Surface measurement device and measurement method of an object

Abstract

The present invention discloses a surface measurement device for an object. The surface measurement device for an object includes: a support portion for placing the object to be measured; at least three probes for measuring the surface of the object to be measured; and a driving portion for relatively driving one of the support portion and the at least three probes with respect to the other.

Description

[0001] This application is a divisional application of the application filed on May 8, 2019, with the application number "201980030769.9" and the invention title "Object Surface Measurement Device and Measurement Method". Technical Field

[0002] The present invention relates to a measurement device and a measurement method for measuring the surface of an object. Background Art

[0003] A surface measurement device is a device for measuring the surface of an object. Generally, during relative driving of one of the object to be measured and a sensor with respect to the other, the surface measurement device acquires a measurement signal for measuring the surface of the object to be measured in the above sensor.

[0004] However, the measurement signals acquired in the above sensor flow in and are detected together with the driving error component based on the above relative driving and the shape error component of the object to be measured. In this case, without delicately separating the above error components from the above measurement signals, the measurement inaccuracy will increase. Specifically, when measuring the shape of the object to be measured, due to the driving error caused by the above relative driving, the measurement inaccuracy will increase. On the contrary, when measuring the driving error component, the shape error of the measurement reference part flows into the measurement signal and becomes the cause of the measurement error. As a result, the inaccuracy of the error motion measurement result will increase.

[0005] As a countermeasure against the above problems, a precision measurement device is used. The precision measurement device has problems such as high cost and large size of the device and can only be used in a limited measurement environment, and also has disadvantages such as being difficult to measure in real time. Summary of the Invention

[0006] Technical Problem

[0007] One technical problem to be solved by the present invention is to provide a surface measurement device and a measurement method for an object as follows, that is, the surface shape of the object to be measured moving relatively linearly can be precisely measured by linear driving.

[0008] Moreover, other technical problems to be solved by the present invention are to provide a surface measurement device and a measurement method as follows, that is, the surface shape of the object to be measured performing relative rotational motion can be precisely measured.

[0009] Technical Solution

[0010] The surface measurement device for an object of the present invention includes: a support part for placing the object to be measured; at least three probes for measuring the surface of the above object to be measured; and a driving part for relatively driving one of the above support part and the above at least three probes with respect to the other.

[0011] Furthermore, the present invention may further include a probe support portion located on one side of the support portion for supporting the at least three probes. The driving portion relatively linearly drives one of the support portion and the at least three probes with respect to the other, and the at least three probes may be arranged at a predetermined interval on a straight line parallel to the relative linear driving direction.

[0012] Furthermore, the present invention may further include an arithmetic unit that combines the measurement signals received by the at least three probes to generate a composite signal, and removes the driving error signal generated during the relative linear driving and the surface shape error signal of the measurement object from the composite signal.

[0013] Furthermore, the at least three probes may include a first probe to a third probe, and the ratios of the distance between the first probe and the second probe to the measurement length of the measurement object and the distance between the second probe and the third probe to the measurement length of the measurement object are respectively represented as irreducible fractions.

[0014] Furthermore, the first probe to the third probe may be combined with the same side surface among the multiple side surfaces of the probe support portion.

[0015] Furthermore, the first probe to the third probe may be respectively located at the same height.

[0016] Furthermore, the first probe to the third probe may separately measure the surface change of the measurement object along the same path through the relative linear driving.

[0017] Furthermore, the arithmetic unit may perform a Fourier transform on the signal obtained by removing the driving error signal from the composite signal to obtain a signal in which harmonic components are linearly combined. When the ratio of the distance between the first probe and the second probe to the measurement length of the measurement object is defined as an irreducible fraction (a L / T / b L / T ), and the ratio of the distance between the second probe and the third probe to the measurement length of the measurement object is defined as an irreducible fraction (a R / T / b R / T ), among the harmonic components, the ratio (λ min ) of the wavelength of the shortest wavelength harmonic to the wavelength (λ max ) of the longest wavelength harmonic (λ max / λ min ) is less than the least common multiple of the above b L / T and b R / T .

[0018] Furthermore, the above-mentioned probe support part may include: a first support area facing one side surface of the above-mentioned measurement object; and a second support area facing the other side surface of the above-mentioned measurement object. The above-mentioned at least 3 probes include: a first probe to a third probe combined with the above-mentioned first support area and arranged in a row on a straight line parallel to the above-mentioned relative linear driving direction; and a fourth probe to a sixth probe combined with the above-mentioned second support area and arranged in a row on a straight line parallel to the above-mentioned relative linear driving direction.

[0019] Furthermore, the above-mentioned at least 3 probes may further include a seventh probe to a ninth probe combined with the above-mentioned second support area and arranged in parallel with the above-mentioned fourth probe to the sixth probe.

[0020] Furthermore, the above-mentioned driving part enables one of the above-mentioned support part and the above-mentioned at least 3 probes to rotate relative to the other around the center of the above-mentioned measurement object. Based on the center of the above-mentioned measurement object, the above-mentioned at least 3 probes are located at positions where the angle between the probes is greater than 0 degrees and less than 180 degrees.

[0021] Furthermore, the ratio of the angle between one probe and another probe among the above-mentioned at least 3 probes to the angle between the one probe and another probe may be an irreducible fraction.

[0022] Furthermore, based on the center of the above-mentioned measurement object, the above-mentioned at least 3 probes may be respectively arranged at non-facing positions.

[0023] Furthermore, the present invention may further include an arithmetic unit that combines the measurement signals received by the above-mentioned at least 3 probes to generate a composite signal, and removes the driving error signal and the shape error signal of the above-mentioned measurement object that occur during the above-mentioned relative rotational movement from the above-mentioned composite signal. The arithmetic unit obtains a signal in which harmonic components are linearly combined by performing a Fourier transform on the signal obtained by removing the above-mentioned driving error signal from the above-mentioned composite signal. The rotation device defines the total measurement range angle when the sampling angle (Δ) rotates the set number of signal reception times (N) as T, and defines the ratio of the above-mentioned total measurement range angle (T) to the angle between one probe and another probe as an irreducible fraction (a α / b α ). When the ratio of the above-mentioned total measurement range angle (T) to the angle between one probe and another probe is defined as (a β / b β ), among the above-mentioned harmonic components, the ratio (λ min ) of the wavelength (λ max ) of the shortest-wavelength harmonic to the wavelength (λ max ) of the longest-wavelength harmonic (λ min ) is less than bα and b β the value obtained by removing 1 from the least common multiple of {LCM(b α , b β ), -1} and the ratio (r T = T° / 360°) of the total measurement range angle (T) for one rotation of 1.

[0024] Moreover, the surface measurement method of the object of the present invention may include: a step of relatively driving one of the support portion for placing the measurement object and at least 3 probes located on one side of the support portion with respect to another; and a step of measuring the surface of the measurement object among the at least 3 probes during the relative driving to generate a measurement signal.

[0025] Moreover, the present invention may further include: a step of combining the measurement signals to generate a combined signal; a step of removing the driving error signal generated during the relative driving from the combined signal; and a step of removing the surface shape error signal of the measurement object from the combined signal after removing the driving error signal. In the step of removing the surface shape error signal of the measurement object from the combined signal after removing the driving error signal, a Fourier transform is performed on the combined signal after removing the driving error to obtain a signal in which harmonic components are linearly combined.

[0026] Moreover, in the step of performing the relative driving, the support portion and one of the at least 3 probes may be relatively linearly driven with respect to another, and the at least 3 probes are arranged at a predetermined interval on a straight line parallel to the relative linear driving direction to measure the surface of the measurement object.

[0027] Moreover, the at least 3 probes may include a first probe to a third probe, and the ratio of the distance between the first probe and the second probe with respect to the measurement length of the measurement object and the ratio of the distance between the second probe and the third probe with respect to the measurement length of the measurement object are each presented as an irreducible fraction.

[0028] Moreover, in the step of performing the relative driving, the support portion and one of the at least 3 probes may be relatively rotated with respect to another about the center of the measurement object, and based on the center of the measurement object, the at least 3 probes are located at positions where the angle between the probes is greater than 0 degrees and less than 180 degrees.

[0029] Moreover, the ratio of the angle between one probe and another probe among the at least 3 probes and the angle between the one probe and other probes may be presented as an irreducible fraction.

