A trigger type probe calibration method of a three-dimensional five-axis machine tool

Abstract

The application discloses a kind of three-dimensional five-axis machine tool trigger type probe calibration method, it includes the following steps: driving the C-axis of three-dimensional five-axis machine tool to drive standard ball rotation, and record the space coordinate value of trigger type probe ball center;Drive three-dimensional five-axis machine tool to carry out interpolation motion, to drive trigger type probe along the preset circular trajectory motion, and record the space coordinate value of trigger type probe ball center;Based on space coordinate value, spherical surface fitting is carried out to obtain standard ball model;Based on the ball center of standard ball model, pre-stroke-directionality model is established, and space coordinate value is corrected;Based on the mapping relationship of corrected space coordinate value measurement coordinates to machine coordinates, to complete calibration.The application can correct the space coordinate value in data set by pre-stroke-directionality model, to correct the directionality deviation when trigger type probe triggers sampling, to obtain accurate mapping relationship of measurement coordinates to machine coordinates.

Description

Technical Field

[0001] This invention belongs to the field of intelligent manufacturing technology, specifically relating to a trigger-type probe calibration method for a three-dimensional five-axis machine tool. Background Technology

[0002] In 3D five-axis machine tools, trigger probes are often used in conjunction with high-precision standard balls to complete calibration. This is used to quickly establish the relative position of the probe ball center (TSP) / tool center point (TCP) and to compensate for errors. The quality of probe calibration directly affects automatic alignment and machining accuracy.

[0003] Furthermore, trigger-type probes exhibit significant pre-travel and directional errors, which vary with the incident normal. Existing probe calibration methods generally employ static compensation. This method, with the probe stationary, calculates the average trigger displacement (i.e., effective radius length) of the probe on the ideal sphere by contacting a standard sphere and recording the probe's trigger point, and uses this as a fixed compensation value. In subsequent measurements, the system superimposes this compensation value onto the coordinates of each direction to correct the deviation between the probe center (TSP) and the tool center point (TCP).

[0004] However, this static compensation method is based only on static triggering results in one or a few directions, assuming that the probe's pre-travel is consistent in all directions. In reality, the internal triggering structure of a trigger-type probe (such as lever-type, strain gauge-type, photoelectric type, etc.) is mechanical, and its triggering threshold is closely related to factors such as the probe's incident direction, contact speed, elastic deformation, and signal delay. The pre-travel under different incident directions actually varies significantly. Therefore, the above static compensation method cannot reflect the coupling error between directionality and dynamic response.

[0005] Especially when the probe is used in a 3D five-axis machine tool, the probe's incident angle changes frequently and its posture is diverse. A single static compensation value will lead to the accumulation of systematic errors, seriously affecting the accuracy of sphere center fitting and subsequent automatic machine tool alignment. Therefore, traditional static compensation methods are not suitable for the integrated dynamic calibration of trigger-type probes. Summary of the Invention

[0006] To address the issues of lateral deviation or vibration in existing slider technologies, this invention provides a method for calibrating a trigger-type probe for a three-dimensional five-axis machine tool. This method constructs a pre-stroke-directionality model based on the center of a standard spherical model. This model is used to correct each spatial coordinate value in the dataset, thereby correcting the directional deviation of the trigger-type probe when it triggers sampling under different incident directions and postures. This results in a precise mapping relationship between the measured coordinates and the machine tool coordinates, significantly improving the automatic alignment and machining accuracy of the three-dimensional five-axis machine tool.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A method for calibrating a trigger-type probe for a three-dimensional five-axis machine tool is provided, comprising the following steps:

[0009] Lock the XYZ axes of the three-dimensional five-axis machine tool and drive the C axis of the three-dimensional five-axis machine tool to rotate the standard ball. Control the trigger probe to move toward the standard ball with the same first starting angle and first feed speed each time, so that the trigger probe makes point contact with N sampling points on the surface of the standard ball in sequence, and record the spatial coordinate value of the center of the ball of the trigger probe in the machine tool coordinate system at each point contact.

