Dynamic Compensation Method for Pitch and Perpendicularity Errors in CNC Machine Tools

Abstract

This invention discloses a dynamic compensation method for pitch and perpendicularity errors in CNC machine tools, comprising the following steps: constructing and updating the comprehensive state vector of the machine tool in real time; extracting a set of time-varying geometric error parameters with clear physical meaning from the state vector in real time, the set of time-varying geometric error parameters including a transient pitch error table based on dynamic estimation of axis position, temperature and load force, and a dynamic perpendicularity angle change based on dynamic identification of structural temperature difference and off-center load moment; calculating the multi-axis synchronous correction command position required to offset the current error; generating a multi-axis linkage micro-compensation command vector that is strictly synchronized with the original command cycle by subtracting the correction command position from the original interpolation command; injecting the micro-compensation command vector into the command end of the CNC system position loop through command feedforward superposition, or acting on the system coordinate transformation layer by writing it into a high-speed dynamic coordinate offset.

Description

Technical Field

[0001] This invention relates to the field of CNC machine tool control technology, and in particular to a dynamic compensation method for pitch error and perpendicularity error of CNC machine tools. Background Technology

[0002] Against the backdrop of rapid development in modern manufacturing and increasing demand for high-precision components, CNC machine tools, as core equipment in the field of intelligent manufacturing, directly determine the quality level and production efficiency of key industries such as high-end equipment, aerospace, and automobile manufacturing. However, in actual processing, pitch and perpendicularity errors inherent in the machine tools themselves can significantly reduce machining accuracy and surface quality. Therefore, researching and implementing dynamic compensation methods for pitch and perpendicularity errors in CNC machine tools can not only effectively solve the limitations of traditional static compensation methods in adapting to dynamic processing environment changes, but also enhance the adaptability of CNC machine tools in high-speed, high-precision, and complex surface machining scenarios, promoting the transformation and upgrading of the manufacturing industry towards intelligence, precision, and efficiency. Furthermore, it can provide key technical support for the processing of core components in high-end equipment manufacturing, precision instrument research and development, and national defense and military industries, enhancing my country's independent innovation capabilities and international competitiveness in the field of intelligent manufacturing, thereby promoting the optimization and upgrading and high-quality development of the entire manufacturing industry chain, forming a complete innovation chain from basic research to industrial application.

[0003] Traditional CNC machine tool error compensation schemes generally employ independent axis compensation or sequential compensation strategies. This involves first compensating for the positioning errors of each axis, and then attempting to compensate for angular errors such as perpendicularity through coordinate system rotation. This method has inherent drawbacks: when compensating for perpendicularity errors, correcting the command on one axis alters the actual projected position of the tool on another axis, potentially disrupting the already achieved pitch compensation and even introducing new contour errors. In multi-axis simultaneous machining of complex surfaces, this step-by-step, decoupled compensation method easily leads to incoordination between axes, generating servo tracking errors, and in severe cases, potentially causing jitter or overshoot. Therefore, a dynamic compensation method for CNC machine tool pitch and perpendicularity errors is proposed. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by proposing a dynamic compensation method for pitch and perpendicularity errors in CNC machine tools.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A method for dynamic compensation of pitch error and perpendicularity error in CNC machine tools includes the following steps: Construct and update in real time a comprehensive machine tool state vector containing temperature, load, and vibration information; The state vector is input to a dynamic geometric error parameter decoupling module. The dynamic geometric error parameter decoupling module uses prior knowledge of the machine tool structure to separate a set of time-varying geometric error parameters with clear physical meaning from the state vector in real time. The set of time-varying geometric error parameters includes a transient pitch error table based on dynamic estimation of shaft position, temperature and load force, and a dynamic perpendicularity angle change based on dynamic identification of structural temperature difference and off-center load moment. The time-varying geometric error parameter set is input into a multi-axis collaborative micro-compensation command generator. The generator performs real-time inverse kinematics solution based on the machine tool kinematics model containing real-time geometric error parameters to calculate the command position after multi-axis synchronous correction required to offset the current error. By subtracting the corrected command position from the original interpolation command, a multi-axis linkage micro-compensation command vector that is strictly synchronized with the original command cycle is generated. The micro-compensation command vector is injected into the command end of the CNC system position loop through the command feedforward superposition method, or it is applied to the system coordinate transformation layer through the high-speed dynamic coordinate offset method, so as to complete the unified and coordinated compensation of dynamic pitch error and dynamic perpendicularity error. During machining breaks, rapid and specialized in-situ measurements are performed using machine tool probes or micro-displacement sensors to obtain positioning and angular residuals within the machining space. The positioning residual is mainly associated and fed back to the dynamic pitch error identification module and its corresponding physical driving sub-model for parameter updates. At the same time, the angle residual is mainly associated and fed back to the dynamic perpendicularity identification module and its corresponding physical driving sub-model for parameter updates, thereby achieving accurate traceability of error sources and independent optimization of the model.

