JPS5927843B2 - Optical angle detection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is designed to improve the relationship between the work tool and the work surface in work that requires the work tool to be maintained at a fixed distance and in a fixed posture relative to the work surface, such as arc welding work and painting work. The present invention relates to a method for detecting distance and angle without contact.

Conventionally, a method of detecting the relative relationship between the work tool and the workpiece and a contact type, that is, a method of detecting the relative relationship by bringing the detector into contact with the workpiece (al), are known. It cannot be applied to work that requires movement or where contact is not permitted.

- On the other hand, as a non-contact type, a spot light is scanned by a mechanical scanning mechanism to illuminate the work surface, and the spot light (4) is received by an image sensor such as a videcon, photo 1, diode array, etc., and the spot light on the image receiving surface is There is a method of detecting the coordinates of the workpiece from the two-dimensional position of the image, but this requires a mechanical scanning mechanism and a two-dimensional image sensor, so it is difficult to miniaturize the device. I can't do it,
The present invention was developed in view of the above-mentioned circumstances; it is a non-contact type, has no moving parts, and has the disadvantage of being weak against vibrations. The object of the present invention is to provide an angle detection method that can be processed.

Hereinafter, the contents of the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a diagram illustrating the principle of the present invention, showing the relationship between an optical angle detection device comprising an image sensor 1 and a spot light source 2, and a work surface 3. As shown in FIG.

That is, the spots 4, 5, 6, and 7 on the workpiece surface 3 irradiated from the light source 2 form an image on the light receiving surface 12 of the image sensor 1, and by detecting the position of the image on the surface. , the angle formed by the image sensor 1 and the work surface 3 can be obtained. First, the positional relationship between the image sensor 1, the spot light source 2, and the diffusion angle of the spot light will be explained using FIG.

In FIG. 2, the X, Y, and Z axes are 1 of the image sensor 1.
It is a right-handed orthogonal coordinate axis with the nonzu center point 8 as the origin and the central optical axis 10 as the z-axis. Figure a is a Y--Z-/V plane projection view, and is an X-Y plane 1-hi projection view. , c are Z-X plane projection views. The spot light source 2 has its point light source 9 (assuming that the diffused spot light is an older brother from that point) on the Y axis
, 'f, Place the point 1. [The distance between points 8 and 9 is D, and the angle between the central axis 11 of the light source 2 and the z-axis is α.

In addition, the diffusion angle of the spot lights 4, 5, 6, and 7 from the point light source 9 is generally arbitrary as long as the spot lights fall within the field of view of the image sensor, but for the purpose of simplifying the explanation and calculation formula, In this embodiment, as shown in both the projection views of FIG.
-C with an angle of 1, γ2 is determined, and further, as shown in FIG. ,α,β
, γ1, and γ2, the relationship described below is established. That is,
The coordinates of spots 4, 5, 6, and 7 in the XYZ coordinate system are (Xi, yi, zi) (1-4, 5, 6, 7), respectively.
Then, the following two equations hold true from FIG. 2A and b. (1
), (2) and eliminate Yi, the following equation is obtained. X
．． iguI. : Ken-?・Tan (±γ1) (+F.i=4
，−〒? -7)}(3)XVzi=Tan(α+β)・
Tan (±γ2) (+: i=5, 1: i=6) Therefore, in Fig. 2c, the inclination of the optical axis with respect to the Yz plane is (
3), and the following (4
) If the formula holds true, then the likelihood axes of the sub-beam lights 4 and 5 or the optical axes of the spot lights 6 and 7 coincide in the X-Z plane projection, as shown in FIG. 2c. When the above formula (4) holds true, the second
As is clear from FIG.
Consider a plane consisting of V and H axes parallel to the Y axis, and express this as V - H plane) A: images 13, 14, 15, 16 of V
, H coordinates are (Hi, vi) (1:4, 5, 6, 7), and the Iz゛ lens coefficient of the image sensor is F, then (3
) in the equation is equal to Vi/F, so V
i is a constant expressed by the following formula. FIG. 3 shows the focal point of the image sensor, and as is clear from this, the spotlights 4, 5, 6, and 7 are focused on the image sensor surface expressed by equation (5). 2 straight lines 17.181 2 image 13,
14, 15, 16, two straight lines 17 in the V-H plane,
H coordinate Hi (1=4,5,6,7
) by measuring one-dimensionally, Subotto light 4, 5,
6 and 7 three-dimensional coordinates can be obtained.

