Method, device, medium and equipment for constructing temperature model of bone grinding by mechanical arm ultrasonic drill

Abstract

This invention provides a method, apparatus, medium, and equipment for constructing a temperature model for ultrasonic bone grinding using a robotic arm. The method includes: obtaining a theoretical temperature analysis model for ultrasonic bone grinding based on the motion process of the ultrasonic drill; establishing a finite element analysis model for ultrasonic bone grinding based on the theoretical temperature analysis model to obtain the influence of bone density, the vibration amplitude of the cylindrical drill of the ultrasonic equipment, and the feed rate on the grinding temperature; and establishing a temperature model for ultrasonic bone grinding based on the finite element analysis model to obtain a mathematical characterization of the relationship between grinding temperature and bone density, vibration amplitude, and feed rate. According to the technical solution provided by this invention, the construction of a temperature model for ultrasonic bone grinding using a robotic arm can be realized.

Description

Technical Field

[0001] This invention relates to a method, apparatus, medium, and equipment for constructing a temperature model for ultrasonic grinding of bone by a robotic arm, belonging to the field of robotic bone grinding. Background Technology

[0002] Robotic ultrasonic grinding technology offers significant advantages in bone tissue processing, including low thermal damage and high precision. Establishing a temperature model is crucial for the safe and efficient application of this technology. This model clarifies the quantitative correlation between multiple factors, such as ultrasonic vibration parameters, bone tissue physical properties, and robotic arm motion parameters, and the grinding temperature during bone grinding. It provides accurate prediction and control data to prevent thermal necrosis of bone tissue and ensure the safety of surrounding biological tissues. Furthermore, it serves as a core input for developing robotic thermal management strategies, ensuring the biosafety of the surgery. Therefore, establishing an accurate and reliable temperature model for robotic ultrasonic grinding is essential for improving the safety of intelligent orthopedic surgery.

[0003] Currently, the construction of relevant temperature models is mainly based on multi-physics coupled numerical analysis. Such simulations require the integration of knowledge from multiple fields such as heat transfer, biomechanics, and ultrasonic dynamics, involving multiple physical processes such as ultrasonic energy dissipation, unsteady heat conduction in bone tissue, and convective heat transfer in cooling media. The constructed models typically suffer from limitations such as complex structures, numerous boundary conditions, and high computational resource consumption, making it difficult to meet the needs of rapid prediction and real-time control of temperature changes during surgery. Therefore, researching a method for constructing a temperature model for robotic arm ultrasonic bone grinding that combines depth of physical mechanism understanding with potential for real-time engineering applications has significant value in both academic frontier exploration and clinical application. Summary of the Invention

[0004] The purpose of this invention is to provide a method, apparatus, medium, and equipment for constructing a temperature model for ultrasonic drilling and bone grinding using a robotic arm, aiming to solve the problem of constructing a temperature model for ultrasonic drilling and bone grinding using a robotic arm, and at the same time, to provide a theoretical basis for the research of ultrasonic drilling and grinding systems for robotic arms.

[0005] This invention provides a method for constructing a mechanical model for robotic bone grinding, comprising:

[0006] S1. Based on the motion process of ultrasonic grinding, a theoretical temperature analysis model for ultrasonic bone grinding is obtained.

[0007] S2. Based on the temperature theory analysis model, a finite element analysis model for ultrasonic bone grinding is established to obtain the influence of bone density, the vibration amplitude of the cylindrical drill of the ultrasonic equipment, and the feed rate on the grinding temperature.

[0008] S3. Based on the finite element analysis model, a temperature model for ultrasonic bone grinding is established to obtain the mathematical characterization of the relationship between grinding temperature and bone density, vibration amplitude and feed rate.

[0009] In the above-described method, obtaining the temperature theoretical analysis model for ultrasonic bone grinding based on the motion process of ultrasonic grinding includes:

[0010] Based on the kinematic characteristics and frictional heat generation principle of ultrasonic grinding, the heat at the grinding interface mainly comes from high-frequency friction. The normal friction force is determined by the grinding force in the feed direction and the friction coefficient.

