JPH03160303A - Detecting method of multiple hole - Google Patents

Abstract

PURPOSE:To correctly detect the position of the center of each hole by a method comprising steps of irradiating slit beams intersecting through multiple holes, detecting three-dimensional coordinates of an end point of each hole, and determining the end point of each hole on the basis of the value of the coordinates. CONSTITUTION:A member 102 held by a working end 101 of an industrial robot 100 has a nut 106 fixed to a hole 104 formed in a flat plate 103. The nut 106 has a screw hole 105 of a smaller diameter than the hole 104. Slit beams 111 and 112 crossing at right angles to each other are irradiated to the member 102 from a slit beam source 110 in a manner to pass through the holes 104, 105. This is photographed by a second dimensional sensor 107 such as a television camera or the like, thereby to detect third dimensional coordinates of each of four end points A-D of the hole 104 and that of four end points E-H of the hole 105. In a processing circuit 109, the position of the center of each hole 104, 105 is operated and correctly detected on the basis of the value of the coordinates.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for detecting multiple holes concentrically in a member such as a mechanical part and whose diameter decreases stepwise in the axial direction.

In conventional technical mechanical parts, there is an N4 structure in which a nut is fixed concentrically facing the hole, and there is also a structure in which multiple holes are formed with decreasing radius in order in the axial direction. It becomes necessary to screw the bolt into the hole with the smallest diameter among the multiple step-shaped holes and insert the bottle through it. In the prior art, a member having such multiple holes is imaged by a two-dimensional sensor such as a television camera, and the hole with the smallest diameter located on the center side is detected.

Problems to be Solved by the Invention In such prior art, although the outline of the outermost hole is relatively easy to grasp and the center position of the outermost hole can be detected relatively easily, the outermost hole has a smaller diameter. Regarding the detection of inner holes, when the light is irradiated at an angle oblique to the axis of the multiple holes, the step-like peripheral shadow of the outer holes appears, making it difficult to capture the clear outline of the inner holes. Generally difficult. In addition, although multiple holes should be arranged concentrically, there is misalignment in the actual workpiece.
Even if the center of the outermost hole is detected, it does not match the center of the inner hole. Therefore, it was difficult with the prior art to accurately determine the center of the inner hole. An object of the present invention is to provide a method for detecting multiple holes that allows each hole in the multiple holes to be detected accurately.

Means for Solving the Problems The present invention provides a method for detecting multiple holes in a member having multiple holes concentrically shaped such that the diameter thereof decreases in steps in the axial direction. irradiate one surface of the multi-hole with mutually intersecting slit light, detect the three-dimensional coordinates of the end points of the slit light on the periphery of each hole, and determine the coordinates of each end point in the axis direction. This is a multiple hole detection method characterized by determining the end point of each hole. Further, the present invention is characterized in that the center position of each hole is calculated and determined based on the determined coordinates of the end point of each hole.

Effect According to the present invention, slit light is irradiated across each step-like hole of the multi-hole, and the slit light crosses each other, for example, in a cross shape, and thereby the periphery of each hole is irradiated. The three-dimensional coordinates of the end point of the slit light are detected by a three-dimensional sensor. 3 of the end points of each hole found in this way
By comparing the coordinate values in the axial direction, that is, the depth direction, of the multiple holes among the dimensional coordinates, it is possible to determine which hole each end point corresponds to. For example, when the axis of the three-dimensional sensor that images the end point of the slit light and the axis of the multiple hole are approximately parallel, the coordinate values of each edge of the multiple hole in the axial direction are approximately the same for each hole. Therefore, three end points that have almost the same value in the axial direction can be determined to be the end points of the same hole. Based on the coordinates of the end point of each hole determined in this way,
It can be found by calculating the center position of each hole. The slit light may be cross-shaped as described above, or may be T-shaped, or may have other shapes.

