Measurement device and measurement method therefor

Abstract

The invention provides a measuring device and a measuring method of the measuring device. The measuring device and the measuring method of the measuring device can acquire a measured value of a length measuring instrument under more appropriate conditions than before. The present invention is provided with: a first measurement control unit (repeated measurement control unit) that repeatedly acquires a measurement value of a length meter after the start of movement of either the length meter (laser length meter) or a measurement target (corner prism) toward a measurement point; an index calculation unit (standard deviation calculation unit) that repeatedly calculates an index indicating the deviation of the measured value; a standstill start time determination unit that determines, as a standstill start time (ST), a time during which the index is equal to or less than a threshold value; a movement speed calculation unit that repeats the calculation of one movement speed; a waiting time determination unit that determines a waiting time (WT) from the rest start time (ST) on the basis of one movement speed information; and a second measurement control unit (post-movement measurement control unit) that executes the formal measurement when the waiting time (WT) has elapsed from the rest start time (ST).

Description

Technical Field

[0001] The present invention relates to a measuring device and a measuring method for the measuring device. The measuring device includes a length measuring device, and when either the length measuring device or a measurement object thereof moves to a measuring point, a measurement value of the length measuring device is obtained. Background Art

[0002] Patent document 1 discloses a measuring device for measuring the movement accuracy (movement error and backlash) of a stage of an NC (numerically controlled) machine tool. The measuring device includes a laser length measuring device. The laser length measuring device emits measurement light toward a corner cube prism disposed on the stage, receives reflected light of the measurement light reflected by the corner cube prism, and obtains a measured value of the distance to the corner cube prism based on a light receiving signal of the reflected light.

[0003] When measuring the movement accuracy of the stage, when the NC controller instructs the moving mechanism of the stage to move the stage (corner cube) only by the target movement amount to the measurement point (measurement position), the actual movement amount of the stage is calculated based on the measurement values ​​obtained by the laser length measuring device before the stage moves and after the stage stops moving. Thus, by comparing the above-mentioned target movement amount with the actual movement amount of the stage, the movement accuracy of the stage can be obtained. At this time, if an external signal is used to determine the timing of obtaining the measurement value of the laser length measuring device after the stage stops moving, it is possible to perform the acquisition of the measurement value of the laser length measuring device during the reverberation vibration of the stage. In addition, when the measurement value of the laser length measuring device before and after the stage moves is obtained at a fixed time interval, the laser length measuring device may obtain the measurement value regardless of the movement / stationary state of the stage.

[0004] Therefore, in the measuring device described in Patent Document 1, the acquisition of the measured value of the laser length measuring device is repeatedly performed before the stage (corner cube) moves to the measuring point, and the stage is judged to have completed the movement to the measuring point (stationary at the measuring point) based on the change state of the measured value of the laser length measuring device. Specifically, the chi-square test of the moving speed of the stage is performed based on the measured values ​​repeatedly acquired by the laser length measuring device, and it is judged whether the stage is stationary at the measuring point based on whether the conditions preset by the operator (user) are satisfied. As a result, in the measuring device described in Patent Document 1, the acquisition of the measured value of the laser length measuring device (formal measurement) can be automatically performed when the stage is stationary at the measuring point.

[0005] Prior Art Literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 10-225844 Summary of the invention

[0008] -Problems to be solved by the invention-

[0009] However, in the measuring device described in Patent Document 1, when the conditions set by the operator are satisfied, it is determined that the stage (corner cube) is stationary at the measuring point, and the formal measurement of the laser length measuring device is automatically performed. At this time, if the conditions (threshold values) set by the operator are inappropriate, the laser length measuring device may obtain a measurement value containing a deviation that the operator does not want (for example, a measurement value in reverberation vibration). In addition, depending on the setting of the conditions, the time until the start of the formal measurement of the laser length measuring device is unnecessarily delayed, and the measurement time may become long.

[0010] The present invention has been made in view of such circumstances, and an object of the present invention is to provide a measuring device and a measuring method for the measuring device that can obtain a measurement value of a length measuring device under more appropriate conditions than before.

[0011] A measuring device for achieving the purpose of the present invention comprises a length measuring device for obtaining a measurement value of a distance to a measuring object, and when either the length measuring device or the measuring object moves to a predetermined measuring point, the measurement value of the length measuring device is obtained, and the measuring device comprises: a first measuring control unit for repeatedly obtaining the measurement value of the length measuring device after starting movement to the measuring point in one direction; an index calculation unit for repeatedly calculating an index representing a deviation of the measurement value based on the measurement value repeatedly obtained by the length measuring device; and a stationary start time determination unit for determining a time when the index calculated by the index calculation unit becomes less than a predetermined threshold value as a time when one party is in the measuring state. a moving speed calculation unit that repeatedly performs calculations of the moving speed of one side based on the measurement values ​​repeatedly obtained by the length measuring device and the intervals between the measurement values; a waiting time determination unit that determines the waiting time from the stillness start time determined by the stillness start time determination unit to the time when the length measuring device starts formal measurement of the measurement value at the measuring point based on the moving speed information of one side obtained from the calculation result of the moving speed calculation unit; and a second measurement control unit that performs formal measurement based on the length measuring device when the waiting time determined by the waiting time determination unit has passed since the stillness start time determined by the stillness start time determination unit.

