Method for foot adaptive support adjustment based on biomechanical model

Abstract

The present application relates to the technical field of footwear, and discloses a foot adaptive support adjustment method based on a biomechanical model, comprising the following steps: S1: foot biomechanical modeling: acquiring user foot geometry data through three-dimensional scanning, combining with gait analysis to collect dynamic load parameters, and constructing a personalized foot finite element model; S2: stress distribution calculation: sampling at 10% intervals from 0% to 100% in the gait cycle; S3: material gradient design: determining the gradient material stiffness mapping relationship according to P max distribution; S4: adaptive structure implementation: constructing a gradient sole structure through 3D printing. The high shear force area is determined by double threshold values, and a pressure gradient adaptive non-uniform honeycomb structure and configuration grading are arranged in the area, so that local deformation is dynamically controlled during the extension period and the landing period, and the effects of reducing the stress peak value of the high shear area and reducing the accumulation of friction heat are achieved.

Description

Technical Field

[0001] This invention relates to the field of footwear technology, specifically to a foot adaptive support adjustment method based on a biomechanical model. Background Technology

[0002] Footwear technology refers to the various technologies and materials applied to footwear products, aiming to improve the functionality, comfort, and sustainability of footwear. It encompasses multiple aspects, including the research and development of midsole materials such as PU foam, PHYLON, and EVA, as well as the application of high-end materials such as carbon fiber; the design of special components to enhance foot support and stability; shoe manufacturing processes are also an important part of footwear technology, including injection molding, vulcanization, gluing, machine-made Goodyear welt construction, and handmade Goodyear welt construction, each with its own characteristics and applicable scope; in addition, smart shoe technology uses sensors and networks to achieve functions such as fitness tracking and health monitoring.

[0003] Related footwear technologies typically employ homogenized cushioning materials or simple zoned structures to achieve shock absorption, but these are difficult to dynamically adapt to the rapidly changing shear stress field during the gait cycle. In particular, during the transition from heel strike to push-off, localized high-shear areas often appear at the sole-shoe interface. The shear stress values ​​in these areas not only exceed the physiological tolerance threshold, but their continuous action will also lead to the accumulation of frictional heat. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a foot adaptive support adjustment method based on a biomechanical model, which solves the problem of frictional heat accumulation caused by the use of homogenized cushioning materials or simple partitioned structures in related footwear technologies.

[0005] To achieve the above objectives, this invention provides the following technical solution: a foot adaptive support adjustment method based on a biomechanical model, comprising the following modules: a foot biomechanical modeling module, a stress distribution calculation module, and a material topology optimization module; the method includes the following steps:

[0006] S1: Foot Biomechanical Modeling: Geometric data of the user's foot is acquired through 3D scanning, and dynamic load parameters are collected by gait analysis to construct a personalized foot finite element model. The model satisfies the following: , where σ is the structural stress, E is the elastic modulus, ε is the strain, and η is the viscosity coefficient;

[0007] S2: Stress distribution calculation: During the gait cycle, samples are taken at 10% phase intervals from 0% to 100% to calculate the peak pressure point P at the foot-shoe contact interface. max and high shear force region S area ;

[0008] S3: Material gradient design: based on Pmax The distribution determines the gradient material stiffness mapping relationship: E(x,y)=k·ln(P(x,y)+1)+E0, where x,y are the foot coordinates, k is the adjustment coefficient, and E0 is the base modulus;

[0009] S4: Adaptive Structure Implementation: A gradient sole structure is constructed using 3D printing, which includes:

[0010] Layered material zones: The forefoot area uses a positive gradient material, with hardness increasing by 5% to 15% from the surface to the inner layer; the arch area uses a negative gradient material, with hardness decreasing by 8% to 12% from the surface to the inner layer.

