Personalized porous protector design method based on skin temperature field driving

Abstract

The invention relates to the technical field of medical rehabilitation equipment and computer aided design crossing, particularly discloses a personalized porous protector design method based on skin temperature field driving, and belongs to the technical field of medical rehabilitation equipment and computer aided design crossing. Comprising the following steps that a three-dimensional scanner is used for obtaining a protector initial model matched with an affected limb, an infrared thermal imager is used for extracting a skin surface temperature field wearing porous protectors with different porosities, and a mapping relation model of the temperature field and the porosities is constructed according to the Boltzmann law of radiation and a radiation heat exchange calculation formula between a human body and an indoor environment. According to the personalized porous protective tool design method based on skin temperature field driving, the defects that a traditional protective tool is poor in air permeability, heavy and the like are overcome, personalized porous protective tool customization can be conducted according to different affected limbs of different patients, and the personalized porous protective tool design method has the advantages of being high in thermal comfort, light in weight, high in fitting degree and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of intersection of medical rehabilitation equipment and computer-aided design, and in particular to a method for designing personalized porous protective gear driven by skin temperature field. Background Art

[0002] Orthopedic fractures are one of the most common surgical conditions, and plaster braces are often used for fixation in clinical practice. However, traditional plaster braces generally have defects such as poor breathability, insufficient waterproofness, heavy weight, and low thermal comfort. Especially in the hot summer, long-term wear can easily lead to complications such as bacterial growth and skin infections. With the improvement of living standards, patients have an increasing demand for lightweight, well-fitting, and comfortable braces, and traditional manufacturing processes are unable to meet personalized needs. Although digital design and 3D printing technology have significantly improved the personalized manufacturing capabilities of orthopedic braces, their thermal comfort is still limited by the performance of the substrate, the fit of the model, and the ability to control temperature.

[0003] Reverse modeling based on 3D scanning point cloud data (SolidWorks / UG and other software) can achieve the construction of high-precision personalized protective gear models. Methods based on infrared thermal imaging and human-computer interactive design combined with multiple rules and random porous structures are also often used for the optimization design of thermal comfort porous structures. During the design process, the gradient distribution and porosity design of the porous structure are highly subjective, poorly correlated with the temperature distribution, and lack a quantitative relationship between the skin temperature field and the porous area. This cannot support pore optimization, and it is difficult to ensure the universality and robustness of thermal comfort for different patients with different affected limbs.

[0004] How to establish quantitative design criteria based on the distribution characteristics of the skin temperature field, generate lightweight, gradient porous structures that match thermal comfort requirements through automated algorithms, break through the subjective limitations of traditional human-computer interaction design, and achieve coordinated optimization of the thermodynamic properties of personalized protective gear has become an urgent problem to be solved. Summary of the Invention

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: a porous structure design method based on skin temperature field drive, including the following core steps:

[0006] Step S1: reconstructing a three-dimensional model of protective gear matching the affected limb, wearing protective gear with different porosities and obtaining the skin surface temperature field, and constructing a mapping relationship model between "skin temperature field and structural porosity";

[0007] Step S2: Obtain the porous position and distribution of the temperature field at the macro level by using the isothermal surface area weighted random sampling method;

[0008] Step S3: Based on the obtained geodesic Voronoi diagram, closed geodesic B-splines in polar coordinates are used to precisely control the cell size, regulate the porosity of the structure at the microscopic level, and generate a porous protective gear model with a target porosity driven by the skin temperature field through bias and Boolean operations.

[0009] In step S1, the mapping relationship model between skin temperature field and structural porosity is constructed, which is specifically divided into the following three steps:

[0010] In the first step, to construct a mapping model between skin temperature field and structural porosity, Creaform's Go!SCAN SPAPK™ portable 3D scanner was used to acquire 3D point cloud data of the affected limb and reconstruct the model, resulting in a well-fitting initial model of the protective gear. A HIKMICRO-H11 infrared thermal imaging scanner was then used to extract surface temperature distribution data of the affected limb while wearing protective gear of varying porosity, thereby determining the skin temperature field.

