JPH0777408A - End section position measuring method for object - Google Patents

Abstract

PURPOSE:To measure the position of an end section with high measurement accuracy by radiating a laser beam to an object nearly perpendicularly, receiving the reflected beam, and measuring the distance between a radiation position and the object and the light quantity while moving the radiation position in parallel with the measured object. CONSTITUTION:An optical sensor 11 measures the distance to a measured object 10 and measures the reflected light quantity from the phase difference between a laser beam 111 continuously radiated nearly in the parallel direction with the surface of the measured object 10 and the reflected light by the measured object 10. When the surface of the measured object 10 is rough and not planar optically, even though planar physically, the radiated laser beam 111 is irregularly reflected, and the reflected light quantity received by the optical sensor 11 is largely fluctuated. To prevent erroneous measurement, the measurement position X1 obtained from the distance measurement and the measurement position X2 obtained from the reflected light quantity are acquired in parallel. When the condition ¦X1-X2¦<0.5mm is satisfied, the position of X2 is adopted. When the condition ¦X1-X2¦>=0.5mm is satisfied, the position of X2 is adopted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring the position of an end of an object, and more particularly to a method for measuring the position of the end of an object using an optical sensor.

[0002]

2. Description of the Related Art Conventionally, for measuring the position of an end portion for welding, there is a complicated measuring method using a CCD camera or the like, as disclosed in JP-A-3-207577. Further, the measurement of the end position of an object using a simple optical sensor is performed, for example, by setting a predetermined distance to the object to be measured, irradiating a laser to measure the distance, and measuring the object by a change in the measured distance. I was guessing the end.

FIG. 4 is a diagram showing the arrangement relationship between the object 10 to be measured and the optical sensor 11 as a distance measuring device (the relationship of arrangement is the same as the old and new), and FIG. 9 shows the relationship between the optical sensor 11 and the object 10 to be measured. The positional relationship is shown. X at the end of the DUT 10 is a measurement position to be obtained. When this position is measured using the optical sensor 11, the position of the end portion X1 is calculated from the sensing shape shown in FIG. In the graph of FIG. 10, there are a flat portion due to the flat portion 6a of the object and a flat portion 6b due to the non-reflecting portion with respect to the vertical axis Z, and the average measurement position Z1 of the flat portion 6a due to the flat portion of the object and the predetermined distance p change. The point X1 where the line at the position (Z1 + p) and the measurement shape line intersect is set as the end position.

[0004]

However, as shown in FIG.
As shown in, the measurement of the end of the measured object of the distance measuring device is insensitive, and even if the shape of the end of the measured object is not rounded, the shape of the measured graph is slightly sagging at the end. Will be in a state of Due to this slowing of measurement, ±
It is empirically known that an error of about 0.2 mm occurs.

It is an object of the present invention to provide an object edge position measuring method capable of measuring the edge position with high measurement accuracy.

[0006]

In order to achieve such an object, the object edge position measuring method for measuring the position of the edge part of an object of the present invention is to irradiate an object with a light beam at a substantially right angle and reflect it by the object. The light receiving step of receiving the received light, the distance measuring step of measuring the distance between the irradiation position of the light beam and the object by the light received by the light receiving step, and the reflected light amount of measuring the light quantity of the light received by the light receiving step The position X1 of the end portion of the object is determined from the measuring step, the moving step of moving the position of irradiating the light beam substantially parallel to the object, and the amount of change in which the distance measured by the distance measuring step changes depending on the position of the moving step. A first edge measuring step for measuring and a second edge measuring step for measuring the position X2 of the edge of the object from the amount of change in which the light quantity measured by the reflected light quantity measuring step changes depending on the position of the moving step. Have and measure Positions of the two ends X1 and position X2
The feature is that the final measurement position is obtained from and.

In the final measurement position described above, the measured positions X1 and X2 at the two ends are | X1-X2.
If there is a relationship of | <0.5 mm, then X2,
X has a relationship of | X1-X2 | ≧ 0.5 mm.
It is preferable that 1 is the final measurement position.

