A method and device for real-time compensation of spatial posture and position errors of five-axis CNC machine tools

Abstract

The present invention belongs to the technical field related to spatial error compensation of five-axis CNC machine tools. It discloses a real-time compensation method and device for the spatial attitude and position errors of a five-axis CNC machine tool. The method comprises the following steps: S1, establishing a spatial error model of the CNC machine tool; S2, separating and extracting the rotation error term from the comprehensive error term, and solving the compensation instruction for the rotation error term by obtaining a pseudo-inverse matrix method to obtain a compensation instruction for the attitude error; S3, separating the singular part and the non-singular part of the compensation value of the attitude error, replacing the ordinary inverse of the singular part parameter with a damped inverse, thereby obtaining a new attitude error compensation instruction and performing compensation; S4, subtracting the linear part of the translation axis error caused by the attitude error compensation from the linear part of the comprehensive error in the initial tool coordinate system, i.e., the translation axis error compensation instruction, and performing compensation. The present invention not only greatly improves computational efficiency, but also can better compensate for the tool attitude error of the machine tool.

Description

Technical Field

[0001] The present invention belongs to the technical field related to spatial error compensation of five-axis CNC machine tools, and more specifically, relates to a method and device for real-time compensation of spatial posture and position errors of five-axis CNC machine tools. Background Art

[0002] Compared to traditional three-axis CNC machine tools, five-axis CNC machine tools, by introducing two rotary axes, can more flexibly change the position of the tool relative to the workpiece coordinate system. This offers significant advantages in the machining of complex curved parts, but it also introduces more error terms. The main method to overcome this problem is to perform error compensation during the use phase of the five-axis CNC machine tool. Machine tool error terms are obtained through direct measurement or indirect identification, and these error terms are substituted into the error model to calculate the compensation value, thereby correcting the relative position of the tool and workpiece. After years of development, the error compensation method has formed a complete theoretical system including error modeling, measurement identification, error compensation, and corresponding effect verification.

[0003] However, most of the current error compensation models are aimed at compensating for tool spatial positioning errors. However, in side milling, whirlwind milling and other processing technologies, the tool posture error has a more significant impact on processing accuracy. The commonly used homogeneous coordinate transformation method is computationally complex and inefficient when solving posture solutions. Other methods, such as the compensation method based on screw theory, although they can obtain analytical solutions to the compensation values, require multiple iterative calculations in the actual compensation process and are not suitable for integration into CNC systems. The differential motion method can quickly obtain approximate numerical solutions and is suitable for industrial application scenarios, but it is not perfect in terms of posture error compensation. Summary of the Invention

[0004] In response to the above defects or improvement needs of the prior art, the present invention provides a real-time compensation method and device for the spatial posture and position errors of a five-axis CNC machine tool, which aims to solve the problem of low computational efficiency of the existing posture compensation method.

[0005] To achieve the above object, according to one aspect of the present invention, a method for real-time compensation of spatial posture and position errors of a five-axis CNC machine tool is provided, the method comprising the following steps:

[0006] S1, establish the spatial error model of the CNC machine tool based on the differential motion relationship of each axis of the CNC machine tool and the forward kinematics model of the CNC machine tool;

[0007] S2, based on the spatial error model, first separate and extract the rotation error term from the comprehensive error term, and solve the compensation instruction for the rotation error term by solving the pseudo-inverse matrix method to obtain the compensation instruction for the attitude error;

[0008] S3, separating the singular part and the non-singular part of the attitude error compensation value, using the damped inverse to replace the ordinary inverse of the singular part parameter, and then obtaining a new attitude error compensation instruction to compensate the attitude error of the CNC machine tool;

[0009] S4, subtracting the linear part of the translation axis error caused by the posture error compensation from the linear part of the comprehensive error in the initial tool coordinate system, that is, obtaining the translation axis error compensation instruction that needs to be compensated, so as to compensate the position error of the CNC machine tool.