[0006] The method is specifically applied to vertical machining centers, gantry machine tools, or five-axis linkage CNC machine tools to compensate for time-varying dynamic pitch errors and dynamic perpendicularity errors caused by thermal deformation, force deformation, and wear, thereby improving their spatial positioning accuracy during long-term, variable-condition machining.

[0007] The above further includes: Furthermore, the execution process of the dynamic geometric error parameter decoupling module specifically includes: By combining the temperature of the spindle or lead screw with the axial load force through an embedded simplified physical model, the pitch error increment at different positions of each axis is estimated in real time to dynamically update the transient pitch error table. By combining the temperature difference between the two columns, the off-center load moment of the workbench, and the vibration spectrum, the change in perpendicularity angle in the XY, XZ, and YZ planes is estimated in real time through differential deformation analysis, and a set of geometric parameters that change over time is output.

[0008] Furthermore, the simplified physical model is a lightweight physical driving sub-model constructed based on physical laws or empirical formulas, including a model for describing the relationship between the temperature field of the lead screw and thermal elongation, a model for describing the relationship between the temperature of the guide rollers and the change of preload, and a model for describing the relationship between the non-uniform temperature field of the column and bending deformation. The parameters of the physical driving sub-model are calibrated and iteratively updated using historical operating data and specific testing data.

[0009] Furthermore, the dynamic geometric error parameter decoupling module adopts a hybrid model architecture, which is composed of the physical driving sub-model and a data-driven correction term. The data-driven correction term employs a neural network or Gaussian process, taking the state vector and the initial output of the physical driving sub-model as input, to learn and compensate for complex coupling effects and nonlinear residual errors that the physical model fails to cover, and jointly predict the change in geometric error parameters.

[0010] Furthermore, the workflow of the multi-axis collaborative micro-compensation command generator is as follows: Receive raw path commands from the CNC system interpolator and real-time time-varying geometric error parameter sets from the upper-level decoupling module; Based on the machine tool kinematic error model that integrates the current pitch error and perpendicularity error parameters, real-time calculations are performed to determine the corrected command positions that each servo axis should theoretically execute to achieve the ideal tool pose. The difference between the corrected instruction position and the original instruction position is calculated, and a micro-compensation instruction vector is generated that acts synchronously on multiple coordinate axes.

[0011] Furthermore, the instruction feedforward superposition method is expressed as follows: in each interpolation cycle, the original interpolation instruction plus the micro-compensation instruction vector is used as a new, compensated comprehensive position instruction, which is then sent to the subsequent position loop regulator (such as a PID controller) and servo driver.

[0012] Furthermore, the high-speed dynamic coordinate offset method is expressed as follows: the micro-compensation command vector is written in real time into a dynamic offset coordinate system that is dedicated to compensation and synchronized with the machine tool coordinate system. When solving the final axis position, the transformation of the dynamic offset coordinate system is automatically superimposed on the original program coordinates.