[0011] The average heat flux transmitted to the bone tissue is obtained based on the normal friction force, the equivalent cutting speed dominated by ultrasonic vibration, and the contact area between the tool and the bone.

[0012] Based on the Jaeger moving heat source model, the ultrasonic grinding process is regarded as a moving strip heat source, and the basic relationship between temperature rise and grinding force, amplitude, feed rate and bone density is obtained.

[0013] Furthermore, considering the dynamic changes in friction coefficient with amplitude, the change in heat distribution ratio with feed rate, and the nonlinear dependence of bone thermophysical parameters on bone density in actual grinding, undetermined coefficients are introduced.

[0014] Based on the above temperature theory analysis model, the relationship between ultrasonic grinding temperature and feed rate, ultrasonic amplitude, and bone density was analyzed, which will serve as the theoretical basis for the construction of the temperature model.

[0015] In the above-described method, based on the temperature theory analysis model, a finite element analysis model for ultrasonic bone grinding is established to obtain the influence of bone density, the vibration amplitude of the cylindrical drill of the ultrasonic equipment, and the feed rate on the grinding temperature, including:

[0016] Solid geometric models of the cylindrical drill and bone were constructed using 3D modeling software, and the generated solid geometric models were imported into finite element simulation software.

[0017] Based on the inherent material properties of the bone model and the cylindrical grinding head, the density elasticity, material model, damage model, specific heat, and thermal conductivity of the bone model and the cylindrical grinding head are constructed.

[0018] Based on the relative positional relationships in a real grinding scenario, multiple components are instantiated and combined into a complete model in the assembly. Among them, the cylindrical grinding head is simplified into a rigid body with a reference point.

[0019] Based on the geometric features, material properties, analysis step size, and thermodynamic characteristics of the finite element model, a precise layered mesh is created for the bone model and the cylindrical grinding head.

[0020] Based on the bone grinding process in a real grinding scenario, the bottom surface of the bone model is constrained and fixed to simulate the fixed support effect under real conditions; the interaction between the bone model and the cylindrical grinding head is constructed, and the contact type, contact properties, heat conduction and constraints between the bone model and the cylindrical grinding head are set.

[0021] Based on the actual bone grinding process, the load parameters of the finite element model are set to simulate the bone grinding motion process of the ultrasonic drill.

[0022] Based on the above conditions, the thermodynamic behavior of the bone model and the cylindrical grinding head was analyzed using the method of explicit dynamic temperature displacement analysis. By analyzing the average grinding temperature of the stable grinding process in multiple simulation results, it was found that the grinding temperature increases with the increase of bone density; the grinding temperature increases with the increase of ultrasonic amplitude of the cylindrical grinding head of the robotic arm; and the grinding temperature decreases with the increase of feed speed of the cylindrical grinding head of the robotic arm.

[0023] Based on the above finite element analysis model, data on the grinding temperature in the feed direction under different bone densities, ultrasonic amplitudes, and feed speeds were collected to provide data support for the temperature model.

[0024] In the above-described method, the establishment of a temperature model for ultrasonic bone grinding based on a finite element analysis model, and the mathematical characterization of the relationship between grinding temperature and bone density, vibration amplitude, and feed rate, includes:

[0025] Based on the above finite element analysis model, multiple sets of simulation experiments were designed, and the data were processed based on the simulation results to fit the model parameters.

[0026] Based on the above temperature model, conduct physical experiments, draw safety parameter boundaries, and evaluate the accuracy and applicability of the temperature model.

[0027] Based on the above temperature model, a mathematical representation of the relationship between grinding temperature, vibration amplitude, and feed rate is obtained, which will serve as the basis for optimizing and controlling the motion parameters of ultrasonic grinding drill bone grinding in robotic arms.

[0028] As can be seen from the above technical solutions, the present invention has the following beneficial effects:

[0029] The technical solution of this invention provides a temperature model for ultrasonic bone grinding with a robotic arm, which clarifies the quantitative correlation between multiple factors such as ultrasonic vibration parameters, bone tissue physical properties, and robotic arm motion parameters and the grinding temperature during bone grinding. This provides a crucial theoretical basis for effectively preventing bone tissue necrosis due to overheating. Attached Figure Description

[0030] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the 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 any creative effort or labor.

