Foot self-adaptive support adjusting method based on biomechanical model

Abstract

The invention relates to the technical field of shoes, and discloses a foot self-adaptive support adjusting method based on a biomechanical model, which comprises the following steps: S1, foot biomechanical modeling: acquiring foot geometric data of a user through three-dimensional scanning, acquiring dynamic load parameters in combination with gait analysis, and constructing a personalized foot finite element model; s2, stress distribution calculation: sampling according to 0-100% phase intervals of 10% in a gait cycle; s3, material gradient design: determining a gradient material rigidity mapping relation according to Pmax distribution; and S4, realizing a self-adaptive structure: constructing a gradient sole structure through 3D printing. A high-shear-force area is judged through double threshold values, and a pressure gradient self-adaptive non-uniform honeycomb structure and configuration classification are arranged in the area, so that local deformation is dynamically regulated and controlled in a pedaling and stretching period and a landing period, and the effects of reducing a stress peak value of the high-shear area and reducing friction heat accumulation are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of footwear, and in particular to a foot adaptive support adjustment method based on a biomechanical model. Background Art

[0002] Footwear technology refers to the various technologies and materials applied to footwear products, aiming to enhance the functionality, comfort and sustainability of footwear. It covers multiple aspects, including the research and development of midsole materials such as PU foam, PHYLON, EVA, etc., as well as the application of high-end materials such as carbon fiber. There is also the design of special components to enhance support and stability for the foot. Shoemaking technology is also an important part of footwear technology, including injection molding, vulcanization, gluing, motorcycle Goodyear and hand Goodyear, each with its own characteristics and scope of application. In addition, smart shoe technology uses sensors and networks to achieve fitness tracking, health monitoring and other functions.

[0003] Related footwear technologies usually use homogenized cushioning materials or simple partitioned structures to achieve shock absorption and cushioning effects, which makes it difficult to dynamically adapt to the rapidly changing shear stress field during the gait cycle; especially in the transition phase from heel strike to extension, 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 continued action time will also lead to frictional heat accumulation. Summary of the Invention

[0004] In response to the shortcomings of the existing technology, the present invention provides a foot adaptive support adjustment method based on a biomechanical model, which solves the problem of frictional heat accumulation caused by the related footwear technology usually using uniform cushioning materials or simple partition structures.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: 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 comprises the following steps: S1: Foot biomechanical modeling: Obtain the user's foot geometry data through 3D scanning, combine it with gait analysis to collect dynamic load parameters, and build a personalized foot finite element model that meets the following requirements: , where σ is tissue stress, E is elastic modulus, ε is strain, and η is viscosity coefficient; S2: Stress distribution calculation: Sample at 10% intervals from 0% to 100% during the gait cycle to calculate the peak pressure point P at the sole-shoe contact interface. max and high shear force area S area ; S3: Material Gradient Design: According to P maxThe distribution determines the gradient material stiffness mapping relationship: E(x,y)=k·ln(P(x,y)+1)+E0, where x,y are the plantar coordinates, k is the adjustment coefficient, and E0 is the base modulus; S4: Adaptive structure realization: Gradient sole structure constructed by 3D printing, which includes: Layered material area: The forefoot area uses a positive gradient material, with the hardness increasing by 5% to 15% from the surface to the inner layer; the arch area uses a negative gradient material, with the hardness decreasing by 8% to 12% from the surface to the inner layer; Microstructure unit: In S area The area is set with a non-uniform honeycomb structure, and the cell 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 under 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 gas chamber.

[0006] By adopting the above technical solution, a finite element model was constructed. At the same time, the stress distribution calculation module discretely sampled at a 10% phase interval during the gait cycle to calculate the pressure distribution on the sole-shoe interface and extract the peak pressure points and high shear force areas. Simultaneously, the material topology optimization module established a stiffness mapping function. This logarithmic function achieved load dispersion through nonlinear stiffness growth in the high-pressure area. Finally, a gradient sole structure was manufactured through multi-material 3D printing, including: a positive gradient in the forefoot of the layered material area to enhance pedaling energy feedback, and a negative gradient in the arch to improve support compliance. The microstructure unit generated a non-uniform honeycomb with a wall thickness that varied with the pressure gradient in the high shear force area to control the shear stress. The dynamic response cavity set an air chamber under the calcaneus according to the formula V=V0·e (-β·F) Compression to achieve adaptive dissipation of impact energy.

[0007] Preferably, the finite element model in step S1 includes the following anatomical structure divisions: calcaneal region, lateral arch region, medial arch region, first metatarsal region, second-third metatarsal region, fourth-fifth metatarsal region and phalangeal region.

[0008] Preferably, the high shear force area in step S2 is an area where the shear force is greater than 1.5 times the average value and lasts for more than 15% of the gait cycle.