[0010] Furthermore, assuming that the command positions of the machine tool axes are x, y, z, a, and c, from the perspective of the tool side kinematic chain, the ideal homogeneous coordinate system transformation matrices of the Y axis relative to the machine tool coordinate system, the X axis relative to the Y axis, and the Z axis relative to the X axis coordinate system are:

[0011]

[0012] The homogeneous coordinate transformation of the A-axis relative to the machine tool coordinate system and the C-axis relative to the A-axis coordinate system is:

[0013]

[0014]

[0015] Furthermore, the ideal homogeneous transformation matrix of the tool coordinate system relative to the worktable coordinate system is:

[0016]

[0017] Based on the differential motion vector of each axis and the differential motion matrix relative to the tool coordinate system, the transfer relationship from the differential motion vector of each axis to the tool coordinate system can be obtained:

[0018]

[0019] in, Represents the differential motion matrix from the i-axis coordinate system to the tool coordinate system; ΔE i Represents the differential motion vector of the i-axis; i = X, Y, Z, A, C.

[0020] Furthermore, the comprehensive error of the tool in its own coordinate system can be expressed as the sum of the errors of each axis transferred to the tool coordinate system:

[0021]

[0022] in, Indicates the comprehensive error of the tool in its own coordinate system; Indicates the error of each axis of the machine tool transferred to the tool coordinate system; δ itRepresents the three position errors of the tool in its own coordinate system, ε it Indicates the three angular errors of the tool in its own coordinate system;

[0023] According to formula (6), the matrix representation of the tool comprehensive error in its own coordinate system is given as:

[0024]

[0025] Finally, the expression of the spatial error model is obtained as follows:

[0026]

[0027] Furthermore, the rotation error term is first separated and extracted from the comprehensive error term, and the compensation instruction of the rotation error term is solved by the method of finding the pseudo-inverse matrix to obtain the compensation values ​​of the A and C axes, and then the compensation values ​​are used to compensate for the angle error:

[0028]

[0029] Where S yz is the perpendicularity error between the Y-axis and the Z-axis, S xz is the perpendicularity error between the X-axis and the Z-axis, ε xx is the angular error of the X-axis around the X-axis, ε xy is the angular error of the Y axis around the X axis, ε xz is the angular error of the Z axis around the X axis, ε xa is the angular error of the A-axis around the X-axis, ε xc is the angular error of the C-axis around the X-axis, ε za is the angular error of the A-axis around the Z-axis, ε zc is the angular error of the C-axis around the Z-axis, ε yx is the angular error of the X-axis around the Y-axis, ε yy is the angular error of the Y axis around the Y axis, ε yz is the angular error of the Z axis around the Y axis, ε ya is the angular error of the A-axis around the Y-axis, ε yc is the angular error of the C-axis around the Y-axis.

[0030] Furthermore, take λ 2 = 0.1 as the damping coefficient.

[0031] Furthermore, the translation axis error caused by the rotary axis error compensation can be calculated based on the differential motion relationship:

[0032]

[0033] Extract The linear error part in is recorded as Then we have:

[0034]

[0035] Furthermore, the linear part of the translational axis error caused by the rotary axis error compensation is subtracted from the linear part of the comprehensive error in the initial tool coordinate system to obtain the translational axis error compensation instruction that needs to be compensated:

[0036]

[0037] The present invention also provides a real-time compensation system for the spatial posture and position errors of a five-axis CNC machine tool. The system includes a memory and a processor. The memory stores a computer program. When the processor executes the computer program, it executes the real-time compensation method for the spatial posture and position errors of a five-axis CNC machine tool as described above.

[0038] The present invention also provides a computer-readable storage medium, which stores machine-executable instructions. When the machine-executable instructions are called and executed by a processor, the machine-executable instructions prompt the processor to implement the real-time compensation method for spatial posture and position errors of a five-axis CNC machine tool as described above.

[0039] In general, compared with the prior art, the above technical solutions conceived by the present invention provide a method and device for real-time compensation of spatial posture and position errors of a five-axis CNC machine tool, which has the following beneficial effects:

[0040] 1. The present invention solves the posture error and position error compensation instructions step by step. Compared with the traditional compensation instruction solving method, it not only greatly improves the calculation efficiency, but also can better compensate for the tool posture error of the machine tool.

[0041] 2. Based on the differential motion relationship of each axis of the CNC machine tool and the forward kinematic model of the CNC machine tool, a spatial error model of the CNC machine tool is established to transfer the error terms of each axis as differential motion to the tool coordinate system.

[0042] 3. After the tool is compensated for posture error, a new position error will be generated due to the posture error compensation. Therefore, the final compensation amount includes the original position error and the new position error caused by the posture error compensation. When solving the compensation instruction, the compensation instruction should be solved step by step by first solving the posture error and then solving the linear error.

