A new foot-shoe three-dimensional numerical model construction method and system

Abstract

This invention discloses a novel method and system for constructing a three-dimensional numerical model of the foot and shoe. The method first acquires foot and shoe data from a subject wearing footwear in three postures: toe-landing, static standing, and heel-landing, using spiral CT scans. Based on the acquired scan data, and after mesh generation and material property assignment, a three-dimensional finite element numerical model of the foot and shoe is established. Static simulations are performed by inputting different ligament elastic moduli and Poisson's ratio parameters into the three-dimensional finite element numerical model of the foot and shoe, and setting boundary conditions for the corresponding postures, to obtain simulated values ​​of peak pressure on the sole and shoe sole and deformation in specific areas. Simultaneously, physical tests are conducted to obtain measured values. Error analysis is performed between the simulated and measured values, and the optimal set of parameters with the smallest total error is selected by adjusting the ligament parameters to construct a standard three-dimensional numerical model of the foot and shoe. This invention combines multi-posture mechanical response and ligament parameter optimization to achieve high-precision verification and correction of the foot and shoe model.

Description

Technical Field

[0001] This invention relates to the technical field of biomechanical modeling and simulation, and in particular to a novel method and system for constructing a three-dimensional numerical model of foot-shoe based on multi-posture mechanical response and ligament parameter optimization. Background Technology

[0002] With the rapid development of computer simulation technology, finite element analysis has been widely applied in foot and ankle biomechanics research and footwear design optimization. Researchers can establish high-precision three-dimensional numerical models of the foot and shoe to simulate the interactions between foot bones, soft tissues, and the sole at different gait cycles, thereby predicting key mechanical indicators such as plantar pressure distribution, sole cushioning performance, and ligament stress. This simulation method has significant theoretical guidance and practical application value for the design of diabetic footwear, the improvement of athletic shoe performance, and the development of orthotics.

[0003] Currently, conventional methods for establishing three-dimensional numerical models of the foot and shoe mainly employ static bipedal standing postures for model verification. The construction process typically includes: first, obtaining tomographic image data by scanning the human foot and footwear using a spiral CT scanner; then, setting the initial and boundary conditions for the foot and shoe soles when the human is in a static bipedal standing position; performing numerical simulation calculations of the foot-shoe static standing posture to obtain the peak plantar pressure in different areas of the foot and the peak sole pressure in different areas of the shoe; simultaneously conducting pressure plate tests on the human body wearing shoes while in a static bipedal standing position to obtain corresponding measured pressure data; and finally, performing error analysis between the simulation and test data to verify and correct the three-dimensional numerical model of the foot and shoe.

[0004] However, existing foot-shoe numerical models still have the following technical shortcomings in the analysis of foot and shoe stress and deformation:

[0005] First, the model validation methods are simplistic and lack multi-dimensional comparisons of mechanical responses. Current methods for constructing foot-shoe numerical models typically rely solely on macroscopic comparisons of peak plantar pressure in different areas of the foot and shoe sole, or only static validation under a single posture (such as bipedal standing). While this validation approach can reflect certain pressure distribution trends, it struggles to comprehensively reveal the impact of changes in internal structural parameters such as phalanges and ligaments on external foot deformation under different postures (such as heel strike or toe strike), failing to guarantee the model's generalization performance and prediction accuracy under various working conditions.

[0006] Second, the setting of ligament parameters lacks precise calibration basis. As a key soft tissue structure for maintaining joint stability and support, the material properties of foot ligaments significantly impact simulation results. Current techniques often rely on simplified linear elastic model parameters when setting ligament parameters, lacking calibration steps for individual-specific data. Because Poisson's ratio and elastic modulus vary among individuals, directly applying simplified model parameters often leads to significant deviations between the simulation model and reality, affecting the accuracy and reliability of model predictions.

[0007] Therefore, there is an urgent need for a novel method for constructing three-dimensional numerical models of foot and shoe that can verify the mechanical response in multiple postures and achieve precise optimization of ligament parameters, so as to obtain high-precision three-dimensional numerical models of foot and shoe to meet the practical needs of foot and ankle biomechanical research and footwear design optimization. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of the prior art and provide a novel method and system for constructing a three-dimensional numerical model of the foot and shoe. By integrating the mechanical response data of three typical gait postures—toe landing, static standing, and heel landing—and combining the systematic traversal of ligament material parameters with multi-source error analysis, the invention achieves high-precision construction and reliability verification of the three-dimensional numerical model of the foot and shoe.

[0009] To achieve the above objectives, the technical solution provided by this invention is as follows:

[0010] A novel method for constructing a three-dimensional numerical model of a foot and shoe includes:

[0011] Using a spiral CT scanner, scan data of the subject's feet and footwear were collected in three postures: toe-toe, static standing, and heel-to-toe.