[0030] Effects of the Invention

[0031] According to an embodiment of the present invention, surface shape information for removing a drive error signal caused by relative movement and a drive error signal of a linear drive unit can be obtained from measurement signals measured by a plurality of probes. Thus, the present invention can precisely measure the surface shape of the measurement object.

[0032] Moreover, according to an embodiment of the present invention, the surface measurement device can obtain surface shape information for removing a drive error signal caused by relative rotational movement and a rotational error movement of a rotational drive unit from measurement signals measured by a plurality of probes. Thus, the present invention can precisely measure the shape of the circumferential surface of the measurement object. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A diagram showing a surface measurement device for an object having a linear cross-sectional shape according to a first embodiment of the present invention;

[0034] Figure 2 A top view of a surface measurement device for an object having a linear cross-sectional shape with Figure 1 ;

[0035] Figure 3 A flowchart for explaining a surface measurement method according to an embodiment of the present invention;

[0036] Figure 4 A diagram for explaining Figure 3 a surface measurement method;

[0037] Figure 5 A diagram showing a surface measurement device for an object having a linear cross-sectional shape according to a second embodiment of the present invention;

[0038] Figure 6 A diagram showing a surface measurement device for an object having a linear cross-sectional shape according to a third embodiment of the present invention;

[0039] Figure 7 A diagram for explaining a method of adding a shape measurement unit to a surface measurement device for an object having a linear cross-sectional shape according to an embodiment of the present invention;

[0040] Figure 8 A flowchart for explaining a method of measuring shape information according to an embodiment of the present invention;

[0041] Figure 9 A diagram showing a surface measurement device for an object according to a fourth embodiment of the present invention;

[0042] Figure 10 A diagram showing Figure 9 a top view of a surface measurement device for an object;

[0043] Figure 11 A diagram showing a surface measurement device including a probe holder;

[0044] Figure 12 A flowchart for explaining a surface measurement method according to another embodiment of the present invention;

[0045] Figure 13 For explaining Figure 12 A diagram of the surface measurement method;

[0046] Figure 14 A diagram showing a surface measurement device for an object according to a fifth embodiment of the present invention;

[0047] Figure 15 A diagram showing a surface measurement device for an object according to a sixth embodiment of the present invention;

[0048] Figure 16 A diagram showing a surface measurement device for an object according to a seventh embodiment of the present invention;

[0049] Figure 17 A diagram for explaining a method of measuring the shape of an object by a surface measurement device according to an embodiment of the present invention. Detailed Description of the Invention

[0050] The surface measurement device for an object of the present invention includes: a support part for placing the object to be measured; at least three probes for measuring the surface of the object to be measured; and a driving part for relatively driving one of the support part and the at least three probes with respect to the other.

[0051] Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in detail. However, the technical idea of the present invention is not limited to the embodiments described herein, but can be embodied in other forms. On the contrary, the embodiments introduced herein are provided to make the disclosed content complete and to fully convey the idea of the present invention to those of ordinary skill in the technical field to which the present invention pertains.

[0052] In this specification, when it is mentioned that one structural element is located on another structural element, this means that it can be directly formed on the other structural element, and a third structural element can be formed between them. Also, in the drawings, the thickness of the shape and region is enlarged for effective explanation of the description content.

[0053] Also, in various embodiments of the present specification, terms such as first, second, third, etc. are used to describe various structural elements, and these structural elements are not limited to the above terms. These terms are only used to distinguish two structural elements. Therefore, a component referred to as the first structural element in one embodiment may be referred to as the second structural element in other embodiments. Each embodiment described and illustrated herein includes its complementary embodiment. Also, in the present specification, "and / or" includes at least one of the structural elements listed before and after.

[0054] In the specification, as long as it is not clearly indicated in the context, the singular representation includes the plural representation. Also, terms such as "comprising" or "having" are used to specify the existence of features, numbers, steps, structural elements, or combinations thereof described in the specification, and do not exclude the existence or additional possibility of one or more other features, numbers, steps, structural elements, or combinations thereof. Also, in the present specification, "connection" includes both indirect connection and direct connection of multiple structural elements.

[0055] Also, hereinafter, in the process of describing the present invention, when it is determined that the specific description of a related well-known function or structure makes the gist of the present invention unclear, the detailed description thereof will be omitted.

[0056] Figure 1 A diagram of a surface measurement device for an object showing a first embodiment of the present invention, Figure 2 To show Figure 1 A top view of the surface measurement device of the object.

[0057] Referring to Figure 1 The surface measurement device 1000 of the object may include a support portion 100, a probe support portion 200, a drive portion (not shown), a probe 300, and an arithmetic portion (not shown).

[0058] The support portion 100 may be in the shape of a quadrilateral plate having a predetermined thickness. The measurement object O is placed on the upper surface of the support portion 100. The measurement object O is an object having a predetermined shape and has a predetermined length along one direction. The measurement object O has a linear cross-sectional shape. Hereinafter, the length direction of the measurement object O is defined as the X-axis direction, the direction perpendicular to the above X-axis direction on the horizontal plane is defined as the Y-axis direction, and the direction perpendicular to the X-axis direction and the Y-axis direction is defined as the Z-axis direction.

[0059] The probe support portion 200 may be provided on one side of the support portion 100, for example, at a predetermined distance along the -Y axis direction. The probe support portion 200 may be in the shape of a quadrilateral plate having a predetermined thickness.

[0060] A driving unit (not shown) can relatively move one of the support unit 100 and the probe support unit 200 with respect to the other. For example, the driving unit can relatively linearly drive (relative linear motion, M) one of the support unit 100 and the probe support unit 200 with respect to the other along the X-axis direction.

[0061] According to one example, the above driving unit can linearly drive (M) the support unit 100 in a state where the probe support unit 200 is fixedly arranged. According to another embodiment, the above driving unit can linearly drive (M) the probe support unit 200 in a state where the support unit 100 is fixedly arranged. In this embodiment, an example will be described in which the driving unit linearly drives (M) the support unit 100.

[0062] At least three probes 300 are formed, and the probe support unit 200 is arranged at a specified height. At least three probes 300 are located at the same height along the Z-axis direction.

[0063] At least three probes 300 output signals to the surface of the linearly driven measurement object O, and receive the signals reflected from the surface of the measurement object O to generate measurement signals. At least three probes 300 individually generate the above measurement signals.

[0064] During the linear driving of the measurement object O, at least three probes 300 can generate the above measurement signals at a set number of times (N) and intervals (Δ). The measurement length (T) of the measurement object O is determined according to the number of times (N) and intervals (Δ) of the above measurement signals generated by at least three probes 300.

[0065] Refer to Figure 2 , at least three probes 300 can be arranged on the probe support unit 200 at positions that satisfy the following condition 1 and condition 2. Hereinafter, for the convenience of explanation, an example will be described in which at least three probes 300 include a first probe 300a, a second probe 300b, and a third probe 300c, and the first probe 300a, the second probe 300b, and the third probe 300c are arranged in sequence along the X-axis direction.

[0066] Condition 1

[0067] The first probe 300a, the second probe 300b, and the third probe 300c are arranged in a row along the X-axis direction, on the same line, at positions spaced apart by a set distance (X R 、X L ).

[0068] The first probe 300a, the second probe 300b, and the third probe 300c are at the same height and arranged on the same straight line along the X-axis direction so that their arranged positions do not overlap with each other. Moreover, the first probe 300a, the second probe 300b, and the third probe 300c are all supported by the probe support portion 200. The first probe 300a, the second probe 300b, and the third probe 300c are arranged at a set distance apart on the same side surface among the multiple side surfaces of the probe support portion 200. The set distance between the first probe 300a, the second probe 300b, and the third probe 300c is based on Condition 2 described below. Thus, the first probe 300a, the second probe 300b, and the third probe 300c are driven linearly relative to the measurement object O and substantially cross the surface along the same path, individually reacting to the surface changes of the measurement object O to output measurement signals.

[0069] Condition 2

[0070] As shown in the following Mathematical Formula 1, among the first probe 300a, the second probe 300b, and the third probe 300c that satisfy the above Condition 1, for the distance (x L ) between the first probe 300a and the second probe 300b with respect to the measurement length (T) of the measurement object O, the ratio (r R ) can be presented as an irreducible fraction. And, as shown in the following Mathematical Formula 2, for the distance (x R ) between the second probe 300b and the third probe 300c with respect to the measurement length (T) of the measurement object O, the ratio (r L ) can be presented as an irreducible fraction.

