High-fidelity non-conservative force calculation method and system for a lunar orbiter

Abstract

The application provides a high-fidelity lunar orbiter non-conservative force calculation method and system, which comprises the following steps: constructing a discretized orbiter model and a discretized lunar grid model; based on the relative positions of the orbiter, the moon and the sun at a target epoch and the conversion matrix between the orbiter system and the calculation reference system, performing the steps comprising: constructing a light ray image plane model; determining the real light receiving surface of the light ray image plane model and the discretized orbiter model by using a ray tracing technique, calculating the generalized geometric vector of each pixel ray, and then calculating the solar radiation pressure acceleration; discretizing the solar disk, constructing a set of pixels blocked by the moon by using a ray tracing technique to calculate the solar visibility ratio, and correcting the solar radiation pressure acceleration according to the solar visibility ratio; geometrically screening the reflection radiation surface element and the thermal infrared radiation surface element, and combining the generalized geometric vector to calculate the lunar surface reflection radiation acceleration and the lunar surface thermal infrared radiation acceleration respectively; and synthesizing the total non-conservative acceleration.

Description

Technical Field

[0001] This invention belongs to the field of deep space probe orbit dynamics modeling or precise orbit determination technology, specifically involving a high-fidelity method and system for calculating non-conservative forces of a lunar orbiter. Background Technology

[0002] In traditional non-conservative force models, the simplest are the equivalent sphere model or the equivalent cross-sectional area model. These methods reduce the detector to a simplified body with a fixed light-receiving area and reflection characteristics, and estimate the solar radiation pressure acceleration based on solar irradiance and detector mass. In preliminary orbit design, the overall light-receiving characteristics are typically described using the equivalent area and reflection coefficient, simplifying the solar radiation pressure into a perturbation term proportional to the equivalent area / detector mass. However, this approach fails to reflect the influence of detector attitude changes, solar array deployment status, antenna obstruction, protruding structures within the cabin, and the different surface materials of various components on the radiation pressure. For lunar orbiters with large solar arrays, high-gain antennas, and complex extended components, a single equivalent area can only provide an average approximation, which is insufficient to support precise orbit determination requirements.

[0003] In engineering, plate models are commonly used to model solar radiation pressure. A plate model simplifies the detector into several regular flat plates, such as the six faces of the module, solar array panels, high-gain antenna panels, and support panels. Each plate has an area, normal, specular reflection coefficient, and diffuse reflection coefficient. Whether a panel is illuminated is determined by the angle between the solar incident direction and the panel's normal, and then the solar radiation pressure contribution of each plate is calculated. This method is more detailed than the equivalent area model, but its illumination determination usually still relies on the dot product of the surface normal and the incident direction, and cannot determine whether the surface is blocked by other structures. In self-shading configurations, traditional plate models may include solar arrays or module surfaces that are actually in shadow in the illuminated area, thus overestimating the solar radiation pressure acceleration. For a lunar orbiter, when the sun shines from the side and rear, the solar arrays may block local areas of the module, and the high-gain antenna and support may also form shadows; conversely, some recessed or back-facing areas may receive a small amount of radiation through reflection. Traditional plate models cannot simultaneously describe these situations.

[0004] Besides solar radiation pressure, similar simplifications exist in handling lunar eclipse. Traditional methods typically employ conical umbra or penumbra models, determining whether the probe is in the illuminated, umbra, or penumbra region based on the geometric relationship between the sun, moon, and probe, and then correcting for solar radiation pressure using simplified functions. While these models can quickly estimate the entry and exit times of the eclipse, within the penumbra, the apparent solar disk is gradually obscured by the moon. Using only simple geometric boundaries makes it difficult to describe the continuous flux changes caused by partial solar disk obstruction, and also fails to account for pixel weight differences resulting from the dimming of the sun's periphery.

[0005] Traditional methods of treating lunar albedo and thermal infrared radiation typically approximate the Moon as a uniform sphere, a few rings, or a collection of low-resolution surface elements, estimating the average radiation pressure based on parameters such as probe altitude and lunar phase. These approximations neglect local variations in lunar albedo, emissivity, and temperature, and struggle to accurately handle strong spatial variations near the termination line. In reality, lunar albedo originates from regions simultaneously illuminated by the sun and visible to the probe; thermal infrared radiation, on the other hand, comes from the visible lunar surface, including the night side which experiences thermal radiation due to its non-zero temperature.

[0006] The above issues collectively demonstrate that while traditional models are computationally efficient, they suffer from the following main shortcomings:

[0007] (1) The geometric representation is too simplified and cannot describe the complex configuration of the detector;

[0008] (2) Insufficient handling of occlusion relationships makes it impossible to accurately identify the actual light-receiving surface and the self-occluding area;

[0009] (3) The lunar radiation environment is simplified too much, and high-resolution information such as lunar albedo, temperature and shape grid is not fully utilized.

[0010] For high-precision lunar orbiting missions, these errors may manifest as deviations in solar radiation pressure acceleration, discontinuities in flux at the eclipse boundary, inaccurate estimations of lunar surface albedo and thermal infrared radiation, and further affect orbital residuals, estimations of gravity field parameters, and empirical acceleration calculations. Summary of the Invention

[0011] Traditional models inevitably suffer from errors caused by oversimplified geometric representations, insufficient handling of occlusion relationships, and excessive simplification of the lunar radiation environment. These errors manifest as deviations in solar radiation pressure acceleration, discontinuities in flux at the eclipse boundary, and inaccurate estimations of lunar albedo and thermal infrared radiation. Furthermore, these errors affect orbital residuals, gravity field parameter estimations, and empirical acceleration calculations. To overcome these problems, this invention provides a high-fidelity method and system for calculating nonconservative forces on a lunar orbiter. Based on a three-dimensional geometric model of the probe and a lunar triangular mesh model, the complex structures of the probe, such as the cabin, solar panels, and antennas, are discretized into triangular facets with surface optical properties. Simultaneously, the lunar surface is discretized into surface elements with albedo, emissivity, and temperature parameters, thereby enabling the description of realistic geometric occlusion, local illumination conditions, and lunar radiation contributions.

[0012] According to one aspect of the present invention, a method for calculating non-conservative forces of a high-fidelity lunar orbiter is provided, characterized in that it includes:

[0013] Construct a discretized probe model and a discretized lunar grid model;

[0014] Based on the relative positions of the probe, the Moon, and the Sun at the target epoch, and the transformation matrix between the probe's own frame and the calculated reference frame, the execution steps include:

[0015] Construct a ray image plane model; the ray image plane model includes the ray image plane and its plane properties and ray properties;

[0016] Ray tracing technology is used to determine the actual light-receiving surface of the ray image plane model and the discretized detector model, the generalized geometric vector of each pixel ray is calculated, and then the solar radiation pressure acceleration is calculated.

