System and method for constructing and evaluating digital twin of machine tool

Abstract

The present invention relates to a system and method for constructing and evaluating a digital twin of a machine tool, wherein a transient area for a selected transfer system is derived and a digital twin is constructed by using only data in which dynamic characteristics are reflected in the derived transient area, thereby reducing construction time and costs of the digital twin and improving worker convenience, and a digital twin constructed for each selected transfer system is evaluated or a digital twin constructed for each actual specific-shape machining is evaluated after constructing the digital twin for the selected transfer system, thereby maximizing the accuracy and similarity of the constructed digital twin, improving stability and reliability, and preventing resource waste.

Description

Digital Twin Construction and Evaluation System for Machine Tools and Method for Construction and Evaluation thereof

[0001] The present invention relates to a digital twin construction and evaluation system for a machine tool and a method for constructing and evaluating the same. More specifically, it relates to a digital twin construction and evaluation system for a machine tool and a method for constructing and evaluating the same that can maximize the accuracy and similarity of a digital twin while reducing the time and cost of constructing the digital twin by deriving a transient region for a selected feed system, constructing a digital twin using only the data of the transient region reflecting dynamic characteristics, and evaluating the digital twin constructed for each selected feed system or evaluating the digital twin constructed for each actual specific shape machining.

[0002] Generally, a machine tool refers to a machine used for the purpose of processing metal or non-metal workpieces into a desired shape and dimensions using a suitable tool through various cutting or non-cutting methods.

[0003] Various types of machine tools, including turning centers, vertical / horizontal machining centers, gantry machining centers, Swiss turns, electrical discharge machining machines, horizontal NC boring machines, and CNC lathes, are widely used in various industrial sites to suit the specific tasks of the operation.

[0004] In addition, the machine tool is equipped with a table on which a material serving as a workpiece is placed and which is transported for processing the workpiece, a pallet for preparing the workpiece before processing, a spindle on which a tool or workpiece is combined and rotates, a tailstock for supporting the workpiece during processing, a vibration dampener, etc.

[0005] Generally, in machine tools, the table, tool holder, spindle, tailstock, and dust collector are equipped with a feed system that moves along a feed axis to perform various machining operations. Depending on the type of machine tool, such a feed system can be formed in various ways, such as 2-axis, 3-axis, 4-axis, or 5-axis.

[0006] In addition, machine tools generally use multiple tools for various processing operations, and tool magazines or turrets are used as tool storage areas for storing multiple tools.

[0007] In addition, machine tools are generally equipped with an Automatic Tool Changer (ATC) to retrieve or re-store specific tools from a tool magazine by command from a numerical control unit in order to improve the productivity of the machine tool.

[0008] In addition, machine tools are generally equipped with an Automatic Palette Changer (APC) to minimize non-processing time. The APC automatically exchanges pallets between the workpiece processing area and the workpiece installation area. Workpieces can be loaded onto the pallets.

[0009] In general, numerical control (NC) is rapidly advancing in the various types of machine tools currently in use.

[0010] Recently, as machine tools are automatically controlled using computers equipped with numerical control (NC), there is a rapidly growing trend of machine tools equipped with computerized numerical control (CNC) technology, which is a further advancement of numerical control.

[0011] Numerical control (NC) or computer numeric control (CNC) machine tools are equipped with control panels. These control panels are equipped with various function switches or buttons and monitors.

[0012] As such, machine tools equipped with numerical control or computer numerical control perform machining of a workpiece by moving the feed system according to numerical control commands.

[0013] However, nowadays, when performing actual workpiece machining tests to execute precision or high-speed machining, there were problems such as the consumption of time and cost, difficulty in predicting accuracy and repeatability due to changes in dynamic characteristics during operation, and waste of resources.

[0014] To address these issues, Digital Twin technology has been introduced to replicate real-world objects, systems, and environments in a virtual space. Through this, there is a movement to design, monitor, and optimize machine tools using Digital Twins, just as in other technology fields.

[0015] The superficial form of a digital twin appears to be the creation of a physical object in the real world as a twin virtual object in the virtual world, and the performance of the physical object's movements and behaviors as a role model for the twin virtual object, thereby enabling the simulation and modeling of the real world within the virtual world.

[0016] However, conventional digital twin construction and evaluation systems and methods for machine tools have had a problem in that accuracy and approximation have not been significantly improved, despite the fact that the large amount of data required to build the digital twin—which consumes a significant amount of time and cost and causes inconvenience to operators—and the digital twin is constructed based on numerical analysis by collecting and utilizing both position commands and feedback data from repetitive reciprocating motions performed on the feed system, due to the difficulty in measuring or assessing the dynamic characteristics of the machine tool's feed system.

[0017] In addition, conventional digital twin construction systems for machine tools simply construct various digital twins of the machine tool using collected information and fail to reflect changes in various dynamic characteristics occurring in the actual machine tool. Furthermore, there was a problem in that the accuracy and approximation of the digital twin constructed by reflecting changes in dynamic characteristics were not evaluated, or even if an evaluation was conducted, the reliability was low, which led to a decrease in the stability and reliability of the system.

[0018] The present invention aims to solve the above-mentioned problems. The objective of the present invention is to provide a digital twin construction and evaluation system for a machine tool and a method for construction and evaluation thereof, which can reduce the time and cost of constructing a digital twin and improve the convenience of the operator by deriving a transient region for a selected transfer system and constructing a digital twin using only the data of the transient region reflecting dynamic characteristics, and by evaluating the digital twin constructed for each selected transfer system or the digital twin constructed for each actual specific shape machining after constructing the digital twin for the selected transfer system, thereby maximizing the accuracy and similarity of the constructed digital twin, improving stability and reliability, and preventing resource waste.

[0019] To achieve the objective of the present invention, the digital twin construction and evaluation system for a machine tool according to the present invention comprises: a machine tool having one or more feed systems and processing a workpiece; and a digital twin construction unit connected to the machine tool via a network and constructing a digital twin for a feed system selected among the feed systems of the machine tool; wherein the digital twin construction unit derives a transient region for the selected feed system and can construct a digital twin by utilizing only the data of the transient region in which dynamic characteristics are reflected.

[0020] In addition, in another preferred embodiment of the digital twin construction and evaluation system for a machine tool according to the present invention, the digital twin construction and evaluation system for a machine tool may further include a digital twin evaluation unit that evaluates a digital twin constructed through the digital twin construction unit, and is connected to the machine tool and the digital twin construction unit via a network.

[0021] In addition, in another preferred embodiment of the digital twin construction and evaluation system for a machine tool according to the present invention, the digital twin evaluation unit of the digital twin construction and evaluation system for a machine tool can evaluate each selected feed system by examining the difference in error values ​​for each feed system between the digital twin constructed for each feed system selected by the digital twin construction unit and the actual machine tool.

[0022] In addition, in another preferred embodiment of the digital twin construction and evaluation system for a machine tool according to the present invention, the digital twin evaluation unit of the digital twin construction and evaluation system for a machine tool can evaluate each actual specific shape machining by reflecting reference shape information and tool information or machining surface information for the specific shape to be actually machined during actual specific shape machining, and analyzing the reference shape information and correction values ​​of the actual machine tool with the digital twin constructed through the digital twin construction unit.

