JP2015178983A - Position measurement device correction method and position measurement device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a correction method for a position measurement device and the position measurement device that enable a stable position correction by suppressing a variation upon obtaining a correction value.SOLUTION: A correction method for position measurement device according to the present invention is a correction method for a position measurement device that moves in a direction along a measurement axis and, after detecting an amount of displacement relative to an origin of a probe detecting a position of an object, corrects an amount of displacement by a preliminarily set correction value to obtain a measurement value. The correction method comprises the steps of: acquiring an amount of detection fluctuation of the amount of displacement relative to a plurality of reference positions provided at a fixed interval in a direction away from the origin along the measurement axis (steps S101 to 103); and process smoothing of a plurality of amounts of detection fluctuation corresponding to the plurality of reference positions to obtain a correction value (step S104).

Description

  The present invention relates to a position measuring device correction method and a position measuring device for measuring the height of an object.

  A position measuring instrument that measures the height of an object is detected by a probe that can move in the direction along the measurement axis, a detector that detects the amount of displacement from the origin of the probe, and a detector A calculation unit that calculates a position such as the height of the object based on the amount of displacement. In such a position measuring device, a correction value for correcting the detection value is set. That is, the height of the block gauge is measured in advance from the origin at a constant interval (for example, an interval of 20 mm), and the error between the reference value of the block gauge and the detected value is stored as a correction value. When measuring the height of the object, the detected value is corrected using the detected value and the correction value corresponding to the detected value, and output (displayed) as the measured value.

  Here, in Patent Document 1, a base placed on a surface plate, a support column erected on the base, a slider provided so as to be movable up and down along the support column, and a height direction of the slider There is disclosed a one-dimensional measuring machine including a displacement detector that detects the amount of displacement and display means that displays the amount of displacement of the displacement detector.

  This one-dimensional measuring machine includes a first correction data table that stores in advance correction data when the slider moves up along the column, and a second correction data table that stores in advance correction data when the slider moves down along the column. A correction data table and control means are provided. Then, the detection value of the displacement detector detected when the slider is raised is corrected by the correction data stored in the first correction data table, and the detection value of the displacement detector detected when the slider is lowered Is corrected by the correction data stored in the second correction data table.

  Patent Document 2 discloses a measuring device that measures a reference scale, an estimated nominal value calculation unit that calculates an estimated nominal value that is estimated as a nominal value of the reference scale, a measured value of the reference scale, and an estimated nominal value. There is disclosed a measuring machine error correction device including a correction amount calculating unit that calculates a correction amount according to the error and a measurement value correcting unit that corrects a measurement value measured by the measuring device according to the correction amount.

  In this measuring machine error correction device, it is possible to automatically obtain a correction amount by simply measuring the reference scale, and to automatically set the correction amount used in the subsequent measurement.

Japanese Patent No. 3696431 Utility Model Registration No. 3128162

  As described above, the correction value used in the position measuring device is data for correcting the displacement (detection value) of the probe detected by the detection unit. The correction value is set for each of a plurality of reference positions provided at a constant interval (for example, an interval of 20 mm) in a direction away from the origin along the measurement axis. The correction value is obtained by measuring the height of the block gauge with a position measuring device and calculating the difference between the detection value obtained by the detection unit and the height (reference value) of the block gauge.

FIGS. 7A and 7B are diagrams illustrating correction values.
FIG. 7A is an example of correction values stored in the storage unit. FIG. 7B illustrates the state of fluctuation of the correction value. 7A and 7B, the horizontal axis represents the position on the measurement axis, and the vertical axis represents the height (reference value) of the block gauge and the detected value when the height of the block gauge is measured. The amount of deviation (correction value) is indicated. The unit of the vertical axis is, for example, μm.

  In the example shown in FIG. 7A, correction values at reference positions provided from the origin (zero point) to 600 mm at intervals of 20 mm along the measurement axis are represented. That is, the plot in FIG. 7A represents the difference (detection deviation) between the reference value of the block gauge having a height of 20 mm, 40 mm, 60 mm, 80 mm,. Yes.

  The position measuring device stores correction values obtained at constant intervals (for example, 20 mm intervals) obtained as shown in FIG. Then, based on the detection value of the position of the object detected by the detection unit, the correction value is read from the storage unit and corrected to obtain a measurement value. For example, when the detected value is 20 mm, a correction value corresponding to 20 mm (+2 μm in FIG. 7A) is read, and a value obtained by subtracting the correction value (+2 μm) from the detected value (20 mm) (19.998 mm) Is output as a measured value. If the detected value is between a plurality of reference positions, the correction values at the reference positions before and after the detected value may be proportionally distributed and subtracted from the detected value.