[0017] The solar disk is discretized, and a set of pixels obscured by the moon is constructed using ray tracing technology to calculate the solar visibility ratio. The solar radiation pressure acceleration is then corrected based on the solar visibility ratio.

[0018] Geometric screening is performed on the discretized lunar mesh model to determine the set of albedo radiation elements and the set of thermal infrared radiation elements. The lunar surface albedo acceleration and lunar surface thermal infrared radiation acceleration are calculated respectively by combining generalized geometric vectors.

[0019] The corrected solar radiation pressure acceleration, lunar surface albedo acceleration, and lunar surface thermal infrared radiation acceleration are combined to form the total non-conservative acceleration at the target epoch.

[0020] As a further technical solution, the discretized detector model is a set of triangular facets with additional attributes, and the construction process includes:

[0021] A three-dimensional geometric model of the detector is established based on all its components. This three-dimensional geometric model is then discretized into a set of triangular facets. Each triangular facet is assigned an area, normal, position, and surface optical properties to obtain a discretized detector model.

[0022] As a further technical solution, the process of constructing a ray-like planar model includes:

[0023] Based on the relative position of the detector and the sun at the target epoch, the direction of the sun in the detector system is determined, and a rectangular ray image plane is established on the sun side of the detector and perpendicular to the direction of sunlight incident propagation. The planar properties of the ray image plane are determined, including width, height and pixel spacing. Each pixel in the ray image plane corresponds to a pixel ray, and the propagation direction of each pixel ray is consistent, all pointing from the ray image plane to the detector.

[0024] Based on the width, height, and pixel spacing of the light image plane, the total number of rays in the light image plane and the area represented by a single pixel ray are determined. The starting point, propagation direction, total number of rays, and area represented by a single pixel ray are used as the ray attributes of the light image plane.

[0025] As a further technical solution, the steps for determining the actual light-receiving surface of the ray-image plane model and the discretized detector model using ray tracing technology include:

[0026] Each pixel ray in the light-image plane model is taken as the incident ray. The intersection point between each incident ray and the discretized detector model is solved by the ray tracing kernel. When there is an intersection point, it is confirmed that the incident ray hits the discretized detector model, and the triangular facet that it first hits along the propagation direction is taken as the real light-receiving surface corresponding to the incident ray.

[0027] For each incident ray that has hit the real light-receiving surface, the corresponding specular reflection ray is calculated based on the law of reflection. The specular reflection ray is then used as the next-order incident ray to continue to be input into the ray tracing kernel for intersection loop execution until the next-order incident ray fails to hit the discretized detector model, or the number of reflections of the pixel ray reaches the preset maximum number of reflections threshold.

[0028] As a further technical solution, the generalized geometric vector of each pixel ray is calculated, and the steps include:

[0029] In the process of determining the real light-receiving surface of the ray image plane model and the discretized detector model using ray tracing technology, when a pixel ray hits, the initial order generalized geometric vector is calculated based on the incident direction vector, the direction vector of the specular reflection ray, and the diffuse reflection momentum component along the normal of the hit surface.

[0030] When a pixel ray undergoes multiple reflections, a recursive algorithm is used to calculate the current order generalized geometric vector from the initial order generalized geometric vector.

[0031] As a further technical solution, solar radiation pressure acceleration is calculated based on the generalized geometric vectors of each pixel ray through a radiation pressure acceleration model. The mathematical expression of the radiation pressure acceleration model is as follows:

[0032]

[0033] in, This indicates that the solar radiation pressure acceleration due to lunar obstruction was not taken into account. This indicates the solar irradiance at the probe location; Indicates detector quality; Represents the speed of light in a vacuum; Indicates consideration up to the first The total generalized geometric vector obtained after first-order reflection; The right ascension and declination of the sun in the detector's system.

[0034] As a further technical solution, the solar disk is discretized, and a set of pixels obscured by the moon is constructed using ray tracing technology to calculate the solar visibility ratio. The solar radiation pressure acceleration is then corrected based on the solar visibility ratio. The steps include:

[0035] The solar disk observed by the detector is discretized into a finite number of pixels to construct a total pixel set of the solar disk; based on a preset solar edge dimming calculation function, edge dimming weights are calculated and assigned to each pixel in the total pixel set of the solar disk.

[0036] Starting from the detector position, occlusion determination rays are generated along the direction from the detector to each solar disk pixel. The intersection of the occlusion determination rays and the discretized lunar mesh model is solved using the ray tracing kernel. The lunar occlusion status of each pixel ray is determined, and the pixels occluded by the moon are selected to construct a set of pixels occluded by the moon.

[0037] Based on the total set of pixels of the solar disk, the set of occluded pixels, and the edge dimming weights corresponding to each pixel, the solar visibility ratio is calculated; the solar radiation pressure acceleration is corrected using the solar visibility ratio, and the solar radiation pressure acceleration after considering the lunar occlusion is calculated, that is, the corrected solar radiation pressure acceleration.

[0038] As a further technical solution, the steps for calculating the lunar surface albedo acceleration and the lunar surface thermal infrared radiation acceleration include:

[0039] Centered on the moon's center, In the fixed coordinate system of the lunar center and the sun with the axis pointing to the sun, the set of solar-illuminated lunar surface elements and the set of lunar surface elements visible to the probe of the discretized lunar mesh model are geometrically selected. The intersection of the set of solar-illuminated lunar surface elements and the set of lunar surface elements visible to the probe is taken to obtain the set of albedo elements. The set of lunar surface elements visible to the probe is used as the set of thermal infrared radiation elements.

[0040] Calculate the contribution of each albedo element in the albedo radiation element set to the albedo irradiance generated by the detector, and calculate the contribution of each thermal infrared radiation element in the thermal infrared radiation element set to the thermal infrared irradiance generated by the detector.

[0041] The detector's radiation response to the direction of lunar surface elements is represented by a generalized geometric vector. The lunar surface albedo acceleration is calculated using the albedo irradiance of each albedo element in the set of albedo elements. The lunar surface thermal infrared acceleration is calculated using the thermal infrared irradiance of each thermal infrared radiation element in the set of thermal infrared radiation elements.

[0042] According to another aspect of this specification, a high-fidelity lunar orbiter non-conservative force calculation system is provided to implement a high-fidelity lunar orbiter non-conservative force calculation method, comprising:

[0043] The mathematical modeling module is used to construct discretized probe models and discretized lunar grid models;

[0044] The data input module is used to obtain the relative positions of the probe, the moon, and the sun at the target epoch, as well as the transformation matrix between the probe's own frame and the calculation reference frame;

[0045] The ray image plane modeling module is used to construct a ray image plane model; the ray image plane model includes the ray image plane and its plane properties and ray properties;

[0046] The solar radiation pressure acceleration calculation module is used to determine the real light-receiving surface of the ray image plane model and the discretized detector model using ray tracing technology, calculate the generalized geometric vector of each pixel ray, and then calculate the solar radiation pressure acceleration.

