Wire harness whole-process motion simulation method based on CATIA

Abstract

The invention belongs to the field of CAE (Computer Aided Engineering) engineering simulation and the technical field of electrical interconnection system engineering, and particularly relates to a CATIA (Computer Aided Three-dimensional Interactive Application)-based wire harness whole-process motion simulation method, which comprises the following steps of: 1) constructing a motion mechanism simulation model; 2) defining main attributes influencing the movement of the wire harness; 3) establishing a wire harness simulation model; 4) based on the wire harness simulation model, simulating the wire harness on the movement mechanism, updating the wire harness simulation model in real time, and meanwhile, selecting an extreme state section for conformity analysis in each time form of a movement wire harness section; and 5) if the conformity analysis is passed, outputting the picture containing the wire harness simulation model at each moment, regenerating the screenshot under the fixed visual angle into a video through video synthesis software, and if the conformity analysis is not passed, returning to the step 2). The method is suitable for complex movement, and analysis results of the length, the shape, the bending degree, the stretching, the stress concentration point and the like of the wire harness in the movement process can be more visually output.

Description

Technical Field

[0001] The invention belongs to the field of CAE engineering simulation and the technical field of electrical interconnection system engineering, and is specifically a method for simulating the whole process motion of a wiring harness based on CATIA. Background Art

[0002] As the neural network of the whole machine, the wiring harness plays an important role in power supply and signal transmission. When the wiring harness is fixedly connected to the moving parts, how to ensure that the follow-up wiring harness is not damaged and functions intact during the movement, and does not interfere with the moving components and surrounding parts, is the main problem that needs to be solved in the design of the follow-up wiring harness product. As a product under the electrical interconnection system (EWIS), the wiring harness is the last to be integrated and the first to be delivered compared to other systems, and the schedule pressure is high. Therefore, it is extremely necessary to use computer engineering simulation technology to quickly and efficiently define feasible solutions in the product design stage.

[0003] The "double limit method" used in current existing technologies is the mainstream technical method, which is to use computer engineering software to design the wire harness product in the initial state and final state of the motion mechanism, compare the difference between the two results, and finally infer the motion process of the wire harness following the mechanism based on engineering experience and mechanism layout, and use this as a technical basis for evaluation. However, this method has the following problems:

[0004] 1. It is suitable for relatively simple sports. For complex sports, the evaluation results will deviate greatly;

[0005] 2. There is stress on the harness, and it is impossible to determine whether the harness will be damaged due to excessive bending during movement;

[0006] The above technology does not provide intuitive feedback on the harness situation during the motion process. Therefore, a harness full-process motion simulation method is urgently needed to solve the existing technical problems. Summary of the invention

[0007] The purpose of the present invention is to provide a method for simulating the whole process motion of a wire harness based on CATIA. Through computer engineering software, the whole motion state of the wire harness can be simulated, that is, the state change of the wire harness as the process progresses can be simulated, and each instantaneous state of the wire harness can be intuitively displayed. Based on this, the bending, stress and interference of the wire harness are analyzed. The present invention solves the technical difficulties that the prior art cannot realize the whole process simulation of the wire harness, solves the technical difficulties that the prior art cannot intuitively output a certain instantaneous state during the motion process, and solves the technical difficulties that the prior art cannot judge the bending and stress conditions of the wire harness during the motion process.

[0008] The technical solution adopted by the present invention to achieve the above-mentioned purpose is: a CATIA-based harness full-process motion simulation method, comprising the following steps:

[0009] 1) Construct a motion mechanism simulation model;

[0010] 2) Define the main properties that affect the motion of the cable harness, including cable composition, diameter, length, stiffness, and minimum allowable bend radius;

[0011] 3) Establish a harness simulation model based on the motion mechanism simulation model and the defined main properties;

[0012] 4) Based on the harness simulation model, simulate the harness on the motion mechanism and update the harness simulation model in real time. At the same time, select the most extreme state segment in each time form of the motion harness segment for compliance analysis;

[0013] 5) If the conformity analysis is passed, the images of each moment of the harness simulation model are output, and the screenshots under a fixed viewing angle are regenerated into a video through video synthesis software. If the conformity analysis is not passed, return to step 2).

[0014] The step 1) comprises the following steps:

[0015] 1-1) Define and divide motion components:

[0016] Analyze the transmission principle of the motion mechanism, define each transmission unit, and divide the parts that constitute the motion mechanism into corresponding transmission units;

[0017] 1-2) Each moving component subassembly:

[0018] According to the division results of the moving components, the parts contained in each moving component are identified and assembled into subassemblies;

[0019] 1-3) General assembly of motion mechanism:

[0020] Assemble all moving components into a moving mechanism, and define the transmission and constraints between the moving components;

[0021] 1-4) Motion simulation:

[0022] Define the fixed components and driving pairs; after the definition is completed, calculate the degrees of freedom of the motion mechanism, and when the degrees of freedom are 0, the mechanism performs simulation.

