Gradient Voronoi porous shoe insole modeling method based on plantar biomechanics

Abstract

The invention discloses a gradient Voronoi porous shoe insole modeling method based on plantar biomechanics, and belongs to the field of porous structure design, and the method comprises the steps: S1, mapping an entity shoe insole stress field in a static standing state of a human body into Voronoi site distribution in a shoe insole model design domain, generating a Voronoi diagram in gradient distribution on the macroscopic level; s2, mapping the pressure field of the human body in the static standing state into the radius of each support rod with the target density of the model so as to control the radius of each support rod; and S3, taking the Voronoi diagram as a porous structure skeleton, generating a Voronoi strut structure based on an implicit surface modeling technology, and generating the gradient variable-radius Voronoi strut shoe insole with a continuous and smooth boundary through a fairing algorithm. According to the method, the porous shoe insole with gradient mechanical properties is generated based on plantar pressure distribution, the plantar peak force is reduced, meanwhile, the human foot pressure is more uniformly distributed, and meanwhile, mechanical-driven gradient porous shoe insole modeling is achieved.

Description

Technical Field

[0001] The invention relates to a modeling method, in particular to a gradient Voronoi porous shoe midsole modeling method based on plantar biomechanics. Background Art

[0002] With the exponential rise in the global prevalence of diabetes in the 21st century, diabetic foot ulcers (DFUs), as one of the most serious microvascular complications, have become a major challenge in the field of public health. In the prevention and treatment of diabetic foot ulcers, abnormal plantar pressure distribution is the core biomechanical factor that induces soft tissue damage. To address this issue, porous shoe midsole technology that can effectively reduce plantar peak pressure has attracted widespread attention from academia and industry. The gradient Voronoi porous shoe midsole, designed based on the principles of plantar biomechanics, analyzes the individualized plantar pressure distribution characteristics of patients and customizes an adaptive gradient Voronoi porous structure. This can significantly reduce plantar peak pressure and balance foot pressure distribution, thereby improving the condition of foot ulcers in diabetic patients.

[0003] The Voronoi porous structure, with its unique natural morphological characteristics, geometric continuity, and high controllability, demonstrates significant advantages in the design of porous shoe midsoles. Based on the Tekscan plantar pressure sensing system, the plantar pressure distribution of different patients can be accurately acquired. Finite element analysis is used to simulate plantar pressure to obtain the stress field of the shoe midsole. The density field of the Voronoi site is controlled based on the stress distribution, forming a porosity gradient at the macro level. At the cell level, the radius of each Voronoi strut is controlled based on the stress distribution, precisely controlling the density field. Furthermore, curvature-continuous topology optimization (operator construction in Riccis flow and geometric analysis) eliminates interference between strut connections, and a smoothing function is combined to achieve continuous transitions.

[0004] Traditional non-mechanically driven porous shoe midsoles have two main technical problems: first, it is impossible to accurately control the porous structure according to the patient's plantar pressure characteristics, and the reliance on Boolean clipping methods further exacerbates the lack of boundary adaptability; second, there are geometric discontinuities at the strut connections generated by traditional Boolean operations. This non-smooth transition will cause local stress concentration, making it impossible to match the patient's complex plantar pressure distribution characteristics, ultimately significantly reducing wearing comfort. Summary of the Invention

[0005] The purpose of the present invention is to provide a gradient Voronoi porous shoe midsole modeling method based on plantar biomechanics to solve the two technical problems mentioned in the above background technology regarding traditional non-mechanically driven porous shoe midsoles.

[0006] To achieve the above objectives, the specific plan is as follows:

[0007] A gradient Voronoi porous shoe midsole modeling method based on plantar biomechanics comprises the following steps:

[0008] S1, macro gradient control: The stress field of the solid shoe midsole in the static standing state of the human body is mapped to the Voronoi site distribution within the design domain of the shoe midsole model, and a Voronoi diagram of the gradient distribution is generated at the macro level to control the mechanical property gradient of the porous shoe midsole at the macro level;

[0009] S2: Micromechanical Adaptation: Mapping the foot stress field in a static standing state to the Voronoi strut radius of the model's target density, precisely controlling the radius of each strut and the mechanical property gradient of the porous shoe midsole at the cell level.