  However, when detecting the height of each block gauge and obtaining the correction value, the detection value is determined due to the sensor resolution of the detection unit, the assembly accuracy of the slider unit and the column, the vibration of the column, etc. Variations may occur. FIG. 7B shows correction values obtained by measuring the height of the block gauge at very narrow intervals for convenience of explanation. When this correction value is captured as a waveform, a high frequency component is superimposed on a low frequency component. Many of these high-frequency components are considered to be components of detection variation by the detection unit.

  If such a detection variation component is included in the correction value, a stable correction value cannot be obtained, which causes a decrease in accuracy when correcting the detection value.

  An object of the present invention is to provide a position measuring device correction method and a position measuring device capable of performing stable position correction while suppressing variations in obtaining a correction value.

  The correction method of the position measuring instrument of the present invention moves in the direction along the measurement axis, detects the displacement relative to the origin of the probe that detects the position of the object, and then corrects the displacement by the correction value. This is a correction method for a position measuring device that obtains a measurement value. The present invention measures the displacement amount of the measuring element for each of a plurality of reference positions provided at regular intervals in the direction away from the origin along the measurement axis, and the displacement amount with respect to the reference value for each of the plurality of reference positions. And a step of obtaining a correction value by smoothing a plurality of detected deviation amounts corresponding to a plurality of reference positions.

  According to such a configuration, since the detection deviation amount obtained for each of the plurality of reference positions is smoothed to obtain the correction value of the position measuring device, the detector resolution and the mechanism for moving the measuring element are assembled. Variations in correction values due to accuracy and the like can be suppressed.

  In the correction method of the position measuring device of the present invention, the amount of detection deviation at the target position that is one of the plurality of reference positions and the amount of detection deviation at the same number of reference positions on both sides centered on the target position. It is desirable to obtain the correction value by the calculation used. In particular, as the smoothing process, it is desirable to perform a moving average process using a plurality of detected deviation amounts. According to such a configuration, it is possible to disperse the detection variation included in the detection deviation amount at the position of interest by a calculation such as moving average processing.

  The position measuring device of the present invention includes a measuring element, a detection unit, a measurement value calculation unit, and a correction value calculation unit. The probe moves in the direction along the measurement axis and detects the position of the object. The detector detects the amount of displacement relative to the origin of the probe. The measurement value calculation unit obtains the measurement value by correcting the displacement detected by the detection unit with the correction value. The correction value calculation unit causes the detection unit to detect the amount of displacement of the probe relative to the origin for each of a plurality of reference positions provided at regular intervals in a direction away from the origin along the measurement axis, and the detection unit detects the displacement. Based on the displacement amount, a detected deviation amount of the displacement amount with respect to the reference value for each of the plurality of reference positions is obtained, and a plurality of detected deviation amounts corresponding to the plurality of reference positions are smoothed to obtain a correction value.

  According to such a configuration, the detection deviation amount obtained for each of the plurality of reference positions is smoothed to obtain a correction value, which is caused by the resolution of the detection unit, the assembly accuracy of the mechanism for moving the probe, and the like. It is possible to suppress variations in correction values to be performed.

  The position measuring device of the present invention is preferably applied to a height gauge. According to such a configuration, when the height of the object is detected and corrected, variations in obtaining correction values are suppressed, and stable height correction can be performed.

It is a perspective view which illustrates the composition of the position measuring device concerning a 1st embodiment. It is a block block diagram of the position measuring device which concerns on 1st Embodiment. It is a functional block diagram of the measurement system of the position measuring device which concerns on 1st Embodiment. It is a flowchart which illustrates the acquisition method of a correction value. It is a figure which shows the example of a detection deviation | shift amount and a correction value. It is a schematic diagram explaining a modification. It is a figure explaining a correction value.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that, in the present specification and each drawing, the same elements as those described above with reference to the previous drawings are denoted by the same reference numerals, and detailed description thereof is omitted as appropriate.

