Method and system for measuring elasticity modulus of human body

Abstract

The invention provides a human body elasticity modulus measuring method and system, and relates to the technical field of computer application, and the method comprises the following steps: applying different normal pressures on calibration points on human body surfaces of subjects with different body fat rates; obtaining a three-dimensional image of the compression deformation of the calibration point through three-dimensional scanning; according to the corresponding three-dimensional images of the calibration point under different normal pressures, determining press-in profile curves under different pressures; according to the press-in profile curve, the press-in depth of a calibration point is determined; according to the press-in depth, the human body effective elastic modulus of the mark point is obtained. According to the technical scheme, the shape characteristics of the pressed human body can be directly obtained, the method is more visual and accurate, the method has the characteristics of high resolution and high precision, the elastic modulus of different parts of the human body can be obtained, and more accurate data can be provided for construction of the elastic digital human body.

Description

Technical Field

[0001] The present application relates to the field of computer application technology, and in particular to a method and system for measuring human elastic modulus. Background Art

[0002] Most of the three-dimensional human models in the clothing virtual simulation system are rigid, lacking simulation of human body deformation under pressure, and it is difficult to reflect the real simulation effect of clothing pressure on human body deformation. However, the elastic modulus of different parts of the real human body varies greatly, and the factors affecting the elastic modulus of different parts are also different. Therefore, exploring the elastic modulus of various parts of the human body is of great significance to the construction of elastic digital human bodies in clothing virtual simulation systems, as well as the measurement of human elastic modulus in the fields of medicine and sports science.

[0003] At present, the elastic modulus test of human tissue mainly includes indentation method, suction method, shear test method, etc. The research usually discusses and studies the skin, subcutaneous tissue and bone composite tissue separately, and uses in vitro experiments or biosimulation materials for research, but there are problems such as cumbersome test steps and low stability, and the experimental results will be affected by the lack of biological activity and poor simulation effect. Some scholars use in vivo experiments to take two-dimensional images to calculate the elastic modulus of the human body surface, and the image acquisition effect is greatly affected by the equipment, the pressure site and the external environment, which in turn affects the comprehensive and accurate calculation and determination of the elastic modulus of the human body surface. On the other hand, in vivo experiments often choose any point on the forearm for measurement and research. The experimental results are not widely referenced due to the limitation of the experimental samples, and the reference that can be provided for other parts is also extremely limited. Summary of the invention

[0004] The purpose of the present invention is to provide a method and system for measuring the elastic modulus of a human body in order to solve the problem of low accuracy of the existing method for measuring the elastic modulus of the human body surface.

[0005] The above-mentioned purpose of the present application is achieved through the following technical solutions: S1: Apply normal pressures of different magnitudes to the calibration points on the body surface of subjects with different body fat percentages; S2: Obtain a three-dimensional image of the compression deformation of the calibration point through three-dimensional scanning; S3: determining the indentation profile curves under different pressure magnitudes according to the three-dimensional images corresponding to the different normal pressure magnitudes of the calibration points; S4: Determine the indentation depth of the calibration point according to the indentation profile curve; S5: According to the indentation depth, the effective elastic modulus of the human body at the marked point is obtained.

[0006] Optionally, step S3 includes: S31: performing smoothing and hole filling processing on the three-dimensional image to obtain an optimized three-dimensional image; S32: intercepting the compressed cross section of the optimized three-dimensional image to obtain a compression profile curve.

[0007] Optionally, step S31 includes: detecting and flattening single-point peaks on the polygonal mesh of the three-dimensional image for smoothing to obtain a smoothed image; and filling the smoothed image with a curvature filling method to obtain an optimized three-dimensional image.

[0008] Optionally, step S4 includes: S41: obtaining the indentation depth of a marked point under normal pressures of different magnitudes from the indentation profile curve; S42: Calculate the normal pressure and the pressure depth to obtain a stress-strain fitting curve of the calibration point; the normal pressure represents the normal stress of the calibration point, and the pressure depth represents the normal strain of the calibration point.