[0010] S3: Geometric continuity guarantee: The Voronoi diagram is used as the skeleton of the porous structure, and the Voronoi strut structure is generated based on implicit surface modeling technology. The smoothing algorithm is combined with implicit surface modeling to construct a gradient Voronoi porous shoe midsole with adaptive radius change, smooth boundaries and continuous gradient.

[0011] Furthermore, in step S1, the method for obtaining the stress field of the physical shoe midsole is: obtaining the patient's plantar pressure data through a plantar pressure measuring device, using the pressure data and the physical shoe midsole as input sources, inputting them into the finite element analysis software Abaqus, setting the TPU material parameters, generating the target stress field and saving it in a file.

[0012] Furthermore, in step S1, the method for generating the Voronoi diagram is as follows: the stress magnitude of each cell is obtained by calculating the average value of the stress nodes in each cell by generating a three-dimensional Voronoi diagram of random points, the stress-density mapping model is obtained by the Gibson-Ashby model and the target density of the cell is obtained, a weight function is constructed based on the target density, and the gradient site distribution driven by the stress field is obtained by combining the probability proportional sampling measurement to realize the construction of the weighted Voronoi diagram.

[0013] Furthermore, the plantar pressure measuring device is a HR Mat; the user stands on the plantar pressure measuring device and starts measuring after waiting for the data to stabilize for 5 seconds. The measured data is acquired and analyzed by the F-Scan plantar pressure system and the plantar pressure data is displayed in real time.

[0014] Furthermore, the mass density of the TPU material parameter is 1.25E-9t / mm 3 , Young's modulus is 26MPa, and Poisson's ratio is 0.46.

[0015] Furthermore, the steps of constructing the Voronoi diagram include:

[0016] S11: A set of random seed points Randomly distributed in the design domain, set the number of P to 4000; the current site p i Make a perpendicular bisector with other sites to obtain a finite number of intersecting surfaces, thereby obtaining the Voronoi cell V i , and the Voronoi cell V i The set of 3D Voronoi diagrams

[0017] S12: Grid the design domain and set the grid step size to 0.2 mm. The implicit surface in 3D space is defined as:

[0018] {q∈R 3 |f(q)=α}

[0019] S13: Cell V i The stress is recorded at the candidate site p i Department:

[0020]

[0021] S14: Select 2000 sites from the 4000 candidate sites as Voronoi sites by probability proportional sampling:

[0022]

[0023] S15: Calculate weights

[0024] w i =ω i V pi

[0025] S16: Calculate density ω i :

[0026]

[0027] Furthermore, step S2 includes the following sub-steps:

[0028] S21: Calculate the target relative density ρ′ of the cell according to the relative density calculation formula i and the actual relative density ρ i The ratio ρ′ i / ρ i , construct the weight function

[0029]

[0030] S22, establish a potential function model by calculating the distance between the grid points and the Voronoi skeleton line in three-dimensional space:

[0031] f(q)=(q-vp l)·n i

[0032] S23, weight the potential function f(q) of the skeleton line:

[0033]

[0034] Furthermore, step S3 includes the following sub-steps:

[0035] S31, the weighted potential function is applied to all grid points, and a smooth transition is achieved at the intersection through the Ricci flow and operator construction in geometric analysis:

[0036] F ve (q)=(F v (q) t +F(q) t ) 1 / t

[0037] S32, by using the smoothing function to modify the potential value fusion function, the connection between the rods is smoother. The smoothing function expression is:

[0038]

[0039] S33, reconstruct the potential function grid through the Marching Cubes algorithm to complete the modeling of the gradient Voronoi porous shoe midsole.

