A method for constructing a mechanical model of robot-assisted kirschner wire drilling

Abstract

The application provides a kind of robot-assisted kirschner wire bone drilling mechanics model construction method, comprising: analyzing the process of robot-assisted kirschner wire bone drilling, obtaining the geometric model of mechanical analysis of robot-assisted kirschner wire bone drilling;According to the geometric model of mechanical analysis, a kind of finite element analysis model of robot-assisted kirschner wire bone drilling is established, the influence law of kirschner wire rotating speed, feed speed, the relative angle between kirschner wire and bone surface on drilling force is obtained;According to the data of mechanical analysis geometric model and finite element model, a kind of mechanical model of robot-assisted kirschner wire placement is established, and the mathematical representation between drilling force and kirschner wire rotating speed, feed speed, the angle between kirschner wire and bone surface is obtained.According to the technical scheme provided by the application, the construction of the mechanical model of robot-assisted kirschner wire bone drilling can be realized.

Description

TECHNICAL FIELD

[0001] The application relates to a robot-assisted Kirschner wire bone drilling mechanics model construction method and belongs to the field of robot bone drilling. BACKGROUND

[0002] In orthopedic surgery, using a Kirschner wire to drill a hole in a bone is a common clinical operation. Due to the complexity of the bone surface structure, the Kirschner wire is often at an angle to the bone surface when drilling, and this inclined drilling process is prone to slipping, which makes it difficult for the Kirschner wire to accurately enter the intended position, and thus the surgeon needs to frequently adjust the drilling site during the operation. To solve this problem, establishing a Kirschner wire bone drilling mechanics model has important value for predicting the deflection force generated by the inclined placement of the guide needle when slipping, and can provide a theoretical basis for slip correction.

[0003] Drilling force can be constructed by theoretical modeling and empirical analysis. Theoretical modeling obtains the integral form of drilling force by the micro-geometric structure, motion state and stress of the Kirschner wire, but this method ignores the characteristics of different bone structures, making it difficult to visually show the relationship between drilling force and drilling parameters such as feed speed, rotation speed and inclination angle, and it is difficult to be directly applied to actual robot control. Empirical analysis method establishes an empirical formula or regression model between drilling force and parameters such as feed speed, rotation speed and inclination angle through a large amount of experimental data. However, the limitation of empirical analysis method is the lack of deep understanding of the micro-physical process, making it difficult to explain the fundamental mechanism of drilling force. In summary, it is of great significance to develop a robot-assisted Kirschner wire bone drilling mechanics model construction method. SUMMARY

[0004] Therefore, the application provides a robot bone drilling mechanics model construction method to realize the mechanical modeling of robot bone drilling.

[0005] The application provides a robot bone drilling mechanics model construction method, which comprises the following steps:

[0006] The process of robot-assisted Kirschner wire bone drilling is analyzed to obtain a mechanical analysis geometric model of robot-assisted Kirschner wire bone drilling.

[0007] According to the mechanical analysis model of Kirschner wire bone drilling, the resultant force of Kirschner wire bone drilling can be decomposed into a radial component , a tangential component and an axial component , wherein the axial force is generated by the mechanical arm feed and is responsible for maintaining the Kirschner wire feed; the tangential component is generated by the rotation of the Kirschner wire and acts as a cutting force to cut the bone tissue; and the radial component is generated by the insufficient contact between the Kirschner wire tip and the bone tissue, which will cause the slipping phenomenon in the initial placement of the guide needle.

[0008] According to the mechanical analysis geometric model, a finite element analysis model of robot-assisted Kirschner wire bone drilling is established, and the influence of Kirschner wire speed, feed speed, and the relative angle between Kirschner wire and bone surface on drilling force is obtained.

[0009] According to the mechanical analysis geometric model and finite element model data, a mechanical model of robot-assisted Kirschner wire bone drilling is established, and the mathematical representation between drilling force and Kirschner wire speed, feed speed, and the relative angle between Kirschner wire and bone surface is obtained.

[0010] In the above method, the finite element analysis model of robot-assisted Kirschner wire bone drilling is established according to the mechanical analysis geometric model, and the influence of Kirschner wire speed, feed speed, and the relative angle between Kirschner wire and bone surface on drilling force is obtained, including:

[0011] According to the mechanical analysis geometric model of robot bone grinding, a three-dimensional modeling software is used to construct the solid geometric model of Kirschner wire and femur, and the generated model is imported into the finite element simulation software. In the assembly, the relative position of the femur model and the Kirschner wire model is set.

