A method for automatic laying of cables in a three-dimensional environment

Abstract

The application provides a kind of automatic cable laying method under three-dimensional environment, comprising: constructing three-dimensional model, inputting the physical attribute information of cable, electrical schematic diagram and wiring specification;According to the wiring constraint, based on the feature voxelization extraction technology, extract voxel model;According to voxel model, through definition grid node division solving space;Combining optimization A* algorithm, solve initial collision-free path under cable wiring environment;Combining cable wiring standard, screen initial path node, and complete wall attachment processing;Establish cable statics equation, solve cable form under equilibrium state, based on spline curve fitting to obtain the final form of cable, output cable form, key node information table and cable information report form.The application can complete the fast solution of cable laying form under three-dimensional environment, and complete the acquisition of wiring key point information according to the wiring standard, improve the precision and efficiency of automatic cable layout, which is beneficial to the digitization and lightweight design of electromechanical products.

Description

Technical Field

[0001] This invention relates to the field of computer-aided cable layout design technology, and more particularly to an automatic cable laying method in a three-dimensional environment. Background Technology

[0002] As the connection and control unit of electrical equipment, electrical components, and system control devices, cables primarily serve to transmit signals. The quality of cable layout significantly impacts the performance of complex electromechanical products. However, the wide variety of cable types, complex shapes, and limited assembly space make it easy for improper layout, incorrect installation, omissions, and insufficient reliability to occur during actual layout design. This affects the product lifespan of cables, and consequently leads to centroid shifts, excessive weight, and other quality problems in complex electromechanical products.

[0003] Traditional cable layout design is a two-dimensional, serial method based on manual wiring. It relies heavily on manual operation, resulting in low efficiency, high cost, and an inability to predict problems encountered during actual installation and use. Unlike computers, it often cannot consider key cable parameters (such as minimum bending radius) during the layout process. Computer-aided cable layout design is an effective way to solve these problems. However, current computer-aided cable layout design software typically uses interactive wiring methods, does not consider the flexible deformation characteristics of cables, lacks obstacle avoidance capabilities, and cannot guarantee assembly rationality. The development of virtual cable layout systems based on virtual reality technology has become a new direction in cable wiring design research.

[0004] Based on virtual reality technology, and guided by wiring schematics, cable routing is performed virtually according to the electrical and interference constraints of the digital model prototype, ultimately generating a feasible routing plan. Throughout the process, the cable design and layout are completely consistent with the physical product trial assembly, thus avoiding changes to the design concept during physical prototype testing and providing training on the cable assembly process. Early applications of virtual reality technology in cable layout design involved interactive layout methods. In a virtual environment, using human-computer interaction devices, the optimal cable layout path without constraints or collisions was obtained based on engineering knowledge or experience. However, when the number of cables is large and the layout environment is complex, this method is difficult to use quickly and effectively to complete the layout design task. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides an automated cable laying method in a three-dimensional environment. Guided by path planning and nonlinear optimization mechanisms, it fully utilizes automatic path search strategies, finite element discretization principles, the physical model of flexible cables, and the principle of minimum potential energy to form a highly operable and accurate automated cable laying mechanism for complex electromechanical products.

[0006] The technical means employed in this invention are as follows:

[0007] An automated cable laying method in a three-dimensional environment includes:

[0008] S1. Construct a 3D model, inputting the physical properties of the cable, electrical schematic diagram, and wiring specifications;

[0009] S2. Based on the wiring constraints, extract the voxel model using the feature voxelization extraction technique; based on the voxel model, divide the solution space by defining grid nodes;

[0010] S3. Combine the optimized A* algorithm to solve the initial collision-free path in the cable cabling environment; combine the cable cabling standards to filter the nodes of the initial path and complete the wall-hugging process.

[0011] S4. Establish the cable static equation, solve for the cable shape under equilibrium state, obtain the final shape of the cable based on spline curve fitting, and output the automatic cable laying results.

[0012] Further, in step S2, based on feature voxelization extraction technology, a voxel model is extracted, specifically including:

[0013] S21. Define the maximum and minimum dimensions x of the model. min x max y min y max z min z max The model's AABB bounding box; the bounding box is divided into a set of multiple spatial cubes, with the number of cubes being L′×H′×W′;

[0014] S22, with R 3 A voxel is defined as a region centered at coordinates (x, y, z) and containing a continuous space (u, v, w), where x - 0.5 < u ≤ x + 0.5, y - 0.5 < v ≤ y + 0.5, and z - 0.5 < w ≤ z + 0.5.