[0012] According to this measuring device, it is possible to automatically determine an appropriate waiting time according to the moving speed information.

[0013] In the measuring device according to another embodiment of the present invention, the moving speed information includes at least one of the maximum value of the moving speed and the time variation of the moving speed during the deceleration of the moving speed. Thus, an appropriate waiting time corresponding to at least one of the maximum value of the moving speed and the time variation during the deceleration can be automatically determined.

[0014] In the measuring device according to another aspect of the present invention, the index calculation unit performs calculation of the index based on a plurality of measurement values ​​obtained by the length measuring device within the fixed time interval at predetermined fixed time intervals. This makes it possible to determine whether one side is in a stationary state.

[0015] In the measurement device according to another aspect of the present invention, the index calculation unit calculates the standard deviation of the measurement value as the index. This makes it possible to determine whether one side is in a stationary state.

[0016] In the measurement device according to another aspect of the present invention, the waiting time determination unit determines the waiting time using a learned model that takes the moving speed information as input and outputs the waiting time. This makes it possible to automatically determine an appropriate waiting time according to the moving speed information.

[0017] A measurement device according to another aspect of the present invention includes a movement control unit that drives a movement mechanism that moves the one side to move the one side to a measurement point.

[0018] A measuring method for a measuring device for achieving the purpose of the present invention, the measuring device having a length measuring device for obtaining a measurement value of a distance to a measuring object, wherein when either the length measuring device or the measuring object moves to a predetermined measuring point, the measurement value of the length measuring device is obtained, and the measuring method for the measuring device comprises the following steps: a first measurement control step of repeatedly obtaining the measurement value of the length measuring device after starting movement to the measuring point in one direction; an index calculation step of repeatedly calculating an index indicating a deviation of the measurement value based on the measurement value repeatedly obtained by the length measuring device; and a still start time determination step of setting the time for an index calculated in the index calculation to be below a predetermined threshold value. A stillness start time is determined for one party to be still at a measuring point; a moving speed calculation step, which repeatedly performs calculations of the moving speed of one party based on measurement values ​​repeatedly obtained by the length measuring device and the intervals between the measurement values; a waiting time determination step, which determines the waiting time from the stillness start time determined in the stillness start time determination step to the time when the length measuring device starts formal measurement of the measurement value at the measuring point based on the moving speed information of one party obtained from the calculation result of the moving speed calculation step; and a second measurement control step, which performs formal measurement of the length measuring device when the waiting time determined in the waiting time determination step has passed since the stillness start time determined in the stillness start time determination step.

[0019] -Effects of the Invention-

[0020] The present invention can obtain the measurement value using the length measuring device under more appropriate conditions than before. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1This is a schematic diagram of an NC machine tool and a measuring device of the present invention used for measuring the accuracy of the NC machine tool.

[0022] Figure 2 It is a functional block diagram of the control device.

[0023] Figure 3 3B is a graph showing a first movement example and a second movement example (see reference numeral 3B) of the stage in the X direction when the stage movement accuracy is measured.

[0024] Figure 4 This is a graph showing the temporal change of the standard deviation repeatedly calculated by the standard deviation calculation unit during repeated measurements of the laser length measuring device.

[0025] Figure 5 This is a graph showing the temporal change in the moving speed of the stage repeatedly calculated by the moving speed calculation unit during repeated measurements by the laser length measuring device.

[0026] Figure 6 This is a graph for explaining the waiting time determined by the waiting time determination unit.

[0027] Figure 7 This is an explanatory diagram showing an example of teaching data used in machine learning of a learned model.

[0028] Figure 8 This is an explanatory diagram for explaining an example of determination of the waiting time using the learned model by the waiting time determination unit.

[0029] Fig. 9 This is a flowchart showing the flow of a measurement process of the movement accuracy of a stage of an NC machine tool performed by a measurement device.