[0023] The step 1-1) is specifically:

[0024] Determine the energy transfer path and motion conversion mode of each transmission unit in the motion mechanism, and identify each link from power input to the final execution of the action;

[0025] The motion mechanism is abstracted into nodes, i.e., individual parts; the edges represent the connection and motion transmission relationship between the parts; the network structure is composed through topological analysis, and different transmission units are determined by traversing and analyzing the network;

[0026] The parts are divided according to their direct association and functional coordination in the transmission process, and an association matrix is ​​established. The rows of the matrix correspond to the parts, and the columns correspond to the transmission units that have been preliminarily determined. By analyzing the assembly relationship and motion transmission matching conditions between the parts, if the part participates in the motion transmission of a certain transmission unit, the corresponding matrix element position is marked as 1, otherwise it is marked as 0. Finally, the accurate division of parts to transmission units is completed based on the association matrix.

[0027] The steps 1-4) are specifically:

[0028] (1) Define the fixed component and the driving pair:

[0029] Components that remain unchanged relative to the earth or reference coordinate system during the entire motion process are marked as fixed components by analyzing the supporting structure and working status of the mechanism, and their positions and postures are set to be fixed in the model;

[0030] Combined with the power input of the mechanism, determine the kinematic pair that provides active motion; according to the motion characteristics of the power source, including: the speed and torque curve of the motor, the stroke and thrust curve of the cylinder, set the motion parameters of the driving pair, and use a function expression to describe the change of the motion of the driving pair over time;

[0031] (2) Algorithm for calculating the degrees of freedom of the motion mechanism:

[0032] Based on the degree of freedom calculation, for a planar mechanism, the degrees of freedom are:

[0033] F=3n-2P L -P H

[0034] Where n is the number of active components, P L For low pair number, P H It is the high vice number;

[0035] For spatial mechanisms, the degrees of freedom are calculated according to the corresponding extended degree of freedom calculation formula.

[0036] The step 2) comprises the following steps:

[0037] 2-1) Define the cable model of the integrated harness: determine the cable types inside the harness, including single wire, twisted wire, shielded wire, coaxial and Ethernet; and determine the specifications and quantity of each wire;

[0038] 2-2) Determine the outer diameter of the wire harness according to the empirical formula; then define the wire harness stiffness and determine the minimum allowable bending radius of the wire harness;

[0039] 2-3) Define the laying path and determine the length.

[0040] The steps 2-3) are specifically:

[0041] 2-3-1) Based on the connector interface corresponding to the motion mechanism simulation model, determine its coordinate position in the model space; according to the layout of the components, use the path planning algorithm to determine the laying path of the wire harness; abstract the motion mechanism simulation model into a graph structure, with nodes representing key component positions and connector interfaces, and edges representing feasible laying channels. With the starting connector interface as the starting point and the target connector interface as the end point, search for the shortest laying path;

[0042] During the search process, the restrictions imposed by the geometric shape of the moving component on the path are considered, and the collision detection algorithm is used to determine whether the harness path interferes with the component. If there is interference, the path planning is readjusted;

[0043] 2-3-2) Determine the length:

[0044] a. Length of the motion harness in its shortest state:

[0045] After determining the shortest laying path, the length of the moving harness in the shortest state is obtained through the built-in harness design module of CATIA;

[0046] b. Harness motion path length increment: Harness length required for the motion path from the shortest state to the longest state when the harness follows the mobile interface:

[0047] Algorithms based on geometric path calculation:

[0048] Decompose the motion path into multiple basic geometric elements; for a straight line segment, use the distance formula between two points (x1, y1, z1) and (x2, y2, z2) to calculate its length, that is:

[0049]

[0050] Add up the lengths of all straight line segments;

[0051] For arc segments, the arc length is calculated based on the arc radius R and the center angle θ using the arc length formula, namely:

[0052] L=R*θ

[0053] Add up the arc lengths of all arc segments, and finally add the sum of the straight line segment lengths to the sum of the arc segment lengths to obtain the maximum length of the entire harness motion path;

[0054] Total length of harness = (length of harness in initial state + increment of harness moving path length) * relaxation coefficient;

[0055] Among them, the relaxation coefficient is comprehensively determined based on the vibration environment, transmission voltage and bending performance of the wire harness.

[0056] The step 3) comprises the following steps:

[0057] 3-1) Disassemble the wiring harness into each moving component:

[0058] According to the division of the motion mechanism transmission unit, the connectors and harness segments of the harness are divided into the component models to which they are fixed from the association matrix;

[0059] 3-2) Define the properties of each harness segment, including: define the properties of each harness segment diameter, minimum allowable bending radius, and length.