[0013] A dynamic compensation system for pitch and perpendicularity errors in CNC machine tools includes: Sensor fusion unit: Collects temperature, load, vibration and position signals to construct a comprehensive state vector of the machine tool; Parameter decoupling unit: It has a built-in dynamic geometric error parameter decoupling module and hybrid model, which receives the state vector and outputs a time-varying set of geometric error parameters; Command generation unit: Built-in multi-axis collaborative micro-compensation command generator, which calculates and generates micro-compensation command vectors based on the geometric error parameter set and the original interpolation command; Compensation execution unit: integrated into the CNC system kernel or as a high-speed external module, injects the micro-compensation command vector into the servo control loop in real time; Feedback Update Unit: Controls the in-situ measurement of the special project and feeds back the residual data to the corresponding sub-model in the parameter decoupling unit for parameter update.

[0014] A CNC machine tool is equipped with the aforementioned dynamic compensation system, which performs real-time measurement, modeling, and collaborative compensation of dynamic pitch error and dynamic perpendicularity error caused by heat, force, and wear factors during the machining process, so as to maintain high-precision machining capability.

[0015] The present invention has the following beneficial effects: In this invention, a multi-axis collaborative micro-compensation command generator is used to perform inverse kinematics model based on a complete kinematic model containing real-time error parameters, and generate synchronous multi-axis linkage compensation commands in one go. This fundamentally avoids the problems of incoordination between axes, contour errors, and even servo conflicts that may be caused by traditional split-axis and step-by-step compensation, and ensures the smooth and synchronous integration of compensation actions with the original machining path. Attached Figure Description

[0016] Figure 1 This is a flowchart illustrating the steps of the dynamic compensation method for pitch and perpendicularity errors in CNC machine tools proposed in this invention. Detailed Implementation

[0017] 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.

[0018] Please see Figure 1 As shown, this invention is a dynamic compensation method for pitch error and perpendicularity error of CNC machine tools, comprising the following steps: Construct and update in real time a comprehensive machine tool state vector containing temperature, load, and vibration information; The state vector is input to a dynamic geometric error parameter decoupling module. The dynamic geometric error parameter decoupling module uses prior knowledge of the machine tool structure to separate a set of time-varying geometric error parameters with clear physical meaning from the state vector in real time. The set of time-varying geometric error parameters includes a transient pitch error table based on dynamic estimation of shaft position, temperature and load force, and a dynamic perpendicularity angle change based on dynamic identification of structural temperature difference and off-center load moment. The time-varying geometric error parameter set is input into a multi-axis collaborative micro-compensation command generator. The generator performs real-time inverse kinematics solution based on the machine tool kinematics model containing real-time geometric error parameters to calculate the command position after multi-axis synchronous correction required to offset the current error. By subtracting the corrected command position from the original interpolation command, a multi-axis linkage micro-compensation command vector that is strictly synchronized with the original command cycle is generated. The micro-compensation command vector is injected into the command end of the CNC system position loop through the command feedforward superposition method, or it is applied to the system coordinate transformation layer through the high-speed dynamic coordinate offset method, so as to complete the unified and coordinated compensation of dynamic pitch error and dynamic perpendicularity error. During machining breaks, rapid and specialized in-situ measurements are performed using machine tool probes or micro-displacement sensors to obtain positioning and angular residuals within the machining space. The positioning residual is mainly associated and fed back to the dynamic pitch error identification module and its corresponding physical driving sub-model for parameter updates. At the same time, the angle residual is mainly associated and fed back to the dynamic perpendicularity identification module and its corresponding physical driving sub-model for parameter updates, thereby achieving accurate traceability of error sources and independent optimization of the model.

[0019] The method is specifically applied to vertical machining centers, gantry machine tools, or five-axis linkage CNC machine tools to compensate for time-varying dynamic pitch errors and dynamic perpendicularity errors caused by thermal deformation, force deformation, and wear, thereby improving their spatial positioning accuracy during long-term, variable-condition machining.