[0047] The solar radiation pressure acceleration correction module is used to discretize the solar disk, construct a set of pixels obscured by the moon using ray tracing technology to calculate the solar visibility ratio, and correct the solar radiation pressure acceleration based on the solar visibility ratio.

[0048] The radiation acceleration calculation module is used to perform geometric screening on the discretized lunar mesh model, determine the set of albedo radiation elements and the set of thermal infrared radiation elements, and calculate the lunar surface albedo radiation acceleration and lunar surface thermal infrared radiation acceleration respectively by combining generalized geometric vectors.

[0049] The output module is used to vector synthesize the corrected solar radiation pressure acceleration, lunar surface albedo acceleration, and lunar surface thermal infrared radiation acceleration to obtain the total non-conservative acceleration of the lunar orbiter.

[0050] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0051] By constructing a discretized 3D model of the probe and a lunar mesh model, and combining ray image plane and ray tracing techniques, the actual illuminated surface, self-occluding region, and multiple reflection paths of the probe can be directly identified, avoiding the simplification errors of traditional equivalent area models and plate models regarding the illuminated state. By discretizing the solar disk and tracing lunar occlusion pixels, the continuously changing solar visible ratio can be obtained, achieving smooth correction of solar radiation pressure acceleration under umbra and penumbra conditions. By geometrically screening lunar albedo and thermal infrared radiation elements, and combining generalized geometric vectors to calculate the probe's response to radiation from different incident directions, the influence of local lunar geometry, albedo, emissivity, and temperature differences on nonconservative forces can be more accurately reflected, thereby improving the accuracy and physical consistency of nonconservative force modeling for lunar orbiters under complex configurations, self-occlusion, eclipse transitions, and non-uniform lunar radiation conditions. Attached Figure Description

[0052] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0053] Figure 1 A flowchart illustrating a method for calculating non-conservative forces of a high-fidelity lunar orbiter provided in an embodiment of the present invention;

[0054] Figure 2 This is a schematic diagram of detector blocking ray tracing in an embodiment of the present invention;

[0055] Figure 3 This is a geometrical schematic diagram of lunar surface albedo radiation in an embodiment of the present invention;

[0056] Figure 4 This is a geometrical diagram of lunar thermal infrared radiation in an embodiment of the present invention;

[0057] Figure 5 This is a schematic diagram of the structure of a high-fidelity lunar orbiter non-conservative force calculation system provided in an embodiment of the present invention. Detailed Implementation

[0058] It should be noted that:

[0059] The terms “comprising” and “having”, and any variations thereof, in the specification, claims, and accompanying drawings of this invention are intended to cover a non-exclusive inclusion, such as a process, method, system, product, or apparatus that includes a series of steps or units, not necessarily limited to those explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0060] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities can be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor devices and / or microcontroller devices. The flowcharts shown in the accompanying drawings are merely illustrative and do not necessarily include all content and operations / steps, nor do they necessarily have to be performed in the described order. For example, some operations / steps can be decomposed, while others can be combined or partially combined; therefore, the actual execution order may change depending on the specific circumstances.

[0061] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. In addition, the technical features of the various embodiments or individual embodiments provided by the present invention can be arbitrarily combined to form new technical solutions. Such combinations are not bound by the order of steps and / or structural composition patterns, but must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0062] like Figure 1 As shown, a method for calculating nonconservative forces of a high-fidelity lunar orbiter includes the following steps:

[0063] Step 1. Construct a discretized probe model and a discretized lunar mesh model;

[0064] The execution steps, based on the relative positions of the probe, the Moon, and the Sun at the target epoch and the transformation matrix between the probe's own frame and the computational reference frame, include:

[0065] Step 2. Construct a ray image plane model based on the incident direction of the sun relative to the detector;

[0066] Step 3. Use ray tracing technology to determine the actual light-receiving surface of the ray image plane model and the discretized detector model, calculate the generalized geometric vector of each pixel ray, and then calculate the solar radiation pressure acceleration;

[0067] Step 4. Discretize the solar disk, construct a set of pixels obscured by the moon using ray tracing technology to calculate the solar visibility ratio, and correct the solar radiation pressure acceleration based on the solar visibility ratio;

[0068] Step 5. Perform geometric screening on the discretized lunar mesh model to determine the set of albedo radiation elements and the set of thermal infrared radiation elements, and calculate the lunar surface albedo acceleration and lunar surface thermal infrared radiation acceleration respectively by combining the generalized geometric vectors.

[0069] Step 6. Vector synthesize the corrected solar radiation pressure acceleration, lunar surface albedo acceleration, and lunar surface thermal infrared radiation acceleration to obtain the total non-conservative acceleration of the lunar orbiter.

[0070] In step 1, the discretized detector model is a set of triangular facets with additional attributes. The construction process includes:

[0071] A three-dimensional geometric model of the detector is established based on all its components. This three-dimensional geometric model is then discretized into a set of triangular facets. Each triangular facet is assigned area, normal, position, and surface optical properties to obtain a discretized detector model. This model is able to describe the contribution of different components to non-conservative forces under complex configurations.

[0072] The detector of the present invention is assumed to be a lunar orbiter, and its components include at least a cabin, solar panels and an antenna.

[0073] Specifically, the detector model is discretized into a set of triangular facets, mathematically represented as:

[0074]

[0075] In the formula, Represents a discretized detector model; Indicates the first A triangular piece, a triangular piece It has the following properties: centroid External normal direction ,area Specular reflectance and diffuse reflectance ; This indicates the total number of triangular facets.

[0076] In step 1, the discretized lunar mesh model is a set of triangular facets with additional attributes. The construction process includes:

[0077] A lunar triangular mesh model is obtained and discretized into a set of triangular facets. Albedo, emissivity, and temperature attributes are added to each triangular facet. The high-precision variation of lunar surface albedo is fully considered to obtain a discretized lunar mesh model.

[0078] The lunar triangular mesh model can be a spherical mesh model or a mesh model with the actual shape of the moon.

[0079] In this embodiment, the mathematical representation of the discretized lunar mesh model is as follows:

[0080]

[0081] In the formula, Represents a discretized lunar mesh model; Indicates the first Each triangular facet has the following properties: facet centroid. Surface element external normal Surface area Albedo Surface element emissivity Dough temperature ; This represents the total number of triangular facets.

[0082] Step 2, the process of constructing the ray-image plane model includes:

[0083] The mathematical representations of the detector's local coordinate system and the image plane coordinate system are as follows:

[0084]

[0085] In the formula, Indicates the coordinate system of the detector body. These are the X, Y, and Z axis coordinate components of the detector within its own system. Represents a plane coordinate system. These are the X, Y, and Z axis coordinate components in the image plane coordinate system.

