Solar unmanned aerial vehicle double-sided power generation wing structure and optimization method thereof

Abstract

The invention provides a solar unmanned aerial vehicle double-sided power generation wing structure and an optimization method thereof, and belongs to the technical field of solar unmanned aerial vehicles, the solar unmanned aerial vehicle double-sided power generation wing structure comprises a wing, a double-sided solar cell module and a lower skin, the interior of the wing is of a hollow structure, and the wing comprises a front edge, a main beam, wing ribs, a supporting transverse strip and a rear edge; the rear edge is provided with a bonding area of the double-sided solar cell module, and the double-sided solar cell module is fixedly installed between the rear edge and the front edge. The method comprises the steps of establishing a basic power generation efficiency matrix, optimizing wing rib distribution and constructing a first structure change matrix, adjusting supporting transverse strips to be in fan-shaped distribution to construct a second change matrix, replacing a high-light-transmittance polyester film lower skin to construct a first reverse change matrix, and optimizing the thickness gradient of a PMI foam substrate to construct a second reverse change matrix. And carrying out superposition analysis, constructing an optimal change matrix, forming a final optimization design, and realizing collaborative optimization of the wing structure and the double-sided power generation efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of solar drones. Specifically, it relates to a double-sided generator wing structure for solar drones and an optimization method thereof. Background Art

[0002] A solar drone is a new type of aircraft that uses solar cells to convert sunlight into electrical energy to achieve long-term flight. Traditional solar drones usually use single-sided solar cells arranged on the upper surface of the wing and ensure the wing strength through internal structures. With the development of double-sided solar cell technology, it has become possible to generate electricity by using the lower surface of the wing to receive ground-reflected light, which provides a new way to improve the endurance of solar drones.

[0003] However, the traditional wing structure design mainly considers structural strength, aerodynamic performance, and weight control, and does not fully consider the characteristics of double-sided power generation. Existing internal wing structures such as main beams, wing ribs, and support crossbars will seriously block the incident light on the lower surface, resulting in a significant reduction in the power generation efficiency of the back side of the double-sided solar cell. At the same time, the conventional lower skin material has insufficient light transmittance, and the uniform thickness distribution of the PMI foam substrate does not consider the optical reflection characteristics, making it impossible for the double-sided solar cell to effectively utilize the reflected light energy.

[0004] Currently, the industry lacks a systematic method for optimizing the double-sided generator wing structure of solar drones, and it is difficult to maximize the double-sided power generation efficiency while ensuring the structural strength, which seriously limits the endurance and practicality of solar drones. There is an urgent need for a technical solution that can synergistically optimize the wing structure and double-sided power generation efficiency. Summary of the Invention

[0005] In view of this, the present invention provides a double-sided generator wing structure for solar drones and an optimization method thereof, which can solve the technical problem that the double-sided generator wing structure of solar drones in the prior art fails to simultaneously consider structural strength and maximization of double-sided power generation efficiency.

[0006] The present invention is implemented as follows: In the first aspect of the present invention, a double-sided generator wing structure for solar drones is provided, including a wing, a double-sided solar cell assembly, and a lower skin. The inside of the wing is a hollow structure. The wing includes a leading edge, a main beam, wing ribs, support crossbars, and a trailing edge. A bonding area for the double-sided solar cell assembly is provided on the trailing edge. The double-sided solar cell assembly is fixedly installed between the trailing edge and the leading edge. The lower skin is made of a transparent material and is fixedly connected to the bottom of the leading edge, wing ribs, and trailing edge. The lower substrate of the double-sided solar cell assembly uses a PMI foam layer with light transmittance, so that the reflected light intensity irradiates the back side of the double-sided solar cell assembly, and the power generation efficiency of the double-sided solar cell assembly is improved through the power generation gain on the back side.

[0007] Among them, the number of the wing ribs is multiple groups, which are distributed at equal intervals and fixedly connected to the main beam, so as to cooperate with the main beam to ensure the structural strength of the wing and reduce the weight; the leading edge and the trailing edge are respectively arranged at the front and rear ends of the wing rib and fixedly connected to the wing rib; the supporting cross bar is fixedly connected to multiple groups of the wing ribs to maintain the shape of the double-sided solar cell module.

[0008] Among them, the wing ribs are provided with multiple groups of irregularly shaped wire holes for facilitating wiring; the wing is fixedly connected to the fuselage structure through the main beam; the wing ribs are provided with slots adapted to the main beam, and the wing ribs are fixedly connected to the main beam through the slots.

[0009] Among them, the lower skin has tensile resistance, the double-sided solar cell assembly is a double-sided solar cell panel, one end of the back side uses the light reflected by the ground and clouds to generate electricity, the double-sided solar cell assembly is bonded to the edge of the wing structure by epoxy glue, and the entire wing structure is a hollow design to facilitate the entry of sunlight.

[0010] The second aspect of the present invention provides an optimization method for the double-sided generator wing structure of a solar-powered unmanned aerial vehicle, comprising: establishing a basic power generation efficiency matrix of a double-sided solar cell assembly; using a space filling optimization algorithm to design the distribution spacing between the main beam and the wing ribs, and constructing a first structural change power generation efficiency matrix; adjusting the support cross bar layout to a fan-shaped distribution structure to form a second change power generation efficiency matrix; replacing the lower skin material with a high-transmittance polyester film to construct a first reverse change power generation efficiency matrix; changing the thickness gradient of the PMI foam substrate to establish a second reverse change power generation efficiency matrix; using five efficiency matrices for superposition analysis to construct an optimal change matrix; designing a new wing rib structure based on the optimal change matrix; preparing an optimized wing structure sample to test the double-sided power generation efficiency under different height simulation conditions; adjusting the PMI foam substrate thickness distribution according to the test data to form the final optimized design parameters.

[0011] Among them, establishing the basic power generation efficiency matrix of bifacial solar cell modules means dividing the wing surface into several regional grids, and each grid point records the power generation efficiency of the front surface and the power generation efficiency of the rear surface to form a two-dimensional data table for determining the initial power generation performance distribution.

[0012] Among them, the space filling optimization algorithm refers to a calculation method that determines the optimal seed point distribution so that the area divided by the Voronoi diagram meets the wing structure strength requirements and maximizes the light-transmitting area; the Voronoi diagram refers to a space division method that divides a plane or space into several areas, each area contains a seed point, and the distance from any point in the area to the seed point is less than the distance to any other seed point.

[0013] Among them, the fan-shaped distribution structure means that the support crossbars are radially arranged from the main beam to the trailing edge, and the density changes with the change of the trailing edge width, ensuring sufficient strength at the rear of the wing while maximizing the light transmission area; the high light transmittance polyester film refers to a modified polyethylene terephthalate material with a light transmittance exceeding 95% and having anti-ultraviolet performance; the PMI foam substrate thickness gradient means that from the wing root to the wing tip, the PMI foam substrate thickness changes according to a non-linear relationship, being thicker in the root area to enhance the structural strength and thinner in the wing tip area to reduce weight while ensuring the overall optimal light transmittance.

[0014] Among them, the design of the new wing rib structure includes adopting a lightweight honeycomb structure and optimizing the shape of the wire passing hole to an elliptical wire passing hole; the honeycomb structure refers to a lightweight design with a hexagonal grid arrangement inside the wing rib, reducing weight and increasing the light penetration area while ensuring the structural strength; the elliptical wire passing hole refers to an elliptical opening with the major axis parallel to the wingspan direction.

[0015] Among them, the optimization process uses a multi-objective optimization equation set, including a structural strength equation, a mass distribution equation, a light transmittance equation, and a power generation efficiency equation. By comprehensively considering the wing structural strength, mass distribution, light transmission performance, and power generation efficiency, the size parameters and positional relationships of each component of the wing structure are determined; the final optimized design parameters include the main beam cross-section size, wing rib distribution position, support crossbar layout, PMI foam substrate thickness distribution, and the light transmittance of the lower skin material, which are used to guide the manufacturing and assembly of the double-sided generator wing structure of the solar unmanned aerial vehicle.

[0016] The structure provided by the present invention designs a hollow structure for the wing through the main beam and wing ribs, and can realize double-sided power generation by combining the curved surface of the wing bending through the setting of double-sided solar cell modules. The bottom surface cooperates with the lower skin to utilize reflected light such as clouds for power generation, further improving the power generation efficiency. The method of the present invention realizes the collaborative optimization of the wing structure and the double-sided power generation efficiency by establishing multiple power generation efficiency matrices, combining the space filling optimization algorithm and the optical transmission and reflection model.

[0017] This method divides the wing structure space through the Voronoi diagram, optimizes the distribution of the main beam and wing ribs, adopts a fan-shaped distributed support crossbar, and combines the design of a high light transmittance polyester film and a PMI foam substrate thickness gradient, significantly improving the effective incident light intensity on the back of the double-sided solar cell module. The optimized honeycomb wing rib structure and elliptical wire passing hole design reduce weight and increase the light penetration area while ensuring the structural strength, effectively solving the problem of the traditional wing structure blocking the incident light on the back.

[0018] The present invention successfully solves the technical problem that it is difficult to balance the structural strength and the double-sided power generation efficiency of the double-sided generator wing structure of a solar unmanned aerial vehicle, realizes the maximization of the comprehensive power generation efficiency of the double-sided solar cell module on the premise of ensuring the safety of the wing structure, and provides an effective technical way to improve the endurance of the solar unmanned aerial vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a flowchart of the method provided by the present invention.

[0020] Figure 2 It is a schematic diagram of the double-sided generator wing structure of the solar unmanned aerial vehicle in Embodiment 2.

[0021] Figure 3 It is an internal schematic diagram of the double-sided generator wing structure of the solar unmanned aerial vehicle in Embodiment 2.

[0022] Figure 4 It is a schematic diagram of sunlight irradiation in Embodiment 2.

[0023] Figure 5 It is a diagram showing the relationship between the light transmittance of the wing structure and the rib distribution in Embodiment 2.

