User process driven five-axis linkage machine tool kinematic chain optimization design method and system

Abstract

The invention discloses a user process driven five-axis linkage machine tool kinematic chain optimization design method and system, and the method comprises the steps: building three machine tool kinematic models of different rotating shaft arrangement position types according to the processing demand process information of a user, and simplifying the machine tool kinematic models; according to the to-be-machined workpiece cutter, the clamping condition and the cutter path, the rotating shaft sequence is preliminarily screened according to the accessibility condition; based on the rotating shaft motion amount corresponding to each point on the tool path in the machining process, further screening the rotating shaft sequence according to the number that the determinant of the Jacobian matrix is zero; according to the method, accurate planning and optimization are carried out from the initial scheme design stage of the kinematic chain, the linkage mode of the kinematic chain and the layout of the shafts are optimized through forward design, the precision of the kinematic chain is improved, the precision of the kinematic chain is improved, and the precision of the kinematic chain is improved. Therefore, higher machining precision and efficiency are realized.

Description

Technical Field

[0001] This invention relates to the field of forward design of five-axis machine tools, and more specifically to a user-process-driven method and system for optimizing the kinematic chain of a five-axis linkage machine tool. Background Technology

[0002] As a core technology in the equipment manufacturing industry, the development level of CNC machining equipment directly affects the modernization of the manufacturing sector. Currently, the machine tool industry is pursuing a dual-track approach of learning from and absorbing foreign technologies while simultaneously pursuing independent technological innovation, and has initially acquired the capability for independent R&D and manufacturing of low-to-mid-range CNC machine tools. However, in the field of high-end CNC machine tools, a significant gap remains compared to international leading levels. Specifically, this manifests in bottlenecks such as insufficient machining accuracy and performance stability of domestically produced high-end equipment, reliance on imports for high-end CNC systems, lagging development of key functional components, and long product iteration cycles. In-depth analysis reveals that a key factor behind these shortcomings lies in the imperfection of the CNC machine tool design technology system, particularly the weakness in the early conceptual design stage. This results in inherent defects in domestically produced equipment from the initial design stage, including limited variety, outdated performance indicators, and unreasonable structural layouts. Therefore, systematically conducting research on CNC machine tool design technology has irreplaceable strategic value for comprehensively improving the performance and market competitiveness of domestically produced equipment.

[0003] Currently, the technological ecosystem supporting the detailed back-end design of CNC machine tools has matured, with commercial software tools such as 3D digital modeling, engineering simulation, and finite element analysis being widely used, greatly improving the efficiency and accuracy of the detailed design phase. However, significant technical bottlenecks still exist in the early conceptual design phase of CNC machine tools. Decisions made at this stage have a decisive impact on key performance parameters such as the equipment's accuracy, motion characteristics, and reliability, but the existing technological system has not yet formed a standardized and scientific design process, and lacks efficient digital design tools and methodologies. Therefore, in-depth research on early conceptual design technologies is urgently needed.

[0004] Kinematic chain design for CNC machine tools, as a core component of the early conceptual design phase, essentially aims to construct the motion transmission logic between the tool and the workpiece. Classified by the number of motion axes, common machine tool types include dual-axis, three-axis, four-axis, five-axis, and even multi-axis linkage machine tools, with hundreds of possible kinematic chain combinations. Different kinematic chain architectures directly impact the range of machinable parts, machining accuracy, and overall machine performance. The goal of kinematic chain design is to select the most technically feasible, high-performance, and cost-effective design from a vast pool of kinematic chain options, based on the specific machining requirements of a part. Currently, research in this field faces a methodological challenge: a lack of scientific analytical tools, and traditional design practices over-reliance on engineers' experience and analogical reasoning, leading to significant deviations in machining accuracy, lengthy development cycles, and difficulties in cost control. Interdisciplinary research on kinematic chain design methods holds promise for fundamentally overcoming these bottlenecks, offering strategic advantages for shortening development cycles, improving performance, stimulating design innovation, and reducing production costs. Summary of the Invention