[0043] 4. Separate the singular part and the non-singular part of the compensation value of the attitude error, and use the damped inverse to replace the ordinary inverse of the singular part parameter so that the compensation value can smoothly pass through the singular area.

[0044] 5. Take λ 2= 0.1 is used as the damping coefficient for subsequent calculations because it is a suitable intermediate value that can quickly coincide with the compensation value of the nearby non-singular interval and smoothly pass through the singular interval. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 This is a flow chart of a method for real-time compensation of spatial posture and position errors of a five-axis CNC machine tool provided by the present invention;

[0046] Figure 2 This is a schematic diagram of error transmission of a five-axis machine tool involved in the present invention (taking a double-rotary table machine tool as an example);

[0047] Figure 3 It is a schematic diagram of the ideal and actual positions of the tool;

[0048] Figure 4 Schematic diagram of the influence of different damping coefficients on the singular interval, where (a), (b), (c), and (d) correspond to the damping coefficient λ respectively. 2 0.001, 0.01, 0.1 and 1;

[0049] Figure 5 This is a flow chart of the singular interval avoidance method based on the damping inverse;

[0050] Figure 6 Schematic diagram of PDGEs and PIGEs of a five-axis machine tool, where (a), (b), (c), and (d) correspond to the translational axis PDGEs, rotary axis PDGEs, translational axis perpendicularity error, and rotary axis PIGEs, respectively;

[0051] Figure 7 Schematic diagram of the working principle of the five-axis CNC machine tool spatial error compensation system according to an embodiment of the present invention;

[0052] Figure 8 Schematic diagram comparing the body diagonal errors before and after translation axis error compensation, where (a) and (b) correspond to the PPP body diagonal detection results and the NPP body diagonal detection results, respectively;

[0053] Figure 9 This is a schematic diagram comparing the RTCP accuracy before and after rotary axis error compensation, where (a) and (b) correspond to the XYC axis linkage accuracy before and after compensation and the YZA axis linkage accuracy before and after compensation, respectively. DETAILED DESCRIPTION

[0054] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for the purpose of explaining the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0055] See also Figure 1 The present invention provides a real-time compensation method for spatial posture and position errors of a five-axis CNC machine tool, the compensation method mainly comprising the following steps:

[0056] S1, a spatial error model of the CNC machine tool is established based on the differential motion relationship of each axis of the CNC machine tool and the forward kinematics model of the CNC machine tool.

[0057] In this implementation, a dual-turret machine tool CAYXZ is used as an example to establish a forward kinematic model for the machine tool. The ideal homogeneous coordinate transformation of each component of the machine tool represents its ideal motion relative to adjacent components. Assuming that the command positions of the machine tool axes are x, y, z, a, and c, from the perspective of the tool-side kinematic chain, the ideal homogeneous coordinate transformation matrices of the Y axis relative to the machine tool coordinate system, the X axis relative to the Y axis, and the Z axis relative to the X axis coordinate system are:

[0058]

[0059] For the A-axis, the origin of the error analysis coordinate system does not coincide with the machine tool origin. This is determined by the machine tool's RTCP (Rotation Tool Center Point) parameter. Therefore, the corresponding calculations must be multiplied by the axis position offset matrix. Furthermore, because the rotation direction of the machine tool's axis of interest is opposite to that determined by the positive direction of the corresponding translational axis and the right-hand rule, the rotation angle in the ideal homogeneous transformation matrix is ​​negative. Similarly, the origin of the C-axis coordinate system does not coincide with the origin of the A-axis coordinate system, requiring corresponding processing.

[0060] Therefore, the homogeneous coordinate transformation of the A-axis relative to the machine tool coordinate system and the C-axis relative to the A-axis coordinate system is:

[0061]

[0062] Assuming that the worktable coordinate system coincides with the C-axis coordinate system, the transformation matrix between them is is the unit matrix, then the ideal homogeneous transformation matrix of the tool coordinate system relative to the worktable coordinate system is:

[0063]

[0064] At this point, the forward kinematics model of the machine tool is established, so that the motion and error transmission path of the machine tool can be known, such as Figure 2 shown.