[0010] The Z-axis and C-axis of the three-dimensional five-axis machine tool are locked, and the X-axis and Y-axis of the three-dimensional five-axis machine tool are driven to perform interpolation motion, so as to drive the trigger probe to move along a preset circular trajectory around the standard sphere. Each time the trigger probe is located at a predetermined point on the preset circular trajectory, the three-dimensional five-axis machine tool drives the trigger probe to move towards the standard sphere with the same second starting angle and second feed speed, so that the trigger probe makes point contact with M sampling points on the surface of the standard sphere in sequence, and records the spatial coordinate value of the center of the sphere of the trigger probe in the machine tool coordinate system at each point contact.

[0011] The spatial coordinates of the center of all the trigger probes in the machine tool coordinate system are merged into a dataset, and a spherical fit is performed based on the spatial coordinates in the dataset to obtain a standard sphere model, and the center of the standard sphere model is calculated.

[0012] A pre-travel-directionism model is established based on the center of the standard sphere model, and each spatial coordinate value in the dataset is corrected based on the pre-travel-directionism model to obtain the corrected spatial coordinate values;

[0013] The mapping relationship between the measurement coordinates and the machine tool coordinates is established based on the corrected spatial coordinate values ​​in order to complete the calibration.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] The invention first samples the ball using a trigger probe in two modes, and then performs spherical fitting based on the spatial coordinates of the ball's center obtained from the trigger probe in both modes, in order to correct the position of the standard ball's center and improve the accuracy of subsequent spatial coordinate correction.

[0016] Furthermore, this invention constructs a pre-stroke-directivity model based on the center of a standard sphere model. This model is used to correct each spatial coordinate value in the dataset, thereby correcting the directional deviation of the trigger probe when it triggers sampling under different incident directions and postures. Finally, a precise mapping relationship between the measurement coordinates and the machine tool coordinates can be obtained. Based on this mapping relationship, the automatic alignment and machining accuracy of the three-dimensional five-axis machine tool can be significantly improved. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating the steps of the trigger-type probe calibration method in this invention. Figure 2 This is a diagram showing the installation status of the three-dimensional five-axis machine tool, the standard ball, and the trigger probe in this invention. Figure 3 This is a schematic diagram of the starting angle of the trigger-type probe in this invention; Figure 4 The ellipse is fitted to the motion trajectory in this invention; Figure 5 The circular fitted motion trajectory generated in this invention;

[0018] Figure 6 This is the standard sphere model obtained through spherical fitting in this invention. Detailed Implementation

[0019] 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.

[0020] Example 1:

[0021] like Figure 1 As shown, this embodiment provides a method for calibrating a trigger-type probe for a three-dimensional five-axis machine tool, which includes the following steps:

[0022] S1, such as Figure 2 As shown, a standard ball 1 is mounted on the spindle of a 3D five-axis machine tool 100, and a trigger probe 2 is connected to the 3D five-axis machine tool 100. It is ensured that the surface of the standard ball 1 is free of scratches and oil stains. Simultaneously, the trigger probe 2 performs a self-test, ensuring repeatability ≤1 µm. In this embodiment, the roundness of the standard ball 1 is ≤1 µm, and the spindle direction of the 3D five-axis machine tool 100 is the Z-axis. In this embodiment, the trigger probe 2 has a spherical structure.

[0023] S2. Set the trigger probe 2 to the first position, and set the first starting angle α1 and the first feed speed v1 of the trigger probe 2, wherein, as Figure 3As shown, the first starting angle α1 refers to the angle formed by the line connecting the center 21 of the trigger probe 2 and the center 11 of the standard ball and the C-axis of the machine tool; the first feed speed v1 refers to the linear velocity of the trigger probe 2 moving toward the surface of the standard ball 1. In this embodiment, the values ​​of the first starting angle α1 and the first feed speed v1 can be determined according to the probe sensitivity and the system sampling frequency. For example, the value of the first starting angle α1 is 80-90° to ensure that the center of the trigger probe 2 is approximately coplanar with the equatorial plane of the standard ball 1, and the value of the first feed speed v1 is 0.1-0.3 mm / s to ensure triggering stability and avoid secondary collisions and overshoot.

