Automobile bracket off-line detection method and system

Abstract

This invention discloses a method and system for detecting off-line automotive brackets, belonging to the field of automotive component testing and analysis technology. It includes: real-time acquisition of vehicle bracket operation data; obtaining a set of working stress points for the bracket through data preprocessing and feature extraction; acquiring a three-dimensional model of the bracket; generating a set of assembly stress points by combining structural topological relationships and assembly constraints; establishing a coupled distribution model of key stress points through spatial mapping and mechanical coupling analysis of the two types of stress points; obtaining a mirror stress deviation model through mirror mapping and symmetry analysis of a symmetrical reference plane; performing quantitative detection and analysis based on preset engineering standards to determine if the structure meets requirements; performing reverse tracing analysis on abnormal stress areas when standards are not met; optimizing and adjusting structural parameters based on causes, and iteratively calculating and outputting a set of corrected parameters. This invention achieves stress fusion, deviation quantification, and closed-loop optimization in off-line bracket detection, improving detection accuracy and consistency.

Description

Technical Field

[0001] This invention relates to the field of automotive parts testing and analysis technology, specifically to a method and system for detecting automotive brackets after they have been installed. Background Technology

[0002] Traditional automotive bracket off-line inspections often employ static single-point loading or manual sampling methods, making it difficult to simultaneously acquire dynamic stress data of the bracket under actual vehicle operating conditions and the constraint transmission path in its assembly state. Existing methods lack spatial mapping and mechanical coupling analysis between working stress points and assembly stress points, failing to effectively identify symmetry deviations and off-center loading conditions in the left and right structures. This results in low inspection accuracy, difficulty in locating the root cause of anomalies, and the inability to form a closed-loop structural optimization, impacting bracket safety and production efficiency. Summary of the Invention

[0003] The purpose of this invention is to solve the problems in existing automotive bracket off-line inspection, such as the disconnect between working stress and assembly stress analysis, inaccurate identification of symmetry deviation, inability to trace the causes of anomalies, and lack of optimization closed loop, and to propose an automotive bracket off-line inspection method and system.

[0004] The objective of this invention can be achieved through the following technical solutions: In a first aspect, the present invention provides a method for detecting the off-line status of automotive brackets, comprising: S001: Real-time acquisition of the working data of the car bracket during the operation of the whole vehicle, and through data preprocessing and feature extraction, the set of working force points of the bracket is obtained; S002: Obtain the 3D model of the car bracket, perform structural and assembly analysis, obtain the force transmission path during the assembly process and in the static connection state, and generate a set of assembly force points. S003: Perform spatial mapping and mechanical coupling analysis on the set of working stress points of the bracket and the set of assembly stress points to obtain the coupling distribution model of key stress points; S004: Based on the key stress point coupling distribution model, the symmetry analysis of the working stress point and the assembly stress point is carried out to identify the stress difference and off-center loading of the left and right structures, and obtain the mirror stress deviation model. S005: Based on the mirror force deviation model and combined with the preset engineering standards, quantitative detection and analysis are carried out to calculate the deviation index and determine whether the bracket structure meets the design and safety requirements. S006: When the judgment result does not meet the standard, reverse tracing analysis is performed on the abnormal stress area to obtain the abnormal stress cause analysis result; S007: Based on the analysis results of abnormal stress causes, the structural parameters of the bracket are optimized and adjusted, and the comprehensive stress characteristic model is updated through iterative calculation, and the optimized bracket correction parameter set is output.

[0005] In a preferred embodiment of the present invention, the specific process of obtaining the set of working force points of the bracket through data preprocessing and feature extraction includes: Multi-source working data is processed for time synchronization and scale unification to establish a state field model that reflects the dynamic force evolution process of the bracket. Comprehensive force state quantities are defined for the discretized structural units. Neighborhood relationships are dynamically reconstructed according to the state evolution trend. The force propagation trend is judged based on the jump driving force and time accumulation. Local loops are avoided by path memory suppression. Structural units that are at the state peak position and located on the force propagation path are identified as the set of working force points of the bracket.

[0006] As a preferred embodiment of the present invention, the specific process of generating the assembly force point set includes: Structural semantic analysis is performed on the 3D model to divide it into structural units and assign connection type labels and assembly constraint attributes. The structural topology and assembly constraint relationships are extracted and transformed into constraint activation states. Constraint activation functions are established, assembly driving potentials are established, and variable connection relationships are generated through topology reconstruction. Path generation driving quantities are set and continuous activation criteria are applied to form a force transmission path sequence. Convergence modulation functions are set, and structural units that have reached a stable state of driving potential and are path convergence nodes are identified as the set of assembly force points.

[0007] As a preferred embodiment of the present invention, the specific process of performing spatial mapping and mechanical coupling analysis on the set of working stress points of the bracket and the set of assembly stress points includes: By mapping the assembly stress points to a unified coordinate system through a spatial compensation function, the working stress influence field and the assembly stress influence field are established respectively. A function is established to describe the synergistic enhancement and differential suppression of the two types of forces. Based on the spatial gradient of the coupled field, the force flow direction field and continuous evolution trajectory are established. A constraint modulation function is set to selectively enhance the coupled field. The spatial location with zero gradient and exhibiting local convergence characteristics is identified as the key stress point coupling distribution model.

[0008] As a preferred embodiment of the present invention, the specific process of performing symmetry analysis on the working stress point and the assembly stress point includes: The coupled force distribution is represented as a continuous function. A symmetric reference plane and a reflection operator are set for the bracket structure. The coupled force function is decomposed into symmetric and antisymmetric components. A global deviation functional is set to measure the degree of overall symmetry deviation. The antisymmetric components are expanded on orthogonal basis functions and the modal coefficients are weighted and corrected based on the assembly force influence field. Local maxima are identified based on the gradient of the deviation energy density and the Laplace operator to obtain the mirror force deviation model.