[0024] Figure 6 It is a diagram showing the relationship between the light intensity distribution and the power generation efficiency at different heights in Embodiment 2.

[0025] In the drawings, the list of components represented by each reference numeral is as follows:

[0026] 10, wing; 101, leading edge; 102, main beam; 103, rib; 104, support cross bar; 105, trailing edge; 11, double-sided solar cell module; 12, lower skin; 13, wire passing hole; 14, PMI foam layer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0028] In the first aspect of the present invention, a double-sided generator wing structure for a solar unmanned aerial vehicle is provided. This structure mainly consists of a wing, a double-sided solar cell module, and a lower skin. The wing adopts a hollow internal structure design, including key components such as a leading edge, a main beam, wing ribs, support crossbars, and a trailing edge. Among them, the main beam serves as the core framework of the wing, ensuring the strength and stiffness of the entire wing, and is fixedly connected to the fuselage structure; the number of wing ribs is multiple groups, evenly distributed and fixedly connected to the main beam, used to cooperate with the main beam to ensure the wing structure strength and reduce weight. At the same time, multiple groups of irregularly shaped wire passing holes are opened on the wing ribs to facilitate circuit wiring. A slot adapted to the main beam is also opened on the wing ribs, and the wing ribs are fixedly connected to the main beam through the slots; the leading edge and the trailing edge are respectively arranged at the front and rear ends of the wing ribs and are fixedly connected to the wing ribs. The leading edge ensures the aerodynamic effect while guaranteeing strength and stiffness, and the trailing edge provides a certain strength and provides an adhesive area for the solar cell module; the support crossbars are fixedly connected to multiple groups of wing ribs to perform a conformal design for the double-sided solar cell module.

[0029] The double-sided solar cell module is a double-sided solar cell panel, fixedly installed between the trailing edge and the leading edge, and adhesively bonded to the edge of the wing structure through epoxy glue. One end of its back can generate electricity by using the light reflected by the ground, clouds, etc. The lower substrate of this double-sided solar cell module adopts a PMI foam layer with good light transmittance, which is used to cooperate with the lower skin to make the reflected light strongly irradiate the back of the double-sided solar cell module, improving the power generation efficiency of the double-sided solar cell module. By using a PMI foam substrate with better light transmittance and adding the strong irradiation of the reflected light to the back of the battery, a backside power generation gain can be obtained, which can improve the power generation efficiency of the solar cell to a certain extent, enabling the double-sided power generation of the solar unmanned aerial vehicle to be implemented.

[0030] The lower skin adopts a transparent material and a film with tensile properties, and is fixedly connected to the bottom of the leading edge, wing ribs, and trailing edge. The transparent material design is conducive to the penetration of sunlight, and the tensile properties ensure the structural stability during flight. The entire wing structure is a hollow design, which can allow sunlight to enter better. The wing ribs are hollowed out on the basis of ensuring strength and stiffness. On the one hand, it is to reduce weight, and on the other hand, it is for the convenience of wiring for the whole machine.

[0031] It can be seen from the comparison of experimental data that this double-sided generator wing structure of a solar drone can significantly improve the power generation efficiency. The power generation efficiency of Component 1 with a film without a substrate on the back reaches 25.36%, the power generation efficiency of Component 2 with a PMI foam substrate with better light transmittance on the back is 24.94%, and the power generation efficiency of Component 3 with a PMI foam substrate without light transmittance on the back is only 23.92%. The present invention lays the double-sided power generation flexible solar cell module conformally on the unique structure of the drone. The lower surface absorbs energy through the solar reflected light of the clouds at high altitude. The power generation gain on the back can improve the power generation efficiency of the solar drone, and thus improve the flight altitude ability of the solar drone. Through a unique wing mechanism and process method, the present invention realizes the effect of sunlight reflecting onto the back of the solar cell module, and the back gain improves the power generation efficiency of the solar cell.

[0032] The second aspect of the present invention provides an optimization method for the double-sided generator wing structure of a solar drone, including the following steps:

[0033] S01. Establish a basic power generation efficiency matrix of the double-sided solar cell module. By measuring the front surface power generation efficiency and the back surface power generation efficiency of the double-sided solar cell module at different positions under standard illumination conditions, an initial data set is formed;

[0034] S02. Use a space-filling optimization algorithm to design the distribution spacing of the main beam and the wing ribs, construct a first structural change power generation efficiency matrix, and divide the wing structure space through a Voronoi diagram to make the wing rib distribution meet the strength requirements while maximizing the light transmittance performance;

[0035] S03. Adjust the layout of the support cross bars to a fan-shaped distribution structure to form a second change power generation efficiency matrix, and evaluate the influence of the support cross bars on the power generation efficiency of the double-sided solar cell module;

[0036] S04. Replace the lower skin material with a high light transmittance polyester film, measure the reflected light intensity distribution, and construct a first reverse change power generation efficiency matrix;

[0037] S05. Change the thickness gradient of the PMI foam substrate, establish a second reverse change power generation efficiency matrix, and use an optical transmission and reflection model to analyze the relationship between the thickness and the conversion of reflected light energy;

[0038] S06. Use the basic power generation efficiency matrix, the first structural change power generation efficiency matrix, the second change power generation efficiency matrix, the first reverse change power generation efficiency matrix, and the second reverse change power generation efficiency matrix for superposition analysis, construct an optimal change matrix, and determine the size parameters and positional relationships of the various components of the wing structure through a multi-objective optimization equation set;

[0039] S07. Design a new wing rib structure based on the optimal change matrix, adopt a lightweight honeycomb structure and optimize the shape of the wire holes to elliptical wire holes;

[0040] S08. Prepare optimized wing structure samples and test the bifacial power generation efficiency of bifacial solar cell modules under conditions of simulated sunlight and cloud reflection at different altitudes;

[0041] S09, adjusting the thickness distribution of the PMI foam substrate on the back side of the bifacial solar cell module according to the test data to form the final optimized design parameters;

[0042] The basic power generation efficiency matrix refers to dividing the wing surface into several regional grids, and each grid point records the power generation efficiency of the front surface and the power generation efficiency of the rear surface to form a two-dimensional data table, which is used to determine the initial power generation performance distribution status;

[0043] The first structural change power generation efficiency matrix refers to a two-dimensional data table formed by the power generation efficiency of the front surface and the power generation efficiency of the rear surface corresponding to each grid point on the wing surface after adjusting the distribution of the main beam and the ribs through the space filling optimization algorithm;

[0044] The second changed power generation efficiency matrix refers to a two-dimensional data table formed by the power generation efficiency of the front surface and the power generation efficiency of the rear surface corresponding to each grid point on the wing surface after adjusting the support horizontal bars to a fan-shaped distribution structure;

[0045] The first reverse change power generation efficiency matrix refers to a two-dimensional data table formed by the power generation efficiency of the front surface and the power generation efficiency of the rear surface corresponding to each grid point on the wing surface after the lower skin material is replaced with a high-transmittance polyester film;

[0046] The second reverse change power generation efficiency matrix refers to a two-dimensional data table formed by the front surface power generation efficiency and the rear surface power generation efficiency of each grid point on the wing surface after changing the thickness gradient of the PMI foam substrate;

[0047] The optimal change matrix is calculated by weighted average of five efficiency matrices, and the weight coefficient is determined according to the influence of each change on the power generation efficiency. The optimal change matrix includes the relationship between the structural parameters of each part of the wing and the corresponding power generation efficiency;

[0048] The Voronoi diagram refers to a space partitioning method that divides a plane or space into several regions, each region contains a seed point, and the distance from any point in the region to the seed point is less than the distance to any other seed point;

[0049] Among them, the space filling optimization algorithm refers to a calculation method that determines the optimal seed point distribution so that the area divided by the Voronoi diagram meets the wing structure strength requirements and maximizes the light transmission area;

[0050] Among them, the fan-shaped distribution structure means that the support crossbars are radially arranged from the main beam to the trailing edge, and the density changes with the width of the trailing edge, ensuring sufficient strength at the rear of the wing while maximizing the light transmission area;

[0051] Among them, the high light transmittance polyester film refers to a modified polyethylene terephthalate material with a light transmittance exceeding 95% and having anti-ultraviolet properties, and its light transmittance is increased by more than 15% compared with ordinary transparent materials;

[0052] Among them, the PMI foam substrate thickness gradient means that from the wing root to the wing tip, the thickness of the PMI foam substrate changes according to a non-linear relationship, with a thicker root area to enhance the structural strength and a thinner wing tip area to reduce weight, while ensuring the optimal overall light transmittance;

[0053] Among them, the optical transmission and reflection model refers to a mathematical model of light propagation established based on the Fresnel formula and the Beer-Lambert law, which is used to calculate the influence of PMI foam substrates with different thicknesses on the solar light transmittance and reflectance;

[0054] Among them, the multi-objective optimization equation set includes a structural strength equation, a mass distribution equation, a light transmittance equation, and a power generation efficiency equation;

[0055] Among them, the structural strength equation is used to calculate the stress conditions and deformation degrees of the wing under different flight states. The inputs include the elastic modulus of the wing structure material, the moment of inertia of the main beam cross-section, the rib distribution density, the external load distribution, and the material yield strength, and the outputs are the stress distribution and deformation amount of each part of the wing;

[0056] Among them, the mass distribution equation is used to calculate the mass density of each part of the wing and the position of the overall center of gravity. The inputs include the material density of each structural member, the size parameters of the structural members, the spatial distribution of the structural members, the surface density of the double-sided solar cell module, and the mass of the connecting material, and the outputs are the mass distribution of the wing and the total mass;

[0057] Among them, the light transmittance equation is used to calculate the light intensity distribution of sunlight penetrating the lower surface of the wing and reaching the back of the double-sided solar cell module. The inputs include the light transmittance of the lower skin, the light transmittance of the PMI foam substrate, the shielding rate of the internal structure of the wing, the incident light angle, and the light source intensity, and the output is the effective light intensity reaching the back of the double-sided solar cell module;

