High-precision tubular bone specimen liquid-guided laser cutting method

Abstract

A high-precision tubular bone specimen liquid guide laser cutting method; in turn meet the requirements: preoperative CT image reconstruction three-dimensional anatomical model and identify cortical bone and cancellous bone distribution area; the laser head posture data and bone profile data are fused; error solving; according to the anatomical classification of tubular bone, the target tubular bone is divided into long tubular bone and short tubular bone, and the differentiated initial cutting parameter configuration is established respectively: adjust the laser power, cutting speed; finally, the NURBS curve is generated to generate the target cutting section. The application first proposes a differentiated cutting strategy based on the classification of tubular bone, so as to establish a differentiated initial cutting parameter configuration. The application also proposes an effective slip prevention and parameter self-adaptive adjustment to ensure the cutting quality according to the anatomical characteristics of the smooth surface of the tubular bone, the non-uniform structure and the heat sensitivity. The application realizes the sub-millimeter level accurate control of the cutting depth, and ensures the cutting effect of the bone specimen.

Description

Technical Field

[0001] This invention relates to the field of laser cutting application technology for ex vivo bone, bone specimens, or bone models, and particularly to a liquid-guided laser cutting method for high-precision tubular bone specimens (which include natural biological bone specimens + artificial bone models / prostheses; ex vivo bone specimens, animal bone samples, artificial bone prostheses, and 3D printed bone models all belong to bone specimens, etc.). Background Technology

[0002] Cutting high-precision tubular bone specimens from ex vivo bones, bone samples, or bone models presents intractable technical challenges. Taking the long bones of the limbs (femur, tibia, humerus, radius, ulna, etc.) and the short tubular bones of the hands and feet (metacarpals, phalanges, metatarsals, phalanges, etc.) as examples, they are all tubular bone structures and represent the anatomical sites with the highest fracture rate in trauma orthopedics. Long tubular bones (humerus, ulna, radius, femur, tibia, and fibula) bear the main weight-bearing and movement functions. They have thick shafts, thick cortical bone, and prominent medullary cavities. Fractures of these bones are mostly caused by high-energy trauma. In medical technology training involving cutting ex vivo bones or bone models, the fixation requirements for bone specimens are extremely high (especially alignment accuracy and anti-rotation stability). Short tubular bones (metacarpals, phalanges, metatarsals, and phalanges), on the other hand, are small in size, have extremely thin bone walls, and are surrounded by dense tendons and neurovascular bundles within the body. Fractures of these bones are mostly caused by low-energy direct trauma, requiring much higher cutting precision and protection of surrounding tissues than long tubular bones. Statistics show that tubular bone fractures account for more than 60% of all fractures.

[0003] In internal fixation surgery for tubular bone fractures, precise bone cutting and segment trimming are crucial for surgical success. Therefore, medical simulation training for bone specimens such as extracted bone, bone samples, or bone models faces many core technical bottlenecks; these are briefly described below: First, the smooth surface of tubular bones causes instruments to slip. Long tubular bones are cylindrical, with the bone shaft covered by the periosteum, and are smooth and hard; short tubular bones are small in size and have a greater surface curvature. Traditional oscillating saws and bone drills are prone to lateral slippage when contacting the bone surface, especially on oblique fractures or irregular bone surfaces near joints. Slippage not only causes the cutting position to deviate from the preoperative plan, but may also damage surrounding important blood vessels, nerves and tendons, causing serious iatrogenic injury.

[0004] Secondly, the anatomical differences between long and short tubular bones lead to drastically different cutting requirements, which current technologies cannot differentiate between. Long tubular bones have large shafts (femoral shaft diameter can reach 25-30mm) and thick cortical bone (mid-shaft femoral cortical bone thickness reaches 6-8mm), requiring lasers with sufficient penetration depth and cutting efficiency. Short tubular bones (such as phalanges with a diameter of only 10-15mm and cortical bone thickness less than 2mm) require extremely high energy control precision; even slight over-energy can lead to full-thickness penetration or thermal damage spreading to surrounding tissues. However, current laser cutting methods use the same cutting parameter system for tubular bones of different sizes, lacking a classification strategy for the differentiated anatomical characteristics of long and short tubular bones, severely impacting cutting results.

[0005] Third, the mechanical cutting precision is insufficient. Traditional oscillating saws have a relatively large kerf width (0.8-1.2mm), and the oscillation of the saw blade during cutting can cause slight positional shifts. For short tubular bone surgery, the kerf width is close to 1 / 10 of the bone's diameter, making the precision issue particularly prominent. Studies have shown that an angular deviation of more than 5° on the bone cutting surface can significantly affect the fit of plates and the holding force of screws commonly used in simulation training practices such as orthopedic ex vivo bone or bone models.

[0006] Fourth, mechanical vibration and thermal damage. The oscillating saw and bone drill generate significant mechanical vibration, which can easily cause microcracks in bone tissue and damage to bone cells. The vibration transmitted to the fracture ends can also interfere with the alignment of a reduced fracture. Simultaneously, mechanical friction generates a large amount of heat, causing the local temperature of the bone tissue to rise above 47°C, which can potentially lead to bone cell necrosis. For short tubular bones, due to the smaller bone mass and smaller heat dissipation area, the risk of thermal damage is even higher.

[0007] Existing water-guided laser cutting methods are mostly designed for industrial materials (such as semiconductors, metals, and composite materials), while specialized methods for cutting tubular bone tissue, especially those for differentiating between long and short tubular bones, are lacking. Although industrial irregular tube cutting methods also involve laser processing of tubular materials, they process metallic or non-metallic tubes with uniform material properties, definite wall thickness, and regular geometry. They do not involve the anisotropy of biological tissues, the differences in bone wall thickness, and the sensitivity to thermal damage, which are complex issues. The two methods differ fundamentally in their technical approaches and core challenges.

[0008] There is an urgent need for training programs that simulate the cutting of bone specimens such as tubular exoskeletons or bone models, in order to help practitioners effectively improve their medical skills and proficiency. Summary of the Invention

[0009] This invention provides a high-precision liquid-guided laser cutting method for tubular bone specimens such as isolated bone and bone models.

[0010] The technical solution of this invention is as follows: A high-precision liquid-guided laser cutting method for tubular bone specimens; which sequentially meets the following requirements: Preoperative CT images were used to reconstruct a three-dimensional anatomical model and identify the distribution areas of cortical and cancellous bone; Multi-source data fusion is performed between laser head posture data and skeletal contour data; The error is solved by calling the thermal deformation compensation model; Based on the anatomical classification of tubular bones, the target tubular bones are for the first time divided into long tubular bones (humerus, ulna, radius, femur, tibia, fibula) and short tubular bones (metacarpals, phalanges, metatarsals, phalanges). Differential initial cutting parameter configurations are established for each type of tubular bone, taking into account their essential differences in bone wall thickness, medullary cavity size, etc. For long tubular bones, higher power (30-50W) and a larger liquid jet diameter (0.8-1.5mm) are used to achieve rapid penetration of thick-walled cortical bone; for short tubular bones, lower power (5-15W) and a smaller liquid jet diameter (0.3-0.6mm) are used to avoid full-thickness penetration and thermal damage diffusion. The laser power is adjusted according to the bone wall thickness, and the cutting speed is adjusted according to the radius of curvature of the tubular bone surface. The radius of curvature compensation coefficient for short tubular bones is adjusted to a gradient of 1.5-2 times that for long tubular bones. Finally, NURBS curves are constructed to generate the target cutting segments.

[0011] This invention proposes for the first time a differentiated cutting strategy based on the type of tubular bone, which effectively solves the problem of different cutting requirements for long and short tubular bones due to differences in anatomical structure, and fills the technical gap in existing laser cutting methods that cannot distinguish between tubular bones of different sizes.