[0009] As a preferred embodiment of the present invention, the specific process of quantitative detection and analysis based on the mirror force deviation model combined with preset engineering standards includes: The deviation field corresponding to the mirror force deviation model is represented as a continuous function. The preset engineering standard is transformed into a comprehensive standard threshold function. A dimensionless deviation index function is established. The global deviation evaluation quantity, extreme deviation index and deviation exceeding limit volume fraction are calculated. A comprehensive judgment function is set and compared with the preset judgment threshold to determine whether the bracket structure meets the design and safety requirements.

[0010] As a preferred embodiment of the present invention, the specific process of performing reverse tracking analysis on the abnormal stress area when the determination result does not meet the standard includes: The set of spatial points with a normalized deviation index greater than 1 is extracted from the deviation field as the abnormal region. An inverse response function is established to associate the abnormal force with the structural geometric characteristic function, material property function and assembly error function. The geometric sensitivity, material sensitivity and assembly sensitivity are calculated respectively. After normalization, the dominant cause is determined according to the relative magnitude of each sensitivity, and the abnormal force cause analysis results are output.

[0011] As a preferred embodiment of the present invention, the specific process of optimizing and adjusting the bracket structure parameters and updating the comprehensive stress characteristic model through iterative calculation includes: The structural parameters of the bracket are uniformly represented as a parameter field. The contribution ratio of each factor in the abnormal stress cause analysis results is mapped to the parameter modulation weight and a comprehensive modulation driving force is set. The parameter evolution equation is established and the parameter constraint projection process is set to limit the updated parameters within the design allowable range. The updated structural parameters are re-input into the stress analysis model to calculate the new deviation index and comprehensive function. When the convergence condition is met, the optimized bracket correction parameter set is output.

[0012] Secondly, the present invention provides an automotive bracket off-line inspection system, comprising: a data acquisition module, a three-dimensional force module, a spatial coupling analysis module, a mirror deviation module, a quantitative standard module, an anomaly cause module, and an optimization iteration module. The data acquisition module acquires real-time working data of the car bracket during the vehicle's operation. Through data preprocessing and feature extraction, it generates a set of working force points of the bracket.

[0013] The 3D force module acquires the 3D model of the car bracket, combines the structural topology and assembly constraints to perform structural and assembly analysis, obtains the force transmission path during assembly and in static connection state, and generates a set of assembly force points.

[0014] The spatial coupling analysis module performs spatial mapping and mechanical coupling analysis on the set of working stress points of the bracket and the set of assembly stress points, establishes a stress point association model under a unified coordinate system, and outputs a key stress point coupling distribution model through load superposition, constraint matching and path transfer analysis.

[0015] The mirror deviation module is based on the key stress point coupling distribution model. It performs mirror mapping processing along the symmetrical reference plane of the bracket structure, performs symmetry analysis on the working stress point and the assembly stress point, identifies the stress difference and off-center loading of the left and right structures, and generates a mirror stress deviation model.

[0016] The quantitative standard module is based on the mirror force deviation model and combines preset engineering standards to perform quantitative detection and analysis, calculate deviation indexes, and determine whether the bracket structure meets design and safety requirements.

[0017] When the judgment result does not meet the standard, the abnormal force cause module performs reverse tracing analysis on the abnormal stress area, combines the structural geometric features, material distribution and assembly error sources to locate the root cause of the problem, and outputs the abnormal stress cause analysis results.

[0018] Based on the analysis results of abnormal stress causes, the optimization iteration module optimizes and adjusts the structural parameters of the bracket, and updates the comprehensive stress characteristic model through iterative calculation to realize the structural optimization closed loop and output the optimized bracket correction parameter set.

[0019] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention solves the problem of the disconnect between dynamic stress and static assembly constraints in existing off-line inspection methods by spatially mapping and mechanically coupling the working stress points under the vehicle's operating conditions with the assembly stress points in the three-dimensional model.

[0020] 2. During the testing process, this invention acquires real-time data on the load, vibration, acceleration, and connection reaction forces of the bracket, establishes a state field model, and identifies the set of working stress points of the bracket. It extracts the structural topological relationships and assembly constraint relationships, and generates a set of assembly stress points through constraint activation functions and assembly driving potentials. Based on this, a coupling analysis is performed to obtain a coupled distribution model of key stress points, and mirror mapping and antisymmetric decomposition are performed along the symmetry reference plane to identify the force differences and off-center loading conditions of the left and right structures. Further, quantitative testing and analysis are conducted in conjunction with preset engineering standards to calculate global deviation indices, extreme deviations, and excess volume fractions, comprehensively determining structural safety. When a non-compliance is determined, sensitivity analysis is performed on geometric features, material distribution, and assembly errors through an inverse response function to accurately locate the root cause of the anomaly. Finally, the plate thickness, stiffener layout, and connection point positions are optimized and adjusted based on the parameter evolution equation, and a structural optimization closed loop is achieved through iterative calculation.

[0021] 3. This invention upgrades the bracket off-line inspection from a static sampling inspection under a single working condition to an intelligent inspection process that integrates multiple sources, quantifies symmetry, traces the root cause, and optimizes the closed loop. This improves the accuracy of off-center load identification and the efficiency of structural optimization, while reducing the missed detection rate and rework costs. Attached Figure Description

[0022] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings.

[0023] Figure 1 This is a flowchart of the method steps of the present invention; Figure 2 This is a system block diagram of the present invention. Detailed Implementation

[0024] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] It should be understood that the terms “comprising” and “including” used in this disclosure and claims indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0026] It should also be understood that the terminology used in this disclosure is for the purpose of describing particular embodiments only and is not intended to limit the disclosure. As used in this disclosure and claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used in this disclosure and claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations. Example 1

[0027] Please see Figure 1 As shown, a method for detecting the off-line status of a car bracket includes: S001: Real-time acquisition of the vehicle bracket's working data during vehicle operation; through data preprocessing and feature extraction, identification of key stress areas and load concentration locations to obtain a set of working stress points for the bracket. The working data includes load, vibration, acceleration, and connection reaction forces.