[0005] The purpose of this invention is to provide a user-process-driven five-axis linkage machine tool kinematic chain optimization design method and system to overcome the problems of large deviations in equipment machining accuracy, long R&D cycles, and difficulty in cost control caused by existing technologies.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A user-process-driven method for optimizing the kinematic chain of a five-axis CNC machine tool includes the following steps: S1. Based on the user's processing requirements and process information, establish three different machine tool kinematic models with different rotary axis arrangement positions, and simplify them to obtain simplified machine tool kinematic models with different rotary axis sequences. S2. Based on a simplified machine tool kinematics model with different rotation axis sequences, calculate the rotation axis motion at each point on the tool path during machining according to the workpiece, tool, clamping conditions and tool path, and perform preliminary screening of rotation axis sequences based on reachability conditions. S3. Based on the obtained simplified kinematic model, establish the Jacobian matrix of the machine tool from input to output. Based on the motion of the rotary axis corresponding to each point on the tool path during the machining process, further filter the rotary axes by sorting them according to the number of zero determinants of the Jacobian matrix. S4. Calculate the mean nonlinear error and stroke information during the processing based on the results of the screening in steps S2 and S3, and obtain the optimized kinematic chain based on the mean nonlinear error and stroke information.

[0007] Preferably, the user's processing requirements information includes the tool path, tool length, and workpiece clamping position of the part to be processed.

[0008] Preferably, machine tool kinematic models with three different rotary axis arrangement types are established based on user processing requirements and process information. Specifically, homogeneous transformation matrices are used to establish the coordinate transformation relationship between the tool coordinate system and the workpiece coordinate system. The three different rotary axis arrangement types are RRTTT, RTTTR, and TTTRR.

[0009] Preferably, the kinematic model of the machine tool with three different rotation axis arrangement types is simplified. Specifically, based on the fact that the movement direction of the moving axis is always orthogonal, the initial position parameters of some coordinate systems with the same coefficient matrix are allocated. In actual configuration, when two rotation axes are adjacent, the axes of the two rotation axes are often made to intersect.

[0010] Preferably, a simplified machine tool kinematics model based on different rotation axis sequences calculates the rotation axis motion quantities corresponding to each point on the tool path during machining, according to the workpiece, tool, clamping conditions, and tool path. Specifically, this includes: establishing the mapping relationship between the target tool axis vector, the tool tip position, and the motion quantities of each motion axis; and determining whether the selected rotation axis sequence is reachable based on the existence of the inverse kinematic solution.

[0011] Preferably, based on the obtained simplified kinematic model, a Jacobian matrix of the machine tool from input to output is established. Based on the rotational axis motion at each point on the toolpath during machining, the rotational axes are further sorted according to the number of points with a zero determinant in the Jacobian matrix. Specifically, this includes: Select the tool axis vector independent variable selection matrix based on the selected rotation axis type; Multiply the tool axis vector independent variable selection matrix with the tool axis vector to obtain the tool axis vector independent variables; Establish the Jacobian matrix of each motion axis control variable and the independent variables of tool tip position and tool axis vector, and obtain the formula for calculating the determinant of the Jacobian matrix; Substitute the obtained rotation axis motion into the Jacobian matrix determinant calculation formula to obtain the Jacobian matrix determinant of each point on the toolpath. Calculate the number of Jacobian matrix determinants that are zero based on whether the sign of the determinant of the Jacobian matrix changes between two adjacent points; Remove rotation axis sequences with a large number of zero determinants in the Jacobian matrix.

[0012] Preferably, the mean nonlinear error and stroke information during the processing are calculated based on the screening results, specifically including the following steps: 501. Substitute the selected rotation axis order, tool length, and workpiece clamping position into the simplified model of the three different rotation axis arrangement methods. 502. Based on the established simplified model, establish the mapping relationship between the target tool axis vector and the tool tip position and the motion quantities of each motion axis; 503. Substitute the toolpath into the established mapping relationship to obtain the inverse kinematics solution corresponding to each tool axis vector and the tool tip position, that is, the motion quantity corresponding to each motion axis; 504. Use linear interpolation to calculate the nonlinear error between two adjacent points on the toolpath, and calculate the mean of the nonlinear error of all adjacent points; 505. Based on the obtained motion quantities of each motion axis, calculate the travel range of each moving axis and calculate the travel information.

[0013] 506. Output the kinematic chain of each rotation axis sequence in the three arrangement positions, along with its mean nonlinear error and stroke information.