[0011] Microstructural units: in S area The region is configured with a non-uniform honeycomb structure, and the unit wall thickness t satisfies: t = t max -α·|▽P|, where ▽P is the pressure gradient and α is the deformation factor;

[0012] Dynamic response chamber: A semi-enclosed air chamber is set below the calcaneus. The relationship between the air chamber volume V and the load F is: V = V0·e (-β·F) Where V0 is the reference volume of the dynamic response chamber in the initial unpressurized state, β is the gas compression response coefficient, which is fixed at 0.03 mm² / N, and F is the vertical load acting on the top of the gas chamber.

[0013] By employing the above technical solution, a finite element model is constructed. Simultaneously, the stress distribution calculation module performs discrete sampling at 10% phase intervals during the gait cycle to calculate the pressure distribution at the foot-shoe interface and extract peak pressure points and high shear stress regions. A stiffness mapping function is established by the material topology optimization module; this logarithmic function achieves load dispersion through nonlinear stiffness growth in high-pressure areas. Finally, a gradient sole structure is manufactured using multi-material 3D printing, including: a positive gradient in the forefoot layered material area to enhance push-off energy feedback, and a negative gradient in the arch to improve support and compliance; microstructural units generate non-uniform honeycombs with varying wall thickness as pressure gradients in high-shear stress regions to control shear stress; and a dynamic response cavity is set below the calcaneus, based on the formula V=V0·e (-β·F) Compression enables adaptive dissipation of impact energy.

[0014] Preferably, the finite element model in step S1 includes the following anatomical structural regions: calcaneal region, lateral arch region, medial arch region, first metatarsal region, second-third metatarsal region, fourth-fifth metatarsal region, and phalangeal region.

[0015] Preferably, the high shear force region in step S2 is a region where the shear force is greater than 1.5 times the average value and lasts for more than 15% of the gait cycle.

[0016] Preferably, the method for determining the adjustment coefficient k in step S3 is: k = 0.01·BMI + 0.7, where BMI is the user's body fat index.

[0017] Preferably, the honeycomb configuration of the microstructure unit is as follows: hexagonal honeycomb is used in the region where the pressure gradient |▽P|≥0.3MPa / cm, quadrilateral honeycomb is used in the region where 0.1MPa / cm≤|▽P|<0.3MPa / cm, and triangular honeycomb is used in the region where |▽P|<0.1MPa / cm.

[0018] Preferably, the wall thickness distribution of the dynamic response cavity satisfies: the outer wall thickness δ1 = 1.2δ2, where δ2 is the inner wall thickness, and a silicone damping membrane is provided at the top of the cavity.

[0019] Preferably, a biomimetic tendon structure is provided in the arch support area, and a unidirectional stretching fiber bundle is embedded in the elastic matrix. The angle γ of the fiber bundle is inversely proportional to the height H of the arch: γ = 40° - 0.8H.

[0020] Preferably, the value of E0 in step S3 is dynamically adjusted based on the arch type: E0 = 3.5 ± 0.3 MPa for flat feet, E0 = 2.8 ± 0.2 MPa for normal arches, and E0 = 2.0 ± 0.2 MPa for high arches.

[0021] Preferably, the Shore hardness H of the silicone damping membrane satisfies the following condition with respect to the user's weight W: H = 0.25W + 40, and the thickness is 0.5 ± 0.1 mm.

[0022] Preferably, a flexible hinge structure is provided in the toe bone area, with a bending stiffness K. b K is negatively correlated with the toe joint flexion angle θ: b =12-0.1θ.

[0023] This invention provides a foot adaptive support adjustment method based on a biomechanical model. It has the following beneficial effects:

[0024] 1. This invention determines high shear force regions by using dual thresholds and deploys non-uniform honeycomb structures and configuration gradations with pressure gradient adaptation in these regions. This allows for dynamic control of local deformation during the push-off and landing phases, thereby reducing the peak stress in high shear regions and minimizing frictional heat accumulation.

[0025] 2. This invention determines the stiffness of shoe materials by coordinating the adjustment coefficient k associated with the user's BMI and the base modulus E0 dynamically adjusted according to the arch type, thereby matching the material stiffness distribution with individual load characteristics and achieving the effect of optimizing the non-uniformity index of the entire sole pressure.