[0028] S002; Obtain the 3D model of the vehicle bracket, and perform structural and assembly analysis by combining the structural topology and assembly constraints to obtain the force transmission paths during assembly and in static connection states, generating a set of assembly force points. The structural topology and assembly constraints include, for example, bolt connection points, welding points, and rubber bushing connection points.

[0029] S003: Perform spatial mapping and mechanical coupling analysis on the set of working stress points of the bracket and the set of assembly stress points, establish a stress point association model under a unified coordinate system, and obtain a key stress point coupling distribution model through load superposition, constraint matching and path transfer analysis.

[0030] S004: Based on the key stress point coupling distribution model, mirror mapping is performed along the symmetrical reference plane of the bracket structure. Symmetry analysis is performed on the working stress point and the assembly stress point to identify the stress difference and off-center loading of the left and right structures, and a mirror stress deviation model is obtained.

[0031] S005: Based on the mirror-image force deviation model and combined with preset engineering standards, quantitative detection and analysis are performed to calculate deviation indices and determine whether the bracket structure meets design and safety requirements. The preset engineering standards include structural strength standards, fatigue life standards, and assembly tolerance standards.

[0032] S006: When the judgment result does not meet the standard, reverse tracing analysis is performed on the abnormal stress area. Combining the structural geometric characteristics, material distribution and assembly error sources, the root cause of the problem is located and the abnormal stress cause analysis result is obtained.

[0033] S007: Based on the analysis results of abnormal stress causes, the structural parameters of the bracket are optimized and adjusted, and the comprehensive stress characteristic model is updated through iterative calculation to realize the structural optimization closed loop and output the optimized bracket correction parameter set.

[0034] The specific process of identifying key stress areas and load concentration locations through data preprocessing and feature extraction to obtain the set of working stress points of the bracket is as follows: After completing the multi-source data acquisition for the car bracket, the various data types are synchronized in time and standardized in scale to form a continuous and comparable data sequence under a unified time axis. This allows for the establishment of a state field model reflecting the dynamic stress evolution of the bracket, facilitating a comprehensive characterization of its stress behavior. Specifically, for the i-th structural unit after discretization of the bracket, the state variable is defined as: , where: z i (t) represents the comprehensive force state quantity of the i-th structural unit at time t; F i (t) represents the load signal at that unit; A i (t) represents the acceleration signal; V i (t) represents the vibration signal; R i (t) represents the connection reaction force signal; Δt represents the time integration window; This represents the time derivative operator. Let be the time integration variable, representing the instantaneous moment from t-Δt to t; through the above process, multi-source heterogeneous data is mapped into a unified state variable, resulting in the overall state field Z(t) of the bracket: , where N represents the total number of discrete units.

[0035] After obtaining the state field, the neighborhood relationships are dynamically reconstructed according to the state evolution trend. Specifically, the direction of state change is used as a criterion to establish a time-varying neighborhood set. , where: N i (t) represents the neighborhood set that forms an effective association with the i-th unit at time t; This represents the rate of change of state. It should be noted that the above condition means that there is a valid force transmission relationship between the two units only when the directions of state change of the two units are opposite.

[0036] After completing the neighborhood reconstruction, a neighborhood jump process is further established to drive the evolution of the force propagation path. The jump behavior is determined by establishing a continuously changing driving force function. Specifically, the jump driving force from structural element i to structural element j is defined as: ,in: This represents the jump driving force from structural unit i to structural unit j; Used to avoid tiny positive numbers with a denominator of zero.

[0037] After obtaining the jump driving force, the jump is determined by time accumulation. Specifically, at the current time t, if there exists a certain neighborhood structural unit j∈N i (t), satisfying: If the force propagation trend from structural unit i to structural unit j is considered to be valid, then a neighborhood jump is performed: i→j; Furthermore, during path generation, to prevent the force path from repeatedly looping within a local area, path memory is used to suppress over-processing; the computational unit accesses the memory function: , where: M i (t) represents the access memory strength of unit i at time t; i k The cell index representing historical access; t k This represents the corresponding access time; δ(·) represents the indicator function, when i=i k If the value is 1, then the value is 0; otherwise, the value is 0.

[0038] Based on the cell access memory function, the state variables are suppressed and corrected: This reduces the re-attraction of already visited areas, causing the force path to extend to new, high-response areas.

[0039] After completing the neighborhood jump and path evolution described above, the state changes along the path are analyzed. When a structural unit satisfies: When the force is at its peak, it indicates that the unit is in a state of peak, that is, the force changes from enhancement to attenuation, forming a force convergence point.

[0040] Finally, the set of structural units that meet the above conditions and are located on the force propagation path is defined as the set of working force points of the bracket: P={i|i satisfies the peak condition and is visited by the path}.

[0041] The specific process for generating the set of assembly force points is as follows: After obtaining the 3D model of the car bracket, structural semantic analysis is performed on the 3D model, transforming the geometric model from a simple shape representation into a structural expression that includes connection relationships and assembly attributes. Specifically, the bracket is divided into several structural units, and each structural unit is assigned a connection type label and assembly constraint attributes to form an initial structural set.

[0042] After discretizing the structure, the structural topological relationships and assembly constraints are further extracted. These assembly constraints include bolt connections, welded joints, and rubber bushing connections. These constraints are then transformed into constraint activation states to describe the dynamic participation of the connections during assembly.