[0065] The spatial error model of a machine tool is based on the motion transfer of forward kinematics, and the differential motion matrix can be calculated based on the homogeneous coordinate matrix. Differential motion includes micro-translation and micro-rotation, which is the motion of the error analysis coordinate system in six degrees of freedom. Corresponding to the basic error terms of each axis of the machine tool, the three position errors of the coordinate system can be regarded as micro-translation, while the three angular errors can be regarded as micro-rotation. Based on the differential motion vectors of each axis and the differential motion matrix relative to the tool coordinate system, the transfer relationship of the differential motion vectors of each axis to the tool coordinate system can be derived:

[0066]

[0067] Among them, DJ[T t i ] represents the differential motion matrix from the i (i = X, Y, Z, A, C) axis coordinate system to the tool coordinate system; ΔE i Represents the differential motion vector of the i-axis (i=X, Y, Z, A, C).

[0068] The comprehensive error of the tool in its own coordinate system can be expressed as the sum of the errors of each axis transferred to the tool coordinate system:

[0069]

[0070] in, Indicates the comprehensive error of the tool in its own coordinate system; Indicates the error of each axis of the machine tool transferred to the tool coordinate system; δ it Represents the three position errors of the tool in its own coordinate system, ε it Indicates the three angular errors of the tool in its own coordinate system.

[0071] According to formula (6), the matrix representation of the tool comprehensive error in its own coordinate system can be given:

[0072]

[0073] Finally, the expression of tool position error and posture error in the worktable coordinate system can be obtained, that is, the expression of the spatial error model is:

[0074]

[0075] At this point, the spatial error model of the machine tool has been established based on the differential motion method.

[0076] S2, based on the spatial error model, first separate and extract the rotation error term from the comprehensive error term, and solve the compensation instruction for the rotation error term by solving the pseudo-inverse matrix method to obtain the compensation instruction for the posture error.

[0077] Based on the established machine tool spatial error model, it is necessary to obtain the compensation instructions for each axis based on the inverse kinematic solution, so that the compensation instructions for each axis can compensate for the comprehensive tool posture error in the tool coordinate system after the differential motion transmission, so as to achieve the purpose of correcting the tool posture. When solving the compensation instructions, the commonly used method is: linearize the comprehensive tool error and compensation value based on the Jacobian matrix, and solve the compensation instructions through the pseudo-inverse matrix method. In practice, the compensation process can be optimized in terms of mechanism, and the compensation instructions can be solved step by step by solving the posture error first and then the linear error. For example Figure 3 The diagram below shows the principle diagram of tool position and attitude error. There is a position error between the ideal and actual tool poses. When the tool is compensated for the attitude error, a new position error due to the attitude error compensation is generated. Therefore, the final compensation value includes the original position error and the new position error due to the attitude error compensation. When solving the compensation instruction, the compensation instruction should be solved step by step, first solving the attitude error and then solving the linear error. Therefore, the rotation error term is first separated and extracted from the comprehensive error term. The compensation instruction for the rotation error term is solved by calculating the pseudo-inverse matrix. This yields the compensation values ​​for the A and C axes, which can then be used to compensate for the angular error.

[0078]

[0079] Where S yz is the perpendicularity error between the Y-axis and the Z-axis, S xz is the perpendicularity error between the X-axis and the Z-axis, ε xx is the angular error of the X-axis around the X-axis, ε xy is the angular error of the Y axis around the X axis, ε xz is the angular error of the Z axis around the X axis, ε xa is the angular error of the A-axis around the X-axis, ε xc is the angular error of the C-axis around the X-axis, ε za is the angular error of the A-axis around the Z-axis, ε zc is the angular error of the C-axis around the Z-axis, ε yx is the angular error of the X-axis around the Y-axis, ε yy is the angular error of the Y axis around the Y axis, ε yz is the angular error of the Z axis around the Y axis, ε ya is the angular error of the A-axis around the Y-axis, ε yc is the angular error of the C-axis around the Y-axis.

[0080] S3, separates the singular part and the non-singular part of the compensation value of the attitude error, uses the damped inverse to replace the ordinary inverse of the singular part parameter, and then obtains a new attitude error compensation instruction to compensate for the attitude error of the CNC machine tool.