[0040] In summary, the present invention has the following beneficial effects compared to the prior art:

[0041] (1) The present invention provides a gradient Voronoi porous shoe midsole modeling method based on plantar biomechanics, which maps the plantar stress field of a physical shoe midsole into a Voronoi site distribution within the shoe midsole design domain. The gradient mechanical properties of the Voronoi porous shoe midsole are regulated based on the plantar pressure distribution of the patient at a macro level, thereby achieving personalized customization of the elastic modulus of the porous shoe midsole, effectively reducing the plantar peak pressure, and improving the uneven plantar pressure distribution.

[0042] (2) The present invention provides a gradient Voronoi porous shoe midsole modeling method based on plantar biomechanics, which maps the plantar stress field of the solid shoe midsole to the radius of the Voronoi strut within the shoe midsole design domain, and adjusts the radius size of the adaptive gradient variable radius Voronoi strut structure at the cell level. Under the premise of unchanged relative density, it further reduces the plantar peak pressure and balances the uneven distribution of plantar pressure, thereby alleviating the foot ulcer condition of diabetic patients. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0044] Figure 1 is a diagram of method steps of an embodiment of the present invention;

[0045] Figure 2 is a detailed flow chart of an embodiment of the present invention;

[0046] Figure 3 Schematic diagram of weighted sites for generating density gradients through probability proportional sampling according to an embodiment of the present invention;

[0047] Figure 4 is a density gradient weighted Voronoi diagram generated by an embodiment of the present invention;

[0048] Figure 5 is a schematic diagram of a single variable radius Voronoi strut generated by an embodiment of the present invention;

[0049] Figure 6 is a schematic diagram of a variable radius Voronoi cell generated by an embodiment of the present invention;

[0050] Figure 7 This is the gradient Voronoi porous shoe midsole model based on plantar biomechanics that is ultimately generated by the embodiment of the present invention. DETAILED DESCRIPTION

[0051] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention 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.

[0052] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form can also include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0053] Unless otherwise specifically stated, the relative arrangement of the parts and steps, numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to actual proportional relationships. The techniques, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the techniques, methods and equipment should be considered as part of the authorized specification. In all examples shown and discussed herein, any specific values should be interpreted as being merely exemplary and not as limitations. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following figures, and therefore, once an item is defined in one figure, it does not need to be further discussed in subsequent figures.

[0054] See also Figures 1 to 2 As shown, the present invention provides a gradient Voronoi porous shoe midsole modeling method based on plantar biomechanics, comprising the steps of:

[0055] S1, macro gradient control: Map the stress field of the physical shoe midsole in the static standing state of the human body to the distribution of Voronoi sites in the design domain of the shoe midsole model, generate a Voronoi diagram of gradient distribution at the macro level, and control the mechanical property gradient (porosity gradient) of the porous shoe midsole from the macro level. Among them, the physical shoe midsole model and the tester's plantar pressure distribution are input and the stress field is obtained through finite element analysis. The stress field of the shoe midsole is mapped to the distribution of Voronoi sites in the new design domain as follows Figure 3 As shown, the Voronoi diagram of the generated gradient distribution is as follows Figure 4 shown.

[0056] Specifically, the macro-gradient control of the porosity gradient of the Voronoi porous shoe midsole is divided into the following two steps:

[0057] (1) In order to obtain the plantar stress field, it is necessary to obtain the patient's plantar pressure data through the plantar pressure measurement device, and use the pressure data and the physical shoe midsole as input sources to input into the finite element analysis software Abaqus, set the TPU material parameters, generate the target stress field and save it to a file.

[0058] The specific implementation steps are:

[0059] The HR Mat, a plantar pressure measuring device, is used for measurement. The HR Mat has a thin, flexible pad with an embedded pressure sensor that can accurately measure the pressure distribution on the sole of the foot. The actual effective area of the plantar pressure sensing pad is approximately 48.77 × 44.70 cm 2The pressure sensor on the mat has a total of 8448 sensing elements that can measure static and dynamic plantar pressure with a sampling frequency of 185Hz. The mat is placed on a flat ground and the user stands upright on the mat to obtain real-time pressure.