[0012] The high-precision tubular bone specimen liquid-guided laser cutting method of the present invention; its implementation steps and contents sequentially meet the following requirements: Step 1: Acquire CT image data of the target tubular bone, reconstruct a three-dimensional anatomical model of the tubular bone, identify and label the distribution areas and boundaries of cortical and cancellous bone; and determine the category of the target tubular bone based on the three-dimensional anatomical model: when the target tubular bone is the humerus, ulna, radius, femur, tibia, or fibula, it is classified as a long tubular bone; when the target tubular bone is a metacarpal, phalanx, metatarsal, or phalanx, it is classified as a short tubular bone. In the three-dimensional anatomical model of the tubular bone, the distribution areas of cortical bone and cancellous bone are automatically identified and labeled using the CT value threshold segmentation method. Step 2: Based on the type of the target tubular bone, adopt a differentiated initial cutting parameter configuration strategy: If the target tubular bone is a long tubular bone, the first initial parameter configuration is as follows: laser wavelength is selected as 2.94μm Er:YAG laser, initial power is set to 30-50W, initial cutting speed is set to 8-15mm / s, liquid jet pressure is set to 1.5-2.5MPa, and liquid jet diameter is set to 0.8-1.5mm. If the target tubular bone is a short tubular bone, the second initial parameter configuration is adopted: the laser wavelength is selected as 2.1μm Ho:YAG laser or 1904nm thulium laser, the initial power is set to 5-15W, the initial cutting speed is set to 3-8mm / s, the liquid jet pressure is set to 0.5-1.2MPa, and the liquid jet diameter is set to 0.3-0.6mm; In the differentiated initial parameter configuration for the long tubular bone and the short tubular bone, the long tubular bone uses higher power and a larger liquid jet diameter to achieve rapid penetration of thick-walled cortical bone, while the short tubular bone uses lower power and a smaller liquid jet diameter to avoid full-thickness penetration and thermal damage diffusion. Step 3: Obtain laser head posture data and bone contour data of discrete sampling points of tubular bone that correspond one-to-one with the discrete sampling points of laser head on the preset cutting path; First, obtain the bone wall thickness and radius of curvature parameters of the target tubular bone in the current surgical batch, and set the basic cutting speed and basic laser power of the liquid-guided laser cutting device associated with the target tubular bone; The laser head posture data, the corresponding bone contour data, the bone wall thickness, the radius of curvature parameter, the basic cutting speed, and the basic laser power are fused from multiple sources to obtain the target contour data of the reference cutting points that correspond one by one with the discrete sampling points of the laser head. Step 4: Take each pair of adjacent reference cutting points on the cutting path as the starting point and ending point of the same cutting segment, respectively, and call the preset thermal deformation compensation model to solve the error of the starting point and ending point of the same cutting segment to obtain the compensation attitude data of multiple compensation control points of the same cutting segment. Step 5: Based on the thickness range of the bone wall, the base laser power is increased using the power compensation coefficient corresponding to the thickness range to obtain the target laser power; based on the radius range of the curvature radius of the tubular bone surface, the base cutting speed is adjusted using the speed compensation coefficient corresponding to the radius range to obtain the first target cutting speed; wherein, the curvature radius compensation coefficient adjustment gradient for short tubular bones is 1.5-2 times that for long tubular bones; Step 6: Construct a NURBS curve based on the compensation attitude data of the multiple compensation control points of the same cutting segment, the first target cutting speed, and the target laser power to generate a target cutting segment; determine the laser cutting trajectory and the tubular bone feed trajectory based on the target cutting segment.

[0013] The high-precision tubular bone specimen liquid-guided laser cutting method of the present invention; a further preferred embodiment of the claimed technical content is: In step 4, the following requirements must also be met: The thermal deformation compensation model indicates that the temperature gradients at the starting point, middle point, and ending point of the same cutting segment are all the same. The process involves calling a preset thermal deformation compensation model to solve for errors at the start and end points of the same cutting segment, obtaining compensation attitude data for multiple compensation control points of the same cutting segment, including: Based on the temperature gradient model of the thermal deformation compensation model, the first correlation between the first compensation control point and the starting point of the cutting segment and the second correlation between the second compensation control point and the ending point of the cutting segment are determined respectively. Based on the temperature gradient model, a third correlation relationship is determined between the midpoint of the cutting segment and the starting point, the ending point, the first compensation control point, and the second compensation control point; The temperature change rate is determined based on the first correlation, the second correlation, and the third correlation. Based on the first correlation, the temperature change rate, the compensation attitude data of the starting point of the cutting segment, and the control point tangent vector, the compensation attitude data of the first compensation control point is obtained. Based on the second correlation, the temperature change rate, the compensation attitude data of the end point of the cutting segment, and the control point tangent vector, the compensation attitude data of the second compensation control point is obtained; Among them, the first compensation control point, the second compensation control point, the starting point of the cutting segment, and the ending point of the cutting segment are all compensation control points.

[0014] In step 4, the following requirement is also met: when the starting point of the cutting segment is the first reference cutting point on the cutting path; the control point tangent vector of the starting point of the cutting segment is obtained by performing the following steps through the starting point tangent vector calculation model: The control point tangent vector of the next reference cutting point of the starting point of the cutting segment is obtained through the starting point tangent vector calculation model and used as the first control point tangent vector, and the first curve smoothing index of the next reference cutting point of the starting point of the cutting segment is obtained. The control point tangent vector is obtained by performing a weighted difference operation on the first control point tangent vector and the first curve smoothing index through the starting point tangent vector calculation model; the curve smoothing index characterizes the curvature change relationship between the reference cutting point and the previous reference cutting point.

[0015] When the endpoint of the cutting segment is the last reference cutting point on the cutting path, the control point tangent vector of the endpoint of the cutting segment is determined by performing the following steps through the endpoint tangent vector calculation model: The control point tangent vector of the previous reference cutting point of the cutting segment endpoint is obtained through the endpoint tangent vector calculation model and used as the second control point tangent vector. The control point tangent vector is obtained by performing a weighted difference calculation on the curve smoothing index of the second control point tangent vector and the end point of the cutting segment using the endpoint tangent vector calculation model.

[0016] The control point tangent vectors at the starting point and the ending point of the cutting segment are both determined by performing the following steps through the intermediate node tangent vector calculation model: The curve smoothing index of the current benchmark cutting point and the curve smoothing index of the next benchmark cutting point are obtained through the intermediate node tangent vector calculation model and used as the second curve smoothing index and the third curve smoothing index, respectively. The node scalar change coefficient of the current reference cutting point is obtained through the intermediate node tangent vector calculation model. The node scalar change coefficient represents the relationship between the node scalar difference of the current reference cutting point and the node scalar difference of the next reference cutting point. The control point tangent vector of the current reference cutting point is determined by weighted summation of the node scalar change coefficient, the second curve smoothing index, and the third curve smoothing index through the intermediate node tangent vector calculation model. The starting point of the cutting segment is any reference cutting point other than the first reference cutting point, and the ending point of the cutting segment is any reference cutting point other than the last reference cutting point.

[0017] The curve smoothing index is the ratio of the coordinate vector difference between two adjacent reference cut points to the node scalar difference; the node scalar change coefficient is the ratio of the node scalar difference of the current reference cut point to the total node vector difference, and the ratio of the total node vector difference is the sum of the node scalar difference of the current reference cut point and the node scalar difference of the next reference cut point.

[0018] Based on the compensation attitude data of the multiple compensation control points of the same cutting segment, the first target cutting speed, and the target laser power, a NURBS curve is constructed to generate the target cutting segment, including: The compensated attitude data of the reference cutting points of different cutting segments are respectively input into the preset node scalar constraint model to obtain the node vector corresponding to the cutting segment where the starting point of the cutting segment is located; NURBS curves are constructed based on the node vectors and the corresponding compensation attitude data of the multiple compensation control points.

[0019] The high-precision tubular bone specimen liquid-guided laser cutting method also meets the following requirements: Based on the radius range of the curvature radius of the tubular bone surface, the base cutting speed is adjusted using a speed compensation coefficient corresponding to the radius range to obtain a first target cutting speed, including: When the radius of curvature of the tubular bone surface is greater than a first preset radius, the base cutting speed is adjusted based on the radius range in which the radius of curvature of the tubular bone surface is located, using a speed compensation coefficient corresponding to the radius range, to obtain a first target cutting speed. The speed compensation coefficient includes a deceleration ratio and a maintenance ratio. The radius range includes multiple ranges, and each radius range corresponds to a deceleration ratio. The smaller the value of the radius range, the larger the deceleration ratio corresponding to the radius range. When the radius of curvature of the tubular bone surface is less than or equal to the first preset radius and greater than the second preset radius, the basic cutting speed is taken as the first target cutting speed.