[0023] In addition, in another preferred embodiment of the digital twin construction and evaluation system for a machine tool according to the present invention, the digital twin construction unit of the digital twin construction and evaluation system for a machine tool comprises: a database unit that stores one or more data among feed system information, feed speed information, reference error value, machining program, or driving program data to construct a digital twin for a selected feed system; a selection unit that selects one or more feed systems among the feed systems of the machine tool through the data stored in the database unit; a determination unit that determines the feed speed of the selected feed system according to the selection result of the selection unit and the data stored in the database unit; a generation unit that generates reference input information according to the determination result of the determination unit and the data stored in the database unit; a calculation unit that calculates the rate of change of position according to the generation result of the generation unit and the data stored in the database unit; an acquisition unit that acquires position feedback information by actually driving the machine tool for the feed system selected by the selection unit using the reference input information based on the generation result of the generation unit; and a calculation unit that calculates the rate of change of position feedback according to the acquisition result of the acquisition unit and the data stored in the database unit. The apparatus includes: a calculation unit that calculates the error values ​​of the position change rate and the position feedback change rate according to the calculation result of the calculation unit and the calculation result of the operation unit; a comparison unit that compares the error value according to the calculation result of the calculation unit with the reference error value stored in the database unit; a derivation unit that derives the period from the point where the error value deviates from the reference error value to the point where the reference error value is satisfied according to the comparison result of the comparison unit as a transient region; an identification unit that identifies the dynamic characteristic parameters of the selected transport system through the reference input information and position feedback information corresponding to the transient region derived according to the derivation result of the derivation unit; and a construction unit that constructs a digital twin for the selected transport system using the transient region information to which the dynamic characteristic parameters are applied according to the identification result of the identification unit.

[0024] In addition, in another preferred embodiment of the digital twin construction and evaluation system for a machine tool according to the present invention, the determining unit of the digital twin construction and evaluation system for a machine tool may determine the feed speed of a selected feed system as an equal value or a representative value within the feed speed range.

[0025] In addition, in another preferred embodiment of the digital twin construction and evaluation system for a machine tool according to the present invention, the generation unit of the digital twin construction and evaluation system for a machine tool can generate a tilt input using position input information over time.

[0026] In addition, in another preferred embodiment of the digital twin construction and evaluation system for a machine tool according to the present invention, the identification unit of the digital twin construction and evaluation system for a machine tool may have dynamic characteristic parameters identified and selected through a genetic algorithm for each feed system selected through the selection unit.

[0027] In addition, in another preferred embodiment of the digital twin construction and evaluation system for a machine tool according to the present invention, the digital twin evaluation unit of the digital twin construction and evaluation system for a machine tool may include: a storage module that stores one or more data among reference error values, reference shape information, tool information, and machining surface information for a workpiece to be actually machined, or reference correction values ​​for evaluating the constructed digital twin; a judgment unit that determines whether to evaluate by selected feed system or by actual specific shape machining; an error value calculation unit that calculates a digital twin error value resulting from the error between the input value applied to the constructed digital twin and the output value resulting from the operation of the constructed digital twin when evaluating by selected feed system as a result of the judgment unit, and an actual machine tool error value resulting from the error between the input value applied to the actual machine tool and the output value resulting from the operation of the actual machine tool; and a selected feed system evaluation unit that evaluates the digital twin by selected feed system by comparing and analyzing the difference between the digital twin error value and the actual machine tool error value according to the calculation result of the error value calculation unit with the reference error value stored in the storage module.

[0028] In addition, in another preferred embodiment of the digital twin construction and evaluation system for a machine tool according to the present invention, the digital twin evaluation unit of the digital twin construction and evaluation system for a machine tool comprises: a verification unit that verifies reference shape information and tool information or machining surface information according to the actual specific shape to be machined when evaluating by actual specific shape machining based on the judgment result of the judgment unit; a modification unit that modifies the input value applied to the digital twin constructed according to the verification result of the verification unit and the data stored in the storage module and the input value applied to the actual machine tool by reflecting the reference shape information, tool information, and machining surface information; and a correction value calculation unit that calculates a digital twin correction value based on the error between the modified input value applied to the digital twin and the output value resulting from the operation of the digital twin, and an actual machine tool correction value based on the error between the modified input value applied to the actual machine tool and the output value resulting from the operation of the actual machine tool, based on the modification result of the modification unit and the data stored in the storage module. and may further include an evaluation unit for each actual specific shape machining that evaluates the digital twin for each actual specific shape machining by comparing and analyzing the difference between the digital twin correction value and the actual machine tool correction value according to the calculation result of the correction value calculation unit with the reference correction value and reference shape information stored in the storage module.

[0029] To achieve another objective of the present invention, the method for constructing and evaluating a digital twin of a machine tool according to the present invention may include: a step of constructing a digital twin and storing data for evaluating the constructed digital twin; a step of deriving a transient region for a selected feed system among the feed systems of a machine tool that processes a workpiece having one or more feed systems, and constructing a digital twin by utilizing only the data of the transient region in which dynamic characteristics are reflected; and a step of evaluating the constructed digital twin.

[0030] In addition, in another preferred embodiment of the method for constructing and evaluating a digital twin of a machine tool according to the present invention, the step of constructing the digital twin of the method for constructing and evaluating a digital twin of a machine tool comprises: a step of selecting one or more feed systems among the feed systems of the machine tool; a step of determining the feed speed of the selected feed system according to the selection result and previously stored data; a step of generating reference input information according to the determination result and previously stored data; a step of calculating the rate of change of position according to the generation result and previously stored data; a step of actually driving the machine tool for the feed system selected in the selection step using the reference input information based on the generation result to acquire position feedback information; a step of calculating the rate of change of position feedback according to the acquisition result and previously stored data; a step of calculating the error value between the rate of change of position and the rate of change of position feedback according to the calculation result and the calculation result; a step of comparing the calculated error value with a previously stored reference error value; and a step of deriving the period from the point where the error value deviates from the reference error value to the point where it satisfies the reference error value according to the comparison result as a transient region. The method may include: a step of identifying dynamic characteristic parameters of a selected transport system through reference input information and position feedback information corresponding to the derived transient region; and a step of constructing a digital twin of the selected transport system using transient region information to which dynamic characteristic parameters are applied according to the identification result.

[0031] In addition, in another preferred embodiment of the method for constructing and evaluating a digital twin of a machine tool according to the present invention, the step of evaluating the constructed digital twin of the method for constructing and evaluating a digital twin of a machine tool may include: a step of determining whether to evaluate by selected feed system or by actual specific shape machining; a step of calculating a digital twin error value resulting from the error between the input value applied to the constructed digital twin and the output value resulting from the operation of the constructed digital twin when evaluating by selected feed system as a result of the determination, and an actual machine tool error value resulting from the error between the input value applied to the actual machine tool and the output value resulting from the operation of the actual machine tool; and a step of evaluating the digital twin by selected feed system by comparing and analyzing the difference between the digital twin error value and the actual machine tool error value based on the error value calculation result with a previously stored reference error value.

[0032] In addition, in another preferred embodiment of the method for constructing and evaluating a digital twin of a machine tool according to the present invention, the step of evaluating the constructed digital twin of the method for constructing and evaluating a digital twin of a machine tool may include, after the judgment step, a step of verifying reference shape information and tool information or machining surface information according to the actual specific shape to be machined when evaluating by actual specific shape machining as a result of judgment; a step of modifying the input value applied to the constructed digital twin and the input value applied to the actual machine tool according to the verification result and the previously stored data by reflecting the reference shape information, tool information, and machining surface information; a step of calculating a digital twin correction value based on the error between the modified input value applied to the constructed digital twin and the output value according to the operation of the constructed digital twin according to the modification result and the previously stored data, and an actual machine tool correction value based on the error between the modified input value applied to the actual machine tool and the output value according to the operation of the actual machine tool; and a step of evaluating the digital twin by comparing and analyzing the difference between the digital twin correction value and the actual machine tool correction value according to the correction value calculation result with the previously stored reference correction value and reference shape information.

[0033] The digital twin construction and evaluation system for a machine tool and the method for construction and evaluation thereof according to the present invention have the effect of reducing the time and cost of constructing the digital twin by deriving a transient region for a selected feed system and utilizing only the data of the transient region that reflects dynamic characteristics.