[0009] Optionally, step S5 includes: According to the relevant formula of Hertz contact mechanics theory, combined with the indentation depth, the effective elastic modulus of the human body at different marking points is obtained. The relevant formula of Hertz contact mechanics theory is as follows:

[0010] In the formula, is the contact stress, in MPa; is the normal pressure, in N; L is the contact line length, in mm; is the comprehensive curvature radius, in mm; and are the Poisson's ratios of the two contact materials respectively; is the elastic modulus of the two contact materials, in MPa; is the elastic coefficient of the material.

[0011] A human body surface elastic modulus measurement system, the system comprising: a push-pull dynamometer, a three-dimensional scanner, a computer, and a display; The push-pull force gauge is used to measure the magnitude of normal pressure; The three-dimensional scanner is used to obtain a three-dimensional image; The computer is used to calculate the three-dimensional image and the normal pressure to obtain the effective elastic modulus of the human body; The display is used for visually displaying the effective elastic modulus of the human body.

[0012] An electronic device comprises a processor, a memory, a user interface and a network interface, wherein the memory is used to store instructions, the user interface and the network interface are used to communicate with other devices, and the processor is used to execute the instructions stored in the memory so that the electronic device executes a method for measuring the elastic modulus of the human body.

[0013] A computer-readable storage medium stores instructions. When the instructions are executed, a method for measuring the elastic modulus of a human body is executed.

[0014] The beneficial effects of the technical solution provided by this application are: The spherical pressure head is used to apply normal pressures of different magnitudes to different calibration points of human bodies with different body fat percentages; a three-dimensional image of the human body surface under pressure deformation is obtained by three-dimensional scanning; and the effective elastic modulus of the human body is calculated by the normal pressure and the three-dimensional image. The technical solution of the present invention can directly obtain the morphological characteristics of the human body under pressure, which is more intuitive and accurate, has the characteristics of high resolution and high precision, and can obtain the elastic modulus of different parts of the human body. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The present application will be further described below with reference to the accompanying drawings and embodiments, in which: Figure 1 A step diagram of a method for measuring elastic modulus of a human body according to an embodiment of the present invention; Figure 2 A schematic diagram of a press-in test model according to an embodiment of the present invention; Figure 3 A three-dimensional image after compression according to an embodiment of the present invention; Figure 4 An optimized three-dimensional image according to an embodiment of the present invention; Figure 5 A schematic diagram of human body calibration points according to an embodiment of the present invention; Figure 6 A line graph showing the depth of penetration at different points of a subject with a high body fat percentage according to an embodiment of the present invention; Figure 7 A line graph showing the surface elastic modulus values ​​at different points of a subject with a high body fat percentage according to an embodiment of the present invention; Figure 8 It is a schematic diagram of the structure of an electronic device for measuring the elastic modulus of a human body in an embodiment of the present application. DETAILED DESCRIPTION

[0016] In order to have a clearer understanding of the technical features, purposes and effects of the present application, the specific implementation methods of the present application are now described in detail with reference to the accompanying drawings.

[0017] The embodiments of the present application provide a method for measuring the elastic modulus of a human body.

[0018] Please refer to Figure 1 , Figure 1 : is a step diagram of a method for measuring the elastic modulus of a human body in an embodiment of the present application, comprising: S1: Apply normal pressures of different magnitudes to the calibration points on the body surface of subjects with different body fat percentages through a spherical indenter; S2: Obtain a three-dimensional image of the compression deformation of the calibration point through three-dimensional scanning; S3: determining the indentation profile curves under different pressure magnitudes according to the three-dimensional images corresponding to the different normal pressure magnitudes of the calibration points; Step S3 includes: S31: performing smoothing and hole filling processing on the three-dimensional image to obtain an optimized three-dimensional image, specifically as follows: detecting and flattening single-point peaks on the polygonal mesh of the three-dimensional image to perform smoothing processing to obtain a smoothed image; and filling the smoothed image using a curvature filling method to obtain an optimized three-dimensional image; S32: intercepting the compressed cross section of the optimized three-dimensional image to obtain a compression profile curve.