[0009] 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.

[0010] Preferably, the honeycomb configuration of the microstructure unit is: a hexagonal honeycomb is used in the pressure gradient region |▽P|≥0.3MPa / cm, a quadrilateral honeycomb is used in the region 0.1MPa / cm≤|▽P|<0.3MPa / cm, and a triangular honeycomb is used in the region |▽P|<0.1MPa / cm.

[0011] Preferably, the air chamber 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 film is provided on the top of the cavity.

[0012] Preferably, a bionic tendon structure is provided in the arch support area, and a unidirectionally stretched fiber bundle is embedded in an elastic matrix, and the fiber bundle angle γ is inversely proportional to the arch height H: γ=40°-0.8H.

[0013] Preferably, the value of E0 in step S3 is dynamically adjusted based on the arch type: for flat feet, E0=3.5±0.3MPa; for normal arches, E0=2.8±0.2MPa; and for high arches, E0=2.0±0.2MPa.

[0014] Preferably, the Shore hardness H of the silicone damping film and the user's weight W satisfy: H=0.25W+40, and the thickness is 0.5±0.1 mm.

[0015] Preferably, a flexible hinge structure is provided in the phalangeal region, and its bending stiffness K b Negatively correlated with the toe joint flexion angle θ: K b =12-0.1θ.

[0016] The present invention provides a method for adaptive foot support adjustment based on a biomechanical model, which has the following beneficial effects: 1. The present invention uses a dual threshold to determine the high shear force area and deploys a pressure gradient adaptive non-uniform honeycomb structure and configuration grading in this area, thereby dynamically regulating local deformation during the extension and landing periods, thereby achieving the effect of reducing the stress peak in the high shear area and reducing frictional heat accumulation.

[0017] 2. The present invention collaboratively determines the stiffness of the shoe material through the adjustment coefficient k associated with the user's BMI and the base modulus E0 dynamically adjusted according to the arch type, so that the material stiffness distribution matches the individual load characteristics, achieving the effect of optimizing the full plantar pressure heterogeneity index.

[0018] 3. The present invention constructs a finite element model including the calcaneal area, the medial and lateral areas of the arch, the metatarsal area and the phalangeal area, and sets the partition boundary conditions and elastic coupling mechanism, so as to simulate the dynamic mechanical response of each anatomical structure during the gait cycle, provide a high-fidelity biomechanical basis for stress distribution calculation and material gradient design, and support the effect of reducing positioning errors.

[0019] 4. The fiber angle control of the bionic tendon in the arch area of ​​the present invention and the variable stiffness design of the flexible hinge in the toe bone area cooperate with the negative gradient hardness and positive gradient hardness of the layered material area, thereby enhancing the anti-collapse ability of the arch in the middle stage of gait support and reducing the bending resistance of the toe joint in the push-off phase, thereby achieving the effect of reducing kinetic energy loss in the gait cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a flow chart of the foot adaptive support adjustment method based on the biomechanical model proposed by the present invention. DETAILED DESCRIPTION

[0021] The following will clearly and completely describe the technical solution of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0022] Please see the attached Figure 1 The embodiment of the present 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 comprises the following steps: S1: Foot biomechanical modeling: Obtain the user's foot geometry data through 3D scanning, combine it with gait analysis to collect dynamic load parameters, and build a personalized foot finite element model that meets the following requirements: , where σ is tissue stress, E is elastic modulus, ε is strain, and η is viscosity coefficient; S2: Stress distribution calculation: Sample at 10% intervals from 0% to 100% during the gait cycle to calculate the peak pressure point P at the sole-shoe contact interface. max and high shear force area S area ; S3: Material Gradient Design: According to 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 plantar coordinates, k is the adjustment coefficient, and E0 is the base modulus; S4: Adaptive structure realization: Gradient sole structure constructed by 3D printing, which includes: Layered material area: The forefoot area uses a positive gradient material, with the hardness increasing by 5% to 15% from the surface to the inner layer; the arch area uses a negative gradient material, with the hardness decreasing by 8% to 12% from the surface to the inner layer; Microstructure unit: In S area The area is set with a non-uniform honeycomb structure, and the cell 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 under 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.