[0011] In the second step, based on the Boltzmann radiation law, the total power Qr is:

[0012]

[0013] Where ε is the emissivity (the emissivity of the human body is about 0.97), σ is the Stefan-Boltzmann coefficient, and the blackbody is 5.67*10 -8 watt / m 2 K 4 , S is the effective radiation area, which can be obtained according to the DuBois formula, Trel is the average temperature of the actual state, and T0 is the average temperature of the initial state;

[0014] The total heat exchange power Qr between the human body and the indoor environment is:

[0015]

[0016] Where S' is the effective radiation area when wearing protective gear, and the porosity and weight coefficient need to be considered, which can be regarded as S' = ω y ·f eff S, fcl is the clothing area coefficient, which is the ratio of the total surface area of ​​the human body after clothing to the naked area. It is 1 when naked. Wearing protective gear does not change the total surface area of ​​the external body, so fcl is 1 in this case. feff is the effective radiation area coefficient of the human body, which is the ratio of the effective radiation area (S) to the total surface area (S0), that is, the porosity. Teff is the average skin temperature when wearing protective gear, and T0 is the average skin temperature in the natural state.

[0017] The third step is to convert the Boltzmann radiation law and the radiation heat transfer formula between the human body and the indoor environment. The corresponding "temperature field T and porosity feff" relationship function model is:

[0018]

[0019] Where T sv is the average temperature of the exposed skin at the pores of the protective gear, T csv is the average surface temperature of the protective gear, ω y is the porosity weight function;

[0020] Specifically, the porosity weight function empirical formula ω is obtained by fitting the printed models with different porosity ratios and the corresponding infrared thermal imaging experimental results. y for:

[0021] ω y =16151.26f eff 4 -26985.2f eff 3 +16730.07f eff 2 -4599.88f eff +484.53

[0022] In step 2, based on the isothermal surface area weighted random sampling method, the porous position and distribution matching the temperature field at the macro level are obtained. It is specifically divided into the following two steps:

[0023] In the first step, the temperature field data of the skin surface of the affected limb is used to extract the isothermal surfaces and calculate the area of ​​each isothermal surface. According to the proportion of the area of ​​each isothermal surface to the total area, random sampling is performed on the corresponding porous positions on the isothermal surface. The sampling probability ratio of each isothermal surface is calculated as follows:

[0024]

[0025] Where M is the number of isothermal surfaces, A i is the area of ​​the ith isothermal surface, A total is the total area of ​​the isothermal surface;

[0026] In the second step, weighted random sampling is performed within each isothermal surface according to the sampling probability ratio to obtain the location of the porous body, so as to match the porous body location and distribution of the temperature field distribution at the macro level and use them as Voronoi sites to generate a geodesic Voronoi diagram.

[0027] Step 3: Generate a porous model with target porosity based on the temperature field, which is divided into the following three steps:

[0028] In the first step, in order to achieve precise control of cell size at the microscopic level, a closed geodesic B-spline is generated on the geodesic polar coordinate parameterized two-dimensional plane based on the obtained geodesic Voronoi diagram. The B-spline point formula of the parameterized plane is as follows:

[0029]

[0030] Among them, N j，k (u) is the basis function of geodesic B-spline, P j is the control vertex of the geodesic B-spline, and u is the node parameter;

[0031] In the second step, by controlling the effective area of ​​the cell, the target porosity can be precisely controlled and the closed B-spline can be normal-biased;

[0032] Specifically, the control vertices of the spline are mapped to the parameterized plane through the method of geodesic polar coordinate parameterization. The mapping point of the Voronoi cell centroid on the plane is also the origin of the parameterized coordinates. The biased control point can be expressed as:

[0033] x′=tx i ,y′=ty i

[0034] Specifically, t is:

[0035]

[0036] Among them, A j is the area of ​​the jth Voronoi cell, A Bj is the area of ​​the closed B-spline corresponding to the j-th Voronoi cell;

[0037] In the third step, the Boolean difference operation is performed between the biased closed B-spline model and the initial protective gear model to obtain the target porosity porous protective gear model based on the temperature field.

[0038] It has the following beneficial effects:

[0039] 1. The present invention provides a method for designing a personalized porous protective gear structure based on skin temperature field drive. Based on the surface temperature field distribution of the affected limb skin, a "temperature field and porosity" mapping relationship model is established. This method enables the coordinated design of the temperature field and structural porosity, avoiding shortcomings such as insufficient temperature field correlation and strong subjectivity in porosity design. This method provides quantitative guidance for customized porous protective gear for different patients and different affected limbs.