[0071] Mathematical Formula 1

[0072] r L = x L / T = a L / T / b L / T

[0073] Mathematical Formula 2

[0074] r R = x R / T = a R / T / b R / T

[0075] On the other hand, after removing the driving error signal from the combined signal obtained by combining the above measurement signals and performing Fourier transform, the combined signal from which the driving error signal has been removed by Fourier transform can be represented by a linear combination of harmonic components. Among them, the wavelength (λ min ) of the harmonic component with the shortest wavelength and the wavelength (λ max) The ratio can be expressed by the following mathematical formula 3. In this case, as shown in the following mathematical formula 3, the above wavelength ratio (r λ ) value is less than b which is the denominator of the mathematical formula 1 R / T and b which is the denominator of the mathematical formula 2 L / T 's least common multiple (LCM(b R / T , b L / T ))).

[0076] Mathematical formula 3

[0077] r λ = λ max / λ min < LCM(b R / T , b L / T )

[0078] Next, referring to Figure 1 , the operation unit (not shown) can receive the above measurement signals from at least 3 probes 300, and can generate a composite signal obtained by synthesizing the above measurement signals. In this case, the above composite signal includes the above drive error signal generated during the relative linear motion (M) and the above shape error signal generated by measuring the surface shape of the object O. Due to the above errors, the measurement inaccuracy of the above measurement signals may increase. To prevent the above problems, the above operation unit can apply a multi-probe error separation method based on the Fourier model to the above measurement signals to remove the above drive error signal or the above shape error signal as needed. By Figures 5 to 6 explaining the specific process of the above error separation method.

[0079] As described above, referring to Figures 1 to 2 , the surface measurement device 1000 of an embodiment of the present invention has been described. Hereinafter, referring to Figures 3 to 4 , a surface measurement method of an embodiment of the present invention will be described.

[0080] Figure 3 is a flowchart for explaining the surface measurement method of an embodiment of the present invention, Figure 4 is a diagram for explaining Figure 3 's surface measurement method.

[0081] Referring to Figure 3, The surface measurement method of the above object may include: Step S110 of relatively moving one of the support part or at least three probes relative to the other; Step S120 of generating a measurement signal among at least three probes; Step S130 of combining the measurement signals to generate a combined signal; Step S140 of removing a driving error signal from the combined signal; and Step S150 of removing a shape error signal from the combined signal after removing the driving error signal.

[0082] Step S110 of relatively moving one of the support part or at least three probes relative to the other is the step of the above driving part relatively moving one of the support part 100 or the probe support part 200 relative to the other. According to an embodiment, in the above Step S110, the above driving part may linearly drive the support part 100 in a state where the probe support part 200 is fixedly arranged. According to another embodiment, the above driving part may linearly drive the probe support part 200 in a state where the support part 100 is fixedly arranged.

[0083] Step S120 of generating a measurement signal among the above at least three probes is the following step, that is, using at least three probes 300 to measure the surface of the above measurement object O. At least three probes 300 output signals to the surface of the linearly driven measurement object O, and receive the signals reflected from the surface of the above measurement object O to generate a measurement signal.

[0084] Refer to Figure 4 , At least three probes 300 may separately measure one side of the measurement object O moving linearly relative along the X-axis direction. In this case, at least three probes 300 may measure N times at a specified interval (Δ) to collect N data sets {m}.

[0085] When the first probe 300a, the second probe 300b, and the third probe 300c are respectively defined as P L , P O and P R , and the sets of data measured by P L , P O and P R are respectively defined as m L , m O and m R , in the case of the i-th measurement position X i , the data sets m L , m O , m R of the above first probe 300a, second probe 300b, and third probe 300c obtained are data sets with the region of ±Δ / 2 as the measured space centered on X i . In this case, the relationship between the measurement length T and the measurement interval Δ can be expressed by the following mathematical formula 4.

[0086] Mathematical formula 4

[0087] x i = i·Δ

[0088] T = Δ·N

[0089] where i = 0, 1, 2, 3, … N-1

[0090] Among the first probe 300a, the second probe 300b, and the third probe 300c, if the position of the second probe 300b as a reference is set as the origin to define the measurement coordinate system, the position coordinates X of the first probe 300a, the second probe 300b, and the third probe 300c set in the X-axis direction PO , X PL and X PR can be expressed by the following Mathematical formula 5.

[0091] Mathematical formula 5

[0092] x PO = x dO + e xO O

[0093] x PL = -x dL + e xL

[0094] x PR = x dR + e xR

[0095] x d = x d4 + x dR

[0096] In this case, the above x dO is the set position (designed Position) in the measurement coordinate system of the second probe 300b. In other words, it is the origin of the measurement coordinate system, and e xO is the setting error along the X-axis direction in the position where the second probe 300b is set. The above x dL is the set position in the measurement coordinate system of the first probe 300a, and e xL is the setting error along the X-axis direction in the position where the first probe 300a is set. The above x dR is the set position in the measurement coordinate system of the third probe 300c, and e xR is the setting error along the X-axis direction in the position where the third probe 300c is set. X d is the distance in the X-axis direction from the first probe 300a to the third probe 300c.

[0097] In the same manner, the position coordinates Y of the first probe 300a, the second probe 300b, and the third probe 300c in the Y-axis direction are set PO , Y PL and Y PR can be expressed by the following mathematical formula 6.

[0098] Mathematical formula 6

[0099] y PO = y dO (= 0) + e yO (= 0) = 0

[0100] y PL = y dL (= 0) + e yL = e yL

[0101] y PR = y dR (= 0) + e yR = e yR

[0102] In this case, the above Y dO is the set position (designed Position) in the measurement coordinate system of the above second probe 300b. In other words, it is the origin of the measurement coordinate system, and e yO is the setting error along the Y-axis direction at the position where the second probe 300b is set. The above Y dL is the set position in the measurement coordinate system of the first probe 300a, and e yL is the setting error along the Y-axis direction at the position where the first probe 300a is set. The above Y dR is the set position in the measurement coordinate system of the third probe 300c, and e yR is the setting error along the Y-axis direction at the position where the third probe 300c is set.

[0103] The step S130 of generating a composite signal by combining the above measurement signals is the following step, that is, combining the data sets {m Li}, {m Oi}, and {m Ri} of the above measurement signals measured by the first probe 300a, the second probe 300b, and the third probe 300c to generate a composite signal simultaneously obtained at the measurement position X i .

[0104] Specifically, the first probe 300a, the second probe 300b, and the third probe 300c, in other words, the above P L, P O and P R At the i-th measurement position X i The data sets {m Li}, {m Oi}, and {m Ri} may include images based on setting errors of the remaining two probes P O for the reference probe P L and probe P R and shape error components R(X i ), rotational error movement angle θ(X i ), and horizontal movement error y(X i ) of the measurement object O. One or more of the above data sets {m Li}, {m Oi}, and {m Ri} can be expressed as in Mathematical Formula 7.

[0105] Mathematical Formula 7

[0106] m Li = R(x i + x PL )+(x i + x PL )·{θ S + θ z (x i ))+{y s + y(x i )}+ y PL

[0107] = R(x i - x dL + e dR )+(x i - x dL + e xR )·{θ s + θ z (x i )}+{y S + y(x i )}+ e yL

[0108] m Oi = R(x i + x PO )+(x i + x PO )·{θ S + θ z (x i )}+{y S + y(x i )}+ y PO

[0109] = R(x i ) + x i ·{θ s + θ E (xi)} + {y S + y(x i )}

[0110] m Ri = R(x i + x PR ) + (x i + x PR )·{θ S + θ z (x i )} + {y S + y(x i )} + y PR

[0111] = R(x i + x dR + e xR ) + (x i + x dR + e xR )·{θ S + θ z (x i )} + {y S + y(x i )} + e yR

[0112] In this case, θ s is the inclination between the above relative linear drive direction and the horizontal axis of the above probe, θ z is the minute rotational error angle based on the drive error, and y s is the error distance of the above measurement object O in the Y-axis direction.

[0113] In the case where the X-axis direction setting error of the above probe is strictly corrected and can be ignored, the above mathematical formula 7 can be expressed as mathematical formula 8.