[0012] Based on the acquired scan data, three-dimensional geometric models of the foot and shoe are constructed for the toe-landing posture, static standing posture, and heel-landing posture, respectively; the three-dimensional geometric models of the foot and shoe include foot bones, soft tissues, ligaments, and shoe components;

[0013] The constructed three-dimensional geometric model was meshed and material properties were assigned to establish a three-dimensional finite element numerical model of foot-shoe; among which, the elastic modulus and Poisson's ratio of the ligament were used as parameters to be optimized.

[0014] Input the ligament elastic modulus and Poisson's ratio parameters into the three-dimensional finite element numerical model of foot-shoe, and set the initial conditions and boundary conditions to perform static simulation, and obtain the simulated values ​​of the peak pressure of the foot sole, the peak pressure of the shoe sole, and the total deformation of a specific area;

[0015] Physical tests were conducted on subjects wearing footwear in the same posture to obtain the measured peak value of plantar pressure, the measured peak value of shoe sole pressure, and the measured value of total deformation in a specific area.

[0016] Error analysis was conducted by combining the simulated and measured values ​​of peak plantar pressure, peak shoe pressure, and total deformation in a specific area. Based on the principle of minimizing total error, the optimal combination of ligament elastic modulus and Poisson's ratio parameters was selected to construct a standard foot-shoe three-dimensional numerical model.

[0017] Furthermore, initial and boundary conditions are set according to the actual force conditions of each posture, including:

[0018] Restraining the upper surface of the foot bones and the upper surface of the foot soft tissues;

[0019] A vertically upward ground reaction force is applied to the bottom of the floor, and the magnitude of the ground reaction force is set to half the subject's body weight;

[0020] The foot bones and soft tissues are bound together; the insole, upper, midsole and outsole are bound together; and the attachment points of the foot bones and ligaments are coupled together.

[0021] The frictional contact between the foot and the upper of the shoe, the sole of the foot and the insole, and the sole of the shoe and the ground are set, with the coefficient of friction set to 0.6.

[0022] Furthermore, during static simulation, the peak plantar pressure values ​​of the foot regions T1, T2, 3, 4, 5, M1, M2, M3, M4, M5, MF, MH, and LH, the peak shoe sole pressure values ​​of the shoe sole regions T1, T2, 3, 4, 5, M1, M2, M3, M4, M5, MF, MH, and LH, and the total deformation simulation values ​​of the shoe sole region M3 in the toe-landing posture, the shoe sole region MF in the static standing posture, and the shoe sole region MH in the heel-landing posture were obtained.

[0023] Furthermore, when subjects wore footwear and underwent physical testing in the same posture, the peak values ​​of the measured plantar pressure in the foot regions T1, T2, 3, 4, 5, M1, M2, M3, M4, M5, MF, MH, and LH, and the peak values ​​of the measured shoe sole pressure in the shoe sole regions T1, T2, 3, 4, 5, M1, M2, M3, M4, M5, MF, MH, and LH were measured using pressure plates and patch-type plantar pressure sensors in three postures. At the same time, the total deformation of the shoe sole region M3 when the toes touched the ground, the shoe sole region MF when standing statically, and the shoe sole region MH when the heel touched the ground was measured using CT scanning or three-dimensional scanning technology.

[0024] Furthermore, error analysis was conducted by combining the simulated and measured values ​​of peak plantar pressure, peak shoe sole pressure, and total deformation in a specific area. The process for calculating the total error is as follows:

[0025] Calculate the average error of peak plantar pressure in toe-landing, static standing, and heel-landing postures respectively. , , The formula for obtaining the answer is as follows:

[0026] ;

[0027] in, Indicates the area code; This represents the average error of the peak plantar pressure under the corresponding posture. Indicates the first position under the corresponding attitude Simulated plantar pressure values ​​for the region Indicates the first position under the corresponding attitude Measured plantar pressure values ​​for the region;

[0028] Calculate the average error of the peak sole pressure under the toe-landing posture, static standing posture, and heel-landing posture respectively. , , The formula for obtaining the answer is as follows:

[0029] ;

[0030] This represents the average error of the peak pressure of the sole under the corresponding posture. Indicates the first position under the corresponding attitude Simulated values ​​of sole pressure in the region Indicates the first position under the corresponding attitude Measured values ​​of sole pressure in the area;

[0031] Calculate the percentage difference between the simulated and measured values ​​of the total deformation of the sole region M3 in the toe-landing posture, the sole region MF in the static standing posture, and the sole region MH in the heel-landing posture, respectively, relative to the measured values; this is the corresponding relative error. , , The formula for obtaining the answer is as follows:

[0032] ;

[0033] This represents the relative error within the corresponding region of the corresponding attitude. This represents the simulated value of the corresponding total deformation. This represents the measured value of the corresponding total deformation.