[0081] Based on step S2: posture error compensation instruction solution method, C-axis compensation value expression CE R2 There is a term 1 / sin(a), which will cause the machine tool compensation value to be uncontrollable when the A-axis command position a approaches 0°, that is, the existence of a singular point makes the kinematic inverse solution unsolvable. Use S3: the damped inverse method described above to avoid the singular interval: separate the singular part from the non-singular part, and use the damped inverse method to replace the ordinary inverse of the singular part parameter, so that the compensation value can smoothly pass through the singular area. For the singular parameter k, if λ>0, then its damped inverse is k / (k 2 +λ 2 ), where λ becomes the damping coefficient of k. When the square of the damping inverse is 0.001, 0.01, 0.1, and 1, the effects of the ordinary inverse and the damping inverse on the C-axis compensation value are simulated respectively. At this time, each axis moves synchronously from its negative limit to its positive limit. The A-axis command position is the horizontal coordinate and the C-axis compensation value is the vertical coordinate. The simulation results are shown in the figure. Figure 4 As shown in the figure, it can be seen that the common feature of the damped inverse relative to the ordinary inverse is that when the singular parameter k continuously increases from a negative value to a certain positive value, in the singular interval (near the zero position of the A axis), the ordinary inverse simulation result tends to infinity, resulting in the planned axis compensation value being discontinuous and having a large mutation, while the damped inverse is less affected by the singular interval and can pass through the singular area more smoothly. Outside the singular area, the damped inverse simulation results are exactly the same as those of the ordinary inverse, indicating that it does not affect the motion compensation accuracy outside the singular area. As for the influence of the damping coefficient itself on the compensation value: when λ 2 The smaller the value, the faster the compensation value around the singular point can coincide with the non-singular interval, but the accuracy loss in the singular interval will be greater; when λ 2 When λ is larger, the speed at which the compensation value around the singular point coincides with the non-singular interval is slower, but the overall transition at the singular point is smoother. 2 = 0.1 is used as the damping coefficient for subsequent calculations because it is a suitable intermediate value that can quickly coincide with the compensation value of the nearby non-singular interval and smoothly pass through the singular interval. Figure 5 Shown is a flow chart of the singular interval avoidance method based on the damped inverse.

[0082] S4, subtracting the linear part of the translation axis error caused by the posture error compensation from the linear part of the comprehensive error in the initial tool coordinate system, that is, obtaining the translation axis error compensation instruction that needs to be compensated, so as to compensate the position error of the CNC machine tool.

[0083] The compensation value of the position error is divided into two parts: one is the translation axis error caused by the rotary axis error compensation, and the other is the original translation axis error. The translation axis error caused by the rotary axis error compensation can be calculated based on the differential motion relationship:

[0084]

[0085] Extract The linear error part in is recorded as Then we have:

[0086]

[0087] Subtract the linear part of the translation axis error caused by the rotary axis error compensation from the linear part of the comprehensive error in the initial tool coordinate system to obtain the translation axis error compensation instruction that needs to be compensated:

[0088]

[0089] According to the existing five-axis CNC machine tool geometric error measurement and identification scheme, 18 items of 6 position-related errors, 3 items of verticality errors, and 12 items of 6 position-related errors of each translation axis of the machine tool can be measured. Figure 6 The position-related error items among the 33 geometric error items obtained through measurement and identification are integrated into an error compensation table in a format where the first column is the axis command position and the second column is the error item value corresponding to the command position. This table is compatible with the output formats of mainstream measuring instruments on the market and can be imported into the CNC system with one click.

[0090] The specific calculation steps for the spatial error compensation value are as follows: Figure 7 As shown in the figure, after the user enables the spatial error compensation function in the CNC system's channel parameter interface and sets the starting position, spacing, number of points, and initial parameters stored in the compensation table, the CNC system kernel can obtain the command position of each feed axis in the current interpolation cycle when the machine tool feed axis moves. Based on the error compensation table, it uses linear interpolation to generate the error term for each axis at the current command position, and substitutes it into the spatial error compensation calculation model for calculation. After obtaining the compensation value for each axis at a certain command position, this compensation value is stored in the interpolation output buffer, superimposed on the command position, and output to the servo system, ultimately achieving motion compensation for each axis.

[0091] The present invention also provides a real-time compensation system for the spatial posture and position errors of a five-axis CNC machine tool. The system includes a memory and a processor. The memory stores a computer program. When the processor executes the computer program, it executes the real-time compensation method for the spatial posture and position errors of a five-axis CNC machine tool as described above.