[0031] Figure 1 This is a flowchart of the method for constructing a temperature model for ultrasonic grinding of bone by a robotic arm, as provided in this invention example;

[0032] Figure 2 This is a schematic diagram of the ultrasonic processing motion model provided in the embodiments of the present invention;

[0033] Figure 3 This is a schematic diagram of the bone model and cylindrical grinding head provided in the example of the present invention;

[0034] Figure 4 The following is a schematic diagram of finite element analysis provided in the embodiments of the present invention: (a) a three-dimensional model of grinding; (b) the bone model and the cylindrical grinding head mesh; (c) the interaction between the bone model and the cylindrical grinding head; (d) the load constraints of the bone model and the cylindrical grinding head;

[0035] Figure 5 Here are schematic diagrams of the spatiotemporal distribution of the finite element simulation provided in this embodiment of the invention: (a) Cut-in state; (b) Steady state;

[0036] Figure 6 These are the results of finite element simulation experiments under different parameter combinations;

[0037] Figure 7 This is a schematic diagram showing the change of grinding temperature in the feed direction over time at different feed rates in the finite element simulation provided in this embodiment of the invention.

[0038] Figure 8 This is a schematic diagram of the change of grinding temperature over time in the feed direction under different ultrasonic amplitudes in the finite element simulation provided in the embodiments of the present invention;

[0039] Figure 9 This is a schematic diagram of the change of grinding temperature in the feed direction with time under different bone densities in the finite element simulation provided in the embodiments of the present invention;

[0040] Figure 10 This is a comparison chart of simulation and physical experiment results under different working conditions in the embodiments of the present invention;

[0041] Figure 11 These are temperature model thermograms under different operating conditions in embodiments of the present invention; Specific Implementation

[0042] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. 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.

[0043] This invention provides a method for constructing a temperature model for ultrasonic grinding of bone by a robotic arm. Please refer to [link / reference]. Figure 1 This is a flowchart illustrating the method for constructing a temperature model for ultrasonic bone grinding using a robotic arm, as provided by this invention. The temperature model for ultrasonic bone grinding using a robotic arm can accurately quantify the dynamic relationship between bone density, ultrasonic vibration parameters, robotic arm motion parameters, and grinding temperature, effectively avoiding excessive bone tissue damage caused by excessive grinding temperature. Specifically, it includes the following steps:

[0044] Step S1: Based on the motion process of ultrasonic grinding, obtain the theoretical temperature analysis model for ultrasonic bone grinding.

[0045] Specifically, such as Figure 2 As shown, the machining motion of the ultrasonic grinding drill tool in this embodiment is to apply periodic high-frequency simple harmonic vibrations in the cutting direction and the depth of cut direction while maintaining the feed motion in the grinding direction, and at the same time apply a low-speed rotational oscillation.

[0046] Based on the kinematic characteristics and frictional heat generation principle of ultrasonic grinding, the heat at the grinding interface mainly originates from high-frequency friction. The normal friction force is determined by the grinding force in the feed direction and the coefficient of friction. for:

[0047]

[0048] in, It is the coefficient of friction between the ultrasonic drill bit and bone tissue. It is the grinding force in the feed direction obtained by the surface response method.

[0049] The average heat flux transmitted to the bone tissue is obtained based on normal friction, the equivalent cutting speed dominated by ultrasonic vibration, and the contact area between the tool and the bone. .

[0050] In ultrasonic machining, the cutting head vibrates at high frequency, and the equivalent cutting speed is mainly determined by the ultrasonic vibration. It can be approximated by ultrasonic amplitude and ultrasonic frequency as follows:

[0051]

[0052] in, This refers to the amplitude of the ultrasonic drill. This refers to the frequency of the ultrasonic drill.

[0053] Total power generated in the cutting zone The main cause is the cutting action of the blade on the bone, which is represented as:

[0054]

[0055] Average heat flux into bones Represented as:

[0056]

[0057] in, The heat distribution coefficient, This represents the contact area between the knife and the bone. For the contact arc length, This refers to the contact width.