[0012] According to the material nature attribute of the femur model and the Kirschner wire model, the material attribute and constitutive model of the femur model and the Kirschner wire model are constructed.

[0013] According to the geometry and stress state of the simulation model, a multi-density grid structure of the femur model and the Kirschner wire model is constructed.

[0014] According to the actual bone drilling state, the drilling contact constraints of the Kirschner wire and the femur model are set respectively, wherein the Kirschner wire is regarded as a rigid body with a reference point (RP); the bottom surface of the femur model is fixed to realize the modeling of the actual scene of robot bone drilling.

[0015] According to the above condition setting, the complex Kirschner wire and femur dynamics behavior is analyzed by using explicit dynamics, the radial force of the Kirschner wire is collected , and the trend of the radial force is observed. The result shows that the radial force increases first and then decreases with time, and the maximum value increases with the increase of the angle between the Kirschner wire and the bone.

[0016] According to the above finite element analysis model, drilling radial force data under different spindle speeds, different feed speeds, and different inclination angles between Kirschner wire and bone surface are collected to provide sufficient experimental data.

[0017] In the above method, the mechanical model of robot-assisted Kirschner wire bone drilling is established according to the mechanical analysis geometric model and finite element model data, and the mathematical representation between drilling force and Kirschner wire speed, feed speed, and the relative angle between Kirschner wire and bone surface is obtained, including:

[0018] According to the mechanical analysis model of the Kirschner wire bone drilling, the resultant force of the Kirschner wire bone drilling can be decomposed into a radial component , a tangential component , and an axial component The axial force is generated by the mechanical arm feeding and is responsible for maintaining the Kirschner wire feeding; the tangential component is generated by the Kirschner wire rotation and serves as the cutting force to cut the bone tissue; and the radial component is generated by the insufficient contact between the Kirschner wire tip and the bone tissue and will cause the needle placement to slip in the initial stage.

[0019] According to the relationship between the drilling force and the spindle speed, the feeding speed, and the inclination angle, and the finite element simulation data, a mechanical model is established by using the response surface method, which serves as the basis for the optimization and control of the robot bone drilling motion parameters.

[0020] As can be seen from the above technical solution, the present application has the following beneficial effects:

[0021] In the technical solution of the present application, a mechanical analysis geometric model of robot bone drilling is obtained; according to the mechanical analysis geometric model, a finite element analysis model of robot bone drilling is established to obtain the influence law of the spindle speed and the feeding speed of the Kirschner wire and the relative angle between the Kirschner wire and the femur on the grinding force; according to the mechanical analysis geometric model and the finite element model data, a mechanical model of robot bone drilling is established to obtain the mathematical representation between the radial force borne by the Kirschner wire and the spindle speed, the feeding speed, and the angle between the Kirschner wire and the bone, which provides a model basis for the Kirschner wire slip control of the robot drilling and at the same time provides a theoretical basis for the research of the robot bone drilling system. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creativity and labor.

[0023] Figure 1 is a flowchart of the method for constructing the force model of robot bone drilling provided by the present application;

[0024] Figure 2 is a schematic diagram of a bone grinding robot system provided in the present application;

[0025] Figure 3 is a schematic diagram of a mechanical analysis geometric model provided in the embodiments of the present application;

[0026] Figure 4is a finite element analysis schematic diagram provided in the embodiment of the present application: (a) a three-dimensional model of bone; (b) a three-dimensional model of the Kirschner wire; (c) a mesh of the bone; (d) a mesh of the Kirschner wire; (e) a load constraint of the bone; (f) a load constraint of the Kirschner wire;

[0027] Figure 5 is a space-time distribution schematic diagram of finite element simulation provided in the embodiment of the present application: (a) a non-placed state; (b) a partially placed state; (c) a stable placed state;

[0028] Figure 6 is a response surface plot of the grinding mechanics model provided in the embodiment of the present application;

[0029] Figure 7 is a schematic diagram of the radial force of the Kirschner wire varying with time under different feed speeds in the finite element simulation provided in the embodiment of the present application;

[0030] Figure 8 is a schematic diagram of the radial force of the Kirschner wire varying with time under different spindle speeds in the finite element simulation provided in the embodiment of the present application;

[0031] Figure 9 is a schematic diagram of the radial force of the Kirschner wire varying with time under different inclination angles in the finite element simulation provided in the embodiment of the present application;

[0032] Figure 10 is a residual analysis diagram provided in the embodiment of the present application. Specific embodiments

[0033] In order to better understand the technical solutions of the present application, the embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0034] It should be clear that the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor belong to the scope of protection of the present application.