Embodiment FIG. 1 is a sectional view showing the configuration of an embodiment of the present invention.
A member 102 gripped by a working end 101 of an industrial robot 100 has a nut 106 concentrically attached to a hole 104 formed in a flat plate 103 and having a threaded hole 105 smaller in diameter than the hole 104 fixed by welding or the like. FIG. 2 is a front view showing this hole 104 and screw hole 105. Two-dimensional sensor 107 realized by a television camera, etc.
images the left surface of member 102 in FIG. The hole 104 and the threaded hole 105 constitute a multiple hole 108, and these holes 104 and 105 are concentric and step-shaped in the axial direction, and the diameter increases from the left to the right in FIG. It is shaped like a step to make it smaller. That is, the diameter of the screw hole 105 is smaller than the diameter of the hole 104.
The optical axis of the sensor 107 is, for example, approximately parallel to the axis of the multiple holes 108 in this embodiment. The output from the sensor 107 is given to a processing circuit 109 implemented by a microcomputer or the like. A slit light source 110 is arranged on the one surface side of the member 102, that is, on the side where the sensor 107 is arranged. This slit light source 110
, cross-shaped slit lights intersecting each other at 90 degrees are irradiated, and the state in which the slit lights are irradiated is shown in Fig. 3. The surface of the flat plate 103 is irradiated with a slit light 111 extending in * (vertical direction in FIG. 3), and
A slit light 112 extending laterally (in the left-right direction in FIG. The slit light 112 is irradiated on the nut 106 as shown by reference numerals 112a and 112b.The operation of the processing circuit 109 will be explained with reference to FIG.
0, the cross-shaped slit lights 111 and 112 are irradiated onto one surface of the member 102, and these slit lights 111
．． 112 crosses the multiple holes 108. When the slit beams 111, 112 do not hit the holes 104.1.05 and do not cross these holes 104, 105, the processing circuit 109 operates the robot 100 in step n3, so that the slit beams 11, 112 for the holes 104, 105
1.112 is detected by the sensor 107, the moving direction of the member 102 by the working end 101 of the robot 100 is determined, and the slit light 111.
A movement command signal is given, and the member 102 is moved by the robot 100 until it crosses the point 05.
In this way, the slit lights 111 and 112 are connected to the holes 104 and 105.
After crossing the hole 1, in step n4, each hole 1
The three-dimensional coordinates of four end points A to D of hole 104 and end points E to H of hole 105 are detected. In the coordinate system of this sensor l○7, the optical axis direction of the sensor 107 is the Z-axis direction, the direction perpendicular to the Z-axis direction in the first page is the Y-axis direction, and the direction perpendicular to the page of FIG. is the X-axis direction.

Therefore, in step n5, each end point A to D. Compare the coordinate values of E to H with each other.
The coordinate values of the end points A to D in the hole 104 of the flat plate 103 in the axial direction are the same or very similar. Also nut 10
The coordinate values of the end points E to H in the hole 105 of No. 6 are the same or very similar. Also, end points A to D and end point E
The coordinate values of ~H in the axial direction are shifted by the thickness t1 of the flat plate 103. Therefore, these end points A to D and end point E
By determining whether the coordinate values in the axial direction with ~H are the same or similar, the end points A-D of the hole 104 are determined.
and the end points E to H of the hole 105 can be determined. In step n6, the center position of each hole 104, 1.05 can be calculated and determined based on the coordinate values of the end points A to D and E to H obtained in this way. In this way, the center positions of the holes 104 and 105 can be detected accurately. 5rXi is a perspective view showing a configuration for three-dimensionally capturing multiple holes 108 by a 53-dimensional sensor 107. Although the following description will be made with particular reference to the hole 104, the same applies to the other hole 105 as well. A perfectly circular hole 104 is formed facing the flat surface of the member 102. This hole 104 is irradiated with a plurality of (two in this embodiment) slit lights. Note that the camera and the two floodlights 3.4 that emit slit light are integrated. The slit beams are planes respectively indicated by reference numerals 5.6. The optical cutting lines on the surface of member 102 are missing at holes 104, and their end points are indicated by reference numerals A, B, C, and D, respectively. The surface of the member 102 is
The image is captured by an industrial television camera 7. This camera 7 includes an imaging surface 8 of a charge storage device (abbreviated as CCD) and a lens 9 that images the surface of the member 102 on the imaging surface 8 .