[0058] Based on the Jaeger moving heat source model, the ultrasonic grinding process is considered as a moving strip heat source, and the highest surface temperature caused by the moving heat source is... Depends on the Peckley number , Represented as:

[0059]

[0060] in, It is the thermal diffusivity of bone. It is thermal conductivity. It's bone density. It is specific heat capacity.

[0061] Because bone tissue has extremely low thermal conductivity, the calculated Pecklet number will be relatively large (usually greater than 5). Based on the large Pecklet number approximation solution of Jaeger's moving heat source theory, the following is derived:

[0062]

[0063] in, It is the reference temperature.

[0064] Will and Substitute into In the formula, the constant terms are combined, separating the variables and material constants:

[0065]

[0066] Furthermore, considering the dynamic changes in friction coefficient with amplitude, the change in heat distribution ratio with feed rate, and the nonlinear dependence of bone thermophysical parameters on bone density in actual grinding, undetermined coefficients are introduced.

[0067] Specifically, a bias coefficient is introduced. Scaling factor .

[0068] Furthermore, with amplitude The blade and bone begin to experience intermittent, high-frequency separation, which leads to an increase in the average coefficient of friction. Dynamic changes occur In the formula The item then became Let the amplitude coefficient be...

[0069] Furthermore, Jaeger's theory assumes that all heat is transferred to the bone, but in actual grinding, some heat is carried away by bone chips and the tool; the proportion of heat carried away changes with the feed rate. Additionally, the tangential gain generated by the rotational oscillation can be considered as... The linear expansion will cause a certain amount of heat to dissipate, so... The index is set to the undetermined feed index. .

[0070] Furthermore, in biomechanics, the thermal conductivity and specific heat capacity of bone are not constants, but rather nonlinear functions highly dependent on bone density, typically exhibiting a power-law relationship. Therefore, The index is set as the density index to be determined. .

[0071] The temperature theoretical analysis model is summarized and represented as follows:

[0072]

[0073] Based on the above temperature theory analysis model, the relationship between ultrasonic grinding temperature and feed rate, ultrasonic amplitude, and bone density was analyzed, which will serve as the theoretical basis for the construction of the temperature model.

[0074] Step S2: Based on the temperature theory analysis model, establish a finite element analysis model for ultrasonic bone grinding to obtain the influence of bone density, the vibration amplitude of the cylindrical drill of the ultrasonic equipment, and the feed rate on the grinding temperature.

[0075] Specifically, to create a finite element analysis model using Abaqus software, it is necessary to first create a solid geometric model of the component to be analyzed, such as... Figure 3 As shown. In Solidworks 3D CAD software, a solid geometric model of the bone block and cylindrical grinding head is constructed and then imported into Abaqus finite element simulation software.

[0076] Furthermore, a material parameter library for the bone model and cylindrical grinding head is constructed in the attribute module. Density elasticity, specific heat, thermal conductivity, material model, and damage model are set, and values ​​are assigned to the solid geometry model by setting the cross section. The specific settings of density elasticity for the bone model and cylindrical grinding head are shown in Table 1 and Table 2.

[0077] Furthermore, the material model can approximately describe the plastic deformation of materials under high strain rates. By reasonably adjusting the material model parameters, the elastoplastic behavior of bone tissue under high strain rates can be approximately simulated.

[0078] Specifically, the basic formula of the Johnson-Cook material model is:

[0079]

[0080] in, For the initial yield stress, hardening modulus, and strain rate sensitivity coefficient of the material; , and For equivalent plastic strain, equivalent plastic strain rate, and reference plastic strain rate; The strain hardening index; Temperature softening index; For normalized temperature, ,in, The temperature of the bone grinding area; The melting point of the material; The room temperature setting is shown in Table 3.

[0081] Furthermore, a damage model is established to describe the damage evolution of bone materials during the grinding process. Specifically, the basic formula of the Johnson-Cook damage model is:

[0082]

[0083] in, For failure strain; This is a coefficient related to material damage; The normalized strain rate is set as shown in Table 4.