[0058] Among them, the power generation efficiency equation is used to calculate the total power generation efficiency of the double-sided solar cell module under given conditions. The inputs include the front incident light intensity, the back incident light intensity, the temperature of the double-sided solar cell module, the front surface efficiency coefficient of the double-sided solar cell module, and the back surface efficiency coefficient of the double-sided solar cell module, and the output is the comprehensive power generation efficiency of the double-sided solar cell module;

[0059] Among them, the comprehensive power generation efficiency refers to the weighted sum of the power generation efficiency of the front surface and the rear surface of the bifacial solar cell module, and the weight is determined by the ratio of the incident light intensity on the front surface to the incident light intensity on the rear surface;

[0060] Among them, the honeycomb structure refers to a lightweight design with a hexagonal grid arrangement inside the wing rib, which reduces the weight and increases the light penetration area while ensuring the structural strength;

[0061] Among them, the oval wire-through hole refers to an oval opening with the major axis parallel to the wingspan direction. Compared with the circular wire-through hole, it reduces the stress concentration phenomenon by 35% and increases the wire-through area by 15% at the same time;

[0062] Among them, the different altitude simulation conditions refer to simulating direct sunlight and cloud-reflected light at high altitudes through special optical devices in the ground test environment. The test altitudes include four gradients of 1000 meters, 3000 meters, 5000 meters, and 7000 meters;

[0063] Among them, the final optimized design parameters include the main beam cross-sectional size, the wing rib distribution position, the support cross-bar layout, the PMI foam substrate thickness distribution, and the light transmittance of the lower skin material, which are used to guide the manufacturing and assembly of the bifacial generator wing structure of the solar UAV.

[0064] The specific implementation manners of the above steps are described in detail below. The specific implementation manner of step S01 is to first construct a standard test platform, which includes an artificial light source system simulating the standard AM1.5 illumination and a precision optoelectronic conversion efficiency measurement device. By setting a 10×10 grid dot matrix on the wing surface, samples of bifacial solar cell modules with a standard size (100mm×100mm) are placed at each grid point for testing. During the test, first measure the power generation efficiency of the front surface under the standard illumination (1000W / m 2 ), and the value is usually between 22% and 26%; then flip the sample to measure the power generation efficiency of the rear surface under the same conditions, and the value is usually between 18% and 22%. Enter the data of all test points into the computer system, and use the bilinear interpolation algorithm to estimate the efficiency values at non-test point positions, so as to form a complete basic power generation efficiency matrix. The purpose of this step is to obtain the reference performance data of the bifacial solar cell module under ideal conditions and provide a reference standard for subsequent optimization. During the test process, the environmental temperature is controlled at 25±2°C, and the relative humidity is controlled at 45%±5% to eliminate the influence of environmental factors on the test results.

[0065] The specific implementation of step S02 is to use the Voronoi diagram algorithm in computational geometry for the spatial optimization of the wing structure. First, based on the aerodynamic shape and strength requirements of the wing, the overall wing dimensions and the position of the main beam are determined. Then, by generating an initial set of seed points (usually 20 - 30 points), an iterative optimization method is used to adjust the positions of the seed points. In each iteration, the Voronoi diagram generated by the current seed points is calculated, and the structural strength and light transmission performance are evaluated. The strength evaluation uses the finite element analysis method, and the light transmission performance is obtained by calculating the proportion of the non-structural area in the total area. The simulated annealing algorithm is used to continuously adjust the positions of the seed points. When the structural strength meets the minimum safety factor of 1.5 and the light transmittance is not less than 75%, the final distribution of the seed points is determined. Based on the final Voronoi diagram, the exact positions and shapes of the wing ribs are determined, and the connection method between the main beam and the wing ribs adopts a slot structure to improve integrity. The purpose of this step is to maximize the sunlight transmittance on the premise of ensuring the structural strength of the wing, creating conditions for double-sided power generation.

[0066] The specific implementation of step S03 is to design a fan-shaped distribution structure of the support crossbars according to the wing rib distribution determined in the second step. First, the starting point (located on the main beam) and the ending point (located on the trailing edge) of the support crossbars are determined. Using the radial basis function interpolation algorithm, a mapping relationship is established between the spatial distribution density of the support crossbars and the trailing edge width, so that the spacing between the support crossbars at the wing root is smaller (usually 50 mm - 80 mm), and the spacing between the support crossbars at the wing tip is larger (usually 100 mm - 150 mm). The cross-section of the support crossbars is designed as an I-beam to reduce weight while ensuring strength. The material of the support crossbars is selected as carbon fiber composite material, with an elastic modulus not less than 230 GPa and a density not higher than 1.6 g / cm 3 . After completing the layout design of the support crossbars, the double-sided power generation efficiency of the solar cell modules is measured again at each grid point position, the data is recorded, and the second modified power generation efficiency matrix is constructed. The purpose of this step is to ensure that the double-sided solar cell modules obtain sufficient mechanical support and at the same time form a scientific fan-shaped distribution structure to optimize the sunlight transmittance.

[0067] The specific implementation of step S04 is to select and test the lower skin material. First, high light transmittance polyester film materials on the market are screened, requiring a light transmittance exceeding 95% and excellent anti-ultraviolet aging performance (under ultraviolet irradiation intensity of 0.68 W / m 2Under the condition that (the light transmittance decreases by no more than 3% after 1000 hours of testing), select 3 to 5 candidate materials and fabricate samples of standard size (200mm×200mm), and measure their light transmittance under standard lighting conditions. Select the material with the highest light transmittance and whose mechanical properties meet the requirements (tensile strength not less than 120MPa, elongation at break not less than 15%) as the lower skin. Apply the selected lower skin material to the wing structure, measure the power generation efficiency of the bifacial solar cell module at each grid point, and construct the first reverse change power generation efficiency matrix. The purpose of this step is to increase the light intensity reaching the back of the solar cell module by passing sunlight through the lower surface of the wing with a high light transmittance lower skin material, thereby improving the back power generation efficiency.

[0068] The specific implementation of step S05 is to design and optimize the thickness distribution of the PMI foam substrate. First, establish an optical transmission and reflection model, which is based on the Fresnel formula and the Beer-Lambert law and is used to predict the transmission and reflection characteristics of light by PMI foam with different thicknesses. Input the refractive index of the PMI foam (usually 1.05 - 1.15), the absorption coefficient of sunlight with different wavelengths, the incident light angle distribution, and the thickness parameters of the PMI foam into the model. According to the calculation results of the model, design the thickness gradient distribution of the PMI foam substrate so that the thickness of the PMI foam at the wing root is 8 - 10mm (ensuring sufficient strength), and the thickness at the wing tip is 3 - 5mm (reducing weight). The thickness change is smoothly transitioned using a cubic spline function to avoid stress concentration caused by sudden changes. Apply the designed PMI foam substrate to the wing structure, measure the power generation efficiency of the bifacial solar cell module at each grid point, and construct the second reverse change power generation efficiency matrix. Through this step, utilize the light transmittance and reflection characteristics of the PMI foam to optimize the light intensity distribution received on the back, and improve the back power generation gain.

[0069] The specific implementation of step S06 is to conduct comprehensive optimization analysis based on the power generation efficiency matrix obtained from the previous five steps. First, establish a multi-objective optimization equation set, including a structural strength equation, a mass distribution equation, a light transmittance equation, and a power generation efficiency equation. In the structural strength equation, input the elastic modulus of the wing structure material, the cross-sectional moment of inertia of the main beam, the distribution density of the wing ribs, the external load distribution during flight, and the yield strength of the material, and calculate the stress distribution and deformation of each part of the wing through finite element analysis. In the mass distribution equation, input the material density, size parameters, spatial distribution of each structural member, the surface density of the double-sided solar cell module, and the mass of the connecting material, and calculate the mass distribution and total mass of the wing. In the light transmittance equation, input the light transmittance of the lower skin, the light transmittance of the PMI foam substrate, the shielding rate of the internal wing structure, the incident angle of sunlight, and the light source intensity, and calculate the effective light intensity reaching the back of the double-sided solar cell module. In the power generation efficiency equation, input the front incident light intensity, the back incident light intensity, the temperature of the double-sided solar cell module, the front surface efficiency coefficient, and the back surface efficiency coefficient, and calculate the comprehensive power generation efficiency. Use the genetic algorithm to solve the multi-objective optimization problem, set the population size to 100, the number of evolutionary generations to 50, the crossover probability to 0.8, and the mutation probability to 0.1. Find the Pareto optimal solution set through algorithm iteration, select the solution with the best comprehensive performance as the final design scheme, and construct the optimal change matrix. The purpose of this step is to find the best balance among multiple objective functions and obtain the optimal design parameters of the wing structure.

[0070] The specific implementation of step S07 is to conduct a detailed design of the wing rib structure according to the calculation results of the optimal change matrix. Adopt the parametric design method, design the internal structure of the wing rib as a honeycomb shape, and the unit size gradually increases from the wing root to the wing tip. The unit size at the wing root is 15 - 20 mm, and the unit size at the wing tip is 25 - 30 mm. The honeycomb wall thickness gradually decreases from the wing root to the wing tip. The wall thickness at the wing root is 1.2 - 1.5 mm, and the wall thickness at the wing tip is 0.8 - 1.0 mm. Further optimize the honeycomb structure through the topology optimization algorithm, appropriately increase the structural density in the stress concentration area, and reduce the material usage in the low-stress area. The wire passing hole adopts an oval design, the major axis is parallel to the wing span direction, the major axis length is 20 - 25 mm, and the minor axis length is 10 - 12 mm. Ensure that the stress concentration coefficient around the wire passing hole does not exceed 1.5 through finite element analysis. The wing rib material is selected as aerospace-grade aluminum alloy or carbon fiber composite material, with a density not exceeding 2.7 g / cm 3 , and the yield strength is not less than 400 MPa. The purpose of this step is to achieve the lightweight and high light transmittance of the wing rib structure, while ensuring sufficient structural strength and stiffness, creating favorable conditions for double-sided power generation.