[0035] The embodiment of the present application provides a method for constructing a mechanical model of robot bone drilling, please refer to Figure 1 , which is a flowchart of the method for constructing a force model of robot drilling provided by the present application, as shown in Figure 1 , without being limited to the foregoing, the method for constructing a mechanical model of robot bone drilling is applicable to the field of orthopedic surgery, and provides a radial contact force output model for robot bone drilling in the surgical operation process, so as to more accurately control the robot parameters to make the radial force of bone drilling within a certain range, thereby reducing the generation of slip phenomenon when the robot autonomously drills the bone, and improving the accuracy of bone drilling. The method comprises the following steps:

[0036] Step 101, analyze the process of robot bone drilling, and establish a mechanical analysis geometric model of robot bone drilling;

[0037] Reference Figure 2 The bone grinding robot system 201 includes a mechanical arm 202, a six-dimensional force sensor 213, a high-speed grinding drill 215, and a Kirschner wire 216. The bone grinding robot system 201 can be arranged to drill autonomously. What the bone grinding robot system 201 provides is the autonomous movement of fully controlling the mechanical arm 202, the high-speed grinding drill 215, and the Kirschner wire 216 device, while the grinding force collected by the six-dimensional force sensor 213 is used as a feedback signal.

[0038] The mechanical arm 202 is a six-degree-of-freedom mechanical arm, including a base flange 203, a rotation 1 joint 204, a rotation 2 joint 205, a 1 connecting rod 206, a rotation 3 joint 207, a 2 connecting rod 208, a rotation 4 joint 209, a rotation 5 joint 210, a rotation 6 joint 211, and a terminal flange 212. The six-dimensional force sensor 213 is fixedly installed on the terminal flange 212, the high-speed grinding drill fixing part 214 is fixedly installed on the six-dimensional force sensor 213, the high-speed grinding drill 215 is fixedly installed on the high-speed grinding drill fixing part 214, and the Kirschner wire 216 is fixedly installed at the end of the high-speed grinding drill 215.

[0039] Specifically, the process of robot bone drilling is analyzed, and reference is made to Figure 3 The Kirschner wire X-axis, Y-axis, and Z-axis are constructed, the Z-axis is the Kirschner wire axial direction, the negative direction of the Z-axis is the feed direction, the Y-axis is perpendicular to the Z-axis direction, and the X-axis satisfies the right-hand screw rule and is perpendicular to the Y-axis and the Z-axis.

[0040] According to the coordinate axes of the robot bone grinding process, a mechanical analysis geometric model of robot bone grinding is constructed, as shown in Figure 3 The axial drilling force of the Kirschner wire along the Z-axis direction The radial drilling force of the Kirschner wire along the Y-axis direction The circumferential drilling force of the Kirschner wire The angle between the Kirschner wire and the bone surface The spindle speed of the Kirschner wire The feed speed of the Kirschner wire The diameter of the Kirschner wire The length of the Kirschner wire drill edge The cutting half-angle of the Kirschner wire .

[0041] Step 102, according to the mechanical analysis geometric model, a finite element analysis model of robot-assisted Kirschner wire bone drilling is established to obtain the influence law of Kirschner wire speed, feed speed, and the relative angle between the Kirschner wire and the bone surface on the drilling force;

[0042] Specifically, according to the mechanical analysis model of the robot bone drill, a Kirschner pin geometric model is constructed by using Solidworks three-dimensional modeling software, and a bone model is constructed by using ITK-snap software, as shown in Figs. Figure 4 (a), Figure 4 (b). Both are imported into Abaqus finite element simulation software, and the relative position between the bone model and the Kirschner pin is set in the assembly, and the angle between them is .

[0043] Further, the material properties and constitutive model of the bone model and the Kirschner pin are set. The Kirschner pin contacts the cortical bone during drilling, and the material properties of the cortical bone are: the density is 1640 kg / m 3 , the elastic modulus is 17 GPa, and the Poisson's ratio is 0.35, as shown in Table 1. The material of the Kirschner pin is TC4 titanium alloy, and the properties are: the density is 8640 kg / m 3 , the elastic modulus is 210 GPa, and the Poisson's ratio is 0.3, as shown in Table 2.