Further, in the second edge measuring step, in measuring the position X2 of the edge of the object, three kinds of predetermined light amount values A,
The values XA, XB, and XC of the positions corresponding to B and C (however, the relationship of the magnitude of the light amount is A>B> C) are measured, and the relationship between these three positions and the predetermined distance k is determined. , XC-X
When the relationship of A> k is satisfied, XC is set to X2, and XC-
When the relationship of XA> k is not satisfied, XB may be set to X2.

When the light quantity measured in the reflected light quantity measuring step does not reach the predetermined light quantity value A or the light quantity value B, X is determined by the position XC corresponding to the light quantity value C and the predetermined distance q.
2 is obtained in the relationship of X2 = XC + q, and the predetermined light amount value A may be an approximate value of the light amount reflected by the plane portion of the object.

[0010]

According to the object edge position measuring method of the present invention, the object is irradiated with the laser at a substantially right angle and the reflected light is received, and the irradiation position of the laser, the distance between the objects and the light quantity are measured with respect to the object to be measured. Move in parallel and measure as you lick. A predetermined change amount point of this measurement data is obtained and used as the end position. Therefore,
The measurement positions X1 and X2 of the end portion are obtained by two different methods based on the same laser irradiation, and the final measurement position can be determined from these two measurement results.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for measuring an end position of an object according to the present invention will be described in detail with reference to the accompanying drawings. 1 and 2, there is shown an embodiment of edge position measurement to which the object edge position measurement method of the present invention is applied. Hereinafter, the configuration of the present invention will be described in detail based on the embodiments shown in the drawings.

The measurement method is carried out by using the optical sensor 11 shown in FIG. 4, for example. The optical sensor 11 generally irradiates the measured object 10 with a laser 111 that modulates and modulates a laser beam, and the distance between the measured object 10 and the measured object 10 is determined by the phase difference between the laser reflected from the measured object 10 and the emitted laser. To measure. In the measurement of this method, the object to be measured 10 is further added.
The amount of received light reflected from is also measured.

Each example of the measurement result of the amount of reflected light from the measured object 10 (FIG. 1) and the measurement result of the distance to the measured object 10 (FIG. 2) in the measurement relationship of FIG. 4 is shown.

In the measurement result of the amount of light reflected from the object 10 to be measured by the optical sensor 11 shown in FIG. 1, the edge of the object 10 is sharply detected. FIG. 1 shows the amount of reflected light from the object to be measured 10.
Is the amount of light reflected by the ratio measurement object 10 and returned to the optical sensor 11. When the position of the end of the measured object 10 is measured by the laser 111, the change in the amount of reflected light allows the shape of the end to be captured more sharply than by measuring the distance. Therefore, it is more accurate to measure the position from the change in the amount of received light.

However, there are problems. For example, when the surface of the DUT 10 is rough, the amount of received light becomes unstable due to irregular reflection. Therefore, if the end portion is simply detected only by the amount of reflected light, erroneous measurement may occur. This relationship will be described below.

In the relationship between the optical sensor 11 and the object 10 to be measured in FIG. 4, two measurements of the distance between the optical sensor 11 and the object 10 and the amount of light reflected by the object 10 are measured. The measurement is continuously performed in a direction substantially parallel to the surface of the measurement object 10. The results obtained by this measurement are shown in the graph of FIG. 1, where the horizontal axis X is the position of the optical sensor 11 and the vertical axis Z is the amount of reflected light. The flat portion 1a having the larger amount of reflected light in FIG. 1 corresponds to the flat portion of the object to be measured 10, and the flat portion 1b having the smaller amount of reflected light represents the state in which there is no object 10 to be measured and there is no amount of reflected light. In the graph of FIG. 2, the horizontal axis X is the position of the optical sensor 11, and the vertical axis Z is the distance between the optical sensor 11 and the object to be measured 10. The flat portion 2a on the “−” side of the distance Z in FIG. 2 corresponds to the flat surface portion of the object 10 to be measured, and the flat portion 2b on the “+” side of the distance Z corresponds to a portion without the measured portion.