[0034] Calculate the total average error of the peak plantar pressure :

[0035] ;

[0036] Calculate the total average error of the peak pressure of the sole. :

[0037] ;

[0038] Calculate the total relative error of the total deformation in the sole area. :

[0039] ;

[0040] Calculate the total error:

[0041] .

[0042] Furthermore, when collecting scanning data of the subject's feet and shoes while the subject was wearing footwear and in a toe-landing state, the angle between the subject's sole and the ground was controlled at 20°.

[0043] When collecting scan data of the subject's feet and shoes while the heel was on the ground, the angle between the sole of the foot and the ground was controlled to be -10°.

[0044] Furthermore, the combination of ligament elastic modulus and Poisson's ratio parameters was selected within a physiologically reasonable range. The ligament elastic modulus was based on 260 MPa and varied by ±10%, while the Poisson's ratio was selected within the range of 0.4 to 0.495. Nine sets of parameter combinations were formed by pairwise combinations and then tested.

[0045] Furthermore, the ligaments include the metatarsophalangeal joint collateral ligament between the metatarsals and phalanges, the interphalangeal joint collateral ligament between the phalanges, and the talocalcaneal interosseous ligament between the talus and calcaneus.

[0046] Furthermore, to achieve the above objectives, the present invention also provides a novel foot-shoe three-dimensional numerical model construction system for implementing the aforementioned novel foot-shoe three-dimensional numerical model construction method, comprising:

[0047] The multi-posture data acquisition module is used to acquire scan data of the subject's feet and footwear in three postures: toe-on, static standing, and heel-on, using a CT scanning device.

[0048] The three-dimensional geometric modeling module is used to construct three-dimensional geometric models of the foot and shoe in the corresponding poses based on the scanned image data, and to perform mesh generation and material property assignment to establish a three-dimensional finite element numerical model of the foot and shoe.

[0049] The 3D finite element numerical modeling module is used to mesh and assign material properties to the constructed 3D geometric model, and to establish a 3D finite element numerical model of a foot-shoe.

[0050] The statics simulation module inputs the ligament elastic modulus and Poisson's ratio parameters into the three-dimensional finite element numerical model of the foot-shoe, and sets the initial conditions and boundary conditions to perform statics simulation, and obtains the simulated values ​​of the peak pressure of the foot sole, the peak pressure of the shoe sole, and the total deformation of a specific area.

[0051] The physical testing module is used to conduct physical tests on subjects wearing footwear in the same posture to obtain the measured peak value of plantar pressure, the measured peak value of shoe sole pressure, and the measured value of total deformation in a specific area.

[0052] The error analysis module is used to perform error analysis by combining the simulated and measured values ​​of the peak foot pressure, peak shoe pressure, and total deformation in a specific area to obtain the total error.

[0053] The parameter selection and model building module is used to select the combination of ligament elastic modulus and Poisson's ratio parameters that minimizes the total error, and to build a standard foot-shoe three-dimensional numerical model based on the optimal ligament parameters.

[0054] Compared with existing technologies, the principles and advantages of this technical solution are as follows:

[0055] 1. A collaborative method for constructing a three-dimensional numerical model of the foot-shoe system, integrating "multi-posture mechanical response and ligament parameter optimization," is proposed. This method decouples the mechanical responses of three typical gait postures: toe-landing, static standing, and heel-landing, and establishes a multi-objective parameter optimization process based on error fusion. This method integrates standardized settings of multi-posture mechanical boundary conditions, systematic traversal of ligament material parameters, and a joint verification mechanism for three types of responses: plantar pressure, sole pressure, and sole deformation. This enables the foot-shoe model to achieve higher accuracy in mechanical prediction and model reliability assessment compared to conventional verification methods. This method significantly reduces the errors in plantar pressure, sole pressure, and sole deformation between simulation and actual measurements, and systematically improves the model's generalization performance under different working conditions.

[0056] 2. A ligament material parameter optimization method based on parameter combination traversal and multi-source error analysis is adopted. This method does not require prior precise knowledge of the exact material properties of the ligament; it only requires traversal within its physiologically reasonable range (elastic modulus ±10% variation, Poisson's ratio 0.4-0.495). By comprehensively evaluating the errors of three types of mechanical responses—simulated and measured plantar pressure, shoe sole pressure, and shoe sole deformation—the optimal parameter combination is selected, enhancing adaptability to individual differences, measurement errors, and uncertainties in model simplification. Furthermore, the optimized ligament parameters are used as standard material properties to directly establish a high-precision foot-shoe numerical model, improving the problem of large deviations in simulation results caused by inaccurate ligament parameters in traditional methods.