[0043] Constraint activation state establishment: For the i1th structural element, the constraint activation function is defined as follows: , where: a i1 (t) represents the constraint activation strength of structural element i at time t; M i1 Indicates the number of constraints associated with structural unit i1; κ m This represents the type weight factor for the m-th type of constraint, used to distinguish the importance of bolts, welds, bushings, etc., in force transmission. For example: bolted connections have high stiffness, so κ=1.0; welded connections have κ=0.8; and rubber bushings have κ=0.5. m (i1) represents a binary indicator function that determines whether structural element i1 has the m-th type of constraint: if it does, m (i1)=1; otherwise, m (i1)=0. This converts connection points in the geometric model into computable Boolean symbols, avoiding the inclusion of non-existent constraints in activation strength calculations. χ m (t) is the constraint activation timing function, indicating whether the constraint is active during the assembly process.

[0044] After obtaining the constrained activation state, in order to avoid directly using stress or stiffness analysis, the potential transmission trend of force in the structure is described by matching the driving potential function.

[0045] The assembly driving potential establishment process is defined as follows: , where: u i1 (t) represents the assembly driving potential σ of structural unit i1. i1The complexity of a structural element i1 in the topology is typically defined as the number of constraint branches connected to that element. For example, a weld point connecting three components has 3 branches, σ=3; an isolated unconnected point has σ=0. ​​In the assembly driving potential u... i1 In (t), the penalty term (-η·σ_i1) is used to avoid excessive concentration of force path on complex nodes; η and ω are adjustment coefficients used to balance the weights of different terms in the assembly driving potential: preferably: η=0.1, ω=0.05; This represents the rate of change of constraint activation.

[0046] After obtaining the driving potential, variable connectivity is generated through a topology reconstruction process. Specifically, a topology reconstruction function is established, defining the potential connection strength between structural units as follows: , where: Θ i1j1 (t) represents the potential connection strength between structural units i1 and j1; The structure numbering difference is represented (used to weaken direct associations over long distances); ρ represents the attenuation coefficient. Based on this, the dynamic topological relationship is defined as: E(t)={(i1,j1)∣Θ i1j1 (t)>0}. When the strength is greater than 0, it is determined that there is an effective topological connection between the two units, transmitting assembly force.

[0047] After completing the topology reconstruction, the force path generation process during assembly is further established. A path self-generation process is set up, and the path generation driving variables are defined: , where: H i1→j1 (t) represents the driving quantity generated by the path from i1 to j1; It is a tiny positive number. And a continuous activation criterion is applied: When the above conditions are met, a path connection is established in the topology set E(t): And gradually form a path sequence: Π={i11, i12, ..., i1 L}

[0048] After assembly, set the convergence modulation function: ,in: The term represents the driving potential after convergence; λ is the convergence coefficient, used to control the driving potential after assembly. The rate of decay over time. A larger λ indicates a faster decay, meaning the localized stress caused by assembly quickly reaches a steady state after settling. The preferred λ value is 0.1 s. -1 .

[0049] Next, the stress points of the assembly are identified, and the stress points of the assembly are defined to satisfy the following: Where: the first condition indicates that the driving potential has reached a stable state; the second condition indicates that the assembly force point is a path convergence node. The final set of assembly force points is: Q = {i1 | i1 satisfies the above conditions}.

[0050] The specific process of performing spatial mapping and mechanical coupling analysis on the set of working stress points of the bracket and the set of assembly stress points is as follows: After obtaining the set of working stress points P and the set of assembly stress points Q for the bracket, a unified spatial representation of the two types of stress points is performed. Since the working stress points originate from actual operational data, while the assembly stress points originate from the structural model, there are differences in their coordinate references and assembly postures. Therefore, a spatial compensation function is established to correct the assembly stress points, mapping them to a unified coordinate system, thus obtaining the mapped assembly stress points q′. j2 Its expression is: , where W(·) represents the spatial compensation function, which describes the position correction amount caused by assembly errors.

[0051] After achieving spatial unification, the discrete force points are transformed into an influence distribution in continuous space, avoiding interference from local matching errors on the overall analysis. Specifically, the working force influence field Φ is established based on the set of working force points. P (x) is used to establish the assembly force influence field Φ based on the mapped assembly force points. Q (x), which are respectively represented as: Where x is a vector at any position in space, the discrete force points in the formula are extended to a continuous influence distribution, providing a unified expression for subsequent coupling analysis.

[0052] After obtaining the two types of force influence fields, a coupling function Ψ(x) is established to describe the synergistic enhancement and differential suppression of the two types of forces, which is expressed as: Where ζ is an adjustment coefficient, balancing the influence of force consistency and difference; the larger ζ is, the more emphasis is placed on the consistency of the two types of forces; the smaller ζ is, the more differences are allowed. The preferred ζ = 0.5. This coupling function forms a continuous distribution in space reflecting the degree of force coordination.

[0053] Building upon this, the force transmission trend within the structure is further reflected, and the force transmission direction is established based on the spatial variation characteristics of the coupled field. Specifically, the force flow direction field is obtained by performing spatial gradient calculations on the coupling function. : Where ∇ represents the gradient operator, and G(x) represents the direction of force evolution in space. A continuous evolution trajectory is established along this direction: The resulting trajectory reflects the natural transmission path of force under the combined action of working conditions and assembly constraints.

[0054] Furthermore, to match the aforementioned path transmission process with assembly constraint characteristics, a constraint modulation function is set to selectively enhance the coupling field. The constraint modulation function is defined as follows: ,in, This is a threshold parameter used to distinguish between the effective and ineffective constraint regions. When the assembly is subjected to force field Φ... Q (x)> When Γ(x) approaches 1, the coupled field is preserved; Φ Q (x) < When Γ(x) approaches 0, the coupling field is suppressed. This enhances the stress analysis in regions with strong assembly constraints and suppresses it in weak regions. Typical value: τ = 0.3, calibrated according to the assembly field distribution. By applying this modulation function to the coupling field, the corrected coupling distribution is obtained: This strengthens the stress analysis results in the constrained assembly region and suppresses them in the weaker constrained region.