The three-dimensional coordinate system of the member 102 is indicated by X, Y, Z, and the camera coordinate system of the camera 7 (coordinate system set on the imaging surface of the CCD) is indicated by Xc, Yc. The output from the camera 7 is given to a processing circuit 10. FIG. 6 is a block diagram showing the electrical configuration of sensor 107 shown in FIG. The floodlight 3.4 is a drive circuit 11
．． 12. A television camera control 13 included in the processing circuit 10 provides a synchronization signal to the charge storage element of the camera 7 via line l4, so that the video signal obtained from the charge storage element is transferred to line 15.
Analog/digital conversion circuit 1 of processing circuit 10 via
6 and converted to a digital value. The output from the analog/digital conversion circuit 16 obtained in this way has a threshold value which is a discrimination level from the threshold value setter 17, and
After comparison in comparator l8, a binarized signal is obtained from line 19. This binary signal is stored in the frame memory 20. The contents of the memory 20 are provided to the processing means 22 via the bus 21, and data can be transferred to an external processing circuit 109 via the communication controller 23. In one embodiment of the present invention having such a basic structure, first, the center position of the hole 104 is measured (chapters I to II to be described later), and then the inclination of the plane surface of the member 102 is measured. That is, the attitude angle is measured (Chapter 2 described later), and the distance between one surface of the member 102 and the camera 7 is measured (Chapter 2 described later). First, the principle of measuring the center position of the circle of the hole 104 will be explained. In the processing circuit 10, from step u1 to step u in FIG.
2, pass the two intersecting slit lights 5.6 through the hole 1.
04, and measure the three-dimensional positions of four end points A, B, C, and D missing at the edge of the hole 104.

1. Method for measuring three-dimensional positions of points A, B, C, and D using slit light 5.6.

A slit light projector 3 and a camera 7 are arranged as shown in FIG.
are the coordinates of the above-mentioned A, B, C, and D) in the object coordinate system as (x, yZ〉), and the coordinates of the image of point P on the imaging surface 8 as Q ( in the camera coordinate system). Xc, Yc).The perspective transformation of the camera 7 is shown in the first equation.The equation of the slit light plane 5 is shown in the second equation 6a*X
+b*Y+Z=d ・++ (
2) Therefore, the coordinates (x, Y
, Z) can be found by solving the first and second equations simultaneously. Basically, the three-dimensional coordinates of all points on the slit light planes 5 and 6 can be determined. Before solving the simultaneous equations consisting of the first and second equations, the coefficient (
CI1 to C34, h, a, b, d) are determined in advance.