[0057] 3. Specific measurements and comparisons were conducted on the deformation of the sole in the M3 region under toe-landing posture, the MF region under static standing posture, and the MH region under heel-landing posture. The key mechanical responses under these three postures were decomposed and verified, reducing the limitations of single-posture verification. For error assessment, a three-tiered index was constructed: total average error of plantar pressure, total average error of sole pressure, and total relative error of deformation. A unified total error evaluation standard was formed through weighted averaging, achieving comprehensive reliability quantification of the simulation model under different postures and mechanical response dimensions, thus overcoming the limitations of traditional methods that rely solely on comparing pressure peak values ​​in a single region. Attached Figure Description

[0058] 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 only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0059] Figure 1 This is a flowchart illustrating the principle of a novel foot-shoe three-dimensional numerical model construction method of the present invention.

[0060] Figure 2 This is a schematic diagram of the walking gait cycle;

[0061] Figure 3 A schematic diagram of the three-dimensional geometric model of the foot and shoe in three poses;

[0062] Figure 4 A schematic diagram showing the setting of boundary conditions for the three attitudes;

[0063] Figure 5 A schematic diagram of the T1, T2, 3, 4, 5, M1, M2, M3, M4, M5, MF, MH and LH regions of the sole of the foot and the sole of the shoe;

[0064] Figure 6 This is a schematic diagram of the error calculation process;

[0065] Figure 7 This is a connection block diagram of a novel foot-shoe three-dimensional numerical model construction system according to the present invention. Detailed Implementation

[0066] The present invention will be further described below with reference to specific embodiments:

[0067] like Figure 1 As shown in this embodiment, a novel method for constructing a three-dimensional numerical model of a foot and shoe includes the following steps:

[0068] S1. Select a healthy adult subject (weighing 70kg, foot length 265mm) and a pair of shoes (corresponding to European size 43). Using a spiral CT scanner (such as Siemens SOMATOM Definition Flash), collect scan data of the subject's foot and shoes in three postures: toe-on, static standing, and heel-on.

[0069] Among them, such as Figure 2 As shown,

[0070] Toe-landing posture: The angle between the subject's foot and the ground was controlled to be 20°. This angle corresponds to the push-off phase in the gait cycle. At this time, the ankle plantar flexor muscles are in a state of maximum activation, and the forefoot bears the main ground reaction force. This is the key posture for the biomechanical response of the foot-shoe system.

[0071] Static standing posture: The subject is controlled to stand naturally with both feet parallel to the ground and the body's center of gravity evenly distributed on both feet;

[0072] Heel strike posture: The angle between the subject's foot and the ground was controlled to be -10°. This angle corresponds to the initial landing phase in the gait cycle. At this time, the heel makes contact with the ground first, and the ankle joint is in a slightly dorsiflexed or neutral position. This is the key stage for impact transmission and cushioning.

[0073] The scan range extends from above the ankle joint to the toes, ensuring complete coverage of the foot's bones, soft tissues, and footwear structure.

[0074] S2. Based on the acquired scan data, construct three-dimensional geometric models of the foot and shoe for toe-landing posture, static standing posture, and heel-landing posture, respectively, as follows: Figure 3 As shown; the specific process of this step is as follows:

[0075] S2-1, Image Segmentation: Using threshold segmentation and region growing algorithms, extract foot bones, soft tissues, ligaments, and shoe components respectively;

[0076] S2-2, 3D Reconstruction: Based on the segmented 2D contour data, a 3D surface model of each component is generated through a surface reconstruction algorithm;

[0077] S2-3, Ligament Geometric Modeling: In Geomagic Studio or SolidWorks software, manually create the geometric model of key ligaments based on the ligament origin and insertion locations recorded in anatomical literature, including:

[0078] 1) Metatarsophalangeal joint collateral ligament: connects the head of each metatarsal bone to the base of the corresponding proximal phalanx;

[0079] 2) Interphalangeal joint collateral ligaments: connect the proximal and distal phalanges;

[0080] 3) Intertalacral ligament: connects the talus and calcaneus, located within the sinus tarsi;

[0081] S2-4. Model Assembly: Assemble the bones, soft tissues, ligaments, and footwear components according to their anatomical positions, ensuring that the spatial relationships between the components conform to the actual anatomical structure.

[0082] S3. Mesh the constructed three-dimensional geometric model and assign material properties to establish a three-dimensional finite element numerical model of foot-shoe; among which, the elastic modulus and Poisson's ratio of the ligament are used as parameters to be optimized.