[0086] Right ascension is determined based on the direction of the sun's incidence within the probe's system. and declination Transformation matrix Used to set local coordinates of the image plane Transform to detector local coordinates Mathematically, this is expressed as:

[0087]

[0088]

[0089] In the formula, Indicates right ascension, Indicates the right ascension of rotation about the Z-axis ; Indicates declination, Indicates negative declination rotation about the Y-axis ; It is the direction vector of the image plane center, that is, the position vector of the image plane origin in the detector system; is the distance from the origin of the image plane to the origin of the detector's local coordinate system. Wherein, The dimensions of the image plane should be selected according to the size of the target detector: the image plane must be completely outside the detector, and the width and height of the image plane should cover the complete projection of the target detector in the incident direction. Preferably, Take the maximum envelope size of the detector times.

[0090] In step 2, the ray image plane model includes the ray image plane and its planar and ray properties. The construction process includes:

[0091] Step 2-1: Based on the relative position of the detector and the sun at the target epoch, determine the direction of the sun in the detector's system, establish a rectangular ray image plane located on the sun side of the detector and perpendicular to the direction of sunlight incident propagation, and determine the planar attributes of the ray image plane, including: width, height, and pixel spacing; each pixel in the ray image plane corresponds to a pixel ray, and the propagation direction of each pixel ray is consistent, all pointing from the ray image plane to the detector;

[0092] Step 2-2: Based on the width, height, and pixel spacing of the light image plane, determine the total number of rays in the light image plane and the area represented by a single pixel ray. The starting point, propagation direction, total number of rays, and area represented by a single pixel ray are used as the ray attributes of the light image plane.

[0093] Among them, the direction of the sun in the detector's main system is from right ascension. and declination This indicates that the direction is determined by the relative position vector of the detector pointing towards the sun; the light image plane is set on the sun side of the detector, and the propagation direction of each pixel ray is from the origin of the light image plane to the origin of the detector, and is consistent with the incident propagation direction of sunlight.

[0094] The basic idea of ​​ray source modeling is to discretize the approximately parallel incident radiation from a distance into a rectangular image plane, where each pixel corresponds to a ray, and all rays have the same direction and are equal to... That is, the direction from the origin of the image plane of the light rays to the origin of the detector:

[0095]

[0096] In the formula, , These are the position vectors of the sun and the probe in the same coordinate system;

[0097] The direction of sunlight radiation propagation (the direction of incident sunlight) is:

[0098]

[0099] In step 2-1, the ray image plane model discretizes the starting point of sunlight into ray image planes, and the ray image plane contains the first... The mathematical representation of the reference coordinates of each pixel is:

[0100]

[0101] In the formula, Represents the first ray in the image plane Reference coordinates for each pixel; The width of the light image plane, The height of the ray image plane is; The pixel spacing of the light image plane.

[0102] After rotation and translation using a transformation matrix, the ray in the image plane is... The coordinates of each pixel in the detector's local system are:

[0103]

[0104] In the formula, Represents the first ray in the image plane The coordinates of each pixel within the detector's own system.

[0105] In step 2-2, the total number of rays Represented as:

[0106]

[0107] use Let ray density, i.e., the number of rays per unit area, be expressed as follows:

[0108]

[0109] Area represented by a single pixel ray for:

[0110]

[0111] Step 3, which uses ray tracing technology to determine the actual light-receiving surface of the ray-image plane model and the discretized detector model, includes:

[0112] Step 3-1-1: Take each pixel ray in the light image plane model as the incident ray, and use the ray tracing kernel to solve the intersection point between each incident ray and the discretized detector model. When there is an intersection point, it is confirmed that the incident ray hits the discretized detector model, and the triangular facet that it first hits along the propagation direction is taken as the real light-receiving surface corresponding to the incident ray.

[0113] Step 3-1-2: For each incident ray that has hit the real light-receiving surface, calculate its corresponding specular reflection ray based on the law of reflection, and use the specular reflection ray as the next order incident ray to continue inputting it into the ray tracing kernel for intersection.

[0114] Step 3-1-3: Repeat step 3-1-2 until the next incident ray fails to hit the discretized detector model, or the number of reflections of the pixel ray reaches the preset maximum reflection threshold.

[0115] Specifically, in step 3-1-1, in the ray-like plane model, the first... The mathematical representation of a pixel ray is:

[0116]

[0117] in, For the first The starting point of a pixel ray corresponds to a pixel in the image plane of the ray. In the coordinates of the detector's own system, For ray parameters, For the first The propagation direction of each pixel ray. Since the pixel rays in the image plane are parallel to each other, they all have the same propagation direction, that is:

[0118]

[0119] In the formula, It represents the direction vector from the origin of the image plane of the light rays to the origin of the detector.

[0120] Solving the first problem using a ray-tracing kernel The intersection point between the pixel ray and the detector triangular mesh. If the pixel ray intersects the detector triangular mesh at one or more points, the intersection point closest to the ray's origin along the ray's propagation direction is selected as the first intersection point. Its mathematical representation is:

[0121]

[0122] If the pixel ray first hits the face... Then the patch is considered to be affected by the incident radiation corresponding to the pixel ray, and is considered as a ray. The corresponding real light-receiving surface only records the first hit result along the ray propagation direction during ray tracing, thus automatically excluding areas blocked by other components, thereby handling the self-occlusion problem in complex configurations.

[0123] In step 3-1-2, if the first A ray in direction Hit the face The normal direction of the surface is Then the direction of mirror reflection for

[0124]

[0125] The formula for the direction of reflection is:

[0126]

[0127] in Let be the incident unit vector. To hit the outer normal direction of the face, This is the direction cosine of the incident direction and the normal to the surface. The reflected rays can be further fed into the ray tracing kernel to determine whether a secondary or higher-order reflection has occurred.

[0128] like Figure 2 As shown, the pixel rays of the planar model are input into the ray tracing module, and their intersection with the 3D mesh (discrete detector model) of the detector in the current attitude is calculated. The ray tracing module determines the triangular facets first hit by each ray and records the facet number, intersection point position, incident direction, and facet normal. This yields the actual illuminated area and excludes facets blocked by components such as solar panels, the fuselage, or antennas. If multiple reflections are considered, the reflected rays after the first hit are used as new rays and input into the ray tracing module to determine whether they hit other components again.

[0129] In step 3, the generalized geometric vector of each pixel ray is calculated. The steps include:

[0130] Step 3-2-1: In the process of determining the real light-receiving surface of the ray image plane model and the discretized detector model using ray tracing technology, when the pixel ray hits the detector surface for the first time, the initial order generalized geometric vector of the pixel ray is calculated based on the incident direction vector, the specular reflection direction vector, and the diffuse reflection momentum component along the outward normal direction of the hit surface.