[0071] The specific implementation of step S08 is to fabricate an optimized wing structure sample and conduct test verification. First, fabricate structural components such as main beams, wing ribs, and support crossbars according to the design parameters, and use precision machining and composite material forming processes to ensure dimensional accuracy and surface quality. Assemble the structural components at the designed positions, install a high light transmittance polyester film as the lower skin, lay a PMI foam substrate with an optimized thickness distribution, and finally install a double-sided solar cell module. Then, place the sample in a special optical test device that can simulate direct sunlight and cloud-reflected light conditions at different altitudes (1000 m, 3000 m, 5000 m, 7000 m). Measure the front surface power generation efficiency and back surface power generation efficiency of the double-sided solar cell module under each simulated condition, and calculate the comprehensive power generation efficiency. Record the light intensity, incident angle, environmental temperature, and power generation efficiency data under each test condition to establish a database for subsequent analysis. The purpose of this step is to verify the effectiveness of the optimized design in a real environment and provide measured data support for the final design.

[0072] The specific implementation of step S09 is to make final adjustments and optimizations to the design based on the test results. First, analyze the test data under different altitude simulation conditions, and establish a relationship model between power generation efficiency and altitude and light conditions. Use the multiple regression analysis method to find the key factors affecting power generation efficiency and their weights. According to the analysis results, focus on making fine adjustments to the thickness distribution of the PMI foam substrate. The adjustment strategy is based on the optimal control theory, and the objective function is set to maximize the comprehensive power generation efficiency. Usually, the adjustment range of the PMI foam thickness is within ±2 mm. The adjustment process uses the gradient descent method, with a step size set to 0.2 mm and the number of iterations not exceeding 20 times. After the adjustment is completed, obtain the final thickness distribution parameters of the PMI foam substrate. Combine all design parameters to form a complete design document, including the main beam cross-sectional dimensions, wing rib distribution positions, support crossbar layouts, PMI foam substrate thickness distributions, and lower skin material parameters, etc. The purpose of this step is to finely optimize the design based on the measured data, so that the double-sided generator wing structure of the solar UAV reaches the best performance state, and ultimately improve the flight altitude and endurance of the solar UAV.

[0073] The following details the mathematical models or calculation processes involved in the present invention.

[0074]

[0075] In the formula, E base is the front surface basic power generation efficiency matrix; is the back surface basic power generation efficiency matrix; is the front surface power generation efficiency of the grid point in the i-th row and j-th column, and its value range is 22% - 26%; is the back surface power generation efficiency of the grid point in the i-th row and j-th column, and its value range is 18% - 22%.

[0076] For the efficiency values at non-test point positions, the bilinear interpolation algorithm is used for calculation:

[0077]

[0078] In the formula, e(x, y) is the interpolation efficiency at coordinates (x, y); (x1, y1), (x1, y2), (x2, y1), (x2, y2) are the coordinates of the four nearest test points surrounding (x, y); e 1，1 , e 1，2 , e 2，1 , e 2，2 are the efficiency values of the corresponding test points.

[0079] The construction of the Voronoi diagram in the space filling optimization algorithm can be expressed as:

[0080]

[0081] In the formula, V i is the Voronoi region of the i-th seed point p i ; d(x, p i ) is the Euclidean distance from point x to the seed point p i , that is where and are the x coordinate and y coordinate of the seed point p i respectively; represents the two-dimensional Euclidean space.

[0082] The distribution of seed points is optimized by the simulated annealing algorithm, and the objective function is:

[0083] F(P) = w1·S(P) + w2·T(P);

[0084] In the formula, F(P) is the optimization objective function; P = {p1, p2,..., p n} is the set of seed points; S(P) is the structural strength evaluation function, which is the reciprocal of the safety factor calculated by finite element analysis; T(P) is the light transmittance evaluation function, which is calculated as the ratio of the non-structural area to the total area; w1 and w2 are weight coefficients, satisfying w1 + w2 = 1, and generally w1 = 0.6 and w2 = 0.4 are taken.

[0085] Calculation of the acceptance probability of the simulated annealing algorithm:

[0086]

[0087] In the formula, P accept is the probability of accepting the new solution; P new is the newly generated set of seed points; P currentis the current set of seed points; T is the current temperature parameter, whose initial value is usually set to 100, and is updated according to the cooling strategy of T new = 0.95·T current .

[0088] For the support crossbars with a fan-shaped distribution, the mapping relationship between their spatial distribution density and the trailing-edge width can be expressed as:

[0089]

[0090] In the formula, d(r) is the spacing of the support crossbars at the spanwise position r; d0 is the minimum spacing at the wing root, with a value range of 50 mm to 80 mm; d1 is the maximum spacing at the wing tip, with a value range of 100 mm to 150 mm; w(r) is the trailing-edge width at the spanwise position r; w min and w max are the minimum and maximum widths of the trailing edge respectively; r is the normalized distance from the wing root to the wing tip, with a range of [0, 1].

[0091] Using the radial basis function interpolation algorithm, it can be expressed as:

[0092]

[0093] In the formula, f(x) is the interpolation function; λ i is the weight coefficient; φ is the radial basis function, usually the Gaussian function is selected where ε is the shape parameter, usually with a value of 0.01 to 0.1; ||x - x i || is the Euclidean distance from point x to the known point x i ; n is the number of known points.

[0094] For the optical transmission and reflection model, based on the Fresnel formula and the Beer-Lambert law, the transmittance is calculated as:

[0095] T = (1 - R)·e -α·d ;

[0096] In the formula, T is the transmittance; R is the reflectance, calculated by the Fresnel formula: where n1 and n2 are the refractive indices of air and PMI foam respectively, θ i is the incident angle, θ t is the refraction angle, calculated by Snell's law n1sinθ i = n2sinθ t ; α is the absorption coefficient, related to the material and the wavelength of light. For PMI foam, the empirical formula can be used, where α0 is the absorption coefficient at the reference wavelength λ0, k is the material characteristic parameter; d is the material thickness.

[0097] The multi-objective optimization equations in step S06 can be expressed as follows:

[0098] 1. Structural strength equation:

[0099]

[0100] In the formula, σ max is the maximum stress; M max is the maximum bending moment; y max is the maximum distance from the section edge to the neutral axis; I x is the moment of inertia of the cross-section; σ yield is the material yield strength; SF is the safety factor, and the minimum value is 1.5.

[0101] For the finite element analysis of the wing structure, the stiffness matrix equation is:

[0102] [K]{u} = {F};

[0103] In the formula, [K] is the stiffness matrix; {u} is the nodal displacement vector; {F} is the nodal force vector.

[0104] 2. Mass distribution equation:

[0105]

[0106] In the formula, m total is the total mass of the wing; n s is the number of structural members; ρ i is the material density of the i-th structural member; V i is the volume of the i-th structural member; ρ cell is the surface density of the bifacial solar cell module; A cell is the area of the bifacial solar cell module; m conn is the mass of the connecting material.

[0107] Calculation of the center of gravity position:

[0108]

[0109] In the formula, is the wing center of gravity position vector; m i is the mass of the i-th structural member; is the center of gravity position vector of the i-th structural member; is the center of gravity position vector of the bifacial solar cell module; is the center of gravity position vector of the connecting material.

[0110] 3. Transmittance equation:

[0111] Iback = I0·T skin ·P PMI ·(1 - B struct );

[0112] In the formula, I back is the effective light intensity reaching the back of the bifacial solar cell module; I0 is the incident light intensity; T skin is the light transmittance of the lower skin, with a value greater than 95%; T PMI is the light transmittance of the PMI foam substrate, the value of which is determined by the thickness and calculated through the previous transmittance formula; B struct is the shielding rate of the internal structure of the wing, defined as the ratio of the projected area of the structural members in the wing plane to the total area of the wing.

[0113] 4. Power generation efficiency equation:

[0114]

[0115] In the formula, η total is the comprehensive power generation efficiency of the bifacial solar cell module; I front is the incident light intensity on the front surface; I back is the incident light intensity on the back surface; η front is the front surface efficiency coefficient, with a value range of 22% - 26%; η back is the back surface efficiency coefficient, with a value range of 18% - 22%; β is the temperature coefficient, usually with a value of 0.004 - 0.005 / °C; T is the operating temperature of the bifacial solar cell module; T ref is the reference temperature, usually 25°C.

[0116] The fitness function of the genetic algorithm in multi-objective optimization can be expressed as:

[0117] F(X) = w1·f1(X) + w2·f2(X) + w3·f3(X) + w4·f4(X);

[0118] In the formula, F(X) is the total fitness function; X is the design variable vector, including main beam section parameters, rib distribution positions, support cross-bar layouts, PMI foam substrate thickness distributions, and lower skin material parameters, etc.; f1(X) is the structural strength objective function, usually defined as the ratio of the maximum stress to the allowable stress; f2(X) is the mass objective function, usually defined as the ratio of the total mass to the target mass; f3(X) is the light transmittance objective function, defined as 1 minus the ratio of the effective light intensity reaching the back surface to the incident light intensity on the front surface; f4(X) is the power generation efficiency objective function, defined as the ratio of the comprehensive power generation efficiency to the target efficiency; w1, w2, w3, w4 are weight coefficients, satisfying w1 + w2 + w3 + w4 = 1, and different values can be taken according to different design focuses.

[0119] The design of the PMI foam substrate thickness gradient uses a cubic spline function:

[0120] d(r) = a0 + a1r + a2r 2 + a3r 3 ;

[0121] where d(r) is the thickness of the PMI foam substrate at the spanwise position r; a0, a1, a2, and a3 are undetermined coefficients calculated from the boundary conditions; and r is the normalized distance from the wing root to the wing tip, ranging from [0, 1].

[0122] The boundary conditions are: d(0) = d root , d(1) = d tip , d′(0) = s root , d′(1) = s tip , where d root is the PMI foam thickness at the wing root, with a value of 8 - 10 mm; d tip is the PMI foam thickness at the wing tip, with a value of 3 - 5 mm; s root and s tip are the thickness change rates at the wing root and wing tip, respectively.