[0034] In addition, the digital twin construction and evaluation system for machine tools and the method for construction and evaluation according to the present invention can use existing programs to reflect dynamic characteristics, thereby increasing compatibility and minimizing the occurrence of errors, which has the effect of promoting convenience for the operator.

[0035] Furthermore, the digital twin construction and evaluation system for a machine tool and the method for construction and evaluation thereof according to the present invention have the effect of maximizing the accuracy and similarity of the constructed digital twin by evaluating the digital twin constructed for each selected feed system or evaluating the digital twin constructed for each actual specific shape machining after constructing a digital twin for a selected feed system.

[0036] Furthermore, the digital twin construction and evaluation system for a machine tool and the method for construction and evaluation according to the present invention have the effect of improving the reliability and stability of the digital twin for a selected feed system, thereby maximizing the satisfaction of consumers and operators and preventing resource waste.

[0037] Figure 1 shows a conceptual diagram of a digital twin construction and evaluation system for a machine tool according to the present invention.

[0038] Figure 2 shows a configuration diagram of a digital twin construction and evaluation system for a machine tool according to one embodiment of the present invention.

[0039] FIG. 3 shows an example of a machine tool in a digital twin construction and evaluation system for a machine tool according to one embodiment of the present invention.

[0040] Figure 4 shows a graph for reflecting the dynamic characteristics of a digital twin construction and evaluation system for a machine tool according to one embodiment of the present invention.

[0041] Figure 5 shows an example of a digital twin constructed through a digital twin construction and evaluation system for a machine tool according to an embodiment of the present invention.

[0042] FIG. 6 shows a configuration diagram of a digital twin construction unit of a digital twin construction and evaluation system for a machine tool according to one embodiment of the present invention.

[0043] FIG. 7 shows a configuration diagram of a digital twin evaluation unit of a digital twin construction and evaluation system for a machine tool according to one embodiment of the present invention.

[0044] FIG. 8 shows an example of a feed system model according to the selection of an X-axis feed system in the selection section of a digital twin construction and evaluation system for a machine tool according to one embodiment of the present invention.

[0045] FIG. 9 shows an example of a feed system model according to the selection of the Y-axis feed system in the selection section of a digital twin construction and evaluation system for a machine tool according to one embodiment of the present invention.

[0046] FIG. 10 shows an example of a feed system model according to the selection of a Z-axis feed system in the selection section of a digital twin construction and evaluation system for a machine tool according to one embodiment of the present invention.

[0047] Figure 11 shows the definitions and diagrams of variables, etc. for the models of Figures 8 and 9.

[0048] FIGS. 12a, FIGS. 12b, and FIGS. 12c show graphs for step input, slope input, and parabolic input, respectively, when generating reference input information in the generation unit of a digital twin construction and evaluation system for a machine tool according to one embodiment of the present invention.

[0049] Figure 13 shows a graph of the evaluation results for each selected feed system through the digital twin evaluation unit of the digital twin construction and evaluation system of a machine tool according to one embodiment of the present invention.

[0050] FIGS. 14 and 15 show graphs of evaluation results for actual specific shape machining through a digital twin evaluation unit of a digital twin construction and evaluation system for a machine tool according to one embodiment of the present invention.

[0051] Figure 16 shows a flowchart of the method for constructing and evaluating a digital twin of a machine tool according to the present invention.

[0052] FIG. 17 shows a flowchart of the digital twin construction step of the method for constructing and evaluating a digital twin of a machine tool according to one embodiment of the present invention.

[0053] FIG. 18 shows a flowchart of the digital twin evaluation step of the digital twin construction and evaluation method of a machine tool according to one embodiment of the present invention.

[0054] Hereinafter, a digital twin construction and evaluation system for a machine tool and a method for constructing and evaluating the same according to an embodiment of the present invention will be described in detail with reference to the drawings. The embodiments introduced below are provided as examples to ensure that the concept of the present invention is sufficiently conveyed to those skilled in the art. Accordingly, the present invention is not limited to the embodiments described below and may be embodied in other forms. Also, in the drawings, the size and thickness of the device, etc., may be exaggerated for convenience. Throughout the specification, the same reference numerals indicate the same components.

[0055] The present invention is capable of various modifications and may have various embodiments; therefore, specific embodiments are illustrated in the drawings and described in detail in the detailed description. The effects and features of the present invention, and the methods for achieving them, will become clear by referring to the embodiments described in detail below together with the drawings. However, the present invention is not limited to the embodiments disclosed below but can be implemented in various forms. In the following embodiments, terms such as "first," "second," etc., are used not in a limiting sense but for the purpose of distinguishing one component from another. Furthermore, singular expressions include plural expressions unless the context clearly indicates otherwise. Also, terms such as "include" or "have" mean that the features or components described in the specification exist, and do not preclude the possibility that one or more other features or components may be added. Additionally, in the drawings, the size of components may be exaggerated or reduced for convenience of explanation. For example, the size and thickness of each component shown in the drawings are arbitrarily depicted for convenience of explanation, so the present invention is not necessarily limited to what is illustrated.

[0056] The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below but may be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims. Throughout the specification, the same reference numerals refer to the same components. In the drawings, the sizes and relative sizes of layers and regions may be exaggerated for clarity of description.

[0057] The terms used herein are for describing embodiments and are therefore not intended to limit the invention. In this specification, the singular form includes the plural form unless specifically stated otherwise in the text. As used in this specification, "comprise" and / or "comprising" do not exclude the presence or addition of one or more other components, steps, actions, and / or elements to the mentioned components, steps, actions, and / or elements.

[0058] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings. When describing with reference to the drawings, identical or corresponding components are given the same reference numerals, and redundant descriptions thereof will be omitted.

[0059] FIG. 1 shows a conceptual diagram of a digital twin construction and evaluation system for a machine tool according to the present invention, and FIG. 2 shows a configuration diagram of a digital twin construction and evaluation system for a machine tool according to an embodiment of the present invention. FIG. 3 shows an example of a machine tool of a digital twin construction and evaluation system for a machine tool according to an embodiment of the present invention. FIG. 4 shows a graph for reflecting the dynamic characteristics of a digital twin construction and evaluation system for a machine tool according to an embodiment of the present invention. FIG. 5 shows an example of a digital twin constructed through a digital twin construction and evaluation system for a machine tool according to an embodiment of the present invention. FIG. 6 shows a configuration diagram of a digital twin construction unit of a digital twin construction and evaluation system for a machine tool according to an embodiment of the present invention. FIG. 7 shows a configuration diagram of a digital twin evaluation unit of a digital twin construction and evaluation system for a machine tool according to an embodiment of the present invention. FIG. 8 shows an example of a feed system model according to the selection of an X-axis feed system in the selection unit of a digital twin construction and evaluation system for a machine tool according to an embodiment of the present invention. FIG. 9 illustrates an example of a feed system model based on the selection of a Y-axis feed system in the selection unit of a digital twin construction and evaluation system for a machine tool according to an embodiment of the present invention. FIG. 10 illustrates an example of a feed system model based on the selection of a Z-axis feed system in the selection unit of a digital twin construction and evaluation system for a machine tool according to an embodiment of the present invention. FIG. 11 illustrates definitions and diagrams regarding variables, etc., for the models of FIG. 8 and FIG. 9. FIG. 12a, FIG. 12b, and FIG. 12c illustrate graphs for step input, slope input, and parabolic input, respectively, when generating reference input information in the generation unit of a digital twin construction and evaluation system for a machine tool according to an embodiment of the present invention. FIG. 13 illustrates a graph of evaluation results for each selected feed system through the digital twin evaluation unit of a digital twin construction and evaluation system for a machine tool according to an embodiment of the present invention.FIGS. 14 and 15 show graphs of evaluation results for actual specific shape machining through a digital twin evaluation unit of a digital twin construction and evaluation system for a machine tool according to an embodiment of the present invention. FIG. 16 shows a flowchart of a method for constructing and evaluating a digital twin of a machine tool according to the present invention. FIG. 17 shows a flowchart of the digital twin construction step of the method for constructing and evaluating a digital twin of a machine tool according to an embodiment of the present invention. FIG. 18 shows a flowchart of the digital twin evaluation step of the method for constructing and evaluating a digital twin of a machine tool according to an embodiment of the present invention.