[0060] Since the pressure data obtained by the pressure sensor changes in real time, to ensure data accuracy, the user needs to maintain an upright and relaxed posture and wait for the data to stabilize for 5 seconds before starting the measurement. The mat is connected to a computer, and the F-Scan plantar pressure system acquires, analyzes, and displays plantar pressure data in real time. The acquired plantar pressure data and a physical shoe midsole model are input into the finite element analysis software ABAQUS. TPU is selected as the printing material with a mass density of 1.25E-9t / mm3, a Young's modulus of 26MPa, and a Poisson's ratio of 0.46. The stress field within the design domain is obtained through finite element analysis.

[0061] (2) Complete the mapping of stress field to site distribution and construct a three-dimensional Voronoi diagram generated by weighted sites; generate a three-dimensional Voronoi diagram of random points and calculate the average value of the stress nodes in each cell to obtain the stress magnitude of each cell. The stress-density mapping model is obtained through the Gibson-Ashby model and the target density of the cell is obtained. The weight function is constructed based on the target density, and the gradient site distribution driven by the stress field is obtained by combining the probability proportional sampling measurement to realize the construction of the weighted Voronoi diagram.

[0062] The specific implementation steps are:

[0063] A set of random seed points Randomly distributed in the design domain, the point set P is called candidate sites, and the number of P is set to 4000; the current site p i Make a perpendicular bisector with other sites to obtain a finite number of intersecting surfaces. The unit body wrapped by these surfaces is called site p i Voronoi cell V i , the set of all cells in the design domain is called the three-dimensional Voronoi diagram

[0064] The design domain is gridded and the grid step is set to 0.2 mm. The implicit surface in three-dimensional space is defined as:

[0065] {q∈R 3 |f(q)=α}

[0066] Where q represents the coordinates of the three-dimensional space grid point, f(q) is the potential function, α is the equipotential value, and the radius of the support rod designed in the embodiment of the present invention is 1.2 mm, that is, the equipotential value α is equal to 1.2 mm; implicit surface modeling is achieved by dividing the model into a finite number of three-dimensional space grids and calculating the grid point q through the potential function.p The potential value α k , when α k When α is greater than α, the grid points are outside the closed surface. k When α is less than α, the grid points are located inside the closed surface. k When it is equal to α, the grid points are exactly located on the closed surface.

[0067] The cell V i The stress is recorded at the candidate site p i The calculation formula is as follows:

[0068]

[0069] in, It is site p i The magnitude of the Mises stress at is the Voronoi cell V i The stress magnitude of the internal stress node, n i is the Voronoi cell V i The number of internal stress nodes.

[0070] Taking into account the porosity of the shoe midsole, 2000 sites were selected from 4000 candidate sites as Voronoi sites through probability proportional sampling to achieve gradient control of site distribution at the macro level. The probability proportional sampling strategy is as follows:

[0071]

[0072] in, Indicates site p i The weight of R represents random sampling to generate a number between 0 and 1, S i Indicates site p i The sampling fraction of the final generated site is as follows Figure 3 shown.

[0073] Weight The density ω is calculated by Mises stress and relative density mapping model. i The calculation formula is as follows:

[0074]

[0075] Among them, σ p Indicates the ultimate strength of the material.

[0076] Weight The calculation formula is as follows:

[0077]

[0078] Among them, V piRepresents cell V i volume.

[0079] S2, micromechanical adaptation: Mapping the foot stress field of the human body in a static standing state to the Voronoi strut radius of the model target density, precisely controlling the radius of each strut and the mechanical property gradient of the porous shoe midsole at the cell level.