[0114] Mathematical formula 8

[0115] m Oi = R(x i ) + x i ·{θ S + θ z (x i )} + {y S + y(x i )}

[0116] m Li = R(x i - xdL )+(x i -x dL )·{θ S +θ z (x i )}+{y S +y(x i )}+e yL

[0117] m Ri =R(x i +x dR )+(x i +x dR ){θ S +θ z (x i )}+{y S +y(x i )}+e yR

[0118] And, when the error in the Y-axis direction of the above probe can be ignored due to strict modification, the above mathematical formula 8 can be expressed as mathematical formula 9.

[0119] Mathematical formula 9

[0120] m Oi =R(x i )+x i ·{θ S +θ z (x i )}+{y S +y(x i )}

[0121] m Li =R(x i -x dL )+(x i -x dL )·{θ S +θ z (x i )}+{y S +y(x i )}

[0122] m Ri =R(x i +x dR )+(x i +x dR )·{θ S +θ z (x i )}+{y S +y(x i )}

[0123] In this case, θ s is the inclination between the relative linear drive direction and the horizontal axis of the second probe 300b, and θ z is the minute rotational error angle based on the drive error, and y s is the error distance of the measurement object O in the Y-axis direction.

[0124] In other words, at N specimen extraction positions X i (i = 0, 1, 2…N-1), the measurement signals m L , P o and P R are detected. Li , m Oi and m Ri . In this case, the output data m Oi of the second probe 300b as a reference can be added to the data m Li , m Ri of the remaining first probe 300a and third probe 300c, which are respectively multiplied by the constant a and the constant b. Thus, a data set {M i} composed of the load amounts M i of the detection signals simultaneously obtained at the measurement position X i can be obtained. The above data set {M i} can be defined by the following mathematical formula 10.

[0125] Mathematical formula 10

[0126] {M i} = {M i |M i = m Oi + a·m Li + b·m Ri , i = 0, 1, 2,..., N}

[0127] Therefore, from the above mathematical formulas 7 to 9, the load amount M i constituting the data set {M i} can be expressed by the following mathematical formula 11.

[0128] Mathematical formula 11

[0129] M i = m Oi + a·m Li + b·m Ri

[0130] = R(x i ) + (x i )·{θ S + θ z (x i)}+{y S +y(x i )}+a·[R(x i +x PL )+(x i +x PL )·{θ S +θ s (x i )}+{y S +y(x i )}+y PL +b·[R(x i +x PR )+(x i +x PR )·{θ S +θ s (x i ))+{y S +y(x i )}+y PR

[0131] =R(x i )+aR(x i +x PL )+b·R(x i +x PR )+y PO +a·y PL +b·y PR +(1 + a + b)·[x i ·{θ S +θ z (x i )}+{y S +y(x i )}+(a·x PL +b·x PR )·{θ S +θ z (x i )}

[0132] =R(x i )+a·R(x i - x dL )+b·R(x i +x dR )+C P +(1 + a + b)·[x i ·{θ S +θ z (x i )}+{y S +y(x i )}](-a·x dL +b·x dR )·{θ​S +θ z (x i )}

[0133] Among them, C P = y PO + a·y PL + b·y PR = a·e yL + b·e yR

[0134] The step S140 of removing the drive error signal from the above composite signal is the following step, that is, the above operation unit removes the above drive error in the above load amount (M i ).

[0135] In this case, the above drive error may include one or more of the error caused by setting the measurement object O and the error movement angle and horizontal movement error in the rotation direction of the drive unit.

[0136] In this case, the error caused by setting the above measurement object O may include the angular error (θ s ) between the above relative linear drive direction and the horizontal axis of the above probe or the error distance y s of the above measurement object O in the Y-axis direction, or one or more of them.

[0137] According to the embodiment, the above operation unit can derive the constants a and b of the above load amount that satisfy the conditions of Mathematical Formula 12.

[0138] Mathematical Formula 12

[0139] 1 + a + b = 0

[0140] x PO + a·x PL + b·x PR = a·x PL + b·x PR = -a·x dL + b·x dR = O

[0141] Thus, the above operation unit can represent the constants a and b of the above load amount as the following Mathematical Formula 13.

[0142] Mathematical Formula 13

[0143]

[0144]

[0145] If the a and b derived from the above mathematical formula are substituted into the above Mathematical Formula 11, the load amount M iIt can be expressed by mathematical formula 14.

[0146] Mathematical formula 14

[0147]

[0148] Thus, the above operation unit applies to M i The load sum of the output values obtained from at least three probes 300 can be used to remove the above drive error signal.

[0149] On the contrary, it is also possible to have a method in which the above output values respectively have sensitivity ratios of 1, a, and b. For reference, in the case of the embodiment, the above a and b can be expressed by the following mathematical formula 15.

[0150] Mathematical formula 15

[0151] a = -x F / (x R +x F )

[0152] b = -x R / (x R +x F )

[0153] The step S150 of removing the shape error signal from the composite signal for removing the above drive error signal is the following step, that is, the above operation unit removes the shape error signal from the composite signal for removing the above drive error signal through Fourier transform.

[0154] Specifically, the above operation unit can perform Fourier transform (Fourier transformation) after removing the average value from the above M i . Thus, a signal (M w ) in the frequency domain expressed by the linear combination of harmonic components can be derived. The above M w can be expressed by mathematical formula 16.

[0155] Mathematical formula 16

[0156]

[0157] In this case, the above-mentioned T is the total measurement length of the measurement object O measured N times by the surface measurement device 1000 with a linear profile shape at a prescribed interval (Δ), and the above-mentioned k (bin number) is a positive integer determined according to the accuracy of the surface profile to be measured as needed in the components of the signal represented by the sum of harmonic components, and can be defined as k = 1, 2, 3... k Max . The above-mentioned w k is each angular frequency, and λ k is the wavelength of the harmonic corresponding to the k-th one, and can be presented by the relationship of λ k = T / k

[0158] Also, the shape component R(x) of the measurement profile presented for the rotational position x can also be represented by the following Fourier model R w . The above-mentioned R w can be represented as in Mathematical Formula 17

[0159] Mathematical Formula 17

[0160]

[0161] If the above-mentioned M in the above-mentioned Mathematical Formula 16 w and the above-mentioned R in the above-mentioned Mathematical Formula 17 w are substituted into Mathematical Formula 11 obtained from the actual measurement data, it can be represented as in Mathematical Formula 18

[0162] Mathematical Formula 18

[0163]

[0164] In this case, for convenience, if A k and B k are substituted into Mathematical Formula 19, the above-mentioned load amount M wi can be represented as in the following Mathematical Formula 20

[0165] Mathematical Formula 19

[0166] α k = 1 + acosω k x dL + bcosω k x dR

[0167] β k = asinω k x dL - bsinω k x dR

[0168] Mathematical formula 20

[0169]

[0170]

[0171] In this case, the above F k and G k are the coefficients of M wi .

[0172] Through the above Mathematical formula 20, the above operation unit can derive a coefficient comparison formula such as Mathematical formula 21.

[0173] Mathematical formula 21

[0174]

[0175] If the above Mathematical formula 19 is applied, the above operation unit can use the data obtained from the above first probe 300a, second probe 300b, and third probe 300c and the Fourier transform result of the above load amount derived through the above Mathematical formula 14 to derive the coefficient of the profile shape component R wi of the above object to be measured O as in Mathematical formula 22.

[0176] Mathematical formula 22

[0177]

[0178] The obtained R wi can be obtained through inverse Fourier transform. Finally, the estimated value of the shape component R(x i ) expressed in the space domain can be calculated.

[0179] Different from the above embodiment, in the process of using the coefficient comparison method in the above frequency region by the existing measurement method, when the above load constants a, b and the above bin number k involved in the Fourier transform process satisfy specific conditions, α k and β k of the above Mathematical formula 19 are both 0, resulting in a calculation error.

[0180] Specifically, the above load constants a, b and the above bin number k are independent of the coefficients F wi and G k of the load amount M calculated from the actual measurement data k , and are determined by the specimen interval Δ, the measurement length T(=Δ·N), and the probe configuration conditions. Therefore, a situation where Mathematical formula 23 is satisfied simultaneously can occur.