[0123] Using the boundary conditions, the coefficients can be solved:

[0124] a0 = d root ;

[0125] a1 = s root ;

[0126] a2 = 3(d tip - d root ) - 2s root - s tip ;

[0127] a3 = 2(d root - d tip ) + s root + s tip ;

[0128] The honeycomb structure unit size distribution in step S07 can be expressed as:

[0129] L(r) = L root + (L tip - L root )·r;

[0130] where L(r) is the honeycomb cell size at the spanwise position r; L root is the cell size at the wing root, with a value of 15 - 20 mm; L tip$d$ is the unit size at the wing tip, with a value range of 25 - 30 mm; $r$ is the normalized distance from the wing root to the wing tip, with a range of [0, 1].

[0131] The honeycomb wall thickness distribution can be expressed as:

[0132]

[0133] In the formula, $t(r)$ is the honeycomb wall thickness at the spanwise position $r$; $t$ root is the wall thickness at the wing root, with a value range of 1.2 - 1.5 mm; $t$ tip is the wall thickness at the wing tip, with a value range of 0.8 - 1.0 mm; $r$ is the normalized distance from the wing root to the wing tip, with a range of [0, 1].

[0134] In step S09, the gradient descent method is used to finally optimize the PMI foam thickness, and the iteration formula is:

[0135]

[0136] In the formula, is the PMI foam thickness at the $i$-th position in the $k$-th iteration; is the PMI foam thickness at the $i$-th position in the $(k + 1)$-th iteration; $\alpha$ is the learning rate, usually with a value range of 0.05 - 0.1; is the partial derivative of the comprehensive power generation efficiency with respect to the PMI foam thickness at the $i$-th position, approximately calculated by the finite difference method: where $\Delta d$ is a small perturbation, usually with a value of 0.1 mm.

[0137] The above mathematical expressions and calculation processes constitute the theoretical basis of the wing structure optimization method for a solar unmanned aerial vehicle's double-sided generator. These equations consider multiple factors such as structural strength, mass distribution, optical properties, and power generation efficiency. Through accurate mathematical models and optimization algorithms, the optimal design of the wing structure is finally achieved, improving the comprehensive power generation efficiency of the double-sided solar cell module. Among them, the exponential relationship is adopted in the light transmittance equation based on the Beer - Lambert law, which describes the attenuation characteristics of light in a homogeneous medium; the temperature influence is considered in the power generation efficiency equation because the efficiency of solar cells decreases linearly with the increase in temperature; the distribution of the honeycomb structure size and wall thickness adopts a linear or non - linear relationship to achieve a reasonable distribution of mass while meeting the strength requirements. Through these carefully designed mathematical models, the performance characteristics of each component of the wing structure can be accurately described, providing a theoretical basis for the optimization design.

[0138] Specifically, the principle of the present invention is: The technical principle of the present invention is based on the multi - disciplinary integration of optics, structural mechanics, and energy conversion. By establishing a power generation efficiency matrix and a multi - objective optimization equation set, the collaborative optimization of the wing structure and the double - sided power generation efficiency is realized.

[0139] First, the present invention establishes a basic power generation efficiency matrix. By measuring the power generation efficiency of the front and back surfaces of a bifacial solar cell module through grid-based measurement, an initial data set is formed, providing a benchmark for subsequent structural optimization. Designing the distribution of main beams and wing ribs using a space-filling optimization algorithm is the core of the present invention. This algorithm is based on the principle of Voronoi diagrams, optimally dividing the wing structure space to ensure that the wing rib distribution meets the strength requirements while maximizing the light transmission performance. The design of the fan-shaped support crossbars conforms to the load distribution characteristics of the wing trailing edge, ensuring both structural strength and reducing the occlusion of incident light on the back surface.

[0140] In terms of material selection and layout, the present invention uses a high light transmittance polyester film to replace the traditional lower skin material, with the light transmittance increased by more than 15%; and through the design of the thickness gradient of the non-linear PMI foam substrate, the conversion of reflected light energy is optimized based on the optical transmission and reflection model. This model combines the Fresnel formula and the Beer-Lambert law to accurately calculate the influence of PMI foam substrates with different thicknesses on the solar light transmittance and reflectance, achieving the optimal utilization of reflected light energy.

[0141] The present invention comprehensively balances the structural strength, mass distribution, light transmittance, and power generation efficiency through a multi-objective optimization equation set to ensure the synergistic effect among various optimization parameters. The honeycomb wing rib structure and the elliptical through-hole design further reduce the weight, increase the light penetration area, and at the same time reduce the stress concentration phenomenon. By simulating tests under different heights of solar illumination and cloud reflection conditions, the thickness distribution of the PMI foam substrate is optimized to form the final design parameters, achieving a closed-loop verification from theoretical optimization to practical application.

[0142] A specific embodiment 1 of the present invention is provided below, and the specific implementation manners of each step in this embodiment 1 are described in detail as follows.

[0143] The specific implementation manner of step S01 is to first construct a standard test platform, including an artificial light source system simulating standard AM1.5 illumination and a precision optoelectronic conversion efficiency measurement device. Set a 10×10 grid lattice on the wing surface, and place a sample of a bifacial solar cell module with a standard size of 100mm×100mm at each grid point for testing. During the test, first measure the power generation efficiency of the front surface under standard illumination of 1000W / m 2 ², and the value is usually between 22% and 26%; then flip the sample to measure the power generation efficiency of the back surface under the same conditions, and the value is usually between 18% and 22%. Enter the data of all test points into the computer system to form a basic power generation efficiency matrix:

[0144]

[0145] In the formula, E baseis the front surface basic power generation efficiency matrix; is the back surface basic power generation efficiency matrix; is the front surface power generation efficiency of the grid point in the i-th row and j-th column, with a range of 22% to 26%; is the back surface power generation efficiency of the grid point in the i-th row and j-th column, with a range of 18% to 22%. For the efficiency values at non-test point positions, the bilinear interpolation algorithm is used for calculation:

[0146]

[0147] In the formula, e(x, y) is the interpolation efficiency at the coordinate (x, y); (x1, y1), (x1, y2), (x2, y1), (x2, y2) are the coordinates of the four nearest test points surrounding (x, y); e 1，1 , e 1，2 , e 2，1 , e 2，2 are the efficiency values of the corresponding test points. During the test process, the ambient temperature is controlled at 25±2°C, and the relative humidity is controlled at 45%±5% to eliminate the influence of environmental factors on the test results. The purpose of this step is to obtain the benchmark performance data of the bifacial solar cell module under ideal conditions and provide a reference standard for subsequent optimization.

[0148] The specific implementation method of step S02 is to use the Voronoi diagram algorithm in computational geometry for the spatial optimization of the wing structure. First, based on the aerodynamic shape and strength requirements of the wing, the overall wing size and the position of the main beam are determined. Then, by generating an initial set of seed points (usually 20 to 30 points), the positions of the seed points are adjusted using an iterative optimization method. The construction of the Voronoi diagram can be expressed as:

[0149] : d(x, p i ) ≤ d(x, p j ) for all j≠i};

[0150] In the formula, V i is the Voronoi region of the i-th seed point p i ; d(x, p i ) is the Euclidean distance from point x to the seed point p i , that is where and are the x coordinate and y coordinate of the seed point p i respectively; represents the two-dimensional Euclidean space. In each iteration, the structural strength and light transmission performance are evaluated. The strength evaluation uses the finite element analysis method, and the light transmission performance is obtained by calculating the proportion of the non-structural area in the total area. The simulated annealing algorithm is used to continuously adjust the positions of the seed points, and the objective function is:

[0151] F(P) = w1·S(P) + w2·T(P);

[0152] Wherein, F(P) is the optimization objective function; P = {p1, p2,..., p n} is the set of seed points; S(P) is the structural strength evaluation function, which is the reciprocal of the safety factor calculated by finite element analysis; T(P) is the light transmittance evaluation function, which is calculated as the ratio of the non-structural area to the total area; w1 and w2 are weight coefficients, satisfying w1 + w2 = 1, and generally w1 = 0.6 and w2 = 0.4. The acceptance probability calculation of the simulated annealing algorithm:

[0153]

[0154] Wherein, P accept is the probability of accepting the new solution; P new is the newly generated set of seed points; P current is the current set of seed points; T is the current temperature parameter, and the initial value is usually set to 100, and it is updated according to the cooling strategy of T new = 0.95·T current When the structural strength meets the minimum safety factor of 1.5 and the light transmittance is not less than 75%, the final seed point distribution is determined. Based on the final Voronoi diagram, the exact position and shape of the wing ribs are determined, and the connection method between the main beam and the wing ribs adopts a slot structure to improve the integrity. The purpose of this step is to maximize the sunlight transmittance on the premise of ensuring the structural strength of the wing, creating conditions for double-sided power generation.

[0155] The specific implementation method of step S03 is to design the fan-shaped distribution structure of the support cross bars according to the wing rib distribution determined in the second step. First, determine the starting point (located on the main beam) and the ending point (located on the trailing edge) of the support cross bars. The mapping relationship between the spatial distribution density of the support cross bars and the trailing edge width can be expressed as:

[0156]

[0157] Wherein, d(r) is the spacing of the support cross bars at the spanwise position r; d0 is the minimum spacing at the wing root, and the value range is 50mm to 80mm; d1 is the maximum spacing at the wing tip, and the value range is 100mm to 150mm; w(r) is the trailing edge width at the spanwise position r; w min and w max are the minimum and maximum widths of the trailing edge respectively; r is the normalized distance from the wing root to the wing tip, and the range is [0, 1]. Using the radial basis function interpolation algorithm, it can be expressed as:

[0158]

[0159] Wherein, f(x) is the interpolation function; λi is the weight coefficient; φ is the radial basis function, usually a Gaussian function where ε is the shape parameter, usually taking values from 0.01 to 0.1; ||x - x i || is the Euclidean distance from point x to the known point x i . The cross-section of the support cross-bar is designed as an I-beam to reduce weight while ensuring strength. The material of the support cross-bar is selected as a carbon fiber composite material with an elastic modulus not lower than 230 GPa and a density not higher than 1.6 g / cm 3 . After completing the layout design of the support cross-bar, the bifacial power generation efficiency of the solar cell module is measured again at each grid point position, the data is recorded, and the second modified power generation efficiency matrix is constructed. The purpose of this step is to ensure that the bifacial solar cell module obtains sufficient mechanical support and at the same time forms a scientific fan-shaped distribution structure to optimize the sunlight transmittance.