The graph of the amount of light reflected by the object shown in FIG. 1 shows the case where the surface of the object 10 to be measured is optically flat. If the surface of the object to be measured 10 is physically flat, such as rough, but is not optically flat, the irradiated laser 111 is diffusely reflected, and the amount of reflected light received by the optical sensor 11 is greatly disturbed. . FIG. 3 shows such a state, and is a graph showing an example of the measured value of the reflected light amount when the surface of the DUT 10 is rough. In the graph of FIG. 3, the amount of reflected light 3a from the flat portion of the object to be measured 10 is greatly disturbed, and when the end of the object to be measured 10 is measured from the end of the flat portion of the graph of the amount of reflected light, the detection end X2 ′. The point is markedly separated from the true end X0.

In the object edge position measuring method according to the present invention, the measuring position X1 obtained from the distance measurement and the measuring position X2 obtained from the reflected light amount in order to prevent erroneous measurement due to the above cause.
And are acquired in parallel, and the measurement position is decided by comparing both. The final measurement position is determined by the one measurement position X1 and the other measurement position X2 based on the following procedure.

If the condition of | X1-X2 | <0.5 mm is satisfied, the position of X2 is adopted.

When the condition of | X1−X2 | ≧ 0.5 mm is satisfied, the position of X1 is adopted.

This selection procedure is insensitive to edge detection,
Although a large erroneous measurement does not occur, one measurement value X1 is likely to include a small amount of measurement error, and the normal measurement is accurate because it is sensitive to the detection of the end portion, but a large error is included when the surface shape is special. This is to use the other possible measured value X2 to compensate for the mutual defects and to take advantage of the advantages.

According to the above measuring method, it is possible to measure the end portion of the object to be measured 10 with high accuracy by using the conventionally used optical sensor 11 and a simple measuring procedure. (Variation 1) It has already been described based on the graph of FIG. 3 that when the surface of the measured object 10 is rough, the amount of reflected light from the flat portion of the measured object 10 is greatly disturbed. An example of a procedure for obtaining a stable measurement result even with the disturbance of the reflected light amount will be described below.

FIG. 5 shows an example of measuring the amount of light reflected from the object 10 to be measured in FIG. This graph particularly illustrates the case where the amount of received light is unstablely measured at the end of the DUT 10.

In FIG. 5, the horizontal axis X represents the position in the direction parallel to the surface of the object 10 to be measured, and the vertical axis represents the amount of received light.
When the amount of light reflected from the surface of the object to be measured 10 is large and the amount of light received by the optical sensor 11 is normal, the amount of light received at the end of the object to be measured exhibits a sharp acute angle as indicated by the alternate long and short dash line 4b. This form corresponds to the graph of FIG. However, when the amount of reflected light is insufficient and is not stable, the form is as shown by the solid line 4a in FIG.

In the reflected light quantity measurement based on FIG. 5, 3
Different types of received light levels A, B, and C are provided. The received light amount level A is the reflected light amount of the flat portion 4a by the surface portion of the DUT 10. The received light amount level B is a level lower than the received light amount level A by a predetermined amount. The received light amount level C is lower than the received light amount level B by a predetermined amount. The positions on the X axis at the above three types of received light levels are respectively set to X.
A, XB, and XC. This position XB is the position X in FIG.
It corresponds to 1. Although the position XB corresponding to the position X1 is measured as the end of the DUT 10 in the above-described embodiment,
Since the erroneous measurement is likely to occur due to the disturbance of the amount of light received by the flat surface portion, the measurement of the end portion is performed by the following measurement procedure in this variation.

In the relationship among the above-mentioned three types of measurement positions XA, XB, and XC, the presence or absence of the following relationship is checked.

XC-XA> k, where the symbol k is a constant representing a predetermined distance, and 0.5 mm is adopted in this variation. When this condition is satisfied, the position of the end of the DUT 10 is measured as XC, and when the condition is not satisfied, the position is measured as XB.