[0015] S23. Using the ray casting method, project the triangular facet onto the X and Y planes from the Z direction. The coordinates of the points falling inside the triangle satisfy x min ≤x≤x max And y min ≤y≤y max ;

[0016] S24. Traverse all points in step S23, determine the plane where the triangular facet is located, and record the coordinates of the spatial points on the plane;

[0017] S25. Repeat the above process to calculate the coordinates of voxel points on the surface of all triangular facets. Based on the detection results of the ray scan, determine whether it is a closed model. Apply the scan line seed filling algorithm to calculate the internal voxels and complete the model voxelization.

[0018] Further, in step S2, the solution space is divided by defining grid nodes according to the voxel model, specifically including:

[0019] S26. Establish a coordinate system centered on the voxelized model coordinate system. Let the diameter of the cable be D, and select the grid granularity λ = D.

[0020] S27. Determine the three-dimensional dimensions of the wiring space L×H×W, and convert the wiring space into a discrete space of L′×H′×W′, where L′=L / λ, H′=H / λ, W′=W / λ, and L′, H′, W′ are the results of rounding up;

[0021] S28. Assign values ​​to grid nodes according to their attributes, where nodes with a weight of 1 are considered obstacle nodes, and nodes with a weight of 0 are considered feasible nodes.

[0022] S29. Based on the "part is all" strategy, complete the grid-based division of the wiring space.

[0023] Furthermore, in step S3, the initial collision-free path in the cable routing environment is solved by combining the optimized A* algorithm, specifically including:

[0024] S31. Add the starting point to Open_List to complete the initialization of Open_List and Close_List;

[0025] S32. Determine if Open_List is empty. If it is not empty, select the node n with the smallest f value; otherwise, the path search fails.

[0026] S33. Determine if node n is the endpoint. If it is not the endpoint, continue to the next step. If it is the endpoint, complete the search.

[0027] S34. Remove node n from Open_List and add it to Close_List; filter the child nodes around node n. If the child node is not in Open_List, add it to Open_List and calculate the value of f; if it is in Open_List, perform the step of updating the value of g; if the child node is determined to be an obstacle, ignore the child node.

[0028] S35. Repeat the above process until the destination is found; when the destination is found, backtrack the path node set, and the path node set with the minimum overall cost is the optimal path.

[0029] Furthermore, in step S3, the initial path nodes are screened in accordance with cable wiring standards, and wall-mounting processing is completed, specifically including:

[0030] S36. Set a reference plane for the wall, and set the attraction area within the scope of the reference plane;

[0031] S37. Determine whether the node is the start or end point. If it is, ignore the node; otherwise, proceed to step S38.

[0032] S38. Determine whether the node is within the attraction zone. If it is within the attraction zone, move the node to the reference plane surface and replace the original path node with the moved node.

[0033] S39. Repeat the above steps until all path nodes are attracted to the reference plane.

[0034] Further, step S4 specifically includes:

[0035] S41. Based on Cosserat's elastic rod theory, establish a static model of the cable;

[0036] S42. Solve the static equilibrium state of the cable based on the principle of minimum potential energy and optimization theory;

[0037] S43. Based on the idea of ​​cubic spline curve fitting, generate the shape of the cable centerline.

[0038] Further, step S41 specifically includes:

[0039] S411. According to the theory of elastic rods, the cable is regarded as a slender rod with its axial dimension much larger than its radial dimension; the cable centerline is a smooth curve of second order or higher, passing through the center of the cross section; the cable has no shear deformation, and its cross section remains unchanged before and after deformation, always being a rigid cross section; the cable tensile deformation and initial deformation are ignored; the influence of each layer of the cable is not considered, and it is regarded as an isotropic elastic rod.

[0040] S412. Based on the theory of elastic rods, the spatial shape of a cable consists of the position of its centerline and the shape of its cross-sections. The position of the cable's centerline is represented by the vector r(s). The positional relationship between cross-sections p' and p includes movement along the centerline and rotation between the cross-sections. When the movement distance s is small enough, the relationship between the two cross-sections can be regarded as rotation about a fixed point, represented by the direction cosine matrix.