[0030] -Description of Reference Numerals-

[0031] 10…NC machine tool, 11…processing tool holding unit, 12…holding unit moving mechanism, 13…stage, 14…stage moving mechanism, 15…NC controller, 18…corner cube, 20…measuring device, 21…laser length measuring device, 22…laser light source, 24…laser interference unit, 26…signal processing unit, 28A…optical fiber cable, 28B…optical fiber cable, 30…control device, 31…pre-movement measurement control unit, 32…movement control unit, 32A…NC program , 33…repeated measurement control unit, 34…standard deviation calculation unit, 35…stationary start time determination unit, 36…moving speed calculation unit, 37…time determination unit, 37a…learning completion model, 38…post-movement measurement control unit, 39…measurement value storage unit, 50…moving speed information, 52…teaching data, L1…measurement light, L2…reflected light, L3…interference light, P1…maximum value, P2…time change, Q…start timing, ST…stationary start time, Th…threshold value. DETAILED DESCRIPTION

[0032] [Structure of NC machine tools]

[0033] Figure 1 The diagram schematically shows an NC machine tool 10 and a measuring device 20 of the present invention for measuring the accuracy of the NC machine tool 10. In the diagram, of the mutually orthogonal XYZ directions, the XY direction is parallel to the horizontal direction, and the Z direction is parallel to the vertical direction.

[0034] like Figure 1 As shown, the NC machine tool 10 is a machining center capable of continuously performing various machining operations such as boring, milling, drilling, tapping, and reamer finishing. The NC machine tool 10 includes a machining tool holder 11 , a holder moving mechanism 12 , a stage 13 , a stage moving mechanism 14 , and an NC controller 15 .

[0035] The processing tool holding part 11 holds and drives various processing tools for processing a workpiece (not shown). The holding part moving mechanism 12 is a well-known actuator that holds the processing tool holding part 11 so as to be movable in the Z direction (vertical direction).

[0036] When processing a workpiece (not shown), the workpiece is placed on the stage 13. In addition, a corner cube 18 is placed on the stage 13 when measuring the movement accuracy of the stage 13, etc., which will be described later. The corner cube 18 moves integrally with the stage 13, and therefore corresponds to the measurement object of the present invention together with the stage 13. In addition, other reflectors may be placed on the stage 13 instead of the corner cube 18. The stage moving mechanism 14 is a well-known actuator that holds the stage 13 so that it can move freely in the XY directions.

[0037] The NC controller 15 controls the driving of the processing tool by the processing tool holding unit 11 , the movement of the processing tool holding unit 11 by the holding unit moving mechanism 12 , the movement of the stage 13 by the stage moving mechanism 14 , and the like.

[0038] [Structure of measuring device]

[0039] The measuring device 20 measures the movement accuracy (movement error and backlash) of the stage 13 in accordance with the provisions of the movement error and backlash of ISO230-2 or JIS-B-6201 (see the above-mentioned Patent Document 1). Specifically, the measuring device 20 measures the actual movement amount of the corner cube 18 mounted on the stage 13, that is, the actual movement amount of the stage 13, when the NC controller 15 instructs the stage moving mechanism 14 to move the stage 13 only by the target movement amount to a given measurement point.

[0040] In addition, the measuring device 20 can also measure the moving accuracy of the processing tool holding part 11, that is, the actual moving amount of the processing tool holding part 11 when the NC controller 15 instructs the holding part moving mechanism 12 to move the processing tool holding part 11 only by the target moving amount to a given measuring point. In addition, in this specification, the measurement of the moving accuracy of the stage 13 by the measuring device 20 is described as an example.

[0041] The measuring device 20 includes a laser length measuring device 21 and a control device 30. The laser length measuring device 21 corresponds to the length measuring device of the present invention, and includes a laser light source 22, a laser interference unit 24, a signal processing unit 26, and optical fiber cables 28A and 28B. The laser light source 22 and the laser interference unit 24 are connected via an optical fiber cable 28A, and the laser interference unit 24 and the signal processing unit 26 are connected via an optical fiber cable 28B.

[0042] The laser light source 22 emits laser measurement light L1 to the laser interference unit 24 via the optical fiber cable 28A.

[0043] The laser interference unit 24 (also referred to as a sensor head) is detachably held on the processing tool holding portion 11, and emits the measurement light L1 incident from the laser light source 22 via the optical fiber cable 28A toward the corner cube 18 on the stage 13 in the X direction. As a result, the reflected light L2 of the measurement light L1 reflected by the corner cube 18 is incident on the laser interference unit 24. Then, the laser interference unit 24 generates interference light L3 of the reflected light L2 and a part of the measurement light L1 reflected by a reference surface (not shown) (reference light), and emits the interference light L3 to the signal processing unit 26 via the optical fiber cable 28B.

[0044] The signal processing unit 26 receives the interference light L3 incident from the laser interference unit 24 via the optical fiber cable 28B. Then, the signal processing unit 26 calculates the measured value (hereinafter referred to as the measured value) of the distance between the laser interference unit 24 and the corner cube prism 18 by a known method based on the light receiving signal of the received interference light L3, and outputs the calculation result of the measured value to the control device 30.