[0040] 2. The present invention provides a method for designing a personalized porous protective gear structure driven by the skin temperature field. The temperature field is mapped to the porous protective gear structure in two levels: at the macro level, the isothermal surface area is used as a weight to obtain the porous position and distribution that matches the temperature field distribution; at the micro level, the size of the porous structure is precisely controlled by the geodesic B-spline curve in polar coordinates, avoiding the shortcomings of low robustness caused by human-computer interaction design, and improving the design efficiency and thermal comfort of personalized porous protective gear. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1is a diagram of method steps of an embodiment of the present invention;

[0042] Figure 2 is a detailed flow chart of an embodiment of the present invention;

[0043] Figure 3 It is a schematic diagram of a site for generating multiple well locations and distributions through probability proportional sampling in an embodiment of the present invention;

[0044] Figure 4 is a geodesic Voronoi diagram generated by an embodiment of the present invention;

[0045] Figure 5 is a geodesic Voronoi B-spline graph generated by an embodiment of the present invention;

[0046] Figure 6 This is the personalized porous protective gear model driven by the skin temperature field that is ultimately generated by the embodiment of the present invention. DETAILED DESCRIPTION

[0047] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the 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.

[0048] For the first example, please refer to Figures 1-6 The present invention provides a technical solution: a method for designing personalized porous protective gear based on skin temperature field drive, comprising the following steps:

[0049] S101: Perform a 3D scan of the affected limb and reconstruct the model to obtain an adapted initial model of the protective gear. Protective gear models with different porosities are designed and 3D printed. Infrared thermal imaging is used to detect the skin surface temperature field after wearing, and a mapping relationship model between "skin temperature field and structural porosity" is constructed.

[0050] S102, performing isothermal surface area weight calculation on the temperature field, obtaining randomly sampled porous sites with corresponding weights on each isothermal surface, generating porous locations and distributions that match the temperature field distribution at a macro level, and using them as Voronoi sites to generate a geodesic Voronoi diagram;

[0051] S103: Based on the obtained geodesic Voronoi diagram, a closed geodesic B-spline curve is constructed based on the site in the polar coordinate parameterized plane. By controlling the effective area of ​​the cell, the target porosity can be precisely controlled. After biasing, a Boolean operation is performed on the protective gear model to obtain a porous protective gear model with the target porosity.

[0052] Specifically, a three-dimensional model of the affected limb is scanned and reconstructed using a three-dimensional scanner, a certain thickness is set to obtain a high-fitting protective gear prototype, porous protective gear with different porosities is printed, and an infrared thermal imager is used to extract the corresponding skin surface temperature field, and a "skin temperature field and structural porosity" mapping relationship model is constructed. S1 includes the following steps:

[0053] The S11 was scanned using Creaform's Go!SCAN SPAPK™ portable 3D scanner. This device features 99 LED white light sources, eliminates the need for markers, and offers a maximum scanning accuracy of 0.05mm. The scanning area spans 390×390mm, enabling fast, efficient, and accurate acquisition of 3D point cloud data and model reconstruction of the affected limb. A 1mm scanning accuracy setting and a 3mm offset thickness yielded a well-fitting original model of the brace.

[0054] S12, using the HIKMICRO-H11 infrared thermal imaging scanner from Hikvision Micro-Image, which has 19,200 pixels, with the following scanning parameters: focal length 30 cm, emissivity 0.97, wearing protective gear in a room temperature environment (26.2°C) and maintaining a simple standing or sitting posture for 30 minutes, measuring the required temperature data of the arm after wearing the protective gear to obtain the temperature field of the affected limb skin.

[0055] S13, based on the Boltzmann radiation law, the total power Qr is:

[0056]

[0057] Where ε is the emissivity (the emissivity of the human body is about 0.97), σ is the Stefan-Boltzmann coefficient (the black body is 5.67*10 -8 watt / m 2 K 4 ), S is the effective radiation area, which can be obtained according to the DuBois formula, Trel is the average temperature of the actual state, and T0 is the average temperature of the initial state;

[0058] The total heat exchange power Qr between the human body and the indoor environment is:

[0059]

[0060] Where S' is the effective radiation area when wearing protective gear, and the porosity and weight coefficient need to be considered, which can be regarded as S' = ω y ·f effS, fcl is the clothing area coefficient, which is the ratio of the total surface area of ​​the human body after clothing to the naked area. It is 1 when naked. Wearing protective gear does not change the total surface area of ​​the external body, so fcl is 1 in this case. feff is the effective radiation area coefficient of the human body, which is the ratio of the effective radiation area S to the total surface area S0, that is, the porosity. Teff is the average skin temperature when wearing protective gear, and T0 is the ambient temperature.