[0041] S413. The attitude of the cross section is represented by Euler parameters, and the direction cosine matrix is ​​expressed by Euler parameters as follows:

[0042]

[0043]

[0044] S414. Based on the finite element method, the cable is divided into n nodes, and adjacent nodes are connected to form an element. Using Euler parameters for linear interpolation within the element, the position and direction cosine matrices of the discretized i-th node are obtained, as shown below:

[0045]

[0046]

[0047] Further, step S42 specifically includes:

[0048] S421. Establish the potential energy equation for the cable. Including gravitational potential energy Bending potential energy E bending,i =0.5K b κ i 2 Reversing potential energy

[0049] S422. Using the discrete point potential energy equation of the cable as the objective function, Euler parameters as variables, and the boundary condition locations and Euler parameters as constraints, establish an optimization model for the cable model, as shown in the following expression:

[0050]

[0051] S423. Select initial point x (0) Set the termination condition ε and the number of iterations k;

[0052] S424, Construction point x (k) Depart, select search direction d (k) This reduces the objective function f(x);

[0053] S425, from x (k) Departure from d (k) Find the appropriate amount of movement α in the direction (k) To obtain a satisfactory descent in that direction, α (k) Called point x (k) Along the search direction d (k) Step size;

[0054] S426, Let x (k+1) =x (k) +α (k) d (k) If |f(x) (k+1) )-f(x (k) If | > ε, then the iteration count increases by 1, and execution continues from step S422; if at iteration point x * At, |f(x) (k+1) )-f(x(k) If | < ε, the algorithm stops and outputs the minimum point x. * , formula |f(x (k+1) )-f(x (k) The condition )|<ε is called the termination condition.

[0055] Further, step S43 specifically includes:

[0056] S431. Data points are the spatial points that must be passed through during cable routing. Based on adjacent data points P1 and P2, construct a parametric cubic spline curve between the two points. When constructing the curve equation, the vector form of the equation is adopted.

[0057] S432. Given n data points in space, piecewise fitting is performed based on adjacent data points to sequentially construct cubic spline curves between adjacent points. A total of n-1 curves can be constructed, determined by P. i P i+1 The cubic polynomial parametric vector equation of the i-th curve segment formed by two points can be expressed as:

[0058]

[0059] S433. Solve for the tangent vector, utilizing the connection between two adjacent curve segments having C. 2 Level smoothness, i.e., P i " - =P i " + , P″ i-1 (t=t i-1 ) = P i "(t=0), we get the equation:

[0060]

[0061] S434. The established tangent vector equation system is a linear equation system, and the coefficient matrix of the equation system is a tridiagonal matrix. The linear equation system is solved using the chasing method. The chasing method first performs LU decomposition on the coefficient matrix, decomposing the coefficient matrix into the product of the lower triangular matrix L and the upper triangular matrix U. Finally, the equation system is solved by two back substitutions.

[0062] Compared with the prior art, the present invention has the following advantages:

[0063] 1. The automatic cable laying method in a three-dimensional environment provided by the present invention takes into account the accurate acquisition of the cable laying environment, completes the accurate acquisition of the three-dimensional cable wiring environment features based on voxelization feature extraction technology, and completes the wiring space preprocessing based on the grid space method, including space division and space node definition.

[0064] 2. The automatic cable laying method in a three-dimensional environment provided by the present invention is aimed at the requirements of automatic cable laying. Based on the improved A* algorithm, it considers the requirements of cable layout without collision, wall-hugging, flexibility and economic constraints, and calculates the initial path of the cable in a three-dimensional environment.

[0065] 3. The automatic cable laying method in a three-dimensional environment provided by this invention considers the influence of cable physical parameters, completes the physical modeling of the cable based on the Cosserat elastic rod theory, and solves the static equilibrium shape of the cable based on the principle of minimum potential energy and the finite element method. The initial path of the cable is optimized based on cubic spline curve fitting.

[0066] In summary, compared with traditional computer-aided cable layout design modules, the automatic cable optimization laying method based on physical modeling proposed in this invention takes into account the cable routing constraints, physical constraints, and economic constraints. It can effectively reduce the design length of cables, improve cable routing efficiency, and has strong guiding significance for actual cable routing.

[0067] Based on the above reasons, this invention can be widely applied in fields such as computer-aided cable laying. Attached Figure Description

[0068] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0069] Figure 1 This is a flowchart illustrating the automatic cable laying process of the present invention.

[0070] Figure 2 This is a schematic diagram of spatial feature extraction and preprocessing according to the present invention.

[0071] Figure 3 This is a flowchart of the A* algorithm execution of the present invention.

[0072] Figure 4 This is a flowchart of the wall-attachment constraint process of the present invention.

[0073] Figure 5 This is a flowchart illustrating the modeling and calculation process of this invention.