[0045] Under the control of the control device 30 described later, the laser length measuring device 21 performs formal measurement to obtain the measured value before the stage 13 (corner cube prism 18) of the stage moving mechanism 14 moves and after the stage 13 of the stage moving mechanism 14 moves (in a stationary state) under the control of the control device 30 described later. Hereinafter, the formal measurement before the movement of the stage 13 is referred to as the formal measurement before movement, and the formal measurement after the movement of the stage 13 is referred to as the formal measurement after movement.

[0046] Furthermore, the laser length measuring device 21 performs repeated measurement (also referred to as continuous measurement) in which the measurement value is repeatedly acquired during the period from when the stage moving mechanism 14 starts the movement of the stage 13 (corner cube 18) to when the stage 13 stops under the control of the control device 30. Here, the measurement value repeatedly acquired by the laser length measuring device 21 is used in the determination process of the control device 30 to determine whether the stage 13 stops and the determination process of the timing of performing the actual measurement after the movement of the stage 13 is completed.

[0047] The control device 30 has a computing circuit composed of various processors and memories. The various processors include CPU (Central Processing Unit), GPU (Graphics Processing Unit), ASIC (Application Specific Integrated Circuit), and programmable logic devices [such as SPLD (Simple Programmable Logic Devices), CPLD (Complex Programmable Logic Device) and FPGA (Field Programmable Gate Arrays)]. In addition, the various functions of the control device 30 can be implemented by one processor or by multiple processors of the same or different types.

[0048] The control device 30 is connected to the NC controller 15, the laser light source 22, and the signal processing unit 26 via a signal cable (not shown). When measuring the movement accuracy of the stage 13, the control device 30 controls the operation of the NC controller 15 and the laser length measuring device 21 (laser light source 22, signal processing unit 26), thereby controlling the movement of the stage 13 of the stage moving mechanism 14 and the acquisition of the measurement value of the laser length measuring device 21.

[0049] Figure 2 is a functional block diagram of the control device 30. Figure 2 As shown, the control device 30 functions as a pre-movement measurement control unit 31, a movement control unit 32, a repeated measurement control unit 33, a standard deviation calculation unit 34, a stationary start time determination unit 35, a movement speed calculation unit 36, a waiting time determination unit 37, a post-movement measurement control unit 38 and a measurement value storage unit 39 by executing a program read from a memory not shown in the figure.

[0050] The pre-movement measurement control unit 31 controls the laser length measuring device 21 to perform the pre-movement formal measurement when, for example, an operation for starting the measurement of the movement accuracy of the stage 13 is input to the operation unit (not shown) of the control device 30. Thus, before the stage 13 (corner cube 18) starts to move, the measurement value for measuring the movement accuracy of the stage 13 is obtained by the laser length measuring device 21.

[0051] For example, when the formal measurement is completed before the stage 13 is moved, the movement control unit 32 generates an NC program 32a for moving the stage 13 in the X direction by a movement amount corresponding to the test method specified in ISO230-2 or JIS-B-6201, etc. to the measurement points separated in the X direction (or the Y direction). Then, the movement control unit 32 outputs the NC program 32a to the NC controller 15.

[0052] Figure 3 3A and 3B are graphs showing a first movement example (see reference numeral 3A) and a second movement example (see reference numeral 3B) of the stage 13 in the X direction when the movement accuracy of the stage 13 is measured. In addition, the horizontal axis of each graph is time (msec) and the vertical axis is the displacement amount (mm) of the stage 13 in the X direction. Figure 3 As shown, the NC controller 15 drives the stage moving mechanism 14 according to the NC program 32 a to move the stage 13 (corner cube 18 ) in the X direction toward a measurement point, and stops the stage 13 at the measurement point.

[0053] Alternatively, the operator may directly input an instruction to move the stage 13 in the X direction (or the Y direction) by the above-mentioned movement amount to the NC controller 15. In this case, the movement control unit 32 can be omitted.

[0054] return Figure 2 The repeated measurement control unit 33 is equivalent to the first measurement control unit of the present invention. The repeated measurement control unit 33 performs repeated measurement by the laser length meter 21 after the stage moving mechanism 14 starts the movement of the stage 13 (corner cube prism 18). Thus, at least during the movement of the stage 13, the laser length meter 21 repeatedly performs the acquisition of the measured value of the distance to the corner cube prism 18. The repeated measurement by the laser length meter 21 is performed, for example, until the movement of the stage 13 by the stage moving mechanism 14 stops, or until the stationary start time determination unit 35 described later determines the stationary start time ST (refer to Figure 6 ) for the period ending in .

[0055] The acquisition interval of the measurement value of the laser length measuring device 21 during the repeated measurement is used for the calculation of the moving speed of the stage 13 by the moving speed calculation unit 36 ​​described later. Therefore, in order to obtain an accurate acquisition interval of the measurement value, the repeated measurement (sampling of the measurement value) of the laser length measuring device 21 is preferably performed according to the reference clock output from the signal generator (not shown).