[0080] In other words, the stress field obtained by S1 is mapped to the radius of the struts of the target density of the model, and the radius of each strut is precisely controlled at the cell level. The stress drives the radius of a single strut to change as follows: Figure 5 As shown, the stress drives the radius of a single cell to change as Figure 6 As shown, the specific implementation steps are:

[0081] S21, calculate the target relative density ρ′ of the cell according to the relative density calculation formula i and the actual relative density ρ i The ratio ρ′ i / ρ i , construct the weight function The calculation formula is as follows:

[0082]

[0083] S22, establish a potential function model by calculating the distance between the grid points and the Voronoi skeleton line in three-dimensional space:

[0084] f(q)=(q-vp l )·n i

[0085] Among them, vp l represents the vertices of the Voronoi skeleton, n i The unit normal vector of the grid point pointing perpendicular to the Voronoi skeleton.

[0086] S23, weight the potential function f(q) of the skeleton line, and the calculation formula is as follows:

[0087]

[0088] Where F(q) represents the weighted potential function.

[0089] S3, Geometric Continuity Assurance: Using the Voronoi diagram as the porous structure skeleton, implicit surface modeling techniques are used to generate the Voronoi strut structure. A smoothing algorithm is then used to generate a gradient-variable-radius Voronoi strut midsole with smooth and continuous boundaries. By combining the smoothing algorithm with implicit surface modeling, a gradient-variable-radius porous Voronoi strut midsole with adaptive radius variation, smooth and continuous boundaries is constructed.

[0090] The specific implementation steps are:

[0091] The three-dimensional Voronoi diagram is used as the porous structure skeleton, and the Voronoi strut structure is generated based on the implicit surface modeling technology. The gradient variable radius Voronoi strut midsole with continuous and smooth boundaries is generated by the smoothing algorithm. Figure 7 As shown, step S3 includes sub-steps:

[0092] S31, the weighted potential function is applied to all grid points, and the smooth transition at the intersection is achieved through the Ricci superellipse fusion operator:

[0093] F ve (q)=(F v (q) t +F(q) t ) 1 / t

[0094] Among them, F v (q) is the potential function of the Voronoi corner, F(q) is the potential function of the Voronoi skeleton, t is the adjustment factor, and when t = 1, it is a narrow fusion operation; when t approaches infinity, the fusion operation is similar to the Boolean union operation. In this design, t is set to 2;

[0095] S32, by using the smoothing function to modify the potential value fusion function, the connection between the rods is smoother. The smoothing function expression is:

[0096]

[0097] S33, reconstruct the potential function grid using the Marching Cubes algorithm to complete the modeling of the gradient Voronoi porous shoe midsole, setting the equipotential value to 1.2mm and the grid step size to 0.2mm.

[0098] The Marching Cubes algorithm is a three-dimensional equipotential surface extraction algorithm. It uses interpolation to calculate the corner points of the equipotential surface and the voxel edge to generate a triangular mesh. The grid divided in step S3 is replaced with the voxel grid in the Marching Cubes algorithm. The equipotential surface is directly extracted through the equipotential values of the grid points, thus finally completing the construction of the three-dimensional gradient Voronoi porous shoe midsole.

[0099] The present invention realizes the modeling of the gradient Voronoi porous shoe midsole based on plantar biomechanics, effectively reduces the peak plantar pressure, realizes the smooth continuity of the gradient Voronoi porous shoe midsole boundary, balances the foot pressure distribution, and thus improves the foot ulcer condition of diabetic patients.

[0100] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A gradient Voronoi porous shoe midsole modeling method based on plantar biomechanics, characterized in that: Including steps: S1, macro gradient control: The stress field of the solid shoe midsole in the static standing state of the human body is mapped to the Voronoi site distribution within the design domain of the shoe midsole model, and a Voronoi diagram of the gradient distribution is generated at the macro level to control the mechanical property gradient of the porous shoe midsole at the macro level; S2: Micromechanical Adaptation: Mapping the foot stress field in a static standing state to the Voronoi strut radius of the model's target density, precisely controlling the radius of each strut and the mechanical property gradient of the porous shoe midsole at the cell level. S3: Geometric continuity guarantee: The Voronoi diagram is used as the skeleton of the porous structure, and the Voronoi strut structure is generated based on implicit surface modeling technology. The smoothing algorithm is combined with implicit surface modeling to construct a gradient Voronoi porous shoe midsole with adaptive radius change, smooth boundaries and continuous gradient.