[0061] S14, converting the Boltzmann radiation law and the radiation heat transfer formula between the human body and the indoor environment, the corresponding "temperature field T and porosity feff" relationship function model is:

[0062]

[0063] Where T is the average skin surface temperature in the indoor environment, T sv is the average temperature of the exposed skin at the pores of the protective gear, T csv is the average surface temperature of the protective gear, ω y is the porosity weight function;

[0064] S15, by printing different porosity models and corresponding infrared thermal imaging experimental results, under the conditions of ambient temperature T0 of 26.2℃ and T of 33.5℃, a polynomial fitting is performed to obtain the empirical formula of the porosity weight function ω y for:

[0065] ω y =16151.26f eff 4 -26985.2fe ff 3 +16730.07f eff 2 -4599.88f eff +484.53

[0066] Specifically, the skin surface temperature field obtained by S1 after wearing is obtained by weighted random sampling method based on isothermal surface area to obtain the porous position and distribution of the matching temperature field at the macro level. Figure 3 As shown, it is used as a Voronoi site to generate a geodesic Voronoi diagram as shown Figure 4 As shown, the S2 includes the following steps:

[0067] S21: Using the skin surface temperature field data of the affected limb, set the number of isothermal surfaces to be extracted to M, calculate the area of ​​each isothermal surface, and randomly sample the multi-hole positions on the corresponding isothermal surface based on the proportion of the area of ​​each isothermal surface to the total area. The sampling probability ratio of each isothermal surface is calculated as follows:

[0068]

[0069] Among them A i is the area of ​​the ith isothermal surface, A total is the total area of ​​the isothermal surface;

[0070] S22, set the total number of required porous bodies to 500, and perform proportional weighted random sampling within each isothermal surface according to the sampling probability ratio of each isothermal surface to obtain the corresponding number of points. All points are regarded as a point set, which can achieve the porous position and distribution of the temperature field distribution at the macro level, and then use them as Voronoi sites to obtain the corresponding geodesic Voronoi map.

[0071] Specifically, the geodesic Voronoi diagram obtained by S2 is used to make a closed B-spline curve based on the Voronoi site in the polar coordinate parameterized plane as follows Figure 5 As shown in the figure, by controlling the effective area of ​​the cell, the target porosity can be precisely controlled. After biasing, the target porosity porous protective gear model is obtained by performing Boolean operations with the protective gear model. Figure 6 As shown, the S3 includes the following steps:

[0072] S31, in order to achieve precise control of cell size at the microscopic level, we first generate closed geodesic B-splines on the geodesic polar coordinate parameterized two-dimensional plane based on the obtained geodesic Voronoi diagram. The B-spline point formula of the parameterized plane is as follows:

[0073]

[0074] Among them, N j，k (u) is the basis function of geodesic B-spline, P j is the control vertex of the geodesic B-spline, and u is the node parameter;

[0075] S32, by controlling the effective area of ​​the cell, the target porosity can be precisely controlled and the closed B-spline can be normal-biased;

[0076] Specifically, the control vertices of the spline are mapped to the parameterized plane through the method of geodesic polar coordinate parameterization. The mapping point of the Voronoi cell centroid on the plane is also the origin of the parameterized coordinates. The biased control point can be expressed as:

[0077] x=tx i ,y=ty i

[0078] Specifically, t is:

[0079]

[0080] Among them, A j is the area of ​​the jth Voronoi cell, A Bj is the area of ​​the closed B-spline corresponding to the j-th Voronoi cell. In this example, t is 0.65;

[0081] S33, performing a Boolean difference operation between the biased closed B-spline model and the initial protective gear model to obtain a porous protective gear model with a target porosity based on the temperature field.

[0082] The present invention realizes the design of personalized porous protective gear driven by the skin temperature field, effectively improves the thermal comfort and adaptability of wearing, and realizes the personalized customization function. Personalized porous protective gear based on the skin temperature field of the affected limb can be customized according to the affected limb of different patients, protecting the affected limb while improving the patient's wearing experience.

[0083] Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field and related fields without making creative efforts should fall within the scope of protection of the present invention. Structures, devices, and operating methods not specifically described and explained in the present invention shall be implemented in accordance with conventional means in the field unless otherwise specified or limited.

