A method and system for 3D sizing of a prosthesis

Abstract

The present application relates to the field of visual measurement, in particular to a kind of 3D size measurement method and system of artificial limb.The present application, by collecting the structured light point cloud data of residual limb in natural relaxation, load bearing and standard position and other various states, constructs residual limb multi-state coordinate matching set and calculates residual limb coordinate displacement consistency parameter and other technical means, realizes the accurate quantification and scientific classification of the dynamic deformation amplitude of each area of residual limb surface.Based on displacement consistency and size fluctuation characteristics, the scheme further finely divides the three-dimensional space model into stable size area, easily deformable size area, basic fitting area and elastic accommodation area, and assigns specific size calculation rules to different areas, which plays the role of reserving sufficient gap for muscle swelling, providing buffer for skeletal protruding parts, and ensuring that the artificial limb still maintains stable suspension and gripping force when the volume changes dramatically, and generates measurement results that highly match the real biomechanical dynamic characteristics of patients.

Description

Technical Field

[0001] This invention relates to the field of visual measurement technology, and in particular to a method and system for measuring the dimensions of a prosthesis in 3D. Background Technology

[0002] The field of visual measurement technology mainly involves the science and technology of acquiring image information of target objects through optical imaging equipment and extracting information such as the geometric dimensions and spatial position of target features by combining image processing and computer vision technology. Its main purpose is to acquire the three-dimensional shape and size information of target objects in a non-contact manner.

[0003] Among them, the 3D size measurement method for prostheses refers to the specific operation process and evaluation method for obtaining the three-dimensional spatial geometric dimensions of the prosthetic device required by the patient. It is mainly used to obtain the contour features of the prosthesis surface and the specific size parameters of each part in order to facilitate subsequent fitting and manufacturing.

[0004] Traditional 3D measurement methods for prostheses can obtain the basic contour features of the prosthesis surface and provide the conventional dimensional parameters required for subsequent processing and manufacturing. However, when the patient is in different movement postures or is subjected to external physical loads, the subcutaneous fat and muscle tissue on the surface of the residual limb will undergo complex non-rigid deformation and volume expansion. There is a problem that single static three-dimensional spatial measurement data cannot truly reflect the dynamic geometric changes of the residual limb. As a result, the prosthesis socket is prone to friction slippage, local bone compression causing pain, and uneven overall force when actually worn. Summary of the Invention

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a method for measuring the dimensions of a prosthesis in 3D, comprising the following steps: S1: Collect structured light point clouds of the same residual limb under each preset state, construct a multi-state coordinate matching set of the residual limb, and calculate the coordinate displacement consistency parameter of the residual limb under the multi-state coordinate matching set of the residual limb. S2: Determine the basic contour of the prosthesis socket based on the residual limb coordinate displacement consistency parameter, and extract the reserved gap of the prosthesis socket from the basic contour data of the prosthesis socket; S3: Based on the multi-state coordinate matching set of the residual limb, determine the fluctuation range of the perimeter of the residual limb and the fluctuation range of the anterior-posterior diameter of the residual limb; S4: Mark the basic fitting area of ​​the prosthesis socket according to the fluctuation range of the residual limb circumference, and generate the corresponding basic fitting size data of the prosthesis socket; S5: Mark the elastic clearance area of ​​the prosthesis socket according to the fluctuation range of the anterior and posterior diameter of the residual limb, and generate the elastic clearance size data of the prosthesis socket. Combine the data with the basic contour of the prosthesis socket, the reserved gap of the prosthesis socket, and the basic fitting size data of the prosthesis socket to generate the 3D size measurement result of the prosthesis socket.

[0006] As a further aspect of the present invention, the residual limb coordinate displacement consistency parameter is specifically calculated by the coordinate displacement deviation value; the reserved gap of the prosthesis socket includes the easily deformable size area of ​​the residual limb and the alignment coordinate point; the fluctuation range of the residual limb circumference is specifically calculated by the deviation value between the upper limit value and the lower limit value of the residual limb circumference measurement; the fluctuation range of the residual limb anteroposterior diameter is specifically calculated by the deviation value between the upper limit value and the lower limit value of the residual limb anteroposterior diameter measurement; the basic fitting size data of the prosthesis socket includes the residual limb annular area, the basic fitting area of ​​the prosthesis socket, and the fixed size measurement rules; and the elastic clearance size data of the prosthesis socket includes the residual limb local area, the elastic clearance area of ​​the prosthesis socket, and the reserved size measurement rules.

[0007] As a further aspect of the present invention, step S1 specifically comprises: S101: Collect the structured light point cloud of the same limb under various preset states, including the natural relaxation state, the load-bearing state, and the standard positioning state. Integrate the structured light point cloud of the limb under each state into multiple sets of three-dimensional surface point sets of the limb. Calculate the displacement change between the corresponding three-dimensional surface point sets of the limb under each state to obtain the non-rigid displacement field of the limb. S102: Extract the coordinate offset of each three-dimensional coordinate point from the non-rigid displacement field of the residual limb, calculate the coordinate offset and the coordinate sum between the corresponding three-dimensional coordinate points in the three-dimensional surface point set of the residual limb, and generate aligned coordinate points; S103: Integrate each of the aligned coordinate points belonging to the same anatomical region of the residual limb, establish a multi-state coordinate matching set of the residual limb, calculate the coordinate displacement deviation value of each of the aligned coordinate points within the anatomical region of the residual limb in the multi-state coordinate matching set of the residual limb, and obtain the coordinate displacement consistency parameter of the residual limb.

[0008] As a further aspect of the present invention, step S2 specifically comprises: S201: Compare the residual limb coordinate displacement consistency parameter with the preset soft tissue displacement judgment threshold one by one, and determine the corresponding residual limb anatomical area where the residual limb coordinate displacement consistency parameter of all the aligned coordinate points is lower than the soft tissue displacement judgment threshold, and divide it into the residual limb stable size area. S202: Extract the alignment coordinate points corresponding to the stable size region of the residual limb from the multi-state coordinate matching set of the residual limb, and establish the basic contour of the prosthesis socket. S203: The anatomical region of the residual limb corresponding to the residual limb coordinate displacement consistency parameter being higher than the soft tissue displacement judgment threshold is divided into the residual limb easily deformable size region. The corresponding alignment coordinate points belonging to the residual limb easily deformable size region are extracted from the residual limb multi-state coordinate matching set to generate the reserved gap of the prosthesis socket.

[0009] As a further aspect of the present invention, step S3 specifically comprises: S301: Based on the multi-state coordinate matching set of the residual limb, for the same residual limb anatomical region in the stable size region and the easily deformable size region of the residual limb, calculate the residual limb perimeter measurement value and residual limb anterior-posterior diameter measurement value in the same residual limb anatomical region under multiple states in the same residual limb anatomical region; S302: Based on the measured values ​​of the residual limb circumference and the measured values ​​of the residual limb anteroposterior diameter, determine the upper limit value and the lower limit value of the residual limb circumference measurement under multiple states, as well as the upper limit value and the lower limit value of the residual limb anteroposterior diameter measurement under multiple states. S303: Calculate the deviation between the upper limit and lower limit of the residual limb circumference measurement to generate the residual limb circumference fluctuation range; calculate the deviation between the upper limit and lower limit of the residual limb anteroposterior diameter measurement to generate the residual limb anteroposterior diameter fluctuation range.