[0181] Mathematical formula 23

[0182] α k = 1 + acosω k x dL + bcosω k x dR = 0

[0183] β k = asinω k x dL - bsinω k x dR = 0

[0184] When the above Mathematical formula 23 satisfies the above conditions, the determinant of each variable row of the coefficient comparison formula of the above Mathematical formula 21 is 0, so it is impossible to perform matrix inversion as in the above Mathematical formula 22. Due to the above phenomenon, problems may occur in the process of calculating the magnitude of the corresponding frequency component, so the above problem may be the cause of serious errors in the calculation results.

[0185] However, according to an embodiment of the present invention, as the positions where the above specimen interval Δ, the above measurement length (T), and the arrangement conditions of the above probes simultaneously satisfy the above Conditions 1 to 2, α of the above Mathematical formula 19 k and β k are both 0, thus preventing calculation errors. Therefore, in the case of no calculation errors, shape errors can be removed from the measurement signal, and shape information with drive error and shape error components removed can be obtained.

[0186] Figure 5 FIG. for showing the surface measurement device of the object of the second embodiment of the present invention.

[0187] Refer to Figure 5 and, different from the embodiment of Figure 1 , the above drive unit 400 can linearly drive (M) the probe support unit 200 along the axial direction. In this case, the probe support unit 200 can be placed on the drive unit 400.

[0188] The probe support unit 200 may include: a first support area 200a, which is separated by a predetermined distance along the -Y axis direction with respect to the measurement object O; and a second support area 200b, which is separated by a predetermined distance along the +Z axis direction with respect to the measurement object O.

[0189] According to an embodiment, one side surface of the second support area 200b may be fixed to the upper end of the first support area 200a. According to an example, the first support area 200a and the second support area 200b may be combined into an "┓" shape.

[0190] According to an embodiment, at least three probes 300 may include a first probe 300a, a second probe 300b, and a third probe 300c that are combined with the first supporting region 200a and arranged in a row along the X-axis direction. According to an embodiment, the first probe 300a, the second probe 300b, and the third probe 300c are arranged at positions that simultaneously meet the above conditions 1 and 2.

[0191] Furthermore, at least three probes 300 may further include a fourth probe 300d, a fifth probe 300e and a sixth probe 300f combined with the second supporting region 200b and arranged in a row along the X-axis direction. According to an embodiment, the fourth probe 300d, the fifth probe 300e and the sixth probe 300f are arranged at positions that simultaneously meet the above conditions 1 and 2.

[0192] Figure 6 FIG. 3 is a diagram showing a surface measuring apparatus for an object having a linear cross-sectional shape according to a third embodiment of the present invention.

[0193] Reference Figure 6 ,and Figure 5 Different from the embodiment, the at least three probes may further include a seventh probe 300g, an eighth probe 300h and a ninth probe 300i. The seventh probe 300g, the eighth probe 300h and the ninth probe 300i are combined with the second supporting area 200b and arranged in a row along the X-axis direction.

[0194] According to an embodiment, the seventh probe 300g, the eighth probe 300h and the ninth probe 300i may be arranged at positions that simultaneously satisfy the above-mentioned conditions 1 to 2. Furthermore, the seventh probe 300g, the eighth probe 300h and the ninth probe 300i may be arranged side by side with the fourth probe 300d, the fifth probe 300e and the sixth probe 300f. According to an example, the seventh probe 300g may be located on the same straight line along the Y-axis direction as the fourth probe 300d, the eighth probe 300g may be located on the same straight line along the Y-axis direction as the fifth probe 300e, and the ninth probe 300i may be located on the same straight line along the Y-axis direction as the sixth probe 300f.

[0195] Figure 7 1 is a diagram for explaining a method of adding a shape measuring unit to a surface measuring device of an object having a linear cross-sectional shape according to an embodiment of the present invention. Figure 8 It is a flowchart for explaining the method of measuring shape information according to an embodiment of the present invention.

[0196] Reference Figure 7 ,and Figure 6 According to different embodiments, the surface measuring device 1000 may further include a second supporting portion 120 .

[0197] The second support part 120 may be in the shape of a quadrilateral plate with a specified thickness. The second object to be measured O2 is placed on the upper surface of the second support part 120. The second object to be measured O is an object for obtaining shape information and has a specified length along the X-axis direction.

[0198] Moreover, the probe support part 200 may further include a third support area 200c that is spaced apart from the second object to be measured O2 by a specified distance along the +Z-axis direction.

[0199] According to an embodiment, one side surface of the third support area 200c may be fixed to the upper end of the second support area 200b. According to an example, the first support area 200a and the third support area 200c are also combined into an "L" shape and may be combined in a direction opposite to the direction in which the first support area 200a and the second support area 200b are combined. From another perspective, the third support area 200c, the second support area 200b, the first support area 200a, and the drive part 400 may be sequentially fixed along the -Z-axis direction.

[0200] According to an embodiment, at least three probes 300 may further include a shape measurement probe 310 that is combined with the third support area 200c. The shape measurement probe 310 may be located at a position that is spaced apart from the second object to be measured O2 by a specified distance along the +Z-axis direction and may emit a signal to the surface of the second object to be measured O2 that moves linearly relative to it. Moreover, the shape measurement probe 310 receives the signal reflected from the surface of the second object to be measured O2 to generate a shape signal.

[0201] According to an embodiment, the above arithmetic unit may use the drive error signal derived from the object to be measured O to remove the drive error signal of the second object to be measured O2. By Figure 8 Describe the process of removing the drive error signal of the second object to be measured O2 above.

[0202] Refer to Figure 8 , the method for removing the drive error signal of the above shape signal may further include: step S240, by Figure 3 , in the above step S110, step S120, and step S130, derive the drive error signal in the composite signal; and step S250, remove the drive error of the shape signal. Among them, the method of step S240 for deriving the drive error signal in the composite signal is similar to that of step S140 for removing the drive error signal in the composite signal. Therefore, the detailed description thereof will be omitted.

[0203] Step S250 for removing the driving error of the shape signal is as follows, that is, substituting the driving error signal derived in the above step S240 into the above shape signal. Among them, the above shape signal is the signal for measuring the surface of the second measurement object O2 in the shape measurement probe 310. In this case, the above shape signal includes the driving error signal. Specifically, the driving unit 400 can linearly drive the probe support unit 200 and the shape measurement probe 310 along the X-axis direction. In this case, due to the above linear motion, the above shape signal may include the driving error. Therefore, the accurate shape information of the second measurement object O2 cannot be derived only from the above shape signal.

[0204] To prevent the above situation, the above operation unit can modify the above shape signal based on the driving error signal derived in step S240 and can remove the driving error of the above shape signal. Thus, the linear surface measurement device 1000 can derive the accurate shape information of the second measurement object O2.

[0205] Figure 9 FIG. showing the surface measurement device of the object according to the fourth embodiment of the present invention, Figure 10 For showing Figure 9 the top view of the surface measurement device of the object, Figure 11 FIG. showing the surface measurement device including the probe holder.

[0206] Referring to Figures 9 to 11 , the surface measurement device 1000 of the object may include a support unit 100, a measurement unit 200, a flat plate 300, a driving unit (not shown), and an operation unit (not shown).

[0207] The support unit 100 may be in the shape of a plate with a specified thickness. The measurement object O is placed on the upper end of the support unit 100. The measurement object O may have a specified shape, for example, a cylindrical shape. The measurement object O has a specified length extending in one direction. Hereinafter, the length direction of the measurement object O is defined as the Z-axis direction, and the directions perpendicular to the above Z-axis direction are respectively defined as the X-axis direction and the Y-axis direction.

[0208] The measurement unit 200 may be located at a position spaced apart in one direction along the support unit 100, for example, at a position spaced apart by a specified distance along the +Z-axis direction. The measurement unit 200 may include at least 3 probes 210. Figure 9 In, only the first probe 210a, the second probe 210b, and the third probe 210c are shown, but it is obvious to those of ordinary skill in the art to which the present invention pertains that there may also be more than three probes. The above at least 3 probes 210 are located at the same height along the Z-axis direction.

[0209] At least one of the at least three probes 210 or the measurement object O performs a relative rotational movement (R) with respect to the other. In this case, the at least three probes 210 can measure the surface shape of the measurement object O that performs the relative rotational movement. Specifically, the at least three probes 210 output signals to the surface of the measurement object O that performs the relative rotational movement, and receive the signals reflected from the surface of the measurement object O to generate measurement signals. The at least three probes 210 individually generate the above-mentioned measurement signals.

