A method for optimizing the layout of an unmanned aerial vehicle landing gear system

Abstract

The application relates to the technical field of unmanned aerial vehicle structure design and optimization, and discloses a layout optimization method based on an unmanned aerial vehicle landing gear system. The method comprises the following steps: a three-dimensional design model of the landing gear is constructed; real flight attitude data and a load spectrum are imported; stress nephograms and displacement fields under multiple working conditions are dynamically generated to accurately identify a region to be optimized; preset layout rule library is used for iterative adjustment; component layout is optimized until mechanical indexes are met; the optimized model is compared with a historical failure case database; a risk component list with geometric or mechanical similarity is extracted; and local reinforcement or topological reconstruction is carried out according to the risk component list to generate a final scheme. The method fuses dynamic load analysis and historical failure data, improves the accuracy of layout design, and identifies and prevents potential structural failure risks.

Description

Technical Field

[0001] This invention relates to the field of unmanned aerial vehicle (UAV) structural design and optimization technology, specifically a layout optimization method based on the UAV landing gear system. Background Technology

[0002] The current layout design of UAV landing gear mainly relies on engineers' experience and static mechanical analysis. Conventional methods typically involve applying several preset ultimate load conditions to a 3D model in finite element analysis software to calculate the stress and deformation of the structure. However, this method uses discrete and fixed load conditions, failing to fully consider the complex situation of continuous attitude changes and dynamic load coupling during actual UAV flight missions. Consequently, designs based on this simplified analysis may not accurately identify localized stress concentrations or abnormal deformation areas that only appear during real maneuvering flight, creating potential hazards for structural fatigue and failure.

[0003] After initial optimization based on strength and stiffness, existing technologies typically rely on calculated safety factors or comparisons with similar designs for scheme confirmation, lacking proactive, data-driven early warning of potential failure modes. Even if the optimized model meets all theoretical verification criteria, some components in its structure may still have geometric shapes or stress states similar to components that have historically failed, and these hidden risks are difficult to detect in a timely manner through traditional experience or conventional verification methods. Therefore, how to integrate real dynamic flight loads into the design process and how to proactively avoid similar risks using existing failure knowledge have become key issues in improving the reliability and safety margin of landing gear layout design. Summary of the Invention

[0004] The purpose of this invention is to provide a layout optimization method for unmanned aerial vehicle (UAV) landing gear systems to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides a layout optimization method for a UAV landing gear system, the method comprising: Construct a three-dimensional design model that includes the topological relationships, physical properties, spatial coordinates, and environmental boundaries of the landing structure components; The flight attitude data and load spectrum of the UAV are imported into the three-dimensional design model to dynamically generate stress cloud maps and displacement distribution fields under various working conditions. Based on the stress cloud map and displacement distribution field, stress concentration areas and deformation-sensitive areas in the three-dimensional design model are identified and marked as a set of areas to be optimized. The system calls a pre-set layout rule library, which contains layout criteria based on material mechanics and spatial geometry. Based on the set of regions to be optimized and the layout criteria, the system iteratively adjusts the position, attitude and connection topology of the landing frame components within the three-dimensional design model until the stress and displacement indices of all regions to be optimized meet the preset thresholds, and outputs the optimized three-dimensional design model. The optimized 3D design model is compared with a historical failure case database, and components in the optimized 3D design model that have geometric or mechanical similarity to historical failure structures are extracted to form a list of risky components. Based on the risk component list, the optimized 3D design model is locally reinforced or its topology is reconstructed to generate the final layout scheme.

[0006] Preferably, the dynamic generation of stress cloud maps and displacement distribution fields under various working conditions includes: Constraints determined by the flight attitude data are applied to the three-dimensional design model. These constraints include the landing impact direction, the runway yaw moment, and the static support reaction force. According to the load spectrum, dynamic and static loads are applied step by step at the corresponding connection points and bearing surfaces of the three-dimensional design model; The structural response of the three-dimensional design model under each combination of loads and constraints is calculated using a finite element solver. The structural response includes the stress values ​​and displacements of each node. The calculated stress values ​​and displacements at each node are spatially interpolated and rendered to form visualized stress cloud maps and displacement distribution fields, respectively.

[0007] Preferably, the iterative adjustment of the position, attitude, and connection topology of the landing gear components within the three-dimensional design model includes: Select the region with the highest stress concentration from the set of regions to be optimized as the current adjustment target; Query the layout rule base to obtain at least one layout rule that matches the component type and stress mode of the current adjustment target; Based on the obtained layout criteria, calculate one or more candidate adjustment vectors for the component to which the current adjustment target belongs, wherein the candidate adjustment vectors include translation direction and distance, rotation angle or local topology change scheme; A candidate adjustment vector is applied to the three-dimensional design model, and the stress cloud map and displacement distribution field after the application are recalculated to determine whether the stress and displacement indices of the current adjustment target are better than before the adjustment and meet the preset threshold. If the conditions are met, the adjustment is confirmed and the 3D design model is updated; otherwise, the next candidate adjustment vector is applied. Repeat the selection, query, calculation, application and judgment steps until the indicators of all regions in the set of regions to be optimized are improved and meet the preset threshold.