[0056] Figure 4 : is a graph showing the time change of the standard deviation repeatedly calculated by the standard deviation calculation unit 34 during the repeated measurement of the laser length measuring device 21. Figure 4 The reference numeral 4A indicates the Figure 3 The time variation of the standard deviation when the stage 13 is moved to the measurement point in the first movement example shown in the reference numeral 3A. Figure 4 The reference numeral 4B indicates the Figure 3 The second movement example shown in reference numeral 3B shows the time change of the standard deviation when the stage 13 is moved to the measurement point.

[0057] like Figure 4 As well as the already mentioned Figure 2 As shown in FIG. 1 , the standard deviation calculation unit 34 is equivalent to the index calculation unit of the present invention. The standard deviation calculation unit 34 performs acquisition and temporary storage of the measurement values ​​from the laser length measuring device 21 within the fixed time interval, and calculation of the standard deviation based on the temporarily stored multiple measurement values ​​at every predetermined fixed time interval during the movement of the stage 13. The standard deviation is an index indicating the deviation of the measurement values ​​within the fixed time interval. In addition, other indexes indicating the deviation of the measurement values ​​may be calculated instead of calculating the standard deviation of the measurement values.

[0058] The stationary start time determination unit 35 determines the stationary start time ST (see FIG. 1 ) at which the stage 13 (corner cube 18) is stationary at the measurement point based on the standard deviation repeatedly calculated by the standard deviation calculation unit 34 at fixed time intervals during the movement of the stage 13. Figure 6 ).

[0059] Specifically, when the stage 13 (corner cube 18) moves to the measurement point, the change in the measured value becomes larger, so the standard deviation calculated by the standard deviation calculation unit 34 becomes larger. On the other hand, if the stage 13 is stationary at the measurement point, only the deviation caused by the vibration of the corner cube 18 and the environmental disturbance occurs, so the standard deviation becomes smaller. Therefore, by setting a threshold value Th (refer to Figure 6 ), the stationary start time determination unit 35 can determine whether the stage 13 is stationary based on whether the standard deviation newly calculated by the standard deviation calculation unit 34 is below the threshold value Th. In addition, the threshold value Th is appropriately determined by performing experiments or simulations.

[0060] Then, the stationary start time determination unit 35 determines the time when the standard deviation newly calculated by the standard deviation calculation unit 34 becomes less than the threshold value Th as the stationary start time ST (see Figure 6 ).

[0061] Figure 5 : is a graph showing the time change of the moving speed of the stage 13 repeatedly calculated by the moving speed calculation unit 36 ​​during the repeated measurement of the laser length measuring device 21. Figure 5 The reference numeral 5A indicates the Figure 3 The first movement example shown in the reference numeral 3A causes the temporal change in the movement speed of the stage 13 during the period in which the stage 13 moves to the measurement point. Figure 5 The reference numeral 5B indicates the Figure 3 The second movement example shown in the figure 3B causes the temporal change in the movement speed of the stage 13 during the period in which the stage 13 moves to the measurement point.

[0062] like Figure 5 and the narrated Figure 2 As shown in FIG. 1 , the moving speed calculation unit 36 ​​repeatedly calculates the moving speed of the stage 13 (corner cube 18) during the movement of the stage 13 (during the repeated measurement of the laser length measuring device 21). For example, each time the laser length measuring device 21 obtains a new measurement value, the moving speed calculation unit 36 ​​repeatedly calculates the moving speed of the stage 13 based on the newly obtained measurement value, the measurement value obtained just before it, and the interval between the measurement values ​​(known information). The calculation result of the moving speed calculation unit 36 ​​is used for the waiting time WT (see FIG. 1 ) of the waiting time determination unit 37 described later. Figure 6 ) decision.

[0063] Figure 61 is a graph for explaining the waiting time WT determined by the waiting time determination unit 37. In addition, the reference symbol Q in the figure indicates the start timing of the formal measurement after the movement. In addition, the reference symbol MS in the figure indicates the moving state of the stage 13 before the stationary start time ST, and the reference symbol SS in the figure indicates the stationary state of the stage 13 after the stationary start time ST.

[0064] like Figure 6 and the narrated Figure 2 As shown, the waiting time determination unit 37 determines the waiting time WT from the stationary start time ST determined by the stationary start time determination unit 35 to the start of the formal measurement after the movement. Conventionally (see Patent Document 1), the operator determines the waiting time WT based on a preset condition. Therefore, if the condition is not appropriate, the laser length measuring device 21 acquires the measurement value of the reverberation vibration of the stage 13, or the time until the start of the formal measurement after the movement is unnecessarily delayed.

[0065] Here, the present inventors have found that the behavior of the stage 13 until it moves to the measurement point, specifically, the change in the moving speed of the stage 13 (see Figure 5 ), the appropriate waiting time WT will change. Therefore, the waiting time determination unit 37 is based on the moving speed information 50 (see Figure 7 ), to refer to the pre-generated learning model 37a, thereby automatically determining the appropriate waiting time WT.