[0024] The XYZ axes of the three-dimensional five-axis machine tool 100 are locked, and the C axis of the three-dimensional five-axis machine tool 100 is driven to rotate equally to drive the standard ball 1 to rotate. During the rotation of the standard ball 1, the trigger probe 2 is controlled to move toward the standard ball 1 with the same first starting angle α1 and first feed speed v1 each time, so that the trigger probe 2 and the N sampling points on the surface of the standard ball 1 make point contact in sequence, and ensure trigger consistency.

[0025] Furthermore, when the trigger probe 2 comes into contact with the i-th sampling point on the surface of the standard sphere, the spatial coordinates (x, y) of the center of the sphere in the machine tool coordinate system at that moment are recorded. i ,y i ,z i )(i=1, 2, 3,..., N);

[0026] Specifically, the trigger probe 2 is first controlled to move toward the standard ball 1 according to the set first starting angle α1 and first feed speed v1 until the trigger probe 2 contacts the first sampling point p0 on the surface of the standard ball 1, and the spatial coordinate value of the center of the ball of the trigger probe 2 in the machine tool coordinate system is recorded at this moment.

[0027] Control the trigger probe 2 to move away from the surface of the standard ball 1, so that it no longer contacts the surface of the standard ball 1;

[0028] The C-axis of the three-dimensional five-axis machine tool 100 is rotated in equal parts to drive the standard ball 1 to rotate by a preset angle;

[0029] The trigger probe 2 is controlled to move toward the standard ball 1 at the same first starting angle α1 and first feed speed v1 until the trigger probe 2 contacts the next sampling point p1 on the surface of the standard ball 1, and the spatial coordinate value of the center of the trigger probe 2 in the machine tool coordinate system at that moment is recorded.

[0030] Repeat the above steps until the trigger probe 2 makes point contact with N sampling points on the surface of the standard sphere 1 in sequence, and record the spatial coordinates (x, y, x) of the center of the sphere in the machine tool coordinate system at each point contact. i ,y i ,z i )(i=1, 2, 3,..., N);

[0031] S3. Place the trigger probe 2 in the second position, and set the second starting angle α2 and the second feed speed v2 of the trigger probe 2. The first position and the second position are different. The definitions of the second starting angle α2 and the second feed speed v2 are the same as those of the first starting angle α1 and the first feed speed v1. The values ​​of the second starting angle α2 and the second feed speed v2 are the same as those of the first starting angle α1 and the first feed speed v1.

[0032] Lock the Z and C axes of the 3D five-axis machine tool 100, and drive the X and Y axes of the 3D five-axis machine tool 100 to perform interpolation motion, so as to drive the trigger probe 2 to move from the second position along a preset circular trajectory around the standard sphere 1. Each time the trigger probe 2 is located at a predetermined point on the preset circular trajectory, the 3D five-axis machine tool 100 drives the trigger probe 2 to move towards the standard sphere 1 at the same second starting angle α2 and second feed speed v2, so that the trigger probe 2 makes point contact with M sampling points on the surface of the standard sphere 1 in sequence. When the trigger probe 2 makes contact with the surface of the standard sphere at the j-th sampling point, record the spatial coordinate value (x, y, y) of the center of the trigger probe 2 in the machine tool coordinate system at that moment. j ,y j ,z j (j=1, 2, 3, ..., M); throughout the entire process of the trigger probe 2 moving along a circular trajectory around the standard sphere 1 and the trigger probe 2 making point contact with the M sampling points on the surface of the standard sphere 1 in sequence, the standard sphere 1 does not rotate;

[0033] Specifically, firstly, a preset circular trajectory is generated around the standard sphere 1;