[0010] As a further aspect of the present invention, step S4 specifically comprises: S401: Obtain the basic fit upper limit threshold corresponding to the prosthesis socket, and extract the circumference fluctuation value of the residual limb annular region within the residual limb anatomical area by referring to the fluctuation range of the residual limb circumference. S402: Select the residual limb ring area where the circumference fluctuation value is lower than the basic fit upper limit threshold, and mark it as the basic fit area of ​​the prosthesis socket; S403: Assign fixed size measurement rules to the basic fitting area of ​​the prosthesis socket, and calculate the basic fitting size data of the prosthesis socket.

[0011] As a further aspect of the present invention, step S5 specifically comprises: S501: Obtain the lower limit threshold of elasticity clearance corresponding to the prosthesis socket, and extract the anteroposterior diameter fluctuation value corresponding to the local area of ​​the residual limb within the anatomical area of ​​the residual limb, referring to the fluctuation range of the anteroposterior diameter of the residual limb. S502: Select the local area of ​​the residual limb corresponding to the anteroposterior diameter fluctuation value being higher than the lower limit threshold of elasticity, mark it as the elasticity allowance area of ​​the prosthesis socket, allocate reserved size measurement rules for the elasticity allowance area of ​​the prosthesis socket, and calculate the elasticity allowance size data of the prosthesis socket; S503: Combine the basic contour of the prosthesis socket, the data on the fit between the reserved gap of the prosthesis socket and the basic dimensions of the prosthesis socket, and the data on the elastic clearance dimensions of the prosthesis socket to obtain the 3D dimension measurement result of the prosthesis socket.

[0012] A 3D dimensional measurement system for prostheses, comprising: The consistency calculation module collects structured light point clouds of the same limb under each preset state, constructs a multi-state coordinate matching set of the limb, and calculates the coordinate displacement consistency parameters of the limb under the multi-state coordinate matching set of the limb. The gap extraction module determines the basic contour of the prosthesis socket based on the residual limb coordinate displacement consistency parameters and extracts the reserved gap of the prosthesis socket from the basic contour data of the prosthesis socket. The range determination module determines the fluctuation range of the perimeter of the residual limb and the fluctuation range of the anteroposterior diameter of the residual limb based on the multi-state coordinate matching set of the residual limb. The size data generation module marks the basic fitting area of ​​the prosthesis socket with reference to the fluctuation range of the residual limb circumference size, and generates the corresponding basic fitting size data of the prosthesis socket. The measurement result determination module marks the elastic clearance area of ​​the prosthesis socket with reference to the fluctuation range of the anterior and posterior diameter of the residual limb, and generates elastic clearance size data of the prosthesis socket. This data is then combined with the basic contour of the prosthesis socket, the reserved gap of the prosthesis socket, and the basic fitting size data of the prosthesis socket to generate 3D size measurement results of the prosthesis socket.

[0013] Compared with the prior art, the advantages and positive effects of the present invention are as follows: In this invention, structured light point cloud data of the residual limb under various states, including natural relaxation, load-bearing, and standard positioning, is collected. This is followed by the construction of a multi-state coordinate matching set for the residual limb and the calculation of coordinate displacement consistency parameters. These techniques enable precise quantification and scientific classification of the dynamic deformation amplitude of different regions on the residual limb surface. Based on displacement consistency and dimensional fluctuation characteristics, this solution further refines the three-dimensional spatial model into stable dimension regions, easily deformable dimension regions, basic fit regions, and elastic clearance regions. Specific dimensional calculation rules are assigned to different regions, providing sufficient clearance for muscle expansion, buffering and avoiding protruding bone areas, and ensuring that the prosthesis maintains stable suspension and gripping force even during drastic volume changes. Ultimately, this results in a 3D dimensional measurement of the prosthesis socket that highly matches the patient's actual biomechanical dynamic characteristics. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a schematic diagram of the steps of the present invention; Figure 2 This is a detailed schematic diagram of S1 of the present invention; Figure 3 This is a detailed schematic diagram of S2 of the present invention; Figure 4 This is a detailed schematic diagram of S3 of the present invention; Figure 5 This is a detailed schematic diagram of S4 of the present invention; Figure 6 This is a detailed schematic diagram of S5 of the present invention; Figure 7 This is a system module diagram of the present invention. Detailed Implementation

[0016] The technical solution of the present invention will now be described with reference to the accompanying drawings.

[0017] Please see Figure 1 This invention provides a method for measuring the 3D dimensions of a prosthesis, comprising the following steps: S1: Collect structured light point clouds of the same residual limb under each preset state, construct a multi-state coordinate matching set of the residual limb, and calculate the coordinate displacement consistency parameter of the residual limb under the multi-state coordinate matching set of the residual limb. S2: Determine the basic contour of the prosthesis socket based on the residual limb coordinate displacement consistency parameter, and extract the reserved gap of the prosthesis socket from the basic contour data of the prosthesis socket; S3: Based on the multi-state coordinate matching set of the residual limb, determine the fluctuation range of the perimeter and the fluctuation range of the anteroposterior diameter of the residual limb; S4: Mark the basic fitting area of ​​the prosthesis socket according to the fluctuation range of the residual limb circumference, and generate the corresponding basic fitting size data of the prosthesis socket; S5: Mark the elastic clearance area of ​​the prosthesis socket according to the fluctuation range of the anterior and posterior diameter of the residual limb, and generate the elastic clearance size data of the prosthesis socket. Combine it with the basic contour of the prosthesis socket, the reserved gap of the prosthesis socket and the basic fitting size data of the prosthesis socket to generate the 3D size measurement result of the prosthesis socket.

[0018] The stump coordinate displacement consistency parameter is specifically calculated by the coordinate displacement deviation value. The reserved gap of the prosthesis socket includes the easily deformable size area of ​​the stump and the alignment coordinate point. The stump circumference fluctuation range is specifically calculated by the deviation value between the upper limit value and the lower limit value of the stump circumference measurement. The stump anteroposterior diameter fluctuation range is specifically calculated by the deviation value between the upper limit value and the lower limit value of the stump anteroposterior diameter measurement. The basic fitting size data of the prosthesis socket includes the stump annular area, the basic fitting area of ​​the prosthesis socket, and the fixed size measurement rules. The elastic clearance size data of the prosthesis socket includes the local area of ​​the stump, the elastic clearance area of ​​the prosthesis socket, and the reserved size measurement rules.