[0074] Figure 6 This is a schematic diagram of the wiring result of the present invention. Detailed Implementation

[0075] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0076] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0077] like Figure 1 As shown, this invention provides an automatic cable laying method in a three-dimensional environment. This method first requires inputting a cable laying information report, extracting features from a digital prototype, and completing grid division, such as... Figure 2 As shown, the initial cable path is generated using the improved A* algorithm, and the path point nodes are selected and the wall-hugging constraints are processed according to the wall-hugging constraint rules. Using the final path points as input, the static equilibrium positions of discrete points are solved based on the elastic rod model, and the final physical shape of the cable is generated based on spline curve fitting, thus completing the automatic cable laying.

[0078] In specific implementation, as a preferred embodiment of the present invention, such as Figure 3 As shown, this invention generates the initial path of a cable using an improved A* algorithm. The improvements include optimizing the heuristic function by considering the cable's flexibility and expanding the search direction by considering economic constraints. Based on the obtained digital prototype grid model, a collision-free initial path between the start and end points is calculated. Using the generated initial path as input, this invention, according to wiring standards, sets an attraction zone to attract path points within the attraction zone to the obstacle surface, completing the wall-attaching constraint processing, such as... Figure 4 As shown. Node selection was performed on the path points according to the wiring standards, with key point spacing ranging from 300mm to 600mm.

[0079] In specific implementation, as a preferred embodiment of the present invention, such as Figure 5As shown, this invention establishes a static model of the cable, using Cosserat's elastic rod theory to express the cable's deformation under bending, torsion, and gravity. Based on the principle of minimum potential energy, the potential energy equation of the cable is derived. Using the total potential energy as the objective function and Euler parameters as variables, an optimization equation is established to solve for the Euler parameters that minimize the cable's potential energy, thereby fitting the coordinates of discrete points. The final shape of the cable is generated based on cubic spline curve fitting technology. Figure 6 The image shows the result of laying internal cables for a certain aerospace product using a design example based on the present invention.

[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for automatic cable laying in a three-dimensional environment, characterized in that, include: S1. Construct a 3D model, inputting the physical properties of the cable, electrical schematic diagram, and wiring specifications; S2. Based on the wiring constraints, extract the voxel model using the feature voxelization extraction technique; based on the voxel model, divide the solution space by defining grid nodes; S3, Combining optimization A Algorithm for finding initial collision-free paths in a cable routing environment; In step S3, the initial path nodes are selected based on cable routing standards, and wall-mounting processing is completed. This specifically includes: S36. Set a reference plane for the wall to adhere to, and set the attraction area within the scope of the reference plane; S37. Determine whether the node is the start or end point. If it is, ignore the node; otherwise, proceed to step S38. S38. Determine whether the node is within the attraction zone. If it is within the attraction zone, move the node to the reference plane surface and replace the original path node with the moved node. S39. Repeat the above steps until all path nodes are attracted to the reference plane; S4. Establish the cable static equation, solve for the cable shape under equilibrium conditions, obtain the final cable shape based on spline curve fitting, and output the automatic cable laying results, specifically including: S41. Based on Cosserat's elastic rod theory, establish a static model of the cable; S42. Solve the static equilibrium state of the cable based on the principle of minimum potential energy and optimization theory; S43. Based on the idea of ​​cubic spline curve fitting, generate the shape of the cable centerline.

2. The automatic cable laying method in a three-dimensional environment according to claim 1, characterized in that, In step S2, a voxel model is extracted based on the feature voxelization extraction technique, specifically including: S21. Define the maximum and minimum dimensions of the model. , , , , , The model's AABB bounding box; dividing the bounding box into a set of multiple spatial cubes, the number of which is... ; S22, with coordinates in space Centered on, containing continuous space The region is defined as a voxel, where , , ; S23. Using the ray casting method, project the triangular facet onto the X and Y planes from the Z direction. The coordinates of the points falling inside the triangle satisfy... and ; S24. Traverse all points in step S23, determine the plane where the triangular facet is located, and record the coordinates of the spatial points on the plane; S25. Repeat the above process to calculate the coordinates of voxel points on the surface of all triangular facets. Based on the detection results of the ray scan, determine whether it is a closed model. Apply the scan line seed filling algorithm to calculate the internal voxels and complete the model voxelization.

3. The automatic cable laying method in a three-dimensional environment according to claim 1, characterized in that, In step S2, the solution space is divided by defining grid nodes based on the voxel model, specifically including: S26. Establish a coordinate system centered on the voxelized model coordinate system. Let the diameter of the cable be... Select grid granularity ; S27. Determine the three-dimensional dimensions of the wiring space. Convert wiring space into The discrete space, where , , ,and , , This is the result of rounding up. S28. Assign values ​​to grid nodes according to their attributes, where nodes with a weight of 1 are considered obstacle nodes, and nodes with a weight of 0 are considered feasible nodes. S29. Based on the "part is all" strategy, complete the grid-based division of the wiring space.