[0131] Step 3-2-2: When a pixel ray is reflected multiple times, the reflected ray generated after the previous hit is taken as the incident ray of the current order. Combined with the outward normal of the currently hit patch, the surface optical properties, and the flux retention ratio, the generalized geometric vector of the current order is recursively calculated.

[0132] Specifically, in step 3-2-1, for a single reflection, i.e., considering only the first interaction between external light and the detector surface, the initial order generalized geometric vector is... The mathematical representation of is:

[0133]

[0134] in, This represents the number of rays that actually hit the discretized detector model (hereinafter referred to as "hit" in the formula explanation section). , , The first The specular reflectance, diffuse reflectance, and outward normal of the facet corresponding to each pixel ray, and the area corresponding to each pixel ray. .

[0135] In step 3-2-2, the recursive calculation of each order is based on the reflected rays generated after the previous order hit and their flux retention ratio. If it hits the detector surface again, the momentum contribution generated by specular reflection and diffuse reflection of this order is calculated according to the geometric properties, surface optical properties and flux retention ratio of the currently hit patch, and the contributions of each order are accumulated to obtain the total generalized geometric vector.

[0136] consider At the second reflection, the generalized geometric vector of order b is recursively given as:

[0137]

[0138] in, The number of incident rays generated and hit by mirror reflection; This represents the number of incident rays generated and hit by diffuse reflection sampling. This is the preset number of rays for each diffuse reflection sample; This indicates that the incident ray experienced the previous The percentage of external incident flux retained after a second hit.

[0139] Furthermore, in step 3, the solar radiation pressure acceleration is calculated based on the generalized geometric vectors of each pixel ray through a radiation pressure acceleration model. The mathematical expression of the radiation pressure acceleration model is as follows:

[0140]

[0141] in, This indicates that the solar radiation pressure acceleration due to lunar obstruction was not taken into account. This indicates the solar irradiance at the probe location; Indicates detector quality; Represents the speed of light in a vacuum; Indicates consideration up to the first The total generalized geometric vector obtained after first-order reflection; The right ascension and declination of the sun in the detector's system.

[0142] Among them, the solar irradiance at the detector The calculation formula is:

[0143]

[0144] in, The solar constant at 1 AU; The distance from the detector to the sun is expressed in AU.

[0145] Therefore, step 3 of the present invention provides a method for identifying the real illuminated surface based on ray tracing: the light rays generated by the pixel plane are intersected with the three-dimensional triangular mesh of the detector, and the first hit surface, intersection position, incident direction and surface normal of each ray are recorded. The first hit result is used as the criterion for the real illuminated surface, thereby automatically excluding areas blocked by the solar panel, cabin, antenna or support; for the light rays that hit the detector surface for the first time, the reflection direction is calculated according to the surface normal and specular reflection coefficient, and the reflected light rays are continued to be input into the ray tracing module to determine whether they hit other surfaces again (multiple hits).

[0146] On the other hand, a method for identifying self-occlusion in complex configurations is provided: the occlusion relationship between detector components is determined by the intersection of light rays and a 3D model. For surfaces that face the sun but are blocked by other structures, the solar radiation pressure contribution is not included; for surfaces that are not blocked and are hit by light for the first time, the actual light-receiving surface is included, thereby improving the accuracy of solar radiation pressure calculation for complex configuration detectors. Based on this, the solar radiation pressure contribution is accumulated by one or more reflection paths, realizing the solar radiation pressure calculation considering multiple reflections of components such as the cabin, solar array, and antenna.

[0147] It is worth noting that the solar radiation pressure acceleration of each pixel ray obtained in step 3 is the ideal calculation result when there is no lunar obstruction. However, the lunar orbiter may enter the lunar umbra or penumbra. In order to calculate the eclipse transition, further correction in step 4 is required.

[0148] In step 4, the solar disk is discretized, and a set of pixels obscured by the moon is constructed using ray tracing technology to calculate the solar visibility ratio. The solar radiation pressure acceleration is then corrected based on the solar visibility ratio. The steps include:

[0149] Step 4-1: Discretize the solar disk observed by the detector into a finite number of pixels to construct a total pixel set of the solar disk; based on a preset solar edge dimming calculation function, calculate and assign edge dimming weights to each pixel in the total pixel set of the solar disk.

[0150] Step 4-2: Using the detector position as the starting point of the ray, generate occlusion determination rays along the direction from the detector to each solar disk pixel. Use the ray tracing kernel to solve for the intersection between the occlusion determination ray and the discretized lunar mesh model. If there is an intersection between the occlusion determination ray and the discretized lunar mesh model, it is determined that the solar disk pixel is occluded by the moon and added to the set of pixels occluded by the moon.

[0151] Step 4-3: Based on the total set of pixels of the solar disk, the set of pixels obscured by the moon, and the edge dimming weights corresponding to each pixel of the solar disk, calculate the solar visibility ratio; use the solar visibility ratio to correct the solar radiation pressure acceleration, and calculate the solar radiation pressure acceleration after considering the moon's obscuration, that is, the corrected solar radiation pressure acceleration.

[0152] In step 4-1, considering the solar rim dimming effect, a rim dimming weight is assigned to each pixel in the total pixel set of the solar disk. For the first pixel on the solar disk... Each pixel, edge dimming weight The mathematical representation of is:

[0153]

[0154] In the formula, The number of pixels on the solar disk; Calculate the function for when the sun is near the edge and dim; Represents the surface of the sun. The emission angle of each pixel relative to the viewing direction.

[0155] The function for calculating dimness near the sun expands to:

[0156]

[0157] In step 4-3, the edge shading weight is calculated based on the pixel position of the solar disk and the edge shading function, mathematically expressed as:

[0158]

[0159] In the formula, The visible scale of the sun; The total set of pixels of the solar disk; The set of pixels obscured by the moon; Represents the first on the solar disk The edge dimming weight of each pixel.

[0160] The solar radiation pressure after the moon blocks the sunlight is:

[0161]

[0162] Step 5, which involves calculating the lunar surface albedo acceleration and the lunar surface thermal infrared radiation acceleration, includes the following steps:

[0163] Step 5-1, with the center of the moon as the center, In the fixed coordinate system of the lunar center and the sun with the axis pointing to the sun, the set of solar-illuminated lunar surface elements and the set of lunar surface elements visible to the probe of the discretized lunar mesh model are geometrically selected. The intersection of the set of solar-illuminated lunar surface elements and the set of lunar surface elements visible to the probe is taken to obtain the set of albedo elements. The set of lunar surface elements visible to the probe is used as the set of thermal infrared radiation elements.