[0044] The constitutive model establishes the stress and strain relationship in the grinding area, which can predict the stress distribution and strain accumulation in the grinding area, and is a key factor in finite element analysis.

[0045] According to the Johnson-Cook material model, as shown in the following formula,

[0046]

[0047] In the formula, is the equivalent flow stress, is the equivalent plastic strain; and are the equivalent plastic strain rate and the reference plastic strain rate; is the temperature of the bone grinding site; is the melting point of the material; is the room temperature; is the strain hardening index; is the thermal softening index; is the yield strength, strain and strain sensitivity rate of the material, and the strain parameters of the bone model are designed as shown in Table 3.

[0048] According to the Johnson-Cook damage model, as shown in the following formula,

[0049]

[0050] In the formula, is the equivalent strain when the material is damaged, is the damage coefficient related to quasi-static damage, The coefficients are related to the effect of strain rate, and the bone model damage parameters are designed, as shown in Table 4.

[0051] Next, the multi-density network structure of the bone model and the Kirschner wire is set. As shown in Figure 4 (c) and Figure 4 (d) shown, the bone model is meshed using C3D4 type linear eight-node hexahedral elements, the seed point setting size is 1.2, and the model is divided into 407251 unit cells. The Kirschner wire is meshed using C3D10M type quadratic tetrahedral elements, the seed point setting size is 0.5, and it is divided into 19576 unit cells.

[0052] Next, the drilling contact constraint of the bone model and the Kirschner wire is set. As shown in Figure 4 (e) and Figure 4 (f) shown, in the bone drilling simulation, the bone model is fixed, the boundary conditions of the bone model are six degrees of freedom of the bottom surface (U1=U2=U3=UR1=UR2=UR3=0), where U1, U2, U3 are the velocities in XYZ directions, UR1, UR2, UR3 are the rotational velocities around XYZ axes, all set to 0, and the Kirschner wire needs to complete drilling, including rotation around the axis and feeding along the axis, different feeding speeds in the negative direction of the Z axis and different spindle speeds in the Z axis direction are applied at the reference point of the Kirschner wire, to ensure the simulation of the actual bone drilling scene.

[0053] According to the above condition setting, the explicit dynamics analysis is used to analyze the complex dynamic behavior of the interaction between the Kirschner wire and the bone. The entire bone drilling process is divided into three stages: not placed, partially placed and completely placed, and each stage is analyzed, as shown in Figure 5 , and the axial drilling force ( of the Kirschner wire is collected.

[0054] Step 103, according to the mechanical analysis geometric model and the finite element model data, a mechanical model of robot-assisted Kirschner wire bone drilling is established by using the response surface analysis method, and the mathematical representation between the drilling force and the Kirschner wire speed, the feeding speed, the relative angle between the Kirschner wire and the bone surface is obtained.

[0055] According to the relationship between the drilling force and the spindle speed, the feeding speed and the inclination angle, and the finite element simulation data, a mechanical model is established by using the response surface method, as shown in Figure 6 , which will be the basis for optimization and control of robot bone drilling motion parameters.

[0056] According to the response surface analysis method, first, the sequential model sum of squares analysis is performed, and the results of the sequential model sum of squares analysis are shown in Table 5. The The values are 0.0300, 0.4928 and 0.0335, respectively. Among them, the value of the linear model is significantly less than 0.05, indicating that the linear model has a strong explanatory ability for the data. The value of the second-order interaction model is not significant (greater than 0.05), while the value of the quadratic model is significant, indicating that the quadratic model has a better fitting effect than the linear model and the second-order interaction model. The value of the second-order interaction model is not significant (greater than 0.05), while the value of the quadratic model is significant, indicating that the quadratic model has a better fitting effect than the linear model and the second-order interaction model. The value of the second-order interaction model is not significant (greater than 0.05), while the value of the quadratic model is significant, indicating that the quadratic model has a better fitting effect than the linear model and the second-order interaction model. The value of the cubic model is 0.7937, indicating that the high-order term of the cubic model does not contribute significantly to the model, and the cubic model has confusion problems, so it is not used.