[0060] The step 4) comprises the following steps:

[0061] 4-1) Wire harness whole process simulation:

[0062] Enter the computer simulation software, set the motion step length, run the simulation, and update the harness model;

[0063] 4-2) Interference / bending / stretching compliance analysis:

[0064] Observe the various time forms of the moving harness segment, select the most extreme state segment, measure the parameters of the moving harness in each state segment, determine whether the minimum allowable bending radius requirements are met, whether there is stress accumulation, and whether the reserved displacement length is sufficient, observe whether the harness interferes with other structures, and redesign the harness solution if the above conditions are not met.

[0065] In step 4-1), the simulation is run to update the wiring harness model, specifically:

[0066] 4-1-1) Input the set motion step length, the motion law of the defined drive pair, and the initial state of the motion mechanism into the motion simulation module of CATIA; according to the principles of kinematics and dynamics, use the numerical integration algorithm to solve the state changes of the motion mechanism and the harness at each time step;.

[0067] 4-1-2) At each time step, calculate the position and posture changes of each component of the motion mechanism, and calculate the deformation and displacement of the harness according to the connection relationship between the harness and the components of the motion mechanism and the mechanical properties of the harness itself, until the entire set motion cycle is completed or the preset end condition is reached;

[0068] 4-1-3) Update harness model algorithm: After each time step simulation calculation is completed, obtain the new state information of the harness at this time, including the coordinate position of each node, the shape of the harness segment, and the mechanical parameter data; update the parameter data to the corresponding attribute field or data structure in the harness model to achieve real-time update of the harness model for subsequent analysis.

[0069] The step 4-2) is specifically:

[0070] 4-2-1) Determine the relevant indicators for judging the limit state, including: the bending angle of the wire harness, the stretching rate of the wire harness, and the distance between the wire harness and the surrounding components. For the wire harness state at each time step, obtain the value of the relevant indicator;

[0071] 4-2-2) Set the threshold range and filter the limit state segment;

[0072] 4-2-3) Accurately measure relevant parameters for each selected limit state segment;

[0073] For the bending radius, the curvature radius of the harness at the bending part is calculated, and the actual bending radius value is determined by using the curve fitting method, and then compared with the pre-set minimum allowable bending radius of the harness segment;

[0074] For stress conditions, the wire harness model is discretized into multiple units using the finite element analysis method. The stress value of each unit is calculated based on the mechanical equilibrium equation and the constitutive relationship of the material to check whether there is a stress concentration area, that is, by judging whether the stress value exceeds the yield strength of the material or the set safety stress threshold;

[0075] For the reserved displacement length, compare the maximum displacement of the harness during the actual movement with the displacement length reserved in the design to determine whether the reserved length is sufficient;

[0076] For interference, the spatial distance between the wiring harness and surrounding components is calculated to determine whether it is less than the interference threshold. If so, interference is determined to exist.

[0077] 4-2-4) If the actual bending radius of the wiring harness in each limit state segment is greater than or equal to the minimum allowable bending radius, there is no stress concentration area, the reserved displacement length is sufficient and there is no interference with other structures, then the wiring harness is judged to meet the requirements; otherwise, as long as one of the above conditions is not met, the wiring harness is judged to not meet the requirements and return to step 2) to redesign the wiring harness solution.

[0078] The present invention has the following beneficial effects and advantages:

[0079] 1. The present invention is suitable for more complex movements and can more intuitively output analysis results such as the length, shape, curvature, stretching and stress concentration points of the harness during the movement. In the early stages of design, the technical solution can be more accurately defined and the technical compliance analyzed, which has a certain positive significance in improving product reliability, shortening development time, and reducing product testing, material and labor costs in the functional verification stage.

[0080] 2. The present invention utilizes computer engineering software (CATIA) to achieve full motion process simulation of the wiring harness.

[0081] 3. The present invention can intuitively display any moment of the wire harness during its movement, observe the movement changes of the wire harness frame by frame, and verify whether the length, bending, stretching and stress concentration points of the wire harness meet the technical requirements.