[0164] Step 5-2: Calculate the contribution of each albedo surface element in the albedo radiation element set to the albedo irradiance generated by the detector, and calculate the contribution of each thermal infrared radiation surface element in the thermal infrared radiation element set to the thermal infrared irradiance generated by the detector.

[0165] Step 5-3: Use generalized geometric vectors to characterize the detector's response characteristics to radiation from lunar surface elements, and calculate the lunar surface albedo acceleration based on the albedo irradiance contribution of each albedo element, and calculate the lunar surface thermal infrared radiation acceleration based on the thermal infrared irradiance contribution of each thermal infrared radiation element.

[0166] In step 5-1, the lunar-solar fixed coordinate system is centered on the center of the moon. The axis points to the sun, mathematically represented as: , This indicates a fixed coordinate system centered on the moon and the sun. These are the X, Y, and Z axis coordinate components in the lunar-solar fixed coordinate system.

[0167] Specifically, in step 5-1, the geometric selection of the set of solar and lunar surface elements is mathematically represented as follows:

[0168]

[0169] In the formula, Represents the set of elements on the surface of the sun and moon. Indicates the first The position vector of the centroid of each surface element in the lunar-centered solar orientation coordinate system.

[0170] The geometric selection of the set of lunar surface elements visible to the probe is mathematically represented as follows:

[0171]

[0172] In the formula, This represents the set of lunar surface elements visible to the probe. Indicates the first The unit outward normal of each face element; By the The unit direction vector pointing from each surface element to the detector is mathematically represented as:

[0173]

[0174] In the formula, This represents the position vector of the probe in the fixed coordinate system of the moon and the sun.

[0175] Albedo radiation originates only from lunar surface regions that are both illuminated by the sun and visible to the probe; that is, in actual calculations, the albedo element set. The intersection of the set of lunar surface elements illuminated by sunlight and the set of lunar surface elements visible to the detector can be mathematically represented as:

[0176]

[0177] The thermal infrared radiation comes from all the lunar surface elements visible to the detector, without requiring these elements to be in a state of illumination. In other words, the set of thermal infrared radiation elements is the set of lunar surface elements visible to the detector, mathematically represented as:

[0178]

[0179] Specifically, in step 5-2, the calculation process for the albedo irradiance of a single lunar surface element is as follows:

[0180] In this invention, it is assumed that the lunar surface is a Lambertian reflector, then the first... Albedo irradiance generated by lunar surface elements at the detector for:

[0181]

[0182] in, The albedo of the surface element; Solar irradiance at the Moon; The area of ​​the face unit; The distance from the surface element to the detector; Indicates the first The angle of incidence of the sun on the lunar surface; Indicates the first The lunar surface element points to the exit angle of the detector.

[0183] Supplementary explanation of the formula: In the formula, This represents the effective incident flux of solar irradiance onto a lunar surface element. ,Right now Furthermore, Indicates lunar surface reflected power : .

[0184] Solar irradiance at the Moon The mathematical representation of is:

[0185]

[0186] in, It is the solar constant of 1 AU, with a standard value of 1367±7 W / m²; The sun's position vector, This is the lunar position vector.

[0187] No. The angle of incidence of the sun on the lunar surface Cosine, used to reflect the effective illumination area received by a surface element, is mathematically represented as:

[0188]

[0189] in, Indicates the first The outer normal direction of the monthly surface unit; This represents the unit direction vector pointing from the center of the moon to the sun.

[0190] When using the lunar-centered solar orientation coordinate system, and When the axis points towards the sun, we have:

[0191]

[0192] Therefore, in the lunar-centered solar fixed system, it can be approximately written as:

[0193]

[0194] in, Indicates the first The component of the outward normal of each facet unit on the solar direction axis.

[0195] The lunar surface element points to the launch angle of the probe. Cosine, used to reflect the energy intensity reflected from the surface element towards the detector, is mathematically expressed as:

[0196]

[0197] Distance from surface element to detector Mathematically represented as:

[0198]

[0199] Specifically, in step 5-2, the calculation process for the thermal infrared irradiance of a single lunar surface element includes:

[0200] According to the Stefan-Boltzmann law, its thermal radiative exitance per unit area for:

[0201]

[0202] in, Indicates the first The surface temperature of each element; Indicates the first Emissivity of each element; This is the Stefan-Boltzmann constant, with values ​​ranging from 1 to 10. .

[0203] Then the first The thermal infrared irradiance generated by each surface element towards the detector is calculated using the following formula:

[0204]

[0205] in, For the first The area of ​​each face element.

[0206] As a supplement, surface element temperature The data is provided by the lunar surface temperature model. Optionally, if a simple day-night temperature model is used for the lunar surface temperature model, the... The mathematical representation of the surface temperature of an element is:

[0207]

[0208] The constant temperature of the solar radiation element. The constant temperature of the night surface element is given.

[0209] If the lunar surface temperature model adopts a heat balance model, then the mathematical expression of the temperature of the solar radiation element is:

[0210]

[0211] in Albedo, For emission rate, The solar irradiance at the lunar surface is given. This model assumes that the lunar surface reaches instantaneous thermal equilibrium, meaning that the absorbed solar radiation energy equals the thermal infrared radiation energy, and is only applicable to the sunlit area; for the night surface area, an empirical temperature model or a given constant temperature is still required.

[0212] If the lunar surface temperature model uses measured or a priori temperature maps, the temperature is interpolated to the centroids of each triangular facet element in the discretized lunar mesh model based on the lunar surface latitude and longitude.

[0213] Specifically, in step 5-3, the detector's response to lunar surface elements is represented by a generalized geometric vector. direction The radiation response.

[0214] Firstly, the steps for calculating albedo acceleration include:

[0215] Single lunar surface element The acceleration generated Mathematically, this is expressed as:

[0216]

[0217] In the formula, It represents a generalized geometric vector that describes the response characteristics of the detector surface to radiation; Represents the speed of light;

[0218] Total albedo acceleration Mathematically, this is expressed as:

[0219]

[0220] Preferably, to improve computational efficiency, some components in the above formula are packaged into a unit irradiance response. and geometric factors :

[0221]

[0222]

[0223] The total albedo acceleration is:

[0224]

[0225] Secondly, the steps for calculating thermal infrared radiation acceleration include:

[0226] Thermal infrared radiation acceleration of a single surface element The calculation formula is:

[0227]

[0228] Total thermal infrared radiation acceleration The calculation formula is:

[0229]

[0230] Preferably, if unit irradiance response is used Second geometric factor Then it can be written as:

[0231]

[0232] Specifically, the calculations of lunar surface albedo and thermal infrared radiation are based on a lunar triangular mesh model. For example... Figure 3 and Figure 4As shown, for albedo radiation, lunar surface elements that simultaneously satisfy the conditions of being illuminated by the sun and visible to the detector are first selected; for thermal infrared radiation, all lunar surface elements visible to the detector are selected, because the night surface, although cooler, still produces thermal radiation. Subsequently, the radiative flux reaching the detector is calculated based on the area, normal, distance to the detector, albedo, emissivity, and temperature of each lunar surface element. The radiation direction is then transformed to the detector's own system, and the radiation pressure response of the detector in that direction is calculated. Both albedo radiation and thermal infrared radiation are obtained by integrating the flux contribution of each surface element.