[0026] 3. This invention constructs a finite element model that includes the calcaneal region, the medial and lateral arch regions, the metatarsal regions, and the phalangeal regions, and sets the boundary conditions and elastic coupling mechanism of the regions. This allows for the simulation of the dynamic mechanical response of each anatomical structure during the gait cycle, providing a high-fidelity biomechanical basis for stress distribution calculation and material gradient design, and supporting the reduction of positioning errors.

[0027] 4. The fiber angle adjustment of the bionic tendon in the arch area and the variable stiffness design of the flexible hinge in the phalanx area of ​​this invention, respectively, work in conjunction with the negative gradient hardness and positive gradient hardness of the layered material area, thereby enhancing the arch's anti-collapse ability in the mid-gait support phase and reducing the bending resistance of the toe joints in the push-off phase, thus achieving the effect of reducing kinetic energy loss in the gait cycle. Attached Figure Description

[0028] Figure 1 This is a flowchart of the foot adaptive support adjustment method based on a biomechanical model proposed in this invention. Detailed Implementation

[0029] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. 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 are within the scope of protection of the present invention.

[0030] Please see the appendix Figure 1 This invention provides a foot adaptive support adjustment method based on a biomechanical model, comprising the following modules: a foot biomechanical modeling module, a stress distribution calculation module, and a material topology optimization module; the method includes the following steps:

[0031] S1: Foot Biomechanical Modeling: Geometric data of the user's foot is acquired through 3D scanning, and dynamic load parameters are collected by gait analysis to construct a personalized foot finite element model. The model satisfies the following: , where σ is the structural stress, E is the elastic modulus, ε is the strain, and η is the viscosity coefficient;

[0032] S2: Stress distribution calculation: During the gait cycle, samples are taken at 10% phase intervals from 0% to 100% to calculate the peak pressure point P at the foot-shoe contact interface. max and high shear force region S area ;

[0033] S3: Material gradient design: based on P max The distribution determines the gradient material stiffness mapping relationship: E(x,y)=k·ln(P(x,y)+1)+E0, where x,y are the foot coordinates, k is the adjustment coefficient, and E0 is the base modulus;

[0034] S4: Adaptive Structure Implementation: A gradient sole structure is constructed using 3D printing, which includes:

[0035] Layered material zones: The forefoot area uses a positive gradient material, with hardness increasing by 5% to 15% from the surface to the inner layer; the arch area uses a negative gradient material, with hardness decreasing by 8% to 12% from the surface to the inner layer.

[0036] Microstructural units: in S area The region is configured with a non-uniform honeycomb structure, and the unit wall thickness t satisfies: t = t max -α·|▽P|, where ▽P is the pressure gradient and α is the deformation factor;

[0037] Dynamic response chamber: A semi-enclosed air chamber is set below the calcaneus. The relationship between the air chamber volume V and the load F is: V=V0·e(-β·F), where V0 is the reference volume of the dynamic response chamber in the initial unpressurized state, β is the gas compression response coefficient, which is fixed at 0.03mm² / N, and F is the vertical load acting on the top of the air chamber.

[0038] Specifically, the system first obtains the precise geometric contour of the user's foot through a foot biomechanical modeling module, while simultaneously collecting dynamic load time-series data during walking using a gait analysis device. Based on these two types of data, the module constructs a personalized foot finite element model incorporating viscoelastic properties. The stress distribution calculation module then discretizes the sampling at 10% phase intervals during the gait cycle, calculating the pressure distribution at the foot-shoe contact interface in each phase and extracting the peak pressure point P. max and high shear force region S area Meanwhile, the material topology optimization module optimizes based on P. max A spatial mapping relationship for material stiffness is established: E(x,y)=k·ln(P(x,y)+1)+E0, where (x,y) are the plantar coordinates, k is the adjustment coefficient related to body weight, and E0 is the base modulus related to arch type. This logarithmic function form ensures nonlinear growth of material stiffness in high-pressure areas to distribute the load. Finally, a gradient sole structure is achieved through multi-material 3D printing technology: in the layered material area, a positive gradient design is adopted in the forefoot to enhance energy feedback during push-off, and a negative gradient design is adopted in the arch to improve support compliance; in the microstructural unit area, a gradient design is adopted for the high shear force area S area A non-uniform honeycomb structure with wall thickness varying with pressure gradient is generated, and shear stress is controlled by local deformation. In the dynamic response cavity design, the semi-enclosed air chamber below the calcaneus is compressed exponentially according to the load F to achieve adaptive dissipation of impact energy.