[0019] Please see Figure 2 Step S1 is as follows: S101: Collect the structured light point cloud of the same limb under various preset states, including the natural relaxation state, the load-bearing state, and the standard positioning state. Integrate the structured light point cloud of the limb under each state into multiple sets of three-dimensional surface point sets of the limb. Calculate the displacement change between the corresponding three-dimensional surface point sets of the limb under each state to obtain the non-rigid displacement field of the limb. The first structured light point cloud of the residual limb in a naturally relaxed state was acquired using visual measurement technology. Visual measurement represents a digital engineering method that uses optical imaging principles combined with non-contact sensors to extract the three-dimensional spatial coordinates of the target object's surface morphology with high precision. The naturally relaxed state indicates that the amputation site is not subject to any external physical pressure, and the internal muscle tissue is in a completely non-contractile resting physiological state. The structured light point cloud represents a dense set of three-dimensional spatial coordinates resolved by projecting a specifically coded grating pattern onto the surface of the amputation site and capturing the grating deformation with an optical lens. A vertical pressure of 400 Newtons was applied downwards to the amputation site to simulate the weight distribution of a standing human body, thus entering a weight-bearing state. The optical lens was activated again to acquire the second structured light point cloud of the residual limb in the weight-bearing state using visual measurement. The amputation site was adjusted to a sitting posture, with the joints bent to a strict 45-degree angle, entering a standard positioning state. A third optical scan was performed to acquire the third structured light point cloud of the residual limb in the standard positioning state. All spatial coordinates from the first, second, and third structured light point clouds were extracted to construct corresponding 3D surface point sets for the first, second, and third residual limbs. The lateral, longitudinal, and depth coordinates of the corresponding reference positions were extracted from these three residual limb 3D surface point sets. The lateral, longitudinal, and depth coordinate differences at specific reference positions were calculated by subtracting the corresponding coordinate values ​​of the first residual limb 3D surface point set from the coordinate values ​​of the second residual limb 3D surface set. All coordinate differences at specific reference positions were recorded, and outlier values ​​were removed. Five hundred historical patient scan calibration log files were obtained, and the movement distance values ​​of all adjacent scan points in the calibration log files were extracted. The arithmetic mean and standard deviation of all movement distance values ​​were calculated. The standard deviation was multiplied by 3 and then added to the arithmetic mean to obtain an upper limit of 0.5 mm for outlier detection. The outlier threshold of 0.5 mm represents the maximum physical limit of traction deformation in adjacent, extremely small regions of skin tissue under normal physiological conditions. The Euclidean distance between a specific reference location and its neighboring points is calculated. If the Euclidean distance is greater than 0.5 mm, it indicates noise caused by reflected light from the visual measurement device, and all data for that reference location are deleted. If the Euclidean distance is equal to 0.5 mm, it indicates the reference location is at the absolute critical point of physiological deformation, and it is marked as pending verification. If the Euclidean distance is less than 0.5 mm, it indicates the reference location conforms to normal biomechanical deformation patterns, and its data is retained.The lateral coordinate differences, longitudinal coordinate differences, and depth coordinate differences of all the retained specific reference positions are combined to finally generate the non-rigid displacement field of the residual limb.

[0020] S102: Extract the coordinate offset of each three-dimensional coordinate point from the non-rigid displacement field of the residual limb, calculate the coordinate offset and the coordinate sum between the corresponding three-dimensional coordinate points in the three-dimensional surface point set of the residual limb, and generate aligned coordinate points; The lateral, longitudinal, and depth coordinate differences corresponding to each specific reference position are extracted from the non-rigid displacement field of the stump. The non-rigid displacement field of the stump represents a data matrix recording the non-fixed spatial displacement distances of all points on the surface of the amputation site when transitioning between different physical force states. The extracted differences are uniformly named the coordinate offsets corresponding to each three-dimensional coordinate point in the three-dimensional surface point set of the stump. The original lateral, longitudinal, and depth coordinate values ​​of specific reference positions in the first stump three-dimensional surface point set are extracted. These original coordinate values ​​are added to the corresponding lateral, longitudinal, and depth coordinate offsets to calculate new lateral, longitudinal, and depth coordinate values. Before outputting the new coordinate values ​​in each direction, the coordinate offsets need to be validated for safety. Extreme values ​​of skin elasticity stretching under a stretching tester are collected from multiple amputees, recording the maximum stretching displacement value before tissue tearing. The arithmetic mean and standard deviation of all maximum stretching displacement values ​​are calculated. Multiplying the standard deviation by 2 and summing it with the arithmetic mean yields the upper limit of coordinate offset, 21.0 mm. This upper limit represents the maximum absolute displacement that the skin of the lower limbs can undergo without causing physical damage. The absolute values ​​of the lateral, longitudinal, and depth coordinate offsets are calculated separately. If the absolute value of any coordinate offset is greater than 21.0 mm, it indicates that the offset exceeds the safe physiological limit of human tissue stretching, and the absolute value of that offset is forcibly changed to 21.0 mm. If the absolute value of any coordinate offset is equal to 21.0 mm, it indicates that the offset has just reached the safe physiological limit, and the original coordinate offset value is retained, with a warning record written to the log file. If the absolute value of any coordinate offset is less than 21.0 mm, it indicates that the offset is within a safe and reasonable physiological range, and the original coordinate offset value is directly retained. After successful verification, the new coordinate values ​​obtained from the addition operation are merged into a complete spatial coordinate point, and finally, the complete spatial coordinate point is generated as the aligned coordinate point.

[0021] S103: Integrate each aligned coordinate point belonging to the same anatomical region of the residual limb, establish a multi-state coordinate matching set of the residual limb, calculate the coordinate displacement deviation value of each aligned coordinate point in the anatomical region of the residual limb multi-state coordinate matching set, and obtain the coordinate displacement consistency parameter of the residual limb. All generated alignment coordinate points are read, and their specific locations on the amputation site are determined based on human anatomical atlases. Alignment coordinate points belonging to different anatomical locations, such as the patellar ligament region, anterior tibial crest region, and fibular head region, are stored separately. Alignment coordinate points belonging to the same anatomical region in all relaxed, weight-bearing, and standard positioning states are correlated to establish a multi-state coordinate matching set for the residual limb. This set represents a data repository summarizing all relevant spatial coordinate changes under different stress conditions for the same anatomical physiological structure. The three-dimensional spatial coordinates of a specific reference position in the multi-state coordinate matching set are extracted in the relaxed, weight-bearing, and standard positioning states. The Euclidean distance between the two states is calculated by calculating the sum of squares of the differences in lateral, longitudinal, and depth coordinates between the relaxed and weight-bearing states, and then taking the positive square root of the sum. This distance is defined as the first state interval. Similarly, by calculating the sum of squares of the spatial coordinate differences and taking the positive square root, the Euclidean distance between the relaxed state and the standard positioning state is obtained, defined as the second state spacing; the Euclidean distance between the load-bearing state and the standard positioning state is obtained, defined as the third state spacing. The first, second, and third state spacings are summed, and the sum is divided by the total number of state spacings to obtain the arithmetic mean. This arithmetic mean is defined as the coordinate displacement deviation value of a specific reference position. The coordinate displacement deviation values ​​of all specific reference positions within a specific anatomical region are extracted, and the overall arithmetic mean of these values ​​is calculated. By calculating the square of the difference between each coordinate displacement deviation value and the overall arithmetic mean, all squared results are summed, and then divided by the total number of values ​​to obtain the variance value. This variance value is established as the residual limb coordinate displacement consistency parameter. Finally, the residual limb coordinate displacement consistency parameter for this region is output.