[0020] In one embodiment, the execution process of the dynamic geometric error parameter decoupling module specifically includes: By combining the temperature of the spindle or lead screw with the axial load force through an embedded simplified physical model, the pitch error increment at different positions of each axis is estimated in real time to dynamically update the transient pitch error table. By combining the temperature difference between the two columns, the off-center load moment of the workbench, and the vibration spectrum, the change in perpendicularity angle in the XY, XZ, and YZ planes is estimated in real time through differential deformation analysis, and a set of geometric parameters that change over time is output.

[0021] It should be noted that the specific analysis process of the dynamic geometric error parameter decoupling module is as follows: Real-time acquisition of various sensor signals from key parts of the machine tool, including: temperature distribution data obtained by temperature sensors located at key points of the lead screw nut seat, bearing seat, and bed; axial load force of each axis estimated or measured by servo motor current loop information or directly installed force sensors; vibration spectrum captured by vibration sensors installed on the spindle box, worktable, and column; and real-time position feedback from grating rulers or encoders. After timestamp alignment, filtering and noise reduction, and coordinate system unification, these multi-source heterogeneous data are fused into a structured comprehensive state vector that updates over time. Based on the obtained state vectors, estimations for two types of physics-driven processes are performed in parallel: Dynamic pitch error estimation: For each linear motion axis (such as X, Y, Z axes), a preset simplified physical model is invoked. This model includes at least one axial thermal elongation model and one axial elastic deformation model. The system inputs the current temperature field data of the lead screw (or spindle) of that axis, the axial load force at the current position point, and the time variable into the model, and calculates in real time the pitch error increment ΔP caused by thermal deformation and force deformation relative to the standard room temperature no-load condition. This increment is accumulated to the basic pitch error of that axis, thereby dynamically updating a transient pitch error table covering the measurement points of each axis. Dynamic perpendicularity estimation: For the geometric perpendicularity of the machine tool, a pre-set differential deformation analysis model is invoked. This model takes as input the temperature difference of the machine tool structure (e.g., the temperature difference between the left and right columns), the eccentric load moment borne by the worktable, and the vibration spectrum characteristics reflecting the dynamic rigidity of the structure. By calculating the structural torsion caused by asymmetric thermal deformation and asymmetric load, the change in perpendicularity angle Δθ between the XY, XZ, and YZ planes is estimated in real time. This change reflects the time-varying drift of the machine tool's reference geometric accuracy. The integrated state vector and the initially calculated geometric error parameters (ΔP, Δθ) are used as inputs and fed into a trained data-driven correction term (such as a lightweight neural network or Gaussian process model). This correction term specifically learns the complex multi-physics coupling effects, nonlinear relationships, and historical wear accumulation effects that are ignored or difficult to describe accurately by the simplified physical model, and outputs a correction value. This correction value is superimposed with the initial estimate output by the physical model to obtain the dynamic pitch error and dynamic perpendicularity parameters. The error parameters calculated using the physical model and corrected using the data-driven model are integrated and formatted to generate a structured set of geometric error parameters that varies over time. This parameter set serves as the final output of this module, and its typical characteristics are as follows: The output is no longer a general positioning error, but a dynamic parameter with direct physical interpretation, decomposed into each error source (specific axis, specific plane), providing a precise and interpretable compensation basis for subsequent cooperative instruction generation.

[0022] In one embodiment, the simplified physical model is a lightweight physical driving sub-model constructed based on physical laws or empirical formulas, including a model for describing the relationship between the temperature field of the lead screw and thermal elongation, a model for describing the relationship between the temperature of the guide rollers and the change of preload, and a model for describing the relationship between the non-uniform temperature field of the column and bending deformation. The parameters of the physical driving sub-model are calibrated and iteratively updated using historical operating data and specific testing data.