[0014] A five-axis linkage machine tool kinematics chain optimization system includes an input simplification module, a preliminary screening module, and an optimization module. The input simplification module establishes three different machine tool kinematic models with different rotary axis arrangement positions based on the user's machining requirements and process information, and simplifies them to obtain simplified machine tool kinematic models with different rotary axis sequences. The preliminary screening module, based on simplified machine tool kinematic models of different rotation axis sequences, calculates the rotation axis motion at each point on the toolpath during machining, according to the workpiece, tool, clamping conditions, and toolpath. It then performs preliminary screening of the rotation axis sequences based on reachability conditions. Next, based on the obtained simplified kinematic model, it establishes the Jacobian matrix of the machine tool from input to output. Further screening is then performed based on the rotation axis motion at each point on the toolpath during machining, according to the number of Jacobian matrix determinants that are zero. The optimization module calculates the mean nonlinear error and stroke information during the processing based on the screening results, and obtains the optimized kinematic chain based on the mean nonlinear error and stroke information.

[0015] Preferably, the user's processing requirements information includes the tool path, tool length, and workpiece clamping position of the part to be processed.

[0016] Preferably, machine tool kinematic models with three different rotary axis arrangement types are established based on user processing requirements and process information. Specifically, homogeneous transformation matrices are used to establish the coordinate transformation relationship between the tool coordinate system and the workpiece coordinate system. The three different rotary axis arrangement types are RRTTT, RTTTR, and TTTRR.

[0017] Compared with the prior art, the present invention has the following beneficial technical effects: This invention discloses a user-driven, process-driven method for optimizing the kinematic chain of a five-axis linkage machine tool. It establishes three different kinematic models of the machine tool based on user machining requirements and process information, simplifying them to obtain simplified kinematic models for different rotational axis sequences. Based on these simplified kinematic models, the motion of each rotational axis at each point on the toolpath during machining is calculated according to the workpiece, tool, clamping conditions, and toolpath. The rotational axis sequences are initially screened based on reachability conditions. A Jacobi matrix from input to output is established based on the obtained simplified kinematic models. Further screening of the rotational axes is performed based on the number of points on the toolpath with zero determinant in the Jacobi matrix, using the rotational axis motion at each point on the toolpath during machining. The mean nonlinear error and travel information during machining are calculated based on the screening results. The optimized kinematic chain is then obtained based on the mean nonlinear error and travel information. This invention performs precise planning and optimization from the initial kinematic chain design stage, optimizing the linkage method and axis layout through forward design to achieve higher machining accuracy and efficiency. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a user-process-driven five-axis linkage machine tool kinematic chain optimization design method in an embodiment of the present invention.

[0019] Figure 2 This is a schematic diagram of the kinematic chain coordinate system structure of the present invention. Detailed Implementation

[0020] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. 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 should fall within the scope of protection of the present invention.

[0021] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0022] like Figure 1 As shown, this invention provides a user-process-driven method for optimizing the kinematic chain of a five-axis machine tool. Using user machining requirements and processes as basic inputs, it establishes evaluation indicators for the kinematic chain of the five-axis machine tool, providing an effective method for the forward design of the kinematic chain. Specifically, it includes the following steps: S1. Based on the user's processing requirements and process information, establish three different machine tool kinematic models with different rotary axis arrangement positions, and simplify them to obtain simplified machine tool kinematic models with different rotary axis sequences. S2, based on a simplified machine tool kinematics model with different rotation axis sequences, calculates the rotation axis motion at each point on the tool path during machining according to the workpiece, tool, clamping conditions and tool path, and performs preliminary screening of rotation axis sequences based on reachability conditions; S3. Based on the obtained simplified kinematic model, establish the Jacobian matrix of the machine tool from input to output. Based on the motion of the rotary axis corresponding to each point on the tool path during the machining process, further filter the rotary axes by sorting them according to the number of zero determinants of the Jacobian matrix. S4. Calculate the mean nonlinear error and stroke information during the processing based on the results of the screening in steps S2 and S3, and obtain the optimized kinematic chain based on the mean nonlinear error and stroke information.

[0023] In a specific embodiment of this application, the user's processing requirements process information includes the tool path, tool length, and workpiece clamping position of the part to be processed.