[0055] After completing the coupled field correction, key force locations are identified by analyzing their spatial stability. A spatial location is considered a force convergence point when its gradient is zero and it exhibits local convergence characteristics. The criterion is as follows: , where λ max This represents the largest eigenvalue of the corresponding Hessian matrix, used to determine if the point is a stable convergence region.

[0056] Finally, all spatial locations that meet the above conditions are used to form a key force point coupling distribution model C.

[0057] The specific process of performing a symmetry analysis on the working stress point and the assembly stress point is as follows: After obtaining the coupling distribution model C of the key stress points, its corresponding coupling stress distribution is first uniformly represented as a continuous function Ψ′(x) defined on the bracket structure domain Ω. Here, Ψ′(x) is derived from the result of coupling the aforementioned working stress influence field and the assembly stress influence field and being constrained and modulated, and is used to characterize the comprehensive stress intensity at spatial position x.

[0058] To conduct symmetry analysis, a symmetry reference plane JJ is established for the bracket structure. This reference plane is determined by the structural design and is expressed as follows: Where n0 originates from the symmetrical normal direction in the bracket design, and x0 originates from the center point of the symmetry of the reference surface; together, they determine the symmetrical reference.

[0059] Based on this, a spatially symmetric mapping is performed, and a reflection operator R(·) is set to map any point x to its mirror position about the reference plane. Its expression is: .

[0060] After completing the mirror mapping, symmetry decomposition is performed directly at the continuous function level; specifically, the coupled force function Ψ′(x) is decomposed into symmetric and antisymmetric components: , , among which, Ψ s (x) represents the common force characteristics of the left and right structures; Ψ a (x) represents the degree of symmetry breaking.

[0061] After obtaining the antisymmetric components, a global deviation functional is set to measure the degree of deviation from the overall symmetry, which is expressed as: Where J0 is the overall off-center load level; Furthermore, a set of orthogonal basis functions {φ} defined on the structural domain are set. k (x)}, the basis functions are derived from the function expansion system of the structure domain (such as the orthogonal function system or the characteristic function system), and the antisymmetric components are expanded as follows: Where, the expansion coefficient α k Defined as: The projection intensity of the symmetric component onto the corresponding basis function characterizes the degree of symmetry breaking under different spatial modes.

[0062] After obtaining the modal expansion, the assembly force influence field Φ is set. Q (x), derived from the continuous influence distribution established by the set of assembly stress points, reflects the strength of assembly constraint effects. Based on this, the modal coefficients are weighted and corrected: ,in, This indicates the intensity of the deviation mode after considering assembly constraints, thus enhancing the expression of deviations in assembly-sensitive areas.

[0063] After completing the modal correction, an energy-based criterion is set. The deviation energy density function is defined as: , where E(x) is derived from the square of the antisymmetric component and is used to characterize the intensity of local symmetry breaking.

[0064] When a certain position satisfies: =0 and When < 0, it indicates that the location is a local maximum of energy, where the gradient The Laplace operator is derived from the first-order rate of change of the energy function. It originates from the characteristics of second-order spatial variation and is used to determine whether it is a local convergence region.

[0065] Finally, all modes that satisfy the above energy extremum condition and have corresponding modified mode coefficients α are... k The spatial location set of ′ is defined as the mirror force deviation model M: M={x∈Ω|x satisfies the energy extremum condition and mode}, which is used to describe the symmetry failure distribution and off-center load characteristics of the bracket under the coupled action of working force and assembly constraint.

[0066] The quantitative detection and analysis based on the mirror-image force deviation model, combined with preset engineering standards, is carried out in the following specific process: After obtaining the mirror-image force deviation model M, its corresponding deviation field is represented as a continuous function Δ′(x) defined on the structural domain Ω. Here, Δ′(x) is derived from the antisymmetric component Ψ obtained by the aforementioned symmetric decomposition. a (x) and the influence field of assembly constraints Φ Q The modulation result of (x) is used to characterize the effective force deviation intensity at spatial location x.

[0067] The pre-defined engineering standards are transformed into calculable constraint expressions. Engineering standards include structural strength standards, fatigue life standards, and assembly tolerance standards, all of which essentially boil down to limitations on allowable deviation levels. Based on this, a standard constraint function S(x) is set to characterize the maximum allowable deviation capability at position x, expressed as: S(x) = min(S... str (x), S fat (x), S tol (x)), where: S(x) represents the comprehensive standard threshold function; S str (x) represents the upper limit of the allowable deviation derived from the structural strength standard; S fat (x) represents the upper limit of the allowable deviation derived from the fatigue life standard; S tol (x) represents the allowable deviation range derived from the assembly tolerance standard.

[0068] After obtaining the standard constraint function, the deviation field is compared with the standard to establish a dimensionless deviation index function: Where: D(x) represents the normalization deviation index; Based on this, to avoid instability caused by relying solely on single-point judgments, a holistic measurement of the deviation index is performed. The global deviation evaluation metric is defined as follows: , where D global The square integral of the normalized deviation index reflects the degree of cumulative deviation within the overall structural range.

[0069] Furthermore, to identify localized risk areas, an extreme value deviation index is set: Extreme value deviation index This represents the maximum response in the deviation field, used to reflect the most unfavorable stress location.

[0070] Next, to take into account spatial distribution characteristics, a volume fraction exceeding the deviation limit is set: , where: V ex Ω represents the proportion of the overlimit region; |Ω| represents the volume of the structural domain; H(·) is the step function, which takes the value 1 when D(x) > 1, and 0 otherwise.