Claims

1. A personalized porous protective gear design method based on skin temperature field drive, characterized in that: The following steps are involved: S1. First, use a 3D scanner to scan the affected limb and construct an initial model of the protective gear. Design and 3D print porous protective gear with different porosities. Use an infrared thermal imaging scanner to extract the skin surface temperature data of the affected limb after wearing it to construct a temperature field. Then, using the Boltzmann radiation law and the formula for calculating the radiation heat transfer between the human body and the indoor environment, construct a mapping relationship model between the "skin temperature field and structural porosity"; S2. According to a proposed weighted random sampling method based on the isothermal surface area, the multi-pore positions and distributions matching the temperature field at the macro level are obtained and used as Voronoi sites to construct the geodesic Voronoi map; S3. Based on the obtained geodesic Voronoi diagram, closed geodesic B-splines are used to precisely control the cell size at the microscopic level. After normal bias, Boolean operations are performed with the initial protective gear model to obtain a personalized porous protective gear model with the target porosity.

2. The method for designing personalized porous protective gear based on skin temperature field drive according to claim 1, characterized in that: The S1 specifically includes the following steps: S11. First, use the Go!SCAN SPAPK™ portable 3D scanner to obtain 3D point cloud data of the affected limb and reconstruct the model. Then use the HIKMICRO-H11 infrared thermal imaging scanner from Hikvision to extract the surface temperature distribution data of the affected limb wearing protective gear with different porosities, and obtain the temperature field of the affected limb skin. S12. Based on the Boltzmann radiation law, the total power Qr is: Where ε is the emissivity, σ is the Stefan-Boltzmann coefficient, and the blackbody is 5.67*10 -8 watt / m 2 K 4 , S is the effective radiation area, obtained according to the DuBois formula, Trel is the average temperature of the actual state, and T0 is the average temperature of the initial state. The total heat exchange power Qr between the human body and the indoor environment is: Where S' is the effective radiation area when wearing protective gear, and the porosity and weight coefficient need to be considered, and S' = ω y ·f eff S, where ω y is the porosity weight function, fcl is the clothing area coefficient, that is, the ratio of the total surface area of ​​the human body after clothing to the naked area. It is 1 when naked. Wearing protective gear does not change the total surface area of ​​the external body, so fcl is 1 in this case. feff is the effective radiation area coefficient of the human body, which is the ratio of the effective radiation area S to the total surface area S0, that is, the porosity. Teff is the average skin temperature in the state of wearing protective gear, and T0 is the average skin temperature in the natural state. S13. Convert the Boltzmann radiation law and the radiation heat transfer formula between the human body and the indoor environment. The corresponding "temperature field T and porosity feff" relationship function model is: Among them, the empirical formula of porosity weight function ω is obtained by fitting the printed different porosity models with the corresponding infrared thermal imaging experimental results. y for: oh y =16151.26f eff 4 -26985.2f eff 3 +16730.07f eff 2 -4599.88f eff +484.

53.

3. The method for designing personalized porous protective gear based on skin temperature field drive according to claim 1, characterized in that: The S2 comprises the following steps: S21. Using the skin surface temperature field data of the affected limb, extract the isothermal surfaces and calculate the area of ​​each isothermal surface. Based on the proportion of each isothermal surface area to the total area, perform random sampling of multiple holes on the corresponding isothermal surface. The sampling probability density calculation formula for each isothermal surface is as follows: Where M is the number of isothermal surfaces, A i is the area of ​​the ith isothermal surface, A total is the total area of ​​the isothermal surface; S22. Perform proportional weighted random sampling in each isothermal surface area according to the corresponding sampling probability to obtain the multi-pore positions and distributions that conform to the temperature field distribution in a macroscopic manner, and use them as Voronoi sites to generate a geodesic Voronoi map.

4. The method for designing personalized porous protective gear based on skin temperature field drive according to claim 1, characterized in that: The S3 includes the following steps: S31. Based on the generated geodesic Voronoi diagram, a closed geodesic B-spline curve is generated on a geodesic polar coordinate parameterized two-dimensional plane. The B-spline point formula of the parameterized plane is as follows: Among them, N j，k (u) is the basis function of geodesic B-spline, P j are the control vertices of the geodesic B-spline, and u is the node parameter. Precisely control the cell size at the micro level to achieve the effect of regulating the porosity of the structure; S32. The obtained spline curve is normal-biased and then subjected to a Boolean difference operation with the initial protective gear model to obtain a porous protective gear model with a target porosity driven by the skin temperature field.

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