[0060] A digital twin construction and evaluation system (1) for a machine tool according to the present invention will be described with reference to FIGS. 1 to FIGS. 15. As shown in FIGS. 1 to 7, the digital twin construction and evaluation system (1) for a machine tool according to the present invention includes a machine tool (100), a digital twin construction unit (200), and a digital twin evaluation unit (300).

[0061] A machine tool (100) is equipped with one or more feed systems and processes a workpiece. That is, as shown in FIG. 3, a machine tool or test bed is equipped with one or more feed systems, which are feed axes, and FIG. 3 discloses a machine tool equipped with three feed systems, such as an X-axis (X-Axis), a Y-axis (Y-Axis), and a Z-axis (Z-Axis), as an example.

[0062] However, it is not necessarily limited to this, and as shown in FIG. 2, the machine tool may be formed in the form of a 4-axis, 5-axis, etc., additionally equipped with a C-axis, A-axis, B-axis, etc., as needed.

[0063] In addition, the machine tool includes an NC control unit (120) composed of NC (numerical control) or CNC (computerized numerical control), and has various numerical control programs built in. In addition, although not shown in the drawings, according to a preferred embodiment of the present invention, the NC control unit includes a main operation unit, and this main operation unit includes a screen display program and a data input program based on the screen display selection, and performs the function of displaying a software switch on a display screen according to the output of the screen display program, and recognizing the ON / OFF of the software switch to issue input / output commands for machine operation.

[0064] In addition, although not necessarily limited thereto, the main operating unit is installed on the housing, case, or one side of the machine tool and is equipped with various function switches or buttons and a monitor capable of displaying various information.

[0065] The digital twin construction unit (200) is connected to the machine tool via a network and constructs a digital twin for a selected feed system among the feed systems of the machine tool.

[0066] That is, as illustrated in FIG. 5, the digital twin construction unit (200) can select one or more feed systems from among the feed systems of the machine tool and construct a digital twin (201) for the selected feed system.

[0067] The digital twin evaluation unit (300) is connected to the machine tool and the digital twin construction unit via a network, and evaluates the digital twin constructed through the digital twin construction unit.

[0068] The digital twin construction unit of the digital twin construction and evaluation system for a machine tool according to the present invention derives a transient region for a selected feed system and constructs a digital twin by utilizing only the data of the transient region that reflects dynamic characteristics.

[0069] In Figure 4, the horizontal axis represents time (s) and the vertical axis represents the feed rate per minute.

[0070] As illustrated in FIG. 4, the digital twin construction unit of the digital twin construction and evaluation system for a machine tool according to the present invention does not utilize both the transient and steady states of the time and feedback data for the feed amount according to all times between 0 and 0.2 seconds, but rather derives the transient state between 0 and 0.04 seconds for the selected feed system and constructs the digital twin by utilizing only the data of the transient state that reflects dynamic characteristics, thereby reducing the time and cost of constructing the digital twin and improving operator satisfaction.

[0071] The digital twin evaluation unit of the digital twin construction and evaluation system for a machine tool according to the present invention evaluates each selected feed system by examining the difference in error values ​​between the digital twin constructed for each feed system selected by the digital twin construction unit and the actual machine tool for each feed system.

[0072] In addition, the digital twin evaluation unit of the digital twin construction and evaluation system for a machine tool according to the present invention evaluates each actual specific shape machining by reflecting reference shape information and tool information or machining surface information for the specific shape to be machined during actual specific shape machining, analyzing the reference shape information and correction values ​​of the actual machine tool with the digital twin constructed through the digital twin construction unit.

[0073] Thus, the digital twin construction and evaluation system for a machine tool according to the present invention can maximize the accuracy and similarity of the constructed digital twin, improve stability and reliability, and prevent resource waste by evaluating the digital twin constructed for each selected feed system or evaluating the digital twin constructed for each actual specific shape machining after constructing a digital twin for a selected feed system.

[0074] A network connecting a machine tool, a digital twin construction unit, and a digital twin evaluation unit refers to a connection structure capable of exchanging information between each node. Examples of such a network include, but are not limited to, LTE (Long Term Evolution) networks, WIMAX (World Interoperability for Microwave Access) networks, the Internet, LAN (Local Area Network), Wireless LAN (Wireless Local Area Network), WAN (Wide Area Network), PAN (Personal Area Network), and Bluetooth networks.

[0075] As illustrated in FIGS. 1 to 2 and FIGS. 6, the digital twin construction unit (200) of the digital twin construction and evaluation system (1) of the machine tool according to the present invention includes a database unit (210), a selection unit (215), a decision unit (220), a generation unit (225), a calculation unit (230), an acquisition unit (240), an operation unit (245), a calculation unit (250), a comparison unit (260), a derivation unit (270), an identification unit (280), and a construction unit (290).

[0076] The database unit (210) stores one or more data among data for transfer system information, transfer speed information, reference error value, processing program, or driving program in order to build a digital twin for the selected transfer system. Preferably, the database unit stores all data for transfer system information, transfer speed information, reference error value, processing program, and driving program in order to build a digital twin for the selected transfer system.

[0077] The database unit can be various storage devices such as ROM, RAM, EPROM, flash drives, hard drives, etc., and can also be web storage that performs the storage function of the memory unit on the internet.

[0078] The selection unit (215) selects one or more feed systems from the feed systems of the machine tool through data stored in the database unit.

[0079] That is, when the selection unit selects one or more axes of the feed systems of the machine tool through data stored in the database unit, the feed system model for the corresponding axis is determined together, as shown in FIGS. 8 to 11.

[0080] In FIG. 11, symbols and units for a machine tool feed system model including the X-axis, Y-axis, and Z-axis three-axis feed system of FIG. 8 to 10 are shown.

[0081] Specifically, when the X-axis is selected as the transfer system in the selection section, the X-axis transfer system model of Fig. 8 is applied, and mass-related dynamic parameter for friction and plant value is applied to the calculated transient region to construct a digital twin.

[0082] In addition, when the Y-axis is selected as the transport system in the selection section, the Y-axis transport system model of Fig. 9 is applied, and mass-related dynamic parameter for friction and plant value is applied to the calculated transient region to construct a digital twin.

[0083] In addition, when the Z-axis is selected as the transfer system in the selection section, the Z-axis transfer system model of Fig. 10 is applied to the transient region calculated with added dynamic parameter for mass and friction and plant value and dynamic parameter related to gravitational acceleration to construct a digital twin.

[0084] The decision unit (220) determines the transfer speed of the selected transfer system according to the selection result of the selection unit and the data stored in the database unit.

[0085] According to one embodiment of the present invention, the determining unit determines the transfer speed of a selected transfer system as an equal value or a representative value within a transfer speed range.

[0086] Specifically, when the decision unit selects an X-axis feed system and constructs a digital twin for the X-axis feed system, if the feed speed of the X-axis feed system stored in the database unit is 0 mm / min to 1200 mm / min, the decision unit may determine the feed speed as 300 mm / min, 600 mm / min, 900 mm / min, and 1200 mm / min, which are divided into four parts, or determine the feed speed as 600 mm / min and 1200 mm / min, which are divided into two parts, in order to construct a digital twin for the feed speed.