(First embodiment)
FIG. 1 is a perspective view illustrating the configuration of the position measuring device according to the first embodiment.
As shown in FIG. 1, the position measuring device 1 includes a base 100 placed on a surface plate (not shown) and the like, and a direction attached to the base 100 along the measurement axis (Z-axis direction). A column 110 that extends, a slider unit 15 that is slidable in the Z-axis direction along the column 110, and a probe 10 attached to the slider unit 15 are provided. That is, the position measuring instrument 1 according to the present embodiment is a height gauge that measures the height of an object or the like based on the amount of displacement from the origin of the probe 10 (for example, the lower surface of the base 100).

  In the position measuring instrument 1 according to this embodiment, two parallel columns 110 are erected on the base 100. When the base 100 is fixed on a surface plate or the like, the support column 110 is arranged so as to extend straight in the Z-axis direction. One or a plurality of support columns 110 may be provided, but a plurality of support columns 110 can support the slider portion 15 more stably.

  The slider portion 15 is provided with a hole for allowing the support 110 to pass therethrough. By attaching the slider part 15 so that the pillar 110 penetrates into the hole, the slider part 15 is provided so as to be slidable in the Z-axis direction in which the pillar 110 extends. The slider unit 15 is moved manually or by an electric drive mechanism (not shown).

  The measuring element 10 is fixed to, for example, a side surface of the slider unit 15. For this reason, by sliding the slider portion 15 along the support column 110, the measuring element 10 moves along the support column 110 together with the slider portion 15 in the Z-axis direction. The tip of the probe 10 extends in the lateral direction. When measuring the position of the object, the extended portion of the probe 10 is aligned with the measurement point of the object.

  A display unit 105 and an operation unit 108 are provided in front of the slider unit 15. The display unit 105 includes, for example, a liquid crystal display panel. The display unit 105 displays measurement values such as the height of the object measured by the probe 10.

  When the user presses a desired button on the operation unit 108, various operations such as mode setting and display setting of the position measuring instrument 1 and setting of the origin of the probe 10 are performed. The origin of the probe 10 can be set at an arbitrary position by the user by operating the operation unit 108 in addition to the lower surface of the base 100.

  The control unit 2 is provided inside the slider unit 15. The control unit 2 calculates a measurement value from the detection result of the position of the object, controls each unit in response to an instruction from the operation unit 108, and controls the display content of the display unit 105.

  In the position measuring instrument 1 having such a configuration, in order to measure the position (for example, height) of the measurement point of the object, the object is arranged below the measuring element 10, and the slider portion 15 is placed on the column 110. The tip of the probe 10 is aligned with the measurement point of the object. In this state, the detection unit 20 detects the amount of displacement of the measuring element 10 from the origin. Then, the amount of displacement (detected value) is corrected with a correction value to obtain a measured value, which is displayed on the display unit 105. Thereby, measured values, such as the height of a target object, are obtained.

Next, the function of each part of the position measuring device 1 will be described.
FIG. 2 is a block configuration diagram of the position measuring device according to the first embodiment.
As shown in FIG. 2, the control unit 2, the detection unit 20, and the storage unit 40 are provided in the slider unit 15 of the position measuring device 1. The slider unit 15 is provided with the display unit 105 and the operation unit 108 described above. The control unit 2 includes a measurement value calculation unit 31 and a correction value calculation unit 32. The control unit 2 performs calculation processing in the measurement value calculation unit 31 and the correction value calculation unit 32 and controls the detection unit 20 and the storage unit 40.

  The detection unit 20 detects a change in the signal caused by the displacement of the probe 10 and outputs a displacement amount (detection value) from the origin. The measurement value calculation unit 31 performs a calculation to obtain the measurement value by correcting the detection value output from the detection unit 20 with the correction value stored in the storage unit 40.

  The correction value calculation unit 32 performs a calculation for obtaining a correction value by smoothing the detected deviation detected by the detection unit 20 for each of a plurality of reference positions. That is, the correction value calculation unit 32 causes the detection unit 20 to detect a displacement amount with respect to the origin of the measuring element 10 for each of a plurality of reference positions, and obtains a detection deviation amount for each of the plurality of reference positions from the displacement amount. . Then, a plurality of detected deviation amounts are smoothed to obtain a correction value.

  Thus, the correction value which suppressed the high frequency component contained in the some detection deviation amount can be calculated | required by smoothing the several detection deviation value acquired for every some reference position. This is equivalent to applying a low-pass filter to the detected value.

