JP2519187B2 - Through-hole three-dimensional position measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a measurement point located in a space, for example, a tertiary position from a measurement point of a through hole which is a measurement point to be punched in a steel plate which is an object to be measured. This relates to a measuring device that measures the original position.

More specifically, the measurement position is set in advance in the assembly line, the three-dimensional positional relationship between the measurement position and the measuring device is obtained in advance, and the assembly line or the like is drilled on a moving steel plate, an automobile body, or another object to be measured. The present invention relates to a three-dimensional position measuring device that determines the suitability of a measuring point on an object to be measured by measuring the three-dimensional position of the measuring point such as an established hole with respect to the measuring device from a location distant from the object to be measured.

(B) Conventional Technology Conventionally, a measuring device shown in FIG. 6 is known as a three-dimensional position device for measuring a three-dimensional position for determining suitability of a measured portion provided on a measured object such as a steel plate. Has been.

In this conventional example, a through hole (1
02), X-axis pin (10
3) a, a Y-axis pin (103) b for measuring the Y-axis direction, a Z-axis pin (103) c for measuring the Z-axis direction, and a movable pin (104) inserted into the through hole (102).

That is, the movable pin (104) is previously set at a desired reference through hole position, and the X-axis pin (103) a, the Y-axis pin (103) b,
The tip of the Z-axis pin (103) c is brought into contact with the surface of the movable pin (104). This state is defined as the 0 position on each axis pin. Then, the movable pin (104) is inserted into the through hole (102). Then, although the movable pin (104) is moved depending on the installation position of the through hole (102), the contact sensor (105) a, (105) b, (105) c composed of the respective axial pins moves in the positive or negative direction. The information sensed as a moving direction and a moving amount is transmitted as a signal. Direction of movement,
Each of the determination units (106) a, (106) b, which have received the movement amount signal,
In (106) c, a reference signal generating section (107) for transmitting an information signal of a desired relational reference through hole position in each axial direction.
It also receives the reference signals from a, (107) b, and (107) c.

Judgment units (106) a, (106) b, (106) c respectively compare the two signals to judge whether or not the movement amount is within the error range of the reference through hole, and the display unit (108) indicates whether or not it is appropriate. indicate. At this time, since the three-dimensional relationship between the measuring device and the measurement position of the object to be measured is obtained in advance, the displayed suitability indicates the suitability of the position of the through hole (102) formed in the object to be measured. It will be.

(C) Problems to be Solved by the Invention However, the conventional measuring device has a problem in that the accuracy is deteriorated due to a phenomenon such as hole shape and pin wear because it is a contact type with four pins. Further, since it is a contact type, when measuring an object to be measured moving on a line, there is a problem that the stop time becomes long because the object to be measured is stopped from moving to make contact.

(D) Means for Solving Problems The present invention relates to an illumination means for projecting light onto the surface of an object to be measured, and an object to be measured with respect to the illumination means when the object to be measured having a through hole is installed at a measurement position. Reflection that is located on the opposite side across the background and is relatively dark compared to the reflected light that reflects the illumination from the illumination means on the surface of the object to be measured and the surface of the object to be processed that is installed toward the through hole surface The light receiving means for detecting light and generating a signal according to the light and darkness to be sensed, and the light receiving means are installed at an angle with respect to the through hole and sense the reflected light reflected on the surface of the workpiece and respond to the light and darkness to be sensed. An auxiliary light receiving means for generating a signal, a two-dimensional discriminating means for comparing a desired reference through hole image with a through hole image sensed by the light receiving means as a dark part of the background passing through the through hole without generating reflected light, Sensing as a dark area by the light receiving means and auxiliary light receiving means Computation means for computing a difference by comparing known through-hole images, and through-holes obtained by both light-receiving means when a difference between both through-hole images computed by the computing means and a desired reference through-hole image are measured A through-hole characterized by comprising a one-dimensional discriminating means for obtaining a difference between a desired distance between the reference through-hole and the light-receiving means and a distance between the through-hole and the light-receiving means by comparing image differences. By providing a three-dimensional position measuring device, the measuring time required for the pin-based measuring device is shortened and the measurement accuracy is improved. (E) Function The illumination means projects light onto the surface of the measured object. To do. Then, reflected light is generated in a portion other than the portion where the through hole is formed on the surface of the object to be measured, the through hole portion is represented as a dark portion of the background, and the light receiving means perceives the through hole and the periphery of the through hole as a difference in brightness.