[0066] The learned model 37a is generated, for example, using machine learning (supervised learning) based on a known multiple regression model (multiple regression equation, multiple regression analysis) or a machine learning algorithm such as a known convolutional neural network (CNN). The learned model 37a is described below. Figure 8 As shown, the moving speed information 50 of the stage 13 is used as input data (input variable), and the waiting time WT is output as a target variable.

[0067] Figure 7 3 is an explanatory diagram showing an example of teaching data 52 used in machine learning of the learned model 37a. Figure 7 As shown, as teaching data 52 (training data), a data group including moving speed information 50 and an optimal waiting time WT (correct answer label) for each condition when the stage 13 is moved to a measurement point under various moving speed conditions is used.

[0068] The moving speed information 50 includes, for example, the maximum value P1 of the moving speed of the stage 13 and the time variation P2 (acceleration) of the moving speed during the deceleration of the moving speed of the stage 13. As the time variation P2, it is particularly preferable to use the time variation P2 when the moving speed of the stage 13 is rapidly decelerated near the measurement point. The time variation P2 to be included in the moving speed information 50 is not limited to Figure 7 The one point shown may be a plurality of points. In addition, instead of including both the maximum value P1 and the time change P2 in the moving speed information 50 , only one of the maximum value P1 and the time change P2 may be included.

[0069] Based on such teaching data 52, the learning model 37a is generated by the above-mentioned machine learning algorithm. In addition, the algorithm of machine learning is a well-known technology, so the specific description is omitted here. In addition, in the present embodiment, supervised learning is used as an example of machine learning for the learning model 37a, but unsupervised learning, reinforcement learning, transfer learning, etc. can also be used as machine learning.

[0070] Figure 8 3 is an explanatory diagram for explaining an example of determination of the waiting time WT by the waiting time determination unit 37 using the learned model 37a. Figure 8 As shown, the waiting time determination unit 37 determines the waiting time based on the moving speed ( Figure 5 as well as Figure 7 ), to detect the moving speed information 50 (maximum value P1, time change P2). Then, the waiting time determination unit 37 inputs the moving speed information 50 to the learned model 37a, and outputs the waiting time WT.

[0071] return Figure 2 as well as Figure 6 The post-movement measurement control unit 38 (equivalent to the second measurement control unit of the present invention) performs the formal post-movement measurement at the start timing Q based on the still start time ST determined by the still start time determination unit 35 and the waiting time WT determined by the waiting time determination unit 37, when the waiting time WT has passed since the still start time ST.

[0072] The measurement value storage unit 39 stores the measurement values ​​measured by the laser length measuring device 21 in the main measurement before movement and the main measurement after movement as data for confirming the movement accuracy of the stage 13 .

[0073] [Function of the measuring device]

[0074] Fig. 9This is a flowchart showing the flow of a measurement process (a measurement method) of the movement accuracy of the stage 13 of the NC machine tool 10 performed by the measurement device 20 .

[0075] like Fig. 9 As shown, after the corner cube 18 is placed on the stage 13, when the operator starts the measurement of the movement accuracy of the stage 13 on the operation unit (not shown) of the control device 30, the pre-movement measurement control unit 31 controls the laser length measuring device 21 to perform the pre-movement formal measurement (step S1). The measurement value measured by the laser length measuring device 21 in the pre-movement formal measurement is stored in the measurement value storage unit 39.

[0076] If the formal measurement before movement is completed, the movement control unit 32 generates an NC program 32a for moving the stage 13 to the measurement point in the X direction, and outputs the NC program 32a to the NC controller 15. As a result, the NC controller 15 drives the stage moving mechanism 14 based on the NC program 32a to move the stage 13 in the X direction toward the measurement point (step S2A, step S2B is No). Then, the NC controller 15 stops the stage 13 at the measurement point based on the detection result of the position detection sensor (not shown) (step S2B is Yes, step S2C).

[0077] When the stage moving mechanism 14 starts moving the stage 13, the repeated measurement control unit 33 starts repeated measurement by the laser length measuring device 21. Thus, the acquisition of the measurement value of the laser length measuring device 21 is repeatedly performed (step S3A, which corresponds to the first measurement control step of the present invention). The measurement values ​​repeatedly acquired by the laser length measuring device 21 are sequentially output to the standard deviation calculation unit 34 and the moving speed calculation unit 36.

[0078] When repeated measurements are started, the standard deviation calculation unit 34 repeatedly performs temporary storage of the measurement values ​​obtained by the laser length measuring device 21 within the fixed time interval and calculation of the standard deviation of the temporarily stored measurement values ​​at fixed time intervals (step S3B, equivalent to the index calculation step of the present invention). In addition, each time the laser length measuring device 21 obtains a new measurement value, the moving speed calculation unit 36 ​​repeatedly performs calculation of the moving speed of the stage 13 (step S3B, equivalent to the moving speed calculation step of the present invention).

