulation method for illumination condition of spacecraft solar panel

Abstract

The invention discloses a method for simulating the illumination condition of a spacecraft solar panel, and the method comprises the steps: generating a point cloud file based on a three-dimensional model of a spacecraft body, building a cell array coordinate grid according to the distribution of cells of the solar panel, and then projecting each point in the point cloud file to a solar panel plane in the direction of a sun vector, and determining the distribution condition of the points in the point cloud file in the cell array coordinate grid, and finally determining the shadow area of the cell array coordinate grid according to the distribution condition to obtain the illumination condition of the solar panel. The simulation method can quickly and accurately calculate the illumination shielding condition of the solar panel, and provides key support for optimization design and operation control of a spacecraft energy system.

Description

Technical Field

[0001] The invention relates to the technical field of spacecraft simulation, and in particular to a method for simulating the illumination condition of a solar sail panel of a spacecraft. Background Art

[0002] As satellite functions continue to expand, satellite energy demand is growing. As the main source of satellite energy input, the distribution of shadows formed by solar panels under sunlight is directly related to the overall energy acquisition efficiency of satellites. At the same time, with the increasing frequency of low-Earth orbit space development activities, the satellite manufacturing industry is ushering in a wave of mass production. This trend puts forward requirements for satellite manufacturing processes to achieve low cost, high efficiency and high reliability. The implementation and verification of these optimization measures are inseparable from efficient and accurate satellite simulation technology.

[0003] In the process of satellite development, especially in the design and simulation link, traditional methods have many limitations, which seriously restrict the efficiency and reliability of satellite development. In the current satellite energy simulation system, there is a common problem that the processing of solar sail panel lighting conditions is not fine and accurate enough. Traditional satellite energy simulation generally only considers the satellite orbit lighting conditions and the angle between the battery array normal and the sun. It is assumed that the solar sail panel is not affected by the satellite body shielding during the entire operation cycle. This assumption ignores the complex shielding caused by various factors such as the attitude adjustment and orbital position change of the satellite in the actual orbit operation. In some simulation systems and methods, although the possibility of shielding is taken into account, it only adopts a highly simplified processing method, that is, the satellite body is simplified into a regular cube, and the solar light shielding under a certain instantaneous state is calculated based on this simplified model. This simplified processing method has significant defects. First, simplifying the satellite body into a cube ignores the complex shape design of the satellite, including various protruding components, antennas, sensors, etc. on it, which may cause actual shielding to the solar sail panel. Secondly, only considering the shielding situation under a certain state cannot fully reflect the changes in lighting conditions of the satellite during continuous operation. Due to these simplifications, existing satellite energy simulation systems often cannot accurately reflect the actual illumination conditions of solar panels in actual operation, and cannot perform continuous energy simulation of satellites at all times, which leads to a large deviation between the simulation results and the actual situation. Inaccurate simulation results will not only affect the accurate prediction of satellite energy input, but may also mislead the satellite's energy management strategy, thus posing a potential threat to the satellite's energy security. Summary of the invention

[0004] In view of some or all of the problems in the prior art, the first aspect of the present invention provides a method for simulating the illumination condition of a solar panel of a spacecraft, comprising:

[0005] Generate a point cloud file based on the three-dimensional model of the spacecraft's body, and establish a battery array coordinate grid according to the distribution of the solar cells on the solar panels;

[0006] Project each point in the point cloud file onto the solar panel plane in the direction of the solar vector;

[0007] Determine the distribution of the points in the point cloud file in the battery array coordinate grid; and

[0008] According to the distribution, determine the shaded area of the battery array coordinate grid to obtain the illumination condition of the solar panel.

[0009] Furthermore, the density of the point cloud file is determined according to the size of the solar cells on the solar panel.

[0010] Furthermore, projecting each point in the point cloud file onto the solar panel plane in the direction of the solar vector includes:

[0011] Convert the inertial system solar vector S i to the body system to obtain S b ; and

[0012] Rotate the Z-axis of the body system to the direction of S b direction.

