Cutting deviation self-adaptive compensation method for edge end digital twinning drive

Abstract

The invention relates to the technical field of precision machining, in particular to an edge end digital twin drive cutting deviation self-adaptive compensation method which is executed based on a machining subprogram and a measuring subprogram which are pre-stored in a numerical control system. The method comprises the following steps: firstly, establishing communication between an edge computing controller and a numerical control system based on a predefined data interaction protocol with a fixed mapping relation; then executing the measurement subprogram to obtain the measurement point coordinates of the actual machining features of the workpiece, and obtaining the actual parameters of the workpiece features through the measurement point coordinates; then, actual parameters and theoretical parameters are read to calculate form and position size deviation, machining coordinate system correction and / or tool compensation are / is generated, and finally, a machining subprogram is executed to achieve self-adaptive compensation of machining deviation. By constructing closed-loop control of measurement-calculation-compensation, online, automatic and accurate correction of the machining deviation is achieved, and the machining precision and efficiency are remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of precision machining, and particularly relates to a cutting deviation self-adaptive compensation method driven by edge-end digital twinning. BACKGROUND

[0002] In the numerical control machining process, the identification and correction of machining deviation is a key technical difficulty affecting the overall machining precision and machining efficiency of the workpiece. The traditional deviation compensation method usually relies on an off-line detection by a three-coordinate measuring machine, and a compensation machining program is generated again according to the detection result. However, this method needs to repeatedly clamp the workpiece, which not only increases the non-machining time, but also introduces errors due to repeated positioning, directly affecting the final machining precision and consistency of the workpiece, and restricting the development and application of intelligent manufacturing technology.

[0003] The emergence of in-machine measurement technology provides a new way to solve the above problems. This technology can directly measure the workpiece on the machining machine tool without disassembly and secondary clamping, thereby effectively avoiding the positioning error caused by repeated clamping. For example, Chinese patent CN120205914A proposes an intelligent manufacturing method for precise positioning of complex curved gears based on in-machine measurement, which includes steps of measurement path planning, measurement coordinate system establishment, gear precise positioning and machining program optimization. For another example, Chinese patent CN119960379A discloses a curve random shape compensation machining method and storage medium based on in-machine measurement. The method calculates an error vector based on the error value between the theoretical measurement point and the actual measurement point, and then generates a compensation tool path for the curve to be compensated. However, the existing technical solutions focus more on the basic theoretical level of measurement path planning, measurement point arrangement strategy or optimization algorithm, and still need a lot of manual intervention in the actual application process, which makes it difficult to realize automatic closed-loop control, thereby significantly affecting the execution efficiency and precision of deviation solving and compensation.

[0004] Furthermore, based on the workpiece feature point cloud data acquired through on-machine measurement, strong computing power is required to accurately solve the workpiece's dimensional deviations. However, traditional CNC systems, limited by their built-in computing power, often struggle to meet the demands for real-time and efficient data processing. Simultaneously, how to efficiently and reliably feed the calculated compensation values ​​back to the CNC system and drive the actuator to achieve adaptive compensation machining remains a current technical challenge for the industry. For example, Chinese patent CN115647438A proposes a method for adaptive compensation machining of an ultra-large diameter-to-thickness integral box bottom. This method utilizes laser scanning technology to acquire the inner surface of the box bottom, combines it with an ultra-large laser scanning and thickness measurement device to obtain the actual wall thickness in real time, and achieves adaptive real-time compensation by adjusting the machine tool axis system. Chinese patent CN116532697A discloses a method for adaptive compensation machining of composite skin thickness, which calculates the actual thickness and corrects the machining toolpath by comparing the three-dimensional scanned point cloud. However, these solutions mostly focus on the calculation principle of compensation amount, without addressing how to seamlessly and reliably feed the calculated compensation value back to the CNC system and drive it to perform compensation machining, thus making it difficult to achieve truly integrated adaptive machining.