[0210] The at least three probes 210 can generate the above-mentioned measurement signals during the rotational movement of the measurement object O. Specifically, the at least three probes 210 rotate the measurement object O by a multiple of the sampling angle (Δ) according to the set number of signal receptions (N) to generate the above-mentioned measurement signals. In this case, the degree of rotation of the measurement object O is defined as the measurement range angle (T).

[0211] According to the embodiment, the at least three probes 210 satisfy the following condition 3, and at the same time, are located at one or more positions that satisfy condition 4 or condition 5. Hereinafter, for the convenience of explanation, an example will be given in which the at least three probes 210 include a first probe 210a, a second probe 210b, and a third probe 210c.

[0212] Condition 3

[0213] Based on the center of the measurement object O, the first probe 210a, the second probe 210b, and the third probe 210c are located at positions where the angle between the probes is greater than 0 degrees and less than 180 degrees. Specifically, in one of the first probe 210a, the second probe 210b, and the third probe 210c, the angle formed by the segment connecting the center of the measurement object and the segments connecting the center of the measurement object in the other two probes cannot be 0 degrees or 180 degrees. Thus, the arrangement positions of the first probe 210a, the second probe 210b, and the third probe 210c do not overlap or face each other.

[0214] Condition 4

[0215] The ratio of the angle between one probe and another probe among the first probe 210a, the second probe 210b, and the third probe 210c to the total measurement range angle (T) can be presented as an irreducible fraction. For example, the ratio of the total measurement range angle (T) to the angle between the first probe 210a and the second probe 210b can be presented as an irreducible fraction as shown in the following mathematical formula 24, and the ratio of the total measurement range angle (T) to the angle between the first probe 210a and the third probe 210c can be presented as an irreducible fraction as shown in the following mathematical formula 25 (a β / b β ).

[0216] Mathematical formula 24

[0217] r1 = a α / b α

[0218] Mathematical formula 25

[0219] r2 = a β / b β

[0220] On the other hand, after removing the drive error signal from the composite signal obtained by combining the above measurement signals, a Fourier transform is performed. Through the Fourier transform, the composite signal from which the above drive error signal has been removed is represented by a linear combination of harmonic components. Among them, the ratio (r Min ) of the wavelength (λ Max ) of the harmonic component with the shortest wavelength and the wavelength (λ λ ) of the harmonic component with the longest wavelength should be less than the product of the value {LCM(b α , b β ) - 1} obtained by removing 1 from the least common multiple of the denominators of r1 and r2 and the ratio (r T = T° / 360°) of the total measurement range angle (T) for one rotation angle. In other words, the above r λ , LCM(b α , b β ) - 1, and r T need to satisfy the following Mathematical formula 26.

[0221] Mathematical formula 26

[0222] r λ = λ max / λ min < r T ·{LCM(b α , b β ) - 1}

[0223] Condition 5

[0224] The ratio (r Min ) of the wavelength (λ Max ) of the harmonic component with the shortest wavelength and the wavelength (λ λ ) of the harmonic component with the longest wavelength should be less than the numerator a T of r T (r T = T° / 360° = a T / b T ) which is an irreducible fraction representing the ratio of the total measurement range angle (T) for the above one rotation angle. In other words, the following Mathematical formula 27 needs to be satisfied.

[0225] Mathematical formula 27

[0226] r λ = λ max / λ min <a T

[0227] The flat plate 300 has a predetermined thickness, and a plane for placing a predetermined object is formed at the upper end of the flat plate 300. According to an embodiment, the support portion 100 can be placed at the upper end of the flat plate 300.

[0228] A drive unit (not shown) can cause one of the support portion 100 and the measurement portion 200 to perform a relative rotational movement (R) with respect to the other with the center of the measurement object O as a reference. According to an example, the drive unit can cause the support portion 100 to perform a rotational movement (R) in a state where the measurement portion 200 is fixedly provided. According to another example, the drive unit can cause the measurement portion 200 to perform a rotational movement (R) in a state where the support portion 100 is fixedly provided. In the present embodiment, an example where the drive unit causes the support portion 100 to perform a rotational movement (R) will be described.

[0229] An arithmetic unit (not shown) can receive the measurement signals from at least three probes 210 to generate a composite signal that composites the measurement signals. In this case, the composite signal includes the drive error signal that occurs in the relative rotational movement (R) and the shape error signal that occurs through the surface shape of the measurement object O. Due to the above errors, the measurement inaccuracy of the measurement signal may increase. To prevent the above phenomenon, the arithmetic unit can apply a multi-probe error separation method based on a Fourier model to the measurement signals to remove the drive error signal and the shape error signal. Through Figure 12 The specific process of the above error separation method will be described later.

[0230] According to an embodiment, as Figure 11 shown, the measurement portion 200 of the surface measurement device 1000 may further include a probe support portion 230 that fixes the probe 210.

[0231] The probe support portion 230 has a column shape with a predetermined length extending along the +Z axis. The probe support portion 230 is fixed to the upper end of the flat plate 300 and connects the flat plate 300 and the probe 210. Thus, the probe support portion 230 can stably fix the probe 210 to the flat plate 300 and can limit the movement of the probe 210.

[0232] Above, with reference to Figures 9 to 11 , the surface measurement device 1000 for an object having a circular cross-sectional shape according to an embodiment of the present invention has been described. Hereinafter, with reference to Figure 12 , a surface measurement method according to an embodiment of the present invention will be described.

[0233] Figure 12 is a flowchart for explaining a surface measurement method according to another embodiment of the present invention, Figure 13 for explaining Figure 12 the surface measurement method of

[0234] Referring to Figure 12 , the surface measurement method of an object having the above circular cross-sectional shape may include: Step S110 of relatively rotating one of the support part or the measurement part with respect to the other; Step S120 of measuring the circumferential surface of the object to be measured among at least 3 probes to generate a measurement signal; Step S130 of synthesizing measurement information to generate a composite signal; Step S140 of removing a drive error signal from the composite signal; and Step S150 of removing a shape error signal from the composite signal after removing the drive error signal.

[0235] Step S110 of relatively rotating one of the support part or the measurement part with respect to the other is a step in which the above drive part relatively rotates one of the support part 100 or the measurement part 200 with respect to the other (R). According to an example, in the above step S110, the drive part may rotate the support part 100 with respect to the center of the object to be measured O in a state where the measurement part 200 is fixedly arranged. According to another example, the drive part may rotate the measurement part 200 with respect to the center of the object to be measured O in a state where the support part 100 is fixedly arranged.

[0236] Step S120 of measuring the circumferential surface of the object to be measured among at least 3 probes to generate a measurement signal is a step in which the circumferential surface of the object to be measured O is measured by using at least 3 probes 210. At least 3 probes 210 output signals to the circumferential surface of the object to be measured O that is rotating, and receive the signals reflected from the circumferential surface of the object to be measured O to generate a measurement signal.

[0237] Referring to Figure 13 , the first probe 210a, the second probe 210b, and the third probe 210c may be respectively defined as P O , P Φ and P ψ . In this case, the above P O is a reference probe, and P Φ and P ψ are probes respectively set at angles Φ and ψ separated from P O . According to the above condition 1, neither of the angles Φ and ψ can be 0 degrees or 180 degrees.

[0238] The above P O , PΦ and P ψ can measure the circumferential surface of the object to be measured O that makes a relative rotational motion (R) with respect to the center of the object to be measured O. Specifically, the above-mentioned P O , P Φ and P ψ can collect N data sets {m} by measuring the set number of signal receptions (N) at a specified sampling angle (Δ). The i-th acquired measurement data is affected by the horizontal movement components X(θ i ), Y(θ i ) of the central axis caused by the driving and setting errors at the moment of measurement and the shape components of the measured cross-sectional part measured by multiple probes, and can be expressed by the following mathematical formula 28.

[0239] Mathematical formula 28

[0240] m Oi = R(θ i ) + x(θ i )

[0241] m φi = R(θ i - φ) + x(θ i )cosφ + y(θ i )sinφ

[0242] m ψi = R(θ i + ψ) + x(θ i )cosψ - y(θ i )sinψ

[0243] In this case, M oi is the position coordinate measured by P O at the i-th position, M Φi is the position coordinate measured by P Φ at the i-th position, and M ψi is the position coordinate measured by P ψ at the i-th position.