[0008] Preferably, the generation of the final layout scheme further includes: After completing iterative adjustments and outputting the optimized 3D design model, each component in the risk component list is mapped in detail to the historical failure case database; For components mapped to specific failure cases, extract the failure modes, critical loads, and improvement measures from those failure cases; Based on the failure modes and critical loads, local mechanical analysis is performed on the components in the risk component list that are mapped to specific failure cases in the optimized three-dimensional design model to verify whether they have failure risks within the load spectrum range. If there is a risk, at least one of the improvement measures shall be adopted to reinforce the geometry, material thickness or connection method of the component to complete the local reinforcement. For components that are not mapped to specific failure cases but have high similarity, redundant support structures are added around them or their force transmission paths are changed to complete topology reconstruction. All reinforcement and reconstruction operations are completed within the three-dimensional design model, ensuring that the newly introduced structure does not interfere with the original components, thereby generating the final layout scheme.

[0009] Preferably, the step of performing local mechanical analysis on the components in the risk component list mapped to specific failure cases in the optimized three-dimensional design model includes: From the optimized 3D design model, individual components and their directly connected local structures in the risk component list are separated to form a substructure model; Apply specific load conditions extracted from the load spectrum and the failure cases to the substructure model; Finite element analysis was performed on the substructure model using a fine mesh to obtain its detailed stress distribution, strain energy density, and potential crack initiation locations under the specific load. The maximum stress value obtained from the analysis is compared with the allowable stress of the material in the failure case, and the strain energy density distribution is compared with the failure mode to quantitatively assess its failure risk.

[0010] Preferably, the enhancement modification of the geometry, material thickness, or connection method of the component by adopting at least one of the improvement measures includes: If the improvement measure is a geometric modification, the outline of the component is reshaped in the three-dimensional design model, including increasing the fillet radius, adding reinforcing ribs, or changing the cross-sectional shape to improve stress flow lines; If the improvement measure is to modify the material thickness, then the thickness distribution of the specified area of ​​the component is adjusted in the three-dimensional design model to ensure that the high-stress area has a sufficient load-bearing cross section; If the improvement measure is a modification of the connection method, then the connection type between the component and the adjacent component is changed in the three-dimensional design model, including changing the single bolt connection to multiple bolts or welding, and updating the corresponding mechanical connection relationship; After each modification, the local mechanical analysis of the substructure model must be performed again until the risk of failure is confirmed to be eliminated.

[0011] Preferably, the construction of the three-dimensional design model includes: Collect the original computer-aided design geometric data, material grades, quality properties, and assembly relationships of all components of the landing gear system; Define a global coordinate system, transform and integrate the geometric data of each component into the global coordinate system, and establish a preliminary spatial assembly; Each component in the spatial assembly is assigned a corresponding physical property, and a mechanical connection relationship is established between the components based on the assembly relationship. The mechanical connection relationship includes hinge, fixed connection and contact. A virtual design space surrounding the space assembly is defined as the environmental boundary, which limits the maximum spatial range in which the landing gear system can be laid out. The integrated spatial assembly, physical properties, mechanical connections, and environmental boundaries are combined to form the three-dimensional design model.

[0012] Preferably, importing the UAV's flight attitude data and payload spectrum into the three-dimensional design model includes: Establish the transformation relationship between the global coordinate system of the 3D design model and the UAV body coordinate system; The flight attitude data, including pitch angle, roll angle and yaw angle, are applied to the three-dimensional design model according to the conversion relationship, so that the three-dimensional design model is in a simulated real flight attitude. The load spectrum is analyzed, which defines the magnitude, direction, and time history of the forces and moments acting on the landing gear connection points during different flight phases. Based on the transformation relationship and the current flight attitude, the force and moment vectors defined in the load spectrum are accurately mapped to the corresponding connection point positions in the three-dimensional design model; After mapping is completed, the three-dimensional design model will have the boundary conditions to withstand specific time-varying loads under specific postures.

[0013] Preferably, the construction and invocation of the layout rule base includes: This study collects and formalizes the recognized classical layout principles in the field of aerospace structural design, which involve stress homogenization, deformation compatibility, lightest weight and space compactness. Each principle is transformed into judgment logic and adjustment suggestions that can be executed by the computer, forming a layout guideline; All layout criteria are categorized and indexed according to the applicable component types, load conditions and optimization objectives, and stored in the database to form the layout rule library; When invoked, based on the characteristics of the regions in the set of regions to be optimized, including the type of component, stress mode and spatial location, the system indexes and matches the most relevant layout criteria from the layout rule base for subsequent adjustments.

[0014] Preferably, the verification of the final layout scheme includes: Import all the geometric and attribute information of the final layout scheme into an independent dynamic simulation environment; In the dynamic simulation environment, a more complex landing and taxiing scenario, including a runway model and aerodynamic disturbances, is constructed. The final layout scheme is driven to perform a complete take-off and landing cycle in the scenario, and its dynamic structural response is recorded; Extract the maximum dynamic stress, fatigue damage accumulation, and interference with the airframe components during the simulation process to ensure that all indicators are within the safety margin. Only after verification in the aforementioned dynamic simulation environment is the final layout scheme confirmed as a design output that can guide physical manufacturing.

[0015] Compared with the prior art, the beneficial effects of the present invention are: By importing actual flight attitude data and load spectra of UAVs into a 3D design model, stress cloud maps and displacement distribution fields under various working conditions are dynamically generated, changing the traditional analysis mode that relies on a few static limit conditions. This can simulate the real mechanical response of the structure under continuously changing flight conditions, making the identified stress concentration areas and deformation-sensitive areas closer to the actual loading conditions. Based on this, layout optimization can more effectively adjust material distribution and structural topology, eliminating hidden weak points caused by dynamic loads while ensuring safety, thereby improving the fatigue life of the structure and potentially achieving more precise lightweight design, avoiding redundancy or deficiencies caused by incomplete coverage of working conditions.