[0023] It should be noted that the specific analysis process for parameter calibration and iterative update of the physics-driven sub-model is as follows: Multiple rounds of thermal cycle operation tests were performed under machine tool no-load and various typical load combinations. Specific detection data and the machine tool's comprehensive state vector, which are relied upon by each physical drive sub-model, were collected simultaneously. Initial parameter values ​​for each sub-model were determined through data fitting. More specifically, the multiple rounds of thermal cycle operation tests included: controlling each axis of the machine tool to reciprocate at different speeds within a predetermined stroke to excite the thermal state upon which the lead screw temperature field and thermal elongation relationship model depend; applying a stepped axial load to excite the guide rail roller temperature and preload change relationship model; and simulating the non-uniform temperature field and bending deformation relationship model of the column through asymmetric loading or unilateral heat source simulation. The physical driving sub-model that has completed initial calibration is integrated into the dynamic error compensation system and run online. The system collects state vectors in real time and calls the sub-model to predict error parameters, thereby generating and executing compensation instructions. During processing breaks, a feedback update loop is triggered. The machine tool probe performs rapid specialized testing to obtain spatial positioning and angular residuals. Based on the residual type, these residuals are assigned to the corresponding physical driving sub-models, and the residual data is used to iteratively update the parameters of specific sub-models.

[0024] In one embodiment, the dynamic geometric error parameter decoupling module adopts a hybrid model architecture, which is composed of the physical driving sub-model and a data-driven correction term. The data-driven correction term employs a neural network or Gaussian process, taking the state vector and the initial output of the physical driving sub-model as input, to learn and compensate for complex coupling effects and nonlinear residual errors that the physical model fails to cover, and jointly predict the change in geometric error parameters.

[0025] In one embodiment, the workflow of the multi-axis collaborative micro-compensation command generator is as follows: Receive raw path commands from the CNC system interpolator and real-time time-varying geometric error parameter sets from the upper-level decoupling module; Based on the machine tool kinematic error model that integrates the current pitch error and perpendicularity error parameters, real-time calculations are performed to determine the corrected command positions that each servo axis should theoretically execute to achieve the ideal tool pose. The difference between the corrected instruction position and the original instruction position is calculated, and a micro-compensation instruction vector is generated that acts synchronously on multiple coordinate axes.

[0026] It should be noted that the specific analysis process of the multi-axis collaborative micro-compensation command generator is as follows: Commands and error parameters are received synchronously. The generator receives raw interpolation commands from the CNC system's interpolation cycle in real time. This instruction defines the ideal pose of the tool center point (TCP) in the machine coordinate system for the next cycle. It synchronously receives the time-varying geometric error parameter set from the dynamic geometric error parameter decoupling module. The parameter set at the current time t specifically includes: Transient pitch error table: Error increment of each axis at different positions x, for example, for the X-axis: ; Dynamic perpendicularity error: angular deviation between moving planes, for example, perpendicularity error between the XY planes. ; Constructing a kinematic model with real-time errors: Based on the machine tool topology, establish its nominal ideal forward kinematics model. Then, the real-time error parameters Injected as a variable into the model, a comprehensive kinematic error model incorporating real-time error is constructed; For example, for a three-axis vertical machining center, considering the X-axis pitch error... Y-axis pitch error Z-axis pitch error and XY plane perpendicularity error Simplified model, actual tool position With instruction position The relationship can be modeled as follows: ; in, This model defines the errors, representing other higher-order small errors that were not modeled. How does this lead to the command pose? Deviation from actual pose ; Real-time inverse kinematics solution and correction command calculation: The goal of compensation is to ensure that the actual position of the tool accurately matches the original command. The required position necessitates inverse kinematics calculations by the generator: solving for the current error present in the kinematic model. At that time, in order to achieve the actual pose The corrected command positions that each servo axis should theoretically receive. ; This is essentially the inverse of the error model described above. Continuing with the previous example, to cancel out the error, let... Inverse solution As a new axis command: ; This calculation is performed in real time within each interpolation cycle, ensuring... Includes offsetting All required axial corrections; Generate and inject a micro-compensation instruction vector generator to calculate the corrected instruction positions. With the original interpolation command The difference between them is used to obtain the micro-compensation command vector that needs to be superimposed within this interpolation cycle. : The vector This refers to the compensation amount for multi-axis coordination, achieved by... With the original instructions The data is then superimposed and sent to the servo driver, which drives the actual movement of each axis, ultimately enabling the tool to precisely reach the desired position. Positioning enables closed-loop feedforward compensation for dynamic pitch error and dynamic perpendicularity error.