[0244] On the other hand, even if a commonly used probe is precisely set, offset errors such as initial value setting errors will occur. Considering the offset errors of the above-mentioned multiple probes, the above mathematical formula 28 can be expressed by the following mathematical formula 29.

[0245] Mathematical formula 29

[0246] m Oi = R(θ i ) + x(θ i ) + θ o

[0247] mφi = R(θ i - φ) + x(θ i ) cos φ + y(θ i ) sin φ + θ φ

[0248] m ψi = R(θ i + ψ) + x(θ i ) cos ψ - y(θ i ) sin ψ + θ ψ

[0249] Referring again to Figure 12 , the step S130 of generating a composite signal by combining the measurement signals is as follows. That is, the above-mentioned P O , P Φ and P ψ are combined up to the set of the i-th measurement data {m oi}, {m Φi} and {m ψi} to generate a composite signal.

[0250] According to the embodiment, the estimation of the measured profile shape component by the (harmonic function) coefficient comparison method for measuring the frequency band of the driving part profile is performed through the following steps.

[0251] 1) Based on the geometric relationship of the measurement system, construct a model of the measurement data measured in the form of the sum of the measured profile shape component and the driving error component.

[0252] 2) Define the unknown shape component R i existing in the measured profile, its Fourier model R wi and the Fourier model M i of the composite signal M oi = m i + a·mΦ ψi . wi .

[0253] 3) Select the load constants a and b in such a way as to remove the terms based on the driving error and the design error from the actual measurement data Mo i , M Φi and m ψi , and obtain the composite signal M i = M oi + a·M Φi + b·m ψi = R(θ i ) + a·R(θ i - Φ) + b·R(θ i + ψ).

[0254] 4) Apply the Fourier transform to M i to obtain the Fourier coefficients of M wi .

[0255] 5) Apply the coefficient comparison method to calculate the shape component R wi from the coefficients of M wi to obtain R wi .

[0256] 6) Separate the shape component R wi by the inverse Fourier transform of R i .

[0257] According to the above process, the above composite signal can be obtained by the product of the load constants a and b suitable for the above mathematical formula 29. That is, the above composite signal can be expressed as the following mathematical formula 30.

[0258] Mathematical formula 30

[0259] M i = m Oi + am φi + bm ψi

[0260] = R(θ i ) + aR(θ i - φ) + bR(θ i + ψ) + (1 + αcosφ + bcosψ)·x(θ i ) + (αsinφ - bsinψ)·y(θ i ) + e O + ae φ + be ψ

[0261] = R(θ i ) + aR(θ i - φ) + bR(θ i + ψ) + (1 + αcosφ + bcosψ)·x(θ i ) + (asinφ - bsinψ)·y(θ i ) + C P

[0262] where C P = θ O + θ φ + bθ ψ

[0263] The step S140 of removing the drive error signal from the composite signal is the following step, that is, the above operation unit removes the above drive error and setting error from the above composite signal (M i ).

[0264] In the above mathematical formula 30, by selecting appropriate a and b, the terms containing x i and y i can be removed, and the terms affected by the driving error are removed. Thus, the above mathematical formula 30 can be expressed as the following mathematical formula 31.

[0265] Mathematical formula 31

[0266] M i = m Oi + am φi + bm ψi + C P

[0267] = R(θ i ) + αR(θ i - φ) + bR(θ i + ψ) + C P

[0268] To make the above composite signal M i not affected by the driving error and the setting error, the terms containing x i and y i corresponding to the error components need to be removed. Therefore, the load constants a and b for satisfying the above conditions need to satisfy the following mathematical formula 32.

[0269] Mathematical formula 32

[0270] 1 + a cos φ + b cos ψ = 0

[0271] a sin φ - b sin ψ = 0

[0272] Due to the above probe configuration condition, sin ψ cannot be 0. Therefore, the above load constant b can be b = a·sin Φ / sin ψ. If the above b value is substituted into the above mathematical formula 32 and sorted out, the above mathematical formula 32 can be sorted out as the following mathematical formula 33.

[0273] Mathematical formula 33

[0274] 1 + a cos φ + (a sin φ / sin ψ) cos ψ = 0

[0275] sin ψ + a cos φ sin ψ + a sin φ cos ψ = 0

[0276] sin ψ + a sin(φ + ψ) = 0

[0277] Therefore, considering the probe configuration condition sin(Φ + ψ) ≠ 0, the constant a and the constant b can be determined as the following mathematical formula 34.

[0278] Mathematical formula 34

[0279] a = -sinψ / sin(φ + ψ)

[0280] b = -sinφ / sin(φ + ψ)

[0281] The above driving error signal and setting error can be eliminated by substituting a and b derived in the above mathematical formula 34 into the above mathematical formula 30 or mathematical formula 31.

[0282] Step S150 of eliminating the shape error signal from the composite signal after eliminating the driving error signal is as follows, that is, the above operation unit eliminates the shape error signal from the above composite signal after eliminating the driving error signal through Fourier transform.

[0283] The actual measurement data M obtained from N measurement positions using 3 probes oi , M Φi and M ψi , and the load amount data column M obtained using the load constant i can be represented by the Fourier model M wi through Fourier transform. In this case, M wi is represented by the following mathematical formula 35.

[0284] Mathematical formula 35

[0285]

[0286] And if the shape component R i of the measurement profile line is also represented by the following Fourier model R wi , then it can be similar to the case of the above M wi . The above R wi is represented by the following mathematical formula 36.

[0287] Mathematical formula 36

[0288]

[0289] In the above mathematical formula 35 and mathematical formula 36, when performing data processing considering the aliasing effect, only the bin number k of the effective wavelength component is limited to K = 1, 2, 3... k Max . In this case, the above K Max is the largest integer not exceeding the standard number N / 2 determined by the Nyquist Theorem.

[0290] If the above mathematical formula 35 and mathematical formula 36 are applied to the mathematical formula 31 obtained from the actual measurement data, it is represented by the following mathematical formula 37.

[0291] Mathematical formula 37

[0292]

[0293] In this case, if the 1 + a·cosω in the above mathematical formula 37 k Φ + b·cosω k ψ is replaced with α k and the a·sinω k Φ - b·sinω k ψ is replaced with β k then the above mathematical formula 37 can be rearranged into the following mathematical formula 38.

[0294] Mathematical formula 38

[0295]

[0296] Therefore, if the above mathematical formula 32 is compared with the above mathematical formula 38, it is expressed as the following mathematical formula 39.

[0297] Mathematical formula 39

[0298]

[0299] The coefficient comparison formula as the following mathematical formula 40 can be derived from the above mathematical formula 39.

[0300] Mathematical formula 40

[0301]

[0302] If the above formula is applied, from the data obtained through actual measurement, from the Fourier transform result of the load obtained through the above mathematical formula 40 the coefficient of the measured profile shape component R wi can be easily calculated In this case, the above is expressed as the following mathematical formula 41.

[0303] Mathematical formula 41

[0304]

[0305] If the R calculated through the above mathematical formula 41 wi is inverse-transformed, the estimated value of the shape component R expressed in the spatial domain is finally calculated i

[0306] Different from the above embodiment, in the existing measurement method, serious calculation errors will occur in the process of calculating the coefficient of R w

[0307] ​​However, according to an embodiment of the present invention, at least three probes 210 satisfy the above condition 3, and at the same time, are arranged at one or more positions satisfying condition 4 or condition 5, and the above measurement range angle (T) and the arrangement angles ψ and Φ of the probes will be limited. Thereby, the situation of causing calculation errors can be prevented. Thereby, in the case of no calculation error, the shape error can be removed from the measurement signal, and the shape information removing the driving error and the shape error components can be obtained.

[0308] Figure 14 FIG. for showing a surface measurement device of an object according to the fifth embodiment of the present invention.

[0309] Referring to Figure 14 , different from the embodiment of Figure 11 , a measurement object O in a tube shape providing a predetermined space is formed inside, and is placed on a flat plate 300. A measurement unit 200 is formed inside the measurement object O. The measurement unit 200 includes at least three probes 210 and at least three probe holders 230, and the at least three probe holders 230 correspond to the at least three probes. Based on the center of the measurement object O, the first probe 210a, the second probe 210b, and the third probe 210c are separated by the same distance and are respectively arranged along the direction toward the inner surface of the measurement object O.