[0071] After obtaining the above-mentioned deviation indicators, a comprehensive judgment function is set: Where: F is a comprehensive index; ω1, ω2, and ω3 are weighting coefficients, reflecting the importance of overall deviation, local extreme values, and out-of-limit ranges. The weights are derived from the degree of attention given to different risk types in the engineering design. Example values: ω1=0.3, ω2=0.5, ω3=0.2.

[0072] Finally, the comprehensive index is compared with the preset judgment threshold F. th Comparison: when F ≤ F th If the condition is met, the bracket structure is deemed to meet the design and safety requirements; otherwise, the structure is considered to have an off-center load risk.

[0073] When the judgment result does not meet the standard, a reverse tracing analysis is performed on the abnormal stress area, specifically including: Based on the aforementioned mirror force deviation model, reverse tracing analysis is performed on the abnormal area to locate the structural root cause of the deviation.

[0074] Specifically, outlier regions are extracted from the deviation field Δ′(x). An outlier region is defined as the set of spatial points that satisfy the normalized deviation index D(x) > 1. , where Ω abn This indicates the spatial region where the deviation exceeds the engineering standard, derived from the comparison results between the aforementioned deviation index function and the standard constraint function.

[0075] After identifying the anomalous region, to avoid relying on local neighborhood expansion, the anomalous region is further mapped back to the coupled force field and assembly constraint field. An inverse response function is established to describe the reverse correlation between the anomalous force and structural properties. The inverse response function is: Where R0(x) represents the inverse response intensity.

[0076] Based on this, an abnormal stress is correlated with the structural geometric features. By setting the structural geometric feature function G0(x), which originates from local geometric properties in the 3D model, such as thickness variation, curvature, and number of connection branches, a geometric sensitivity expression is established. , among which, S g This indicates the degree to which geometric factors contribute to abnormal forces.

[0077] Furthermore, a material property function M(x) is set, derived from material distribution information such as elastic modulus or material zoning, and material sensitivity is defined: , among which, S m This indicates the degree to which material factors affect abnormal deviations.

[0078] Meanwhile, to characterize the sources of assembly errors, an assembly error function E0(x) is set, originating from the distribution of assembly offset, clearance, or connection errors, and an assembly sensitivity is defined: , among which, S e This indicates the degree to which assembly errors contribute to abnormal stress.

[0079] After obtaining the above multi-source sensitivity, normalization is performed: (Processed) ,in, These represent the relative contribution ratios of geometric, material, and assembly factors, respectively.

[0080] Subsequently, the causes of abnormal forces are determined based on the relative magnitudes of the sensitivities. When the normalized sensitivity corresponding to a certain factor is the highest, that factor is considered the primary cause. For example, when... At its maximum, it corresponds to local geometric problems, such as insufficient stiffness or abrupt structural changes; when At its maximum, this corresponds to uneven material distribution or insufficient performance; when At its maximum, it corresponds to assembly errors, such as connection point offset or welding deformation.

[0081] Finally, the above analysis results are output as the abnormal force cause analysis results: A={dominant cause type, corresponding spatial location, influence weight}, where A is used to characterize the source category, occurrence location and influence degree of abnormal force.

[0082] The process of optimizing and adjusting the bracket structure parameters and updating the comprehensive stress characteristic model through iterative calculation is as follows: After obtaining the abnormal stress cause analysis result A, a targeted optimization is performed, transforming the cause result into a continuous modulation process of structural parameters, establishing a cause-driven parameter update process. Specifically, the structural parameters of the bracket are uniformly represented as a parameter field P(x) defined on the structural domain Ω, where: P(x) = {t(x), r(x), c(x)}, where: t(x) represents the local plate thickness distribution, derived from structural geometric parameters; r(x) represents the density of stiffeners or structural reinforcement layout, derived from structural topology design; c(x) represents the connection point location, derived from the assembly structure definition. The above parameter field uniformly describes the adjustable design variables of the bracket structure.

[0083] Based on this, the contribution ratio of each factor in the abnormal stress cause analysis results will be calculated. The mapping is used as parameter modulation weights to guide the adjustment direction of different parameters. For this purpose, the parameter response function is set as: U(x) = ·G0(x)+ ·M(x)+ E(x), where U(x) represents the overall modulation driving force.

[0084] After obtaining the modulation driving force, the parameter evolution equation is set and the evolution is performed: ,in: This represents the rate of change of the parameter as the iteration process progresses; This indicates the trend of the structural performance error function with respect to the parameters. Derived from the aforementioned deviation indicators (such as F or D) global ( ), used to measure the degree of deviation of the current structural performance.

[0085] Furthermore, the parameter constraint projection process is set to limit the updated parameters within the design's allowable range. Definition: ,in: Indicates the parameters after projection; Represents the projection operator; C p This is a set of design constraints, such as minimum plate thickness and maximum connection spacing.

[0086] After updating the parameters, the updated structural parameters are re-input into the aforementioned force analysis model to establish a new coupled force field Ψ′(k1), and the deviation index and comprehensive function F are recalculated accordingly. (k1) .

[0087] When the convergence condition is met: Or: F (k1) ≤F th When δ is reached, the structural optimization process is considered to have reached a stable state, where δ is the convergence threshold and k1 represents the number of iterations.