[0013] Furthermore, determining the distribution of the points in the point cloud file in the battery array coordinate grid includes:

[0014] Rectify the projection of the battery array coordinate grid on the XY plane of the body system into a rectangle; and

[0015] Judge whether the coordinates of each point in the point cloud file fall within the coordinate ranges at both ends of the X-axis and Y-axis of the rectangle.

[0016] Furthermore, determining the distribution of the points in the point cloud file in the battery array coordinate grid also includes:

[0017] If there is a point on a certain solar cell, judge whether the solar cell is completely blocked.

[0018] Furthermore, determining the distribution of the points in the point cloud file in the battery array coordinate grid also includes:

[0019] Divide each solar cell that is not completely blocked into an N*N grid;

[0020] Statistically analyze the proportion of the grids with points in each solar cell; and

[0021] Summarize the proportion of the grid with points in each solar cell, and combine the distribution of all the shaded solar cells to obtain the distribution of the points in the point cloud file in the battery array coordinate grid.

[0022] Further, using the Monte Carlo method, each partially shaded solar cell is divided into an N*N grid.

[0023] Further, the value of N is 10.

[0024] Further, the simulation method further includes:

[0025] Determine the time periods when the spacecraft enters the earth's shadow and the moon's shadow. Based on the distribution of the point cloud file in the battery array coordinate grid during the non-entry time periods of the earth's shadow and the moon's shadow, determine the illumination conditions of the solar panels.

[0026] Further, the simulation method is implemented through a GPU.

[0027] Based on the simulation method as described above, a second aspect of the present invention provides a method for calculating the power generation current of a spacecraft solar panel, including:

[0028] According to the simulation method as described above, determine the shading conditions of the battery array of the solar panel; and

[0029] Based on the shading conditions, the angle between the solar panel and the solar vector, and the power generation efficiency of the battery, calculate the power generation current of the spacecraft solar panel.

[0030] A simulation method for the illumination conditions of a spacecraft solar panel provided by the present invention, with the aid of digital simulation technology and combined with a high-precision satellite structure model, can calculate the shadow distribution of the solar panel of the satellite in various situations in real time, thereby helping to obtain comprehensive and accurate satellite energy input data and improving the efficiency and reliability of the energy system. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] To further clarify the above and other advantages and features of the embodiments of the present invention, more specific descriptions of the embodiments of the present invention will be presented with reference to the drawings. It can be understood that these drawings only depict typical embodiments of the present invention and will not be considered as limiting its scope. In the drawings, for clarity, the same or corresponding components will be denoted by the same or similar reference numerals.

[0032] Figure 1 A flowchart showing a simulation method for the illumination conditions of a spacecraft solar panel according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] In the following description, the present invention is described with reference to various embodiments. However, those skilled in the art will recognize that the embodiments can be implemented without one or more specific details or in conjunction with other alternative and / or additional methods or components. In other instances, well-known structures or operations are not shown or described in detail to avoid obscuring the inventive aspects of the present invention. Similarly, for purposes of explanation, specific numbers and configurations are set forth in order to provide a thorough understanding of the embodiments of the present invention. However, the present invention is not limited to these specific details. In addition, it should be understood that the embodiments shown in the drawings are illustrative representations and are not necessarily drawn to scale.

[0034] In this specification, the reference to "an embodiment" or "the embodiment" means that the specific features, structures, or characteristics described in connection with the embodiment are included in at least one embodiment of the present invention. The phrase "in an embodiment" that appears throughout this specification does not necessarily refer to the same embodiment.

[0035] It should be noted that the embodiments of the present invention describe the method steps in a specific order. However, this is only for the purpose of illustrating the specific embodiment and does not limit the order of the steps. On the contrary, in different embodiments of the present invention, the order of the steps can be adjusted according to actual requirements.