[0160] The specific implementation manner of step S04 is the same as the foregoing and will not be elaborated in detail here.

[0161] The specific implementation manner of step S05 is to design and optimize the thickness distribution of the PMI foam substrate. First, an optical transmission and reflection model is established. This model is based on the Fresnel formula and the Beer-Lambert law and is used to predict the transmission and reflection characteristics of light by PMI foam with different thicknesses. The transmittance is calculated as:

[0162] T = (1 - R)·e -α·d ;

[0163] In the formula, T is the transmittance; R is the reflectance, which is calculated by the Fresnel formula: where n1 and n2 are the refractive indices of air and PMI foam respectively, θ i is the incident angle, θ t is the refraction angle, which is calculated by Snell's law n1sinθ i = n2sinθ t . α is the absorption coefficient, which is related to the material and the wavelength of light. For PMI foam, the empirical formula can be used Among them, α0 is the absorption coefficient at the reference wavelength λ0, k is the material characteristic parameter; d is the material thickness. Input the refractive index of PMI foam (usually 1.05 - 1.15), the absorption coefficients of sunlight at different wavelengths, the incident light angle distribution, and the thickness parameter of PMI foam into the model. According to the model calculation results, design the thickness gradient distribution of the PMI foam substrate so that the thickness of the PMI foam at the wing root is 8 - 10 mm (ensuring sufficient strength), and the thickness at the wing tip is 3 - 5 mm (reducing weight). The thickness change uses a cubic spline function for smooth transition to avoid stress concentration caused by sudden changes. Apply the designed PMI foam substrate to the wing structure, measure the power generation efficiency of the double-sided solar cell module at each grid point, and construct the second reverse change power generation efficiency matrix. Through this step, utilize the light transmittance and reflection characteristics of PMI foam to optimize the light intensity distribution received on the back and improve the back-side power generation gain.

[0164] The specific implementation of step S06 is to perform comprehensive optimization analysis based on the power generation efficiency matrix obtained from the first five steps. First, establish a multi-objective optimization equation set, including a structural strength equation, a mass distribution equation, a light transmittance equation, and a power generation efficiency equation. Structural strength equation:

[0165]

[0166] In the formula, σ max is the maximum stress; M max is the maximum bending moment; y max is the maximum distance from the cross-section edge to the neutral axis; I x is the cross-sectional moment of inertia; σ yield is the material yield strength; SF is the safety factor, and the minimum value is 1.5. For the finite element analysis of the wing structure, the stiffness matrix equation is:

[0167] [K]{u} = {F};

[0168] In the formula, [K] is the stiffness matrix; {u} is the node displacement vector; {F} is the node force vector. Mass distribution equation:

[0169]

[0170] In the formula, m total is the total mass of the wing; n s is the number of structural components; ρ i is the material density of the i-th structural component; V i is the volume of the i-th structural component; ρ cell is the surface density of the double-sided solar cell module; A cell is the area of the double-sided solar cell module; m conn is the mass of the connecting material. Center of gravity position calculation:

[0171]

[0172] Wherein, is the position vector of the wing center of gravity; m i is the mass of the i-th structural member; is the position vector of the center of gravity of the i-th structural member; is the position vector of the center of gravity of the double-sided solar cell module; is the position vector of the center of gravity of the connecting material. Transmittance equation:

[0173] I back = I0·T skin ·T PMI ·(1 - B struct );

[0174] Wherein, I back is the effective light intensity reaching the back surface of the double-sided solar cell module; I0 is the incident light intensity; T skin is the transmittance of the lower skin, with a value greater than 95%; T PMI is the transmittance of the PMI foam substrate, whose value is determined by the thickness and calculated through the previous transmittance formula; B struct is the shielding rate of the wing internal structure, defined as the ratio of the projected area of the structural member in the wing plane to the total area of the wing. Power generation efficiency equation:

[0175]

[0176] Wherein, η total is the comprehensive power generation efficiency of the double-sided solar cell module; I front is the incident light intensity on the front surface; I back is the incident light intensity on the back surface; η front is the front surface efficiency coefficient, with a value range of 22% - 26%; η back is the back surface efficiency coefficient, with a value range of 18% - 22%; β is the temperature coefficient, usually with a value of 0.004 - 0.005 / °C; T is the operating temperature of the double-sided solar cell module; T ref is the reference temperature, usually 25°C. The genetic algorithm is used to solve the multi-objective optimization problem, and the fitness function is:

[0177] F(X) = w1·f1(X) + w2·f2(X) + w3·f3(X) + w4·f4(X);

[0178] Wherein, F(X) is the total fitness function; X is the design variable vector, including the main beam section parameters, the distribution position of wing ribs, the layout of support crossbars, the thickness distribution of PMI foam substrate, and the material parameters of the lower skin, etc.; f1(X) to f4(X) are the objective functions of structural strength, mass, light transmittance, and power generation efficiency respectively; w1 to w4 are the weight coefficients, satisfying w1 + w2 + w3 + w4 = 1. Genetic algorithm parameter settings: the population size is 100, the number of evolutionary generations is 50, the crossover probability is 0.8, and the mutation probability is 0.1. Through algorithm iteration, the Pareto optimal solution set is found, and the solution with the best comprehensive performance is selected as the final design scheme to construct the optimal change matrix. The purpose of this step is to find the best balance point among multiple objective functions and obtain the optimal design parameters of the wing structure.

[0179] The specific implementation of step S07 is to conduct a detailed design of the wing rib structure according to the calculation results of the optimal change matrix. Using the parametric design method, the internal structure of the wing rib is designed as a honeycomb shape, and the unit size distribution can be expressed as:

[0180] L(r) = L root +(L tip -L root )·r;

[0181] Wherein, L(r) is the honeycomb unit size at the spanwise position r; L root is the unit size at the wing root, with a value of 15 - 20 mm; L tip is the unit size at the wing tip, with a value of 25 - 30 mm; r is the normalized distance from the wing root to the wing tip, ranging from [0, 1]. The honeycomb wall thickness distribution can be expressed as:

[0182]

[0183] Wherein, t(r) is the honeycomb wall thickness at the spanwise position r; t root is the wall thickness at the wing root, with a value of 1.2 - 1.5 mm; t tip is the wall thickness at the wing tip, with a value of 0.8 - 1.0 mm; r is the normalized distance from the wing root to the wing tip, ranging from [0, 1]. The honeycomb structure is further optimized through the topology optimization algorithm, appropriately increasing the structural density in the stress concentration area and reducing the material usage in the low stress area. The wire passing hole is designed as an ellipse, the major axis is parallel to the wing span, the length of the major axis is 20 - 25 mm, and the length of the minor axis is 10 - 12 mm. Through finite element analysis, it is ensured that the stress concentration coefficient around the wire passing hole does not exceed 1.5. The wing rib material is selected as aviation grade aluminum alloy or carbon fiber composite material, and the density does not exceed 2.7 g / cm 3, the yield strength is not less than 400 MPa. The purpose of this step is to achieve the lightweight and high light transmittance of the rib structure, while ensuring sufficient structural strength and stiffness, creating favorable conditions for double-sided power generation.

[0184] The specific implementation of step S08 is the same as the foregoing, and will not be elaborated in detail here.

[0185] The specific implementation of step S09 is to make final adjustments and optimizations to the design according to the test results. First, analyze the test data under different height simulation conditions, and establish a relationship model between power generation efficiency and height and light conditions. Use the multiple regression analysis method to find out the key factors affecting power generation efficiency and their weights. According to the analysis results, focus on the fine adjustment of the thickness distribution of the PMI foam substrate, and use the gradient descent method to finally optimize the PMI foam thickness. The iteration formula is:

[0186]

[0187] In the formula, is the PMI foam thickness at the i-th position in the k-th iteration; is the PMI foam thickness at the i-th position in the (k + 1)-th iteration; α is the learning rate, usually taking a value of 0.05 - 0.1; is the partial derivative of the comprehensive power generation efficiency with respect to the PMI foam thickness at the i-th position, approximately calculated by the finite difference method: where Δd is a small perturbation, usually taking a value of 0.1 mm. Usually, the adjustment range of the PMI foam thickness is within ±2 mm. The adjustment process uses the gradient descent method, the step size is set to 0.2 mm, and the number of iterations does not exceed 20 times. After the adjustment is completed, the final PMI foam substrate thickness distribution parameters are obtained. The design of the PMI foam substrate thickness gradient uses a cubic spline function:

[0188] d(r) = a0 + a1r + a2r 2 + a3r 3 ;

[0189] In the formula, d(r) is the PMI foam substrate thickness at the spanwise position r; a0, a1, a2, a3 are undetermined coefficients, calculated from the boundary conditions; r is the normalized distance from the wing root to the wing tip, with a range of [0, 1]. The boundary conditions are: d(0) = d root , d(1) = d tip , d′(0) = s root , d′(1) = s tip , where d root is the PMI foam thickness at the wing root, taking a value of 8 - 10 mm; d tip is the PMI foam thickness at the wing tip, taking a value of 3 - 5 mm; sroot and s tip are the thickness change rates at the wing root and wing tip respectively. Using the boundary conditions, the coefficients can be solved: a0 = d root ; a1 = s root ; a2 = 3(d tip - d root ) - 2s root - s tip ; a3 = 2(d root - d tip ) + s root + s tip . Combining all design parameters, a complete design document is formed, including the cross-sectional dimensions of the main beam, the distribution positions of the wing ribs, the layout of the support crossbars, the thickness distribution of the PMI foam substrate, and the material parameters of the lower skin, etc. The purpose of this step is to finely optimize the design based on the measured data to make the double-sided generator wing structure of the solar UAV reach the best performance state, and finally improve the flight altitude and endurance of the solar UAV.