[0020] When the radius of curvature of the tubular bone surface is less than or equal to the second preset radius, the base laser power is increased based on the thickness range of the bone wall thickness using the power compensation coefficient corresponding to the thickness range to obtain the target laser power. The thickness range includes multiple ranges, each corresponding to a power increase ratio, and the larger the value of the thickness range, the larger the power increase ratio corresponding to the thickness range. During subsequent cutting strokes, if the real-time cutting speed of the target tubular bone is less than the first target cutting speed, the motion mechanism of the liquid-guided laser cutting device is controlled to accelerate to the first target cutting speed.

[0021] The specific method for controlling the motion mechanism of the liquid-guided laser cutting device to accelerate to the first target cutting speed is as follows: When the current cutting position of the target tubular bone is a section with a sudden change in the curvature of the tubular bone (such as the junction of the diaphysis and metaphysis of a long tubular bone, or the junction of the epiphysis and diaphysis of a short tubular bone), and the real-time cutting speed is less than the first target cutting speed, the liquid-guided laser cutting device is controlled to operate in a first acceleration mode. The first acceleration mode is the speed adjustment mode of the liquid-guided laser cutting device in a high dynamic response state. Determine a second target cutting speed associated with the first target cutting speed, wherein the second target cutting speed is less than the first target cutting speed; During the subsequent cutting stroke, if the real-time cutting speed of the target tubular bone is less than the second target cutting speed, the liquid-guided laser cutting device is controlled to operate in a second deceleration mode. The second deceleration mode is a speed adjustment mode of the liquid-guided laser cutting device when it is close to the edge or inflection point of the tubular bone. The state of being close to the edge or inflection point of the tubular bone includes the state of the cutting head being close to the curvature change point of the tubular bone surface.

[0022] The beneficial effects of this invention are as follows: In summary, the advantages of this invention are: (1) The first proposed differential cutting strategy based on the category of tubular bones: The present invention is the first to classify the target tubular bones into long tubular bones (humerus, ulna, radius, femur, tibia, fibula) and short tubular bones (metacarpals, phalanges, metatarsals, phalanges) based on the anatomical classification of tubular bones. Differentiated initial cutting parameters are established for the two types of tubular bones based on their essential differences in bone wall thickness, medullary cavity size, and distribution of surrounding tissues.

[0023] For long tubular bones, higher power (30-50W) and a larger liquid jet diameter (0.8-1.5mm) are used to achieve rapid penetration of thick-walled cortical bone; for short tubular bones, lower power (5-15W) and a smaller liquid jet diameter (0.3-0.6mm) are used to avoid full-thickness penetration and the spread of thermal damage to surrounding tendons and nerves. This classification strategy fills the technical gap in existing laser cutting methods that cannot distinguish between tubular bones of different sizes, significantly broadens the applicability of the method for operational simulation training on ex vivo bone and bone models, and has important reference value for orthopedic surgery on patients.

[0024] (2) Effectively avoiding slippage due to the smooth anatomical characteristics of tubular bone surfaces: This invention obtains data on the radius of curvature distribution of the tubular bone surface and adaptively adjusts the cutting speed using a corresponding speed compensation coefficient. It automatically decelerates in areas with smaller radii of curvature (such as the metaphysis of long tubular bones and the epiphysis of short tubular bones), ensuring that the laser cutting head moves closely to the bone surface, effectively avoiding the lateral slippage problem caused by the smoothness of the tubular bone surface, a problem common with traditional mechanical tools. Specifically, the radius of curvature compensation coefficient adjustment gradient for short tubular bones is 1.5-2 times that for long tubular bones to accommodate their smaller geometric dimensions and more abrupt changes in surface curvature, significantly improving the positional and angular accuracy of tubular bone cutting.

[0025] (3) Different from industrial irregular tube cutting methods: Existing industrial irregular tube laser cutting methods deal with metal or non-metal tubes, which have uniform material properties, definite wall thickness and regular geometric shape, and do not involve the anisotropy of biological tissues, the difference in bone wall thickness and the sensitivity to thermal damage. This invention is specifically designed for the non-uniform structure of biological tubular bones (alternating distribution of cortical bone and cancellous bone, significant differences in bone wall thickness in different parts) and thermal sensitivity (irreversible necrosis of bone cells can occur above 47°C). By identifying the distribution area of ​​cortical bone and cancellous bone through CT images before cutting, and identifying tissue type and adaptively adjusting parameters in real time during cutting, high-precision low-damage cutting of tubular bones, a special "workpiece", is achieved. It is fundamentally different from industrial tube cutting in terms of technical path and core difficulties.

[0026] (4) Adaptive adjustment of parameters for different anatomical locations of tubular bones: This invention achieves adaptive adjustment of cutting parameters for different anatomical locations of tubular bones (thick-walled area of ​​the diaphysis, thin-walled area of ​​the metaphysis, and cancellous bone area of ​​the articular end of long tubular bones; diaphysis and epiphysis of short tubular bones) by adjusting the cutting speed and laser power according to the bone wall thickness and surface curvature radius of the tubular bone. Higher power is used in areas with thicker bone walls to ensure complete cutting, while power is appropriately reduced in areas with thinner bone walls to avoid penetration damage, and automatic deceleration is used in areas with smaller curvature radius to ensure cutting quality.

[0027] (5) Achieving sub-millimeter-level precise control of cutting depth: This invention improves the cutting depth control accuracy to better than ±0.1mm through real-time depth monitoring and adaptive closed-loop control using OCT, which is significantly better than the accuracy level of traditional mechanical tools and single-wavelength laser systems. For short tubular bone surgery, this level of accuracy means that precise control can be achieved within a bone wall thickness of less than 2mm, ensuring the cutting effect on bone specimens such as isolated bone or bone models; and it has important reference value for avoiding damage to surrounding tendons and neurovascular bundles in real orthopedic surgery. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the overall method steps in Embodiment 2 of the present invention. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Example 1 A high-precision liquid-guided laser cutting method for tubular bone specimens; its main contents meet the following requirements in sequence: Preoperative CT images were used to reconstruct a three-dimensional anatomical model and identify the distribution areas of cortical and cancellous bone; Multi-source data fusion is performed between laser head posture data and skeletal contour data; The error is solved by calling the thermal deformation compensation model; Based on the anatomical classification of tubular bones, the target tubular bones are for the first time divided into long tubular bones (humerus, ulna, radius, femur, tibia, fibula) and short tubular bones (metacarpals, phalanges, metatarsals, phalanges). Differential initial cutting parameter configurations are established for each type of tubular bone, taking into account their essential differences in bone wall thickness, medullary cavity size, etc. For long tubular bones, higher power (30-50W) and a larger liquid jet diameter (0.8-1.5mm) are used to achieve rapid penetration of thick-walled cortical bone; for short tubular bones, lower power (5-15W) and a smaller liquid jet diameter (0.3-0.6mm) are used to avoid full-thickness penetration and thermal damage diffusion. The laser power is adjusted according to the bone wall thickness, and the cutting speed is adjusted according to the radius of curvature of the tubular bone surface. The radius of curvature compensation coefficient for short tubular bones is adjusted to a gradient of 1.5-2 times that for long tubular bones. Finally, NURBS curves are constructed to generate the target cutting segments.

[0031] This embodiment proposes for the first time a differentiated cutting strategy based on the type of tubular bone, which effectively solves the problem of different cutting requirements for long and short tubular bones due to differences in anatomical structure, and fills the technical gap in existing laser cutting methods that cannot distinguish between tubular bones of different sizes.