[0024] Based on the user's machining requirements and process information, three different rotary axis arrangement types of machine tool kinematic models are established. Specifically, a homogeneous transformation matrix is ​​used to establish the coordinate transformation relationship between the tool coordinate system and the workpiece coordinate system. The three different rotary axis arrangement types are RRTTT, RTTTR, and TTTRR.

[0025] The kinematic models of machine tools with three different rotary axis arrangement types are simplified. Specifically, based on the fact that the movement direction of the moving axis is always orthogonal, the initial position parameters of some coordinate systems with the same coefficient matrix are allocated. In actual configuration, when two rotary axes are adjacent, the axes of the two rotary axes are often made to intersect.

[0026] Based on a simplified machine tool kinematics model with different rotation axis sequences, this paper calculates the rotation axis motion quantities corresponding to each point on the tool path during machining, according to the workpiece, tool, clamping conditions, and tool path. Specifically, this includes establishing the mapping relationship between the target tool axis vector, the tool tip position, and the motion quantities of each motion axis. The existence of an inverse kinematic solution determines whether the selected rotation axis sequence is reachable.

[0027] Based on the obtained simplified kinematic model, a Jacobian matrix for the machine tool from input to output is established. Based on the rotational axis motion at each point on the tool path during machining, the rotational axes are further sorted and filtered according to the number of zero determinants in the Jacobian matrix. Specifically, this includes: 401. Selecting the tool axis vector independent variable selection matrix based on the selected rotational axis type. 402. Multiply the tool axis vector independent variable selection matrix with the tool axis vector to obtain the tool axis vector independent variables; 403. Establish the Jacobian matrix of each motion axis control variable and the independent variables of tool tip position and tool axis vector, and obtain the formula for calculating the determinant of the Jacobian matrix; 404. Substitute the obtained rotation axis motion into the Jacobian matrix determinant calculation formula to obtain the Jacobian matrix determinant of each point on the toolpath; 405. Calculate the number of Jacobian matrix determinants that are zero, based on whether the sign of the determinant changes between adjacent points. 406. Eliminate rotation axis sequences with a large number of zero determinants in the Jacobian matrix.

[0028] Based on the results of screening in steps S2 and S3, the mean value of nonlinear error and stroke information during the machining process are calculated. Specifically, the following steps are included: 501. Substitute the selected rotary axis sorting, tool length and workpiece clamping position into the simplified model of the three different rotary axis arrangement methods established. 502. Based on the established simplified model, establish the mapping relationship between the target tool axis vector and the tool tip position and the motion quantities of each motion axis; 503. Substitute the toolpath into the established mapping relationship to obtain the inverse kinematics solution corresponding to each tool axis vector and the tool tip position, that is, the motion quantity corresponding to each motion axis; 504. Use linear interpolation to calculate the nonlinear error between two adjacent points on the toolpath, and calculate the mean of the nonlinear error of all adjacent points; 505. Based on the obtained motion quantities of each motion axis, calculate the travel range of each moving axis and calculate the travel information.

[0029] 506. Output the kinematic chain of each rotation axis sequence in the three arrangement positions, along with its mean nonlinear error and stroke information.

[0030] This embodiment of the method for selecting and determining the location of rotary axes of a five-axis machine tool based on user machining requirements and processes uses a test surface as a specific example. The steps include: determining the test surface point, the test surface point normal vector, the tool length 20, and the clamping conditions. As input, machine tool kinematic models for three rotary axis arrangement types (RRTTT, RTTTR, and TTTRR) are established and simplified to obtain simplified machine tool kinematic models. Based on the simplified machine tool kinematic models of different rotary axis sequences, the rotary axis motion quantities corresponding to each point on the tool path during machining are calculated according to the workpiece, tool, clamping conditions, and tool axis vector. The rotary axis sequences are initially screened based on reachability conditions. Based on the simplified kinematic models, a Jacobian matrix of the machine tool from input to output is established. The motion quantities of the kinematic axes are substituted, and the rotary axis sorting is further screened based on the number of zero determinants in the Jacobian matrix. Based on the simplified machine tool kinematic models of the three different rotary axis arrangement types of the selected rotary axis sequences, evaluation indicators during machining are calculated. The user determines the rotary axis sorting and arrangement position by comprehensively considering the various rating indicators.

[0031] Set the input data; The surface expression for testing is:

[0032] The expression for the normal vector of the test surface is:

[0033] Assume the tool length is 20 and the clamping conditions are as follows: .