[0087] Alternatively, when the decision unit selects an X-axis feed system and constructs a digital twin for the X-axis feed system, if the feed speed of the X-axis feed system stored in the database unit is 0 mm / min to 1200 mm / min, the decision unit may determine 600 mm / min as the feed speed as a representative value to construct a digital twin for the feed speed.

[0088] These equal division values ​​and representative values ​​may vary depending on the type of machine tool and the feed coefficient, etc.

[0089] The generation unit (225) generates standard input information based on the decision result of the decision unit and the data stored in the database unit.

[0090] Preferably, as shown in FIG. 12, the generator generates the position input information over time through slope input.

[0091] That is, the transfer speed determined in the determination unit is generated as a position over time with a slope, and the reference input information is generated as a transfer command in the form of a linear function.

[0092] The influence of the mass and frictional force of the transport system, which are dynamic characteristic identification parameters, is more pronounced in the slope input of Fig. 12b than in the parabolic input of Fig. 12c, and more pronounced in the step input of Fig. 12a than in the slope input of Fig. 12b. For reference, in Fig. 12, P represents position and t represents time.

[0093] However, if the step input of Fig. 12a is used as a feed command, the machine tool may be subjected to impact. Therefore, the inclined input, which minimizes impact on the machine while highlighting the influence of mass and friction, is the most effective. By utilizing this reference input information as a reference inclined input, a digital twin can be constructed using a transient region to which dynamic characteristic identification parameters are applied, thereby enabling the construction of a digital twin that is fast, accurate, and stable.

[0094] Specifically, when a digital twin for an X-axis feed system is constructed by selecting an X-axis feed system through a determination unit, and the feed speed of the X-axis feed system stored in the database unit is 0 mm / min to 1200 mm / min, and the feed speed is determined to be 300 mm / min, 600 mm / min, 900 mm / min, and 1200 mm / min, the reference slope input is 5 mm, 10 mm, 15 mm, and 20 mm per second, which means the moving position input per second.

[0095] The calculation unit (230) calculates the rate of change in position based on the generation result of the generation unit and the data stored in the database unit.

[0096] In other words, the calculation unit calculates the amount of position change over time while the reference input information is generated as a reference slope input through the generation unit. This is intended to be used when setting the transient region.

[0097] Specifically, the calculation unit calculates the reference slope input of 5mm, 10mm, 15mm, and 20mm per second by dividing it again by the second, and the rate of change of position (α) calculated through the calculation unit becomes 5mm / s, 10mm / s, 15mm / s, and 20mm / s.

[0098] The acquisition unit (240) acquires position feedback information by actually driving the machine tool for the transfer system selected in the selection unit using the reference input information based on the generation result of the generation unit.

[0099] In other words, the acquisition unit drives the machine tool using the reference inclination input, which is the reference input information based on the generation result of the generation unit, and acquires position feedback information, which is the actual position of the feed system over time.

[0100] Here, position feedback information is position data from the point where the actual feed system's feed starts to the point where it ends over time by driving the machine tool with reference inclination input, for example, the position feedback information is from 0 to 20 mm.

[0101] The calculation unit (245) calculates the position feedback change rate (β) based on the acquisition result of the acquisition unit and the data stored in the database unit.

[0102] In other words, the calculation unit calculates the position feedback information acquired through the acquisition unit as a velocity, which is the rate of change of position over time. Ultimately, the rate of change of position feedback is calculated as velocity through the calculation unit.

[0103] For example, the rate of change of position feedback gradually increases from 0 mm / s to 5 mm / s, from 5 mm / s to 10 mm / s, from 10 mm / s to 15 mm / s, and from 15 mm / s to 20 mm / s.

[0104] The calculation unit (250) calculates the error value (γ) (position change rate (α) - position feedback change rate (β)) of the position change rate (α) and the position feedback change rate (β) according to the calculation result of the calculation unit and the calculation result of the operation unit.

[0105] The comparison unit (260) compares the error value (γ) based on the calculation result of the calculation unit with the reference error value stored in the database unit.

[0106] The derivation unit (270) derives the period from the point where the error value deviates from the reference error value according to the comparison result of the comparison unit until the point where the reference error value is satisfied as an excessive region.

[0107] For example, if the reference error value stored in the database is 2%, the data from the time of data acquisition until the time when the error value (γ) becomes 2% or less is derived as the transient region of the selected transfer system according to the set data acquisition range.

[0108] That is, as shown in Fig. 4, since the influence of the mass and frictional force of the transport system, which are dynamic characteristic identification parameters, is predominantly present in the position feedback of the transient region, the dynamic characteristic parameters can be identified by utilizing only the data of the transient region, rather than the data of the entire region up to the steady state.

[0109] The identification unit (280) identifies the dynamic characteristic parameters of the selected transport system through reference input information and position feedback information corresponding to the transient region derived according to the result of the derivation unit.

[0110] In an embodiment of the present invention, the identification unit identifies and selects dynamic characteristic parameters through a genetic algorithm for each transport system selected through the selection unit.

[0111] Specifically, the genetic algorithm identifies dynamic parameter values ​​through a total of seven processes.

[0112] The first process (Initialize population) sets the upper and lower limits of the parameters to be identified. That is, to perform a stable optimization process, the upper and lower limits of the parameters to be identified are arbitrarily set.

[0113] The second process (Population update) involves setting the initial population size, determining the number of individuals constituting a generation by considering the accuracy and convergence time of the genetic algorithm. Specifically, within the range satisfying the upper and lower limits set in the first process, a number of individuals (parameter pairs) corresponding to the set population size are randomly selected to form a generation.

[0114] The third process (Evaluation) is evaluation. It calculates the objective function values ​​of the entities determined in the second process.

[0115] The objective function is defined as Equation 1 by utilizing the number of weights, maximum prediction error, average prediction error, applied transfer speed, and applied transfer speed.

[0116] The maximum prediction error and average prediction error refer to the maximum and average values ​​of the difference in predicted location values ​​when applying the entities determined in the second process to the acquired location feedback.

[0117] [Equation 1]

[0118]

[0119] The fourth process (Selection) is selection, which evaluates the performance of each individual based on the objective function value and utilizes a Roulette wheel selection algorithm so that the probability of each individual being selected for the next generation is proportional to its performance.

[0120] The fifth step (Termination Check) verifies the identification termination conditions; considering the accuracy and convergence time of the genetic algorithm, the allowable variation of the objective function between generations and the maximum number of generations are arbitrarily determined. If neither the conditions for the allowable variation of the objective function between generations nor the maximum number of generations are satisfied, the sixth step is performed.

[0121] Process 6 (Offspring) involves the creation of a new generation, randomly determining the proportion of entities to be newly created in the next generation through Elite count, crossover, and mutation. Elite count is determined from the entities generated in the previous generation, crossover is performed by crossing entities selected in Process 4, and mutation involves randomly generating entities within the range restricted in Process 1 to be reflected in the next generation.

[0122] The seventh step (Return result) involves termination and result return; if the identification termination condition of the fifth step is satisfied, the object that minimizes the objective function is selected as the parameter identification result.

[0123] The construction unit (290) constructs a digital twin of the selected transport system by utilizing the transient region information to which dynamic characteristic parameters are applied according to the identification result of the identification unit.

[0124] Specifically, the transient region is derived and stored, and to apply a genetic algorithm to the derived transient region information, the upper and lower limits of mass are set to 10 kg and 100 kg, respectively, the upper and lower limits of friction force are set to 0 N and 100 N, respectively, and the number of individuals is set to 10, and the initial values ​​are set to mass 10 kg and friction force 0 N, respectively. Within the set range of mass and friction force, 10 individuals are randomly selected, and the objective function value is calculated. For example, considering that the number of applied transport speeds is 4 (300 mm / min, 600 mm / min, 900 mm / min, 1200 mm / min), weights w1 and w2 are set to 1 / 16 and 3 / 16, respectively, and if the position prediction error at each transport speed is calculated as shown in Table 1, the objective function value is calculated using Equation 2.