[0016] By comparing the optimized 3D model with a historical failure case database and extracting components with geometric or mechanical similarity to form a risk list, a data-driven failure prevention mechanism is introduced. This technology surpasses traditional methods that rely solely on safety factors and design specifications, proactively identifying risky components that "meet theoretical calculations but implicitly contain historical failure characteristics." Local reinforcement or topology reconfiguration based on this list directly correlates design decisions with actual failure modes, ensuring that the final layout not only meets theoretical strength requirements but also effectively avoids known, common structural failure risks, thus improving design maturity and reliability. Attached Figure Description

[0017] Figure 1 This is a schematic diagram illustrating the working principle of the layout optimization method based on the UAV landing gear system described in this invention. Figure 2 A flowchart for dynamically generating stress contour maps and displacement distribution fields; Figure 3 This is a flowchart of the local mechanical analysis; Figure 4 A bar chart comparing stress levels before and after optimization of UAV landing gear components; Figure 5 This is a comparison chart of the maximum stress on the landing gear components of a drone under different operating conditions. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Please see Figure 1This invention provides a layout optimization method for a UAV landing gear system. The method includes: constructing a three-dimensional design model containing the topological relationships, physical properties, spatial coordinates, and environmental boundaries of the landing gear components; importing the UAV's flight attitude data and load spectrum into the three-dimensional design model; dynamically generating stress cloud maps and displacement distribution fields under various working conditions; identifying stress concentration areas and deformation-sensitive areas in the three-dimensional design model based on the stress cloud maps and displacement distribution fields and marking them as a set of areas to be optimized; calling a preset layout rule library; iteratively adjusting the position, attitude, and connection topology of the landing gear components within the three-dimensional design model according to the set of areas to be optimized and the layout criteria based on material mechanics and spatial geometry contained in the layout rule library, until the stress and displacement indices of all areas to be optimized meet preset thresholds; outputting an optimized three-dimensional design model; comparing the optimized three-dimensional design model with a historical failure case database; extracting components in the optimized three-dimensional design model that have geometric or mechanical similarity to historical failed structures to form a risk component list; and combining the risk component list to perform local reinforcement or topological reconstruction on the optimized three-dimensional design model to generate a final layout scheme.

[0020] In one embodiment of the present invention, see [reference] Figure 2The dynamic generation of stress cloud maps and displacement distribution fields under various working conditions includes applying constraints determined by the flight attitude data to the three-dimensional design model. These constraints include the landing impact direction, the yaw moment during takeoff and landing, and the static support reaction force. Dynamic and static loads are applied step by step to the corresponding connection points and bearing surfaces of the three-dimensional design model according to the load spectrum. The structural response of the three-dimensional design model under each load and constraint combination is calculated using a finite element solver. The structural response includes the stress values ​​and displacements of each node. The calculated stress values ​​and displacements of each node are spatially interpolated and rendered to form visualized stress cloud maps and displacement distribution fields. The iterative adjustment of the position, attitude, and connection topology of the landing gear components within the 3D design model includes selecting the region with the highest stress concentration from the set of regions to be optimized as the current adjustment target; querying the layout rule base to obtain at least one layout criterion that matches the component type and stress mode of the current adjustment target; calculating one or more candidate adjustment vectors for the component to which the current adjustment target belongs based on the obtained layout criterion; the candidate adjustment vectors include translation direction and distance, rotation angle, or local topology change schemes; applying a candidate adjustment vector in the 3D design model; recalculating the stress cloud map and displacement distribution field after application; and determining whether the stress and displacement indices of the current adjustment target are better than before adjustment and meet a preset threshold. If they meet the threshold, the adjustment is confirmed and the 3D design model is updated; otherwise, the next candidate adjustment vector is applied, and the steps of selection, query, calculation, application, and judgment are repeated until the indices of all regions in the set of regions to be optimized are improved and meet the preset threshold.

[0021] In practical implementation, dynamically generating stress cloud maps and displacement distribution fields under various working conditions involves applying constraints determined by flight attitude data to the three-dimensional design model. These constraints include the landing impact direction, taxiing yaw moment, and static support reaction force. Dynamic and static loads are applied step by step to the corresponding connection points and bearing surfaces of the three-dimensional design model according to the load spectrum. The structural response of the three-dimensional design model under each load and constraint combination is calculated using a finite element solver. The structural response includes the stress values ​​and displacements of each node. The calculated stress values ​​and displacements of each node are spatially interpolated and rendered to form visualized stress cloud maps and displacement distribution fields.

[0022] In practical implementation, the position, attitude, and connection topology of the landing gear components are iteratively adjusted within the 3D design model. This includes selecting the region with the highest stress concentration from the set of regions to be optimized as the current adjustment target. The stress concentration is quantified using a stress concentration factor, the formula for which is:

[0023] Where: symbol Represents the stress concentration factor, symbol This represents the maximum stress value of all finite element nodes within a certain region of the set of regions to be optimized, with the symbol... This represents the overall average stress value of the 3D design model under the corresponding working condition. The selection process is based on the stress concentration factor. The numerical comparison will The region with the highest value is selected as the current adjustment target. The layout rule base is queried to obtain at least one layout criterion matching the component type and stress mode of the current adjustment target. Based on the obtained layout criterion, one or more candidate adjustment vectors for the component to which the current adjustment target belongs are calculated. Candidate adjustment vectors include translation direction and distance, rotation angle, or local topological change schemes. It is understood that the calculation of candidate adjustment vectors depends on the geometric transformation rules and mechanical optimization objectives defined in the layout criterion. For example, for bending members, the layout criterion may suggest adding support points to reduce the span, thereby generating candidate adjustment vectors for translation or adding connections. A candidate adjustment vector is applied to the 3D design model, and the stress cloud map and displacement distribution field after application are recalculated to determine whether the stress and displacement indices of the current adjustment target are better than before adjustment and meet preset thresholds. Optionally, the preset thresholds include the maximum allowable stress limit and the maximum allowable displacement limit. The judgment process compares the stress concentration factor before and after adjustment. The process is completed by checking if the maximum displacement value has decreased below a threshold. If so, the adjustment is confirmed and the 3D design model is updated; otherwise, the next candidate adjustment vector is applied. The selection, query, calculation, application, and judgment steps are repeated until the indicators of all regions in the set of regions to be optimized are improved and meet the preset threshold. In some embodiments, the iteration process uses automatic loop control logic, updating the set of regions to be optimized after each iteration until the set is empty or the maximum number of iterations is reached.

[0024] In one embodiment of the present invention, generating the final layout scheme further includes, after completing iterative adjustments and outputting the optimized three-dimensional design model, mapping each component in the risk component list to the historical failure case database in detail; extracting the failure modes, critical loads, and improvement measures from the failure cases for components mapped to specific failure cases; performing local mechanical analysis on the components mapped to specific failure cases in the optimized three-dimensional design model based on the failure modes and critical loads to verify whether they have a failure risk within the load spectrum range; if a risk exists, using at least one of the improvement measures to enhance the geometry, material thickness, or connection method of the component to complete local reinforcement; for components not mapped to specific failure cases but with high similarity, adding redundant support structures around them or changing their force transmission path to complete topology reconstruction; all reinforcement and reconstruction operations are completed within the three-dimensional design model, ensuring that the newly introduced structures do not interfere with the original components, thereby generating the final layout scheme.

[0025] In practical implementation, generating the final layout scheme also includes, after completing iterative adjustments and outputting the optimized 3D design model, mapping each component in the risk component list to a historical failure case database in detail. This detailed mapping process involves quantifying and extracting the geometric and mechanical characteristic parameters of the components and comparing them one by one with historical failure structure records in the database. In some embodiments, geometric characteristic parameters include the component's key dimension proportions, cross-sectional shape descriptors, and topological features of connection points; mechanical characteristic parameters include the component's principal stress direction under the load spectrum, the location of maximum deformation, and its role in the force transmission path within the overall structure. For components mapped to specific failure cases, the failure modes, critical loads, and improvement measures from those cases are extracted. Based on the failure modes and critical loads, local mechanical analysis is performed on the components in the risk component list mapped to specific failure cases in the optimized 3D design model to verify whether they pose a failure risk within the load spectrum range. This verification process involves comparing the critical loads extracted from historical cases with the corresponding working condition loads analyzed from the current load spectrum, and simultaneously comparing the similarity between the failure modes and the stress concentration or deformation modes shown in the current local mechanical analysis.

[0026] In practical implementation, if risks exist, at least one of the improvement measures will be used to reinforce the geometry, material thickness, or connection method of the component, achieving local reinforcement. For components that do not map to specific failure cases but have high similarity, redundant support structures will be added around them or their force transmission paths will be changed to achieve topological reconstruction. The quantitative basis for judging high similarity is a comprehensive similarity score, and the formula for calculating the comprehensive similarity score is:

[0027] Where: symbol Indicates the overall similarity score, symbol This represents the normalized geometric similarity value calculated using a 3D shape matching algorithm, with the symbol... This represents the normalized mechanical similarity value calculated by comparing stress distribution and deformation mode under load conditions. The symbol is... and symbols These are the preset weighting coefficients for geometric similarity and mechanical similarity, respectively, and satisfy the following conditions: Optionally, when a component's overall similarity score is... If a component exceeds a preset threshold but no record is precisely matched in the historical failure case database, it is considered to have high similarity. All reinforcement and reconstruction operations are completed within the 3D design model, ensuring that newly introduced structures do not interfere with existing components. In some embodiments, interference checks are implemented through Boolean operations and gap analysis functions in the 3D design model software. Collision detection is performed on any newly added redundant support structures or modified force transmission path components and the original assembly. When a physical intersection or gap less than the safe installation distance is detected, the spatial position and size of the newly added structure or modified component are fine-tuned until there is no interference, thereby generating the final layout scheme.

[0028] In one embodiment of the present invention, see [reference] Figure 3In the optimized 3D design model, local mechanical analysis is performed on the components in the risk component list that are mapped to specific failure cases. This includes separating individual components and their directly connected local structures from the optimized 3D design model to form a substructure model. Specific load conditions extracted from the load spectrum and the failure cases are applied to the substructure model. Finite element analysis is performed on the substructure model using a fine mesh to obtain its detailed stress distribution, strain energy density, and potential crack initiation locations under the specific load. The maximum stress value obtained from the analysis is compared with the allowable stress of the material in the failure case, and the strain energy density distribution is compared with the failure mode to quantitatively assess its failure risk. The enhancement measures include at least one of the following: modifying the geometry, material thickness, or connection method of the component. If the enhancement measure is a geometry modification, the component's outline is reshaped in the 3D design model, including increasing fillet radius, adding reinforcing ribs, or changing the cross-sectional shape to improve stress flow lines. If the enhancement measure is a material thickness modification, the thickness distribution in a specified area of ​​the component is adjusted in the 3D design model to ensure sufficient load-bearing cross-section in high-stress areas. If the enhancement measure is a connection method modification, the connection type between the component and adjacent components is changed in the 3D design model, including changing a single bolt connection to multiple bolts or welding, and updating the corresponding mechanical connection relationships. After each modification, the local mechanical analysis of the substructure model must be performed again until the failure risk is confirmed to be eliminated.