[0032] The high-precision tubular bone specimen liquid-guided laser cutting method described in this embodiment; its implementation steps and contents sequentially meet the following requirements: Step 1: Acquire CT image data of the target tubular bone, reconstruct a three-dimensional anatomical model of the tubular bone, identify and label the distribution areas and boundaries of cortical and cancellous bone; and determine the category of the target tubular bone based on the three-dimensional anatomical model: when the target tubular bone is the humerus, ulna, radius, femur, tibia, or fibula, it is classified as a long tubular bone; when the target tubular bone is a metacarpal, phalanx, metatarsal, or phalanx, it is classified as a short tubular bone. In the three-dimensional anatomical model of the tubular bone, the distribution areas of cortical bone and cancellous bone are automatically identified and labeled using the CT value threshold segmentation method. Step 2: Based on the type of the target tubular bone, adopt a differentiated initial cutting parameter configuration strategy: If the target tubular bone is a long tubular bone, the first initial parameter configuration is as follows: laser wavelength is selected as 2.94μm Er:YAG laser, initial power is set to 30-50W, initial cutting speed is set to 8-15mm / s, liquid jet pressure is set to 1.5-2.5MPa, and liquid jet diameter is set to 0.8-1.5mm. If the target tubular bone is a short tubular bone, the second initial parameter configuration is adopted: the laser wavelength is selected as 2.1μm Ho:YAG laser or 1904nm thulium laser, the initial power is set to 5-15W, the initial cutting speed is set to 3-8mm / s, the liquid jet pressure is set to 0.5-1.2MPa, and the liquid jet diameter is set to 0.3-0.6mm; In the differentiated initial parameter configuration for the long tubular bone and the short tubular bone, the long tubular bone uses higher power and a larger liquid jet diameter to achieve rapid penetration of thick-walled cortical bone, while the short tubular bone uses lower power and a smaller liquid jet diameter to avoid full-thickness penetration and thermal damage diffusion. Step 3: Obtain laser head posture data and bone contour data of discrete sampling points of tubular bone that correspond one-to-one with the discrete sampling points of laser head on the preset cutting path; First, obtain the bone wall thickness and radius of curvature parameters of the target tubular bone in the current surgical batch, and set the basic cutting speed and basic laser power of the liquid-guided laser cutting device associated with the target tubular bone; The laser head posture data, the corresponding bone contour data, the bone wall thickness, the radius of curvature parameter, the basic cutting speed, and the basic laser power are fused from multiple sources to obtain the target contour data of the reference cutting points that correspond one by one with the discrete sampling points of the laser head. Step 4: Take each pair of adjacent reference cutting points on the cutting path as the starting point and ending point of the same cutting segment, respectively, and call the preset thermal deformation compensation model to solve the error of the starting point and ending point of the same cutting segment to obtain the compensation attitude data of multiple compensation control points of the same cutting segment. The thermal deformation compensation model indicates that the temperature gradients at the starting point, middle point, and ending point of the same cutting segment are all the same. The process involves calling a preset thermal deformation compensation model to solve for errors at the start and end points of the same cutting segment, obtaining compensation attitude data for multiple compensation control points of the same cutting segment, including: Based on the temperature gradient model of the thermal deformation compensation model, the first correlation between the first compensation control point and the starting point of the cutting segment and the second correlation between the second compensation control point and the ending point of the cutting segment are determined respectively. Based on the temperature gradient model, a third correlation relationship is determined between the midpoint of the cutting segment and the starting point, the ending point, the first compensation control point, and the second compensation control point; The temperature change rate is determined based on the first correlation, the second correlation, and the third correlation. Based on the first correlation, the temperature change rate, the compensation attitude data of the starting point of the cutting segment, and the control point tangent vector, the compensation attitude data of the first compensation control point is obtained. Based on the second correlation, the temperature change rate, the compensation attitude data of the end point of the cutting segment, and the control point tangent vector, the compensation attitude data of the second compensation control point is obtained; Among them, the first compensation control point, the second compensation control point, the starting point of the cutting segment, and the ending point of the cutting segment are all compensation control points.

[0033] When the starting point of the cutting segment is the first reference cutting point on the cutting path, the control point tangent vector of the starting point of the cutting segment is obtained by performing the following steps through the starting point tangent vector calculation model: The control point tangent vector of the next reference cutting point of the starting point of the cutting segment is obtained through the starting point tangent vector calculation model and used as the first control point tangent vector, and the first curve smoothing index of the next reference cutting point of the starting point of the cutting segment is obtained. The control point tangent vector is obtained by performing a weighted difference operation on the first control point tangent vector and the first curve smoothing index through the starting point tangent vector calculation model; the curve smoothing index characterizes the curvature change relationship between the reference cutting point and the previous reference cutting point.

[0034] When the endpoint of the cutting segment is the last reference cutting point on the cutting path, the control point tangent vector of the endpoint of the cutting segment is determined by performing the following steps through the endpoint tangent vector calculation model: The control point tangent vector of the previous reference cutting point of the cutting segment endpoint is obtained through the endpoint tangent vector calculation model and used as the second control point tangent vector. The control point tangent vector is obtained by performing a weighted difference calculation on the curve smoothing index of the second control point tangent vector and the end point of the cutting segment using the endpoint tangent vector calculation model.

[0035] The control point tangent vectors at the starting point and the ending point of the cutting segment are both determined by performing the following steps through the intermediate node tangent vector calculation model: The curve smoothing index of the current benchmark cutting point and the curve smoothing index of the next benchmark cutting point are obtained through the intermediate node tangent vector calculation model and used as the second curve smoothing index and the third curve smoothing index, respectively. The node scalar change coefficient of the current reference cutting point is obtained through the intermediate node tangent vector calculation model. The node scalar change coefficient represents the relationship between the node scalar difference of the current reference cutting point and the node scalar difference of the next reference cutting point. The control point tangent vector of the current reference cutting point is determined by weighted summation of the node scalar change coefficient, the second curve smoothing index, and the third curve smoothing index through the intermediate node tangent vector calculation model. The starting point of the cutting segment is any reference cutting point other than the first reference cutting point, and the ending point of the cutting segment is any reference cutting point other than the last reference cutting point.

[0036] The curve smoothing index is the ratio of the coordinate vector difference between two adjacent reference cut points to the node scalar difference; the node scalar change coefficient is the ratio of the node scalar difference of the current reference cut point to the total node vector difference, and the ratio of the total node vector difference is the sum of the node scalar difference of the current reference cut point and the node scalar difference of the next reference cut point.

[0037] Based on the compensation attitude data of the multiple compensation control points of the same cutting segment, the first target cutting speed, and the target laser power, a NURBS curve is constructed to generate the target cutting segment, including: The compensated attitude data of the reference cutting points of different cutting segments are respectively input into the preset node scalar constraint model to obtain the node vector corresponding to the cutting segment where the starting point of the cutting segment is located; NURBS curves are constructed based on the node vectors and the corresponding compensation attitude data of the multiple compensation control points.

[0038] It also meets the following requirements: Based on the radius range of the curvature radius of the tubular bone surface, the base cutting speed is adjusted using a speed compensation coefficient corresponding to the radius range to obtain a first target cutting speed, including: When the radius of curvature of the tubular bone surface is greater than a first preset radius, the base cutting speed is adjusted based on the radius range in which the radius of curvature of the tubular bone surface is located, using a speed compensation coefficient corresponding to the radius range, to obtain a first target cutting speed. The speed compensation coefficient includes a deceleration ratio and a maintenance ratio. The radius range includes multiple ranges, and each radius range corresponds to a deceleration ratio. The smaller the value of the radius range, the larger the deceleration ratio corresponding to the radius range. When the radius of curvature of the tubular bone surface is less than or equal to the first preset radius and greater than the second preset radius, the basic cutting speed is taken as the first target cutting speed.

[0039] When the radius of curvature of the tubular bone surface is less than or equal to the second preset radius, the base laser power is increased based on the thickness range of the bone wall thickness using the power compensation coefficient corresponding to the thickness range to obtain the target laser power. The thickness range includes multiple ranges, each corresponding to a power increase ratio, and the larger the value of the thickness range, the larger the power increase ratio corresponding to the thickness range. During subsequent cutting strokes, if the real-time cutting speed of the target tubular bone is less than the first target cutting speed, the motion mechanism of the liquid-guided laser cutting device is controlled to accelerate to the first target cutting speed.