[0125] Feed rate 300 mm / min Maximum position prediction error Average position prediction error Apply initial value 30 10 Apply value of the corresponding object 25 5 Feed rate 600 mm / min Maximum position prediction error Average position prediction error Apply initial value 60 40 Apply value of the corresponding object 55 35 Feed rate 900 mm / min Maximum position prediction error Average position prediction error Apply initial value 90 70 Apply value of the corresponding object 85 65 Feed rate 1200 mm / min Maximum position prediction error Average position prediction error Apply initial value 120 100 Apply value of the corresponding object 11 5 95

[0126] [Equation 2]

[0127] (1 / 16×25 / 30+3 / 16×5 / 10)+(1 / 16×55 / 60+3 / 16×35 / 40)+(1 / 16×85 / 90+3 / 16×65 / 70)+(1 / 16×115 / 120+3 / 16×95 / 100)

[0128] Based on the objective function values ​​calculated in this way, the performance of each individual is evaluated, and the individual to be assigned to the next generation is selected using the Roulette wheel selection algorithm. The allowable change between generations of the objective function is set to 0.0001, and the maximum number of generations is set to 500.

[0129] The ratios of elite count, crossover, and mutation are assigned to 30%, 50%, and 20%, respectively. If neither of these conditions is satisfied, 2 elite counts, 5 crossovers, and 2 mutations are created, and the series of processes is repeated.

[0130] If the allowable change in the objective function between generations becomes 0.0001 or less, or if 500 generations have passed, the entity that minimizes the objective function is determined by the mass and friction of the transport system model.

[0131] For the Y-axis and Z-axis as well, select the transport system models corresponding to Figures 9 and 10 and repeat the above process to determine the mass and frictional force of each transport system model.

[0132] The determined mass and frictional force are applied to each model to construct a digital twin of each axis.

[0133] Thus, the digital twin construction and evaluation system for a machine tool according to the present invention derives a transient region for a selected feed system and utilizes only the data of the transient region reflecting dynamic characteristics to reduce the time and cost of constructing the digital twin, and since existing programs can be used to reflect dynamic characteristics, compatibility is increased and the occurrence of errors is minimized, thereby promoting convenience for the operator.

[0134] As illustrated in FIGS. 1 to 2 and FIGS. 7, the digital twin evaluation unit (300) of the digital twin construction and evaluation system (1) of the machine tool according to the present invention includes a storage module (310), a judgment unit (320), an error value calculation unit (330), an evaluation unit (340) for each selected feed system, a verification unit (350), a correction unit (360), a correction value calculation unit (370), and an evaluation unit (380) for each actual specific shape processing.

[0135] The storage module (310) stores one or more of the data for a reference error value, reference shape information, tool information, and machining surface information for a workpiece to be machined, or reference correction value for evaluating the constructed digital twin. Preferably, the storage module stores all of the data for a reference error value, reference shape information, tool information, and machining surface information for a workpiece to be machined, and reference correction value for evaluating the constructed digital twin. Additionally, the storage module may be various storage devices such as ROM, RAM, EPROM, flash drive, hard drive, etc., and may be web storage that performs the storage function of a memory unit on the internet.

[0136] The judgment unit (320) determines whether to evaluate by selected transfer system or by actual specific shape processing.

[0137] The error value calculation unit (330) calculates a digital twin error value (E1) resulting from the error between the input value (Xref) applied to the digital twin and the output value (X) resulting from the operation of the digital twin when evaluated by the judgment result of the judgment unit, and an actual machine tool error value (E2) resulting from the error between the input value (Xref) applied to the actual machine tool and the output value (X') resulting from the operation of the actual machine tool.

[0138] The evaluation unit (340) for each selected transfer system evaluates the digital twin for each selected transfer system by comparing and analyzing the difference (E1-E2) between the digital twin error value (E1) and the actual machine tool error value (E2) based on the calculation result of the error value calculation unit with the reference error value stored in the storage module.

[0139] In other words, the evaluation unit for each selected feed system evaluates the similarity between the digital twin and the actual machine tool for each axis of the selected feed system.

[0140] Specifically, as shown in Fig. 13, for each feed speed of the evaluation unit for each selected feed system, F300 for 300 mm / min, F600 for 600 mm / min, F900 for 900 mm / min, and F1200 for 1200 mm / min, the expected error amount of the vertical axis according to time on the horizontal axis does not exceed 5 micrometers (㎛) based on the digital twin, and thus the error of the digital twin constructed for the actual machine tool and the selected feed system behaves similarly with less than 5 micrometers (㎛), thereby improving accuracy and reliability.

[0141] The verification unit (350) verifies the reference shape information and tool information or processing surface information according to the actual specific shape to be processed when evaluating the actual specific shape processing results of the judgment unit.

[0142] The modification unit (360) modifies the input value (Xref) applied to the digital twin constructed according to the verification result of the verification unit and the data stored in the storage module, and the input value (Xref) applied to the actual machine tool by reflecting the reference shape information, tool information, and machining surface information.

[0143] The correction value calculation unit (370) calculates a digital twin correction value (K1) based on the error between the correction input value (X'ref) applied to the digital twin built according to the correction result of the correction unit and the data stored in the storage module and the output value (X'') based on the operation of the digital twin built, and an actual machine tool correction value (K2) based on the error between the correction input value (X'ref) applied to the actual machine tool and the output value (X''') based on the operation of the actual machine tool.

[0144] The evaluation unit (380) for each actual specific shape machining evaluates the digital twin by comparing and analyzing the difference (K1-K2) between the digital twin correction value (K1) and the actual machine tool correction value (K2) based on the calculation result of the correction value calculation unit with the reference correction value and reference shape information stored in the storage module.

[0145] In other words, unlike the evaluation unit for selected feed systems, the evaluation unit for specific shape machining evaluates the similarity between the digital twin and the actual machine tool during actual specific shape machining for the selected feed system.

[0146] Specifically, the evaluation unit for actual specific shape machining modifies and reflects input values ​​through the reference shape information based on the reference CAD shape information and STL information for actual specific shape machining.

[0147] In addition, since the tool information may vary during actual machining of a specific shape, the evaluation unit for each specific shape reflects the geometric structure of the tool during actual machining and distinguishes STL fragments affected by the position of the ball end mill to modify and reflect the input values.

[0148] Furthermore, since the processing surface information may change during actual specific shape processing, the evaluation unit for each actual specific shape processing distinguishes between the processed and non-processed surfaces during actual specific shape processing and modifies and reflects the input values.

[0149] Specifically, when the information regarding the actual processing of a specific shape is reflected through the evaluation unit for the actual processing of a specific shape, there is almost no difference between the graph of the shape and error range during actual processing of a specific shape using the actual machine tool shown in Fig. 14a and the graph of the shape and error range during actual processing of a specific shape using the digital twin constructed for the selected feed system shown in Fig. 14b, so it can be seen that the accuracy and similarity between the digital twin and the actual machine tool are almost identical.

[0150] In addition, if information regarding actual specific shape processing is reflected through the evaluation unit for actual specific shape processing, as shown in Fig. 15, it can be seen that the contour error of the digital twin over time (red dotted line) and the contour error of the actual machine tool over time (blue solid line) are almost identical.

[0151] A method for constructing and evaluating a digital twin of a machine tool according to the present invention will be described with reference to FIG. 16 to 18. As shown in FIG. 16, the method for constructing and evaluating a digital twin of a machine tool according to the present invention includes a data storage step (S100), a digital twin construction step (S200), and a digital twin evaluation step (S300).