[0022] Please see Figure 3 Step S2 is as follows: S201: Compare the residual limb coordinate displacement consistency parameter with the preset soft tissue displacement judgment threshold one by one, and determine the corresponding residual limb anatomical area where the residual limb coordinate displacement consistency parameter of all aligned coordinate points is lower than the soft tissue displacement judgment threshold, and classify it as the residual limb stable size area.

[0023] Tissue stability refers to the ability of the internal skeletal support to resist the outward diffusion and movement of soft tissue in a localized area on the surface of the amputation site under external pressure. Three-dimensional motion capture tracking data of various lower limb parts from 200 healthy adults during walking and running were collected. The spatial displacement variance values ​​of all surface tracking points in the motion capture tracking data were extracted. All surface tracking point spatial displacement variance values ​​were sorted in ascending order. The median variance value, located exactly in the middle of the sorted values, was selected; the median variance value was calculated to be 0.0050 square millimeters. This median variance value of 0.0050 square millimeters was established as the preset soft tissue displacement judgment threshold. The preset soft tissue displacement judgment threshold of 0.0050 square millimeters represents a strict mathematical boundary between the surface area directly supported by rigid bone and the easily movable surface area rich in fat and muscle. The calculated residual limb coordinate displacement consistency parameters corresponding to specific anatomical regions were retrieved. The residual limb coordinate displacement consistency parameters were compared with the preset soft tissue displacement judgment threshold of 0.0050 square millimeters. If the stump coordinate displacement consistency parameter is greater than the preset soft tissue displacement judgment threshold, it indicates that the fat or muscle tissue beneath the current anatomical area is relatively thick, making it prone to sliding deformation under pressure and thus not meeting the stability condition. Therefore, the current anatomical area is excluded. If the stump coordinate displacement consistency parameter is equal to the preset soft tissue displacement judgment threshold, it indicates that the current anatomical area is at the transitional edge between skeletal support and free soft tissue. To maximize the load-bearing area, the current anatomical area equal to this threshold is also considered to meet the stability condition and marked as a usable area. If the stump coordinate displacement consistency parameter is less than the preset soft tissue displacement judgment threshold, it indicates that the area has solid bone structure support beneath it, and its shape changes extremely little under pressure. Therefore, it is judged to meet the stability condition and marked as a usable area. The above numerical comparison process is repeated for all anatomical areas. The spatial boundary coordinates of all anatomical areas marked as usable areas are extracted. A boundary fusion algorithm is used to stitch together the spatial boundary coordinates of adjacent areas marked as usable areas and eliminate internal overlapping contour lines. The one or more complete and continuous large-area geometric intervals formed after stitching are ultimately divided into stump stable size zones. The stable size zone of the stump constitutes the core rigid load-bearing foundation when making the prosthesis socket.

[0024] S202: Extract the aligned coordinate points corresponding to the stable size region of the residual limb from the multi-state coordinate matching set of the residual limb, and establish the basic contour of the prosthesis socket. A data retrieval command is sent to a database storing a set of multi-state coordinate matching sets of residual limbs. Based on the received spatial boundary coordinate range, the database filters out all aligned coordinate points whose horizontal, vertical, and depth coordinates fall completely within the spatial boundary coordinate range and extracts them all. For the tens of thousands of extracted aligned coordinate points, a Delaunay triangulation operation is performed. Delaunay triangulation is a geometric process that connects discrete spatial coordinate points into non-intersecting triangular faces. Specifically, three adjacent aligned coordinate points are arbitrarily selected, and the center coordinates and radius of the circumcircle formed by these three points are calculated. If all other aligned coordinate points are not inside this circumcircle, these three aligned coordinate points are connected to form a valid triangular facet. This operation is performed on all extracted aligned coordinate points, generating a massive number of triangular facets. These triangular facets are then pieced together to form a complete 3D curved surface shell. To eliminate sharp protrusions on the surface of the 3D curved surface shell, surface smoothing calculations are required. The coordinates of the three vertices of each triangular facet are extracted, and the cross product of the two edge vectors is calculated to obtain the normal vector of the triangular facet. The arithmetic mean of the normal vectors of all adjacent triangular faces is calculated to obtain the vertex normal vector. Along the direction of the vertex normal vector, the vertex coordinates are moved inward or outward by a minimal distance, making the angles between adjacent triangular faces gentler. The 3D curved surface shell, after surface smoothing calculations, perfectly conforms to the hard, undeformable skin surface of the amputation site. This surface-smoothed 3D curved surface shell is ultimately used to establish the basic contour of the prosthetic socket.

[0025] S203: The residual limb anatomical region corresponding to the residual limb coordinate displacement consistency parameter being higher than the soft tissue displacement judgment threshold is divided into the residual limb easily deformable size region. The alignment coordinate points corresponding to the residual limb easily deformable size region are extracted from the residual limb multi-state coordinate matching set to generate the reserved gap of the prosthesis socket. The comparison log of the stump coordinate displacement consistency parameter and the preset soft tissue displacement judgment threshold was retrieved. From the comparison log, anatomical regions whose comparison results showed that the stump coordinate displacement consistency parameter was greater than the preset soft tissue displacement judgment threshold were specifically extracted. The boundary coordinates of these extracted anatomical regions were merged. The resulting geometric range was uniformly divided into the stump deformable size zone. The stump deformable size zone represents the area on the amputation site covered by abundant calf abdominal muscles or subcutaneous fat, which will undergo significant volume expansion and displacement when walking with a prosthesis. Based on the boundary coordinates of the stump deformable size zone, all aligned coordinate points belonging to its interior were extracted from the stump multi-state coordinate matching set. To leave sufficient physical space for muscle expansion, the expansion amount needs to be calculated. Intracavitary pressure sensor monitoring values ​​were collected from 150 amputees when trying on prostheses of different sizes. The internal volume of the prosthesis corresponding to the lowest intracavitary pressure value when the patient reported no pressure pain was extracted. This volume was divided by the volume of the patient's original amputation site to calculate the volume expansion ratio. The arithmetic mean of the volume expansion ratios of all patients is calculated to obtain a preset expansion coefficient of 1.15. This preset expansion coefficient of 1.15 represents the additional space expansion multiplier required by deformable soft tissue to ensure unobstructed blood circulation. The coordinate displacement deviation of a specific reference position within the deformable size area of ​​the residual limb is extracted and multiplied by the preset expansion coefficient of 1.15 to calculate the spatial expansion distance. The vertical outward normal vector of the surface at this specific reference position is calculated. The specific reference position is translated outward along the direction of the vertical outward normal vector by the calculated spatial expansion distance, generating a new outward expansion coordinate point. For each aligned coordinate point within this area, the calculation of multiplying by the preset expansion coefficient and translating along the normal is performed to generate an outward expansion three-dimensional surface composed of all outward expansion coordinate points. The volume difference of the sealed space between the outward expansion three-dimensional surface and the original three-dimensional surface of the deformable size area of ​​the residual limb is calculated. The calculated volume difference of the sealed space is ultimately used to generate the reserved gap for the prosthesis socket.