[0040] The specific method for controlling the motion mechanism of the liquid-guided laser cutting device to accelerate to the first target cutting speed is as follows: When the current cutting position of the target tubular bone is a section with a sudden change in the curvature of the tubular bone (such as the junction of the diaphysis and metaphysis of a long tubular bone, or the junction of the epiphysis and diaphysis of a short tubular bone), and the real-time cutting speed is less than the first target cutting speed, the liquid-guided laser cutting device is controlled to operate in a first acceleration mode. The first acceleration mode is the speed adjustment mode of the liquid-guided laser cutting device in a high dynamic response state. Determine a second target cutting speed associated with the first target cutting speed, wherein the second target cutting speed is less than the first target cutting speed; During the subsequent cutting stroke, if the real-time cutting speed of the target tubular bone is less than the second target cutting speed, the liquid-guided laser cutting device is controlled to operate in a second deceleration mode. The second deceleration mode is a speed adjustment mode of the liquid-guided laser cutting device when it is close to the edge or inflection point of the tubular bone. The state of being close to the edge or inflection point of the tubular bone includes the state of the cutting head being close to the curvature change point of the tubular bone surface.

[0041] Step 5: Based on the thickness range of the bone wall, the base laser power is increased using the power compensation coefficient corresponding to the thickness range to obtain the target laser power; based on the radius range of the curvature radius of the tubular bone surface, the base cutting speed is adjusted using the speed compensation coefficient corresponding to the radius range to obtain the first target cutting speed; wherein, the curvature radius compensation coefficient adjustment gradient for short tubular bones is 1.5-2 times that for long tubular bones; Step 6: Construct a NURBS curve based on the compensation attitude data of the multiple compensation control points of the same cutting segment, the first target cutting speed, and the target laser power to generate a target cutting segment; determine the laser cutting trajectory and the tubular bone feed trajectory based on the target cutting segment.

[0042] The beneficial effects of this embodiment are: In summary, the advantages of this embodiment are: (2) A differentiated cutting strategy based on the type of tubular bone is proposed for the first time: This embodiment classifies the target tubular bones into long tubular bones (humerus, ulna, radius, femur, tibia, fibula) and short tubular bones (metacarpals, phalanges, metatarsals, phalanges) based on the anatomical classification of tubular bones. Differentiated initial cutting parameters are established for the two types of tubular bones based on their essential differences in bone wall thickness, medullary cavity size, and distribution of surrounding tissues.

[0043] For long tubular bones, higher power (30-50W) and a larger liquid jet diameter (0.8-1.5mm) are used to achieve rapid penetration of thick-walled cortical bone; for short tubular bones, lower power (5-15W) and a smaller liquid jet diameter (0.3-0.6mm) are used to avoid full-thickness penetration and the spread of thermal damage to surrounding tendons and nerves. This classification strategy fills the technical gap in existing laser cutting methods that cannot distinguish between tubular bones of different sizes, significantly broadens the applicability of the method for operational simulation training on ex vivo bone and bone models, and has important reference value for orthopedic surgery on patients.

[0044] (2) Effectively avoiding slippage due to the smooth anatomical characteristics of tubular bone surfaces: This embodiment acquires data on the radius of curvature distribution of the tubular bone surface and adaptively adjusts the cutting speed using a corresponding speed compensation coefficient. Automatic deceleration occurs in areas with smaller radii of curvature (such as the metaphysis of long tubular bones and the epiphysis of short tubular bones), ensuring that the laser cutting head moves closely against the bone surface, effectively avoiding the lateral slippage problem caused by the smooth surface of tubular bones that occurs with traditional mechanical tools. Specifically, the radius of curvature compensation coefficient adjustment gradient for short tubular bones is 1.5-2 times that for long tubular bones to accommodate their smaller geometric dimensions and more abrupt changes in surface curvature, significantly improving the positional and angular accuracy of tubular bone cutting.

[0045] (3) Different from industrial irregular tube cutting methods: Existing industrial irregular tube laser cutting methods deal with metal or non-metal tubes, which have uniform material properties, definite wall thickness and regular geometric shape, and do not involve the anisotropy of biological tissues, the difference in bone wall thickness and the sensitivity to thermal damage. This embodiment is specifically designed for the non-uniform structure of biological tubular bone (alternating distribution of cortical bone and cancellous bone, significant differences in bone wall thickness in different parts) and thermal sensitivity (irreversible necrosis of bone cells can occur above 47°C). By identifying the distribution area of ​​cortical bone and cancellous bone through CT images before cutting, and identifying tissue type and adaptively adjusting parameters in real time during cutting, high-precision low-damage cutting of tubular bone, a special "workpiece", is achieved. It is fundamentally different from industrial tube cutting in terms of technical path and core difficulties.

[0046] (4) Adaptive adjustment of parameters for different anatomical locations of tubular bones: In this embodiment, the cutting speed and laser power are adjusted according to the bone wall thickness and surface curvature radius of the tubular bone to achieve adaptive adjustment of cutting parameters for different anatomical locations of the tubular bone (thick-walled area of ​​the diaphysis, thin-walled area of ​​the metaphysis, and cancellous bone area of ​​the articular end of long tubular bones; diaphysis and epiphysis of short tubular bones). Higher power is used in areas with thicker bone walls to ensure complete cutting, while power is appropriately reduced in areas with thinner bone walls to avoid penetrating damage, and automatic deceleration is used in areas with smaller curvature radius to ensure cutting quality.

[0047] (5) Achieving sub-millimeter-level precise control of cutting depth: This embodiment improves the cutting depth control accuracy to better than ±0.1mm through real-time depth monitoring and adaptive closed-loop control using OCT, which is significantly better than the accuracy level of traditional mechanical tools and single-wavelength laser systems. For short tubular bone surgery, this level of accuracy means that precise control can be achieved within a bone wall thickness of less than 2mm, ensuring the cutting effect for bone specimens such as isolated bone or bone models; and it has important reference value for avoiding damage to surrounding tendons and neurovascular bundles in real orthopedic surgery.

[0048] Example 2 In an alternative embodiment, please refer to Figure 1 This embodiment provides a technical solution: a high-precision tubular bone fluid-guided laser cutting method, comprising: S1. Obtain preoperative CT image data of the target tubular bone, reconstruct a three-dimensional anatomical model of the tubular bone, and identify and label the distribution area and boundary of cortical bone and cancellous bone. S2. Based on the three-dimensional anatomical model, determine the category of the target tubular bone: when the target tubular bone is the humerus, ulna, radius, femur, tibia, or fibula, classify it as a long tubular bone; when the target tubular bone is a metacarpal, phalanx, metatarsal, or phalanx, classify it as a short tubular bone. S3. Based on the type of the target tubular bone, adopt a differentiated initial cutting parameter configuration strategy: If the target tubular bone is a long tubular bone, the first initial parameter configuration is as follows: laser wavelength is selected as 2.94μm Er:YAG laser, initial power is set to 30-50W, initial cutting speed is set to 8-15mm / s, liquid jet pressure is set to 1.5-2.5MPa, and liquid jet diameter is set to 0.8-1.5mm. If the target tubular bone is a short tubular bone, the second initial parameter configuration is adopted: the laser wavelength is selected as 2.1μm Ho:YAG laser or 1904nm thulium laser, the initial power is set to 5-15W, the initial cutting speed is set to 3-8mm / s, the liquid jet pressure is set to 0.5-1.2MPa, and the liquid jet diameter is set to 0.3-0.6mm; S4. Obtain the laser head posture data corresponding to the discrete sampling points of the laser head on the preset cutting path and the bone contour data of the discrete sampling points of the tubular bone. S5. Obtain the bone wall thickness and radius of curvature parameters of the target tubular bone in the current surgical batch, and obtain the basic cutting speed and basic laser power of the liquid-guided laser cutting device associated with the target tubular bone; S6. The laser head posture data, the corresponding bone contour data, the bone wall thickness, the radius of curvature parameter, the basic cutting speed and the basic laser power are fused from multiple sources to obtain the target contour data of the reference cutting point that corresponds one-to-one with the discrete sampling point of the laser head. S7. Take each pair of adjacent reference cutting points on the cutting path as the starting point and ending point of the same cutting segment, respectively, and call the preset thermal deformation compensation model to solve the error of the starting point and ending point of the same cutting segment to obtain the compensation attitude data of multiple compensation control points of the same cutting segment. S8. Based on the thickness range of the bone wall, the base laser power is increased using the power compensation coefficient corresponding to the thickness range to obtain the target laser power; based on the radius range of the curvature radius of the tubular bone surface, the base cutting speed is adjusted using the speed compensation coefficient corresponding to the radius range to obtain the first target cutting speed; wherein, the curvature radius compensation coefficient adjustment gradient for short tubular bones is 1.5-2 times that for long tubular bones; S9. Construct a NURBS curve based on the compensation attitude data of the multiple compensation control points of the same cutting segment, the first target cutting speed and the target laser power, and generate a target cutting segment; determine the laser cutting trajectory and the tubular bone feed trajectory based on the target cutting segment.