[0152] In each step, the specific operation process, operating principle, configuration, and content of the device are identical to the digital twin construction and evaluation system for machine tools described in the specification of the present invention. Therefore, the following description will focus on the specific features of the digital twin construction and evaluation method for machine tools with reference to FIGS. 16 to 18.

[0153] It constructs a digital twin and stores data to evaluate the constructed digital twin.

[0154] After the data storage step (S100), a machine tool having one or more feed systems and processing a workpiece is selected, a transient region for the selected feed system is derived, and a digital twin is constructed using only the data of the transient region that reflects dynamic characteristics.

[0155] After the digital twin construction phase (S200), the constructed digital twin is evaluated.

[0156] As illustrated in FIG. 17, the digital twin construction step (S200) of the method for constructing and evaluating a digital twin of a machine tool according to the present invention includes a selection step (S201), a determination step (S202), a generation step (S203), a calculation step (S204), an acquisition step (S205), an operation step (S206), a calculation step (S207), a comparison step (S208), a derivation step (S209), an identification step (S210), and a construction step (S211).

[0157] Select one or more feed systems from the feed systems of the machine tool.

[0158] After the selection step (S201), the transfer speed of the selected transfer system is determined based on the selection result and the previously stored data.

[0159] After the decision step (S202), reference input information is generated based on the decision result and the previously stored data.

[0160] After the generation step (S203), the rate of change in position is calculated based on the generation result and the previously stored data.

[0161] After the calculation step (S204), position feedback information is obtained by actually driving the machine tool for the feed system selected in the selection step using the reference input information based on the generation result.

[0162] After the acquisition step (S205), the position feedback change rate is calculated based on the acquisition result and the previously stored data.

[0163] After the calculation step (S206), the error values ​​of the position change rate and the position feedback change rate are calculated based on the calculation result.

[0164] After the calculation step (S207), the calculated error value is compared with the previously stored reference error value.

[0165] After the comparison step (S208), the period from the point where the error value deviates from the reference error value according to the comparison result to the point where the reference error value is satisfied is derived as the transient region.

[0166] After the derivation step (S209), dynamic characteristic parameters of the selected transport system are identified through reference input information and position feedback information corresponding to the derived transient region.

[0167] After the identification step (S210), a digital twin for the selected transport system is constructed using transient region information to which dynamic characteristic parameters based on the identification result are applied.

[0168] As illustrated in FIG. 17, the digital twin evaluation step (S300) of the method for constructing and evaluating a digital twin of a machine tool according to the present invention includes a judgment step (S301), an error value calculation step (S302), an evaluation step for each selected feed system (S303), a verification step (S304), a correction step (S305), a correction value calculation step (S306), and an evaluation step for each actual specific shape machining (S307).

[0169] Determine whether to evaluate based on the selected transfer system or based on the actual specific shape machining.

[0170] After the judgment step (S301), when evaluating each feed system selected as a result of the judgment, a digital twin error value is calculated based on the error between the input value applied to the constructed digital twin and the output value resulting from the operation of the constructed digital twin, and an actual machine tool error value is calculated based on the error between the input value applied to the actual machine tool and the output value resulting from the operation of the actual machine tool.

[0171] After the error value calculation step (S302), the difference between the digital twin error value and the actual machine tool error value based on the error value calculation result is compared and analyzed with a stored reference error value to evaluate the digital twin for each selected feed system.

[0172] After the judgment step (S301), when evaluating the actual specific shape machining results, the reference shape information and tool information or machining surface information according to the actual specific shape to be machined are verified.

[0173] After the verification step (S304), the input values ​​applied to the digital twin constructed according to the verification results and pre-stored data, and the input values ​​applied to the actual machine tool are modified by reflecting the reference shape information, tool information, and machining surface information.

[0174] After the modification step (S305), a digital twin correction value is calculated based on the error between the modified input value applied to the digital twin and the output value resulting from the operation of the digital twin, according to the modification result and the previously stored data, and an actual machine tool correction value is calculated based on the error between the modified input value applied to the actual machine tool and the output value resulting from the operation of the actual machine tool.

[0175] After the correction value calculation step (S306), the difference between the digital twin correction value and the actual machine tool correction value based on the correction value calculation result is compared and analyzed with the stored reference correction value and reference shape information to evaluate the digital twin for each actual specific shape machining.

[0176] Thus, the method for constructing and evaluating a digital twin of a machine tool according to the present invention reduces the time and cost of constructing the digital twin and improves the convenience of the operator by deriving a transient region for a selected feed system and constructing the digital twin using only the data of the transient region that reflects dynamic characteristics. Furthermore, after constructing the digital twin for a selected feed system, the digital twin constructed for each selected feed system or the digital twin constructed for each actual specific shape machining can be evaluated, thereby maximizing the accuracy and similarity of the constructed digital twin, improving stability and reliability, and preventing resource waste.

[0177] Furthermore, the embodiments according to the present invention described above may be implemented in the form of program instructions that can be executed through various computer components and recorded on a computer-readable recording medium. The computer-readable recording medium may include program instructions, data files, data structures, etc., either individually or in combination. The program instructions recorded on the computer-readable recording medium may be those specifically designed and configured for the present invention or those known and available to those skilled in the art of computer software. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tapes; optical recording media such as CD-ROMs and DVDs; magneto-optical media such as floptical disks; and hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, and flash memory. Examples of program instructions include machine code, such as that generated by a compiler, as well as high-level language code that can be executed by a computer using an interpreter, etc. Hardware devices may be modified into one or more software modules to perform processing according to the present invention, and vice versa.

[0178] The specific embodiments described in this invention are examples and do not limit the scope of the invention in any way. For the sake of brevity of the specification, descriptions of prior electronic configurations, control systems, software, and other functional aspects of said systems may be omitted. Additionally, the connections of lines or connecting members between components shown in the drawings are illustrative of functional connections and / or physical or circuit connections, and may be replaced or additionally represented as various functional connections, physical connections, or circuit connections in actual devices. Furthermore, unless specifically stated as “essential,” “importantly,” etc., a component may not be strictly necessary for the application of the invention.

[0179] Furthermore, although the detailed description of the present invention has been explained with reference to preferred embodiments of the invention, those skilled in the art or those with ordinary knowledge in the relevant technical field will understand that various modifications and changes can be made to the invention without departing from the spirit and technical scope of the invention as set forth in the claims below. Accordingly, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be determined by the claims.

[0180] <Explanation of Symbols>

[0181] 1: Digital Twin Construction and Evaluation System for Machine Tools

[0182] 100 : Machine tools

[0183] 200 : Digital Twin Construction Unit

[0184] 300: Digital Twin Evaluation Unit

Claims

1. A machine tool for processing a workpiece equipped with one or more feed systems; and A digital twin construction unit that is connected to the machine tool via a network and constructs a digital twin for a selected feed system among the feed systems of the machine tool; A digital twin construction and evaluation system for a machine tool, characterized in that the above-described digital twin construction unit derives a transient region for a selected transfer system and constructs a digital twin by utilizing only the data of the transient region reflecting dynamic characteristics.

2. In Paragraph 1, A digital twin construction and evaluation system for a machine tool, further comprising: a digital twin evaluation unit that is networked with the machine tool and the digital twin construction unit and evaluates the digital twin constructed through the digital twin construction unit.

3. In Paragraph 2, A digital twin construction and evaluation system for a machine tool, characterized in that the digital twin evaluation unit examines the difference in error values ​​for each feed system between the digital twin constructed for each feed system selected by the digital twin construction unit and the actual machine tool, and evaluates each selected feed system.