[0084] Furthermore, based on the relative positional relationships in a real grinding scenario, multiple components are instantiated and combined into a complete model within the assembly. The cylindrical grinding head is simplified into a rigid body with a reference point (RP), such as... Figure 4 As shown in (a);

[0085] Furthermore, the bone model and the cylindrical grinding head are meshed. First, as... Figure 4As shown in (b), the bone model was meshed using C3D8T linear eight-node thermally coupled hexahedral elements with a global size of 0.5 mm, resulting in 256,000 cells. The cylindrical drill bit was meshed using C3D4 four-node linear tetrahedral elements with a global size of 0.02 mm, resulting in 71,888 cells. To improve solution accuracy and reduce solution time, a multi-mesh density method was used to mesh the bone model. In this method, the grinding region was meshed using high-density elements, and the local mesh design rules were set to 0.1 mm for both the feed and depth directions. Other regions were meshed using low-density elements.

[0086] Furthermore, grinding contact constraints are set between the bone model and the cylindrical grinding head. For example... Figure 4 As shown in (c), first, rigid body constraints are set on the reference point (RP). Then, the contact properties between the cylindrical grinding head and the bone model are set, including adding tangential behavior, selecting the friction rule as penalty, and setting the friction factor to 0.15; adding normal behavior with default settings; and adding heat generation with default settings. Finally, the grinding contact area between the bone model and the cylindrical grinding head is set.

[0087] Furthermore, the loads on the bone model and the cylindrical grinding head are set. First, as... Figure 4 As shown in (d), the bone model is fixed, and the boundary conditions of the bone model are to constrain the six degrees of freedom of the bottom surface (U1=U2=U3=UR1=UR2=UR3=0), where U1, U2, and U3 are the velocities in the X, Y, and Z directions, respectively, and UR1, UR2, and UR3 are the rotational velocities around the X, Y, and Z axes, all set to 0. Next, different feed rates in the negative X-axis direction, as well as periodic high-frequency simple harmonic vibrations in the radial and axial directions, are applied at the reference point (RP) of the cylindrical grinding head, and simultaneously a low-speed rotational oscillation is applied.

[0088] Based on the above conditions, a dynamic analysis of the complex bone model and cylindrical grinding head dynamics is employed. A schematic diagram of the spatiotemporal distribution from the finite element simulation is shown below. Figure 5 As shown, the grinding temperature during stable grinding was collected.

[0089] Step S3: Based on the finite element analysis model, establish a temperature model for ultrasonic bone grinding and obtain a mathematical characterization of the relationship between grinding temperature and bone density, vibration amplitude and feed rate.

[0090] Based on the above finite element analysis model, multiple sets of simulation experiments were designed, and the data were processed based on the simulation results to fit the model parameters.

[0091] Specifically, simulation experiment design can be divided into the following cases, and the simulation experiment results are as follows: Figure 6 As shown:

[0092] In the first case, under the condition of keeping the bone density and the amplitude of the ultrasonic drill constant, the feed rate is changed, and the grinding temperature at the stable grinding state during the grinding process is taken as the result.

[0093] In the second case, while keeping the bone density and ultrasonic milling feed rate constant, the amplitude of the milling drill is changed, and the grinding temperature at the stable grinding state during the grinding process is taken as the result.

[0094] In the third case, under the condition of keeping the ultrasonic drill amplitude and feed speed constant, the bone density is changed, and the grinding temperature at which the grinding state is stable during the grinding process is taken as the result.

[0095] Furthermore, the final model parameters are determined through constrained nonlinear least squares optimization, including five undetermined parameters in the model. This is determined by solving the following constrained optimization problem:

[0096]

[0097] Furthermore, to ensure the physical rationality and numerical stability of the parameters, strict boundary constraints were imposed on them. The benchmark range was limited based on prior knowledge to prevent overfitting, as shown below:

[0098]

[0099] Specifically, the Levenberg-Marquardt algorithm is used for iterative solution to ensure convergence to a local optimum, and a coefficient of determination is employed. Quantify the goodness of fit of the model to the training data:

[0100]

[0101] in, For the sum of squared residuals, For the total sum of squares, The target quantity is the mean. For real data, For prediction data.