[0082] 4. The present invention can ultimately output a photo of the wire harness at any moment during its movement, and can output a video of the movement changes of the wire harness during its entire movement process. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] Figure 1 A method flow chart of the overall implementation steps of the present invention;

[0084] Figure 2 A schematic diagram of the principle of defining a moving component according to an embodiment of the present invention;

[0085] Figure 3 A schematic diagram of the principle of the wiring harness solution defined in an embodiment of the present invention;

[0086] Figure 4 It is a schematic diagram of the principle of constructing a harness simulation model in the initial motion state of an embodiment of the present invention;

[0087] Figure 5 The figure is a schematic diagram of the principle of wire harness simulation and compliance analysis according to an embodiment of the present invention. DETAILED DESCRIPTION

[0088] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present disclosure and to be able to fully convey the scope of the present disclosure to those skilled in the art. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features described in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0089] like Figure 1As shown in FIG. 1 , it is a method flow chart of the overall implementation steps of the present invention. The present invention is a method for simulating the whole process motion of a wiring harness based on CATIA, which is characterized by comprising the following steps:

[0090] 1) Construct a motion mechanism simulation model;

[0091] 2) Define the main properties that affect the motion of the cable harness, including cable composition, diameter, length, stiffness, and minimum allowable bend radius;

[0092] 3) Establish a harness simulation model based on the motion mechanism simulation model and the defined main properties;

[0093] 4) Based on the harness simulation model, simulate the harness on the motion mechanism and update the harness simulation model in real time. At the same time, select the most extreme state segment in each time form of the motion harness segment for compliance analysis;

[0094] 5) If the conformity analysis is passed, the images of each moment of the harness simulation model are output, and the screenshots under a fixed viewing angle are regenerated into a video through video synthesis software. If the conformity analysis is not passed, return to step 2).

[0095] In the above steps, a person skilled in the art can understand the specific meanings of the following terms in the present invention according to specific circumstances.

[0096] 1. Motion components: The transmission units that constitute the motion mechanism, such as the three connecting rods of the three-bar linkage, gears, racks, etc., which are unit components that can perform a certain motion. Motion components can be composed of multiple parts.

[0097] 2.EWIS: The abbreviation of Electrical Wiring Interconnection System, which is the upper system-level product of the wiring harness.

[0098] 3. Wire harness stiffness: The wire harness is not a purely flexible body, it has a certain degree of stiffness, which is specifically reflected in the mechanical properties of whether the wire harness is easy to bend. The bending performance of the wire harness is an inherent characteristic, which is affected by the materials and process methods such as the wires, wrappings, and binding spacing that constitute the wire harness.

[0099] 4. Minimum bending radius of the wire harness: The minimum allowable bending radius of the wire harness is a quantitative parameter that reflects the stiffness of the wire harness. When the actual bending radius of the wire harness is greater than the minimum allowable bending radius, the performance of the wire harness can be considered intact, otherwise it is damaged.

[0100] 5. Transmission pair: A transmission pair is a mechanical component that transmits power and has one degree of freedom of movement. It consists of two or more components, one of which is the active component and the other is the driven component. The active component drives the movement of the driven component through its movement, thereby achieving power transmission. Common transmission pairs include gear pairs, worm gear pairs, thread pairs, sliding pairs, etc.

[0101] 6. Driving pair: The transmission pair that provides the original kinetic energy is called the driving pair.

[0102] Specifically, the present invention further describes the detailed implementation steps based on the embodiments, which are as follows:

[0103] like Figure 2 As shown, the embodiment has 11 transmission pairs and 10 moving components.

[0104] 1. Construction of motion mechanism simulation model

[0105] 1-1) Define and divide the moving components: Analyze the transmission principle of the moving mechanism, define each transmission unit (for the transmission mechanism not related to the harness movement, it can be simplified), and divide the various parts that make up the moving mechanism into the corresponding transmission units.

[0106] Specifically, the steps to define and divide the motion components are as follows:

[0107] Determine the energy transfer path and motion conversion mode of each transmission unit in the motion mechanism, and identify each link from power input to the final execution of the action;

[0108] The motion mechanism is abstracted into nodes, i.e., individual parts; the edges represent the connection and motion transmission relationship between the parts; the network structure is composed through topological analysis, and different transmission units are determined by traversing and analyzing the network;

[0109] The parts are divided according to their direct association and functional coordination in the transmission process, and an association matrix is ​​established. The rows of the matrix correspond to the parts, and the columns correspond to the transmission units that have been preliminarily determined. By analyzing the assembly relationship and motion transmission matching conditions between the parts, if the part participates in the motion transmission of a certain transmission unit, the corresponding matrix element position is marked as 1, otherwise it is marked as 0. Finally, the accurate division of parts to transmission units is completed based on the association matrix.

[0110] 1-2) Sub-assembly of each moving component: According to the division results of the moving components, the parts contained in each moving component are clarified and assembled into sub-assembly.

[0111] 1-3) General assembly of the motion mechanism: Assemble all the moving components into a motion mechanism, and define the transmission and constraints between the moving components.

[0112] 1-4) Motion simulation:

[0113] (1) Define the fixed component and the driving pair as follows Figure 2 As shown in the example:

[0114] The fixed component is "8-mechanism component (i.e. fixed bearing)", the driving pair is "Ⅰ-transmission pair", and the driving measurement is "rotation angle".