[0083] In this step,

[0084] (1) Grid generation:

[0085] Skeleton: 10-node tetrahedral elements (C3D10) are used, with an element size of 1.5mm, and the density is locally reduced to 0.8mm in the joint contact area;

[0086] Soft tissue (skin, fat pad, plantar fascia): 8-node hexahedral elements (C3D8R) with an element size of 2.0 mm were used, and reduced integrals were employed to improve computational efficiency;

[0087] Ligaments: Truss units or beam units are used, with a unit length of 1.0 mm and a cross-sectional area set according to anatomical data (approximately 12 mm² for the metatarsophalangeal joint collateral ligament and approximately 25 mm² for the intercalcaneal ligament).

[0088] Footwear: The midsole and outsole use 8-node hexahedral units with a unit size of 2.0mm; the upper and insole use shell units (S4R), with the thickness set according to actual measurements.

[0089] (2) Assigning material properties:

[0090] Skeleton: Elastic modulus 7300MPa, Poisson's ratio 0.3, density 1.9g / cm³, considered as an isotropic linear elastic material;

[0091] Soft tissue: elastic modulus 1.15 MPa, Poisson's ratio 0.45, density 0.937 g / cm³;

[0092] Upper: Elastic modulus 11.76 MPa, Poisson's ratio 0.35, density 9.4 g / cm³;

[0093] Insole: Based on the constitutive model of Hyperfoam, μ1=-5.66MPa, α1=7.54, μ2=7.54MPa, α2=8.41, μ3=8.41MPa, α3=-1.91, μ4=-7.59E-06MPa, α4=-5.44, β1, β2, β3 and β4 are all 0, density 0.202g / cm³

[0094] Midsole: Adopts the constitutive model of Hyperfoam foam, with μ1=-1.98MPa, α1=5.89, μ2=2.59MPa, α2=6.66, μ3=0.01MPa, α3=-2.41, μ4=-7.77E-07MPa, α4=-6.80, β1, β2, β3, and β4 are all 0, and density is 0.15g / cm³.

[0095] Outsole: Adopts a superelastic Polynomial constitutive model, with C10 = -2.45 MPa, C01 = 5.08 MPa, C20 = -1.70 MPa, C11 = 6.02 MPa, C02 = -3.10 MPa, and D1 and D2 both being 0 MPa. -1 Density 0.119 g / cm³;

[0096] Ligament: The elastic modulus is set as the parameter to be optimized (baseline value 260MPa), and the Poisson's ratio is set as the parameter to be optimized (value range 0.4-0.495), and it is regarded as a linear elastic material.

[0097] (3) Definition of contact:

[0098] Between the sole and the insole: surface-to-surface contact, coefficient of friction 0.6, contact constraint is handled using the penalty function method;

[0099] Between the insole and the midsole: a tight, secure contact;

[0100] Between the upper and the midsole: a bonded contact;

[0101] Between the shoe upper and the foot: surface-to-surface contact, coefficient of friction 0.6;

[0102] Between the midsole and outsole: a bonded contact;

[0103] Between the outsole and the ground: surface-to-surface contact, coefficient of friction 0.6;

[0104] Between bone and soft tissue: binding contact;

[0105] Ligament and bone attachment points: coupling constraints.

[0106] (4) Ligament parameter combination settings:

[0107] Nine sets of ligament material parameter combinations were set for iterative calculation. The specific parameter settings are shown in Table 1.

[0108] Table 1. Ligament material parameter combination settings

[0109] Parameter combination number Elastic modulus E (MPa) Poisson's ratio ν 1 234 0.4 2 234 0.45 3 234 0.495 4 260 0.4 5 260 0.45 6 260 0.495 7 286 0.4 8 286 0.45 9 286 0.495

[0110] Among them, the elastic modulus of 260 MPa is the benchmark value for ligament materials reported in the literature, and 234 MPa and 286 MPa are the values ​​after reducing and increasing the benchmark value by 10%, respectively; Poisson's ratios of 0.4, 0.45, and 0.495 cover the reasonable range of values ​​for ligaments as water-rich fiber-reinforced soft tissue materials (close to incompressible materials but avoiding the volume lock-in problem in finite element calculations).

[0111] S4. Input the ligament elastic modulus and Poisson's ratio parameters into the three-dimensional finite element numerical model of foot-shoe, and set the initial conditions and boundary conditions to perform static simulation, and obtain the simulated values ​​of the peak pressure of the foot sole, the peak pressure of the shoe sole, and the total deformation of a specific area.

[0112] In this step, initial and boundary conditions are set according to the actual force conditions of each posture, including:

[0113] A vertically upward ground reaction force is applied to the bottom of the floor. The magnitude of this ground reaction force is set to half the subject's body weight; (e.g., if the subject weighs 70kg, the ground reaction force is 70 / 2*9.8=343N). This value is based on the fact that all three postures involve bipedal support, with the weight borne by both feet. Therefore, the ground reaction force borne by a single foot is less than the body weight, approximately 50%-70%. The median value of 50% is used as a uniform standard to maintain consistency in the mechanical boundary conditions for the three postures. Figure 4 As shown;

[0114] The frictional contact between the foot and the shoe upper, and between the shoe sole and the ground, is set with a friction coefficient of 0.6. This value is based on relevant reports on the frictional characteristics between typical shoe materials (such as insole fabric and rubber outsole) and human skin and floor, while also taking into account the stability requirements of contact convergence in finite element simulation.