[0049] It should be noted that this embodiment first obtains three-dimensional anatomical data of the target tubular bone through preoperative CT images, reconstructs a three-dimensional model, and identifies the distribution areas of cortical and cancellous bone. Subsequently, the target tubular bone is classified according to anatomical classification standards—the humerus, ulna, radius, femur, tibia, and fibula are classified as long tubular bones, while the metacarpals, phalanges, metatarsals, and phalanges are classified as short tubular bones. This classification has important clinical significance: long tubular bones have large shafts (femoral shaft diameter can reach 25-30mm), thick cortical bone (cortical bone thickness in the mid-shaft of the femur reaches 6-8mm), and bear the main weight-bearing function, requiring the laser to have sufficient penetration depth and cutting efficiency; while short tubular bones are small in size (phalanges diameter is only 10-15mm), have extremely thin bone walls (cortical bone thickness is less than 2mm), and are surrounded by dense tendons and neurovascular bundles, requiring much higher cutting precision and protection of surrounding tissues than long tubular bones.

[0050] Based on this classification, this embodiment employs differentiated initial cutting parameter configurations. For long tubular bones, a 2.94μm Er:YAG laser is selected. This wavelength has an extremely high absorption coefficient for water, enabling efficient ablation of superficial bone tissue. Combined with higher power (30-50W) and a larger jet diameter (0.8-1.5mm), rapid penetration of thick-walled cortical bone can be achieved while ensuring cutting quality. For short tubular bones, a 2.1μm Ho:YAG laser or a 1904nm thulium laser is selected, combined with lower power (5-15W) and a smaller jet diameter (0.3-0.6mm). This achieves precise cutting while minimizing full-thickness penetration and the spread of thermal damage to surrounding tendons and nerves.

[0051] In terms of cutting path planning, this embodiment fuses laser head posture data and bone contour data from multiple sources to calculate the target contour data of the reference cutting point corresponding to each laser head sampling point. Every two adjacent reference cutting points on the cutting path are defined as the start and end points of the same cutting segment. A thermal deformation compensation model is then used to calculate errors, obtaining the compensated posture data for the compensation control points. This process compensates for deviations caused by thermal deformation and other error factors during laser cutting, ensuring that the cutting path matches the actual shape of the tubular bone throughout the entire surgical procedure.

[0052] Regarding speed and power control, this embodiment adaptively adjusts the speed based on the bone wall thickness and surface curvature radius of the tubular bone. Specifically, the curvature radius compensation coefficient for short tubular bones is adjusted to a gradient of 1.5-2 times that for long tubular bones to accommodate their smaller geometry and more abrupt changes in surface curvature. Finally, a smooth target cutting segment is generated using NURBS curves, determining the laser cutting trajectory and the tubular bone feed trajectory. This ensures that the movement path of the cutting head precisely matches the actual shape of the tubular bone and the cutting parameters, minimizing cutting errors and avoiding the slippage problem that occurs with traditional mechanical tools due to the smooth surface of the tubular bone.

[0053] In an optional embodiment, the thermal deformation compensation model characterizes the temperature gradients at the starting point, midpoint, and ending point of the same cut segment as being identical. The step of calling a preset thermal deformation compensation model to solve for errors at the starting and ending points of the same cut segment, obtaining compensation attitude data for multiple compensation control points of the same cut segment, includes: Based on the temperature gradient model of the thermal deformation compensation model, the first correlation between the first compensation control point and the starting point of the cutting segment and the second correlation between the second compensation control point and the ending point of the cutting segment are determined respectively. Based on the temperature gradient model, a third correlation relationship is determined between the midpoint of the cutting segment and the starting point, the ending point, the first compensation control point, and the second compensation control point; The temperature change rate is determined based on the first correlation, the second correlation, and the third correlation. Based on the first correlation, the temperature change rate, the compensation attitude data of the starting point of the cutting segment, and the control point tangent vector, the compensation attitude data of the first compensation control point is obtained. Based on the second correlation, the temperature change rate, the compensation attitude data of the end point of the cutting segment, and the control point tangent vector, the compensation attitude data of the second compensation control point is obtained; Among them, the first compensation control point, the second compensation control point, the starting point of the cutting segment, and the ending point of the cutting segment are all compensation control points.

[0054] It should be noted that, according to the preset thermal deformation compensation model, it is assumed that the temperature gradients at the starting point, intermediate point, and ending point within the same cut segment are the same. For long tubular bones, due to the thicker bone wall and larger heat capacity, the time constant of thermal deformation is longer, and the temperature change rate is relatively gentle. For short tubular bones, due to the smaller bone mass and smaller heat capacity, thermal deformation is more sensitive, and the temperature change rate is more drastic. The thermal deformation compensation model in this embodiment achieves differentiated thermal deformation compensation by calculating the temperature change rate of the two types of tubular bones separately.

[0055] In an optional embodiment, when the starting point of the cutting segment is the first reference cutting point on the cutting path, the control point tangent vector of the starting point of the cutting segment is obtained by performing the following steps through the starting point tangent vector calculation model: The control point tangent vector of the next reference cutting point of the starting point of the cutting segment is obtained through the starting point tangent vector calculation model and used as the first control point tangent vector, and the first curve smoothing index of the next reference cutting point of the starting point of the cutting segment is obtained. The control point tangent vector is obtained by performing a weighted difference operation on the first control point tangent vector and the first curve smoothing index using the starting point tangent vector calculation model; the curve smoothing index characterizes the curvature change relationship between the reference cutting point and the previous reference cutting point.

[0056] In an optional embodiment, when the endpoint of the cutting segment is the last reference cutting point on the cutting path, the control point tangent vector of the endpoint of the cutting segment is determined by performing the following steps through the endpoint tangent vector calculation model: The control point tangent vector of the previous reference cutting point of the cutting segment endpoint is obtained through the endpoint tangent vector calculation model and used as the second control point tangent vector. The control point tangent vector is obtained by performing a weighted difference calculation on the curve smoothing index of the second control point tangent vector and the end point of the cutting segment using the endpoint tangent vector calculation model.

[0057] In an optional embodiment, the control point tangent vector at the starting point of the cutting segment and the control point tangent vector at the ending point of the cutting segment are both determined by performing the following steps through the intermediate node tangent vector calculation model: The curve smoothing index of the current benchmark cutting point and the curve smoothing index of the next benchmark cutting point are obtained through the intermediate node tangent vector calculation model and used as the second curve smoothing index and the third curve smoothing index, respectively. The node scalar change coefficient of the current reference cutting point is obtained through the intermediate node tangent vector calculation model. The node scalar change coefficient represents the relationship between the node scalar difference of the current reference cutting point and the node scalar difference of the next reference cutting point. The control point tangent vector of the current reference cutting point is determined by weighted summation of the node scalar change coefficient, the second curve smoothing index, and the third curve smoothing index through the intermediate node tangent vector calculation model. The starting point of the cutting segment is any reference cutting point other than the first reference cutting point, and the ending point of the cutting segment is any reference cutting point other than the last reference cutting point.