[0005] The rise of edge computing technology has provided a feasible technical path for expanding the computing power of CNC systems. For example, Chinese patent CN119511946A proposes an edge-end interactive computing method for on-machine measurement data based on macro variables of CNC systems. It uses the address of macro variables as the information exchange medium and designs the edge-end interactive logic for on-machine measurement results. However, this technology only stays at the data interaction level and does not build a complete technical path based on data interaction protocols to drive the automatic execution of compensation machining, nor can it form a complete adaptive compensation closed loop.

[0006] In summary, existing technologies are either limited to theoretical research on measurement and algorithms with insufficient automation, or can only solve local problems such as computing power expansion or data interaction. Therefore, there is an urgent need in this field for a method that can achieve accurate online acquisition and rapid calculation of workpiece deviations, and integrate the compensation amount into the CNC machining system through a clear and automated technical path, thereby achieving truly integrated adaptive machining. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention proposes an edge-end digital twin-driven adaptive compensation method for cutting deviations, which solves the technical problem of the inability to achieve online, automatic, and closed-loop compensation of workpiece deviations during machining, effectively improving machining accuracy and intelligence.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] In a first aspect, this invention proposes an edge-end digital twin-driven adaptive compensation method for cutting deviations, based on the execution of pre-stored machining subroutines and measurement subroutines in the CNC system, wherein the machining subroutines contain variable compensation instructions; the method includes the following steps:

[0010] S1. Based on a predefined data interaction protocol, communication is established between the edge computing controller and the CNC system. The edge computing controller is deployed at the edge of the CNC machine tool. The data interaction protocol defines the mapping relationship between workpiece shape and size measurement information and compensation information and macro variable addresses of the CNC system.

[0011] S2. Execute the measurement subroutine to obtain the coordinates of the measurement points of the actual processing features of the workpiece. Perform error compensation and feature fitting on the coordinates of the measurement points through the edge computing controller to obtain the actual parameters of the workpiece features. Store the actual parameters of the workpiece features in the corresponding macro variable address defined in the data interaction protocol.

[0012] S3. The edge computing controller reads the actual and theoretical parameters of the workpiece features from the corresponding macro variable address, calculates the form and position dimension deviation of the workpiece, generates the machining coordinate system correction amount and / or tool compensation amount, and writes the generated result into the corresponding macro variable address defined in the data interaction protocol.

[0013] S4. Execute the machining subroutine, which calls the generated machining coordinate system correction amount and / or tool compensation amount through the variable compensation instruction to achieve adaptive compensation of machining deviation.

[0014] Furthermore, the edge computing controller is equipped with an edge-to-end data interaction module, an on-machine measurement result processing module, a workpiece shape and size calculation module, and an adaptive compensation machining module; the automatic switching of each functional module is controlled by the numerical information in the address of a function selection macro variable.

[0015] Furthermore, in S2, error compensation includes probe pre-stroke error compensation and ruby ​​ball radius compensation; the specific process of error compensation and feature fitting for measurement point coordinates is as follows: call the measurement compensation value generated in advance by the probe calibration program and stored in the macro variable address, correct the measurement point coordinates, and fit the corrected measurement point coordinates to obtain the actual parameters of the workpiece features.

[0016] Further, in S2, the workpiece feature type includes at least one of point, circle, plane, cylinder, curved surface and groove; in S3, the type of form and position dimensional deviation includes at least one of distance, angle, roundness, coaxiality, concentricity, flatness, perpendicularity, parallelism and inclination.

[0017] Furthermore, the variable compensation instruction is a programmable parameter input instruction of the CNC system, used to automatically set the value in the macro variable address as the machining coordinate system offset or tool compensation value when the machining subroutine is running.

[0018] Furthermore, in the data interaction protocol, the mapping relationship between workpiece shape and size measurement information and compensation information and CNC system macro variable addresses is predefined and fixed.