[0115] Components that remain unchanged relative to the earth or reference coordinate system during the entire motion process are marked as fixed components by analyzing the supporting structure and working status of the mechanism, and their positions and postures are set to be fixed in the model;

[0116] Combined with the power input of the mechanism, determine the kinematic pair that provides active motion; according to the motion characteristics of the power source, including: the speed and torque curve of the motor, the stroke and thrust curve of the cylinder, set the motion parameters of the driving pair, and use a function expression to describe the change of the motion of the driving pair over time;

[0117] (2) After the definition is completed, the degrees of freedom of the motion mechanism are calculated. When the degrees of freedom = 0, the mechanism can be simulated. The algorithm for calculating the degrees of freedom of the motion mechanism is:

[0118] Based on the degree of freedom calculation, for a planar mechanism, the degrees of freedom are:

[0119] F=3n-2P L -P H

[0120] Where n is the number of active components, P L For low pair number, P H It is the high vice number;

[0121] For spatial mechanisms, the degrees of freedom are calculated according to the corresponding extended degree of freedom calculation formula.

[0122] 2. Definition of wiring harness scheme

[0123] The main properties that affect the motion of the cable harness, namely cable composition, diameter, length, stiffness and minimum allowable bending radius, are defined in Figure 3 Example - Harness scheme definition.

[0124] 2-1) Define the cable model of the integrated harness. Determine the cable types inside the harness, such as single wire, twisted wire, shielded wire, coaxial wire, and Ethernet, and determine the specifications and quantity of each wire;

[0125] 2-2) Determine the outer diameter of the harness based on an empirical formula or effective calculation methods such as the definition formula in HB7756.14 (based on CATIA modeling requirements Part 14: Harness routing);

[0126] 2-3) Define the rigidity of the wire harness / determine the minimum allowable bending radius of the wire harness. Determine the minimum allowable bending radius of the wire harness based on effective calculation methods such as empirical formulas or the definition formula in SAE AS50881 (Wiring Aerospace Vehicle).

[0127] 2-4) Define the laying path and determine the length. For wire harness products installed on moving mechanisms, the wire harness segments are generally divided into two forms: "fixed segment" and "moving segment" for separate design and analysis. Since the moving segment wire harness moves with the movement of the mechanism, if the reserved displacement length of the wire harness is too long, it will affect or even damage the performance of the wire harness and reduce the reliability of the wire harness product. Therefore, the wire harness needs to be designed with a suitable displacement length. For the wire harness segment (fixed segment) that is relatively stationary with the movement of the mechanism, it is sufficient to meet the general wire harness related requirements.

[0128] The steps for defining the laying path and determining the length in this embodiment are as follows:

[0129] 2-4-1) Based on the connector interface corresponding to the motion mechanism simulation model, determine its coordinate position in the model space; according to the layout of the components, use the path planning algorithm to determine the laying path of the wire harness; abstract the motion mechanism simulation model into a graph structure, with nodes representing key component positions and connector interfaces, and edges representing feasible laying channels. With the starting connector interface as the starting point and the target connector interface as the end point, search for the shortest laying path;

[0130] During the search process, the restrictions imposed by the geometric shape of the moving component on the path are considered, and the collision detection algorithm is used to determine whether the harness path interferes with the component. If there is interference, the path planning is readjusted;

[0131] 2-4-2) Determine the length:

[0132] a. Length of the motion harness in its shortest state:

[0133] After determining the shortest laying path, the length of the moving harness in the shortest state is obtained through the built-in harness design module of CATIA;

[0134] b. Harness motion path length increment: Harness length required for the motion path from the shortest state to the longest state when the harness follows the mobile interface:

[0135] Algorithms based on geometric path calculation:

[0136] Decompose the motion path into multiple basic geometric elements; for a straight line segment, use the distance formula between two points (x1, y1, z1) and (x2, y2, z2) to calculate its length, that is:

[0137]

[0138] Add up the lengths of all straight line segments;

[0139] For arc segments, the arc length is calculated based on the arc radius R and the center angle θ using the arc length formula, namely:

[0140] L=R*θ

[0141] Add up the arc lengths of all arc segments, and finally add the sum of the straight line segment lengths to the sum of the arc segment lengths to obtain the maximum length of the entire harness motion path;

[0142] Total length of harness = (length of harness in initial state + increment of harness moving path length) * relaxation coefficient;

[0143] Among them, the relaxation coefficient is comprehensively determined based on the vibration environment, transmission voltage and bending performance of the wire harness.

[0144] 3. Construction of wiring harness simulation model

[0145] 3-1) Disassemble the wiring harness to each moving component.