[0034] When the trigger probe 2 is located at the starting point (such as the second position) of the preset circular trajectory, the three-dimensional five-axis machine tool 100 drives the trigger probe 2 to move towards the standard ball 1 according to the set second starting angle α2 and second feed speed v2 until the trigger probe 2 contacts the first sampling point p2 on the surface of the standard ball 1, and records the spatial coordinate value of the center of the ball of the trigger probe 2 in the machine tool coordinate system at that moment;

[0035] The trigger probe 2 is moved away from the surface of the standard ball 1 by the three-dimensional five-axis machine tool 100, so that it is no longer in contact with the surface of the standard ball 1;

[0036] The X-axis and Y-axis of the three-dimensional five-axis machine tool 100 are driven to perform interpolation motion, so as to drive the trigger probe 2 to move along a preset circular trajectory around the standard ball 1 until it reaches the next predetermined point on the preset circular trajectory.

[0037] The trigger probe 2 is driven by the three-dimensional five-axis machine tool 100 to move toward the standard ball 1 at the same second starting angle α2 and second feed speed v2 until the trigger probe 2 contacts the next sampling point p3 on the surface of the standard ball 1, and the spatial coordinate value of the center of the ball of the trigger probe 2 in the machine tool coordinate system is recorded at this moment.

[0038] Repeat the above steps until the trigger probe 2 moves along the preset circular trajectory, and during the movement, it sequentially makes point contact with M sampling points on the surface of the standard sphere 1, and records the spatial coordinates (x, y, x) of the center of the sphere in the machine tool coordinate system at each point contact. j ,y j ,z j )(j=1, 2, 3,...,M);

[0039] Therefore, this embodiment can obtain different sampling point data (i.e., the spatial coordinate value of the center of the ball of the trigger probe 2 in the machine tool coordinate system) at another different location, so as to form a more uniformly distributed set of sampling points on both sides, thereby ensuring the accuracy of the calibration results;

[0040] In this embodiment, N and M are both positive integers greater than or equal to 50. For example, in this embodiment, N=M=51. The movement of the trigger probe 2 can be achieved by manual control, automatic control, etc., as long as the trigger probe 2 can contact the spherical surface of the standard ball 1.

[0041] S4. Merge all the spatial coordinate values ​​of the center of the trigger probe 2 in the machine tool coordinate system recorded in steps S2 and S3 into a dataset, and perform data cleaning on the dataset. The data cleaning includes: removing duplicate sampling points and eliminating obvious outliers (such as outliers that deviate from the average value by more than 1 mm). In this embodiment, this process can be completed using MATLAB data analysis tools.

[0042] Furthermore, on the XY plane, the spatial coordinates (x, y, y) of the center of the trigger probe 2 obtained in step S2 are... i ,y i ,z i The fitting process is performed to obtain the elliptical fitted motion trajectory of the trigger probe 2 relative to the standard sphere 1 (e.g., ...). Figure 4 As shown in the figure, the center of the elliptical fitting motion trajectory is determined as the projection position of the C-axis rotation center on the XY plane, and the normal vector nC of the XY plane is determined so as to reflect the spatial attitude of the C-axis through the normal vector nC. Since the C-axis rotates equally in step S2, the motion trajectory of the trigger probe 2 relative to the standard ball 1 should theoretically be a circle. However, due to the influence of the slight eccentricity of the C-axis rotation center of the machine tool, the tilt of the rotation surface, and the non-orthogonal error of the coordinate system, the relative motion trajectory of the trigger probe 2 is actually an ellipse. Therefore, in this embodiment, the planar position of the C-axis rotation center and the spatial attitude of the C-axis can be identified simultaneously through elliptical fitting, which serves as the geometric prior for subsequent coordinate unification and pre-stroke modeling.

[0043] And, on the XY plane, the spatial coordinates (x, y) of the center of the trigger probe 2 obtained in step S3. j ,y j ,z j The fitting process is performed to obtain the circular fitted motion trajectory of the trigger probe 2 as it moves around the standard ball 1. Figure 5 Since the standard ball 1 is fixed in step S3 and the machine tool structure error has little impact on the motion trajectory of the trigger probe 2, the spatial position of the ball center of the trigger probe 2 in step S3 is ideally circular after being projected onto the XY plane. The circular trajectory obtained by fitting is further used to supplement the data of the elliptical trajectory obtained in step S2 to improve the ball center fitting accuracy.