[0092] The present invention also provides a computer-readable storage medium, which stores machine-executable instructions. When the machine-executable instructions are called and executed by a processor, the machine-executable instructions prompt the processor to implement the real-time compensation method for spatial posture and position errors of a five-axis CNC machine tool as described above.

[0093] The present invention also provides a system for realizing the real-time compensation function of the spatial posture and position error of the above-mentioned five-axis CNC machine tool, such as Figure 7 Shown, including:

[0094] Channel parameter import module: used to input the spatial error compensation function enable (the switching condition of the entire error compensation function), the machine tool mechanism chain (select the error compensation formula corresponding to the machine tool structure type according to this parameter), and the verticality error between the three translation axes.

[0095] Axis parameter import module: used to input the error compensation starting point coordinates (the system will output the compensation value only after this starting point coordinate), the number of error compensation points (corresponding to the number of measurement points in the compensation table, the command position error between nodes will be interpolated according to the error value at the node), the error compensation point spacing (representing the command spacing between compensation points), error compensation modulo enable (defining whether the compensation value after exceeding the specified compensation range is calculated modulo according to the excess distance or directly outputting the compensation value of the closest endpoint), error compensation magnification (defining the output magnification of the error compensation value), error compensation table starting parameter number (defining the offset of the starting position of the spatial error compensation table in the system to facilitate system addressing), compensation value output constraint related parameters (by constraining the compensation value by amplitude, change rate, etc., to ensure that the compensation value will not have unexpected sudden changes).

[0096] Error value import module: used to import the error compensation table, that is, the position-related error table of the machine tool. The data in the table can be parsed to obtain information such as the error item name, compensation table starting point, number of compensation points, compensation spacing, etc. These error compensation parameters can be filled into the corresponding parameter interface of the CNC system with one click.

[0097] Compensation value calculation module: Based on the geometric error terms obtained through measurement and identification, as well as the set channel parameter terms and axis parameter terms, the CNC system kernel obtains the command position of each feed axis in the current interpolation cycle, generates the error terms of each axis at the current command position through linear interpolation, and substitutes them into the compensation formula of the corresponding type of machine tool for calculation, and finally calculates the compensation value of each axis at the command position.

[0098] The compensation module can be easily integrated into existing CNC systems, eliminating the need for large-scale modifications or upgrades. This significantly reduces implementation costs and avoids the additional financial and time delays associated with system upgrades. Furthermore, because the spatial error compensation interface is universal for CNC systems, the invention can be rapidly implemented in production, providing strong support for spatial error compensation in machine tools.

[0099] The compensation module uses error compensation table parameters and other inputs, calculates compensation instructions for each axis in real time within the CNC system kernel, and outputs them to the servo system. By automatically parsing error compensation parameters based on the compensation table, the software's usability and efficiency are greatly improved, while also reducing the learning curve for users. Furthermore, for machine tools of different configurations, the corresponding error compensation formula can be selected based on the input machine tool mechanism chain. This design enables the present invention to be applied to various mainstream CNC machine tool configurations on the market, significantly enhancing its competitiveness.

[0100] Figure 8-9 The experimental results of the spatial posture and position error compensation method of a five-axis CNC machine tool according to an exemplary embodiment of the present invention are shown. Figure 8 As shown in the figure, the diagonal error measurement results of the translation axis body are measured three times when the translation axis compensation function is turned on and off. Figure 9 As shown in the figure, the RTCP accuracy (characterized by the spherical center coordinate deviation data of the standard ball in the machine tool coordinate system) in the five-axis linkage process is obtained when the rotary axis compensation function is switched on and off.

[0101] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for real-time compensation of spatial posture and position errors of a five-axis CNC machine tool, characterized by: The method comprises the following steps: S1, establish the spatial error model of the CNC machine tool based on the differential motion relationship of each axis of the CNC machine tool and the forward kinematics model of the CNC machine tool; S2, based on the spatial error model, first separate and extract the rotation error term from the comprehensive error term, and solve the compensation instruction for the rotation error term by solving the pseudo-inverse matrix method to obtain the compensation instruction for the attitude error; S3, separating the singular part and the non-singular part of the attitude error compensation value, using the damped inverse to replace the ordinary inverse of the singular part parameter, and then obtaining a new attitude error compensation instruction to compensate the attitude error of the CNC machine tool; S4, subtracting the linear part of the translation axis error caused by the posture error compensation from the linear part of the comprehensive error in the initial tool coordinate system, that is, obtaining the translation axis error compensation instruction that needs to be compensated, so as to compensate the position error of the CNC machine tool.