[0029] In practical implementation, local mechanical analysis is performed on components in the risk component list mapped to specific failure cases within the optimized 3D design model. This includes separating individual components and their directly connected local structures from the risk component list into a substructure model. Specific load conditions extracted from the load spectrum and failure cases are applied to the substructure model. Finite element analysis is then performed on the substructure model using a fine mesh to obtain detailed stress distribution, strain energy density, and potential crack initiation locations under specific loads. The maximum stress value obtained from the analysis is compared with the allowable stress of the material in the failure case, and the strain energy density distribution is compared with the failure mode to quantitatively assess the failure risk. In some embodiments, the quantitative assessment of failure risk is accomplished by calculating a risk factor. The formula for calculating the risk factor is:

[0030] Where: symbol Represents risk factors, symbol The peak stress of the substructure model under a specific load condition is represented by the symbol. This represents the allowable stress of the material obtained from the corresponding failure case, with the symbol... This represents the strain energy obtained by integrating over the critical region around the potential crack initiation site, denoted by [symbol missing]. Represents the total strain energy of the entire substructure model, symbol It is a preset coefficient used to balance stress and energy contributions. This can be understood as a risk factor. The higher the value of the risk factor, the higher the risk of component failure. If the value is greater than or equal to 1, it is considered that there is a risk of failure.

[0031] In specific implementation, the improvement measures include enhancing the geometry, material thickness, or connection method of the component. If the improvement measure is a geometric modification, the component's outline is reshaped in the 3D design model, including increasing fillet radii, adding reinforcing ribs, or changing the cross-sectional shape to improve stress flow lines. If the improvement measure is a material thickness modification, the thickness distribution in a specified area of ​​the component is adjusted in the 3D design model to ensure sufficient load-bearing cross-section in high-stress areas. If the improvement measure is a connection method modification, the connection type between the component and adjacent components is changed in the 3D design model, including changing a single bolt connection to multiple bolts or welding, and updating the corresponding mechanical connection relationships. After each modification, a local mechanical analysis of the substructure model must be performed again until the failure risk is confirmed to be eliminated. In some embodiments, performing a new local mechanical analysis means re-executing the finite element solution of the substructure model and calculating new risk factors. When new risk factors When the risk drops below a preset safety threshold, the failure risk is considered eliminated. This safety threshold is understood to be a value less than 1, used to provide a design safety margin. Optionally, if a single improvement measure fails to reduce the risk factor... If the damage drops below the safety threshold, two or more of the following measures must be applied in combination: geometric shape modification, material thickness modification, and connection method modification. Each modification operation must be performed within the same file environment of the 3D design model to maintain the consistency and traceability of the design data, ensuring that the results of geometric shape modification, material thickness modification, or connection method modification are accurately recorded and applied to the subsequent final layout scheme.

[0032] In one embodiment of the present invention, constructing a three-dimensional design model includes collecting the original computer-aided design geometric data, material grades, quality attributes, and assembly relationships of all components of the landing gear system; defining a global coordinate system to transform and integrate the geometric data of each component into the global coordinate system; establishing a preliminary spatial assembly; assigning corresponding physical attributes to each component in the spatial assembly; and establishing mechanical connection relationships between the components based on the assembly relationships, including hinges, fixed connections, and contacts; setting a virtual design space surrounding the spatial assembly as an environmental boundary, which limits the maximum spatial range in which the landing gear system can be laid out; and combining the integrated spatial assembly, physical attributes, mechanical connection relationships, and environmental boundary to form the three-dimensional design model. Importing the UAV's flight attitude data and load spectrum into the 3D design model involves establishing the transformation relationship between the global coordinate system of the 3D design model and the UAV's body coordinate system. The flight attitude data, including pitch angle, roll angle, and yaw angle, are applied to the 3D design model according to the transformation relationship, thereby placing the 3D design model under simulated real flight attitude. The load spectrum is then analyzed. The load spectrum defines the magnitude, direction, and time history of the forces and moments acting on the landing gear connection points at different flight stages. Based on the transformation relationship and the current flight attitude, the force and moment vectors defined in the load spectrum are accurately mapped to the corresponding connection point positions in the 3D design model. After the mapping is completed, the 3D design model possesses the boundary conditions to withstand specific time-varying loads under specific attitudes.

[0033] In practical implementation, constructing a 3D design model involves collecting the original computer-aided design geometric data, material grades, quality attributes, and assembly relationships of all components of the landing gear system. The data collection process involves exporting the point, line, and surface geometric information, as well as material and quality attributes of the components from the product data management system, and extracting the parent-child constraints and mating relationships between components from the product assembly relationship tree. A global coordinate system is defined, and the geometric data of each component is transformed and integrated into the global coordinate system to establish a preliminary spatial assembly. Each component in the spatial assembly is assigned corresponding physical attributes, and mechanical connection relationships are established between components based on the assembly relationships. These mechanical connection relationships include hinges, fixed connections, and contacts. A virtual design space surrounding the spatial assembly is set as the environmental boundary, which limits the maximum spatial range that the landing gear system can be deployed. The integrated spatial assembly, physical attributes, mechanical connection relationships, and environmental boundary together form a 3D design model. In some embodiments, the collected component information is stored and managed in the form of structured data tables (see Table 1). Table 1: Information Table of Landing and Lifting Structure Components