[0019] Specifically, Figure 3 A three-dimensional image after compression according to an embodiment of the present invention; Figure 4 This is an optimized three-dimensional image according to an embodiment of the present invention.

[0020] S4: Determine the indentation depth of the calibration point according to the indentation profile curve; Step S4 includes: S41: obtaining the indentation depth of a marked point under normal pressures of different magnitudes from the indentation profile curve; S42: Calculate the normal pressure and the pressure depth to obtain a stress-strain fitting curve of the calibration point; the normal pressure represents the normal stress of the calibration point, and the pressure depth represents the normal strain of the calibration point.

[0021] Specifically, the overall contour of the indenter is fitted according to the contour of the indenter in the indentation profile curve, and the center of the indenter circle is determined according to the overall contour of the indenter. If the indenter diameter is known, the indentation depth is calculated by proportional conversion, which specifically includes: first determining the center point of the circle, then drawing a vertical line, drawing the indentation depth and the diameter of the circle, and then using a ruler to measure the length of the two lines. If the circle diameter is known to be 10mm, the indentation depth is converted.

[0022] Specifically, based on the indentation depth data obtained from the experiment, a compression depth line graph is drawn to present the comparison of indentation depths of various points under different pressures, such as Figure 6 The depth of penetration at different points of subjects with high body fat percentage.

[0023] S5: According to the indentation depth, the effective elastic modulus of the human body at the marked point is obtained.

[0024] Step S5 includes: According to the relevant formula of Hertz contact mechanics theory, combined with the indentation depth, the effective elastic modulus of the human body at different marking points is obtained. The relevant formula of Hertz contact mechanics theory is as follows:

[0025] In the formula, is the contact stress, in MPa; is the normal pressure, in N; L is the contact line length, in mm; is the comprehensive curvature radius, in mm; and are the Poisson's ratios of the two contact materials respectively; is the elastic modulus of the two contact materials, in MPa; is the elastic coefficient of the material.

[0026] Specifically, according to the relevant formula (1) of Hertz contact mechanics theory, the effective elastic modulus of the human body at different points is obtained (such as Figure 7 shown).

[0027] Specifically, the calibration points for the leg experiment need to cover as much skin surface area as possible. The horizontal circle of the thigh root, the horizontal circle between the thigh root and the knee, the horizontal circle of the knee, the horizontal circle of the thickest part of the calf, and the horizontal circle above the ankle are recorded as A1, A2, A3, A4, and A5; the front midline of the leg is recorded as B1; the vertical direction of the inner side of the leg is recorded as B2; the back midline of the leg is recorded as B3; and the outer midline of the leg is recorded as B4. In this way, 20 points where five horizontal lines intersect with four vertical lines are obtained, which are the 20 calibration points of the experiment, such as Figure 5 shown.

[0028] Before the experiment begins, use four black reflective markers to stick around the experimental calibration points to determine the location of the calibration points. When the push-pull dynamometer displays values ​​of 1N, 2N, 3N (±0.3N), keep the dynamometer horizontally and place it at a position perpendicular to the calibration points. Slowly press it into the skin and use a 3D scanner to scan the pressed area. The schematic diagram of the press-in experiment is shown in the figure below. Figure 2 .

[0029] Among them, the push-pull force gauge is a mechanical measuring instrument used for push and pull tests. It is small in size and easy to operate. It can be held in hand or used in combination with various fixtures for measurement. It can provide upper and lower limit alarms during the experiment, and issue an alarm when the bearing capacity is exceeded to ensure the safety of the experiment. The digital display push-pull force gauge is easy to read. This experiment uses a push-pull force gauge with an accuracy of three decimal places, and the test accuracy is high. The measurement units include Newton, kilograms, and pounds-force, and the units can be switched.