FIG. 3 is a functional block diagram of the measurement system of the position measuring device according to the present embodiment.
The measurement system of the position measuring device 1 includes a sensor 101, a demodulation circuit 102, a counting circuit 103, an arithmetic circuit 104, a display unit 105, a data output unit 106, and a storage unit 40. The sensor 101, the demodulation circuit 102, and the counting circuit 103 are included in the detection unit 20, and the arithmetic circuit 104 is included in the control unit 2. The sensor 101 is, for example, an optical type or a magnetic type, and outputs a signal (an optical signal or an induced current) that changes according to the amount of displacement of the probe 10.

  The demodulation circuit 102 demodulates the signal output from the sensor 101 into an electric signal such as a pulse signal. The counting circuit 103 receives the pulse signal output from the demodulation circuit 102 and counts the number of signals.

  The arithmetic circuit 104 calculates the amount of displacement (detected value) from the origin of the probe 10 based on the count number counted by the counter circuit 103. For example, the arithmetic circuit 104 obtains the detection value by integrating the distance per count and the count number. The arithmetic circuit 104 may calculate the absolute position of the measuring element 10 based on the signal output from the counting circuit 103. That is, the position measuring device 1 may be either an increment type or an absolute value type.

  The arithmetic circuit 104 corrects the detection value using the correction value stored in the storage unit 40. The corrected value is sent to the display unit 105 as a measured value. The measured value is displayed on the liquid crystal display panel of the display unit 105. The data output unit 106 converts the measurement value into a predetermined data format and outputs it to the outside.

  In such a position measuring instrument 1, it is possible to switch between a “position measurement mode” for measuring the height of an object and a “correction value acquisition mode” for acquiring a correction value. The mode is switched by, for example, button operation by the operation unit 108. Normally, the position of the object is measured by the above-described process in the “position measurement mode”. On the other hand, when the position measuring device 1 is shipped or calibrated, a “correction value acquisition mode” in which a correction value is calculated and stored in, for example, the storage unit 40 is selected.

  In the position measuring instrument 1 according to the present embodiment, in the “correction value acquisition mode”, the correction value calculation unit 32 smoothes the detection deviation amounts at the plurality of reference positions detected by the detection unit 20 to obtain a plurality of pieces. Processing for obtaining a correction value corresponding to the reference position is performed.

Next, a specific example of processing in the “correction value acquisition mode” in the position measuring device 1 will be described.
FIG. 4 is a flowchart illustrating a correction value acquisition method.
First, it is determined whether or not switching to the “correction value acquisition mode” has been performed (step S101). For example, the control unit 2 determines whether or not the user has pressed a mode switching button of the operation unit 108 provided in the slider unit 15.

  When the mode switching button is not pressed, the measurement standby state (position measurement mode) is continued and the position of the object is measured. On the other hand, when the mode switching button is pressed, the control unit 2 switches from the “position measurement mode” to the “correction value acquisition mode”.

  In the “correction value acquisition mode” shown in step S102, the displacement of the probe 10 relative to the origin is measured at a plurality of reference positions provided at regular intervals in the direction away from the origin along the measurement axis, and the detected deviation amount. To get. For example, when correction values are acquired at intervals of 20 mm, the height of the block gauge increased by 20 mm from the 20 mm block gauge is measured in order. The difference (detection deviation amount) between the detection value obtained by measuring each block gauge and the reference value of the block gauge is temporarily stored in the storage unit 40.

  Next, the control unit 2 determines whether or not a detection deviation amount corresponding to the final height block gauge is acquired (step S103). When the detection deviation amount corresponding to the final height block gauge is not acquired, the process returns to step S102, the height of the next height block gauge is detected, and the detection deviation amount is obtained. When the cancel button is pressed during the process of acquiring the detection deviation amount corresponding to the height of the block gauge, the control unit 2 switches from the correction value acquisition mode to the position measurement mode. And shift to the measurement standby state.

  After obtaining the detection deviation amount corresponding to the final height block gauge, the correction value is calculated (step S104). The correction value calculation is performed by the correction value calculation unit 32. The correction value is obtained by a calculation for smoothing the detected deviation amount at each reference position stored in the storage unit 40.

  Here, as an example, a moving average process using three points will be described. Let ML (X) be the amount of detection deviation at measurement positions (reference positions) at regular intervals along the measurement axis from the origin, and let VL (X) be the correction value. X = 0 is the origin, X = 1 is the first reference position from the origin, X = 2 is the second reference position from the origin, ..., X = n (n is a natural number) means the nth reference position from the origin To do.