[0034] In practical implementation, importing the UAV's flight attitude data and payload spectrum into the 3D design model involves establishing the transformation relationship between the global coordinate system of the 3D design model and the UAV's body coordinate system. This transformation relationship is defined by a homogeneous transformation matrix, and the matrix calculation formula is as follows:

[0035] Where: symbol This represents the homogeneous transformation matrix from the body coordinate system to the global coordinate system, with the symbol... This represents a translation transformation matrix that considers the offset of the origins of two coordinate systems. The symbol is... ,symbol and symbols These represent the rotation angles around the X, Y, and Z axes of the body coordinate system, respectively. (Rolling angle) (Pitch angle) and The rotation matrix for (yaw angle). It can be understood that the flight attitude data defines the rotation angle. , and The origin offset is determined by the theoretical connection position between the landing gear and the fuselage in the 3D design model. Flight attitude data, including pitch, roll, and yaw angles, are applied to the 3D design model according to transformation relationships, thus simulating the actual flight attitude of the 3D design model. In some embodiments, the application process involves using a matrix... The spatial pose transformation is achieved by applying the node coordinates of all components in the 3D design model. The load spectrum is analyzed; it defines the magnitude, direction, and time history of the forces and moments acting on the landing gear connection points at different flight phases. Based on the transformation relationship and the current flight attitude, the force and moment vectors defined in the load spectrum are accurately mapped to the corresponding connection point positions in the 3D design model. It can be understood that the load vectors are defined in the body coordinate system, requiring the use of matrices. The rotational components are transformed into the global coordinate system of the 3D design model, and the coordinates of the point of application are also transformed into the global coordinate system based on the translational components. Optionally, the load spectrum is stored in a time-load vector table, and the corresponding load value is indexed according to the simulation time step during mapping. After mapping, the 3D design model has the boundary conditions to withstand specific time-varying loads under specific attitudes, which can be used for subsequent finite element analysis.

[0036] See Figure 4This is a bar chart comparing the stress of UAV landing gear components before and after optimization. It shows the stress changes of different components in the UAV landing gear before and after layout optimization, serving as a verification tool for the effectiveness of engineering structural optimization. The stress values ​​of all components decreased significantly after optimization; LG-102 showed the largest optimization effect. After optimization, the stress levels of each component are more uniform, avoiding the risk of local stress concentration. This type of chart is often used to verify the effectiveness of UAV landing gear layout optimization. The reduction in stress indicates that the layout adjustment effectively improved the force transmission path; stress uniformity helps improve the structural safety and fatigue life of the landing gear, directly reflecting the "improvement of structural reliability" in engineering design.

[0037] In one embodiment of the present invention, the construction and invocation of the layout rule base includes collecting and formally describing the classic layout principles recognized in the field of aerospace structural design. These principles involve stress homogenization, deformation coordination, lightest weight, and space compactness. Each principle is transformed into a judgment logic and adjustment suggestion that can be executed by a computer, forming a layout criterion. All layout criteria are classified and indexed according to their applicable component types, load conditions, and optimization objectives, and stored in a database to constitute the layout rule base. When invoked, based on the characteristics of the regions in the set of regions to be optimized, including their component types, stress modes, and spatial locations, the layout rule base is indexed and matched with the most relevant layout criteria for subsequent adjustment. The verification of the final layout scheme includes importing all geometric and attribute information of the final layout scheme into an independent dynamic simulation environment. In the dynamic simulation environment, a more complex landing and taxiing scenario including a runway model and aerodynamic disturbances is constructed. The final layout scheme is driven to perform a complete takeoff and landing cycle in the scenario, and its dynamic structural response is recorded. The maximum dynamic stress, fatigue damage accumulation, and interference with the airframe of the landing gear components are extracted during the simulation process to ensure that all indicators are within the safety margin. Only after the final layout scheme is verified by the dynamic simulation environment can it be confirmed as a design output that can guide physical manufacturing.

[0038] In practical implementation, the construction and retrieval of the layout rule base includes collecting and formalizing the recognized classic layout principles in the field of aerospace structural design. These classic layout principles involve stress homogenization, deformation compatibility, minimum weight, and space compactness. Each principle is transformed into computer-executable judgment logic and adjustment suggestions, forming a layout criterion. This transformation process can be understood as decomposing qualitative design experience into a series of quantifiable conditional judgment statements and parameterized geometric operation instructions. For example, for the "stress homogenization" principle, a corresponding layout criterion might include the logic and suggestion that "if the ratio of the maximum stress to the average stress in a component exceeds a threshold, then it is recommended to increase material or adjust the cross-sectional shape along the principal stress direction." All layout criteria are categorized and indexed according to their applicable component type, load conditions, and optimization objectives, and stored in a database to constitute the layout rule base. During retrieval, based on the characteristics of the regions in the input set of regions to be optimized, including the component type, stress mode, and spatial location, the layout rule base is indexed and matched with the most relevant layout criteria for subsequent adjustments. In some embodiments, the matching relevance is ranked by an evaluation score, calculated using the following formula:

[0039] Where: symbol This represents the evaluation score of a certain layout criterion for a specific region to be optimized, with the symbol [symbol missing]. This indicates the degree of matching between the component type labels preset by the layout criteria and the component type of the area to be optimized. (Symbol) This indicates the degree of matching between the typical load mode description preset by the layout criterion and the force mode of the area to be optimized, with the symbol [symbol missing]. and symbols These are the normalized weighting factors for component type matching degree and load mode matching degree, respectively. Optional, component type matching degree... Matching degree with load mode The value range is set between 0 and 1, where 1 represents a perfect match, and the evaluation score is... Higher layout criteria are considered to be more relevant.