[0030] 3D scanning technology is a high-precision method for capturing the surface features of an object or environment. A 3D scanner projects light onto an object through an optical system, collects detailed data about the appearance of the object by receiving the reflected light, and obtains the outline and shape of the measured object. These data are then used in the process of 3D reconstruction, that is, building an accurate model of the object in digital space. 3D scanners achieve model construction by recording point cloud data of the geometric structure of the object surface. The density of these data points directly affects the accuracy and details of the model. High-density point cloud data can generate more accurate surface shapes. In addition, color 3D scanners can not only capture the geometric shape of the object, but also obtain the color information of the object surface. Using this color data, material mapping can be applied to the reconstructed 3D model, thereby enhancing the visual authenticity of the model. This method makes the digital model not only consistent with the original object in shape, but also as close to the real object as possible in color and texture, providing a high degree of simulation for the display of objects in the virtual environment.

[0031] When selecting the indenter, a spherical indenter is selected, which is suitable for hardness tests of most metal materials and non-metallic materials, and the test results are accurate. Compared with other types of indenters, the spherical indenter has a unique characteristic, that is, the stress and strain fields generated in the contact area are significantly different. Since the contact stress of the spherical indenter is relatively low, the material is mainly elastically deformed in the initial stage of the experiment. Theoretically, the spherical indenter can be used to determine the yield stress and work hardening behavior of the material, and can simulate the stress-strain curve of the entire uniaxial tensile test through a single indentation curve. This advantage will be more significant when the radius of the spherical indenter is larger. In addition, the spherical indenter is particularly suitable for measuring the elastic modulus of soft materials and evaluating contact damage. The indenter material is carbon steel with a diameter of 10mm.

[0032] In this embodiment, a 3D scanner can be used to observe the stress deformation of the human body surface and record the 3D deformation image. The 3D image of the stress point can be segmented and extracted from the overall 3D image. Image smoothing and curvature filling are used to optimize the image, and the indentation profile curve is intercepted to obtain the indentation depth of the human body calibration point under different pressures, and then the elastic modulus is obtained. Not only can the slight deformation under small stress be identified, but also the interference of human body shape differences on the measurement can be avoided, the image processing steps are simplified, and the accuracy is improved, which can provide more accurate data support for ergonomic research.

[0033] The significance analysis was performed based on the penetration depth of subjects with different body fat percentages at different pressures at the same calibration point. To verify the feasibility and accuracy of this method, a unit model was constructed based on the average thickness from the bone to the skin surface of the female body. By applying boundary conditions consistent with the method, the normal stress magnitude in the calculation results was observed and compared with the normal stress magnitude in the actual experimental process, as shown in Table 1.

[0034] Table 1 Comparison of experimental and finite element normal load (kPa)

[0035] The two-tailed significance of the independent sample T test of the measurement results of the two methods is p=0.774>>0.05, and there is no significant difference between the two methods. It can be seen that the above-mentioned automatic measurement method, that is, the method of this embodiment, has high accuracy in measuring the elastic modulus, and is simple to operate, highly efficient, and has strong anti-interference ability.

[0036] The present application also discloses an electronic device. Figure 8 , Figure 8 The electronic device 500 may include: at least one processor 501 , at least one network interface 504 , a user interface 503 , a memory 505 , and at least one communication bus 502 .

[0037] The communication bus 502 is used to realize the connection and communication between these components.

[0038] The user interface 503 may include a display screen, and the optional user interface 503 may also include a standard wired interface or a wireless interface.

[0039] The network interface 504 may optionally include a standard wired interface or a wireless interface (such as a WI-FI interface).

[0040] The present application also discloses a computer-readable storage medium, which stores a plurality of instructions, and the instructions are suitable for a processor to load to execute the above-mentioned method for measuring the elastic modulus of a human body.