[0058] In an optional embodiment, a target cutting segment is generated by constructing a NURBS curve based on the compensation attitude data of the plurality of compensation control points of the same cutting segment, the first target cutting speed, and the target laser power, including: The compensated attitude data of the reference cutting points of different cutting segments are respectively input into the preset node scalar constraint model to obtain the node vector corresponding to the cutting segment where the starting point of the cutting segment is located; NURBS curves are constructed based on the node vectors and the corresponding compensation attitude data of the multiple compensation control points.

[0059] In an optional embodiment, the basic cutting speed is adjusted according to the radius range of the curvature radius of the tubular bone surface, using a speed compensation coefficient corresponding to the radius range, to obtain a first target cutting speed, including: When the radius of curvature of the tubular bone surface is greater than a first preset radius, the base cutting speed is adjusted based on the radius range in which the radius of curvature of the tubular bone surface is located, using a speed compensation coefficient corresponding to the radius range, to obtain a first target cutting speed. The speed compensation coefficient includes a deceleration ratio and a maintenance ratio. The radius range includes multiple ranges, and each radius range corresponds to a deceleration ratio. The smaller the value of the radius range, the larger the deceleration ratio corresponding to the radius range. When the radius of curvature of the tubular bone surface is less than or equal to the first preset radius and greater than the second preset radius, the basic cutting speed is taken as the first target cutting speed.

[0060] For short tubular bones, due to their small size and more abrupt changes in surface curvature, this embodiment features a more sensitive speed compensation mechanism. The curvature radius compensation coefficient adjustment gradient for short tubular bones is 1.5-2 times that for long tubular bones. This means that for the same change in curvature radius, the speed adjustment range for short tubular bones is greater, ensuring that the cutting head can closely adhere to the bone surface when moving over small bone surfaces such as phalanges and metacarpals, avoiding cutting deviations or slippage caused by excessive speed.

[0061] In an optional embodiment, the method further includes: When the radius of curvature of the tubular bone surface is less than or equal to the second preset radius, the base laser power is increased based on the thickness range in which the bone wall thickness is located, using the power compensation coefficient corresponding to the thickness range to obtain the target laser power; the thickness range includes multiple ranges, each thickness range corresponds to a power increase ratio, and the larger the value of the thickness range, the larger the power increase ratio corresponding to the thickness range. During subsequent cutting strokes, if the real-time cutting speed of the target tubular bone is less than the first target cutting speed, the motion mechanism of the liquid-guided laser cutting device is controlled to accelerate to the first target cutting speed.

[0062] In an optional embodiment, controlling the motion mechanism of the liquid-guided laser cutting device to accelerate to the first target cutting speed includes: When the current cutting position of the target tubular bone is a section with a sudden change in the curvature of the tubular bone (such as the junction of the diaphysis and metaphysis of a long tubular bone, the junction of the metaphysis and articular surface, or the junction of the epiphysis and diaphysis of a short tubular bone), and the real-time cutting speed is less than the first target cutting speed, the liquid-guided laser cutting device is controlled to operate in a first acceleration mode. The first acceleration mode is the speed adjustment mode of the liquid-guided laser cutting device in a high dynamic response state. Determine a second target cutting speed associated with the first target cutting speed, wherein the second target cutting speed is less than the first target cutting speed; During the subsequent cutting stroke, if the real-time cutting speed of the target tubular bone is less than the second target cutting speed, the liquid-guided laser cutting device is controlled to operate in a second deceleration mode. The second deceleration mode is a speed adjustment mode of the liquid-guided laser cutting device when it is close to the edge or inflection point of the tubular bone. The state of being close to the edge or inflection point of the tubular bone includes the state of the cutting head being close to the curvature change point of the tubular bone surface.

[0063] For short tubular bones, due to their small size and more frequent and severe curvature changes, this embodiment adopts higher response sensitivity in the speed control of the curvature change section to ensure a smooth cutting transition in complex geometric areas such as phalangeal joint surfaces and metacarpal heads.

Claims

1. A high-precision liquid-guided laser cutting method for tubular bone specimens; characterized in that: They sequentially satisfy the following requirements: Preoperative CT images were used to reconstruct a three-dimensional anatomical model and identify the distribution areas of cortical and cancellous bone; Multi-source data fusion is performed between laser head posture data and skeletal contour data; The error is solved by calling the thermal deformation compensation model; Based on the anatomical classification of tubular bones, the target tubular bones are divided into long tubular bones and short tubular bones. Differential initial cutting parameter configurations are established for each type of tubular bone, taking into account their essential differences in bone wall thickness, medullary cavity size, etc. For long tubular bones, a higher power (30-50W) and a larger liquid jet diameter (0.8-1.5mm) are used to achieve rapid penetration of thick-walled cortical bone; for short tubular bones, a lower power (5-15W) and a smaller liquid jet diameter (0.3-0.6mm) are used to avoid full-thickness penetration and thermal damage diffusion. The laser power is adjusted according to the bone wall thickness, and the cutting speed is adjusted according to the radius of curvature of the tubular bone surface. The radius of curvature compensation coefficient for short tubular bones is adjusted to a gradient of 1.5-2 times that for long tubular bones. Finally, NURBS curves are constructed to generate the target cutting segments.

2. The high-precision tubular bone specimen liquid-guided laser cutting method according to claim 1; characterized in that: Its steps and contents must meet the following requirements in sequence: Step 1: Acquire CT image data of the target tubular bone, reconstruct a three-dimensional anatomical model of the tubular bone, identify and label the distribution areas and boundaries of cortical and cancellous bone; and determine the category of the target tubular bone based on the three-dimensional anatomical model: when the target tubular bone is the humerus, ulna, radius, femur, tibia or fibula, it is classified as a long tubular bone; when the target tubular bone is a metacarpal, phalanx, metatarsal or phalanx, it is classified as a short tubular bone. In the three-dimensional anatomical model of the tubular bone, the distribution areas of cortical bone and cancellous bone are automatically identified and labeled using the CT value threshold segmentation method. Step 2: Based on the type of the target tubular bone, adopt a differentiated initial cutting parameter configuration strategy: If the target tubular bone is a long tubular bone, the first initial parameter configuration is as follows: laser wavelength is selected as 2.94μm Er:YAG laser, initial power is set to 30-50W, initial cutting speed is set to 8-15mm / s, liquid jet pressure is set to 1.5-2.5MPa, and liquid jet diameter is set to 0.8-1.5mm. If the target tubular bone is a short tubular bone, the second initial parameter configuration is adopted: the laser wavelength is selected as 2.1μm Ho:YAG laser or 1904nm thulium laser, the initial power is set to 5-15W, the initial cutting speed is set to 3-8mm / s, the liquid jet pressure is set to 0.5-1.2MPa, and the liquid jet diameter is set to 0.3-0.6mm; Step 3: Obtain laser head posture data and bone contour data of discrete sampling points of tubular bone that correspond one-to-one with the discrete sampling points of laser head on the preset cutting path; First, obtain the bone wall thickness and radius of curvature parameters of the target tubular bone in the current surgical batch, and set the basic cutting speed and basic laser power of the liquid-guided laser cutting device associated with the target tubular bone; The laser head posture data, the corresponding bone contour data, the bone wall thickness, the radius of curvature parameter, the basic cutting speed, and the basic laser power are fused from multiple sources to obtain the target contour data of the reference cutting points that correspond one by one with the discrete sampling points of the laser head. Step 4: Take each pair of adjacent reference cutting points on the cutting path as the starting point and ending point of the same cutting segment, respectively, and call the preset thermal deformation compensation model to solve the error of the starting point and ending point of the same cutting segment to obtain the compensation attitude data of multiple compensation control points of the same cutting segment. Step 5: Based on the thickness range of the bone wall, the base laser power is increased using the power compensation coefficient corresponding to the thickness range to obtain the target laser power; based on the radius range of the curvature radius of the tubular bone surface, the base cutting speed is adjusted using the speed compensation coefficient corresponding to the radius range to obtain the first target cutting speed; wherein, the curvature radius compensation coefficient adjustment gradient for short tubular bones is 1.5-2 times that for long tubular bones; Step 6: Construct a NURBS curve based on the compensation attitude data of the multiple compensation control points of the same cutting segment, the first target cutting speed, and the target laser power to generate a target cutting segment; determine the laser cutting trajectory and the tubular bone feed trajectory based on the target cutting segment.