4. In Paragraph 3, A digital twin construction and evaluation system for a machine tool, characterized by the above-mentioned digital twin evaluation unit reflecting reference shape information and tool information or machining surface information for a specific shape to be actually machined during actual specific shape machining, analyzing the reference shape information and correction values ​​of the actual machine tool and the digital twin constructed through the above-mentioned digital twin construction unit, and evaluating each actual specific shape machining.

5. In Paragraph 2, The above digital twin construction unit is, A database unit that stores one or more data among data regarding feed system information, feed speed information, reference error value, processing program, or driving program to construct a digital twin for a selected feed system; A selection unit for selecting one or more feed systems among the feed systems of the machine tool through data stored in the database unit; A determination unit that determines the transfer speed of the selected transfer system according to the selection result of the above selection unit and the data stored in the above database unit; A generating unit that generates reference input information according to the decision result of the above-mentioned decision unit and the data stored in the above-mentioned database unit; A calculation unit that calculates the rate of change in position according to the generation result of the above-mentioned generation unit and the data stored in the above-mentioned database unit; An acquisition unit that acquires position feedback information by actually driving the machine tool for the transfer system selected in the selection unit using reference input information based on the generation result of the generation unit; A calculation unit that calculates the position feedback change rate according to the acquisition result of the above acquisition unit and the data stored in the above database unit; A calculation unit that calculates the error values ​​of the position change rate and the position feedback change rate according to the calculation result of the calculation unit and the calculation result of the operation unit; A comparison unit that compares an error value based on the calculation result of the above-mentioned calculation unit with a reference error value stored in the above-mentioned database unit; A derivation unit that derives the period from the point where the error value deviates from the reference error value to the point where it satisfies the reference error value as an excess region according to the comparison result of the above comparison unit; An identification unit that identifies dynamic characteristic parameters of a selected transport system through reference input information and position feedback information corresponding to the transient region derived according to the derivation result of the above derivation unit; and A digital twin construction and evaluation system for a machine tool, characterized by including: a construction unit that constructs a digital twin for a selected transfer system by utilizing transient region information to which dynamic characteristic parameters are applied according to the identification result of the identification unit.

6. In Paragraph 5, A digital twin construction and evaluation system for a machine tool, characterized in that the above-mentioned determination unit determines the feed speed of a selected feed system as an equal value or a representative value within a feed speed range.

7. In Paragraph 5, A digital twin construction and evaluation system for a machine tool, characterized in that the above-mentioned generation unit is generated through slope input using position input information over time.

8. In Paragraph 5, A digital twin construction and evaluation system for a machine tool, characterized in that the identification unit identifies and selects dynamic characteristic parameters through a genetic algorithm for each transfer system selected through the selection unit.

9. In Paragraph 4, The above digital twin evaluation unit is, A storage module that stores one or more data among reference error values, reference shape information, tool information, and machining surface information for a workpiece to be actually machined, or data regarding reference correction values ​​to evaluate a constructed digital twin; A judgment unit that determines whether to evaluate based on selected transfer systems or based on actual specific shape machining; An error value calculation unit that calculates a digital twin error value resulting from the error between the input value applied to the constructed digital twin and the output value resulting from the operation of the constructed digital twin when evaluating each selected transfer system based on the judgment result of the above judgment unit, and an actual machine tool error value resulting from the error between the input value applied to the actual machine tool and the output value resulting from the operation of the actual machine tool; and A digital twin construction and evaluation system for a machine tool, characterized by including: an evaluation unit for each selected feed system that evaluates the digital twin for each selected feed system by comparing and analyzing the difference between the digital twin error value and the actual machine tool error value according to the calculation result of the error value calculation unit with the reference error value stored in the storage module.

10. In Paragraph 9, The above digital twin evaluation unit is, A verification unit that verifies reference shape information and tool information or machining surface information according to the actual specific shape to be machined when evaluating the actual specific shape machining results of the above-mentioned judgment unit; A modification unit that modifies the input values ​​applied to the digital twin and the input values ​​applied to the actual machine tool based on the verification result of the verification unit and the data stored in the storage module, by reflecting reference shape information, tool information, and machining surface information; A correction value calculation unit that calculates a digital twin correction value based on the error between the modified input value applied to the digital twin and the output value resulting from the operation of the digital twin according to the modification result of the above modification unit and the data stored in the above storage module, and an actual machine tool correction value based on the error between the modified input value applied to the actual machine tool and the output value resulting from the operation of the actual machine tool; and A digital twin construction and evaluation system for a machine tool, further comprising: an evaluation unit for actual specific shape machining that evaluates the digital twin for each actual specific shape machining by comparing and analyzing the difference between the digital twin correction value and the actual machine tool correction value according to the calculation result of the correction value calculation unit with the reference correction value and reference shape information stored in the storage module.

11. A step of constructing a digital twin and storing data for evaluating the constructed digital twin; A step of deriving a transient region for a selected feed system among the feed systems of a machine tool that processes a workpiece and is equipped with one or more feed systems, and constructing a digital twin by utilizing only the data of the transient region reflecting dynamic characteristics; and A method for constructing and evaluating a digital twin of a machine tool, comprising the step of evaluating the constructed digital twin.

12. In Paragraph 11, The step of constructing the above digital twin is, A step of selecting one or more feed systems from the feed systems of the machine tool above; A step of determining the transfer speed of the selected transfer system based on the selection result and previously stored data; A step of generating reference input information based on the decision result and previously stored data; A step of calculating the rate of change in position based on the generated result and pre-stored data; A step of actually driving the machine tool for the feed system selected in the selection step using standard input information based on the generation result to obtain position feedback information; A step of calculating the position feedback change rate based on the acquired result and previously stored data; A step of calculating the error value of the position change rate and the position feedback change rate according to the calculation result and the operation result; A step of comparing the calculated error value with a previously stored reference error value; A step of deriving the transient region from the point where the error value deviates from the reference error value to the point where it satisfies the reference error value based on the comparison result; A step of identifying dynamic characteristic parameters of a selected transport system through reference input information and position feedback information corresponding to the derived transient region; and A method for constructing and evaluating a digital twin of a machine tool, characterized by including the step of constructing a digital twin for a selected transfer system using transient region information to which dynamic characteristic parameters are applied according to the identification result.

13. In Paragraph 12, The step of evaluating the digital twin constructed above is, A step of determining whether to evaluate based on selected transfer systems or based on actual specific shape machining; A step of calculating a digital twin error value resulting from the error between the input value applied to the constructed digital twin and the output value resulting from the operation of the constructed digital twin when evaluating each selected feed system based on the judgment result, and an actual machine tool error value resulting from the error between the input value applied to the actual machine tool and the output value resulting from the operation of the actual machine tool; and A method for constructing and evaluating a digital twin of a machine tool, characterized by including the step of evaluating the digital twin for each selected feed system by comparing and analyzing the difference between the digital twin error value and the actual machine tool error value based on the error value calculation result with a stored reference error value.

14. In Paragraph 13, The step of evaluating the digital twin constructed above is, After the above judgment step, when evaluating the actual specific shape machining results, a step of verifying reference shape information and tool information or machining surface information according to the actual specific shape to be machined; A step of modifying the input values ​​applied to the digital twin constructed based on verification results and pre-stored data, and the input values ​​applied to the actual machine tool, by reflecting reference shape information, tool information, and machining surface information; A step of calculating a digital twin correction value based on the error between the modified input value applied to the digital twin constructed according to the modification result and the output value resulting from the operation of the constructed digital twin, and an actual machine tool correction value based on the error between the modified input value applied to the actual machine tool and the output value resulting from the operation of the actual machine tool; and A method for constructing and evaluating a digital twin of a machine tool, characterized by including the step of evaluating the digital twin for each actual specific shape machining by comparing and analyzing the difference between the digital twin correction value and the actual machine tool correction value based on the calculation result of the correction value with a stored reference correction value and reference shape information.

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