[0102] Furthermore, five undetermined parameters and goodness of fit were obtained, as shown in Table 5.

[0103] Furthermore, based on the above temperature model, physical experiments were conducted to draw safety parameter boundaries and evaluate the accuracy and applicability of the temperature model.

[0104] Specifically, physical experiment design can be divided into the following categories:

[0105] In the first scenario, under the condition of maintaining a constant bone density and ultrasonic drill amplitude, the grinding temperature in a stable grinding state decreases with increasing ultrasonic drill feed rate, such as... Figure 7 As shown;

[0106] In the second scenario, under the condition of maintaining a constant bone density and ultrasonic drill feed rate, the grinding temperature in a stable grinding state increases with the increase of ultrasonic drill amplitude, such as... Figure 8 As shown;

[0107] In the third scenario, under the condition of maintaining a constant ultrasonic drill amplitude and feed rate, the grinding temperature in a stable grinding state increases with increasing bone density, such as... Figure 9 As shown;

[0108] Furthermore, to further verify the accuracy of the temperature model prediction, the results of the physical experiment and the simulation calculations were compared and analyzed.

[0109] The comparison results for Group 1 are as follows Figure 10 As shown in (a), the average grinding temperature was compared at feed rates of 1 mm / s, 2.5 mm / s, and 4 mm / s. The results show that the experimental results are largely consistent with the simulation calculation results, with a maximum error of 1.04℃ and an average error of 0.80℃ in the grinding temperature.

[0110] The comparison results for group 2 are as follows Figure 10 As shown in (b), the ultrasonic amplitude at 60 was compared. 80 100 The average grinding temperature was determined. The results show that the experimental results are largely consistent with the simulation calculation results, with a maximum error of 1.87℃ and an average error of 1.15℃ in grinding temperature.

[0111] The comparison results for group 3 are as follows Figure 10 As shown in (c), the average grinding temperatures at bone mineral density of 480 kg / m³, 800 kg / m³, and 1640 kg / m³ were compared. The results show that the experimental results are largely consistent with the simulation calculation results, with a maximum error of 2.67℃ and an average error of 1.68℃ in the grinding temperature.

[0112] Furthermore, the safe temperature threshold for bone grinding is 47℃. Based on this safety threshold, a temperature model thermogram is plotted to visually observe the safe grinding parameters such as bone density, ultrasonic amplitude, and feed rate. Figure 11 As shown.

[0113] Based on the above temperature model, a mathematical representation of the relationship between grinding temperature, vibration amplitude, and feed rate is obtained, which will serve as the basis for optimizing and controlling the motion parameters of ultrasonic grinding drill bone grinding in robotic arms.

[0114] A second aspect of the present invention provides a temperature model construction device for ultrasonic grinding of bone by a robotic arm, comprising:

[0115] The first processing unit is used to obtain a theoretical temperature analysis model for ultrasonic grinding of bone based on the motion process of ultrasonic grinding.

[0116] The second processing unit is used to establish a finite element analysis model for ultrasonic bone grinding based on the temperature theory analysis model, and to obtain the influence of bone density, the vibration amplitude of the cylindrical drill of the ultrasonic equipment, and the feed rate on the grinding temperature.

[0117] The third processing unit is used to establish a temperature model for ultrasonic bone grinding based on the finite element analysis model, and to obtain a mathematical characterization of the relationship between grinding temperature and bone density, vibration amplitude and feed rate.

[0118] In a third aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, characterized in that, when the computer program is executed by a processor, it implements the steps of the method for constructing a temperature model for ultrasonic grinding of bone by a robotic arm as described in any one of the preceding claims.

[0119] In a fourth aspect, the present invention provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, when the processor executes the computer program, it implements the steps of the method for constructing a temperature model for ultrasonic grinding of bone by a robotic arm as described in any of the above-mentioned methods.