[0039] The finite element model in step S1 includes the following anatomical structural regions: calcaneal region, lateral arch region, medial arch region, first metatarsal region, second-third metatarsal region, fourth-fifth metatarsal region, and phalangeal region.

[0040] Specifically, the model divides the sole of the foot into seven zones based on the biomechanical function of the foot. The calcaneal zone, as the weight-bearing area at the posterior end of the foot, is captured by the model in terms of its geometric shape and bony structure. The lateral and medial arch zones correspond to the supporting surfaces of the lateral and medial longitudinal arches, respectively. The model simulates the dynamic deformation behavior of the arch during gait by distinguishing the morphological differences between the two zones. In the forefoot region, the model divides the metatarsals into three zones: the first metatarsal zone is modeled independently to reflect the biomechanical characteristics when the big toe bears weight; the second and third metatarsal zones are combined as a whole to simulate the synergistic load transfer mechanism during the midfoot transition; and the fourth and fifth metatarsal zones jointly characterize the stress distribution pattern of the lateral arch during the push-off phase. The distal phalangeal zone covers all phalanges and metatarsophalangeal joints, and the model describes the stress transmission path during flexion.

[0041] The above partition structure is applied in S2: the partition boundary conditions are set as physiological motion constraints of each anatomical structure, and the mechanical coupling between partitions is achieved through elastic connection, so that the contact pressure P and shear force τ of each region can be calculated independently in each phase of the gait cycle, and a spatial positioning benchmark is provided for the material gradient design in S3, thereby forming a modeling framework that aligns anatomical structure with functional requirements.

[0042] The high shear force region in step S2 is the region where the shear force is greater than 1.5 times the average value and lasts for more than 15% of the gait cycle.

[0043] Specifically, in S2, the criteria for determining the high shear force region are achieved through a dual mechanical and time threshold:

[0044] Mechanical threshold: Based on the calculation results of the finite element model at each phase of the gait cycle, the arithmetic mean τ of the shear force at the full plantar contact interface is first calculated. - ;

[0045] Time threshold: Identifies when the shear force continuously exceeds a critical value of 1.5τ. - The region must be in an over-limit state, and this over-limit state must be maintained for at least three consecutive sampling phases;

[0046] Applying this judgment criterion to S4, the determined S area The region will serve as the location for the deployment of the cellular structure, and its duration must ensure that the deformation response of the cellular structure is synchronized with the shear force accumulation phase during gait.

[0047] The method for determining the adjustment coefficient k in step S3 is: k = 0.01·BMI + 0.7, where BMI is the user's body fat index.

[0048] Specifically, in S3, the user's BMI value is input into the material topology optimization module, and then k is obtained according to the formula k=0.01·BMI+0.7. In the formula, the linear term coefficient of 0.01 ensures the material stiffness's sensitive response to load differences, while the constant term of 0.7 is used to maintain the stiffness of the foundation support. k transforms the stress distribution calculation results into parameters of the stiffness mapping function E(x,y)=k·ln(P(x,y)+1)+E0, which in turn affects the hardness gradient design of the 3D printed layered material area in S4. That is, for users with higher BMI, the k value increases, and their shoe sole material stiffness curve is steeper to match higher load requirements.

[0049] The honeycomb configuration of the microstructure unit is as follows: hexagonal honeycomb is used in the region where the pressure gradient |▽P|≥0.3MPa / cm, quadrilateral honeycomb is used in the region where 0.1MPa / cm≤|▽P|<0.3MPa / cm, and triangular honeycomb is used in the region where |▽P|<0.1MPa / cm.