[0146] According to the division of the motion mechanism transmission unit, the connectors and harness segments of the harness are divided into the component models to which they are fixed. Figure 4 The illustrated embodiment - wiring harness simulation model building.

[0147] 3-2) Define the properties of each harness segment. Define the properties of each harness segment, such as diameter, minimum allowable bending radius, length, etc.

[0148] 4. Motion Harness Simulation and Compliance Analysis

[0149] 4-1) Wire harness whole process simulation:

[0150] Enter the computer simulation software. This embodiment uses the CATIA Kinematics (kinematic mechanism module) design module; set the motion step length. The drive step length of this embodiment is set to 1°; run the simulation and update the harness model;

[0151] The whole process simulation of the wiring harness includes the following steps:

[0152] 4-1-1) Input the set motion step length, the motion law of the defined drive pair, and the initial state of the motion mechanism into the motion simulation module of CATIA; according to the principles of kinematics and dynamics, use the numerical integration algorithm to solve the state changes of the motion mechanism and the harness at each time step;.

[0153] 4-1-2) At each time step, calculate the position and posture changes of each component of the motion mechanism, and calculate the deformation and displacement of the harness according to the connection relationship between the harness and the components of the motion mechanism and the mechanical properties of the harness itself, until the entire set motion cycle is completed or the preset end condition is reached;

[0154] 4-1-3) Update harness model algorithm: After each time step simulation calculation is completed, obtain the new state information of the harness at this time, including the coordinate position of each node, the shape of the harness segment, and the mechanical parameter data; update the parameter data to the corresponding attribute field or data structure in the harness model to achieve real-time update of the harness model for subsequent analysis.

[0155] 4-2) Interference / bending / stretching compliance analysis:

[0156] Observe the various states of the moving harness segment, select the most extreme state segment, measure the parameters of the moving harness in each state segment, determine whether it meets the minimum allowable bending radius requirements, whether there is stress accumulation, whether the reserved displacement length is sufficient, and observe whether the harness interferes with other structures. If the above conditions are not met, redesign the harness solution. Figure 5 Example - Harness motion simulation machine compliance analysis, specifically perform the following steps:

[0157] 4-2-1) Determine the relevant indicators for judging the limit state, including: the bending angle of the wire harness, the stretching rate of the wire harness, and the distance between the wire harness and the surrounding components. For the wire harness state at each time step, obtain the value of the relevant indicator;

[0158] 4-2-2) Set the threshold range and filter the limit state segment;

[0159] 4-2-3) Accurately measure relevant parameters for each selected limit state segment;

[0160] For the bending radius, the curvature radius of the harness at the bending part is calculated, and the actual bending radius value is determined by using the curve fitting method, and then compared with the pre-set minimum allowable bending radius of the harness segment;

[0161] For stress conditions, the wire harness model is discretized into multiple units using the finite element analysis method. The stress value of each unit is calculated based on the mechanical equilibrium equation and the constitutive relationship of the material to check whether there is a stress concentration area, that is, by judging whether the stress value exceeds the yield strength of the material or the set safety stress threshold;

[0162] For the reserved displacement length, compare the maximum displacement of the harness during the actual movement with the displacement length reserved in the design to determine whether the reserved length is sufficient;

[0163] For interference, the spatial distance between the wiring harness and surrounding components is calculated to determine whether it is less than the interference threshold. If so, interference is determined to exist.

[0164] 4-2-4) If the actual bending radius of the wiring harness in each limit state segment is greater than or equal to the minimum allowable bending radius, there is no stress concentration area, the reserved displacement length is sufficient and there is no interference with other structures, then the wiring harness is judged to meet the requirements; otherwise, as long as one of the above conditions is not met, the wiring harness is judged to not meet the requirements and return to step 2) to redesign the wiring harness solution.

[0165] 5. Result Output

[0166] 5-1) Pictures: In order to improve efficiency, use VBA program to output pictures, that is, use the program to adjust the driving parameters (rotation angle in the embodiment), update the wiring harness model, take screenshots, and save them to a specified folder.

[0167] 5-2) Video: Use video synthesis software to create videos from screenshots taken at a fixed perspective.

[0168] To sum up, in combination with the protection content of the present invention and the embodiments of the present invention, the present invention provides a relatively complete and rigorous wire harness motion simulation process based on CATIA, from motion mechanism modeling to wire harness attribute definition, simulation model establishment, simulation analysis to result output, which helps to accurately evaluate the actual performance of the wire harness on the motion mechanism and guide related design optimization.