The method is shown below. (1) Regarding calibration of camera parameters. CIl~C,l4 in the first equation are called camera parameters. The camera parameters are values determined depending on the focal length of the lens 9, the position of the principal point of the lens 9, the distance between the lens 9 and the light-receiving surface, that is, the imaging surface 8, and the like. Since it is difficult to actually measure these values, we obtain them using the following method. Expanding the first equation and eliminating the coefficient h, we get C1 1 x
+c1 2 pieces y+c1 ) book Z + CI 4-C31 book Xc * X-Csz * Xc * Y-C * x book Xc * Z-Cs
<DC= 0...(3-1) C2+ Car X+C22 Y+C2s'lZ+c24-C
Il*Xc*X-C=2 cars Xc*Y-C33*Xc*Z
-4 Cl Xc=0...(3-2) Therefore, the known 3 points of 6 points that are not on the same plane
The dimensional coordinates and the corresponding camera coordinates are shown in 3-1.
By substituting into Equation and Equation 3-2 and solving the 12-element simultaneous equations, the 12 unknowns (C + + ~ C.4)
is found. Here, in order to improve the accuracy of camera parameter calculation, we measure n points (n>6) whose three-dimensional coordinates are known and calculate them using the least squares method. From the third equation, the following 12 elements 2 for the coefficients CIl~C)4
A zero simultaneous equation is obtained. E*G=F...(
4)? = [Xc. Yc.・・・・・・・・・・・・・・・
......XClIYC,l]t...(6〉G
= [C. CI2 Cps Cl4 C21 C2■C
23 C2- C3, C32 C33] '...
・(7-1) However, C3-=1...
(7-2) G= (Et*E) −'*Et*F by least squares method
...By calculating (8>), G is found. (2) Calculating the coefficients of the equation of the plane of the slit light. Substituting the three-dimensional positions of the known three points on the plane of the slit light into the second equation , a, b, and d are obtained, and by solving this, a, b, and d can be calculated.Here, to increase the accuracy, we will calculate the three-dimensional coordinates of known n points (n>3>). Substitute into the second equation and solve the following three-dimensional n simultaneous equations using the method of least squares.
...(10), K= (J'* J) -' * Jt* l,
...determined from (11). (3) Calculation of three-dimensional coordinates of feature points. C. using the method described above. ~C34. Once a, b, and d have been determined, the three-dimensional coordinates of the feature point can be determined by combining the second and third equations and solving the following equation.

M*N=R...<12) However, N=[X Y Z]'
...<14) R=[C+4C3<*Xc
C24 C34*Vc d]t・=(15-1
) However, C34=1...
(15-2) From the 12th formula, N=M minus *R...(
l6〉■, How to measure the center of a circle passing through points A, B, C, and D.

The center of the circle that passes through points A, B, C, and D is on the plane that passes through the four points A, B, C, and D. (2a> The distances from each point A, B, C, and D are equal. It is found from the two conditions 1a and 2a. (1) Member 1
A plane P13 containing four points A, B, and CD, which is the surface of 02,
That is, calculation of the coefficients of the equation on the paper in FIG. 9 (step u3 in FIG. 7). Since the normal vector component of a plane including the four points A, B, C, and D has a large Z component and a small X and Y component and a small distance, the equation of the plane is expressed by the following equation.

a+*X+b+'k3/+Z=d+
++ (17) Since the four points A, B, C, and D are points on this plane, we can calculate a, b, and d using the least squares method, or we can also calculate the three points A, B, and C. In this case, a l + b l + d l is calculated using the inverse matrix, ignoring the precepts in the first row. (2) Calculation of the coefficients of the equation of a plane with equal distances from two points A, B, C, and D. Points (x, y, z) that are the same distance from each point can be expressed by the following formula. (x-x+) ”+ (y-y+) ”+ (z-zt
) 2=S − (19) (i=1 to 4) In order to calculate with high accuracy, two points with a large distance from each other are used for calculation. Here, we use bears at points A and B and points C and D. Referring to the plan view of FIG. 9, points at equal distances from points A and B are determined by the following equation (step u4 in FIG. 7).

-2*Xl *X+Xl"-2*y+ *l'+7+2
-2*z1*Z+Zl"=-2*X2*X+X2"-2
*g*y+y22-2*z2*z10z22
・・− (20−1)2(x+x2) *κ+20
'+y2)*y+2(z,-z2)Lz=(X+2
X2") + (y+'y2') + (21"-22")
- (20-2) This equation 20-2, a2*x+bz*3/10C2*z=d2
-・<20-3). Formula 20-3 is
This is the formula for the plane Pll. Points C and D are calculated in the same way (step u5 in Figure 7). 2(xt-x<)*x+2(ys-y<)*3/+2
(Z3-Z.) * Z=(Xs” x<2)+(y32
3'42) + (Z32Z42〉-(21-1)) a3*x b, *y+(3*z=di
...Set it as (21-2). Equation 21-2 is an equation for the plane P12.

(3) Calculation of the center O of the circle. The intersection of the three planes of Equation 17, Equation 20-3, and Equation 21-2 is the center of the circle. Therefore, the center coordinates of the circle (xcl
, yel. zcl) is found by solving the following simultaneous equations (step U6 in FIG. 7).