  In the moving average process using three points, for example, the detection value ML (0) at the origin is used as the correction value VL (0) at the origin (X = 0). For example, the detection value ML (n) at the last reference position is used as it is as the correction value VL (n) at the last reference position (X = n). It should be noted that values obtained by calculation using other methods may be used for the correction value VL (0) of the origin (X = 0) and the correction value VL (n) of the last reference position (X = n). .

From the second reference position to the (n−1) th reference position, the correction value is calculated by the following equation (1).
VL (X) = (ML (X-1) + ML (X) + ML (X + 1) / 3) (1)

  After calculating the correction value VL (X) at each reference position, the correction value calculation unit 32 stores the correction value VL (X) in the storage unit 40 (step S105). After the correction value VL (X) is stored in the storage unit 40, the control unit 2 ends the “correction value acquisition mode” and shifts to the measurement standby state.

  In the above example, the moving average process using three detection deviation amounts is illustrated, but a moving average process other than three points may be used. In this case, the moving average process can be performed using the detected deviation amount at the target position, which is one of the plurality of reference positions, and the detected deviation amounts at the same number of reference positions on both sides around the target position. desirable. When performing another smoothing process, a correction value corresponding to the position of interest may be calculated by applying an expression corresponding to the smoothing process. Thereby, the variation included in the detected deviation amount at the target position can be dispersed, and the high-frequency component included when the detected deviation amount is obtained can be suppressed.

  FIGS. 5A and 5B are diagrams illustrating examples of detection deviation amounts and correction values at regular intervals. FIG. 5A illustrates an example of the reference value and the detection deviation amount at each reference position, and FIG. 5B illustrates an example of the reference value and the correction value at each reference position. In the “correction value acquisition mode”, the storage unit 40 temporarily stores detection deviation amounts at regular intervals as shown in FIG. 5A, for example, as table data.

  When calculating the correction value at regular intervals, the correction value calculation unit 32 reads the detection deviation amount at regular intervals shown in FIG. 5A and performs smoothing processing (for example, moving average processing) to correct the correction value. Calculate the value. As shown in FIG. 5B, the correction value obtained by the calculation is stored as table data at regular intervals, for example.

  When measuring the position of the object in the position measurement mode, the measurement value calculation unit 31 reads the correction value as shown in FIG. 5B from the storage unit 40 and corrects the detection value of the position of the object. The measured value is calculated. In the correction value shown in FIG. 5B, since the influence of detection variation is suppressed, a stable measurement value can be obtained by correcting the detection value using this correction value. .

  As described above, in the position measuring device 1 according to the present embodiment, since the detection value of the position of the object is corrected using the smoothed correction value, stable position correction can be performed. . For this reason, sufficient measurement accuracy can be obtained by stable correction when the sensor 101 having a low resolution is used or when the assembly accuracy of the support 110 and the slider unit 15 is not increased more than necessary. Thereby, the influence by the detection variation resulting from the resolution of the sensor 101 of the detection unit 20 and the assembly accuracy of the mechanism for moving the probe 10 is suppressed, and a stable correction value can be obtained.

(Modification)
FIG. 6 is a schematic diagram illustrating a modification.
The position measuring device 1 shown in FIG. 6 is configured to perform processing in the correction value acquisition mode described in the first embodiment outside the position measuring device 1. For example, the processing in the “correction value acquisition mode” is executed by the program processing by the computer 200 connected to the position measuring device 1. That is, in the position measuring instrument 1 according to the modification, the processing in the “correction value acquisition mode” is realized by a program that can be executed by the computer 200.

  In the example shown in FIG. 6, the position measuring device 1 is connected to the computer 200 via a cable 300. The position measuring device 1 and the computer 200 may be connected via wireless communication or may be connected via a communication line such as the Internet. The computer 200 may be a mobile terminal.

  For example, the computer 200 executes a program corresponding to the processing in steps S102 to S105 in the flowchart illustrated in FIG. Here, when the mode switching button of the operation unit 108 of the position measuring instrument 1 is pressed, the control unit 2 transmits a signal to the computer 200 indicating that the mode has been switched to the “correction value acquisition mode”.