[0079] Then, the stationary start time determination unit 35 monitors whether the standard deviation calculated by the standard deviation calculation unit 34 at fixed time intervals is less than the threshold value Th (No in step S4). Then, the stationary start time determination unit 35 performs the above-mentioned Figure 6As shown, the time when the standard deviation newly calculated by the standard deviation calculation unit 34 becomes less than the threshold value Th is determined as the still start time ST, and the still start time ST is output to the post-movement measurement control unit 38 (step S5, equivalent to the still start time determination step of the present invention).

[0080] In addition, the waiting time determination unit 37 detects the moving speed information 50 (maximum value P1, time change P2) based on the moving speed of the stage 13 repeatedly calculated by the moving speed calculation unit 36. Then, the waiting time determination unit 37 determines the moving speed of the stage 13 as described above. Figure 8 As shown in FIG. 1 , by inputting the detected moving speed information 50 into the learned model 37a, the waiting time WT is output to the post-movement measurement control unit 38 (step S6, which corresponds to the waiting time determination step of the present invention). Thus, the operator does not need to set conditions, and the appropriate waiting time WT corresponding to the moving speed information 50 is automatically determined. In addition, the timing at which the waiting time determination unit 37 determines the waiting time WT may be before the timing at which the stationary start time determination unit 35 determines the stationary start time ST.

[0081] The post-movement measurement control unit 38, which has received the input of the stationary start time ST and the waiting time WT, monitors whether the waiting time WT has elapsed from the stationary start time ST (No in step S7). Figure 6 As shown, at the start timing Q after the waiting time WT has passed from the stationary start time ST, the laser length measuring device 21 is controlled to perform the actual measurement after movement (step S8, which corresponds to the second measurement control step of the present invention).

[0082] The measurement value measured by the laser length measuring device 21 in the post-movement formal measurement is stored in the measurement value storage unit 39 (step S9). Thus, the movement accuracy (the difference between the target movement amount and the actual movement amount) of the stage 13 is obtained based on the measurement values ​​of the pre-movement formal measurement and the post-movement formal measurement stored in the measurement value storage unit 39. At this time, the control device 30 may also calculate the movement accuracy of the stage 13 based on the measurement values ​​stored in the measurement value storage unit 39, and display it on a display unit (not shown).

[0083] In addition, when the stage 13 is repeatedly moved to the next measurement point and then formally measured after the movement to the next measurement point, the above-mentioned processing of step S1 to step S9 is repeatedly performed. In this case, in the accuracy measurement of the NC machine tool 10, it is required to make the interval between the measurement points (measurement interval) uneven (ISO230-2). This means that there is a difference in the maximum value P1 of the movement speed of the stage 13 between the measurement points, but in the present invention, it is possible to automatically determine the appropriate waiting time WT according to the movement speed information 50.

[0084] As described above, the measuring device 20 of this embodiment can determine the appropriate waiting time WT corresponding to the moving speed information 50 of the stage 13 by detecting the moving speed information 50 during the movement of the stage 13 and inputting it into the learned model 37a. As a result, the operator can automatically determine the appropriate waiting time WT without setting any conditions, so that it is possible to prevent the laser length measuring device 21 from obtaining a measurement value containing a deviation that the operator does not want at the measurement point, or to prevent the start time of the formal measurement after the movement from being delayed unnecessarily. As a result, the measurement value at the measurement point of the laser length measuring device 21 can be obtained under more appropriate conditions than before.

[0085] In addition, when the Z-direction movement accuracy of the processing tool holding part 11 is measured by the measuring device 20, for example, the emission direction of the measurement light L1 from the laser interference unit 24 held in the processing tool holding part 11 is switched to the Z-direction lower side, and the corner cube 18 is provided on the Z-direction lower side of the laser interference unit 24. Then, the control device 30 controls the NC controller 15 to move the processing tool holding part 11 to a given measurement point in the Z direction, and performs the formal measurement of the laser length measuring device 21 before and after the movement. In this case, as in the case of measuring the movement accuracy of the stage 13, the formal measurement after the movement of the laser length measuring device 21 can be performed under appropriate conditions.

[0086] [other]

[0087] In the above-mentioned embodiment, the movable body (stage 13, processing tool holding part 11) of the NC machine tool 10 for measuring the moving accuracy and the reflector (the object of measuring the distance of the laser length meter 21) for reflecting the measuring light L1 emitted from the laser length meter 21 are separate bodies, but the movable body and the reflector may be integrated, or a part of the movable body may be used as a reflector.