The brightness difference detected by the light receiving means is transmitted to the two-dimensional discrimination means as a signal, but the dark portion detected by the light receiving means represents a through-hole image, and the two-dimensional discrimination means indicates a through-hole image. Will be received. The two-dimensional discriminating means also receives the reference signal from the reference signal generating means for storing the reference through-hole image information when the information from the desired reference through-hole is sensed by the light receiving means. The two-dimensional discriminating means compares the signal representing the actually measured two-dimensional through-hole image with the reference signal representing the two-dimensional reference through-hole information.

When the auxiliary light receiving means is provided, the distance between the through hole and the measuring device is calculated as follows. That is, the light receiving means and the auxiliary light receiving means are installed at an angle to the through hole.
Therefore, it is assumed that the dark portion of the through hole, that is, the through hole image, sensed by each light receiving means has different input information such as the position of the center of gravity or the area of the through hole image by the angle formed between each light receiving means and the through hole. Is perceived.

If the distance between the light receiving means and the auxiliary light receiving means is constant,
When the positions of the light receiving means and the through hole change, the angle formed by the light receiving means, the through hole and the auxiliary light receiving means changes. If this angle changes, the shape such as the inner diameter and area of the through hole image sensed by each light receiving means changes. Therefore, receiving each through hole image sensed as a dark part by the light receiving means and the auxiliary light receiving means,
The calculation means calculates the area difference or the difference in the inner diameter of the through hole image to calculate the horizontal distance between the through hole drilling surface and the center of gravity of the light receiving means.
The area or inner diameter is compared with the horizontal reference distance between the light receiving means and the through hole drilling surface obtained from the through hole images sensed by both light receiving means when the desired reference through hole is formed.

Therefore, the three-dimensional position of the through hole to be measured with respect to the light receiving means and the measuring device is compared with the desired three-dimensional position of the reference through hole.

(F) Embodiment An explanation will be given according to FIG. 1 showing an embodiment of the present invention and FIG. 2 showing the same usage state.

(11) is the measured object. The object to be measured (11) in this embodiment is an automobile monocoque body formed by processing unpainted steel plate on the automobile assembly line (12).

The object to be measured (11) is provided with a through hole (13) for attaching another component in the preceding step of measuring the through hole.

(14) is a factory facility inside which an automobile assembly line (12) is installed, and (15) is a lighting window installed in the factory facility. (16)
Is a light-shielding plate, which shields the natural light directly applied to the background (17) of the object (11) to be measured. The background (17) consists of the inside of the opposite side of the car body in this example.

(18) is a lighting means. In this embodiment, as the illuminating means, spot illumination having a high degree of condensing is used, and 75 W, and a halogen lamp, a tungsten lamp, or the like, which has a measurement surface of 1000 lx, is used. It is desirable that the illumination means (18) has a stable light quantity.

(19) is a light receiving means. The light receiving means (19) is installed on the same side as the measurement light source with respect to the DUT (11), and converts the inputted optical information into an electric signal. The light receiving means (19) is
In this embodiment, it consists of a CCD camera. A telephoto lens (19) a of about 300 mmf4 capable of obtaining a desired focal length and visual field range is fixed to the object (11) side of the light receiving means (19).
By attaching a telephoto lens (19) a, the light receiving means (19)
The depth of field becomes shallow and the amount of received light is extremely reduced in the out-of-focus portion. In this example, the DUT (1
1) The surface and the background (17) are provided with a distance of about 1000 mm, but they may be separated by a depth of field of 0.75 mm or more. The light receiving means (19) is installed toward the through hole (13).

Reference numeral (20) denotes an auxiliary light receiving means, which is a CCD camera like the light receiving means (19). (20) a is a similar telephoto lens. A straight line connecting the light receiving means (19) and the through hole (13) and a straight line connecting the auxiliary light receiving means (20) and the through hole (13) form an angle θ as shown in FIG. Install means (20). In this embodiment, when an object to be measured (11) having a reference through hole having a desired three-dimensional shape and area is installed at the measurement position, θ = 45 ° with respect to the reference through hole.
To be installed.