[0019] Furthermore, the geometrical measurement information includes machine measurement information and geometrical dimension information; the machine measurement information includes the measurement point number, theoretical coordinates, and measured coordinates; the geometrical dimension information includes the type of machining feature, the type of geometrical dimension deviation, and the theoretical geometrical dimension; the compensation information includes the compensation target type, coordinate system correction amount, and tool compensation value.

[0020] Secondly, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-described method.

[0021] Thirdly, the present invention proposes an edge computing controller, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the steps of the above method.

[0022] Fourthly, the present invention proposes a CNC machining system, comprising: a CNC machine tool, a contact-type on-machine measurement probe, and the aforementioned edge computing controller; the edge computing controller communicates with the CNC system in the CNC machine tool via an industrial network protocol and performs data interaction using the macro variable address of the CNC system as a medium.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] (1) This invention acquires workpiece features in real time through machine measurement technology, calculates deviations and compensation amounts online with the help of edge computing controller, and finally completes the correction automatically through variable compensation instructions. This forms a fully automatic technical path of machine measurement-edge computing-macro variable feedback-variable instruction execution, and constructs a complete intelligent closed loop of perception-decision-execution. It breaks through the traditional compensation method that relies on manual and offline operation, and can correct processing deviations in real time and online, thereby significantly improving the processing efficiency of workpieces and the final processing accuracy and batch consistency.

[0025] (2) By deploying an edge computing controller, this application separates complex point cloud fitting, deviation calculation and other high computing power tasks from the CNC system, making full use of the powerful computing power of edge computing. This not only solves the technical bottleneck of traditional CNC systems that are unable to support real-time error modeling and compensation due to insufficient computing power, but also retains the advantages of CNC systems in high-precision and high-real-time motion control, realizing the complementary advantages of edge end and CNC end.

[0026] (3) The compensation method proposed in this application accurately maps measurement and compensation information to macro variable addresses through a predefined data interaction protocol and embeds variable compensation instructions in the machining subroutine. On the one hand, the calculation results of the edge calculator can be automatically written into the macro variable and directly called by the machining program, realizing true adaptive compensation without any manual intervention. On the other hand, it can flexibly adapt to different CNC systems, workpiece features and machining requirements. Users only need to adjust the NC program and protocol mapping according to the new machining object to achieve adaptive compensation without changing the underlying system architecture or carrying out complex secondary development. It has good versatility and flexibility. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the functional modules of the edge computing controller and CNC system according to an embodiment of the present invention;

[0028] Figure 2 This is an overall flowchart of the adaptive compensation method according to an embodiment of the present invention;

[0029] Figure 3 This is a schematic diagram of the in-machine measurement and error compensation process for workpiece features according to an embodiment of the present invention;

[0030] Figure 4 This is a schematic diagram illustrating the pre-stroke error generation mechanism in an embodiment of the present invention;

[0031] Figure 5 This is a schematic diagram illustrating the adaptive compensation principle of the machining coordinate system and tool compensation values ​​in an embodiment of the present invention.

[0032] Figure 6 This is a schematic diagram of the feature deviation compensation principle in an embodiment of the present invention, wherein (a) is a schematic diagram of machining coordinate system offset; (b) is a schematic diagram of tool radius compensation; and (c) is a schematic diagram of tool length compensation.

[0033] Figure 7 The diagram shows the adaptive compensation process for deviations in an embodiment of the present invention; where (a) is a diagram of the workpiece program compilation process; (b) is a diagram of the in-machine measurement process; and (c) is a diagram of the compensation machining process.

[0034] Figure 8 This is a comparison chart of the processing results of the traditional compensation method and the adaptive compensation method of the present invention in the embodiments of the present invention. Detailed Implementation

[0035] 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.