4. The automatic cable laying method in a three-dimensional environment according to claim 1, characterized in that, In step S3, combined with optimization A The algorithm solves for the initial collision-free path in a cable routing environment, specifically including: S31. Add the starting point to Open_List to complete the initialization of Open_List and Close_List; S32. Check if Open_List is empty. If it is not empty, select one of the items in it. The node n with the smallest value; otherwise, the path search fails. S33. Determine if node n is the endpoint. If it is not the endpoint, continue to the next step. If it is the endpoint, complete the search. S34. Remove node n from Open_List and add it to Close_List; filter the child nodes surrounding node n, and if the child node is not in Open_List, add it to Open_List and calculate... f Value; if performed in Open_List g The value update steps; if a child node is determined to be an obstacle, then that child node is ignored; S35. Repeat the above process until the destination is found; when the destination is found, backtrack the path node set, and the path node set with the minimum overall cost is the optimal path.

5. The automatic cable laying method in a three-dimensional environment according to claim 1, characterized in that, Step S41 specifically includes: S411. According to the theory of elastic rods, the cable is regarded as a slender rod with its axial dimension much larger than its radial dimension; the cable centerline is a smooth curve of second order or higher, passing through the center of the cross section; the cable has no shear deformation, and its cross section remains unchanged before and after deformation, always being a rigid cross section; the cable tensile deformation and initial deformation are ignored; the influence of each layer of the cable is not considered, and it is regarded as an isotropic elastic rod. S412. Based on the theory of elastic rods, the spatial shape of a cable consists of its centerline position and cross-sectional shape; the centerline position of the cable is determined by a vector... Representation; cross section and cross section The positional relationship between the two sections includes movement along the centerline and rotation between the sections; when the movement distance s is small enough, the relationship between the two sections can be regarded as rotation about a fixed point, which is represented by the direction cosine matrix. S413. The attitude of the cross section is represented by Euler parameters, and the direction cosine matrix is ​​expressed by Euler parameters as follows: S414. Based on the finite element method, the cable is divided into... The nth node is connected to adjacent nodes as a unit. Linear interpolation using Euler parameters within the unit yields the discretized nth node. The position and direction cosine matrix of each node is represented as follows: 。 6. The automatic cable laying method in a three-dimensional environment according to claim 1, characterized in that, Step S42 specifically includes: S421. Establish the potential energy equation for the cable. Including gravitational potential energy Bending potential energy Reversing potential energy ; S422. Using the discrete point potential energy equation of the cable as the objective function, Euler parameters as variables, and the boundary condition locations and Euler parameters as constraints, establish an optimization model for the cable model, as shown in the following expression: S423. Select initial point Set termination conditions Set the number of iterations ; S424, Construction Point Depart, choose a search direction , so that the objective function Decrease; S425, from Departure Find the appropriate amount of movement in the direction To obtain a satisfactory descent in that direction, Called a point Along the search direction Step size; S426, Order ,if If the iteration count is increased by 1, then execution continues from step S422; if at the iteration point Place, If the minimum value is reached, the algorithm stops and outputs the minimum point. ,Mode This is called the termination condition.

7. The automatic cable laying method in a three-dimensional environment according to claim 1, characterized in that, Step S43 specifically includes: S431. Data points are spatial points that must be traversed during cable routing, based on adjacent data points. , Construct a parametric cubic spline curve between two points, and use the vector form of the equation when constructing the curve equation; S432, in space For each data point, a piecewise fitting is performed based on adjacent data points to sequentially construct a cubic spline curve of parametric parameters between adjacent points, resulting in a total of [number missing]. A curve, by , The two points constitute the first The cubic polynomial parametric vector equation of the curve segment can be expressed as: S433. Solve for the tangent vector by utilizing the connection between adjacent curve segments. Level smoothness, i.e. , The equation is obtained as follows: S434. The established tangent vector equation system is a linear equation system, and the coefficient matrix of the equation system is a tridiagonal matrix. The linear equation system is solved using the chasing method. The chasing method first performs LU decomposition on the coefficient matrix, decomposing the coefficient matrix into the product of the lower triangular matrix L and the upper triangular matrix U. Finally, the equation system is solved by two back substitutions.

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