[0169] Although preferred embodiments of the present invention have been described, additional changes and modifications may be made to these embodiments by those skilled in the art once the basic inventive concepts are known. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention. Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for full-process motion simulation of wiring harness based on CATIA, characterized in that: The following steps are involved: 1) Construct a motion mechanism simulation model; 2) Define the main properties that affect the motion of the cable harness, including cable composition, diameter, length, stiffness, and minimum allowable bend radius; 3) Establish a harness simulation model based on the motion mechanism simulation model and the defined main properties; 4) Based on the harness simulation model, simulate the harness on the motion mechanism and update the harness simulation model in real time. At the same time, select the most extreme state segment in each time form of the motion harness segment for compliance analysis; 5) If the conformity analysis is passed, the images of each moment of the harness simulation model are output, and the screenshots under a fixed viewing angle are regenerated into a video through video synthesis software. If the conformity analysis is not passed, return to step 2).

2. The method for CATIA-based full-process motion simulation of a wiring harness according to claim 1, characterized in that: The step 1) comprises the following steps: 1-1) Define and divide motion components: Analyze the transmission principle of the motion mechanism, define each transmission unit, and divide the parts that constitute the motion mechanism into corresponding transmission units; 1-2) Each moving component subassembly: According to the division results of the moving components, the parts contained in each moving component are identified and assembled into subassemblies; 1-3) General assembly of motion mechanism: Assemble all moving components into a moving mechanism, and define the transmission and constraints between the moving components; 1-4) Motion simulation: Define the fixed components and driving pairs; after the definition is completed, calculate the degrees of freedom of the motion mechanism, and when the degrees of freedom are 0, the mechanism performs simulation.

3. The method for CATIA-based full-process harness motion simulation according to claim 2, characterized in that: The step 1-1) is specifically: Determine the energy transfer path and motion conversion mode of each transmission unit in the motion mechanism, and identify each link from power input to the final execution of the action; The motion mechanism is abstracted into nodes, i.e., individual parts; edges represent the connection and motion transmission relationship between parts; Through topological analysis, the network structure is formed, and different transmission units are determined by traversing and analyzing the network; The parts are divided according to their direct association and functional coordination in the transmission process, and an association matrix is ​​established. The rows of the matrix correspond to the parts, and the columns correspond to the transmission units that have been preliminarily determined. By analyzing the assembly relationship and motion transmission matching conditions between the parts, if the part participates in the motion transmission of a certain transmission unit, the corresponding matrix element position is marked as 1, otherwise it is marked as 0. Finally, the accurate division of parts to transmission units is completed based on the association matrix.

4. The method for CATIA-based full-process harness motion simulation according to claim 2, characterized in that: The steps 1-4) are specifically: (1) Define the fixed component and the driving pair: Components that remain unchanged relative to the earth or reference coordinate system during the entire motion process are marked as fixed components by analyzing the supporting structure and working status of the mechanism, and their positions and postures are set to be fixed in the model; Combined with the power input of the mechanism, determine the kinematic pair that provides active motion; according to the motion characteristics of the power source, including: the speed and torque curve of the motor, the stroke and thrust curve of the cylinder, set the motion parameters of the driving pair, and use a function expression to describe the change of the motion of the driving pair over time; (2) Algorithm for calculating the degrees of freedom of the motion mechanism: Based on the degree of freedom calculation, for a planar mechanism, the degrees of freedom are: F=3n-2P L -P H Where n is the number of active components, P L For low pair number, P H It is the high pair number; For spatial mechanisms, the degrees of freedom are calculated according to the corresponding extended degree of freedom calculation formula.

5. The method for CATIA-based full-process motion simulation of a wiring harness according to claim 1, characterized in that: The step 2) comprises the following steps: 2-1) Define the cable model of the integrated harness: determine the cable types inside the harness, including single wire, twisted wire, shielded wire, coaxial and Ethernet; and determine the specifications and quantity of each wire; 2-2) Determine the outer diameter of the wire harness according to the empirical formula; then define the wire harness stiffness and determine the minimum allowable bending radius of the wire harness; 2-3) Define the laying path and determine the length.