[0026] Please see Figure 4 Step S3 is as follows: S301: Based on the multi-state coordinate matching set of the residual limb, for the same residual limb anatomical region in the stable size region and the easily deformable size region of the residual limb, calculate the measurement values ​​of the perimeter and the anteroposterior diameter of the residual limb in multiple states in the same residual limb anatomical region. Extract the anatomical region label sets contained in the stable size region and the deformable size region of the residual limb. Compare and find the intersecting anatomical region labels that exist simultaneously in the two sets. Designate the physical space corresponding to the intersecting anatomical region labels as the same residual limb anatomical region. Between the highest and lowest point coordinates of the same residual limb anatomical region, set a horizontal intercept plane every 2.0 mm along the depth coordinate axis. Select the horizontal intercept plane at a specific depth coordinate. Extract all aligned coordinate points that intersect with this horizontal intercept plane in the natural relaxation state. Sort all the intersecting aligned coordinate points end to end according to the polar coordinate angle from smallest to largest, forming a completely closed contour polygon. Extract two adjacent aligned coordinate points on the closed contour polygon, calculate the square of the difference between the horizontal coordinates and the square of the difference between the vertical coordinates of the two points respectively, sum them and calculate the positive square root to obtain the straight-line distance between the two adjacent points. Calculate the straight-line distances of all adjacent aligned coordinate points on the polygon and sum all the straight-line distances. Establish the total length obtained by the summation as the measured value of the residual limb perimeter of the current section in the natural relaxation state. The coordinates of the foremost point with the largest longitudinal coordinate value and the coordinates of the rearmost point with the smallest longitudinal coordinate value are extracted from the closed contour polygon. The straight-line distance between these two points is obtained by calculating the difference in their longitudinal coordinates, and this straight-line distance is established as the measurement value of the anteroposterior diameter of the residual limb in the natural relaxed state. For the load-bearing state and the standard positioning state, the above calculations of polygon connection, summation of straight-line distances, and subtraction of extreme coordinate points are completely repeated. Finally, the perimeter and anteroposterior diameter measurements of the residual limb are calculated for all three states of the horizontal cutting plane.

[0027] S302: Based on the measured values ​​of the circumference and anteroposterior diameter of the residual limb, determine the upper limit and lower limit values ​​of the circumference measurement of the residual limb under various conditions, as well as the upper limit and lower limit values ​​of the anteroposterior diameter measurement of the residual limb under various conditions. Extract all residual limb perimeter measurements from a specific horizontal section. Compare the residual limb perimeter measurements in the relaxed, loaded, and standard positions. If the value in the first position is greater than both the value in the second and third positions, the value in the first position is the maximum value. If the value in the second position is greater than both the value in the first and third positions, the comparison condition is met, and the value in the second position is extracted. If the value in the third position is greater than the other two values, it is the maximum value. Establish the extracted maximum value as the upper limit value for residual limb perimeter measurements across all positions. Use the same comparison logic to find the minimum value. If the value in a certain position is less than the values ​​in the other two positions, the comparison condition is met, and this value is extracted and established as the lower limit value for residual limb perimeter measurements across all positions. Similarly, extract all residual anteroposterior diameter measurements from this section and compare the anteroposterior diameter values ​​in each of the three positions. If a value is greater than the other two values, extract it and establish it as the upper limit value for residual anteroposterior diameter measurements across all positions. If a value is less than the other two values, extract it and establish it as the lower limit value for residual anteroposterior diameter measurements across all positions. Complete the process of determining the upper and lower limits of the values.

[0028] S303: Calculate the deviation between the upper limit value and the lower limit value of the residual limb circumference measurement, generate the residual limb circumference size fluctuation range, and calculate the deviation between the upper limit value and the lower limit value of the residual limb anteroposterior diameter measurement, generate the residual limb anteroposterior diameter size fluctuation range. The upper limit of the residual limb circumference measurement represents the outermost contour length that a cross-section at a specific height can achieve when the amputated site is subjected to the maximum external physical load, causing extreme muscle congestion and expansion. The lower limit of the residual limb circumference measurement represents the most basic contour length of a cross-section at a specific height when the amputated site is completely relaxed and not subjected to any external pressure. A subtraction operation is performed, using the upper limit of the residual limb circumference measurement as the minuend and the lower limit as the subtrahend. By subtracting the subtrahend from the minuend, the corresponding deviation value of the residual limb circumference is calculated. This calculated deviation value is directly established and generated as the dimensional fluctuation range of the residual limb circumference at the current horizontal cross-section. Next, the upper limit and lower limit of the anteroposterior diameter measurement of the residual limb are extracted from the horizontal cross-section. The upper limit of the anteroposterior diameter measurement represents the maximum straight-line span in the anteroposterior direction when the amputated site is in a specific movement posture, with the knee bent causing the anterior ligaments and posterior muscles to simultaneously taut and protrude outwards. The lower limit of the anteroposterior diameter measurement represents the minimum straight-line span in the anteroposterior direction when the amputated site is in a naturally hanging state. Perform a subtraction operation, subtracting the upper limit of the anteroposterior diameter measurement of the residual limb as the minuend and the lower limit as the subtrahend, to calculate the corresponding deviation value of the anteroposterior diameter of the residual limb. This deviation value is then directly established and generated as the dimensional fluctuation range of the anteroposterior diameter of the residual limb for the current horizontal section. This process is repeated across all horizontal sections, subtracting the subtrahend from the minuend, to calculate the fluctuation range data for each height section.

[0029] Please see Figure 5 Step S4 is as follows: S401: Obtain the basic fit upper limit threshold corresponding to the prosthesis socket, and extract the corresponding circumference fluctuation value of the residual limb annular region within the residual limb anatomical area by referring to the fluctuation range of the residual limb circumference. A prosthetic socket suspension pull-out mechanics experiment was conducted, in which 300 test prosthetic cavities with silicone liners were fitted onto experimental models. A constant weight of 50 Newtons was attached to the bottom of the prosthetic cavity. The perimeter of each horizontal cross-section inside the prosthetic cavity was progressively increased using a screw expansion mechanism. A laser displacement sensor was used to monitor the vertical displacement of the prosthetic cavity relative to the experimental model as it slipped downwards. When the laser displacement sensor detected a vertical downward slippage displacement exceeding 5.0 mm, the difference in perimeter caused by the expansion of the prosthetic cavity was recorded. The perimeter difference recorded at the moment of slippage in all 300 experiments was extracted. All perimeter differences were sorted from smallest to largest, and the median difference was extracted. The median difference was calculated to be 6.5 mm. This median difference of 6.5 mm was set as the upper limit threshold for the basic fit of the prosthetic socket. The basic fit upper limit threshold of 6.5 mm represents the ultimate physical boundary at which, when the perimeter of the amputation site changes beyond 6.5 mm, the friction between the prosthesis and the skin surface will drastically decrease, potentially leading to prosthesis fallout. Anatomical regions of the stump containing multiple horizontal sections are extracted, and regions forming a complete 360-degree closed loop across the entire height range are selected and defined as the stump annulus region. The perimeter fluctuation range of all horizontal sections within the stump annulus region is extracted. The perimeter fluctuation ranges of all sections within a specific stump annulus region are summed, and the arithmetic mean is calculated by dividing the sum by the number of sections. This arithmetic mean is used as the corresponding perimeter fluctuation value for the stump annulus region within the anatomical region of the stump. The unique identifier of the stump annulus region is then linked to the calculated perimeter fluctuation value for extraction.