[0088] In the above embodiment, for example, the corner cube 18 is moved integrally with the stage 13 when the moving accuracy of the stage 13 is measured. However, when the processing tool holding portion 11 is provided with the corner cube 18 instead of the laser length measuring device 21, the laser length measuring device 21 may be moved integrally with the stage 13. In other words, it is sufficient to move either the laser length measuring device 21 or the object to be measured.

[0089] In the above-mentioned embodiment, the laser length meter 21 is listed and explained as an example of a length meter for measuring the distance to a measuring object such as a corner cube prism 18, but various known length meters for measuring the distance to a measuring object using other length measurement methods may be used instead of the laser length meter 21.

[0090] In the above-described embodiment, the control device 30 of the measuring device 20 is provided separately from the NC machine tool 10 , but, for example, a control unit (not shown) of the NC machine tool 10 may be made to function as the control device 30 .

[0091] In the above-mentioned embodiment, the waiting time determination unit 37 determines the waiting time WT by inputting the moving speed information 50 into the learning completion model 37a, but the waiting time WT can also be determined based on a pre-generated data table or calculation formula representing the relationship between the moving speed information 50 and the waiting time WT instead of the learning completion model 37a.

[0092] In the above embodiment, the measurement of the movement accuracy of each part of the NC machine tool 10 by the measuring device 20 is described as an example, but the present invention can also be applied to the measurement of the movement accuracy of the moving body (moving mechanism) of various shape measuring devices including non-contact shape measuring devices and contact shape measuring devices. In addition, the measuring device 20 of the present invention can also be applied to the measurement of the movement accuracy of various devices or moving bodies provided in various mechanisms.

Claims

1. A measuring device comprising a length measuring device for acquiring a measured value of a distance to a measuring object, wherein when either the length measuring device or the measuring object moves to a predetermined measuring point, the measured value of the length measuring device is acquired; The measuring device is characterized by comprising: a first measurement control unit that repeatedly executes acquisition of the measurement value of the length measuring device after starting movement of the one direction to the measurement point; an index calculation unit that repeatedly performs calculation of an index representing a deviation of the measurement value based on the measurement value repeatedly obtained by the length measuring device; a stationary start time determination unit that determines a time when the index calculated by the index calculation unit becomes less than a predetermined threshold value as a stationary start time when the one party is stationary at the measurement point; a moving speed calculation unit that repeatedly calculates the moving speed of the one side based on the measurement value repeatedly obtained by the length measuring device and the interval between the measurement values; a waiting time determination unit that determines a waiting time from the stationary start time determined by the stationary start time determination unit to the time when the length measuring device starts formal measurement of the measurement value at the measurement point based on the moving speed information of the one party obtained from the calculation result of the moving speed calculation unit; and The second measurement control unit executes the main measurement of the length measuring device when the waiting time determined by the waiting time determination unit has elapsed from the stillness start time determined by the stillness start time determination unit.

2. The measuring device according to claim 1, wherein The moving speed information includes at least one of a maximum value of the moving speed and a temporal change in the moving speed during a deceleration of the moving speed.

3. The measuring device according to claim 1 or 2, wherein: The index calculation unit performs calculation of the index based on the plurality of measurement values ​​acquired by the length measuring device within the fixed time interval determined in advance at each fixed time interval.

4. The measuring device according to claim 3, wherein: The index calculation unit calculates a standard deviation of the measurement value as the index.

5. The measuring device according to claim 1 or 2, wherein: The waiting time determination unit determines the waiting time using a learned model that takes the moving speed information as an input and outputs the waiting time.

6. The measuring device according to claim 1 or 2, wherein: The measuring device includes a movement control unit that drives a movement mechanism that moves the one party to move the one party to a measurement point.

7. A measuring method of a measuring device, the measuring device comprising a length measuring device for acquiring a measured value of a distance to a measuring object, wherein when either the length measuring device or the measuring object moves to a predetermined measuring point, the measuring method acquires the measured value of the length measuring device, The measuring method of the measuring device is characterized by comprising the following steps: A first measurement control step of repeatedly acquiring the measurement value of the length measuring device after starting the movement of the one direction to the measurement point; an index calculation step of repeatedly calculating an index representing a deviation of the measurement value repeatedly obtained by the length measuring device; a stationary start time determination step of determining a time when the indicator calculated in the indicator calculation step becomes less than a predetermined threshold value as a stationary start time when the one party is stationary at the measurement point; a moving speed calculation step of repeatedly calculating the moving speed of the one side based on the measurement values ​​repeatedly obtained by the length measuring device and the intervals between the measurement values; a waiting time determination step of determining, based on the moving speed information of the one party obtained from the calculation result of the moving speed calculation step, a waiting time from the stationary start time determined in the stationary start time determination step to the time when the length measuring device starts formal measurement of the measurement value at the measurement point; and The second measurement control step is to execute the main measurement of the length measuring device when the waiting time determined in the waiting time determining step has passed since the stillness start time determined in the stillness start time determining step.

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