[0044] S5. Perform spherical fitting based on the spatial coordinate values ​​in the dataset to obtain a standard sphere model (e.g., ...). Figure 6 (as shown), and solve for the center C and radius R of the standard sphere model;

[0045] The process of solving for the center C and radius R of the standard sphere model includes the following steps:

[0046] Outliers in the dataset are removed using algorithms such as RANSAC (Random Sample Consensus) or the 3σ rule, and a weighted least squares objective function J is constructed based on the remaining spatial coordinates.

[0047]

[0048] Among them, w p These are the weighting coefficients, and σ0 is the residual scaling parameter. Let be the fitting error of the p-th spatial coordinate value in the dataset, and , (x c y c z c) represents the coordinates of the center of the fitted standard sphere model, and R represents the radius of the fitted standard sphere model;

[0049] Iterative calculations are performed based on the LM (Levenberg-Marquardt) algorithm:

[0050]

[0051]

[0052] Where λ is the damping factor, if J decreases, then λ←λ / η, if J increases, then λ←λ·η, η is the damping adjustment coefficient, and in this embodiment, η=10; W is the weight matrix; I is the identity matrix; r= Let be the residual vector of the spherical fitting, where q represents the q-th spatial coordinate value in the dataset; θ （k+1） θ （k） Let be the parameter values ​​for the (k+1)th and kth iterations, respectively, and Δθ be the parameter update amount for this iteration, which can be obtained from... We obtain T; T represents the matrix transpose;

[0053] The iterative calculation stops when the convergence condition is met, and the coordinates of the sphere's center (x, y) at this point are output. c y c z c ) and radius R, to serve as the center C of the standard sphere model (i.e. The iterative convergence condition is as follows: (The given information is incomplete and requires further context.)

[0054]

[0055] in, , These are the objective function values ​​(i.e., the weighted sum of squared residuals) for the kth and (k+1)th iterations, respectively, reflecting the current fitting error; This represents the absolute value of the largest component of the parameter update Δθ in this iteration;

[0056] Results and evaluations are based on RMS and / or Max, and include:

[0057]

[0058] Wherein, RMS (Root Mean Square) is the root mean square value of the spherical fitting residual, used to measure the overall accuracy of the spherical fitting; Max (Maximum Residual) is the absolute maximum value of the spherical fitting residual, used to measure the local range; RMS and Max can be set according to factors such as the parameters of the trigger probe 2. For example, in this embodiment, RMS ≤ 0.005 mm and Max ≤ 0.010 mm are taken. If RMS and Max do not reach the preset accuracy threshold, a resampling and refitting process will be performed.

[0059] S6. Establish a pre-travel-directionism model, and correct each spatial coordinate value in the dataset based on the pre-travel-directionism model to obtain corrected spatial coordinate values;

[0060] Specifically, the pre-stroke-directionism model is established using the following formula:

[0061]

[0062] in, The directional pre-travel compensation amount for the current spatial coordinates (x, y, z) in the dataset is used to represent the systematic deviation of the trigger probe 2 under the current incident direction. The incident direction refers to the direction of the line connecting the center of the trigger probe 2 (current spatial coordinates (x, y, z)) and the center of the standard sphere model. In this embodiment, the incident direction can be represented by the unit normal vector n of the trigger probe 2 in the machine tool coordinate system, and the unit normal vector... It can be determined by the probe attitude matrix R corresponding to the current spatial coordinates (x, y, z) in the dataset. The probe attitude matrix R is the attitude rotation matrix of the trigger probe 2 under the current spatial coordinates (x, y, z), which can be calculated in real time by the B and C axis angles of the machine tool control system. x n y n z These are the components of the unit normal vector n in the X, Y, and Z directions, respectively.