[0036] Example

[0037] refer to Figure 1 and Figure 2 This embodiment proposes an edge-end digital twin-driven adaptive compensation method for cutting deviation, which is implemented based on a pre-configured CNC machining system. The CNC machining system includes a CNC machine tool, a contact-type on-machine measurement probe, and an edge computing controller deployed at the edge of the CNC machine tool. The edge computing controller is connected to the CNC system in the CNC machine tool via an industrial Ethernet and communicates based on the TCP / IP protocol. The contact-type on-machine measurement probe is used to acquire the coordinates of the measurement point and send them to the CNC system.

[0038] To achieve edge-to-end collaborative automation, a predefined data interaction protocol is established. This protocol establishes a predefined and fixed mapping relationship between workpiece shape and dimension measurement information and compensation information and CNC system macro variable addresses. The shape and dimension measurement information includes in-machine measurement information and shape and dimension information; the in-machine measurement information includes the measurement point number, theoretical coordinates, and measured coordinates; the shape and dimension information includes the type of machining feature, the type of shape and dimension deviation, and the theoretical shape and dimension; the compensation information includes the compensation target type (coordinate system or tool), coordinate system correction amount, and tool compensation value. The workpiece feature type includes at least one of point, circle, plane, cylinder, curved surface, and groove; the type of shape and dimension deviation includes at least one of distance, angle, roundness, coaxiality, concentricity, flatness, perpendicularity, parallelism, and tilt. This embodiment takes the finishing of a workpiece with a cylindrical hole feature on a vertical machining center equipped with a Fanuc CNC system as an example. Some key mapping relationships can be defined as shown in Table 1, where A~F, H~K, M, Q~Z are system macro variables, and # address number is a user macro variable:

[0039] Table 1. Mapping relationship between information and macro variable addresses

[0040]

[0041] Function scheduling: The value in the function selection macro variable address M serves as the function switching flag. The correspondence between the value and the function is as follows: 1000: edge-to-end data interaction; 2000: in-machine measurement result processing; 3000: workpiece shape and position dimension calculation; 4000: adaptive compensation machining.

[0042] Measurement data: The theoretical coordinates of the measurement points are stored in #5001, and the measured coordinates are stored in #6001;

[0043] Geometric parameters: The theoretical center X-axis coordinate of the workpiece feature is stored in #5101, the theoretical center Y-axis coordinate is stored in #5102, the theoretical diameter is stored in #5103, the measured center X-axis coordinate is stored in #6101, the measured center Y-axis coordinate is stored in #6102, and the measured diameter is stored in #6103.

[0044] Compensation parameters: The X-axis correction value of coordinate system G54 is stored in #101; the Y-axis correction value is stored in #102; and the radius compensation value of tool No. 1 is stored in #105.

[0045] To achieve adaptive compensation, an NC program is pre-compiled and stored in the CNC system based on the workpiece's processing characteristics. This NC program includes a main program, a machining subroutine, and a measurement subroutine. The main program is responsible for process scheduling and controls the edge computing controller to switch between different functional modules by modifying the value of the function macro variable address M. The machining subroutine pre-embeds variable compensation instructions, which dynamically read the current compensation value in the macro variable address during runtime to achieve automatic adjustment of machining parameters. The measurement subroutine is used to control the probe to measure according to a preset path under the control of the CNC system and write the measurement results to the specified macro variable address.

[0046] To achieve automated processes, the edge computing controller deploys four core functional modules: an edge-to-end data interaction module, an on-machine measurement result processing module, a workpiece shape and dimension calculation module, and an adaptive compensation machining module. The edge-to-end data interaction module is responsible for reading and writing CNC system macro variables via TCP / IP protocol; the on-machine measurement result processing module is responsible for error compensation and feature fitting of the measurement point coordinates; the workpiece shape and dimension calculation module is responsible for calculating the workpiece's shape and dimension deviations; and the adaptive compensation machining module is responsible for generating machining coordinate system corrections and tool compensation amounts.

[0047] The automatic switching of each module is controlled by the numerical information within the function selection macro variable address M. When the CNC main program modifies this value, the edge computing controller detects the change and automatically activates the corresponding module without manual intervention.