[0233] Step 5 of this invention provides a method for calculating albedo radiation based on lunar surface elements: A lunar triangular mesh model is introduced, with each triangular element assigned a corresponding albedo, fully considering the high-precision variations in lunar albedo. Lunar surface elements illuminated by the sun and visible to the probe are used as albedo radiation sources, and the albedo contribution is calculated element by element.

[0234] Furthermore, a method for calculating thermal infrared radiation based on lunar surface temperature and emissivity is proposed: lunar surface elements visible to the detector are used as thermal infrared radiation sources, and the thermal infrared flux contribution is calculated based on the temperature, emissivity, area, normal, and distance to the detector of each surface element; this method does not require the surface elements to be in the illuminated area, and the surface elements in the dark area can still generate thermal infrared radiation contributions when they have a non-zero temperature.

[0235] As a supplement, for lunar surface albedo and thermal infrared radiation, each lunar surface element is an independent radiation source, and the conversion of the lunar surface element's radiation direction to the detector's own system needs to be considered. Let the... Radiation vector from lunar surface element to detector The mathematical representation of is:

[0236]

[0237] make Let be the rotation matrix from the lunar-centered solar fixed frame to the detector's own frame, then the radiation direction of the surface element under the detector's own frame is... Represented as:

[0238]

[0239] in:

[0240]

[0241] In the formula, for The three orthogonal components in the body coordinate system are the X, Y, and Z axis components.

[0242] Calculate the orientation angle corresponding to this surface element based on the orientation vector of the detector's local system:

[0243]

[0244] in, This represents the latitudinal angle of the lunar surface element orientation within the detector's main system. This indicates the corresponding meridional angle.

[0245] In step 6, based on the above model, the precise calculation of the non-conservative forces of the lunar orbiter can be summarized as follows:

[0246]

[0247] The implementation of the various embodiments of the present invention is based on programmed processing through a system with processor functionality. Therefore, in practical engineering, the technical solutions and functions of the various embodiments of the present invention are encapsulated into various modules. Based on this reality, and building upon the above embodiments, the embodiments of the present invention provide a high-fidelity lunar orbiter non-conservative force calculation system, which is used to execute a high-fidelity lunar orbiter non-conservative force calculation method from the above method embodiments.

[0248] See Figure 5 The system includes:

[0249] The mathematical modeling module is used to construct discretized probe models and discretized lunar grid models;

[0250] The data input module is used to obtain the relative positions of the probe, the moon, and the sun at the target epoch, as well as the transformation matrix between the probe's own frame and the calculation reference frame;

[0251] The ray image plane modeling module is used to construct a ray image plane model; the ray image plane model includes the ray image plane and its plane properties and ray properties;

[0252] The solar radiation pressure acceleration calculation module is used to determine the real light-receiving surface of the light image plane model and the discretized detector model using ray tracing technology, calculate the generalized geometric vector of each pixel ray, and then calculate the solar radiation pressure acceleration without considering the lunar obstruction condition.

[0253] The solar radiation pressure acceleration correction module is used to discretize the solar disk, determine the occlusion relationship between the solar disk pixels and the discretized lunar mesh model through ray tracing technology, construct a set of pixels occluded by the moon, calculate the solar visibility ratio, and correct the solar radiation pressure acceleration based on the solar visibility ratio.

[0254] The radiation acceleration calculation module is used to perform geometric screening on the discretized lunar mesh model, determine the set of albedo radiation elements and the set of thermal infrared radiation elements, and calculate the lunar surface albedo radiation acceleration and lunar surface thermal infrared radiation acceleration respectively by combining generalized geometric vectors.

[0255] The output module is used to vector synthesize the corrected solar radiation pressure acceleration, lunar surface albedo acceleration, and lunar surface thermal infrared radiation acceleration to obtain the total non-conservative acceleration of the lunar orbiter.

[0256] It should be noted that the system embodiments provided by the present invention are used not only to implement the methods in the above method embodiments, but also to implement the methods in other method embodiments provided by the present invention. The only difference is that corresponding functional modules are set. The principle is basically the same as that of the above system embodiments provided by the present invention. As long as those skilled in the art can improve the modules in the above system embodiments by referring to the specific technical solutions in other method embodiments and combining technical features to obtain corresponding technical means and technical solutions composed of these technical means, on the basis of the above system embodiments, and on the premise of ensuring the practicality of the technical solutions, they can obtain corresponding system-like embodiments for implementing the methods in other method-like embodiments.

[0257] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the technical solutions of the embodiments of the present invention.

Claims

1. A method for calculating non-conservative forces on a high-fidelity lunar orbiter, characterized in that, include: Construct a discretized probe model and a discretized lunar grid model; Based on the relative positions of the probe, the Moon, and the Sun at the target epoch, and the transformation matrix between the probe's own frame and the calculated reference frame, the execution steps include: Construct a ray image plane model; the ray image plane model includes the ray image plane and its plane properties and ray properties; Ray tracing technology is used to determine the actual light-receiving surface of the ray image plane model and the discretized detector model, the generalized geometric vector of each pixel ray is calculated, and then the solar radiation pressure acceleration is calculated. The solar disk is discretized, and a set of pixels obscured by the moon is constructed using ray tracing technology to calculate the solar visibility ratio. The solar radiation pressure acceleration is then corrected based on the solar visibility ratio. Geometric screening is performed on the discretized lunar mesh model to determine the set of albedo radiation elements and the set of thermal infrared radiation elements. The lunar surface albedo acceleration and lunar surface thermal infrared radiation acceleration are calculated respectively by combining generalized geometric vectors. By vector combining the corrected solar radiation pressure acceleration, lunar surface albedo acceleration, and lunar surface thermal infrared radiation acceleration, the total non-conservative acceleration of the lunar orbiter is obtained.

2. The method for calculating non-conservative forces of a high-fidelity lunar orbiter as described in claim 1, characterized in that, The discretized detector model is a set of triangular facets with additional attributes, and the construction process includes: A three-dimensional geometric model of the detector is established based on all its components. This three-dimensional geometric model is then discretized into a set of triangular facets. Each triangular facet is assigned an area, normal, position, and surface optical properties to obtain a discretized detector model.