  Receiving this signal, the computer 200 enters preparations for executing a program corresponding to the processes in steps S102 to S105. The computer 200 receives the detection value sent via the cable 300 from the detection unit 20 of the position measuring device 1 and performs a process of acquiring a detection deviation amount corresponding to each reference position. After outputting the detected value at the last reference position, the control unit 2 sends a signal to that effect to the computer 200. In response to this signal, the computer 200 executes a program corresponding to the processes in steps S104 to S105. By executing this program, detection deviation amounts at a plurality of reference positions are smoothed, and correction values are calculated. The computer 200 performs a process of storing the calculated correction value in the storage unit 40.

  According to the configuration in which the correction value is calculated by the program executed by the computer 200 as in the position measuring device 1 according to the modified example, when the algorithm of the detection deviation amount smoothing process is changed, only the program is rewritten. Can be changed easily.

  This program may be recorded on a computer-readable recording medium or distributed via a network.

  As described above, according to the position measuring device correction method and position measuring device according to the present embodiment, it is possible to perform stable position correction while suppressing variations in obtaining correction values.

  Although the present embodiment has been described above, the present invention is not limited to these examples. For example, various methods such as a simple moving average, a weighted moving average, and an exponential moving average can be applied to the moving average process by the correction value calculation unit 32. The smoothing process may be other than the moving average process. For example, smoothing processing using a filter (such as a Gaussian filter) using a predetermined coefficient may be performed.

  Further, in the embodiment described above, the correction value smoothed in advance is stored in the storage unit 40, and the correction value stored in the storage unit 40 is read and used for correction in the position measurement. The storage unit 40 stores a detection deviation amount when the block gauge is detected, and when detecting and correcting the position of the object, the detection deviation amount stored in the storage unit 40 is read and smoothed. A correction value may be obtained and used for correction.

  In addition, as long as a person skilled in the art appropriately adds, deletes, and modifies the design of the above embodiment, and appropriately combines the features of the above embodiment, the present invention also includes the gist of the present invention. , Within the scope of the present invention.

  The present invention can be suitably used not only for height gauges but also for calipers, micrometers, linear scales, and three-dimensional measuring machines.

  DESCRIPTION OF SYMBOLS 1 ... Position measuring device, 2 ... Control part, 10 ... Measuring element, 15 ... Slider part, 20 ... Detection part, 31 ... Measurement value calculating part, 32 ... Correction value calculating part, 40 ... Memory | storage part, 100 ... Base, DESCRIPTION OF SYMBOLS 101 ... Sensor, 102 ... Demodulation circuit, 103 ... Count circuit, 104 ... Arithmetic circuit, 105 ... Display part, 106 ... Data output part, 108 ... Operation part, 110 ... Support | pillar, 200 ... Computer, 300 ... Cable

Claims (5)

A correction method for a position measuring instrument that moves in a direction along a measurement axis and detects a displacement amount with respect to the origin of a probe that detects the position of an object and then obtains a measurement value by correcting the displacement amount with a correction value Because
The displacement of the probe is measured for each of a plurality of reference positions provided at regular intervals in a direction away from the origin along the measurement axis, and the displacement with respect to a reference value for each of the plurality of reference positions Obtaining a detection deviation amount of the quantity;
Smoothing a plurality of detection deviation amounts corresponding to the plurality of reference positions to obtain the correction value;
A position measuring device correction method comprising:   The smoothing processing is an operation using a detection deviation amount at a target position that is one of the plurality of reference positions and detection deviation amounts at the same number of reference positions on both sides centering on the attention position. The position correction device correction method according to claim 1, wherein the correction value is obtained by:   3. The position measuring device correction method according to claim 1, wherein the smoothing process is a moving average process using the plurality of detected deviation amounts. A probe that moves in the direction along the measurement axis and detects the position of the object,
A detector for detecting a displacement with respect to the origin of the probe;
A measurement value calculation unit that obtains a measurement value by correcting the displacement detected by the detection unit with a correction value;
For each of a plurality of reference positions provided at regular intervals in a direction away from the origin along the measurement axis, the amount of displacement of the probe relative to the origin is detected by the detection unit and detected by the detection unit. Based on the displacement amount, a detection deviation amount of the displacement amount with respect to a reference value for each of the plurality of reference positions is obtained, and a plurality of the detection deviation amounts corresponding to the plurality of reference positions are smoothed to perform the correction. A correction value calculation unit for obtaining a value;
A position measuring device comprising:   The position measuring device according to claim 4, wherein the position measuring device is a height gauge.

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