According to the above procedure, many erroneous measurements due to the disturbance of the light receiving amount on the flat surface portion can be eliminated, and the edge portion of the object to be measured can be measured with higher accuracy. (Variation 2) Variation 2 relates to the measurement procedure when a sufficient amount of received light cannot be obtained as in Variation 1, and in particular, when a curved surface portion is provided at the end of the measured object. Applied to.

FIG. 8 shows a state in which the position of the end of the DUT 12 having a curved surface at the end is measured.
The state in which the laser 111 is irradiated to the end portion of 2 is conceptually shown. The object to be measured 12 in the state shown in FIG.
6 and 7 are graphs showing data examples of the received light amount obtained by measuring the end portions of the.

The horizontal axis in FIG. 6 is the position X in the direction substantially parallel to the surface of the object to be measured 12, and the vertical axis in FIG. 6A is Z.
The distance from the optical sensor 11 in the axial direction, and the vertical axis in FIG. 6B represents the amount of received light. The difference between FIG. 6 and FIG. 7 is that the surface portion of the DUT 12 is normal and a sufficient amount of reflected light is obtained, and FIG. 7 is that the surface portion of the DUT 12 is abnormal. This is the case where a sufficient amount of reflected light could not be obtained.

In this variation, two types of measurement procedure, i.e., a. Case of a sufficient amount of reflected light, and b. Example of a measuring procedure, in case of insufficient reflected light amount, will be described below.

In the measurement procedure B of the variation example, the position in the X-axis direction where the amount of received light in FIG. 6 (B) becomes the predetermined value D is XD, and the position separated from the position XD by a predetermined distance q1 is X6. And Therefore, the two positional relationships are X6 = XD
It becomes + q1. The position X6 obtained by this procedure is the end of the DUT 12. The predetermined distance q1 is the measured object 12
It is empirically determined based on the shape of the curved surface at the end of the, the measurement characteristics of the optical sensor 11, and the like.

The measurement procedure B of the modified example will be described below. In FIG. 7, the two figures, (A) and (B), are similar to the relationship in FIG. The position in the X-axis direction where the amount of received light in FIG. 7B has a predetermined value E lower than the above-described predetermined amount D is XE, and a position separated from the position XE by a predetermined distance q2 is X7. Therefore, the two positional relationships are X7 = XE
+ Q2. The position X7 obtained by this procedure is the end of the DUT 12.

The above two measurement procedures a and b are measurements at two points with different light reception amounts, and when a large light reception amount is obtained and the predetermined amount D is reached, the two measurement procedures a and b can be executed. Is. Positions X6 and X7, positions Z1 and Z2 of these two measurement results are theoretically X.
It is possible that 6 = X7 and Z1 = Z2. In actual measurement, it is recommended to select or use measurement procedure a and measurement procedure b together.

Further, the measurement procedure examples a and b of the modified example 2 have been described with respect to the object to be measured having the curved surface portion at the end, but this shows a case where it is relatively difficult to accurately measure the position of the end portion. It is a thing. Therefore, there is no problem in using a similar measurement procedure even when measuring an acute-angled end as shown in FIG.

The above embodiment is one example of the preferred embodiment of the present invention, but the present invention is not limited to this and various modifications can be made without departing from the gist of the present invention. For example, in the above embodiment, one sensor measures the distance and the amount of reflected light, but two sensors may be used.

[0037]

As is clear from the above description, the method for measuring the edge position of an object according to the present invention receives the reflected light of the laser applied to the object to be measured, and changes the distance of the object to be measured and the amount of reflected light. The position of the end is to be detected from the change amount of. These two different measurement methods have different characteristics,
It is possible to improve the measurement accuracy of the end position by separating and selectively adopting the obtained measurement position X1 and position X2.

[Brief description of drawings]

FIG. 1 is an example diagram showing a relationship between a distance Z and a lateral position X between an optical sensor, which is one measuring element of an object edge position measuring method of the present invention, and an object.