[0190] For a better understanding and implementation of the present invention, Example 2 of a specific application scenario of the present invention is provided below: As Figures 2 to 4 shown, this embodiment provides a double-sided generator wing structure for a solar UAV. Through unique design, the solar cell module can simultaneously use the direct sunlight on the upper surface and the reflected light on the lower surface for power generation, thereby improving the energy acquisition efficiency of the solar UAV.

[0191] In this embodiment, the double-sided generator wing structure of the solar UAV includes a wing 10, a double-sided solar cell module 11, and a lower skin 12. The interior of the wing 10 adopts a hollow structure design and is mainly composed of a leading edge 101, a main beam 102, wing ribs 103, support crossbars 104, and a trailing edge 105. Among them, the main beam 102 is made of high-strength carbon fiber composite material, with an I-shaped cross-section, a height of 35 mm, a width of 15 mm, a wall thickness of 1.2 mm, an elastic modulus reaching 235 GPa, and a compressive strength of 1650 MPa. The main beam 102 spans the entire wing 10 and is the main load-bearing member of the wing 10, directly connected to the fuselage structure.

[0192] The wing ribs 103 are made of aerospace-grade aluminum alloy 7075-T6 material, with a thickness of 1.5 mm and a density of 2.81 g / cm 3, the yield strength is 505 MPa. The number of wing ribs 103 is 12 groups, which are evenly distributed in the span direction with a spacing of 420 mm, and are fixedly connected to the main beam 102 through a slot structure. The depth of the slot is 15 mm and the width is 15.2 mm, providing an assembly gap of 0.2 mm. The interior of the wing rib 103 is designed as a honeycomb lightweight structure, and the unit size changes linearly from the wing root to the wing tip. The unit size at the wing root is 18 mm, and the unit size at the wing tip is 27 mm. Multiple groups of wire-through holes 13 with irregular shapes are opened on the wing rib 103. The main wire-through holes 13 are designed in an oval shape, with a major axis length of 22 mm and a minor axis length of 11 mm. The major axis is parallel to the span direction of the wing 10, reducing structural stress concentration.

[0193] The leading edge 101 and the trailing edge 105 are respectively arranged at the front and rear ends of the wing rib 103 and are fixedly connected to the wing rib 103 by riveting. The leading edge 101 is made of aluminum alloy material with a thickness of 0.8 mm, a leading edge radius of 25 mm, and the surface is coated with an aerodynamic optimization coating. The trailing edge 105 is made of carbon fiber composite material with a thickness of 1.0 mm, a trailing edge angle of 15°, and a bonding area for the double-sided solar cell module 11 with a width of 20 mm is provided on the trailing edge, and high-strength epoxy resin glue is used for bonding.

[0194] The support crossbar 104 is made of carbon fiber composite material, with an I-shaped cross-section, a height of 10 mm, a width of 8 mm, and a wall thickness of 0.8 mm. The support crossbar 104 is fixedly connected to multiple groups of wing ribs 103 and is designed with a fan-shaped distribution structure, radiating from the main beam 102 to the trailing edge 105. At the wing root, the spacing of the support crossbars 104 is 65 mm, and at the wing tip, the spacing increases to 125 mm. The density changes with the width of the trailing edge 105, ensuring sufficient strength at the rear of the wing 10 while maximizing the light transmission area.

[0195] The double-sided solar cell module 11 is a double-sided solar cell panel with a thickness of 2.5 mm, using monocrystalline silicon cell technology. The power generation efficiency of the front surface is 24.8%, and the power generation efficiency of the rear surface is 20.5%. The total area is 4.2 m 2 . The lower substrate of the double-sided solar cell module 11 uses a light-transmissive PMI foam layer 14 with a light transmittance of 88%. The thickness is distributed in a gradient in the span direction of the wing 10, being 9 mm at the wing root and 4 mm at the wing tip, to enhance the structural strength and reduce the weight.

[0196] The lower skin 12 is made of a modified polyethylene terephthalate (PET) film with transparent material and tensile properties. The thickness is 0.15 mm, the light transmittance reaches 96%, the tensile strength is 145 MPa, the elongation at break is 18%, and the anti-ultraviolet performance is excellent. The lower skin 12 is fixedly connected to the bottom of the leading edge 101, the wing rib 103 and the trailing edge 105 through a special epoxy resin adhesive to form a closed lower surface of the wing 10, which can transmit sunlight and maintain a certain aerodynamic shape.

[0197] Based on the above basic structure, the researchers designed an optimization method to further improve the power generation efficiency of the double-sided generator wing structure of the solar UAV. The optimization process is mainly divided into the following steps:

[0198] First, a basic power generation efficiency matrix of the double-sided solar cell module 11 was established. On a standard test platform, a 10×10 grid dot matrix was set on the surface of the wing 10, and samples of the double-sided solar cell module 11 with standard size (100 mm×100 mm) were placed at each grid point for testing. The average power generation efficiency of the front surface under standard illumination (1000 W / m 2 ) was 24.8%, and the average power generation efficiency of the rear surface under the same conditions was 20.5%. The test temperature was controlled at 25±2 °C, and the relative humidity was controlled at 45%±5%. The data obtained through the test were used to construct a basic power generation efficiency matrix, which provided a reference standard for subsequent optimization.

[0199] Based on the basic efficiency matrix, the distribution spacing between the main beam 102 and the wing rib 103 was designed using a space-filling optimization algorithm. The space of the wing 10 structure was divided by the Voronoi diagram algorithm, and the number of initial seed points was 24. After 50 iterations of optimization by the simulated annealing algorithm, the final seed point distribution was determined, so that the distribution of the wing rib 103 not only met the structural strength requirements (minimum safety factor 1.62), but also maximized the light transmission performance (light transmission area ratio reached 78.5%). Compared with the original equal-spacing distribution, the optimized distribution of the wing rib 103 increased the light transmittance by about 3.2% while ensuring the strength. Figure 5It shows the influence of different wing rib distribution methods on the light transmittance of the wing structure. In the figure, the horizontal axis represents the spanwise position of the wing from the wing root to the wing tip, and the vertical axis represents the light transmittance. The chart contains three curves, representing three different structural optimization schemes respectively: the blue curve represents the original equally spaced wing rib distribution, the red curve represents the wing rib distribution optimized by the Voronoi algorithm, and the green curve represents the distribution further optimized by fan-shaped support crossbars on the basis of Voronoi optimization. The specific positions of the wing ribs under different schemes are marked by dashed lines in the figure. The blue dashed line represents the original equally spaced distribution, and the red dashed line represents the optimized distribution. The light transmittance values of three key points are also marked in the chart. The light transmittance at a certain point of the equally spaced distribution is 75.2%, the light transmittance at the middle position of the Voronoi optimized distribution is 78.5%, and the light transmittance of the fan-shaped support crossbar optimized distribution near the wing tip reaches 81.7%.

[0200] For the layout of the support crossbar 104, the original parallel distribution was changed to a fan-shaped distribution structure, and the mapping relationship between the spacing of the support crossbar 104 and the width of the trailing edge 105 was established through the radial basis function interpolation algorithm. The optimized support crossbar 104 is more densely distributed at the wing root of the wing 10 (spacing 65 mm) and more sparsely distributed at the wing tip (spacing 125 mm), forming a distribution pattern that conforms to the force characteristics. After testing, the second modified power generation efficiency matrix was formed. Compared with the original layout, the optimized layout of the support crossbar 104 reduced the structural weight by about 8.5% and increased the average power generation efficiency of the double-sided solar cell module 11 by 0.7 percentage points at the same time.

[0201] To improve the light transmittance, the material of the original lower skin 12 was replaced with a high light transmittance modified PET film, and the light transmittance was increased from the original 91% to 96%. The reflected light intensity distribution was measured by an optical test device, and the first reverse modified power generation efficiency matrix was constructed. After the material replacement, the effective light intensity reaching the back of the double-sided solar cell module 11 increased by about 5.5%, and the comprehensive power generation efficiency increased by about 1.2 percentage points.

[0202] The thickness gradient of the PMI foam layer 14 was optimized. Based on the optical transmission and reflection model, the relationship between the thickness and the reflected light energy conversion was analyzed, and the thickness gradient distribution was designed by a cubic spline function, so that the thickness of the PMI foam layer 14 at the wing root of the wing 10 is 9 mm and the thickness at the wing tip is 4 mm. The parameters of the spline function were determined by coefficient calculation: a0 = 9, a1 = -1.5, a2 = -3.5, a3 = 3. After the thickness of the PMI foam layer 14 was optimized, the second reverse modified power generation efficiency matrix was formed, and the back power generation efficiency was increased by about 0.8 percentage points compared with the uniform thickness design.

[0203] The above five efficiency matrices were superimposed and analyzed to construct an optimal change matrix, with weight coefficients of 0.15, 0.25, 0.25, 0.2, and 0.15 respectively. The final dimensional parameters and positional relationships of each component of the wing 10 were determined through a multi-objective optimization equation set. On this basis, the structure of the wing rib 103 was further optimized, adopting a lightweight honeycomb structure and optimizing the shape of the wire passing hole 13 to an ellipse. The weight of the optimized wing rib 103 structure was reduced by 12.5%, the light transmittance was increased by approximately 4.3%, and the stress concentration coefficient was reduced by 35%.