[0063] Δ0 is the average of the distance differences from the sampling point corresponding to each spatial coordinate value in the dataset to the center of the standard sphere model and the center of the trigger probe 2, respectively. For example, for sampling point 1, its distances to the center of the standard sphere model and the center of the trigger probe 2 are d1 and d1', respectively. Then, the distance difference Δd1 corresponding to sampling point 1 is Δd1 = |d1 - d1'|. Similarly, the distance difference Δd2 corresponding to sampling point 2 can be obtained as Δd2 = |d2 - d2'|, and so on, until the distance difference of the sampling point corresponding to each spatial coordinate value in the dataset is obtained. Then, the average of the distance differences of the sampling points is taken as Δ0. x k y kz α0, β0, γ0, and η0 are the first-order directional coefficients in the X, Y, and Z directions, respectively; α0, β0, γ0, and η0 are all higher-order coupling correction terms.

[0064] Furthermore, each spatial coordinate value in the dataset is corrected based on the pre-trip-directionism model to obtain corrected spatial coordinate values, including the following steps:

[0065] The corrected spatial coordinate values ​​are obtained based on the following formula:

[0066]

[0067] in, To correct spatial coordinate values;

[0068] Therefore, this embodiment can correct the directional deviation of the trigger probe 2 when it triggers sampling under different incident directions and different attitudes by using the pre-stroke-directivity model, thereby achieving quantitative compensation for the dependence of the probe's incident direction.

[0069] S7. Establish a mapping relationship from the measurement coordinates to the machine tool coordinates based on the corrected spatial coordinate values ​​to complete the calibration. The mapping relationship is as follows:

[0070]

[0071] Wherein, f(n) is a spatial compensation vector established based on the spatial coordinate values ​​of the trigger probe 2 under different incident directions, used to correct the spatial coordinate values. Mapped to the machine tool coordinate system to compensate for system errors; The corrected coordinates of the target point in the machine tool coordinate system;

[0072] Furthermore, in this embodiment there are ΔX(n), ΔY(n), and ΔZ(n) are the spatial compensation components in the X, Y, and Z directions, respectively. The spatial compensation quantity f(n) can be determined by polynomial interpolation or spline interpolation operations on the spatial coordinate values ​​corresponding to different incident directions.

[0073] In summary, the present invention first samples the ball using a trigger probe in two modes (i.e., steps S2 and S3), and then performs spherical fitting based on the spatial coordinate values ​​of the ball center obtained by the trigger probe in the two modes, so as to correct the position of the standard ball center (i.e., obtain the center C and radius R of the standard ball model), thereby improving the accuracy of subsequent spatial coordinate value correction.

[0074] Furthermore, this invention constructs a pre-stroke-directivity model based on the center of a standard sphere model. This model is used to correct each spatial coordinate value in the dataset, thereby correcting the directional deviation of the trigger probe when it triggers sampling under different incident directions and postures. Finally, a precise mapping relationship between the measurement coordinates and the machine tool coordinates can be obtained. Based on this mapping relationship, the automatic alignment and machining accuracy of the three-dimensional five-axis machine tool can be significantly improved.

[0075] It should be noted that, in this document, terms such as "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0076] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for calibrating a trigger-type probe on a three-dimensional five-axis machine tool, characterized in that, Includes the following steps: Lock the XYZ axes of the three-dimensional five-axis machine tool, drive the C axis of the three-dimensional five-axis machine tool to rotate the standard ball, and control the trigger probe to move toward the standard ball with the same first starting angle and first feed speed each time, so that the trigger probe makes point contact with N sampling points on the surface of the standard ball in sequence, and record the spatial coordinate value of the center of the ball of the trigger probe in the machine tool coordinate system at each point contact. The Z-axis and C-axis of the three-dimensional five-axis machine tool are locked, and the X-axis and Y-axis of the three-dimensional five-axis machine tool are driven to perform interpolation motion, so as to drive the trigger probe to move along a preset circular trajectory around the standard sphere. Each time the trigger probe is located at a predetermined point on the preset circular trajectory, the three-dimensional five-axis machine tool drives the trigger probe to move towards the standard sphere with the same second starting angle and second feed speed, so that the trigger probe makes point contact with M sampling points on the surface of the standard sphere in sequence, and records the spatial coordinate value of the center of the sphere of the trigger probe in the machine tool coordinate system at each point contact. The spatial coordinates of the center of all the trigger probes in the machine tool coordinate system are merged into a dataset, and a spherical fit is performed based on the spatial coordinates in the dataset to obtain a standard sphere model, and the center of the standard sphere model is calculated. A pre-travel-directionism model is established based on the center of the standard sphere model, and each spatial coordinate value in the dataset is corrected based on the pre-travel-directionism model to obtain the corrected spatial coordinate values; The mapping relationship between the measurement coordinates and the machine tool coordinates is established based on the corrected spatial coordinate values ​​in order to complete the calibration.