[0030] S402: Select the residual limb annulus area where the circumference fluctuation value is lower than the upper limit threshold of the basic fit, and mark it as the basic fit area of ​​the prosthesis socket; The experimental baseline fit threshold of 6.5 mm was retrieved. The circumference fluctuation value of the residual limb annulus region was compared with the baseline fit threshold of 6.5 mm. If the circumference fluctuation value of the residual limb annulus region is greater than the baseline fit threshold of 6.5 mm, it indicates that the tissue volume of this area changes drastically under different movement states. If this area is used as the main friction force area, the prosthesis cavity will completely lose its suspension and gripping force when its volume decreases. Therefore, the condition is not met, and the data of the current residual limb annulus region is discarded. If the circumference fluctuation value of the residual limb annulus region is equal to the baseline fit threshold of 6.5 mm, it indicates that the volume change of this area is just at the critical risk point of prosthesis fall. For safety and stability considerations, the case of 6.5 mm is also judged as not meeting the condition, and the data of the current residual limb annulus region is discarded. If the circumference fluctuation value of the residual limb annulus region is less than the baseline fit threshold of 6.5 mm, it indicates that the tissue morphology of this area remains relatively constant whether standing or sitting, and can provide continuous and stable surface friction resistance to suspend the prosthesis. The comparison condition is met. Select the stump ring region where the judgment condition is met, and write the verification mark character into the database record row of that stump ring region. Extract all stump ring regions with verification mark characters, integrate and summarize them, and officially mark them as the basic fitting area of ​​the prosthesis socket. The basic fitting area of ​​the prosthesis socket is the most critical geometric zone in the entire prosthesis cavity responsible for tightly holding the stump and preventing dislodgement.

[0031] S403: Assign fixed-size measurement rules to the basic fitting area of ​​the prosthesis socket and calculate the basic fitting size data of the prosthesis socket; the fixed-size measurement rules are determined based on the upper limit value and the lower limit value of the residual limb circumference measurement corresponding to the basic fitting area of ​​the prosthesis socket. A predefined fixed-size measurement rule was assigned to the basic fitting area of ​​the prosthesis socket. This fixed-size measurement rule is a mathematical formula that calculates the optimal manufacturing size by assigning different multiplication coefficients to the limiting perimeter under different conditions. To determine the multiplication coefficients, subjective comfort scores were collected from 100 amputees wearing prostheses of different sizes and proportions, ranging from 1 to 10. Using the comfort score as the dependent variable and the lower and upper weight coefficients as independent variables, a multiple linear regression equation was established, with the lower and upper weight coefficients constrained to equal 1. The multiple linear regression equation was solved using the least squares method, determining that when the comfort score reaches its peak, the lower weight coefficient is 0.65 and the upper weight coefficient is 0.35. The lower weight coefficient of 0.65 was used as the preset lower weight factor, and the upper weight coefficient of 0.35 was used as the preset upper weight factor. The upper limit value of the residual limb perimeter measurement for a specific horizontal section of the basic fitting area of ​​the prosthesis socket was extracted, and the corresponding lower limit value of the residual limb perimeter measurement was also extracted. The system performs multiplication and addition operations as defined by the fixed-size measurement rules. The basic perimeter product is calculated by multiplying the lower limit of the residual limb perimeter measurement by a preset lower limit weighting factor of 0.65; the expansion perimeter product is calculated by multiplying the upper limit of the residual limb perimeter measurement by a preset upper limit weighting factor of 0.35. Finally, the basic perimeter product and the expansion perimeter product are summed to obtain the final perimeter value. This calculated final perimeter value is then formally generated and assigned to the prosthetic socket basic fitting dimension data. The prosthetic socket basic fitting dimension data represents the absolute physical perimeter dimension that the fitting area should possess during the final 3D printing or molding process.

[0032] Please see Figure 6 Step S5 is as follows: S501: Obtain the lower limit threshold of elasticity concession corresponding to the prosthesis socket, and extract the anteroposterior diameter fluctuation value of the local area of ​​the residual limb within the anatomical area of ​​the residual limb by referring to the fluctuation range of the anteroposterior diameter of the residual limb. Subcutaneous soft tissue thickness scans were performed on prominent lower limb skeletal structures such as the anterior tibial crest and fibular head in multiple amputees using a medical ultrasonic thickness gauge. The soft tissue thickness at the highest point of the bone protrusion and in a flat area 3.0 cm outside the protrusion were recorded. The thickness difference was calculated by subtracting the soft tissue thickness at the highest point of the bone from the thickness of the flat area. The arithmetic mean of the thickness differences for all amputees was calculated, yielding a mean of 3.8 mm. This arithmetic mean of 3.8 mm was established as the lower limit of elastic clearance for the prosthetic socket. This lower limit represents the minimum depth buffer distance that the amputation site must provide to accommodate sharp bone protrusions and prevent direct physical collision between the bone and the rigid prosthetic inner wall, which could lead to skin ulceration. The anteroposterior diameter fluctuation range of the residual limb was extracted from all horizontal cross-sections. Based on human anatomical atlases, specific independent areas that did not form a complete closed loop and existed only on the local surface within the anatomical region of the residual limb were identified and defined as the local area of ​​the residual limb. Locate a specific local region of the residual limb. Extract the anteroposterior diameter fluctuation range data of the residual limb corresponding to a specific anteroposterior diameter measurement section passing through this local region. Directly rename this anteroposterior diameter fluctuation range data and extract it as the anteroposterior diameter fluctuation value corresponding to this local region of the residual limb. Associate and save the coordinate boundary of the local region of the residual limb with this anteroposterior diameter fluctuation value.