[0115] During static simulation, the peak plantar pressure values ​​for the foot regions T1, T2, 3, 4, 5, M1, M2, M3, M4, M5, MF, MH, and LH, and the peak sole pressure values ​​for the shoe regions T1, T2, 3, 4, 5, M1, M2, M3, M4, M5, MF, MH, and LH, were obtained under three postures: toe-landing posture, static standing posture, and heel-landing posture. The total deformation simulation values ​​for the shoe sole region M3 under toe-landing posture, the shoe sole region MF under static standing posture, and the shoe sole region MH under heel-landing posture were also obtained. The distribution of each region on the foot and shoe sole is shown below. Figure 5As shown.

[0116] S5. Physical tests were conducted on the subjects wearing footwear in the same posture to obtain the measured peak value of plantar pressure, the measured peak value of shoe sole pressure, and the measured value of total deformation in a specific area.

[0117] In this step, when the subjects are wearing shoes and undergoing physical testing in the same posture, the peak values ​​of the measured plantar pressure in the foot regions T1, T2, 3, 4, 5, M1, M2, M3, M4, M5, MF, MH, and LH, and the peak values ​​of the measured shoe sole pressure in the shoe sole regions T1, T2, 3, 4, 5, M1, M2, M3, M4, M5, MF, MH, and LH are measured using a pressure plate and a patch-type plantar pressure sensor. At the same time, the total deformation of the shoe sole region M3 when the toes touch the ground, the shoe sole region MF when standing statically, and the shoe sole region MH when the heel touches the ground are measured using CT scanning or 3D scanning technology.

[0118] S6. By combining the simulated and measured values ​​of the peak pressure of the foot and the peak pressure of the shoe sole, as well as the total deformation in a specific area, error analysis is performed. Based on the principle of minimizing the total error, the optimal combination of ligament elastic modulus and Poisson's ratio parameters is selected to construct a standard foot-shoe three-dimensional numerical model.

[0119] In this step, such as Figure 6 As shown, error analysis is performed by combining the simulated and measured values ​​of peak foot pressure, peak shoe sole pressure, and total deformation in a specific area. The process for calculating the total error is as follows:

[0120] Calculate the average error of peak plantar pressure in toe-landing, static standing, and heel-landing postures respectively. , , The formula for obtaining the answer is as follows:

[0121] ;

[0122] in, This indicates the area number, corresponding to areas T1, T2, 3, 4, 5, M1, M2, M3, M4, M5, MF, MH, and LH, respectively. This indicates the average error of the peak plantar pressure under the corresponding posture (corresponding to , , ), Indicates the first position under the corresponding attitude Simulated plantar pressure values ​​for the region Indicates the first position under the corresponding attitude Measured plantar pressure values ​​for the region;

[0123] Calculate the average error of the peak sole pressure under the toe-landing posture, static standing posture, and heel-landing posture respectively. , , The formula for obtaining the answer is as follows:

[0124] ;

[0125] This indicates the average error of the peak pressure of the sole under the corresponding posture (corresponding to...). , , ), Indicates the first position under the corresponding attitude Simulated values ​​of sole pressure in the region Indicates the first position under the corresponding attitude Measured values ​​of sole pressure in the area;

[0126] Calculate the percentage difference between the simulated and measured values ​​of the total deformation of the sole region M3 in the toe-landing posture, the sole region MF in the static standing posture, and the sole region MH in the heel-landing posture, respectively, relative to the measured values; this is the corresponding relative error. , , The formula for obtaining the answer is as follows:

[0127] ;

[0128] This represents the relative error in the corresponding region of the corresponding attitude (corresponding to) , , ), This represents the simulated value of the corresponding total deformation. This represents the measured value of the corresponding total deformation.

[0129] Calculate the total average error of the peak plantar pressure :

[0130] ;

[0131] Calculate the total average error of the peak pressure of the sole. :

[0132] ;

[0133] Calculate the total relative error of the total deformation in the sole area. :

[0134] ;

[0135] Calculate the total error:

[0136] .

[0137] Compare the total error of 9 parameter combinations , choose to The minimum parameter combination is used as the optimal ligament material parameters to construct a standard foot-shoe three-dimensional numerical model.

[0138] In addition, this embodiment also includes a novel foot-shoe three-dimensional numerical model construction system for implementing the aforementioned novel foot-shoe three-dimensional numerical model construction method, such as... Figure 7 As shown, it includes:

[0139] The multi-posture data acquisition module is used to acquire scan data of the subject's feet and footwear in three postures: toe-on, static standing, and heel-on, using a CT scanning device.