[0050] Specifically, the selection of the honeycomb configuration is strictly based on spatial zoning control according to the pressure gradient amplitude:

[0051] High-pressure gradient zone: It adopts a hexagonal honeycomb structure, and its isotropic high stiffness characteristics can resist the drastic pressure changes during the heel impact period or the end of the push-off.

[0052] Medium pressure gradient zone: A quadrilateral honeycomb structure is selected, which adapts to the shear-compression composite load of the foot arch transition zone through orthogonal anisotropic deformation capability;

[0053] Low-pressure gradient region: Deploy a triangular honeycomb configuration to maintain the flexible bending requirements of the phalanx region with a low-density, lightweight structure.

[0054] The wall thickness distribution of the dynamic response cavity satisfies the following: outer wall thickness δ1 = 1.2δ2, where δ2 is the inner wall thickness, and a silicone damping membrane is provided at the top of the cavity.

[0055] Specifically, the distribution of air chamber wall thickness and damping settings are differentiated based on the biomechanical characteristics of the calcaneal region: the outer wall thickness δ1 of the air chamber is set to 1.2 times the inner wall thickness δ2. By thickening the outer wall, the eversion torque during heel strike can be resisted. At the same time, a silicone damping membrane is set at the heel contact interface at the top of the air chamber. This damping membrane converts the kinetic energy generated during the gas compression process into heat energy, which synergistically inhibits the lateral expansion of the air chamber and resonates with the air pressure, thereby reducing the pressure on the arch of the foot.

[0056] A biomimetic tendon structure is set in the arch support area, and a unidirectional stretching fiber bundle is embedded in the elastic matrix. The angle γ of the fiber bundle is inversely proportional to the height H of the arch: γ = 40° - 0.8H.

[0057] Specifically, in the arch support area, high-strength unidirectional fiber bundles are embedded in the elastic matrix material at a specific angle γ. This angle is dynamically set to γ=40°-0.8H based on the arch height H calculated by the finite element model. According to this formula, the lower arch γ is increased to enhance the anti-collapse ability, while the higher arch γ is decreased to avoid excessive lifting. At the same time, it complements the negative gradient hardness design of the layered material area. That is, the fiber bundles provide directional tensile stiffness, and the elastic matrix ensures multi-directional deformation, which together reduce the shear force in the medial arch area.

[0058] In step S3, the value of E0 is dynamically adjusted based on the arch type: for flat feet, E0 = 3.5 ± 0.3 MPa; for normal arches, E0 = 2.8 ± 0.2 MPa; and for high arches, E0 = 2.0 ± 0.2 MPa.

[0059] Specifically, in S3, the value of the base modulus E0 is dynamically adjusted according to the arch type output by S1: the arch type is determined based on the geometric characteristics and load distribution pattern of the inner and outer arch zones in S1. For flat feet, E0 is set to 3.5±0.3MPa to enhance the anti-collapse stiffness. For normal arches, E0 is set to 2.8±0.2MPa to balance support and cushioning. For high arches, E0 is set to 2.0±0.2MPa to reduce the risk of pressure concentration.

[0060] The Shore hardness H of the silicone damping membrane satisfies the following condition with respect to the user's weight W: H = 0.25W + 40, and the thickness is 0.5 ± 0.1 mm.

[0061] Specifically, the Shore hardness H is bound to the user's physiological characteristics through the formula H=0.25W+40. The coefficient 0.25 comes from the kinetic energy absorption model that requires an increase of 0.25A hardness for every 1kg increase in weight to maintain a constant deformation rate. The constant term 40 ensures the buffer threshold under a base weight of 60kg. The thickness is simultaneously limited to 0.5±0.1mm to balance damping rate and durability.

[0062] A flexible hinge structure is set in the toe bone area, and its bending stiffness Kb is negatively correlated with the toe joint flexion angle θ: Kb=12-0.1θ.