2. The trigger-type probe calibration method as described in claim 1, characterized in that, The trigger probe is controlled to move toward the standard ball from a first position with the same first starting angle and first feed speed each time, and the trigger probe is controlled to move along a preset circular trajectory around the standard ball from a second position.

3. The trigger-type probe calibration method as described in claim 1, characterized in that, The first starting angle and the second starting angle are both 80-90°, and the first feed rate and the second feed rate are both 0.1-0.3 mm / s.

4. The trigger-type probe calibration method as described in claim 1, characterized in that, Solving for the center C of a standard sphere model involves the following steps: Construct a weighted least squares objective function J based on spatial coordinate values: ； Among them, w p These are the weighting coefficients, and σ0 is the residual scaling parameter. Let be the fitting error of the p-th spatial coordinate value in the dataset, and , (x c y c z c ) represents the coordinates of the center of the fitted standard sphere model, and R represents the radius of the fitted standard sphere model; Iterative calculation based on the LM algorithm: ； ； Where λ is the damping factor; if J decreases, then λ←λ / η; if J increases, then λ←λ·η, where η is the damping adjustment coefficient; W is the weight matrix; I is the identity matrix; r= , where is the residual vector of the spherical fitting, q represents the q-th spatial coordinate value in the dataset; θ （k+1） θ （k） Δθ represents the parameter values ​​for the (k+1)th and kth iterations, respectively, and Δθ represents the parameter update amount for this iteration. The iterative calculation stops when the convergence condition is met, and the coordinates of the sphere's center (x, y) at this point are output. c y c z c ), with the center C of the sphere as the standard sphere model.

5. The trigger-type probe calibration method as described in claim 4, characterized in that, The iterative convergence condition is as follows: ； in, , These are the objective function values ​​for the kth and (k+1)th iterations, respectively, reflecting the current fitting error; This represents the absolute value of the largest component of the parameter update Δθ in this iteration.

6. The trigger-type probe calibration method as described in claim 1, characterized in that, The pre-stroke-direction model is established using the following formula: ； in, n is the directional pre-travel compensation amount for the current spatial coordinates (x, y, z) in the dataset; x n y n z These represent the components of the unit normal vector n of the trigger probe in the machine tool coordinate system in the X, Y, and Z directions, respectively. ; Δ0 is the average distance difference between the sampling point corresponding to each spatial coordinate value in the dataset and the center of the standard sphere model and the center of the trigger probe, respectively; k x k y k z α0, β0, γ0, and η0 are the first-order directional coefficients in the X, Y, and Z directions, respectively; α0, β0, γ0, and η0 are all higher-order coupling correction terms.

7. The trigger-type probe calibration method as described in claim 6, characterized in that, The corrected spatial coordinate values ​​are obtained based on the following formula. : .

8. The trigger-type probe calibration method as described in claim 7, characterized in that, The mapping relationship is as follows: ； Where f(n) is a spatial compensation vector established based on the spatial coordinate values ​​of the trigger probe under different incident directions, used to correct the spatial coordinate values. Mapped to the machine tool coordinate system; This refers to the corrected coordinates of the target point in the machine tool coordinate system.

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