[0120] This invention is described based on flowcharts and / or block diagrams of methods, apparatus (systems), and computer program products according to specific embodiments. It should be understood that each block of the flowcharts and / or block diagrams, and combinations of blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing device to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing device, generate instructions for implementing the flowcharts and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0121] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0122] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0123] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

[0124] Table 1 Physical properties of the bone model

[0125] project numerical values Density (kg / m³) 480-800-1120 Elastic modulus (GPa) 17 Poisson's ratio 0.35

[0126] Table 2 Physical properties of cylindrical grinding heads

[0127] project numerical values Density (kg / m³) 7840 Elastic modulus (GPa) 210 Poisson's ratio 0.3

[0128] Table 3. Main parameters of the Johnson-Cook material model

[0129] project numerical values A 50 B 101 C 0.03 n 0.08 m 1

[0130] Table 4 Parameters of the John-Cook Injury Model

[0131] project numerical values <![CDATA[D1]]> 0.34 <![CDATA[D2]]> -0.272 <![CDATA[D3]]> -0.172 <![CDATA[D4]]> 0.014

[0132] Table 5 Parameter Fitting Results

[0133] project numerical values <![CDATA[C0]]> 42.9660 <![CDATA[C1]]> 9.8402e-07 <![CDATA[C2]]> 2.5758 <![CDATA[C3]]> 0.8707 <![CDATA[C4]]> 0.6746 R² 0.8127

Claims

1. A method for constructing a temperature model for ultrasonic grinding of bone by a robotic arm, characterized in that, The method includes S1. Based on the motion process of ultrasonic grinding, a theoretical temperature analysis model for ultrasonic bone grinding is obtained. S2. Based on the temperature theory analysis model, a finite element analysis model for ultrasonic bone grinding is established to obtain the influence of bone density, the vibration amplitude of the cylindrical drill of the ultrasonic equipment, and the feed rate on the grinding temperature. S3. Based on the finite element analysis model, a temperature model for ultrasonic bone grinding is established to obtain the mathematical characterization of the relationship between grinding temperature and bone density, vibration amplitude and feed rate.

2. The method according to claim 1, characterized in that, Based on the motion process of ultrasonic grinding, a theoretical temperature analysis model for ultrasonic bone grinding is obtained, including: Based on the kinematic characteristics and frictional heat generation principle of ultrasonic grinding, the heat at the grinding interface mainly comes from high-frequency friction. The normal friction force is determined by the grinding force in the feed direction and the friction coefficient. The average heat flux transmitted to the bone tissue is obtained based on the normal friction force, the equivalent cutting speed dominated by ultrasonic vibration, and the contact area between the tool and the bone. Based on the Jaeger moving heat source model, the ultrasonic grinding process is regarded as a moving strip heat source, and the basic relationship between temperature rise and grinding force, amplitude, feed rate and bone density is obtained. Furthermore, considering the dynamic changes of the friction coefficient with amplitude, the change of heat distribution ratio with feed rate, and the nonlinear dependence of bone thermophysical parameters on bone density in actual grinding, undetermined coefficients are introduced. Based on the above temperature theory analysis model, the relationship between ultrasonic grinding temperature and feed rate, ultrasonic amplitude, and bone density was analyzed, which will serve as the theoretical basis for the construction of the temperature model.

3. The method for theoretical temperature analysis of ultrasonic bone grinding according to claim 2, characterized in that, The specific temperature theoretical analysis model is as follows: In the formula, It's the grinding temperature. It's bone density. This refers to the amplitude of the ultrasonic drill. For feed rate, It is the grinding force in the feed direction obtained by the surface response method. These are the bias coefficient, scaling coefficient, amplitude coefficient, feed index, and density index.