[0041] The above are only exemplary embodiments of the present disclosure and cannot be used to limit the scope of the present disclosure. That is, any equivalent changes and modifications made according to the teachings of the present disclosure are still within the scope of the present disclosure. After considering the disclosure of the specification and the truth of practice, those skilled in the art will easily think of other embodiments of the present disclosure.

[0042] This application is intended to cover any variation, use or adaptation of the present disclosure, which follows the general principles of the present disclosure and includes common knowledge or customary technical means in the art not described in the present disclosure. The description and examples are to be regarded as exemplary only, and the scope and spirit of the present disclosure are defined by the claims.

Claims

1. A method for measuring human elastic modulus, characterized in that: The method comprises the following steps: S1: Apply normal pressures of different magnitudes to the calibration points on the body surface of subjects with different body fat percentages; S2: Obtain a three-dimensional image of the compression deformation of the calibration point through three-dimensional scanning; S3: determining the indentation profile curves under different pressure magnitudes according to the three-dimensional images corresponding to the different normal pressure magnitudes of the calibration points; S4: Determine the indentation depth of the calibration point according to the indentation profile curve; S5: According to the indentation depth, the effective elastic modulus of the human body at the marked point is obtained.

2. A method for measuring human elastic modulus as claimed in claim 1, characterized in that: Step S3 includes: S31: performing smoothing and hole filling processing on the three-dimensional image to obtain an optimized three-dimensional image; S32: intercepting the compressed cross section of the optimized three-dimensional image to obtain a compression profile curve.

3. A method for measuring human elastic modulus as claimed in claim 2, characterized in that: Step S31 includes: detecting and flattening the single-point peak on the polygonal mesh of the three-dimensional image for smoothing to obtain a smoothed image; and filling the smoothed image with a curvature filling method to obtain an optimized three-dimensional image.

4. A method for measuring human elastic modulus as claimed in claim 1, characterized in that: Step S4 includes: S41: obtaining the indentation depth of a marked point under normal pressures of different magnitudes from the indentation profile curve; S42: Calculate the normal pressure and the pressure depth to obtain a stress-strain fitting curve of the calibration point; the normal pressure represents the normal stress of the calibration point, and the pressure depth represents the normal strain of the calibration point.

5. A method for measuring human elastic modulus as claimed in claim 1, characterized in that: Step S5 includes: According to the relevant formula of Hertz contact mechanics theory, combined with the indentation depth, the effective elastic modulus of the human body at different marking points is obtained. The relevant formula of Hertz contact mechanics theory is as follows: In the formula, is the contact stress, in MPa; is the normal pressure, in N; L is the contact line length, in mm; is the comprehensive curvature radius, in mm; and are the Poisson's ratios of the two contact materials respectively; is the elastic modulus of the two contact materials, in MPa; is the elastic coefficient of the material.

6. A human body surface elastic modulus measurement system, used to implement a human body elastic modulus measurement method as described in claims 1-5, characterized in that: The system includes: a push-pull force meter, a three-dimensional scanner, a computer, and a display; The push-pull force gauge is used to measure the magnitude of normal pressure; The three-dimensional scanner is used to obtain a three-dimensional image; The computer is used to calculate the three-dimensional image and the normal pressure to obtain the effective elastic modulus of the human body; The display is used for visually displaying the effective elastic modulus of the human body.

7. An electronic device, characterized in that: The electronic device comprises a processor (501), a memory (505), a user interface (503) and a network interface (504), wherein the memory (505) is used to store instructions, the user interface (503) and the network interface (504) are used to communicate with other devices, and the processor (501) is used to execute the instructions stored in the memory (505) so that the electronic device executes the method according to any one of claims 1 to 5.

8. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores instructions, and when the instructions are executed by a computer, the method steps according to any one of claims 1 to 5 are performed.

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