[0048] See Figure 2 The prediction method provided in this embodiment is performed according to the following steps:

[0049] Step 1: The main program calls the measurement subroutine to obtain the coordinates of the measurement points of the actual machining features of the workpiece using a contact-type on-machine measurement probe. Simultaneously, the main program modifies the value of the macro variable address M in the function selection and starts the on-machine measurement result processing module of the edge computing controller. In this step, M=2000. The on-machine measurement result processing module performs the following operations:

[0050] (1) Read the coordinates of the measurement points recorded by the CNC system;

[0051] (2) Call the measurement compensation values ​​(including pre-travel compensation values ​​and ruby ​​ball radius compensation values) generated in advance by the probe calibration program and stored in the macro variable address to accurately correct the coordinates of the measurement point. The principle of the measurement point coordinate correction is referred to Figure 3 and Figure 4 ;

[0052] (3) Using the corrected measurement point coordinates, the actual parameters of the workpiece feature are fitted and generated. In this embodiment, the workpiece feature is a circle, so the actual parameters of the workpiece feature include the X-axis coordinate of the circle center, the Y-axis coordinate of the circle center, and the diameter.

[0053] (4) Store the actual parameters of the workpiece features into the macro variable address defined in the protocol. For example, store the X-axis coordinate of the center of the circle into #6101, the Y-axis coordinate of the center of the circle into #6102, and the diameter into #6103.

[0054] Step 2: Modify the value of the macro variable address M in the main program. In this step, M=3000. Switch to the workpiece shape and size calculation module of the edge computing controller. The workpiece shape and size calculation module performs the following operations:

[0055] (1) Read the theoretical parameters (#5101, #5102, #5103) and the measured parameters (#6101, #6102, #6103) from the macro variable address.

[0056] (2) By comparison, the form and position size deviation of the workpiece is calculated. In this embodiment, the form and position size deviation of the workpiece includes the center position deviation (ΔX, ΔY) and the diameter deviation ΔD.

[0057] Step 3: In the main program, modify the value of the macro variable address M. In this step, M=4000. Switch to the adaptive compensation machining module of the edge computing controller. The adaptive compensation machining module generates coordinate system correction and / or tool compensation based on the form and position dimensional deviation and writes the generated results to their corresponding macro variable addresses, such as #101, #102, and #105. Refer to the compensation principle. Figure 5 .

[0058] Step 4: The main program calls the machining subroutine again. The variable compensation instruction (such as G10) in the machining subroutine automatically calls the latest compensation value in the macro variable address, driving the machine tool to complete the final precision machining, thereby achieving adaptive compensation for machining deviations and forming a closed loop. (Refer to...) Figure 6 If the center of the circle shifts, the machining coordinate system position is adjusted; if the hole diameter deviates, the tool radius is compensated; in actual operation, if the hole depth deviates, the tool length can also be compensated.

[0059] To verify the effectiveness of the present invention, refer to Figure 7 The inventors also applied the traditional compensation machining method (i.e., the "machining-disassembly-offline inspection-manual correction-re-clamping machining" mode) and the method provided in the above embodiments to the machining of turbine disk grooves in typical aero-engine casings; the comparison results of the machining accuracy of the two methods are as follows: Figure 8 As shown, the key features of the workpiece are the first turbine disk groove S1, the second turbine disk groove S2, and the third turbine disk groove S3 (see reference). Figure 7 (a) By applying the compensation method proposed in this invention, the processing accuracy was significantly and consistently improved. This result fully demonstrates that this invention, through the technical path of measurement-calculation-compensation, successfully realizes closed-loop intelligent processing from perception and decision-making to execution, effectively solving the technical problems of reliance on manual labor, low efficiency, and poor consistency in traditional methods.

[0060] The specific embodiments of the present invention are provided to enable those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention.