[0034] Simplified kinematic models of machine tools with three types of rotary axis arrangement positions are established.

[0035] The coordinate systems in the machine tool and their initial position relationships are as follows: Figure 2 As shown, where, All are described in a local coordinate system, representing the initial position between the various coordinate systems.

[0036] The specific steps for establishing a simplified kinematic model of a machine tool are as follows: 2-1 Establishing the kinematic model of the tool coordinate system relative to the workpiece coordinate system: The homogeneous transformation matrix of the motion axes can be defined according to different motion axes. The homogeneous coordinates of the X, Y, Z, A, B, and C motion axes can be expressed as follows:

[0037]

[0038] The initial position between two adjacent coordinate systems The corresponding homogeneous transformation matrix can be expressed as:

[0039] in, , and They represent The X, Y, and Z components. Definition Indicates axis The homogeneous coordinate matrix corresponding to the motion that occurs. Therefore, the relationships between the workpiece coordinate system, machine tool coordinate system, and tool coordinate system can be expressed as follows: Transformation matrix of the tool coordinate system relative to the machine coordinate system:

[0040] Transformation matrix of workpiece coordinate system relative to machine tool coordinate system:

[0041] Transformation matrix of tool coordinate system relative to workpiece coordinate system:

[0042] Therefore, based on the above formula, the corresponding kinematic models for RRTTT, RTTTR, and TTTRR types can be obtained as follows: RRTTT type:

[0043] RTTTR type:

[0044] TTTRR type:

[0045] in, This represents the amount of motion of the transformed translation axis. These represent the rotation matrices after the motion transformations of the rotation axis closer to the workpiece and the rotation axis farther from the workpiece, respectively. The transformation rules are as follows:

[0046]

[0047] in, Indicates the movement axis The amount of exercise, This represents the rotation matrix corresponding to the rotation axis.

[0048] 2-2 Simplified kinematic model of machine tool In the kinematic models with three different rotation axis arrangements, the direction of motion of the translation axis always remains orthogonal, thus... Same coefficient Assigned to In this context, the initial values ​​of motion are used to simplify the model. Additionally, generally, when two rotational axes are adjacent, their axes intersect. Based on these conditions, the machine tool kinematic model in 2-1 can be simplified as follows: RRTTT type:

[0049] RTTTR type:

[0050] TTTRR type:

[0051] The rotation axis sequence is initially screened based on accessibility criteria; Let the output tool axis vector be... The output position is Initial position tool axis vector is The inverse kinematics of the ordering and positional arrangement of each motion axis is shown in Table 1: Table 1 Inverse kinematics of the motion quantities of the rotation axis

[0052] Substitute the corresponding tool axis vector. If there is an inverse solution for the motion of the corresponding rotation axis, it means that the selected rotation axis sorting is completely reachable for the current path and can be selected. Otherwise, it cannot be selected and should be eliminated.

[0053] Further filtering of the rotation axes is performed based on the number of Jacobian matrix determinants that are zero. Since the tool axis vector length is always 1, that is, Therefore, let the independent tool axis vector components be denoted as The tool axis vector can be filtered according to Table 2.

[0054] Table 2. Tool Axis Vector Independent Variable Selection Matrix

[0055]

[0056] in, Indicating the type of rotary axis closer to the workpiece allows for the generation of an independent tool axis vector. The Jacobian matrix expression can be obtained as follows:

[0057] in, , representing the motion control quantities of the moving axes X, Y, and Z. This indicates the amount of rotational motion of the axis closer to the worktable and further away from the worktable. Because... The determinant of the Jacobian matrix is:

[0058] The remaining block expressions are shown in Table 3: Table 3. Block Expressions of the Jacobian Matrix

[0059] in, Representing rotation matrices respectively The derivative generators of . The determinant of the Jacobian matrix can be further expressed as:

[0060] Substitute the calculated motion of the rotation axis into the determinant of the Jacobian matrix, and use the zero-point existence theorem to determine whether there is a zero between the two Jacobian matrix determinants, thus inferring the number of zeros in the Jacobian matrix determinant. Rotation axes with a large number of zeros in their Jacobian matrix determinants are then sorted and removed.