From this, ■, the attitude angle α around the X axis and the attitude angle β around the Y axis of the plane P13 are measured.

In FIG. 10 (1), when the plane P13a is angularly displaced by +Δα around the X axis and assumes the attitude of the plane P13b, the light cutting line 26 on the plane P13a of the slit light 5 is the light cutting line 26 on the plane P13b. As shown in line 27. On the imaging plane 8 of the camera 7, the image of the optical section line 26 with α=O is indicated by reference numeral 26a, and the image of the optical section line 27 after its rotation is indicated by reference numeral 27a. Further, as shown in FIG. 11(1), when the plane P13c is angularly displaced by the angle Δβ around the Y axis and becomes the plane P13d, the plane P13c
The upper optical section line 28 becomes an optical section line 29 on the plane P13d. Therefore, on the imaging surface 8 of the camera 7, the image 28a of the light section line 28 becomes an image 29a of two light section lines. In this way, the image 27a on the imaging surface 8. 29a, the plane P1
3a, P13b mutual angle Δα and planes P13c, P1
It can be found by calculating the angle Δβ of 3d. 1st
0 and 11, Δα. The definition of Δβ will be shown, and the method for determining the inclination of the plane will be specifically described with reference to FIGS. 12 to 14. (1) Attitude angle α around the X-axis of the target plane P13 shown in FIG. 13 and its target plane P1
In order to find the attitude angle β around the Y-axis of 3, first
Optical cutting line 30 of horizontal slit light on imaging surface 8 of camera 7
The equation of the light section line 30 is calculated in advance, and the equation of the light section line 30 is calculated in advance. The previously stored camera parameter CI
From l to C34, ■ Find the equation of the plane P14 passing through the light section line 30 and the principal point of the lens 9 (steps ml and m2 in Figure 12), and Find the equation of the plane P15 of the slit light in advance. (Step m3 in Figure 12). (2) Equations shown in the previous bar graph (1)■,■,■
And, depending on the camera parameters ■, the plane? 14,P1
Find the normal vector of each plane of 1. = (1. L, us)
−” (24), then l, and Pa, P's are orthogonal, so P2-14=O
...(25) P3・14=0
...(26) From this, e is found (step m4 in FIG. 12). (3) Similarly, from FIG. P17
If you also find the equation, the normal vectors of the planes P16 and Pl7 are Ps and Pt, respectively, and the direction vector of the intersection line 33 is 11=<5m. 1, ul)
”・(27) Toshide, P11m=0 ・・・(
28) P1・Is20
...(29) As a result, l. is required (12th
Step m7) in the figure. In FIG. 14, a plane P16 is a plane passing through the principal point of the lens 9, and P17 is a plane formed by the slit light of the projector 3.

(4) Normal vector Po of target surface P13 = (so. jo+ 1 >
-(30) is l 4+ 1 . Since it is orthogonal to , P0・14=0...
(31) P6-1. =O
-(32) As a result, P. is required (12th
Step m8) in the figure. Attitude angle α(X
The angle of rotation around the axis) and β (the angle of rotation around the Y axis) can be found using the following formula (step m9 in Figure 12).
...(33) β-jan-' (so)
- (34)
■, How to measure distance.

As shown in FIG. 15, when measuring the distance between the plane P13e and the imaging surface 8 of the force camera 7, this plane P13e
is displaced in a detectable range as shown by P13f and P13g, on the imaging surface 8, as shown in FIG.
35 and 36 are detected as images 34a, 35a, and 36a. In this way, the images 34a, 35a,
36a, planes P13e, P13
The distance between f and P13g can be measured. This method will be explained in more detail with reference to FIGS. 16 and 17. (1) The equation of the optical axis of camera 7 is x=y=0...(
35), and the distance d between the imaging plane 8 and the object plane P13 is defined as the Z coordinate of the intersection of the optical axis of the lens 9 of the camera 7 and the object plane P13. If the coordinates of one point on the target plane P13 are found, the target plane P13
The equation of the plane of the target surface P13 can be determined from the normal vector of . The point is obtained as the intersection of planes P14P15 and P17, and the point is expressed as (Xo, 3'o, Zo)
Then, the equation of the target plane P13 is 5. (X XO) +to (y-yo) + 1・(
z zo)=0...(36>) (step rl.r2 in Figure 16).(2) The distance ld is d=soXotoYo+Zo'
"' (37) (Steps r3 and r4 in FIG. 16). ① Measurement of surface position.