2. The method for real-time compensation of spatial posture and position errors of a five-axis CNC machine tool according to claim 1, characterized in that: Assuming that the command positions of the machine tool axes are x, y, z, a, and c, from the perspective of the tool side kinematic chain, the ideal homogeneous coordinate system transformation matrices of the Y axis relative to the machine tool coordinate system, the X axis relative to the Y axis, and the Z axis relative to the X axis coordinate system are: The homogeneous coordinate transformation of the A-axis relative to the machine tool coordinate system and the C-axis relative to the A-axis coordinate system is:

3. The method for real-time compensation of spatial posture and position errors of a five-axis CNC machine tool according to claim 2, characterized in that: The ideal homogeneous transformation matrix of the tool coordinate system relative to the worktable coordinate system is: Based on the differential motion vector of each axis and the differential motion matrix relative to the tool coordinate system, the transfer relationship from the differential motion vector of each axis to the tool coordinate system is obtained: Among them, DJ[T t i ] represents the differential motion matrix from the i-axis coordinate system to the tool coordinate system; ΔE i Represents the differential motion vector of the i-axis; i = X, Y, Z, A, C.

4. The method for real-time compensation of spatial posture and position errors of a five-axis CNC machine tool according to claim 3, characterized in that: The comprehensive error of the tool in its own coordinate system is expressed as the sum of the errors of each axis transferred to the tool coordinate system: in, Indicates the comprehensive error of the tool in its own coordinate system; Indicates the error of each axis of the machine tool transferred to the tool coordinate system; δ it Represents the three position errors of the tool in its own coordinate system, ε it Indicates the three angular errors of the tool in its own coordinate system; According to formula (6), the matrix representation of the tool comprehensive error in its own coordinate system is given as: Finally, the expression of the spatial error model is obtained as follows:

5. The method for real-time compensation of spatial posture and position errors of a five-axis CNC machine tool according to claim 1, characterized in that: First, the rotation error term is separated and extracted from the comprehensive error term. The compensation instruction of the rotation error term is solved by the pseudo-inverse matrix method to obtain the compensation value of the A and C axes, and then the compensation value is used to compensate for the angle error: Where S yz is the perpendicularity error between the Y-axis and the Z-axis, S xz is the perpendicularity error between the X-axis and the Z-axis, ε xx is the angular error of the X-axis around the X-axis, ε xy is the angular error of the Y axis around the X axis, ε xz is the angular error of the Z axis around the X axis, ε xa is the angular error of the A-axis around the X-axis, ε xc is the angular error of the C-axis around the X-axis, ε za is the angular error of the A-axis around the Z-axis, ε zc is the angular error of the C-axis around the Z-axis, ε yx is the angular error of the X-axis around the Y-axis, ε yy is the angular error of the Y axis around the Y axis, ε yz is the angular error of the Z axis around the Y axis, ε ya is the angular error of the A-axis around the Y-axis, ε yc is the angular error of the C-axis around the Y-axis.

6. The method for real-time compensation of spatial posture and position errors of a five-axis CNC machine tool according to claim 1, characterized in that: Take λ 2 = 0.1 as the damping coefficient.

7. The method for real-time compensation of spatial posture and position errors of a five-axis CNC machine tool according to claim 3, characterized in that: The translation axis error caused by the rotary axis error compensation is calculated based on the differential motion relationship: Extract The linear error part in is recorded as Then we have:

8. The method for real-time compensation of spatial posture and position errors of a five-axis CNC machine tool according to claim 7, characterized in that: Subtract the linear part of the translation axis error caused by the rotary axis error compensation from the linear part of the comprehensive error in the initial tool coordinate system to obtain the translation axis error compensation instruction that needs to be compensated:

9. A real-time compensation system for spatial posture and position errors of a five-axis CNC machine tool, characterized by: The system includes a memory and a processor, the memory stores a computer program, and the processor executes the real-time compensation method for spatial posture and position errors of a five-axis CNC machine tool according to any one of claims 1 to 8 when executing the computer program.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores machine-executable instructions. When the machine-executable instructions are called and executed by the processor, the machine-executable instructions prompt the processor to implement the real-time compensation method for spatial posture and position errors of a five-axis CNC machine tool as described in any one of claims 1-8.

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