2. The gradient Voronoi porous shoe midsole modeling method based on plantar biomechanics according to claim 1 is characterized in that: In step S1, the method for obtaining the stress field of the physical shoe midsole is as follows: obtaining the patient's plantar pressure data through a plantar pressure measurement device, using the pressure data and the physical shoe midsole as input sources, inputting them into the finite element analysis software Abaqus, setting the TPU material parameters, generating the target stress field and saving it in a file.

3. The gradient Voronoi porous shoe midsole modeling method based on plantar biomechanics according to claim 1, characterized in that: In step S1, the Voronoi diagram is generated by calculating the average value of the stress nodes in each cell through a three-dimensional Voronoi diagram generated by random points to obtain the stress magnitude of each cell, obtaining a stress-density mapping model through a Gibson-Ashby model and obtaining the target density of the cell, constructing a weight function based on the target density, and combining probability proportional sampling measurement to obtain the gradient site distribution driven by the stress field to realize the construction of a weighted Voronoi diagram.

4. The gradient Voronoi porous shoe midsole modeling method based on plantar biomechanics according to claim 2, characterized in that: The plantar pressure measurement device is an HR Mat; the user stands on the plantar pressure measurement device and waits for the data to stabilize for 5 seconds before starting the measurement. The measurement data is acquired and analyzed by the F-Scan plantar pressure system and the plantar pressure data is displayed in real time.

5. The gradient Voronoi porous shoe midsole modeling method based on plantar biomechanics according to claim 2, characterized in that: The mass density of the TPU material parameter is 1.25E-9t / mm 3 , Young's modulus is 26MPa, and Poisson's ratio is 0.

46.

6. The gradient Voronoi porous shoe midsole modeling method based on plantar biomechanics according to claim 3, characterized in that: The steps of constructing the Voronoi diagram include: S11: A set of random seed points Randomly distributed in the design domain, set the number of P to 4000; the current site p i Make a perpendicular bisector with other sites to obtain a finite number of intersecting surfaces, thereby obtaining the Voronoi cell V i , and the Voronoi cell V i The set of 3D Voronoi diagrams S12: Grid the design domain and set the grid step size to 0.2 mm. The implicit surface in 3D space is defined as: {q∈R 3 |f(q)=α} S13: Cell V i The stress is recorded at the candidate site p i Department: S14: Select 2000 sites from the 4000 candidate sites as Voronoi sites by probability proportional sampling: S15: Calculate weights w i =ω i V pi S16: Calculate density ω i :

7. The gradient Voronoi porous shoe midsole modeling method based on plantar biomechanics according to claim 1, characterized in that: Step S2 includes the following sub-steps: S21: Calculate the target relative density ρ′ of the cell according to the relative density calculation formula i and the actual relative density ρ i The ratio ρ′ i / ρ i , construct the weight function S22, establish a potential function model by calculating the distance between the grid points and the Voronoi skeleton line in three-dimensional space: f(q)=(q-vp l )·n i S23, weight the potential function f(q) of the skeleton line:

8. The gradient Voronoi porous shoe midsole modeling method based on plantar biomechanics according to claim 1, characterized in that: Step S3 includes the following sub-steps: S31, the weighted potential function is applied to all grid points, and a smooth transition is achieved at the intersection through the Ricci flow and operator construction in geometric analysis: F ve (q)=(F v (q) t +F(q) t ) 1 / t S32, by using the smoothing function to modify the potential value fusion function, the connection between the rods is smoother. The smoothing function expression is: S33, reconstruct the potential function grid through the Marching Cubes algorithm to complete the modeling of the gradient Voronoi porous shoe midsole.

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