Referring to FIG. 18, in measuring the position of surface 13,
A slit light 6 is emitted from a single light projector 4, and a camera 7
It is assumed that the optical axis 37 of is perpendicular to the X-Y plane of the object coordinate system. At this time, one point and three three-dimensional positions on the intersection line 38 of the plane P13 to be measured and the slit light plane 6 are measured, and the Z-axis precept is defined as the surface position {that is, the height}.
The present invention can not only measure the center position of the hole 104, but also calculate the area of the hole 104 and other physical quantities widely, and such modifications are easy for those skilled in the art. ．． As another embodiment of the present invention, three or more holes 104, 105 may be formed so that the diameter thereof decreases sequentially in the axial direction. Effects of the Invention As described above, according to the present invention, mutually intersecting slit light that crosses the multiple holes is irradiated onto the surface facing the step-like holes of a member having multiple holes, and the periphery of each hole is The three-dimensional coordinates of the end point of the slit light are detected, and the end point of each hole is determined based on the coordinate value of the end point in the axial direction, making it easy to detect each hole that makes up the multiple holes. You will be able to do this quickly and reliably.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the overall configuration of an embodiment of the present invention;
FIG. 2 shows the front view of the member 102 as seen from the sensor 107 side.
FIG. 3 shows a slit light source 11 inserted into the multiple holes 108 of the member 102.
4 is a flowchart for explaining the operation of the processing circuit 109, and FIG. 5 is a simplified view of the three-dimensional sensor 107 according to an embodiment of the present invention. 6 is a block diagram showing the electrical IT of the three-dimensional sensor 107 shown in FIG. 5, FIG. 7 is a flowchart showing the procedure for calculating the center position of the hole 104, and FIG. FIG. 9 is a plan view of the plane P13, FIG. 10 is a diagram showing the definition of the attitude angle α of the plane,
Figure 1 is a simplified diagram showing the definition of the plane attitude angle β.
FIG. 2 is a flowchart showing the procedure for measuring the attitude angles α and β, and FIGS. 13 and 14 show a method for measuring the attitude angle α around the X axis and the attitude angle β around Ylill of the target plane P13. The simplified diagram, FIG. 15, is the plane P13.
A simplified diagram showing the principle of measuring the distances e, P13f, and P13g, FIG. 16 is a flowchart showing the procedure for calculating the distance d on a plane, and FIG. 17 is a simplified diagram showing the ellipse for measuring the distance d. The figure shown in FIG. 18 is a simplified diagram showing the principle of measuring the position of the surface 13 according to still another embodiment of the present invention. 100...Robot, 102...Member, 107...
・Two-dimensional sensor, 108...Multiple holes, 109...Processing circuit, 111.112...Slit light, A to D, E
~H...End point

Claims (2)

[Claims] (1) In a method for detecting multiple holes in a member having multiple holes formed concentrically and with diameters decreasing stepwise in the axial direction, one surface of the member having multiple holes is provided with a hole that crosses the multiple holes. The method involves emitting mutually intersecting slit lights, detecting the three-dimensional coordinates of the end points of the slit lights on the periphery of each hole, and determining the end points of each hole based on the coordinate values of the end points in the axial direction. Characteristic method for detecting multiple holes. (2) The method for detecting multiple holes according to claim 1, characterized in that the center position of each hole is calculated and determined based on the determined coordinates of the end point of each hole.