[0057] Next, the residual term analysis is performed, and the residual term analysis results are shown in Table 6. The residual term values of the linear model and the second-order interaction model are 0.3702 and 0.3409, respectively, both of which are greater than 0.05, indicating that the residual terms are not significant. However, the residual term value of the quadratic model is 0.7937, further verifying its high fitting with the experimental data. The residual term values of the linear model and the second-order interaction model are 0.3702 and 0.3409, respectively, both of which are greater than 0.05, indicating that the residual terms are not significant. However, the residual term value of the quadratic model is 0.7937, further verifying its high fitting with the experimental data. The residual term values of the linear model and the second-order interaction model are 0.3702 and 0.3409, respectively, both of which are greater than 0.05, indicating that the residual terms are not significant. However, the residual term value of the quadratic model is 0.7937, further verifying its high fitting with the experimental data.

[0058] Based on the sequential model sum of squares, residual term analysis and model summary statistics, the quadratic model is selected as the optimal model. The model regression equation is obtained as follows:

[0059]

[0060] Among them, respectively represent the angle between the Kirschner wire and the bone surface, and the coding factor of the Kirschner wire rotation speed and the Kirschner wire feed speed.

[0061] Further evaluate the effectiveness of the model, conduct physical experiments, change different parameters to collect force signals during drilling, and observe the changes of the maximum radial drilling force under different parameters.

[0062] The first case, under the condition of keeping the Kirschner wire angle and spindle speed constant, the radial drilling force of Y-axis increases with the increase of Kirschner wire feed speed, as shown in Figure 7 .

[0063] The second case, under the condition of keeping the Kirschner wire angle and feed speed constant, the radial drilling force of Y-axis decreases with the increase of Kirschner wire rotation speed, as shown in Figure 8 .

[0064] The third case, under the condition of keeping the spindle speed and feed speed constant, the radial drilling force of Y-axis increases with the decrease of Kirschner wire angle, as shown in Figure 9 .

[0065] External studentized residuals were used to evaluate the bone drilling mechanics model. The formula for calculating the external studentized residuals is as follows:

[0066]

[0067] in, It is the first The ordinary residuals of each observation, i.e. ; To exclude the first After 1000 observations, the standard deviation of the residuals of the remaining observations in the model is calculated as follows:

[0068]

[0069] in It is the total number of observations. It is the number of independent variables in the model. Is it excluding the first After the nth observation The residuals of each observation; For the model's first The leverage value of each observation.

[0070] The biochemical residuals of 15 repeated experiments are as follows Figure 10 As shown, the residuals are randomly distributed within the actual value range of the response variable without a clear trend, indicating that the model does not have significant heteroscedasticity or nonlinearity. Furthermore, the absolute values ​​of all residuals are less than 2, indicating that there are no significant outliers. The bone drilling mechanics model has a good fit.

[0071] Table 1 Physical properties of bone

[0072] Item Value Density (kg / m³) 1640 Elastic modulus (GPa) 17 Poisson's ratio 0.35

[0073] Table 2 Physical properties of spherical grinding heads

[0074] Item Value Density (kg / m³) 7840 Elastic modulus (GPa) 210 Poisson's ratio 0.3 Cutter diameter (mm) 5

[0075] Table 3. Main parameters of the Johnson-Cook material model

[0076] Item Value A 50 B 101 C 0.03 n 0.08 m 1

[0077] Table 4 Parameters of the John-Cook Injury Model

[0078] Item Value [D1] 0.34 [D2] -0.272 [D3] -0.172 [D4] 0.014

[0079] Table 5 Results of the sequential model sum of squares analysis

[0080] Source Sum of squares Degrees of freedom Mean square F value P value Linear model 3.05 3 1.02 4.34 0.0300 Second-order interaction model 2151.56 3 0.21 0.88 0.4928 Quadratic model 1.55 3 0.52 6.69 0.0335 Cubic model 0.13 3 0.045 0.36 0.7937 Residual 0.25 2 0.13 - -

[0081] Table 6 Results of the Assay of the Disqualification Items

[0082] Source Sum of squares Degrees of freedom Mean square F value P value Linear model 2.32 6 0.26 4.34 0.0300 Second-order interaction model 1.69 9 0.28 0.88 0.4928 Quadratic model 0.13 3 0.045 6.69 0.0335 Cubic model - - - - - Residual 0.25 2 0.13 - -