FIG. 2 is an example diagram showing the amount of light reflected by the surface of an object, which is another measurement element of the method for measuring the edge position of an object of the present invention, in relation to the lateral position X.

FIG. 3 is another example diagram of a relationship similar to that of FIG.

FIG. 4 is a conceptual diagram showing a positional relationship between an optical sensor and an object to be measured, for explaining the procedure of the method for measuring the edge position of an object of the present invention.

FIG. 5 is an example of a measurement graph of the amount of received light for explaining the first modification of the embodiment.

6A and 6B are views for explaining a second variation example A of the embodiment, where FIG. 6A is a distance Z with respect to the measurement position X, and FIG. 6B is measurement graph example 1 of the amount of received light with respect to the measurement position Z.

7A and 7B are diagrams for explaining B of the second modification of the embodiment, in which FIG. 7A is a distance Z with respect to the measurement position X, and FIG. 7B is a second measurement graph example 2 of the amount of received light with respect to the measurement position Z.

FIG. 8 is a conceptual diagram showing a relationship between an object to be measured and a laser for explaining the measurement procedure of the second modification.

FIG. 9 is a conceptual diagram showing a positional relationship between an object to be measured and a light beam sensor, for explaining a principle of measuring an end position of an object according to a conventional technique.

FIG. 10 is a diagram showing a relationship between a distance Z and a lateral position X between an object to be measured and a light beam sensor for explaining a principle of measuring an end position of the object according to a conventional technique.

[Explanation of symbols]

1a a relational graph between the amount of measured light reflected by the surface of the object to be measured and the lateral position, 1b a relational graph between the measured light amount and the lateral position of the portion without the object to be measured, 10, 12 the object to be measured, 11 optical sensors, 111 laser, X lateral position with respect to the surface of the measured object, Z distance in the beam direction.

Claims (5)

[Claims] 1. An object edge position measuring method for measuring an edge position of an object, the method comprising: receiving a light beam that illuminates the object at a substantially right angle and receives light reflected by the object. A step, a distance measuring step of measuring a distance between the irradiation position of the light beam and the object by the light received by the light receiving step, and a reflected light amount measuring step of measuring a light amount of the light received by the light receiving step. A moving step of moving a position of irradiating the light beam substantially parallel to the object, and a position of an end portion of the object based on a change amount in which the distance measured by the distance measuring step changes depending on the position of the moving step. A first edge measuring step of measuring X1, and a second edge measuring step of measuring the position X2 of the edge of the object from the amount of change in the light quantity measured in the reflected light quantity measuring step depending on the position of the moving step. And a final measurement position from the measured positions X1 and X2 of the two end portions. 2. The final measurement position is such that the measured positions X1 and X2 of the two ends are | X1-X2.
If there is a relationship of | <0.5 mm, then X2,
X has a relationship of | X1-X2 | ≧ 0.5 mm.
The end position measuring method for an object according to claim 1, wherein 1 is set as a final measurement position. 3. The second edge measuring step described above comprises three types of predetermined light quantity values A, B, C (however, the relationship between the magnitudes of the light quantity is used in the measurement of the position X2 of the edge of the object). A>B> C
The values XA, XB, and XC of the position corresponding to (3) are measured, and the relationship between these three positions and the predetermined distance k is
The XC is set to the X2 when the relation of XC-XA> k is satisfied, and the XB is set to the X2 when the relation of XC-XA> k is not satisfied. A method for measuring the edge position of the described object. 4. When the light quantity measured in the reflected light quantity measuring step does not reach the predetermined light quantity value A or the light quantity value B, the X2 is determined by the position XC corresponding to the light quantity value C and a predetermined distance q. 4. The method for measuring the edge position of an object according to claim 3, wherein X is calculated in the relationship of X2 = XC + q. 5. The method for measuring the edge position of an object according to claim 3, wherein the predetermined light amount value A is an approximate value of the amount of light reflected by the flat surface portion of the object.