3. The method for calculating non-conservative forces of a high-fidelity lunar orbiter as described in claim 1, characterized in that, The process of constructing a ray-like planar model includes: Based on the relative position of the detector and the sun at the target epoch, the direction of the sun in the detector system is determined, and a rectangular ray image plane is established on the sun side of the detector and perpendicular to the direction of sunlight incident propagation. The planar properties of the ray image plane are determined, including width, height and pixel spacing. Each pixel in the ray image plane corresponds to a pixel ray, and the propagation direction of each pixel ray is consistent, all pointing from the ray image plane to the detector. Based on the width, height, and pixel spacing of the light image plane, the total number of rays in the light image plane and the area represented by a single pixel ray are determined. The starting point, propagation direction, total number of rays, and area represented by a single pixel ray are used as the ray attributes of the light image plane.

4. The method for calculating non-conservative forces of a high-fidelity lunar orbiter as described in claim 1, characterized in that, The steps for determining the actual light-receiving surface of the ray-tracing image plane model and the discretized detector model using ray tracing technology include: Each pixel ray in the light-image plane model is taken as the incident ray. The intersection point between each incident ray and the discretized detector model is solved by the ray tracing kernel. When there is an intersection point, it is confirmed that the incident ray hits the discretized detector model, and the triangular facet that it first hits along the propagation direction is taken as the real light-receiving surface corresponding to the incident ray. For each incident ray that has hit the real light-receiving surface, the corresponding specular reflection ray is calculated based on the law of reflection. The specular reflection ray is then used as the next-order incident ray to continue to be input into the ray tracing kernel for intersection loop execution until the next-order incident ray fails to hit the discretized detector model, or the number of reflections of the pixel ray reaches the preset maximum number of reflections threshold.

5. The method for calculating non-conservative forces of a high-fidelity lunar orbiter as described in claim 1, characterized in that, The generalized geometric vectors of each pixel ray are calculated, and the steps include: In the process of determining the real light-receiving surface of the ray image plane model and the discretized detector model using ray tracing technology, when a pixel ray hits, the initial order generalized geometric vector is calculated based on the incident direction vector, the direction vector of the specular reflection ray, and the diffuse reflection momentum component along the normal of the hit surface. When a pixel ray undergoes multiple reflections, a recursive algorithm is used to calculate the current order generalized geometric vector from the initial order generalized geometric vector.

6. The method for calculating non-conservative forces of a high-fidelity lunar orbiter as described in claim 1, characterized in that, The solar radiation pressure acceleration is calculated based on the generalized geometric vectors of each pixel ray through a radiation pressure acceleration model. The mathematical expression of the radiation pressure acceleration model is as follows: ； in, This indicates that the solar radiation pressure acceleration due to lunar obstruction was not taken into account; This indicates the solar irradiance at the probe location; Indicates detector quality; Represents the speed of light in a vacuum; Indicates consideration up to the first The total generalized geometric vector obtained after first-order reflection; The right ascension and declination of the sun in the detector's system.

7. The method for calculating non-conservative forces of a high-fidelity lunar orbiter as described in claim 1, characterized in that, The solar disk is discretized, and a set of pixels obscured by the moon is constructed using ray tracing technology to calculate the solar visibility ratio. The solar radiation pressure acceleration is then corrected based on this ratio. The steps include: The solar disk observed by the detector is discretized into a finite number of pixels to construct a total pixel set of the solar disk; based on a preset solar edge dimming calculation function, edge dimming weights are calculated and assigned to each pixel in the total pixel set of the solar disk. Starting from the detector position, occlusion determination rays are generated along the direction from the detector to each solar disk pixel. The intersection of the occlusion determination rays and the discretized lunar mesh model is solved using the ray tracing kernel. The lunar occlusion status of each pixel ray is determined, and the pixels occluded by the moon are selected to construct a set of pixels occluded by the moon. Based on the total set of pixels of the solar disk, the set of occluded pixels, and the edge dimming weights corresponding to each pixel, the solar visibility ratio is calculated; the solar radiation pressure acceleration is corrected using the solar visibility ratio, and the solar radiation pressure acceleration after considering the lunar occlusion is calculated, that is, the corrected solar radiation pressure acceleration.

8. The method for calculating non-conservative forces of a high-fidelity lunar orbiter as described in claim 1, characterized in that, The steps for calculating lunar surface albedo acceleration and lunar surface thermal infrared radiation acceleration include: Centered on the moon's center, In the fixed coordinate system of the lunar center and the sun with the axis pointing to the sun, the set of solar-illuminated lunar surface elements and the set of lunar surface elements visible to the probe of the discretized lunar mesh model are geometrically selected. The intersection of the set of solar-illuminated lunar surface elements and the set of lunar surface elements visible to the probe is taken to obtain the set of albedo elements. The set of lunar surface elements visible to the probe is used as the set of thermal infrared radiation elements. Calculate the contribution of each albedo element in the albedo radiation element set to the albedo irradiance generated by the detector, and calculate the contribution of each thermal infrared radiation element in the thermal infrared radiation element set to the thermal infrared irradiance generated by the detector. The detector's radiation response to the direction of lunar surface elements is represented by a generalized geometric vector. The lunar surface albedo acceleration is calculated using the albedo irradiance of each albedo element in the set of albedo elements. The lunar surface thermal infrared acceleration is calculated using the thermal infrared irradiance of each thermal infrared radiation element in the set of thermal infrared radiation elements.

9. A high-fidelity lunar orbiter non-conservative force calculation system, used to implement the high-fidelity lunar orbiter non-conservative force calculation method according to any one of claims 1-8, characterized in that, include: The mathematical modeling module is used to construct discretized probe models and discretized lunar grid models; The data input module is used to obtain the relative positions of the probe, the moon, and the sun at the target epoch, as well as the transformation matrix between the probe's own frame and the calculation reference frame; The ray image plane modeling module is used to construct a ray image plane model; the ray image plane model includes the ray image plane and its plane properties and ray properties; The solar radiation pressure acceleration calculation module is used to determine the real light-receiving surface of the ray image plane model and the discretized detector model using ray tracing technology, calculate the generalized geometric vector of each pixel ray, and then calculate the solar radiation pressure acceleration. The solar radiation pressure acceleration correction module is used to discretize the solar disk, construct a set of pixels obscured by the moon using ray tracing technology to calculate the solar visibility ratio, and correct the solar radiation pressure acceleration based on the solar visibility ratio. The radiation acceleration calculation module is used to perform geometric screening on the discretized lunar mesh model, determine the set of albedo radiation elements and the set of thermal infrared radiation elements, and calculate the lunar surface albedo radiation acceleration and lunar surface thermal infrared radiation acceleration respectively by combining generalized geometric vectors. The output module is used to vector synthesize the corrected solar radiation pressure acceleration, lunar surface albedo acceleration, and lunar surface thermal infrared radiation acceleration to obtain the total non-conservative acceleration of the lunar orbiter.

Images