[0140] The three-dimensional geometric modeling module is used to construct three-dimensional geometric models of the foot and shoe in the corresponding poses based on the scanned image data, and to perform mesh generation and material property assignment to establish a three-dimensional finite element numerical model of the foot and shoe.

[0141] The 3D finite element numerical modeling module is used to mesh and assign material properties to the constructed 3D geometric model, and to establish a 3D finite element numerical model of a foot-shoe.

[0142] The statics simulation module inputs the ligament elastic modulus and Poisson's ratio parameters into the three-dimensional finite element numerical model of the foot-shoe, and sets the initial conditions and boundary conditions to perform statics simulation, and obtains the simulated values ​​of the peak pressure of the foot sole, the peak pressure of the shoe sole, and the total deformation of a specific area.

[0143] The physical testing module is used to conduct physical tests on subjects wearing footwear in the same posture to obtain the measured peak value of plantar pressure, the measured peak value of shoe sole pressure, and the measured value of total deformation in a specific area.

[0144] The error analysis module is used to perform error analysis by combining the simulated and measured values ​​of the peak foot pressure, peak shoe pressure, and total deformation in a specific area to obtain the total error.

[0145] The parameter selection and model building module is used to select the combination of ligament elastic modulus and Poisson's ratio parameters that minimizes the total error, and to build a standard foot-shoe three-dimensional numerical model based on the optimal ligament parameters.

[0146] The above-described embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Therefore, any changes made in accordance with the shape and principle of the present invention should be covered within the protection scope of the present invention.

Claims

1. A novel method for constructing a three-dimensional numerical model of a foot-shoe, characterized in that, include: Using a spiral CT scanner, scan data of the subject's feet and footwear were collected in three postures: toe-toe, static standing, and heel-to-toe. Based on the acquired scan data, three-dimensional geometric models of the foot and shoe are constructed for the toe-landing posture, static standing posture, and heel-landing posture, respectively; the three-dimensional geometric models of the foot and shoe include foot bones, soft tissues, ligaments, and shoe components; The constructed three-dimensional geometric model was meshed and material properties were assigned to establish a three-dimensional finite element numerical model of foot-shoe; among which, the elastic modulus and Poisson's ratio of the ligament were used as parameters to be optimized. Input the ligament elastic modulus and Poisson's ratio parameters into the three-dimensional finite element numerical model of foot-shoe, and set the initial conditions and boundary conditions to perform static simulation, and obtain the simulated values ​​of the peak pressure of the foot sole, the peak pressure of the shoe sole, and the total deformation of a specific area; Physical tests were conducted on subjects wearing footwear in the same posture to obtain the measured peak value of plantar pressure, the measured peak value of shoe sole pressure, and the measured value of total deformation in a specific area. Error analysis was conducted by combining the simulated and measured values ​​of peak plantar pressure, peak shoe pressure, and total deformation in a specific area. Based on the principle of minimizing total error, the optimal combination of ligament elastic modulus and Poisson's ratio parameters was selected to construct a standard foot-shoe three-dimensional numerical model.

2. The method according to claim 1, wherein, Initial and boundary conditions are set according to the actual force conditions of each posture, including: Restraining the upper surface of the foot bones and the upper surface of the foot soft tissues; A vertically upward ground reaction force is applied to the bottom of the floor, and the magnitude of the ground reaction force is set to half the subject's body weight; The foot bones and soft tissues are bound together; the insole, upper, midsole and outsole are bound together; and the attachment points of the foot bones and ligaments are coupled together. The frictional contact between the foot and the upper of the shoe, the sole of the foot and the insole, and the sole of the shoe and the ground are set, with the coefficient of friction set to 0.

6.

3. The method according to claim 1, wherein, During static simulation, the peak plantar pressure values ​​of the foot regions T1, T2, 3, 4, 5, M1, M2, M3, M4, M5, MF, MH, and LH, the peak shoe sole pressure values ​​of the shoe sole regions T1, T2, 3, 4, 5, M1, M2, M3, M4, M5, MF, MH, and LH, and the total deformation simulation values ​​of the shoe sole region M3 in the toe-landing posture, the shoe sole region MF in the static standing posture, and the shoe sole region MH in the heel-landing posture are obtained respectively.

4. The novel foot-shoe three-dimensional numerical model construction method according to claim 3, characterized in that, When subjects were wearing footwear and undergoing physical testing in the same posture, the peak values ​​of the measured plantar pressure in the foot regions T1, T2, 3, 4, 5, M1, M2, M3, M4, M5, MF, MH, and LH, and the peak values ​​of the measured shoe sole pressure in the same posture were measured using a pressure plate and patch-type plantar pressure sensors. Simultaneously, the total deformation of the shoe sole region M3 when the toes touched the ground, the shoe sole region MF when standing statically, and the shoe sole region MH when the heel touched the ground was measured using CT scanning or three-dimensional scanning technology.