[0027] In one embodiment, the instruction feedforward superposition method is expressed as follows: in each interpolation cycle, the original interpolation instruction plus the micro-compensation instruction vector is used as a new, compensated comprehensive position instruction, which is then sent to the subsequent position loop regulator (such as a PID controller) and servo drive.

[0028] It should be noted that the specific analysis process for instruction feedforward superposition is as follows: Synchronous Data Reception and Latching: In each fixed interpolation cycle (e.g., 1ms), within the CNC system's instruction processing channel, a dedicated instruction synthesis module synchronously receives and latches two input data streams. One stream is the original interpolation instruction (usually a sequence of target position values ​​for each axis) output by the core interpolation algorithm, corresponding to the target position of the current cycle. The other stream is a micro-compensation instruction vector, perfectly aligned with the current interpolation cycle, calculated in real-time by the multi-axis collaborative micro-compensation instruction generator based on the current machine tool status. ; Real-time instruction synthesis operation: After latching the data, the instruction synthesis module immediately performs a deterministic arithmetic operation. This operation is to perform axis-by-axis vector addition on the original interpolation instruction and the micro-compensation instruction vector. Specifically, for each linear axis of the machine tool, such as X, Y, and Z, the original instruction position value of that axis in the current interpolation cycle is added to the corresponding compensation component of the micro-compensation instruction vector. Generate a comprehensive position command: After completing the above addition operation, the output of the command synthesis module is a compensated comprehensive position command. Mathematically, this command is equivalent to the algebraic sum of the original command and the dynamic error compensation amount. Physically, it represents the corrected theoretical target position that each servo axis should be driven in this cycle to offset the geometric error identified at the current moment. Seamless command stream injection and distribution: The generated compensated integrated position command is then seamlessly injected into the standard CNC command stream, replacing the original interpolation command. It is then sent to the subsequent position loop controller (such as a PID controller). The position loop controller uses this integrated command as its current position setpoint, compares it with the actual position fed back by the motor encoder, generates speed or torque commands, and finally drives the motor through the servo driver, thereby achieving real-time feedforward compensation for dynamic pitch error and dynamic perpendicularity error.

[0029] In one embodiment, the high-speed dynamic coordinate offset method is expressed as follows: the micro-compensation command vector is written in real time into a dynamic offset coordinate system that is dedicated to compensation and synchronized with the machine tool coordinate system. When calculating the final axis position, the transformation of the dynamic offset coordinate system is automatically superimposed on the original program coordinates.