[0040] In practical implementation, the verification of the final layout scheme involves importing all geometric and attribute information of the final layout scheme into an independent dynamic simulation environment. Within this environment, a more complex landing and taxiing scenario, including a runway model and aerodynamic disturbances, is constructed. This independent dynamic simulation environment refers to a software platform capable of multibody dynamics solving and complex contact modeling, separated from the environment previously used for static and quasi-static finite element analysis, to simulate more realistic dynamic interactions. The final layout scheme is driven to perform a complete takeoff and landing cycle within the scenario, and its dynamic structural response is recorded. The maximum dynamic stress, accumulated fatigue damage, and interference with the airframe components are extracted during the simulation, ensuring all indicators remain within safety margins. In some embodiments, accumulated fatigue damage is calculated based on the stress time history extracted from the simulation using Mainner's law, and interference with the airframe is monitored throughout the simulation time domain using a dynamic collision detection algorithm. Only after verification in the dynamic simulation environment is the final layout scheme confirmed as a design output suitable for guiding physical manufacturing. Optionally, if any metric is found to exceed the safety margin during the verification process, it is necessary to backtrack to the previous steps of the layout optimization method, modify the final layout scheme, and re-perform the verification process until all dynamic verification metrics meet the requirements.

[0041] See Figure 5 This is a chart comparing the maximum stress of UAV landing gear components under different operating conditions. It is used to analyze the stress risk of each core component of the landing gear in typical working scenarios and is a key tool for structural reliability assessment. Under heavy-load landing conditions, the stress of all components is at its highest, representing the most severe stress scenario for the landing gear. The stress levels of the main struts and wheel frames are generally higher than those of the shock absorbers and support arms, making them high-stress-risk components of the landing gear. The impact of different operating conditions on component stress varies significantly. These types of charts are mainly used to verify the operating condition adaptability of the landing gear structure, identify high-stress components under extreme conditions such as "heavy-load landing," and carry out targeted local reinforcement; clarify the stress priority of different components under various operating conditions, assisting in optimizing material selection and layout design; and provide key stress data support for subsequent fatigue life analysis and failure risk assessment.

[0042] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0043] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A layout optimization method based on a UAV landing gear system, characterized in that, include: Construct a three-dimensional design model that includes the topological relationships, physical properties, spatial coordinates, and environmental boundaries of the landing structure components; The flight attitude data and load spectrum of the UAV are imported into the three-dimensional design model to dynamically generate stress cloud maps and displacement distribution fields under various working conditions. Based on the stress cloud map and displacement distribution field, stress concentration areas and deformation-sensitive areas in the three-dimensional design model are identified and marked as a set of areas to be optimized. The system calls a pre-set layout rule library, which contains layout criteria based on material mechanics and spatial geometry. Based on the set of regions to be optimized and the layout criteria, the system iteratively adjusts the position, attitude and connection topology of the landing frame components within the three-dimensional design model until the stress and displacement indices of all regions to be optimized meet the preset thresholds, and outputs the optimized three-dimensional design model. The optimized 3D design model is compared with a historical failure case database, and components in the optimized 3D design model that have geometric or mechanical similarity to historical failure structures are extracted to form a list of risky components. Based on the risk component list, the optimized 3D design model is locally reinforced or its topology is reconstructed to generate the final layout scheme.

2. The layout optimization method for a UAV landing gear system according to claim 1, characterized in that, The dynamic generation of stress cloud maps and displacement distribution fields under various working conditions includes: Constraints determined by the flight attitude data are applied to the three-dimensional design model. These constraints include the landing impact direction, the runway yaw moment, and the static support reaction force. According to the load spectrum, dynamic and static loads are applied step by step at the corresponding connection points and bearing surfaces of the three-dimensional design model; The structural response of the three-dimensional design model under each combination of loads and constraints is calculated using a finite element solver. The structural response includes the stress values ​​and displacements of each node. The calculated stress values ​​and displacements at each node are spatially interpolated and rendered to form visualized stress cloud maps and displacement distribution fields, respectively.

3. The layout optimization method based on the UAV landing gear system according to claim 1, characterized in that, The iterative adjustment of the position, attitude, and connection topology of the landing gear components within the three-dimensional design model includes: Select the region with the highest stress concentration from the set of regions to be optimized as the current adjustment target; Query the layout rule base to obtain at least one layout rule that matches the component type and stress mode of the current adjustment target; Based on the obtained layout criteria, calculate one or more candidate adjustment vectors for the component to which the current adjustment target belongs, wherein the candidate adjustment vectors include translation direction and distance, rotation angle or local topology change scheme; A candidate adjustment vector is applied to the three-dimensional design model, and the stress cloud map and displacement distribution field after the application are recalculated to determine whether the stress and displacement indices of the current adjustment target are better than before the adjustment and meet the preset threshold. If the conditions are met, the adjustment is confirmed and the 3D design model is updated; otherwise, the next candidate adjustment vector is applied. Repeat the selection, query, calculation, application and judgment steps until the indicators of all regions in the set of regions to be optimized are improved and meet the preset threshold.