[0033] S502: Select the local area of ​​the residual limb corresponding to the anteroposterior diameter fluctuation value being higher than the lower limit threshold of elasticity allowance, mark it as the elasticity allowance area of ​​the prosthesis socket, assign reserved size measurement rules to the elasticity allowance area of ​​the prosthesis socket, and calculate the elasticity allowance size data of the prosthesis socket; the size measurement rules are determined based on the upper limit value of the anteroposterior diameter measurement of the residual limb corresponding to the elasticity allowance area of ​​the prosthesis socket and the anteroposterior diameter fluctuation value; The experimentally set lower limit threshold for elasticity clearance is 3.8 mm. The anteroposterior diameter fluctuation value is compared with this threshold. If the fluctuation value is less than 3.8 mm, it indicates minimal bone protrusion in the affected area, sufficient soft tissue for cushioning, and no additional elasticity clearance space is needed from the prosthesis cavity; the condition is not met, and the affected area is ignored. If the fluctuation value equals 3.8 mm, it indicates the bone protrusion is just at the injury threshold; for safety reasons, this condition is also not met, and the affected area is ignored. If the fluctuation value is greater than 3.8 mm, it indicates significant bone protrusion during movement, easily causing pressure pain; the condition is met. The affected area is selected as the prosthesis cavity elasticity clearance area. Pre-defined dimensional measurement rules are assigned to this area. To determine the preset relaxation coefficient in the reserved size measurement rules, pressure was applied to the corresponding protruding sites on 200 subjects using a miniature pressure gauge, and the peak pressure at which moderate pain was induced was recorded as 250 kPa. Using material mechanics formulas, the required expansion ratio to achieve a pressure below 250 kPa in the prosthesis cavity was determined to be 0.45. This 0.45 was set as the preset relaxation coefficient. The upper limit value for the residual limb's anteroposterior diameter was extracted. The calculations in the reserved size measurement rules were performed. The clearance extension distance was calculated by multiplying the anteroposterior diameter fluctuation value by the preset relaxation coefficient 0.45. The upper limit value for the residual limb's anteroposterior diameter measurement was added to the calculated clearance extension distance to obtain the final anteroposterior diameter span. This final anteroposterior diameter span was assigned to the prosthesis socket elastic clearance size data.

[0034] S503: The basic contour of the combined prosthesis socket, the reserved gap of the prosthesis socket, the fitting dimensions of the basic prosthesis socket, and the elastic clearance dimensions of the prosthesis socket are used as the 3D dimension measurement results of the prosthesis socket. Extract the reserved gap of the prosthetic socket representing the volume difference of the sealed space. Extract the basic fitting dimension data of the prosthetic socket containing the absolute perimeter physical dimensions. Extract the elastic clearance dimension data of the prosthetic socket containing the final anterior-posterior diameter span. Set the three-dimensional spatial coordinate system of the basic contour of the prosthetic socket as a globally unique reference architecture system. Import all outward coordinate points corresponding to the reserved gap of the prosthetic socket into the reference architecture system, and use the outward coordinate points to replace the original vertex coordinates of the deformable dimension area of ​​the residual limb in the reference architecture system, so that the basic contour of the prosthetic socket exhibits an outward convex geometric deformation on the surface of the deformable dimension area of ​​the residual limb. Read the original perimeter value of a specific horizontal section within the basic fitting area of ​​the prosthetic socket. Calculate the perimeter scaling ratio by dividing the basic fitting dimension data of the prosthetic socket by the original perimeter value. Multiply the horizontal and vertical coordinate values ​​of all vertex coordinates within the basic fitting area of ​​the prosthetic socket by the perimeter scaling ratio to complete the repositioning of the three-dimensional node coordinates. At this point, the perimeter of the closed contour of the section is exactly equal to the design calculation value. The coordinates of the foremost point of the elastic relief zone of the prosthesis socket within the baseline framework are determined. The upper limit value of the original residual limb's anteroposterior diameter measurement is extracted. The offset distance is obtained by subtracting this upper limit value from the elastic relief zone dimensions. This offset distance is then added to the longitudinal coordinates of the foremost point and surrounding related vertices to complete the outward expansion and repositioning of the 3D node coordinates of the elastic relief zone. After completing the data combination and coordinate node modification for all different regions, the point cloud data within the baseline framework is updated to a completely new 3D surface mesh without any data conflicts. This new 3D surface mesh is exported as a standard 3D printing format file, and finally, the exported standard 3D printing format file is used to generate the 3D dimension measurement results of the prosthesis socket.

[0035] Please see Figure 7 A 3D size measurement system for prostheses, comprising: The consistency calculation module collects structured light point clouds of the same limb under each preset state, constructs a multi-state coordinate matching set of the limb, and calculates the coordinate displacement consistency parameters of the limb under the multi-state coordinate matching set of the limb. The gap extraction module determines the basic contour of the prosthesis socket based on the consistency parameters of the residual limb coordinate displacement, and extracts the reserved gap of the prosthesis socket from the basic contour data of the prosthesis socket. The range determination module, based on the multi-state coordinate matching set of the residual limb, determines the fluctuation range of the residual limb's perimeter and the fluctuation range of the residual limb's anteroposterior diameter. The size data generation module marks the basic fitting area of ​​the prosthesis socket with reference to the fluctuation range of the residual limb circumference size, and generates the corresponding basic fitting size data of the prosthesis socket. The measurement result determination module marks the elastic clearance area of ​​the prosthesis socket with reference to the fluctuation range of the anterior and posterior diameter of the residual limb, and generates the elastic clearance dimension data of the prosthesis socket. This data is then combined with the basic contour of the prosthesis socket, the reserved gap of the prosthesis socket, and the basic fitting dimension data of the prosthesis socket to generate the 3D dimension measurement result of the prosthesis socket.