[0063] Specifically, the material topology optimization module automatically calculates the Kb value based on the gait phase data of S2, and converts it into the material density distribution of the hinge area through 3D printing. This allows it to work synergistically with the positive gradient design of the layered material area in the phalangeal region. As the buckling angle increases, the stiffness decreases, reducing bending resistance. Simultaneously, the positive gradient material provides longitudinal support, jointly improving the efficiency of propulsion force transmission.

[0064] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A foot adaptive support adjustment method based on a biomechanical model, characterized in that, The method includes the following modules: foot biomechanical modeling module, stress distribution calculation module, and material topology optimization module; the method comprises the following steps: S1: Foot Biomechanical Modeling: Geometric data of the user's foot is acquired through 3D scanning, and dynamic load parameters are collected by gait analysis to construct a personalized foot finite element model. The model satisfies the following: Where σ is the structural stress, E is the elastic modulus, ε is the strain, η is the viscosity coefficient, and dε / dt represents the strain rate, that is, the rate of change of strain ε with time t. S2: Stress distribution calculation: During the gait cycle, samples are taken at 10% intervals from 0% to 100% of the phase. The pressure distribution at the foot-shoe contact interface is calculated for each phase, and the peak pressure point P at the foot-shoe contact interface is extracted. max and high shear force region S area The high shear force region S area The region is defined as one in which the shear force is greater than 1.5 times the average value and persists for more than 15% of the gait cycle. S3: Material gradient design: based on P max The distribution determines the gradient material stiffness mapping relationship: E(x,y)=k·ln(P(x,y)+1)+E0, where P(x,y) represents the pressure at the foot-shoe contact interface at specified coordinates in two-dimensional space, (x,y) is the foot coordinate, k is the adjustment coefficient related to body weight, and E0 is the base modulus related to the arch type. S4: Adaptive Structure Implementation: A gradient sole structure is constructed using 3D printing, which includes: Layered material zones: The forefoot area uses a positive gradient material, with hardness increasing by 5% to 15% from the surface to the inner layer; the arch area uses a negative gradient material, with hardness decreasing by 8% to 12% from the surface to the inner layer. Microstructural unit: in the high shear force region S area A non-uniform honeycomb structure is configured such that the element wall thickness t satisfies: t=t max -α·|▽P|, where ▽P is the pressure gradient and α is the deformation factor; Dynamic response chamber: A semi-enclosed air chamber is set below the calcaneus. The relationship between the air chamber volume V and the load F is: V = V0·e (-β·F) Where V0 is the reference volume of the dynamic response chamber in the initial unpressurized state, β is the gas compression response coefficient, which is fixed at 0.03 mm² / N, and F is the vertical load acting on the top of the gas chamber.

2. The foot adaptive support adjustment method based on a biomechanical model according to claim 1, characterized in that, The finite element model in step S1 includes the following anatomical structural regions: calcaneal region, lateral arch region, medial arch region, first metatarsal region, second-third metatarsal region, fourth-fifth metatarsal region, and phalangeal region.

3. The foot adaptive support adjustment method based on a biomechanical model according to claim 1, characterized in that, The honeycomb configuration of the microstructure unit is as follows: hexagonal honeycomb is used in the region where |▽P|≥0.3MPa / cm, quadrilateral honeycomb is used in the region where 0.1MPa / cm≤|▽P|<0.3MPa / cm, and triangular honeycomb is used in the region where |▽P|<0.1MPa / cm.

4. The foot adaptive support adjustment method based on a biomechanical model according to claim 1, characterized in that, The wall thickness distribution of the dynamic response cavity satisfies the following: outer wall thickness δ1 = 1.2δ2, where δ2 is the inner wall thickness, and a silicone damping membrane is provided at the top of the cavity.

5. The foot adaptive support adjustment method based on a biomechanical model according to claim 1, characterized in that, In step S3, the value of E0 is dynamically adjusted based on the arch type: for flat feet, E0 = 3.5 ± 0.3 MPa; for normal arches, E0 = 2.8 ± 0.2 MPa; and for high arches, E0 = 2.0 ± 0.2 MPa.

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