[0061] Calculate the evaluation indicators during the processing: The inverse kinematics calculation methods for the motion quantities of each rotation axis are shown in Table 1, and the inverse kinematics calculation methods for the motion quantities of each translation axis are shown in Table 4. Table 4 Inverse kinematics solution of motion quantities along the translation axis

[0062] in, This represents a point on the toolpath.

[0063] The calculation process for nonlinear error is as follows: 5-1 Calculate the motion of the motion axis of two adjacent points on the toolpath. and ; 5-2 The control quantity between two adjacent points is obtained through linear interpolation, that is ,in, ; 5-3 Calculate based on the simplified machine tool kinematics model Position of the cutting tip under motion ; 5-4 Calculate the nonlinear error between two adjacent points:

[0064] in, , .

[0065] It can calculate the mean nonlinear error during the processing. As an evaluation indicator output, its calculation formula is:

[0066] in, This indicates the number of points on the toolpath.

[0067] The calculation method for itinerary information is as follows: Based on the motion of the corresponding axes at each point on the toolpath, the range of motion of the X, Y, and Z axes can be determined. :

[0068] in, Points on the toolpath The corresponding motion quantities along the X, Y, and Z axes. This indicates the number of points on the toolpath.

[0069] Therefore, the travel information can be calculated using the following formula. :

[0070] The user comprehensively determines the rotation axis order and rotation axis placement: Based on the above process and engineering experience, the user makes the final determination of the sorting and arrangement of the rotating shafts.

[0071] This invention presents a method for determining the selection and layout of rotary axes in a five-axis machine tool based on user machining requirements and processes. It uses user machining requirements and processes as basic inputs and establishes evaluation indicators for the five-axis machine tool kinematic chain. Taking a test surface as an example, based on the present invention, rotary axes AC, BC, AB, and BA are directly eliminated according to the accessibility condition and the zero determinant of the Jacobian matrix. Furthermore, TTTCB is selected as the rotary axis for selection and layout in the five-axis machine tool based on the evaluation indicators. This invention differs from traditional reverse engineering methods; it starts from user needs and provides an effective method for the forward design of five-axis machine tool kinematic chains.

[0072] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A user-process-driven method for optimizing the kinematic chain of a five-axis linkage machine tool, characterized in that, Includes the following steps: S1. Based on the user's processing requirements and process information, establish three different machine tool kinematic models with different rotary axis arrangement positions, and simplify them to obtain simplified machine tool kinematic models with different rotary axis sequences. S2. Based on a simplified machine tool kinematics model with different rotation axis sequences, calculate the rotation axis motion at each point on the tool path during machining according to the workpiece, tool, clamping conditions and tool path, and perform preliminary screening of rotation axis sequences based on reachability conditions. S3. Based on the obtained simplified kinematic model, establish the Jacobian matrix of the machine tool from input to output. Based on the motion of the rotary axis corresponding to each point on the tool path during the machining process, further filter the rotary axes by sorting them according to the number of zero determinants of the Jacobian matrix. S4. Calculate the mean nonlinear error and stroke information during the processing based on the results of the screening in steps S2 and S3, and obtain the optimized kinematic chain based on the mean nonlinear error and stroke information.

2. The user-process driven five-axis linkage machine tool kinematic chain optimization design method according to claim 1, characterized in that, The user's processing requirements include the tool path, tool length, and workpiece clamping position of the part to be processed.

3. The user-process driven five-axis linkage machine tool kinematic chain optimization design method according to claim 1, characterized in that, Based on the user's machining requirements and process information, three different rotary axis arrangement types of machine tool kinematic models are established. Specifically, a homogeneous transformation matrix is ​​used to establish the coordinate transformation relationship between the tool coordinate system and the workpiece coordinate system. The three different rotary axis arrangement types are RRTTT, RTTTR, and TTTRR.

4. The user-process driven five-axis linkage machine tool kinematic chain optimization design method according to claim 1, characterized in that, The kinematic models of machine tools with three different rotary axis arrangement types are simplified. Specifically, based on the fact that the movement direction of the moving axis is always orthogonal, the initial position parameters of some coordinate systems with the same coefficient matrix are allocated. In actual configuration, when two rotary axes are adjacent, the axes of the two rotary axes are often made to intersect.