[0036] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for 3D measurement of the dimensions of a prosthesis, characterized in that, Includes the following steps: S1: Collect structured light point clouds of the same residual limb under each preset state, construct a multi-state coordinate matching set of the residual limb, and calculate the coordinate displacement consistency parameter of the residual limb under the multi-state coordinate matching set; wherein, the preset state is specifically the natural relaxation state, the load-bearing state, and the standard positioning state. S2: Based on the residual limb coordinate displacement consistency parameters, determine the basic contour of the prosthesis socket and extract the reserved gap of the prosthesis socket from the basic contour data of the prosthesis socket; the reserved gap of the prosthesis socket includes the easily deformable size area of ​​the residual limb and the alignment coordinate points; Step S2 is as follows: S201: Compare the residual limb coordinate displacement consistency parameter with the preset soft tissue displacement judgment threshold one by one, and determine the corresponding residual limb anatomical area where the residual limb coordinate displacement consistency parameter of all the aligned coordinate points is lower than the soft tissue displacement judgment threshold, and divide it into the residual limb stable size area. S202: Extract the alignment coordinate points corresponding to the stable size region of the residual limb from the multi-state coordinate matching set of the residual limb, and establish the basic contour of the prosthesis socket. S203: The residual limb anatomical area corresponding to the residual limb coordinate displacement consistency parameter being higher than the soft tissue displacement judgment threshold is divided into the residual limb easily deformable size area. The alignment coordinate points corresponding to the residual limb easily deformable size area are extracted from the residual limb multi-state coordinate matching set to generate the reserved gap of the prosthesis socket. S3: Based on the multi-state coordinate matching set of the residual limb, determine the fluctuation range of the perimeter of the residual limb and the fluctuation range of the anterior-posterior diameter of the residual limb; S4: Mark the basic fitting area of ​​the prosthesis socket according to the fluctuation range of the residual limb circumference, and generate the corresponding basic fitting size data of the prosthesis socket; Step S4 is as follows: S401: Obtain the basic fit upper limit threshold corresponding to the prosthesis socket, and extract the circumference fluctuation value of the residual limb annular region within the residual limb anatomical area by referring to the fluctuation range of the residual limb circumference. S402: Select the residual limb ring area where the circumference fluctuation value is lower than the basic fit upper limit threshold, and mark it as the basic fit area of ​​the prosthesis socket; S403: Assign fixed size measurement rules to the basic fitting area of ​​the prosthesis socket and calculate the basic fitting size data of the prosthesis socket; wherein, the fixed size measurement rules are: basic fitting size data of the prosthesis socket = lower limit value of residual limb circumference measurement × 0.65 + upper limit value of residual limb circumference measurement × 0.35; S5: Mark the elastic clearance area of ​​the prosthesis socket according to the fluctuation range of the anterior and posterior diameter of the residual limb, and generate the elastic clearance size data of the prosthesis socket. Combine the data with the basic contour of the prosthesis socket, the reserved gap of the prosthesis socket, and the basic fitting size data of the prosthesis socket to generate the 3D size measurement result of the prosthesis socket. Step S5 is as follows: S501: Obtain the lower limit threshold of elastic clearance corresponding to the prosthesis socket, and extract the anteroposterior diameter fluctuation value corresponding to the local area of ​​the residual limb within the anatomical area of ​​the residual limb, referring to the fluctuation range of the anteroposterior diameter of the residual limb. S502: Select the local area of ​​the residual limb corresponding to the anteroposterior diameter fluctuation value being higher than the lower limit threshold of elasticity allowance, mark it as the elasticity allowance area of ​​the prosthesis socket, assign a reserved size measurement rule to the elasticity allowance area of ​​the prosthesis socket, and calculate the elasticity allowance size data of the prosthesis socket; wherein, the reserved size measurement rule is: elasticity allowance size data of the prosthesis socket = upper limit value of the anteroposterior diameter measurement of the residual limb + anteroposterior diameter fluctuation value × 0.45; S503: Combine the basic contour of the prosthesis socket, the data on the fit between the reserved gap of the prosthesis socket and the basic dimensions of the prosthesis socket, and the data on the elastic clearance dimensions of the prosthesis socket to obtain the 3D dimension measurement result of the prosthesis socket.

2. The method for measuring the dimensions of a prosthesis in 3D according to claim 1, characterized in that, The stump coordinate displacement consistency parameter is specifically calculated by the coordinate displacement deviation value. The stump circumference fluctuation range is specifically calculated by the deviation value between the upper limit value and the lower limit value of the stump circumference measurement. The stump anteroposterior diameter fluctuation range is specifically calculated by the deviation value between the upper limit value and the lower limit value of the stump anteroposterior diameter measurement. The prosthesis socket basic fit size data includes the stump annular region, the prosthesis socket basic fit area, and fixed size measurement rules. The prosthesis socket elastic clearance size data includes the stump local region, the prosthesis socket elastic clearance area, and reserved size measurement rules.

3. The method for measuring the dimensions of a prosthesis in 3D according to claim 1, characterized in that, Step S1 is as follows: S101: Collect the structured light point cloud of the same limb under various preset states, including the natural relaxation state, the load-bearing state, and the standard positioning state. Integrate the structured light point cloud of the limb under each state into multiple sets of three-dimensional surface point sets of the limb. Calculate the displacement change between the corresponding three-dimensional surface point sets of the limb under each state to obtain the non-rigid displacement field of the limb. S102: Extract the coordinate offset of each three-dimensional coordinate point from the non-rigid displacement field of the residual limb, calculate the coordinate offset and the coordinate sum between the corresponding three-dimensional coordinate points in the three-dimensional surface point set of the residual limb, and generate aligned coordinate points; S103: Integrate each of the aligned coordinate points belonging to the same anatomical region of the residual limb, establish a multi-state coordinate matching set of the residual limb, calculate the coordinate displacement deviation value of each of the aligned coordinate points within the anatomical region of the residual limb in the multi-state coordinate matching set of the residual limb, and obtain the coordinate displacement consistency parameter of the residual limb.

4. The method for measuring the dimensions of a prosthesis in 3D according to claim 1, characterized in that, Step S3 is as follows: S301: Based on the multi-state coordinate matching set of the residual limb, for the same residual limb anatomical region in the stable size region and the easily deformable size region of the residual limb, calculate the residual limb perimeter measurement value and residual limb anterior-posterior diameter measurement value in the same residual limb anatomical region under multiple states in the same residual limb anatomical region; S302: Based on the measured values ​​of the residual limb circumference and the measured values ​​of the residual limb anteroposterior diameter, determine the upper limit value and the lower limit value of the residual limb circumference measurement under multiple states, as well as the upper limit value and the lower limit value of the residual limb anteroposterior diameter measurement under multiple states. S303: Calculate the deviation between the upper limit and lower limit of the residual limb circumference measurement to generate the residual limb circumference fluctuation range; calculate the deviation between the upper limit and lower limit of the residual limb anteroposterior diameter measurement to generate the residual limb anteroposterior diameter fluctuation range.

5. The method for measuring the dimensions of a prosthesis in 3D according to claim 1, characterized in that, The fixed-size measurement rules are determined based on the upper limit value and the lower limit value of the residual limb circumference measurement corresponding to the basic fitting area of ​​the prosthesis socket.

6. The method for measuring the dimensions of a prosthesis in 3D according to claim 1, characterized in that, The fixed-size measurement rules are determined based on the upper limit value of the residual limb anteroposterior diameter measurement corresponding to the elastic relief area of ​​the prosthesis socket and the anteroposterior diameter fluctuation value.

7. A 3D size measurement system for a prosthesis, characterized in that, The system is used to implement the 3D size measurement method for a prosthesis according to any one of claims 1-6, the system comprising: The consistency calculation module collects structured light point clouds of the same limb under each preset state, constructs a multi-state coordinate matching set of the limb, and calculates the coordinate displacement consistency parameters of the limb under the multi-state coordinate matching set of the limb. The gap extraction module determines the basic contour of the prosthesis socket based on the residual limb coordinate displacement consistency parameters and extracts the reserved gap of the prosthesis socket from the basic contour data of the prosthesis socket. The range determination module determines the fluctuation range of the perimeter of the residual limb and the fluctuation range of the anteroposterior diameter of the residual limb based on the multi-state coordinate matching set of the residual limb. The size data generation module marks the basic fitting area of ​​the prosthesis socket with reference to the fluctuation range of the residual limb circumference size, and generates the corresponding basic fitting size data of the prosthesis socket. The measurement result determination module marks the elastic clearance area of ​​the prosthesis socket with reference to the fluctuation range of the anterior and posterior diameter of the residual limb, and generates elastic clearance size data of the prosthesis socket. This data is then combined with the basic contour of the prosthesis socket, the reserved gap of the prosthesis socket, and the basic fitting size data of the prosthesis socket to generate 3D size measurement results of the prosthesis socket.

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