[0036] In the design of a spacecraft power system, energy balance analysis and calculation are crucial tasks. The power generation information of the solar panels at each moment mainly depends on the angle between sunlight and the normal of the solar panels, the power generation efficiency of the solar panels, the light intensity, and the occlusion area, etc. Especially for a combined spacecraft, due to the complex occlusion relationships between the spacecraft body and the solar panels and between the solar panels themselves, it becomes particularly difficult to accurately calculate the occlusion area of the solar panels. To accurately calculate the sunlight occlusion of the solar panels of a combined spacecraft and improve the efficiency and reliability of the energy system, the present invention provides a simulation method for the sunlight illumination of spacecraft solar panels. Based on digital simulation technology and combined with a high-precision satellite structure model, it can calculate the shadow distribution of the solar panels of the satellite in various situations in real time. Specifically, the simulation method is implemented based on the method of calculating the orthographic projection of three-dimensional objects in the field of computer graphics. Methods for calculating the orthographic projection of three-dimensional objects in the field of computer graphics, such as the matrix transformation method combined with homogeneous coordinates, the ray tracing method, etc., can accurately calculate the projection of irregular objects, but the calculation amount is large. Based on this, CUDA calculation can be further utilized to improve the calculation efficiency of coordinate transformation and ray casting, enabling the real-time calculation of the sunlight occlusion of the solar panels.

[0037] The technical solution of the present invention will be further described below with reference to the accompanying drawings of the embodiments.

[0038] Figure 1Schematic flowchart of a simulation method for the illumination condition of a spacecraft solar panel according to an embodiment of the present invention. As Figure 1 shown, a simulation method for the illumination condition of a spacecraft solar panel includes:

[0039] First, in step 101, model preprocessing. The three-dimensional model of the spacecraft includes two parts: the main body and the solar panel. The main body part includes the main structure and equipment of the spacecraft, and the solar panel part is used to install the solar array. In an embodiment of the present invention, the main body model is converted into a point cloud file. In subsequent shadow calculations, each point in the spacecraft main body point cloud model is projected onto the panel plane in the direction of the solar vector, and whether the point falls on the solar array is used as a criterion for whether there is shadow occlusion. Based on this, in an embodiment of the present invention, it is necessary to adjust the density of the point cloud file according to the size of the solar cells on the solar array to ensure that the misjudgment that the solar cells have no shadow occlusion will not occur due to too sparse points. However, in order to avoid increasing the amount of calculation and affecting the calculation efficiency, the density of the point cloud file cannot be too high. In an embodiment of the present invention, before generating the point file, unnecessary model components can also be deleted to reduce the amount of calculation in subsequent program processing. In addition, for the solar panel part, it is necessary to obtain information such as the coordinates of the two rotation axes of the panel, the installation position of the panel, the size of the solar cells in the panel array, and the positions of each solar cell, and establish a solar array coordinate grid according to the actual distribution of the solar cells on the solar panel. The solar array coordinate grid is used to represent the positions and sizes of each solar cell on the panel, providing a basis for subsequent occlusion judgment;

[0040] Next, in step 102, parameter setting. Before performing the simulation operation, it is also necessary to input information such as the inertial system solar vector, the spacecraft attitude matrix, and the rotation angles of the A and B axes of the panel in each frame, so as to determine the relative position relationship between the sun, the spacecraft main body, and the solar panel, in order to better simulate the illumination condition. In an embodiment of the present invention, according to the attitude information of the spacecraft solar panel, the solar panel model rotates according to the two-axis rotation angles. First, obtain the coordinates Ax a 、Ax b of the two rotation axes A and B, and their corresponding rotation angles θ a 、θ b , from which the rotation matrices R a 、R b corresponding to the two rotations can be obtained respectively. Since the rotation axis A of the solar panel is fixedly connected to the spacecraft main body, and the rotation axis B is fixedly connected to the solar panel, the rotation order has no influence on the result. However, because the coordinate Ax b of the B axis fixedly connected to the solar panel will change with the rotation of the A axis, the solar panel model is first rotated around the B axis, and then rotated around the A axis. The solar panel coordinates P1 obtained after the two rotations are:

[0041] P1 = R a ·R b ·P0,

[0042] where P0 is the initial coordinate of the solar panel;

[0043] Next, in step 103, simulate the sunlight projection. Project each point in the point cloud file onto the solar panel plane in the direction of the solar vector. In an embodiment of the present invention, an orthogonal projection matrix is used to calculate the projection of sunlight on the spacecraft body. However, since the plane equation of the solar panel is uncertain, the calculation of the orthogonal projection matrix is complex, and the calculation of determining whether the projection falls on the solar cell is large. Therefore, in another embodiment of the present invention, a rotation method is adopted to calculate the sunlight projection. Specifically, first, the inertial system solar vector S i is transformed to the local system to obtain S b , and then the local system Z-axis where the spacecraft body and the solar panel are located is rotated to the direction of S b . In this way, the sunlight projections of the spacecraft body and the solar panel on the XY plane are exactly their XY coordinates. Furthermore, it is only necessary to determine whether there is a projection of a point in the spacecraft body point cloud within the battery cell grid on the XY plane to obtain the sunlight occlusion situation of each battery cell;

[0044] Next, in step 104, determine the point distribution. Determine the distribution of the points in the point cloud file in the battery array coordinate grid. The projection of the solar panel battery cell grid on the XY plane obtained by rotation in step 103 will be an arbitrary parallelogram grid. Judging whether a point falls within a parallelogram is relatively complex. Based on this, in an embodiment of the present invention, certain preprocessing is first performed on the data, including: first, performing a translation transformation on the whole so that the coordinate origin of the battery array coordinate grid is located at the origin of the XY plane, then performing a rotation transformation on the whole so that the XY axes of the battery array coordinate grid are parallel to the XY axes of the XY plane, and finally, according to the shape of the battery array coordinate grid, calculating a shear transformation matrix and applying a shear transformation to the whole to make the parallelogram projection of the battery grid regularize into a rectangle. Based on this, the following method can be used to judge whether a certain point in the spacecraft point cloud is located on a certain battery block:

[0045] x0 ≤ p x ≤ x1,

[0046] y0 ≤ p y ≤ y1,

[0047] where (p x , p y ) are the coordinates of the point in the two-dimensional spacecraft body point cloud on the XY plane; x0 and x1 are the coordinates at both ends of the X-axis of the battery grid, and y0 and y1 are the coordinates at both ends of the Y-axis of the grid; and

[0048] Finally, in step 105, the illumination condition is determined. According to the distribution of the points, the shadow area of the battery array coordinate grid is determined to obtain the illumination condition of the solar sail panel. In one embodiment of the present invention, a battery block bucket is first constructed, and the points in the point cloud file of the spacecraft body are traversed through an idea similar to bucket sorting, and mapped to the battery block bucket. If there are points in the bucket, it means that the battery cell is in the shadow, and if there are no points in the bucket, it means that the battery cell is not blocked. In one embodiment of the present invention, in order to accurately calculate the occlusion condition, it is also necessary to determine whether the battery cell is completely blocked or partially blocked according to the distribution of the body point cloud in the battery array coordinate grid. For partially blocked batteries, the Monte Carlo method is further used to divide the battery cell into N*N grids. The shadow area ratio of the battery cell can be obtained by counting how many points are in the grid, where the value of N can be 10, for example. Finally, all the results are summarized to obtain the occlusion condition of the battery array coordinate grid.

[0049] Since the solar panels are completely blocked during the time period when the spacecraft enters the earth's shadow or the moon's shadow, in order to reduce the amount of calculation, in one embodiment of the present invention, before using the simulation method as described above to determine the illumination conditions of the solar panels, the time period when the spacecraft enters the earth's shadow or the moon's shadow is calculated based on the spacecraft's orbital information and the position information of the earth and the moon, and then the illumination conditions of the solar panels are determined based on the distribution of the point cloud file in the battery array coordinate grid only during the time period when the spacecraft does not enter the earth's shadow or the moon's shadow.