[0030] It should be noted that the specific analysis process for high-speed dynamic coordinate offset is as follows: Dynamic offset coordinate system creation: Within the CNC system, a dynamic offset coordinate system that is synchronized in real time with the machine tool's basic coordinate system is pre-created and activated. This coordinate system is configured to receive and carry real-time compensation commands. More specifically, the programmable logic axis interface or external coordinate system offset function provided by the CNC system kernel is called to instantiate a virtual compensation coordinate system in the system. The origin of this compensation coordinate system is initially aligned with the origin of the machine tool coordinate system, and all its motion axes are mapped and bound one-to-one with the actual physical servo axes of the machine tool to ensure that its offset transformation can directly act on the corresponding physical axis motion. Compensation vector writing: The micro-compensation command vector, which is calculated in real time by the multi-axis collaborative micro-compensation command generator to offset the dynamic pitch error and dynamic perpendicularity error at the current moment, is periodically written into the corresponding offset parameter register of the dynamic offset coordinate system via high-speed data communication. More specifically, the process of writing the micro-compensation command vector into the offset parameter register is achieved through the high-speed real-time data interface opened by the CNC system. This interface allows the external compensation system to directly write data packets containing the compensation amounts of each axis to a specified memory address or system variable at a frequency no less than the interpolation cycle of the CNC system, thereby achieving hard real-time synchronization between the micro-compensation command vector and the internal command stream of the CNC system. Automatic coordinate transformation superposition: When the coordinate transformation module of the CNC system calculates the final command position of each servo axis in each interpolation cycle, it automatically performs translation and rotation transformations defined by the dynamic offset coordinate system and superimposes them onto the original program coordinates generated by the machining program. More specifically, this is automatically completed by the position control firmware of the CNC system. In each control cycle, the firmware first calculates the theoretical original program coordinates based on the part machining program, and then immediately calls the coordinate transformation chain to correct them using the current offset value of the dynamic offset coordinate system, generating the final comprehensive position command sent to each axis servo driver. The whole process is completed within one interpolation cycle, ensuring that there is no delay in compensation. Multi-axis linkage synchronous compensation step: Through the automatic superposition of the above coordinate transformations, the original tool path is corrected in real time without disturbance, thereby synchronously applying the micro-compensation command vector containing multi-axis linkage relationship to all relevant motion axes of the machine tool, and completing the unified and coordinated compensation for time-varying geometric errors.

[0031] A dynamic compensation system for pitch and perpendicularity errors in CNC machine tools includes: Sensor fusion unit: Collects temperature, load, vibration and position signals to construct a comprehensive state vector of the machine tool; Parameter decoupling unit: It has a built-in dynamic geometric error parameter decoupling module and hybrid model, which receives the state vector and outputs a time-varying set of geometric error parameters; Command generation unit: Built-in multi-axis collaborative micro-compensation command generator, which calculates and generates micro-compensation command vectors based on the geometric error parameter set and the original interpolation command; Compensation execution unit: integrated into the CNC system kernel or as a high-speed external module, injects the micro-compensation command vector into the servo control loop in real time; Feedback Update Unit: Controls the in-situ measurement of the special project and feeds back the residual data to the corresponding sub-model in the parameter decoupling unit for parameter update.

[0032] A CNC machine tool is equipped with a dynamic compensation system that performs real-time measurement, modeling, and collaborative compensation of dynamic pitch error and dynamic perpendicularity error caused by heat, force, and wear factors during the machining process to maintain high-precision machining capabilities.

[0033] 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 variations 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 dynamic compensation of pitch error and perpendicularity error in CNC machine tools, characterized in that, Includes the following steps: Construct and update in real time a comprehensive machine tool state vector containing temperature, load, and vibration information; The state vector is input to a dynamic geometric error parameter decoupling module. The dynamic geometric error parameter decoupling module uses prior knowledge of the machine tool structure to separate a set of time-varying geometric error parameters with clear physical meaning from the state vector in real time. The set of time-varying geometric error parameters includes a transient pitch error table based on dynamic estimation of shaft position, temperature and load force, and a dynamic perpendicularity angle change based on dynamic identification of structural temperature difference and off-center load moment. The time-varying geometric error parameter set is input into a multi-axis collaborative micro-compensation command generator. The generator performs real-time inverse kinematics solution based on the machine tool kinematics model containing real-time geometric error parameters to calculate the command position after multi-axis synchronous correction required to offset the current error. By subtracting the corrected command position from the original interpolation command, a multi-axis linkage micro-compensation command vector that is strictly synchronized with the original command cycle is generated. The micro-compensation command vector is then injected into the command end of the CNC system position loop through command feedforward superposition, or applied to the system coordinate transformation layer through high-speed dynamic coordinate offset, thereby completing the unified and coordinated compensation for dynamic pitch error and dynamic perpendicularity error.