Claims

1. A method for constructing a mechanical model of robot-assisted Kirschner wire drilling, characterized in that, The method comprises: The process of robot-assisted Kirschner wire drilling is analyzed, and a mechanical analysis geometric model of robot-assisted Kirschner wire drilling is established; According to the mechanical analysis geometric model, a finite element analysis model of robot-assisted Kirschner wire drilling is established, and the influence law of the Kirschner wire spindle speed, the Kirschner wire feed speed and the relative angle between the Kirschner wire and the bone surface on the drilling force is obtained; According to the mechanical analysis geometric model and the finite element analysis model data, a mechanical model of robot-assisted Kirschner wire drilling is constructed by using the response surface analysis method, and the mathematical representation between the radial drilling force of the bone drilling and the Kirschner wire spindle speed, the feed speed and the relative angle between the Kirschner wire and the bone surface is obtained, including: According to the mechanical analysis model of the Kirschner wire drilling, the resultant force of the Kirschner wire drilling is decomposed into: radial component F R , tangential component F P , and axial component F Q , wherein the axial component is generated by the mechanical arm feeding and is responsible for maintaining the Kirschner wire feeding; the tangential component is generated by the Kirschner wire rotation and serves as the cutting force to cut the bone tissue; and the radial component is generated by the insufficient contact between the Kirschner wire tip and the bone tissue and will cause the sliding phenomenon in the initial stage of the needle placement; According to the relationship among the radial drilling force, the Kirschner wire spindle speed, the Kirschner wire feed speed and the relative angle between the Kirschner wire and the bone surface, and the finite element simulation data, the mechanical model is established by using the response surface method, and the model regression equation is obtained as follows: Wherein A, B and C respectively represent the coding factors of the relative angle between the Kirschner wire and the bone surface, the Kirschner wire spindle speed and the Kirschner wire feed speed.

2. The method of claim 1, wherein, The process of robot-assisted Kirschner wire drilling is analyzed, and a mechanical analysis geometric model of robot-assisted Kirschner wire drilling is established, including: The process of robot-assisted Kirschner wire drilling is analyzed, and a mechanical analysis geometric model of robot-assisted Kirschner wire drilling is established, including: Based on the coordinate axes of the robot-assisted Kirschner wire bone drilling process, a mechanical analysis geometric model of robot-assisted Kirschner wire bone drilling is constructed, including the resultant force F on the Kirschner wire during inclined drilling and the axial component F of the Kirschner wire along the feed direction. Q Radial component F R Tangential component F P The relative angle θ between the Kirschner wire and the bone surface, the spindle speed n, the feed rate f, the diameter d, and the cutting half angle k of the Kirschner wire. a s per revolution, w for Kirschner wire diameter projection, l1 and l2 for the cutting edge length of the Kirschner wire portion; radial force component F R tangential force component F P as shown in the following equation: The process of robot-assisted Kirschner wire drilling is analyzed, and a mechanical analysis geometric model of robot-assisted Kirschner wire drilling is established, including: 。 3. The method of claim 1, wherein, According to the mechanical analysis geometric model, a finite element analysis model of robot-assisted Kirschner wire drilling is established, and the influence law of the Kirschner wire spindle speed, the Kirschner wire feed speed and the relative angle between the Kirschner wire and the bone surface on the drilling force is obtained, including: According to the mechanical analysis geometric model, a finite element analysis model of robot-assisted Kirschner wire drilling is established, and the influence law of the Kirschner wire spindle speed, the Kirschner wire feed speed and the relative angle between the Kirschner wire and the bone surface on the drilling force is obtained, including: According to the mechanical analysis geometric model, a finite element analysis model of robot-assisted Kirschner wire drilling is established, and the influence law of the Kirschner wire spindle speed, the Kirschner wire feed speed and the relative angle between the Kirschner wire and the bone surface on the drilling force is obtained, including: According to the actual Kirschner wire insertion state, the interaction between the femur model and the Kirschner wire model is constructed, and the drilling contact constraint between the Kirschner wire and the femur model is set, wherein the Kirschner wire model is regarded as a rigid body bound with a reference point, and the motion law of the Kirschner wire model is the same as that of the reference point; the femur model is set with a fixed constraint, so as to realize the modeling of the actual scene of robot-assisted Kirschner wire insertion; The explicit dynamic analysis function provided by the Abaqus software is used to analyze the dynamic interaction behavior of the Kirschner wire model and the femur model in the drilling environment, and the radial force suffered by the Kirschner wire in the drilling process is collected and the signal is analyzed; According to the finite element analysis model, the radial drilling force data under different spindle speeds, feed speeds and relative angles between the Kirschner wire and the femur is collected, so as to provide data support for the mechanical model. ​

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