[0310] According to the embodiment, the first probe 210a, the second probe 210b, and the third probe 210c are respectively fixed to the upper end of the support part 100 through the first probe holder 230a, the second probe holder 230b, and the third probe holder 230c. The support part 100 makes a rotational motion (R) based on the center of the measurement object O through a driving part (not shown), and in this case, the first probe 210a, the second probe 210b, and the third probe 210c also make a rotational motion (R) based on the center of the measurement object O. Thereby, the surface measurement device 1000 measures the surface shape of the circumferential surface inside the measurement object O having a tube shape.

[0311] Figure 15 FIG. for showing a surface measurement device of an object according to the sixth embodiment of the present invention.

[0312] Referring to Figure 15 , different from the embodiment of Figure 9 , the measurement unit 200 further includes a fourth probe 210d, a fifth probe 210e, and a sixth probe 210f for measuring the upper part of the measurement object O.

[0313] According to an embodiment, the fourth probe 210d, the fifth probe 210e, and the sixth probe 210f are arranged at positions spaced apart by a predetermined distance along the +Z axis direction with respect to the first probe 210a, the second probe 210b, and the third probe 210c described above, and are arranged at positions that simultaneously satisfy the above conditions 1 to 3. Thereby, the surface measurement device 1000 can simultaneously measure the upper and lower portions of the circumferential surface of the measurement object O, and thereby, the reliability of the surface measurement device can be improved.

[0314] According to an embodiment, the fourth probe 210d, the fifth probe 210e, and the sixth probe 210f may be arranged side by side with the first probe 210a, the second probe 210b, and the third probe 210c. According to an example, the fourth probe 210d may be on the same straight line as the first probe 210a along the Z axis direction, the fifth probe 210e may be on the same straight line as the second probe 210b along the Z axis direction, and the sixth probe 210f may be on the same straight line as the third probe 210c along the Z axis direction, but is not limited thereto.

[0315] Figure 16 A diagram showing a surface measurement device for an object according to a seventh embodiment of the present invention.

[0316] Refer to Figure 16 , different from the embodiment of Figure 15 , the measurement unit 200 further includes a seventh probe 210g and an eighth probe 210h for measuring the upper end of the measurement object O.

[0317] According to an embodiment, the measurement unit 200 further includes a seventh probe 210g and an eighth probe 210h arranged at one upper end of the measurement object O for detecting the upper end of the measurement object O. In this case, the seventh probe 210g may be on the same straight line as the rotation axis of the measurement object O, and the eighth probe 210h and the seventh probe 210g may be at the same height along the Z axis direction.

[0318] Figure 17 A diagram for explaining a method of measuring the shape of a surface measurement device for an object having a circular cross-sectional shape according to an embodiment of the present invention.

[0319] Refer to Figure 17 , different from the embodiment of Figure 16 , the above surface measurement device 1000 further includes a second support portion 150.

[0320] The support part 100 can be placed on the upper end of the flat plate 300, and the object to be measured O1 can be placed on the upper end of the support part 100. Moreover, the second support part 150 and the second object to be measured O2 can be successively placed on the upper end of the object to be measured O1. In other words, the support part 100, the object to be measured O1, the second support part 150, and the second object to be measured O2 can be placed in the above order on the upper surface of the flat plate 300 along the +Z axis direction. According to an embodiment, the centers of the second object to be measured O2 and the object to be measured O1 are located on the same straight line along the Z axis direction. According to an embodiment, the drive part can cause at least one of the support part 100 or the second support part 150 to perform a rotational motion (R).

[0321] According to an embodiment, the measurement part 200 further includes a fourth probe 210d, a fifth probe 210e, and a sixth probe 210f for measuring the outer periphery of the second support part 150. According to an embodiment, the fourth probe 210d, the fifth probe 210e, and the sixth probe 210f are arranged at positions spaced apart by a predetermined distance along the +Z axis direction with reference to the first probe 210a, the second probe 210b, and the third probe 210c, and are arranged at positions that simultaneously satisfy the above conditions 1 to 3. The fourth probe 210d, the fifth probe 210e, and the sixth probe 210f can be arranged side by side with the first probe 210a, the second probe 210b, and the third probe 210c. According to an example, the fourth probe 210d can be located on the same straight line as the first probe 210a along the Z axis direction, the fifth probe 210e can be located on the same straight line as the second probe 210b along the Z axis direction, and the sixth probe 210f can be located on the same straight line as the third probe 210c along the Z axis direction, but it is not limited thereto.

[0322] The measurement part 200 further includes a seventh probe 210g and an eighth probe 210h for measuring the bottom surface of the second support part 150. In this case, the seventh probe 210g and the eighth probe 210h can be located at the same height along the Z axis direction.

[0323] According to an embodiment, the measurement part 200 may further include a shape measurement probe 250. The shape measurement probe 250 can be located at a position spaced apart by a predetermined distance from one side surface of the second object to be measured O2, and can send a signal to the surface of the second object to be measured O2 that performs a relative rotational motion. Moreover, the shape measurement probe 250 receives the signal reflected from the surface of the second object to be measured O2 to generate a shape signal.

[0324] According to an embodiment, the above operation unit may sum up measurement signals derived from the measurement object O1 to generate a composite signal, and may derive a drive error signal related to the measurement object O1. At the same time, the above drive error signal derived through the above process may be subtracted from the drive error signal of the second measurement object O2. Thus, the surface measurement device 100 may derive accurate shape information of the second measurement object O2.

[0325] As described above, the present invention has been described in detail through preferred embodiments. The scope of the present invention is not limited to specific embodiments, but is interpreted by the appended claims of the invention. And, as long as those of ordinary skill in the technical field to which the present invention pertains, various modifications and variations can be made without departing from the scope of the present invention.

[0326] Industrial Applicability

[0327] The surface of an object can be accurately measured by using the surface measurement device and measurement method of the object according to the embodiments of the present invention.

Claims

1. A surface measurement device for an object, comprising: A support part for placing the object to be measured; At least three probes for measuring the surface of the object to be measured; A drive part for relatively rotating the support part and the at least three probes about the center of the object to be measured; and An arithmetic part for combining the measurement signals received by the at least three probes to generate a composite signal, and removing a drive error signal and a shape error signal of the object to be measured that occur during the relative rotational movement from the composite signal, Based on the center of the object to be measured, the at least three probes are located at positions where the angle between the probes is greater than 0 degrees and less than 180 degrees, The ratio of the angle between one probe and another probe among the at least three probes to the angle between the one probe and another probe among them is an irreducible fraction.

2. The surface measurement device for an object according to claim 1, wherein Based on the center of the object to be measured, the at least three probes are respectively arranged at non-opposite positions.

3. The surface measurement device for an object according to claim 1, wherein The arithmetic part obtains a signal in which harmonic components are linearly combined by performing a Fourier transform on the signal obtained by removing the drive error signal from the composite signal, The rotation device defines the total measurement range angle when the sampling angle Δ is rotated by the set signal reception number N as T, and the ratio of the total measurement range angle T to the angle between the one probe and the other probe is defined as the irreducible fraction a α / b α , the ratio of the total measurement range angle T to the angle between the one probe and the other probe is defined as the irreducible fraction a β / b β In the case of min The wavelength of the longest harmonic is λ max The ratio λ max / λ min The value is smaller than that in the above b α and b β The value of 1 is removed from the least common multiple {LCM (b α , b β )-1} and the ratio r of the total measurement range angle T for 360° rotation T =The product of T / 360°.

4. A surface measurement method for an object, comprising: A step of relatively rotating a support part for placing the object to be measured and at least three probes located on one side of the support part about the center of the object to be measured; A step of measuring the surface of the object to be measured among the at least three probes during the relative rotation to generate a measurement signal; A step of combining the measurement signals to generate a composite signal; A step of removing a drive error signal that occurs during the relative rotational movement from the composite signal; And A step of removing the shape error signal of the object to be measured from the composite signal after removing the drive error signal, The at least three probes are located at positions where the angle between them based on the center of the object to be measured is greater than 0 degrees and less than 180 degrees, The ratio of the angle between one probe and another probe among the at least three probes to the angle between the one probe and another probe among them is an irreducible fraction.

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