[0088] Finally, the converged parameter field As the output of the optimization result, it is further extracted into a design scheme that can be used in engineering: O = {optimized plate thickness distribution, stiffener layout scheme, and connection point correction position}. The output result includes both continuous parameter distribution and can be converted into discrete engineering design parameters. Example 2

[0089] Please see Figure 2 As shown, an off-line inspection method for automobile brackets includes: a data acquisition module, a three-dimensional force module, a spatial coupling analysis module, a mirror deviation module, a quantitative standard module, an anomaly cause module, and an optimization iteration module; The data acquisition module acquires real-time operational data of the vehicle bracket during vehicle operation, including load, vibration, acceleration, and connection reaction force. Multi-source operational data undergoes time synchronization and scale unification processing to establish a state field model reflecting the dynamic force evolution of the bracket. For the discretized structural units, a comprehensive force state quantity is defined. Neighborhood relationships are dynamically reconstructed based on state evolution trends. Force propagation trends are determined based on jump driving forces and time accumulation. Path memory suppression avoids local loops. Finally, structural units at state peak positions and located on the force propagation path are identified, generating a set of operational force points for the bracket.

[0090] The 3D force module acquires the 3D model of the car bracket, performs structural semantic analysis on the 3D model, divides the structural units, and assigns connection type labels and assembly constraint attributes. It extracts the structural topological relationships and assembly constraint relationships, including bolt connection points, weld points, and rubber bushing connection points. These constraint relationships are transformed into constraint activation states, and constraint activation functions are established to create assembly driving potentials. Variable connection relationships are generated through topological reconstruction, and path generation driving quantities are set, with continuous activation criteria used to form a force transmission path sequence. A convergence modulation function is set to identify structural units whose driving potentials have reached a stable state and are path convergence nodes, generating a set of assembly force points.

[0091] The spatial coupling analysis module performs spatial mapping and mechanical coupling analysis on the set of working stress points and the set of assembly stress points of the bracket. A spatial compensation function maps the assembly stress points to a unified coordinate system, establishing working stress influence fields and assembly stress influence fields respectively. A coupling function is established to describe the synergistic enhancement and differential suppression of the two types of forces. Based on the spatial gradient of the coupling field, a force flow direction field and a continuous evolution trajectory are established. A constraint modulation function is set to selectively enhance the coupling field, identifying spatial locations with zero gradients and exhibiting local convergence characteristics, and outputting a coupling distribution model of key stress points.

[0092] The mirror deviation module is based on the key stress point coupling distribution model. It represents the coupled stress distribution as a continuous function, sets the symmetry reference plane and reflection operator of the bracket structure, and decomposes the coupled stress function into symmetric and antisymmetric components. It sets a global deviation functional to measure the degree of overall symmetry deviation, expands the antisymmetric components on orthogonal basis functions and performs weighted correction on the modal coefficients based on the assembly stress influence field, and identifies local maxima based on the gradient of the deviation energy density and the Laplace operator to generate the mirror stress deviation model.

[0093] The quantitative standard module is based on the mirror force deviation model, which represents the deviation field as a continuous function and transforms the preset engineering standards into a comprehensive standard threshold function. The preset engineering standards include structural strength standards, fatigue life standards, and assembly tolerance standards. A dimensionless deviation index function is established to calculate the global deviation evaluation quantity, extreme deviation index, and deviation exceeding the limit volume fraction. A comprehensive judgment function is set and compared with the preset judgment threshold to determine whether the bracket structure meets the design and safety requirements.

[0094] When the judgment result does not meet the standard, the anomaly cause module extracts the set of spatial points with a normalized deviation index greater than 1 from the deviation field as the anomaly region, establishes an inverse response function to associate the abnormal force with the structural geometric characteristic function, material property function and assembly error function, and calculates the geometric sensitivity, material sensitivity and assembly sensitivity respectively; after normalization processing, the dominant cause is determined according to the relative magnitude of each sensitivity, and the anomaly force cause analysis result is output.

[0095] The optimization iteration module, based on the abnormal stress cause analysis results, uniformly represents the bracket structure parameters as a parameter field, which includes local plate thickness distribution, stiffener layout density, and connection point location. It maps the contribution ratio of each factor in the abnormal stress cause analysis results to parameter modulation weights and sets a comprehensive modulation driving force. It establishes parameter evolution equations and sets parameter constraint projection processes to limit the updated parameters within the design allowable range. The updated structural parameters are re-input into the stress analysis model to calculate new deviation indices and comprehensive functions. When the convergence condition is met, the optimized bracket correction parameter set is output.

[0096] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to any specific implementation. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for detecting the off-line status of an automobile bracket, characterized in that, include: Real-time acquisition of the working data of the car bracket during the operation of the whole vehicle; through data preprocessing and feature extraction, the set of working stress points of the bracket is obtained. Obtain the 3D model of the car bracket, perform structural and assembly analysis, obtain the force transmission path during assembly and in static connection state, and generate a set of assembly force points. Spatial mapping and mechanical coupling analysis were performed on the set of working stress points of the bracket and the set of assembly stress points to obtain a coupling distribution model of key stress points. Based on the key stress point coupling distribution model, the symmetry analysis of the working stress point and the assembly stress point is carried out to identify the stress difference and off-center loading of the left and right structures, and to obtain the mirror stress deviation model. Based on the mirror force deviation model and combined with the preset engineering standards, quantitative detection and analysis are carried out to calculate the deviation index and determine whether the bracket structure meets the design and safety requirements. When the judgment result does not meet the standard, reverse tracing analysis is performed on the abnormal stress area to obtain the abnormal stress cause analysis result. Based on the analysis of the causes of abnormal stress, the structural parameters of the bracket are optimized and adjusted, and the comprehensive stress characteristic model is updated through iterative calculation to output the optimized bracket correction parameter set.

2. The method for detecting the off-line status of an automobile bracket according to claim 1, characterized in that, The specific process of obtaining the set of working stress points of the bracket through data preprocessing and feature extraction includes: Multi-source working data is processed for time synchronization and scale unification to establish a state field model that reflects the dynamic force evolution process of the bracket. Comprehensive force state quantities are defined for the discretized structural units. Neighborhood relationships are dynamically reconstructed according to the state evolution trend. The force propagation trend is judged based on the jump driving force and time accumulation. Local loops are avoided by path memory suppression. Structural units that are at the state peak position and located on the force propagation path are identified as the set of working force points of the bracket.