3. The high-precision tubular bone specimen liquid-guided laser cutting method according to claim 2; characterized in that: In step 4, the following requirements must also be met: The thermal deformation compensation model indicates that the temperature gradients at the starting point, middle point, and ending point of the same cutting segment are all the same. The process involves calling a preset thermal deformation compensation model to solve for errors at the start and end points of the same cutting segment, obtaining compensation attitude data for multiple compensation control points of the same cutting segment, including: Based on the temperature gradient model of the thermal deformation compensation model, the first correlation between the first compensation control point and the starting point of the cutting segment and the second correlation between the second compensation control point and the ending point of the cutting segment are determined respectively. Based on the temperature gradient model, a third correlation relationship is determined between the midpoint of the cutting segment and the starting point, the ending point, the first compensation control point, and the second compensation control point; The temperature change rate is determined based on the first correlation, the second correlation, and the third correlation. Based on the first correlation, the temperature change rate, the compensation attitude data of the starting point of the cutting segment, and the control point tangent vector, the compensation attitude data of the first compensation control point is obtained. Based on the second correlation, the temperature change rate, the compensation attitude data of the end point of the cutting segment, and the control point tangent vector, the compensation attitude data of the second compensation control point is obtained; Among them, the first compensation control point, the second compensation control point, the starting point of the cutting segment, and the ending point of the cutting segment are all compensation control points.

4. The high-precision tubular bone specimen liquid-guided laser cutting method according to claim 3; characterized in that: In step 4, the following requirement is also met: when the starting point of the cutting segment is the first reference cutting point on the cutting path; the control point tangent vector of the starting point of the cutting segment is obtained by performing the following steps through the starting point tangent vector calculation model: The control point tangent vector of the next reference cutting point of the starting point of the cutting segment is obtained through the starting point tangent vector calculation model and used as the first control point tangent vector, and the first curve smoothing index of the next reference cutting point of the starting point of the cutting segment is obtained. The control point tangent vector is obtained by performing a weighted difference operation on the first control point tangent vector and the first curve smoothing index through the starting point tangent vector calculation model; the curve smoothing index characterizes the curvature change relationship between the reference cutting point and the previous reference cutting point.

5. The high-precision tubular bone specimen liquid-guided laser cutting method according to claim 3 or 4; characterized in that: In step 4, the following requirements must also be met: When the endpoint of the cutting segment is the last reference cutting point on the cutting path, the control point tangent vector of the endpoint of the cutting segment is determined by performing the following steps through the endpoint tangent vector calculation model: The control point tangent vector of the previous reference cutting point of the cutting segment endpoint is obtained through the endpoint tangent vector calculation model and used as the second control point tangent vector. The control point tangent vector is obtained by performing a weighted difference calculation on the curve smoothing index of the second control point tangent vector and the end point of the cutting segment using the endpoint tangent vector calculation model.

6. The high-precision tubular bone specimen liquid-guided laser cutting method according to claim 5; characterized in that: In step 4, the following requirements must also be met: The control point tangent vectors at the starting point and the ending point of the cutting segment are both determined by performing the following steps through the intermediate node tangent vector calculation model: The curve smoothing index of the current benchmark cutting point and the curve smoothing index of the next benchmark cutting point are obtained through the intermediate node tangent vector calculation model and used as the second curve smoothing index and the third curve smoothing index, respectively. The node scalar change coefficient of the current reference cutting point is obtained through the intermediate node tangent vector calculation model. The node scalar change coefficient represents the relationship between the node scalar difference of the current reference cutting point and the node scalar difference of the next reference cutting point. The control point tangent vector of the current reference cutting point is determined by weighted summation of the node scalar change coefficient, the second curve smoothing index, and the third curve smoothing index through the intermediate node tangent vector calculation model. The starting point of the cutting segment is any reference cutting point other than the first reference cutting point, and the ending point of the cutting segment is any reference cutting point other than the last reference cutting point.

7. The high-precision tubular bone specimen liquid-guided laser cutting method according to claim 6; characterized in that: In step 4, the following requirements are also met: the curve smoothing index is the ratio of the coordinate vector difference between two adjacent reference cut points to the node scalar difference; the node scalar change coefficient is the ratio of the node scalar difference of the current reference cut point to the total node vector difference, and the ratio of the total node vector difference is the sum of the node scalar difference of the current reference cut point and the node scalar difference of the next reference cut point.

8. The high-precision tubular bone specimen liquid-guided laser cutting method according to claim 7; characterized in that: In step 4, the following requirements must also be met: Based on the compensation attitude data of the multiple compensation control points of the same cutting segment, the first target cutting speed, and the target laser power, a NURBS curve is constructed to generate the target cutting segment, including: The compensated attitude data of the reference cutting points of different cutting segments are respectively input into the preset node scalar constraint model to obtain the node vector corresponding to the cutting segment where the starting point of the cutting segment is located; NURBS curves are constructed based on the node vectors and the corresponding compensation attitude data of the multiple compensation control points.

9. The high-precision tubular bone specimen liquid-guided laser cutting method according to claim 8; characterized in that: The high-precision tubular bone specimen liquid-guided laser cutting method also meets the following requirements: Based on the radius range of the curvature radius of the tubular bone surface, the base cutting speed is adjusted using a speed compensation coefficient corresponding to the radius range to obtain a first target cutting speed, including: When the radius of curvature of the tubular bone surface is greater than a first preset radius, the base cutting speed is adjusted based on the radius range in which the radius of curvature of the tubular bone surface is located, using a speed compensation coefficient corresponding to the radius range, to obtain a first target cutting speed. The speed compensation coefficient includes a deceleration ratio and a maintenance ratio. The radius range includes multiple ranges, and each radius range corresponds to a deceleration ratio. The smaller the value of the radius range, the larger the deceleration ratio corresponding to the radius range. When the radius of curvature of the tubular bone surface is less than or equal to the first preset radius and greater than the second preset radius, the basic cutting speed is taken as the first target cutting speed.

10. The high-precision tubular bone specimen liquid-guided laser cutting method according to claim 9; characterized in that: In step 4, the following requirements must also be met: When the radius of curvature of the tubular bone surface is less than or equal to the second preset radius, the base laser power is increased based on the thickness range of the bone wall thickness using the power compensation coefficient corresponding to the thickness range to obtain the target laser power. The thickness range includes multiple ranges, each corresponding to a power increase ratio, and the larger the value of the thickness range, the larger the power increase ratio corresponding to the thickness range. During subsequent cutting strokes, if the real-time cutting speed of the target tubular bone is less than the first target cutting speed, the motion mechanism of the liquid-guided laser cutting device is controlled to accelerate to the first target cutting speed. The specific method for controlling the motion mechanism of the liquid-guided laser cutting device to accelerate to the first target cutting speed is as follows: When the current cutting position of the target tubular bone is a section with a sudden change in the curvature of the tubular bone, and the real-time cutting speed is less than the first target cutting speed, the liquid-guided laser cutting device is controlled to operate in a first acceleration mode. The first acceleration mode is the speed adjustment mode of the liquid-guided laser cutting device in a high dynamic response state. Determine a second target cutting speed associated with the first target cutting speed, wherein the second target cutting speed is less than the first target cutting speed; During the subsequent cutting stroke, if the real-time cutting speed of the target tubular bone is less than the second target cutting speed, the liquid-guided laser cutting device is controlled to operate in a second deceleration mode. The second deceleration mode is a speed adjustment mode of the liquid-guided laser cutting device when it is close to the edge or inflection point of the tubular bone. The state of being close to the edge or inflection point of the tubular bone includes the state of the cutting head being close to the curvature change point of the tubular bone surface.

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