[0023] Specifically, the foot biomechanics modeling module first obtains the precise geometric contours of the user's foot, and at the same time, the gait analysis device is used to collect dynamic load time series data during walking. Based on these two types of data, the module constructs a personalized foot finite element model that includes viscoelastic properties. The stress distribution calculation module then discretizes and samples at 10% phase intervals during the gait cycle, and then calculates the pressure distribution at the sole-shoe contact interface at each phase, extracting the peak pressure point P. max and high shear force area S area ; At the same time, the material topology optimization module is based on P max The spatial mapping relationship of material stiffness is established by distribution: E(x,y)=k·ln(P(x,y)+1)+E0, where (x,y) is the plantar coordinate, k is the adjustment coefficient associated with body weight, and E0 is the base modulus related to the arch type. This logarithmic function ensures that the stiffness of the material in the high-pressure area increases nonlinearly to disperse the load; finally, a gradient sole structure is achieved through multi-material 3D printing technology: in the layered material area, the forefoot adopts a positive gradient design to enhance energy feedback during the extension period, and the arch adopts a negative gradient design to improve support compliance; in the microstructure unit area, for the high shear force area S area A non-uniform honeycomb structure with wall thickness that changes with the pressure gradient is generated, and shear stress is controlled through local deformation. In the dynamic response cavity design, the semi-enclosed air chamber under the calcaneus is compressed exponentially according to the load F, achieving adaptive dissipation of impact energy.

[0024] The finite element model in step S1 includes the following anatomical structure divisions: calcaneal region, lateral arch region, medial arch region, first metatarsal region, second-third metatarsal region, fourth-fifth metatarsal region, and phalangeal region.

[0025] Specifically, the model divides the sole of the foot into seven zones based on the biomechanical function of the foot. The calcaneal zone is the load-bearing area at the rear end of the foot, and the model captures its geometric shape and bony structure characteristics; the lateral arch zone and the medial arch zone correspond to the support surfaces of the lateral longitudinal arch and the medial longitudinal arch of the foot, respectively. The model simulates the dynamic deformation behavior of the arch during gait by distinguishing the morphological differences between the two. In the forefoot area, the model divides the metatarsals into three zones: the first metatarsal zone is independently modeled to reflect the biomechanical characteristics of the big toe when bearing weight, the second and third metatarsal zones are merged into a whole to simulate the coordinated load transfer mechanism during the midfoot transition period, and the fourth and fifth metatarsal zones jointly represent the stress distribution pattern of the lateral arch during the extension period; the terminal phalangeal zone covers all phalanges and metatarsophalangeal joints, and the model describes the stress conduction path during their flexion process; The above partition structure is applied in S2: the partition boundary conditions are set as the physiological motion constraints of each anatomical structure, and the mechanical coupling between partitions is achieved through elastic connections. This allows the contact pressure P and shear force τ of each area to be calculated independently in each phase of the gait cycle, and provides a spatial positioning reference for the material gradient design in S3, thus forming a modeling framework that aligns the anatomical structure with functional requirements.

[0026] 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.

[0027] Specifically, in S2, the criteria for determining the high shear stress region are implemented through dual mechanical and time thresholds: Mechanical threshold: Based on the calculation results of the finite element model at each phase of the gait cycle, the arithmetic mean value τ of the shear force of the entire plantar contact interface is first calculated. - ; Time threshold: Identify when the shear force exceeds the critical value of 1.5τ - The over-limit state must be maintained for at least three consecutive sampling phases; Applying this judgment standard to S4, the S area The region will serve as the layout location of the honeycomb structure, and its duration is required to ensure that the deformation response of the honeycomb structure is synchronized with the shear force accumulation phase during gait.

[0028] The adjustment coefficient k in step S3 is determined as follows: k=0.01·BMI+0.7, where BMI is the user's body fat index.

[0029] 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. The linear term coefficient 0.01 in the formula ensures the sensitive response of the material stiffness to the load difference, and the constant term 0.7 is used to maintain the basic support stiffness; k converts the stress distribution calculation results into the 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 stiffness curve of the sole material is steeper due to the increase in k value to match the higher load requirements.

[0030] The honeycomb configuration of the microstructure unit is: hexagonal honeycomb is used in the pressure gradient area |▽P|≥0.3MPa / cm, quadrilateral honeycomb is used in the area 0.1MPa / cm≤|▽P|<0.3MPa / cm, and triangular honeycomb is used in the area |▽P|<0.1MPa / cm.

[0031] Specifically, the selection of honeycomb configuration is strictly regulated by spatial partitioning based on the pressure gradient amplitude: High-pressure gradient zone: adopts a hexagonal honeycomb configuration, and its isotropic high stiffness can resist the drastic pressure changes during heel strike or late extension; Medium pressure gradient zone: A quadrilateral honeycomb configuration is used to adapt to the shear-compression composite load of the arch transition zone through orthotropic deformation capability; Low-pressure gradient zone: A triangular honeycomb configuration is deployed to maintain the flexible bending requirements of the phalangeal area with a low-density and lightweight structure.

[0032] The wall thickness distribution of the dynamic response cavity satisfies the following conditions: the outer wall thickness δ1=1.2δ2, where δ2 is the inner wall thickness, and a silicone damping film is set on the top of the cavity.