3. The method for detecting the off-line status of a car bracket according to claim 2, characterized in that, The specific process of generating the set of assembly stress points includes: Structural semantic analysis is performed on the 3D model to divide it into structural units and assign connection type labels and assembly constraint attributes. The structural topology and assembly constraint relationships are extracted and transformed into constraint activation states. Constraint activation functions are established, assembly driving potentials are established, and variable connection relationships are generated through topology reconstruction. Path generation driving quantities are set and continuous activation criteria are applied to form a force transmission path sequence. Convergence modulation functions are set, and structural units that have reached a stable state of driving potential and are path convergence nodes are identified as the set of assembly force points.

4. The method for detecting the off-line status of an automobile bracket according to claim 1, characterized in that, The specific process of performing spatial mapping and mechanical coupling analysis on the set of working stress points of the bracket and the set of assembly stress points includes: By mapping the assembly stress points to a unified coordinate system through a spatial compensation function, the working stress influence field and the assembly stress influence field are established respectively. A function is established to describe the synergistic enhancement and differential suppression of the two types of forces. Based on the spatial gradient of the coupled field, the force flow direction field and continuous evolution trajectory are established. A constraint modulation function is set to selectively enhance the coupled field. The spatial location with zero gradient and exhibiting local convergence characteristics is identified as the key stress point coupling distribution model.

5. The method for detecting the off-line status of an automobile bracket according to claim 4, characterized in that, The specific process of performing symmetry analysis on the working stress point and the assembly stress point includes: The coupled force distribution is represented as a continuous function. A symmetric reference plane and a reflection operator are set for the bracket structure. The coupled force function is decomposed into symmetric and antisymmetric components. A global deviation functional is set to measure the degree of overall symmetry deviation. The antisymmetric components are expanded on orthogonal basis functions and the modal coefficients are weighted and corrected based on the assembly force influence field. Local maxima are identified based on the gradient of the deviation energy density and the Laplace operator to obtain the mirror force deviation model.

6. The method for detecting the off-line status of a car bracket according to claim 5, characterized in that, The specific process of quantitative detection and analysis based on the mirror force deviation model combined with preset engineering standards includes: The deviation field corresponding to the mirror force deviation model is represented as a continuous function. The preset engineering standard is transformed into a comprehensive standard threshold function. A dimensionless deviation index function is established. The global deviation evaluation quantity, extreme deviation index and deviation exceeding limit volume fraction are calculated. A comprehensive judgment function is set and compared with the preset judgment threshold to determine whether the bracket structure meets the design and safety requirements.

7. The method for detecting the off-line status of an automobile bracket according to claim 1, characterized in that, When the judgment result does not meet the standard, the specific process of performing reverse tracing analysis on the abnormal stress area includes: The set of spatial points with a normalized deviation index greater than 1 is extracted from the deviation field as the abnormal region. An inverse response function is established to associate the abnormal force with the structural geometric characteristic function, material property function and assembly error function. The geometric sensitivity, material sensitivity and assembly sensitivity are calculated respectively. After normalization, the dominant cause is determined according to the relative magnitude of each sensitivity, and the abnormal force cause analysis results are output.

8. The method for detecting the off-line status of an automobile bracket according to claim 7, characterized in that, The specific process of optimizing and adjusting the bracket structure parameters and updating the comprehensive stress characteristic model through iterative calculation includes: The structural parameters of the bracket are uniformly represented as a parameter field. The contribution ratio of each factor in the abnormal stress cause analysis results is mapped to the parameter modulation weight and a comprehensive modulation driving force is set. The parameter evolution equation is established and the parameter constraint projection process is set to limit the updated parameters within the design allowable range. The updated structural parameters are re-input into the stress analysis model to calculate the new deviation index and comprehensive function. When the convergence condition is met, the optimized bracket correction parameter set is output.

9. A vehicle bracket off-line inspection system, characterized in that... A method for detecting off-line inspection of a car bracket as described in any one of claims 1-8 includes: a data acquisition module, a three-dimensional force module, a spatial coupling analysis module, a mirror deviation module, a quantitative standard module, an anomaly cause module, and an optimization iteration module; The data acquisition module acquires the working data of the car bracket during the operation of the whole vehicle in real time, and generates a set of working force points of the bracket through data preprocessing and feature extraction; The 3D force module acquires the 3D model of the car bracket, combines the structural topology and assembly constraints to perform structural and assembly analysis, obtains the force transmission path during assembly and in static connection state, and generates a set of assembly force points. The spatial coupling analysis module performs spatial mapping and mechanical coupling analysis on the set of working stress points of the bracket and the set of assembly stress points, establishes a stress point association model under a unified coordinate system, and outputs a coupling distribution model of key stress points through load superposition, constraint matching and path transfer analysis. The mirror deviation module is based on the key stress point coupling distribution model. It performs mirror mapping processing along the symmetrical reference plane of the bracket structure, performs symmetry analysis on the working stress point and the assembly stress point, identifies the stress difference and off-center loading of the left and right structures, and generates a mirror stress deviation model. The quantitative standard module is based on the mirror force deviation model, combined with preset engineering standards to perform quantitative detection and analysis, calculate deviation index, and determine whether the bracket structure meets the design and safety requirements. When the judgment result of the anomaly cause module does not meet the standard, it performs reverse tracing analysis on the abnormal stress area, combines the structural geometric features, material distribution and assembly error sources to locate the root cause of the problem, and outputs the abnormal stress cause analysis results. Based on the analysis results of abnormal stress causes, the optimization iteration module optimizes and adjusts the structural parameters of the bracket, and updates the comprehensive stress characteristic model through iterative calculation to realize the structural optimization closed loop and output the optimized bracket correction parameter set.

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