4. The method according to claim 1, characterized in that, Based on the temperature theory analysis model, a finite element analysis model for ultrasonic bone grinding is established to obtain the influence of bone density, the vibration amplitude of the cylindrical drill of the ultrasonic equipment, and the feed rate on the grinding temperature, including: Solid geometric models of the cylindrical drill and bone were constructed using 3D modeling software, and the generated solid geometric models were imported into finite element simulation software. Based on the inherent material properties of the bone model and the cylindrical grinding head, the density elasticity, material model, damage model, specific heat, and thermal conductivity of the bone model and the cylindrical grinding head are constructed. Based on the relative positional relationships in a real grinding scenario, multiple components are instantiated and combined into a complete model in the assembly. Among them, the cylindrical grinding head is simplified into a rigid body with a reference point. Based on the geometric features, material properties, analysis step size, and thermodynamic characteristics of the finite element model, a precise layered mesh is created for the bone model and the cylindrical grinding head. Based on the bone grinding process in a real grinding scenario, the bottom surface of the bone model is constrained and fixed to simulate the fixed support effect under real conditions; the interaction between the bone model and the cylindrical grinding head is constructed, and the contact type, contact properties, heat generation and constraints between the bone model and the cylindrical grinding head are set. Based on the actual bone grinding process, the load parameters of the finite element model are set to simulate the bone grinding motion process of the ultrasonic drill. Based on the above conditions, the thermodynamic behavior of the bone model and the cylindrical grinding head was analyzed using the explicit dynamic temperature displacement analysis method. By analyzing the average grinding temperature of the stable grinding process in multiple sets of simulation results, it was found that the grinding temperature increases with the increase of bone density; the grinding temperature increases with the increase of ultrasonic amplitude of the cylindrical grinding head of the robotic arm; and the grinding temperature decreases with the increase of feed speed of the cylindrical grinding head of the robotic arm. Based on the above finite element analysis model, data on the grinding temperature in the feed direction under different bone densities, ultrasonic amplitudes, and feed speeds were collected to provide data support for the temperature model.

5. The method for constructing a mechanical model for ultrasonic drilling and bone grinding by a robotic arm according to claim 4, characterized in that, The calculation formulas for the material model are as follows: in, It is flow stress. For the initial yield stress, hardening modulus, and strain rate sensitivity coefficient of the material; , and For equivalent plastic strain, equivalent plastic strain rate, and reference plastic strain rate; The strain hardening index; Temperature softening index; For normalized temperature, ,in, The temperature of the bone grinding area; The melting point of the material; Room temperature; Furthermore, a damage model is established to describe the damage evolution of bone materials during the grinding process. Specifically, the basic formula of the Johnson-Cook damage model is: in, For failure strain; This is a coefficient related to material damage; To normalize the strain rate, It is stress triaxiality.

6. The method according to claim 1, characterized in that, Based on the finite element analysis model, a temperature model for ultrasonic bone grinding is established to obtain a mathematical characterization of the relationship between grinding temperature and bone density, vibration amplitude, and feed rate, including: Based on the above finite element analysis model, multiple sets of simulation experiments were designed, and the data were processed based on the simulation results to fit the model parameters. Based on the above temperature model, conduct physical experiments, draw safety parameter boundaries, and evaluate the accuracy and applicability of the temperature model; Based on the above temperature model, a mathematical representation of the relationship between grinding temperature, vibration amplitude, and feed rate is obtained, which will serve as the basis for optimizing and controlling the motion parameters of ultrasonic grinding drill bone grinding in robotic arms.

7. A temperature model construction device for ultrasonic grinding of bone by a robotic arm, characterized in that, include: The first processing unit is used to obtain a theoretical temperature analysis model for ultrasonic grinding of bone based on the motion process of ultrasonic grinding. The second processing unit is used to establish a finite element analysis model for ultrasonic bone grinding based on the temperature theory analysis model, and to obtain the influence of bone density, the vibration amplitude of the cylindrical drill of the ultrasonic equipment, and the feed rate on the grinding temperature. The third processing unit is used to establish a temperature model for ultrasonic bone grinding based on the finite element analysis model, and to obtain a mathematical characterization of the relationship between grinding temperature and bone density, vibration amplitude and feed rate.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the method for constructing a temperature model for ultrasonic grinding of bone by a robotic arm as described in any one of claims 1-6.

9. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method for constructing a temperature model for ultrasonic grinding of bone by a robotic arm according to any one of claims 1-6.

Images