[0033] Specifically, the air chamber wall thickness distribution and damping settings are differentiated by design based on the biomechanical characteristics of the calcaneal area: 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, it can resist the eversion torque during the heel strike period; at the same time, a silicone damping film is set at the heel contact interface at the top of the air chamber. The damping film converts the kinetic energy generated by the gas compression process into heat energy, synergistically inhibiting the lateral expansion of the air chamber and resonating with the air pressure, thereby reducing the pressure on the arch of the foot.

[0034] A bionic tendon structure is set up in the arch support area, and a unidirectional stretched fiber bundle is embedded in the elastic matrix. The fiber bundle angle γ is inversely proportional to the arch height H: γ=40°-0.8H.

[0035] 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 γ of the low arch is increased to enhance the anti-collapse ability, and the γ of the high arch is reduced to avoid excessive lifting. At the same time, it forms a functional complement with 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.

[0036] 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.

[0037] 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 of the inner and outer arch partitions and the load distribution pattern 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. The Shore hardness H of the silicone damping film and the user's weight W satisfy: H=0.25W+40, and the thickness is 0.5±0.1mm.

[0038] Specifically, the Shore hardness H is bound to the user's physiological characteristics through the formula H=0.25W+40, where the coefficient 0.25 comes from the fact that for every 1kg increase in body weight, the hardness needs to be increased by 0.25A to maintain a kinetic energy absorption model with a constant deformation rate. The constant term 40 ensures the buffering threshold under a basic weight of 60kg; the thickness is simultaneously limited to 0.5±0.1mm to balance the damping rate and durability.

[0039] A flexible hinge structure is set in the phalangeal region, and its bending stiffness Kb is negatively correlated with the flexion angle θ of the phalangeal joint: Kb=12-0.1θ.

[0040] Specifically, the material topology optimization module automatically calculates the Kb value based on S2's gait phase data, and converts it into the material density distribution in the hinge area through 3D printing, so that it works synergistically with the positive gradient design of the layered material area in the phalangeal area. As the flexion angle increases, the stiffness decreases, reducing the bending resistance. The synchronous positive gradient material provides longitudinal support, jointly improving the propulsion force transmission efficiency.

[0041] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention 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 comprises the following modules: a foot biomechanics modeling module, a stress distribution calculation module, and a material topology optimization module; and the method comprises the following steps: S1: Foot biomechanical modeling: Obtain the user's foot geometry data through 3D scanning, combine it with gait analysis to collect dynamic load parameters, and build a personalized foot finite element model that meets the following requirements: , where σ is tissue stress, E is elastic modulus, ε is strain, η is viscosity coefficient, and dε / dt represents strain rate, i.e., the rate of change of strain ε with time t; S2: Stress distribution calculation: Sample at 10% intervals from 0% to 100% during the gait cycle to calculate the peak pressure point P at the sole-shoe contact interface. max and high shear force area S area ; S3: Material Gradient Design: According to 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 contact pressure of the sole at the specified coordinates in two-dimensional space, x,y are the sole coordinates, k is the adjustment coefficient, and E0 is the base modulus; S4: Adaptive structure realization: Gradient sole structure constructed by 3D printing, which includes: Layered material area: The forefoot area uses a positive gradient material, with the hardness increasing by 5% to 15% from the surface to the inner layer; the arch area uses a negative gradient material, with the hardness decreasing by 8% to 12% from the surface to the inner layer; Microstructure unit: In S area The area is set with a non-uniform honeycomb structure, and the cell 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 under 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 gas chamber.

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

3. The method for adaptive foot support adjustment based on a biomechanical model according to claim 1, characterized in that: 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.

4. The method for adaptive foot support adjustment based on a biomechanical model according to claim 1, characterized in that: 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.

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

6. The method for adaptive foot support adjustment based on a biomechanical model according to claim 1, characterized in that: The air chamber 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 film is set on the top of the cavity.

7. The method for adaptive foot support adjustment based on a biomechanical model according to claim 1, characterized in that: A bionic tendon structure is set up in the arch support area, and a unidirectional stretched fiber bundle is embedded in the elastic matrix. The fiber bundle angle γ is inversely proportional to the arch height H: γ=40°-0.8H.

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

9. The method for adaptive foot support adjustment based on a biomechanical model according to claim 1, characterized in that: The Shore hardness H of the silicone damping film and the user's weight W satisfy: H=0.25W+40, and the thickness is 0.5±0.1mm.

10. The method for adaptive foot support adjustment based on a biomechanical model according to claim 1, characterized in that: A flexible hinge structure is set in the phalangeal area, and its bending stiffness K b Negatively correlated with the toe joint flexion angle θ: K b =12-0.1θ.

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