5. The novel foot-shoe three-dimensional numerical model construction method according to claim 4, characterized in that, Error analysis was performed by combining simulated and measured values ​​of peak plantar pressure, peak shoe sole pressure, and total deformation in a specific area. The process for calculating the total error is as follows: Calculate the average error of peak plantar pressure in toe-landing, static standing, and heel-landing postures respectively. , , The formula for obtaining the result is as follows: ； in, Indicates the area code; This represents the average error of the peak plantar pressure under the corresponding posture. Indicates the first position under the corresponding attitude Simulated plantar pressure values ​​for the region Indicates the first position under the corresponding attitude Measured plantar pressure values ​​for the area; Calculate the average error of the peak sole pressure under the toe-landing posture, static standing posture, and heel-landing posture respectively. , , The formula for obtaining the result is as follows: ； This represents the average error of the peak pressure of the sole under the corresponding posture. Indicates the first position under the corresponding attitude Simulated values ​​of sole pressure in the region Indicates the first position under the corresponding attitude Measured values ​​of sole pressure in the region; Calculate the percentage difference between the simulated and measured values ​​of the total deformation of the sole region M3 in the toe-landing posture, the sole region MF in the static standing posture, and the sole region MH in the heel-landing posture, respectively, relative to the measured values; this is the corresponding relative error. , , The formula for obtaining the result is as follows: ； This represents the relative error within the corresponding region of the corresponding attitude. This represents the simulated value of the corresponding total deformation. This represents the measured value of the corresponding total deformation. Calculate the total average error of the peak plantar pressure : ； Calculate the total average error of the peak pressure of the sole. : ； Calculate the total relative error of the total deformation in the sole area. : ； Calculate the total error: 。 6. The novel foot-shoe three-dimensional numerical model construction method according to claim 1, characterized in that, When collecting scanning data of the subject's feet and shoes while the subject is wearing shoes and in a toe-landing state, the angle between the subject's sole and the ground is controlled at 20°. When collecting scan data of the subject's feet and shoes while the heel was on the ground, the angle between the sole of the foot and the ground was controlled to be -10°.

7. A novel method for constructing a three-dimensional numerical model of a foot-shoe according to claim 1, characterized in that, The combination of ligament elastic modulus and Poisson's ratio parameters was selected within a physiologically reasonable range. The ligament elastic modulus was based on 260 MPa and varied by ±10%. The Poisson's ratio was selected within the range of 0.4 to 0.

495. Nine sets of parameter combinations were formed by pairwise combinations and then tested.

8. The novel foot-shoe three-dimensional numerical model construction method according to claim 1, characterized in that, The ligaments include the metatarsophalangeal joint collateral ligament between the metatarsals and phalanges, the interphalangeal joint collateral ligament between the phalanges, and the talocalcaneal interphalangeal ligament between the talus and calcaneus.

9. A novel foot-shoe three-dimensional numerical model construction system, used to implement the novel foot-shoe three-dimensional numerical model construction method according to any one of claims 1-8, characterized in that, include: The multi-posture data acquisition module is used to acquire scan data of the subject's feet and footwear in three postures: toe-on, static standing, and heel-on, using a CT scanning device. The three-dimensional geometric modeling module is used to construct three-dimensional geometric models of the foot and shoe in the corresponding poses based on the scanned image data, and to perform mesh generation and material property assignment to establish a three-dimensional finite element numerical model of the foot and shoe. The 3D finite element numerical modeling module is used to mesh and assign material properties to the constructed 3D geometric model, and to establish a 3D finite element numerical model of a foot-shoe. The static simulation module inputs the ligament elastic modulus and Poisson's ratio parameters into the three-dimensional finite element numerical model of the foot-shoe, and sets the initial conditions and boundary conditions to perform static simulation, and obtains the simulated values ​​of the peak pressure of the foot sole, the peak pressure of the shoe sole, and the total deformation of a specific area. The physical testing module is used to conduct physical tests on subjects wearing footwear in the same posture to obtain the measured peak value of plantar pressure, the measured peak value of shoe sole pressure, and the measured value of total deformation in a specific area. The error analysis module is used to perform error analysis by combining the simulated and measured values ​​of the peak foot pressure, peak shoe pressure, and total deformation in a specific area to obtain the total error. The parameter selection and model building module is used to select the combination of ligament elastic modulus and Poisson's ratio parameters that minimizes the total error, and to build a standard foot-shoe three-dimensional numerical model based on the optimal ligament parameters.

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