The king dimension coordinates (Xi, yi, zi) can be easily obtained as follows based on the principle of king angle measurement. As shown in Figure 882b, spot lights 4, 5, 6, 7 and their images 1
Since 3, 14, 15, and 16 are in a point-symmetrical positional relationship with respect to the lens center point 8 of the image sensor, the following two equations hold true.

By eliminating Yi from equations (1) and (7), the following equation is obtained.

Furthermore, from equations (3), (4), (5), and (8), Xi can be obtained by the following equation.

Similarly, becomes.

In equations (8), (9), 00) above, the sign is i:5,
It is positive when it is 6, and negative when it is i: 4 and 7. Ichihi, (8
), (9), 00) Spot light obtained from equations 4, 5,
From the coordinates of three points among the three-dimensional coordinates 6 and 7, when the work surface is assumed to be a plane Mj, the equation of the plane is determined,
The inclination of the work surface in any direction with respect to the X-Y plane can be obtained.

Now, let the equation of the plane be Ax + By + Cz + d = O, and (Xi, yi, zi
)(1=4,56), the equation becomes as follows.

Therefore, from the equation (self), the inclination Gx in the X-axis direction and the inclination Gzo in the Yllllj direction of the X-Y plane, that is, the lens surface of the image sensor 1 and the work surface 3 in FIG. become.

C&t▼ Therefore, the inclination angle between the X-Y plane and the work surface in the X-axis and Y-axis directions is.

Also, the distance L between the -image sensor and the work surface is (
By setting x=y;0 in equation (4), it can be obtained. Figure 4 shows an example of application of the invention to arc welding.

In the figure, the image sensor 1 and the spot light source 2 are attached to a welding device 19 by a fixture 21 and move integrally with the welding device 19. At this time, the area 24 near the welding point 23 of the welding line 20-A is irradiated with, for example, four spot lights having fixed diffusion angles α, β, and r from the light source 2, and the spot image is displayed on the image sensor. 'f''1 is connected to the receiving plane. This spot image is converted into an electrical signal and output line 2
2 to a computer (not shown), the computer first calculates Hi (α, β, r are given as constants in advance), and then calculates (12) to (15) and (1
The tilt angle and distance between the surface 24 and the image sensor 1 are calculated using equation 6). Therefore, by comparing the calculated inclination angle and distance with predetermined values, the welding device 19
It is possible to control the posture of the workpiece so that it is always kept at a constant distance and perpendicular to the work surface 3. In this case, in order to eliminate the influence of arc light, it is conceivable to use a laser as the spot light source 2 and apply an optical bandpass filter to the image sensor 1. However, as the image sensor 1, an ITV camera, a line image sensor such as a photodiode array, or a CCD can be used. Furthermore, instead of the spot lights defined by the angles α, β, γ1, and γ2 described above, it is also possible to use two slit lights defined by similar angles β. As is clear from the above description, according to the present invention, the workpiece surface of the work tool can be
- The distance and angle information necessary to control the relative position of the light source can be detected using a one-dimensional image sensor and the light source does not have any moving parts. This has the effect of making it smaller and more solid.

[Brief explanation of the drawing]

Figure 1 is a diagram of the principle configuration of the present invention, Figure 2 is a projected view of Figure 1, Figure 3 is a view of the focal plane of the image sensor in Figure 1, and Figure 4 is a diagram of the focal plane of the image sensor in Figure 1.
The figure is a diagram showing an applied sequence of the present invention. 1... Image sensor, 2... Spot light source, 3...
... Work, 4, 5, 6, 7... spot.

Claims (1)

[Claims] 1. A plurality of three or more spot lights are irradiated on the work surface with a constant diffusion angle, and their images are connected to the focal plane of the image sensor, and the above-mentioned method is applied to changes in the relative positional relationship between the work surface and the image sensor. An optical angle detection method, comprising: calculating an inclination angle of the work surface with respect to an optical axis of the image sensor by detecting a change in position of a spot image on a focal plane of an image sensor.