[0061] It should be understood that the present invention is not limited to the content already described above, and various modifications and changes can be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. A cutting deviation adaptive compensation method driven by digital twin at the edge, characterized in that, The method is based on the execution of pre-stored machining and measurement subroutines in the CNC system, wherein the machining subroutines contain variable compensation instructions; the method includes the following steps: S1. Based on a predefined data interaction protocol, communication is established between the edge computing controller and the CNC system. The edge computing controller is deployed at the edge of the CNC machine tool. The data interaction protocol defines the mapping relationship between workpiece shape and size measurement information and compensation information and macro variable addresses of the CNC system. S2. Execute the measurement subroutine to obtain the coordinates of the measurement points of the actual processing features of the workpiece. Perform error compensation and feature fitting on the coordinates of the measurement points through the edge computing controller to obtain the actual parameters of the workpiece features. Store the actual parameters of the workpiece features in the corresponding macro variable address defined in the data interaction protocol. S3. The edge computing controller reads the actual and theoretical parameters of the workpiece features from the corresponding macro variable address, calculates the form and position dimension deviation of the workpiece, generates the machining coordinate system correction amount and / or tool compensation amount, and writes the generated result into the corresponding macro variable address defined in the data interaction protocol. S4. Execute the machining subroutine, which calls the generated machining coordinate system correction amount and / or tool compensation amount through the variable compensation instruction to achieve adaptive compensation of machining deviation.

2. The edge-end digital twin-driven cutting deviation adaptive compensation method according to claim 1, characterized in that, The edge computing controller is equipped with an edge-to-end data interaction module, an on-machine measurement result processing module, a workpiece shape and size calculation module, and an adaptive compensation machining module; the automatic switching of each functional module is controlled by the numerical information in the address of a function selection macro variable.

3. The edge-end digital twin-driven cutting deviation adaptive compensation method according to claim 1, characterized in that, In S2, error compensation includes probe pre-stroke error compensation and ruby ​​ball radius compensation. The specific process of error compensation and feature fitting for measurement point coordinates is as follows: call the measurement compensation value generated in advance by the probe calibration program and stored in the macro variable address, correct the measurement point coordinates, and fit the corrected measurement point coordinates to obtain the actual parameters of the workpiece features.

4. The edge-end digital twin-driven cutting deviation adaptive compensation method according to claim 1, characterized in that, In S2, the workpiece feature type includes at least one of point, circle, plane, cylinder, curved surface and groove; in S3, the type of shape and position dimensional deviation includes at least one of distance, angle, roundness, coaxiality, concentricity, flatness, perpendicularity, parallelism and inclination.

5. The edge-end digital twin-driven cutting deviation adaptive compensation method according to claim 1, characterized in that, The variable compensation instruction is a programmable parameter input instruction of the CNC system, which is used to automatically set the value in the macro variable address as the machining coordinate system offset or tool compensation value when the machining subroutine is running.

6. The edge-end digital twin-driven cutting deviation adaptive compensation method according to claim 1, characterized in that, In the data interaction protocol, the mapping relationship between workpiece shape and size measurement information and compensation information and CNC system macro variable addresses is predefined and fixed.

7. The edge-end digital twin-driven cutting deviation adaptive compensation method according to claim 1, characterized in that, The geometrical measurement information includes machine measurement information and geometrical dimension information; the machine measurement information includes the measurement point number, theoretical coordinates, and measured coordinates; the geometrical dimension information includes the type of machining feature, the type of geometrical dimension deviation, and the theoretical geometrical dimension; the compensation information includes the compensation target type, coordinate system correction amount, and tool compensation value.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the steps of the method as described in any one of claims 1 to 7.

9. An edge computing controller, characterized in that, include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the program, implements the steps of the method as described in any one of claims 1 to 7.

10. A CNC machining system, characterized in that, include: The CNC machine tool, the contact-type in-machine measurement probe, and the edge computing controller as described in claim 9; the edge computing controller communicates with the CNC system in the CNC machine tool via an industrial network protocol and performs data interaction using the macro variable address of the CNC system as a medium.

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