4. The layout optimization method for a UAV landing gear system according to claim 3, characterized in that, The method for generating the final layout scheme also includes: After completing iterative adjustments and outputting the optimized 3D design model, each component in the risk component list is mapped in detail to the historical failure case database; For components mapped to specific failure cases, extract the failure modes, critical loads, and improvement measures from those failure cases; Based on the failure modes and critical loads, local mechanical analysis is performed on the components in the risk component list that are mapped to specific failure cases in the optimized three-dimensional design model to verify whether they have failure risks within the load spectrum range. If there is a risk, at least one of the improvement measures shall be adopted to reinforce the geometry, material thickness or connection method of the component to complete the local reinforcement. For components that are not mapped to specific failure cases but have high similarity, redundant support structures are added around them or their force transmission paths are changed to complete topology reconstruction. All reinforcement and reconstruction operations are completed within the three-dimensional design model, ensuring that the newly introduced structure does not interfere with the original components, thereby generating the final layout scheme.

5. The layout optimization method for a UAV landing gear system according to claim 4, characterized in that, The local mechanical analysis of the components in the risk component list mapped to specific failure cases in the optimized three-dimensional design model includes: From the optimized 3D design model, individual components and their directly connected local structures in the risk component list are separated to form a substructure model; Apply specific load conditions extracted from the load spectrum and the failure cases to the substructure model; Finite element analysis was performed on the substructure model using a fine mesh to obtain its detailed stress distribution, strain energy density, and potential crack initiation locations under the specific load. The maximum stress value obtained from the analysis is compared with the allowable stress of the material in the failure case, and the strain energy density distribution is compared with the failure mode to quantitatively assess its failure risk.

6. The layout optimization method for a UAV landing gear system according to claim 4, characterized in that, The enhancement modification of the geometry, material thickness, or connection method of the component by adopting at least one of the aforementioned improvement measures includes: If the improvement measure is a geometric modification, the outline of the component is reshaped in the three-dimensional design model, including increasing the fillet radius, adding reinforcing ribs, or changing the cross-sectional shape to improve stress flow lines; If the improvement measure is to modify the material thickness, then the thickness distribution of the specified area of ​​the component is adjusted in the three-dimensional design model to ensure that the high-stress area has a sufficient load-bearing cross section; If the improvement measure is a modification of the connection method, then the connection type between the component and the adjacent component is changed in the three-dimensional design model, including changing the single bolt connection to multiple bolts or welding, and updating the corresponding mechanical connection relationship; After each modification, the local mechanical analysis of the substructure model must be performed again until the risk of failure is confirmed to be eliminated.

7. The layout optimization method for a UAV landing gear system according to claim 1, characterized in that, The construction of the three-dimensional design model includes: Collect the original computer-aided design geometric data, material grades, quality properties, and assembly relationships of all components of the landing gear system; Define a global coordinate system, transform and integrate the geometric data of each component into the global coordinate system, and establish a preliminary spatial assembly; Each component in the spatial assembly is assigned a corresponding physical property, and a mechanical connection relationship is established between the components based on the assembly relationship. The mechanical connection relationship includes hinge, fixed connection and contact. A virtual design space surrounding the space assembly is defined as the environmental boundary, which limits the maximum spatial range in which the landing gear system can be laid out. The integrated spatial assembly, physical properties, mechanical connections, and environmental boundaries are combined to form the three-dimensional design model.

8. The layout optimization method for a UAV landing gear system according to claim 7, characterized in that, The process of importing the UAV's flight attitude data and payload spectrum into the three-dimensional design model includes: Establish the transformation relationship between the global coordinate system of the 3D design model and the UAV body coordinate system; The flight attitude data, including pitch angle, roll angle and yaw angle, are applied to the three-dimensional design model according to the conversion relationship, so that the three-dimensional design model is in a simulated real flight attitude. The load spectrum is analyzed, which defines the magnitude, direction, and time history of the forces and moments acting on the landing gear connection points during different flight phases. Based on the transformation relationship and the current flight attitude, the force and moment vectors defined in the load spectrum are accurately mapped to the corresponding connection point positions in the three-dimensional design model; After mapping is completed, the three-dimensional design model will have the boundary conditions to withstand specific time-varying loads under specific postures.

9. The layout optimization method for a UAV landing gear system according to claim 1, characterized in that, The construction and invocation of the layout rule base includes: This study collects and formalizes the recognized classical layout principles in the field of aerospace structural design, which involve stress homogenization, deformation compatibility, lightest weight and space compactness. Each principle is transformed into judgment logic and adjustment suggestions that can be executed by the computer, forming a layout guideline; All layout criteria are categorized and indexed according to the applicable component types, load conditions and optimization objectives, and stored in the database to form the layout rule library; When invoked, based on the characteristics of the regions in the set of regions to be optimized, including the type of component, stress mode and spatial location, the system indexes and matches the most relevant layout criteria from the layout rule base for subsequent adjustments.

10. The layout optimization method for a UAV landing gear system according to claim 1, characterized in that, The verification of the final layout scheme includes: Import all the geometric and attribute information of the final layout scheme into an independent dynamic simulation environment; In the dynamic simulation environment, a more complex landing and taxiing scenario, including a runway model and aerodynamic disturbances, is constructed. The final layout scheme is driven to perform a complete take-off and landing cycle in the scenario, and its dynamic structural response is recorded; Extract the maximum dynamic stress, fatigue damage accumulation, and interference with the airframe components during the simulation process to ensure that all indicators are within the safety margin. Only after verification in the aforementioned dynamic simulation environment is the final layout scheme confirmed as a design output that can guide physical manufacturing.

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