[0050] In addition, in the real-time simulation of energy systems, it is often necessary to quickly output the light shielding of solar panels, so in one embodiment of the present invention, GPU parallel computing is mainly used to accelerate the entire calculation process. In the simulation method described above, operations such as model translation, rotation, and shear transformation are all suitable for parallel computing, and the transformation results of different points will not affect other points. Based on this, in one embodiment of the present invention, a CUDA program is further written to quickly obtain results using a GPU.

[0051] At this point, the solar panels' light shielding can be calculated quickly and accurately, providing key support for the optimized design and operation control of the spacecraft's energy system. Specifically, after simulating the shielding of each battery in the battery array, the current generated by the battery array at this moment can be calculated by combining the angle between the solar panel and the sun vector and the power generation efficiency parameters of the solar panels.

[0052] The present invention provides a method for simulating the illumination condition of a spacecraft solar panel. By means of digital simulation technology and in combination with a high-precision structural model of a satellite, the shadow distribution of the satellite's solar panels under various conditions can be calculated in real time, thereby helping to obtain comprehensive and accurate satellite energy input data and improve the efficiency and reliability of the energy system.

[0053] Although the embodiments of the present invention have been described above, it should be understood that they are presented only as examples and not as limitations. It will be apparent to those skilled in the relevant art that various combinations, variations, and changes can be made thereto without departing from the spirit and scope of the present invention. Therefore, the breadth and scope of the present invention disclosed herein should not be limited by the exemplary embodiments disclosed above, but should be defined only by the appended claims and their equivalents.

Claims

1. A simulation method for the illumination condition of a spacecraft's solar panel, characterized in that, Including: Generating a point cloud file based on a three-dimensional model of the spacecraft body, and establishing a battery array coordinate grid according to the distribution of the solar cells on the solar panel; Projecting each point in the point cloud file onto the solar panel plane in the direction of the solar vector; Determining the distribution of the points in the point cloud file in the battery array coordinate grid; And Determining the shaded area of the battery array coordinate grid according to the distribution, and obtaining the illumination condition of the solar panel.

2. The simulation method according to claim 1, wherein The density of the point cloud file is determined according to the size of the solar cells on the solar panel.

3. The simulation method according to claim 1, wherein Projecting each point in the point cloud file onto the solar panel plane in the direction of the solar vector includes: Convert the inertial system solar vector S i to this system to obtain S b ; and Rotate the Z-axis of the present system to S b direction.

4. The simulation method according to claim 3, wherein Determining the distribution of the points in the point cloud file in the battery array coordinate grid includes: Rectifying the projection of the battery array coordinate grid on the XY plane of the system into a rectangle; and Judging whether the coordinates of each point in the point cloud file fall within the coordinate ranges at both ends of the X-axis and Y-axis of the rectangle.

5. The simulation method according to claim 4, wherein Determining the distribution of the points in the point cloud file in the battery array coordinate grid further includes: If there is a point on a certain solar cell, judging whether the solar cell is completely blocked.

6. The simulation method according to claim 5, wherein Determining the distribution of the points in the point cloud file in the battery array coordinate grid further includes: Dividing each uncompletely blocked solar cell into N*N grids respectively; Counting the proportion of the grids with points in each solar cell; and Summarizing the proportion of the grids with points in each solar cell, and combining the distribution of the completely blocked solar cells to obtain the distribution of the points in the point cloud file in the battery array coordinate grid.

7. The simulation method according to claim 6, characterized in that, Using the Monte Carlo method, dividing each uncompletely blocked solar cell into N*N grids respectively.

8. The simulation method according to claim 6, characterized in that, The value of N is 10.

9. The simulation method according to claim 1, characterized in that, It also includes: Determining the time periods when the spacecraft enters the earth's shadow and the moon's shadow, and determining the illumination condition of the solar panel based on the distribution of the point cloud file in the battery array coordinate grid during the non-entry time periods of the earth's shadow and the moon's shadow.

10. The simulation method according to any one of claims 1 to 9, characterized in that, Implemented through GPU.

Images