6. The method for CATIA-based full-process harness motion simulation according to claim 5, characterized in that: The steps 2-3) are specifically: 2-3-1) Based on the connector interface corresponding to the motion mechanism simulation model, determine its coordinate position in the model space; according to the layout of the components, use the path planning algorithm to determine the laying path of the wire harness; abstract the motion mechanism simulation model into a graph structure, with nodes representing key component positions and connector interfaces, and edges representing feasible laying channels. With the starting connector interface as the starting point and the target connector interface as the end point, search for the shortest laying path; During the search process, the restrictions imposed by the geometric shape of the moving component on the path are considered, and the collision detection algorithm is used to determine whether the harness path interferes with the component. If there is interference, the path planning is readjusted; 2-3-2) Determine the length: a. Length of the motion harness in its shortest state: After determining the shortest laying path, the length of the moving harness in the shortest state is obtained through the built-in harness design module of CATIA; b. Harness motion path length increment: Harness length required for the motion path from the shortest state to the longest state when the harness follows the mobile interface: Algorithm based on geometric path calculation: Decompose the motion path into multiple basic geometric elements; for a straight line segment, use the distance formula between two points (x1, y1, z1) and (x2, y2, z2) to calculate its length, that is: Add up the lengths of all straight line segments; For arc segments, the arc length is calculated based on the arc radius R and the center angle θ using the arc length formula, namely: L=R*θ Add up the arc lengths of all arc segments, and finally add the sum of the straight line segment lengths to the sum of the arc segment lengths to obtain the maximum length of the entire harness motion path; Total length of harness = (length of harness in initial state + increment of harness moving path length) * relaxation coefficient; Among them, the relaxation coefficient is comprehensively determined based on the vibration environment, transmission voltage and bending performance of the wire harness.

7. The method for full-process motion simulation of a wiring harness based on CATIA according to claim 1, characterized in that: The step 3) comprises the following steps: 3-1) Disassemble the wiring harness into each moving component: According to the division of the motion mechanism transmission unit, the connectors and harness segments of the harness are divided into the component models to which they are fixed from the association matrix; 3-2) Define the properties of each harness segment, including: define the properties of each harness segment diameter, minimum allowable bending radius, and length.

8. The method for CATIA-based full-process harness motion simulation according to claim 1, characterized in that: The step 4) comprises the following steps: 4-1) Wire harness whole process simulation: Enter the computer simulation software, set the motion step length, run the simulation, and update the harness model; 4-2) Interference / bending / stretching compliance analysis: Observe the various time forms of the moving harness segment, select the most extreme state segment, measure the parameters of the moving harness in each state segment, determine whether the minimum allowable bending radius requirements are met, whether there is stress accumulation, and whether the reserved displacement length is sufficient, observe whether the harness interferes with other structures, and redesign the harness solution if the above conditions are not met.

9. The method for CATIA-based full-process motion simulation of a wiring harness according to claim 8, characterized in that: In step 4-1), the simulation is run to update the wiring harness model, specifically: 4-1-1) Input the set motion step length, the motion law of the defined drive pair, and the initial state of the motion mechanism into the motion simulation module of CATIA; according to the principles of kinematics and dynamics, use the numerical integration algorithm to solve the state changes of the motion mechanism and the harness at each time step;. 4-1-2) At each time step, calculate the position and posture changes of each component of the motion mechanism, and calculate the deformation and displacement of the harness according to the connection relationship between the harness and the components of the motion mechanism and the mechanical properties of the harness itself, until the entire set motion cycle is completed or the preset end condition is reached; 4-1-3) Update the harness model algorithm: After each time step simulation calculation is completed, obtain the new state information of the harness at this time, including the coordinate position of each node, the shape of the harness segment, and the mechanical parameter data; Update the parameter data to the corresponding attribute fields or data structures in the harness model to achieve real-time update of the harness model for subsequent analysis.

10. The method for CATIA-based full-process harness motion simulation according to claim 8, characterized in that: The step 4-2) is specifically: 4-2-1) Determine the relevant indicators for judging the limit state, including: the bending angle of the wire harness, the stretching rate of the wire harness, and the distance between the wire harness and the surrounding components. For the wire harness state at each time step, obtain the value of the relevant indicator; 4-2-2) Set the threshold range and filter the limit state segment; 4-2-3) Accurately measure relevant parameters for each selected limit state segment; For the bending radius, the curvature radius of the harness at the bending part is calculated, and the actual bending radius value is determined by using the curve fitting method, and then compared with the pre-set minimum allowable bending radius of the harness segment; For stress conditions, the wire harness model is discretized into multiple units using the finite element analysis method. The stress value of each unit is calculated based on the mechanical equilibrium equation and the constitutive relationship of the material to check whether there is a stress concentration area, that is, by judging whether the stress value exceeds the yield strength of the material or the set safety stress threshold; For the reserved displacement length, compare the maximum displacement of the harness during the actual movement with the displacement length reserved in the design to determine whether the reserved length is sufficient; For interference, the spatial distance between the wiring harness and surrounding components is calculated to determine whether it is less than the interference threshold. If so, interference is determined to exist. 4-2-4) If the actual bending radius of the wiring harness in each limit state segment is greater than or equal to the minimum allowable bending radius, there is no stress concentration area, the reserved displacement length is sufficient and there is no interference with other structures, then the wiring harness is judged to meet the requirements; otherwise, as long as one of the above conditions is not met, the wiring harness is judged to not meet the requirements and return to step 2) to redesign the wiring harness solution.

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