5. The user-process driven five-axis linkage machine tool kinematic chain optimization design method according to claim 1, characterized in that, Based on a simplified machine tool kinematics model with different rotation axis sequences, the rotation axis motion quantities corresponding to each point on the tool path during machining are calculated according to the workpiece, tool, clamping conditions, and tool path. Specifically, this includes: establishing the mapping relationship between the target tool axis vector, the tool tip position, and the motion quantities of each motion axis; and determining whether the selected rotation axis sequence is reachable based on the existence of the inverse kinematic solution.

6. The user-process driven five-axis linkage machine tool kinematic chain optimization design method according to claim 1, characterized in that, Based on the obtained simplified kinematic model, a Jacobian matrix for the machine tool from input to output is established. Based on the rotational axis motion at each point on the toolpath during machining, the rotational axes are further sorted and filtered according to the number of points with a zero determinant in the Jacobian matrix. Specifically, this includes: Select the tool axis vector independent variable selection matrix based on the selected rotation axis type; Multiply the tool axis vector independent variable selection matrix with the tool axis vector to obtain the tool axis vector independent variables; Establish the Jacobian matrix of each motion axis control variable and the independent variables of tool tip position and tool axis vector, and obtain the formula for calculating the determinant of the Jacobian matrix; Substitute the obtained rotation axis motion into the Jacobian matrix determinant calculation formula to obtain the Jacobian matrix determinant of each point on the toolpath. Calculate the number of Jacobian matrix determinants that are zero based on whether the sign of the determinant of the Jacobian matrix changes between two adjacent points; Remove rotation axis sequences with a large number of zero determinants in the Jacobian matrix.

7. The user-process driven five-axis linkage machine tool kinematic chain optimization design method according to claim 1, characterized in that, Based on the screening results, the mean nonlinear error and stroke information during the processing are calculated, specifically including the following steps:

501. Substitute the selected rotation axis order, tool length, and workpiece clamping position into the simplified model of the three different rotation axis arrangement methods.

502. Based on the established simplified model, establish the mapping relationship between the target tool axis vector and the tool tip position and the motion quantities of each motion axis; 503. Substitute the toolpath into the established mapping relationship to obtain the inverse kinematics solution corresponding to each tool axis vector and the tool tip position, that is, the motion quantity corresponding to each motion axis; 504. Use linear interpolation to calculate the nonlinear error between two adjacent points on the toolpath, and calculate the mean of the nonlinear error of all adjacent points; 505. Based on the obtained motion quantities of each motion axis, calculate the travel range of each moving axis and calculate the travel information; 506. Output the kinematic chain of each rotation axis sequence in the three arrangement positions, along with its mean nonlinear error and stroke information.

8. A five-axis linkage machine tool kinematic chain optimization system, characterized in that, Includes an input simplification module, a preliminary filtering module, and an optimization module: The input simplification module establishes three different machine tool kinematic models with different rotary axis arrangement positions based on the user's machining requirements and process information, and simplifies them to obtain simplified machine tool kinematic models with different rotary axis sequences. The preliminary screening module, based on simplified machine tool kinematic models of different rotation axis sequences, calculates the rotation axis motion at each point on the toolpath during machining, according to the workpiece, tool, clamping conditions, and toolpath. It then performs preliminary screening of the rotation axis sequences based on reachability conditions. Next, based on the obtained simplified kinematic model, it establishes the Jacobian matrix of the machine tool from input to output. Further screening is then performed based on the rotation axis motion at each point on the toolpath during machining, according to the number of Jacobian matrix determinants that are zero. The optimization module calculates the mean nonlinear error and stroke information during the processing based on the screening results, and obtains the optimized kinematic chain based on the mean nonlinear error and stroke information.

9. The five-axis linkage machine tool kinematic chain optimization system according to claim 8, characterized in that, The user's processing requirements include the tool path, tool length, and workpiece clamping position of the part to be processed.

10. The five-axis linkage machine tool kinematic chain optimization system according to claim 8, characterized in that, Based on the user's machining requirements and process information, three different rotary axis arrangement types of machine tool kinematic models are established. Specifically, a homogeneous transformation matrix is ​​used to establish the coordinate transformation relationship between the tool coordinate system and the workpiece coordinate system. The three different rotary axis arrangement types are RRTTT, RTTTR, and TTTRR.

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