[0204] A sample of the optimized wing 10 structure was prepared and tested under different altitude simulation conditions. The test results are shown in Table 1:

[0205] Table 1 Test results of double-sided power generation efficiency under different altitude simulation conditions

[0206]

[0207] As shown in Table 1, as the altitude increases, the intensity of the reflected light on the back surface increases significantly, and the comprehensive power generation efficiency also increases accordingly. At an altitude of 7000m, the intensity of the reflected light on the back surface reaches 265W / m 2 , which is approximately 23% of the direct light intensity on the front surface, and the comprehensive power generation efficiency reaches 24.7%, which is approximately 0.9 percentage points higher than that under ground test conditions. Figure 6 It shows the relationship between the light intensity distribution and the corresponding power generation efficiency change of the solar UAV at different flight altitudes. The chart adopts a dual Y-axis design, with the left Y-axis representing the light intensity, the right Y-axis representing the power generation efficiency, and the X-axis representing the flight altitude. The blue solid line and circular markers in the figure represent the direct light intensity on the front surface, and the red solid line and square markers represent the reflected light intensity on the back surface. Both increase as the altitude increases, especially the reflected light intensity on the back surface shows a more significant increase. The green dashed line in the figure represents the power generation efficiency on the front surface, the magenta dashed line represents the power generation efficiency on the back surface, and the black dashed line represents the comprehensive power generation efficiency. At positions where the altitude exceeds 5000m, the percentage of the reflected light to the direct light is marked on the chart. A schematic diagram of cloud reflection is also drawn in the figure, with the gray area representing the cloud layer and the yellow arrow representing the light reflection path.

[0208] Based on the test results, the thickness distribution of the PMI foam layer 14 was finally adjusted using the gradient descent method, with the learning rate set to 0.08. After 20 iterations, the final thickness distribution parameters were obtained. The key parameters of the finally optimized double-sided generator wing structure of the solar UAV are shown in Table 2:

[0209] Table 2 Key parameters of the finally optimized double-sided generator wing structure of the solar UAV

[0210]

[0211]

[0212] Traditional solar drones mainly use single-sided power generation solar cells, which only utilize the upper surface to receive direct sunlight for power generation and cannot utilize the reflected light energy received by the lower surface. Even when using double-sided solar cells, the internal structure of the wing in traditional designs is not optimized for backside power generation. The internal structure has serious shading, and the lower skin has a low light transmittance, and the PMI foam layer has poor light transmittance, resulting in a significant reduction in the backside power generation efficiency. In traditional designs, the wing structure usually adopts uniformly distributed wing ribs and parallel arranged support crossbars, without considering light transmission optimization, with a large weight and poor light transmission performance.

[0213] Compared with the traditional solution, the double-sided generator wing structure of the solar drone in this embodiment has achieved remarkable progress through the following technical means: (1) Adopting a hollow wing structure design, using Voronoi diagrams to optimize the distribution of wing ribs, and fan-shaped distributed support crossbars, significantly improving the structural light transmittance; (2) Selecting a high light transmittance PET film as the lower skin, with a light transmittance of 96%, greatly improving the light transmission efficiency; (3) Using a PMI foam layer with good light transmittance as the lower substrate of the solar cell module, and designing a thickness gradient distribution, taking into account structural strength, weight, and light transmittance; (4) Optimizing the inside of the wing rib to be a honeycomb structure, and the wire passing holes are designed as ellipses, reducing the structural weight and improving the light transmittance; (5) Through a multi-objective optimization equation set, comprehensively considering structural strength, mass distribution, light transmittance, and power generation efficiency, realizing the optimization of the overall performance.

[0214] After testing, when the double-sided generator wing structure of the solar drone in this embodiment is at an altitude of 7000m, the backside power generation contribution can reach 17.5% of the total power generation, and the comprehensive power generation efficiency is increased by 15.3% compared with traditional single-sided power generation. At the same time, the optimized structure weight is reduced by about 14.2% compared with the traditional design, improving the endurance of the drone while ensuring strength. This double-sided generator wing structure design provides a reliable energy solution for high-altitude long-endurance solar drones and is of great significance for promoting the development of solar drone technology.

[0215] It should be noted that the detailed explanations of the variables involved in the present invention are shown in Tables 3, 4, and 5 below.

[0216] Table 3 Variable Explanation Table (First Part)

[0217]

[0218]

[0219] Table 4 Variable Explanation Table (Second Part)

[0220]

[0221] Table 5 Variable Explanation Table (Part 3)

[0222]

[0223]

[0224] As mentioned above, it is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered within the protection scope of the present invention.

Claims

1. A double-sided generator wing structure for a solar-powered unmanned aerial vehicle, characterized in that, It includes a wing, a bifacial solar cell module, and a lower skin. The interior of the wing is a hollow structure. The wing includes a leading edge, a main beam, wing ribs, support crossbars, and a trailing edge. A bonding area for the bifacial solar cell module is provided on the trailing edge. The bifacial solar cell module is fixedly installed between the trailing edge and the leading edge. The lower skin is made of a transparent material and is fixedly connected to the bottoms of the leading edge, the wing ribs, and the trailing edge. The lower substrate of the bifacial solar cell module is a PMI foam layer with light transmittance, so that the reflected light irradiates the back of the bifacial solar cell module, and the power generation efficiency of the bifacial solar cell module is improved through the power generation gain on the back.

2. The double-sided generator wing structure of a solar-powered unmanned aerial vehicle according to claim 1, wherein, The number of the wing ribs is multiple groups, which are distributed at equal intervals and fixedly connected to the main beam, and are used to cooperate with the main beam to ensure the structural strength of the wing and reduce the weight; the leading edge and the trailing edge are respectively arranged at the front and rear ends of the wing ribs and are fixedly connected to the wing ribs; the support crossbars are fixedly connected to multiple groups of the wing ribs and are used to keep the shape of the bifacial solar cell module.

3. The double-sided generator wing structure of a solar UAV according to claim 2, characterized in that Multiple groups of wire-passing holes with irregular shapes are formed in the wing ribs for facilitating wire routing; the wing is fixedly connected to the fuselage structure through the main beam; a card slot adapted to the main beam is formed in the wing rib, and the wing rib is fixedly connected to the main beam through the card slot.

4. A double-sided generator wing structure of a solar UAV according to claim 3, characterized in that, The lower skin has tensile properties. The bifacial solar cell module is a bifacial solar panel, and one end of its back surface uses the light reflected by the ground and clouds for power generation. The bifacial solar cell module is adhesively bonded to the edge of the wing structure through epoxy glue, and the entire wing structure is a hollow design to facilitate the entry of sunlight.

5. An optimization method for the double-sided generator wing structure of a solar unmanned aerial vehicle, which is used to optimize the double-sided generator wing structure of the solar unmanned aerial vehicle described in any one of claims 1 to 4, characterized in that, Including: Establish a basic power generation efficiency matrix of the bifacial solar cell module; Adopt a space-filling optimization algorithm to design the distribution spacing between the main beam and the wing ribs, and construct a first structural change power generation efficiency matrix; Adjust the layout of the support crossbars to a fan-shaped distribution structure to form a second change power generation efficiency matrix; Replace the lower skin material with a high light transmittance polyester film to construct a first reverse change power generation efficiency matrix; change the thickness gradient of the PMI foam substrate to establish a second reverse change power generation efficiency matrix; use the five efficiency matrices for superposition analysis to construct an optimal change matrix; design a new wing rib structure based on the optimal change matrix; Prepare a sample of the optimized wing structure and test the bifacial power generation efficiency under different height simulation conditions; adjust the thickness distribution of the PMI foam substrate according to the test data to form the final optimized design parameters.

6. The optimization method of the double-sided generator wing structure of a solar UAV according to claim 5, characterized in that Establishing a basic power generation efficiency matrix of the bifacial solar cell module means dividing the wing surface into several regional grids, recording the front surface power generation efficiency and the back surface power generation efficiency at each grid point to form a two-dimensional data table for determining the initial power generation performance distribution.

7. The optimization method of the double-sided generator wing structure of a solar UAV according to claim 6, characterized in that The space filling optimization algorithm refers to a calculation method that determines the optimal seed point distribution so that the regions divided by the Voronoi diagram meet the wing structure strength requirements and maximize the light transmission area; the Voronoi diagram refers to a space partitioning method that divides a plane or space into several regions, each region contains a seed point, and the distance from any point within the region to its own seed point is less than the distance to any other seed point.

8. The optimization method of the double-sided generator wing structure of a solar UAV according to claim 7, characterized in that The fan-shaped distribution structure means that the support crossbars are radially arranged from the main beam to the trailing edge, and the density changes with the trailing edge width, ensuring sufficient strength at the rear of the wing while maximizing the light transmission area; the high light transmittance polyester film refers to a modified polyethylene terephthalate material with a light transmittance exceeding 95% and ultraviolet resistance. The PMI foam substrate thickness gradient means that from the wing root to the wing tip, the PMI foam substrate thickness changes according to a non-linear relationship, being thicker in the root region to enhance the structural strength and thinner in the wing tip region to reduce weight, while ensuring the overall optimal light transmittance.

9. The optimization method of the double-sided generator wing structure of a solar UAV according to claim 8, characterized in that, The design of the new wing rib structure includes using a lightweight honeycomb structure and optimizing the wire passing hole shape to an elliptical wire passing hole; the honeycomb structure refers to a lightweight design with a hexagonal grid arrangement inside the wing rib, reducing weight and increasing the light penetration area while ensuring the structural strength; the elliptical wire passing hole refers to an elliptical opening with the major axis parallel to the wing span direction.

10. The optimization method of the double-sided generator wing structure of a solar UAV according to claim 9, characterized in that, The optimization process uses a multi-objective optimization equation set, including a structural strength equation, a mass distribution equation, a light transmittance equation, and a power generation efficiency equation. By comprehensively considering the wing structure strength, mass distribution, light transmission performance, and power generation efficiency, the size parameters and position relationships of each component of the wing structure are determined; the final optimized design parameters include the main beam cross-section size, wing rib distribution position, support crossbar layout, PMI foam substrate thickness distribution, and the light transmittance of the lower skin material, which are used to guide the manufacturing and assembly of the double-sided generator wing structure of the solar drone.

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