2. The dynamic compensation method for pitch error and perpendicularity error of CNC machine tools according to claim 1, characterized in that, The execution process of the dynamic geometric error parameter decoupling module specifically includes: By combining the temperature of the spindle or lead screw with the axial load force through an embedded simplified physical model, the pitch error increment at different positions of each axis is estimated in real time to dynamically update the transient pitch error table. By combining the temperature difference between the two columns, the off-center load moment of the workbench, and the vibration spectrum, the change in perpendicularity angle in the XY, XZ, and YZ planes is estimated in real time through differential deformation analysis, and a set of geometric parameters that change over time is output.

3. The dynamic compensation method for pitch error and perpendicularity error of CNC machine tools according to claim 2, characterized in that, The simplified physical model is a lightweight physical driving sub-model constructed based on physical laws or empirical formulas, including a model for describing the relationship between the temperature field of the lead screw and thermal elongation, a model for describing the relationship between the temperature of the guide rollers and the change of preload, and a model for describing the relationship between the non-uniform temperature field of the column and bending deformation. The parameters of the physical driving sub-model are calibrated and iteratively updated using historical operating data and specific testing data.

4. The dynamic compensation method for pitch error and perpendicularity error of CNC machine tools according to claim 3, characterized in that, The dynamic geometric error parameter decoupling module adopts a hybrid model architecture, which is composed of the physical driving sub-model and a data-driven correction term. The data-driven correction term employs a neural network or Gaussian process, taking the state vector and the initial output of the physical driving sub-model as input, to learn and compensate for complex coupling effects and nonlinear residual errors that the physical model fails to cover, and jointly predict the change in geometric error parameters.

5. The dynamic compensation method for pitch error and perpendicularity error of CNC machine tools according to claim 1, characterized in that, The workflow of the multi-axis collaborative micro-compensation command generator is as follows: Receive raw path commands from the CNC system interpolator and real-time time-varying geometric error parameter sets from the upper-level decoupling module; Based on the machine tool kinematic error model that integrates the current pitch error and perpendicularity error parameters, real-time calculations are performed to determine the corrected command positions that each servo axis should theoretically execute to achieve the ideal tool pose. The difference between the corrected instruction position and the original instruction position is calculated, and a micro-compensation instruction vector is generated that acts synchronously on multiple coordinate axes.

6. The dynamic compensation method for pitch error and perpendicularity error of CNC machine tools according to claim 1, characterized in that, The command feedforward superposition method is expressed as follows: in each interpolation cycle, the original interpolation command plus the micro-compensation command vector is used as a comprehensive position command, which is then sent to the subsequent position loop regulator and servo driver.

7. The dynamic compensation method for pitch error and perpendicularity error of CNC machine tools according to claim 1, characterized in that, The high-speed dynamic coordinate offset method is expressed as follows: the micro-compensation command vector is written in real time into a dynamic offset coordinate system that is dedicated to compensation and synchronized with the machine tool coordinate system. When solving the final axis position, the transformation of the dynamic offset coordinate system is automatically superimposed on the original program coordinates.

8. A dynamic compensation system for pitch error and perpendicularity error of CNC machine tools, used to implement the method according to any one of claims 1 to 7, characterized in that, include: Sensor fusion unit: Collects temperature, load, vibration and position signals to construct a comprehensive state vector of the machine tool; Parameter decoupling unit: It has a built-in dynamic geometric error parameter decoupling module and hybrid model, which receives the state vector and outputs a time-varying set of geometric error parameters; Command generation unit: Built-in multi-axis collaborative micro-compensation command generator, which calculates and generates micro-compensation command vectors based on the geometric error parameter set and the original interpolation command; Compensation execution unit: integrated into the CNC system kernel or as a high-speed external module, injects the micro-compensation command vector into the servo control loop in real time; Feedback Update Unit: Controls the in-situ measurement of the special project and feeds back the residual data to the corresponding sub-model in the parameter decoupling unit for parameter update.

9. A CNC machine tool, characterized in that, Equipped with the dynamic compensation system as described in claim 8, the system performs real-time measurement, modeling, and collaborative compensation of dynamic pitch error and dynamic perpendicularity error caused by heat, force, and wear factors during the processing.

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