Image processing units (23) a and (23) b receive signals input from the light receiving unit (19) and the auxiliary light receiving unit (20), perform image processing, and display the images on a display unit (24) including a CRT screen. The through hole image (A) is displayed. (21) is a two-dimensional discriminating means, which receives signals from the light receiving means (19) and the image processing means (23) a. Reference numeral (22) is a reference signal generating means for displaying reference through-hole information such as the shape, area, position and center of gravity of the reference through-hole image obtained when a desired reference through-hole is detected at the position of the light receiving means (19). It is stored and transmitted to the two-dimensional discriminating means (21).

By the way, in the case of storing information on the shape and area, it is necessary to increase the capacity of the storage element in order to store the information for each pixel. The capacitance of the element may be small. Therefore, in this embodiment, the inputted information on the shape and area is calculated and stored as information on the point of the center of gravity.

(25) is a calculation means, which is an image processing means (23) a,
(23) b is connected to the light receiving means (19) and the auxiliary light receiving means (20).

(26) is a one-dimensional discriminating means, which is connected to the calculating means (25). (27) is a horizontal surface position signal generating means for the horizontal distance between the reference through hole drilled surface and the light receiving means, and the horizontal surface position signal generating means (27) is a measurement target having a desired reference through hole. When the object (11) is installed at the measuring position, the light receiving means (19) and the auxiliary light receiving means (20) are used to calculate the difference between the inner diameters of the through hole images sensed by the reference through hole drilling surface and the light receiving means. The horizontal distance is also transmitted to the calculation means as a signal.

The operation of the embodiment of the present invention will be described. First, light is projected from the illumination means (18) to the place where the through hole (13) is formed in the object to be measured (11) and its surroundings. The amount of light is 1000 even on the surface to be measured
lx, which is lower than the high-concentration halogen lamp of 3000lx, 500w on the surface to be measured that is generally used as a conventional reflection type two-dimensional measuring device, so when the work piece is made of high-brightness material such as steel plate. Even if there is, the reflected light again has scratches, dents,
Even if there is deformation or surface inclination, the sensitive change in luminance due to such deformation is reduced.

The light intensity of the measurement light source (18) is lower than that of the conventional example, while the background side of the DUT (11) does not have to be a special dark room and blocks only the direct light entering the background (17) out of natural light. It is only shielded from light by the plate (16). Therefore, from the position of the light receiving means (19), the periphery of the through hole that reflects the illuminating means (18) and the background appear as they are, so the difference in brightness between the through hole (13) portion appearing as a dark part is smaller than that of the conventional example. .

However, the light receiving means (19) has a telephoto lens (19) a, which has a shallow depth of field and whose amount of light received is extremely reduced in a portion out of focus, and also has a background (17). The distance between the surface of the object to be measured (11) and the surface of the object to be measured (11) is such that the amount of received light is extremely reduced when the surface of the object to be measured (11) is in focus. It matches the surface of the through hole (13) of the DUT (11). Therefore, the lightness difference between the periphery of the through hole (13) of the object to be measured (11) and the background (17) passing through the through hole (13) is emphasized as compared with the case where a standard lens is used. Detect in 19).

Therefore, the outline of the through hole (13) is received in a clear form, that is, the outline of the image of the through hole (13) is received. Also, since the depth of field is shallow, there is little influence on the captured image even if a small amount of natural light enters, except when direct light enters the light receiving means (19) between the background (17) and the DUT (11). .

The optical information received by the CCD camera of the light receiving means (19) is converted into an electric signal and sent to the image processing section (23) a. The signal received by the image processing section (23) a is subjected to image processing and transmitted as an image signal to the display section (24), where it is displayed as a through hole image (A). Similarly, the through hole image (B) sensed by the auxiliary light receiving means (20) is also displayed. The signal from the image processing section (23) a is also received by the two-dimensional discriminating means (21) at the same time.

The received through-hole image information is compared with the desired reference through-hole information signal transmitted from the reference signal generating means (22) in terms of shape, center of gravity position, and area, and it is judged whether or not it is within a two-dimensional allowable range. The suitability of the through hole is displayed on the display unit as suitability display (C).

In this embodiment, the difference between the center-of-gravity positions of the reference through-hole image and the measured through-hole image is compared to determine the suitability. When the suitability of the formed through-hole is judged by comparing the positions of the centers of gravity of the through-hole images as in this embodiment, the center of gravity O of the desired reference through-hole image (A) 'is determined as shown in FIG. ′ And the measured position of the through hole image (A) with respect to the center of gravity O are within the error range.

The through hole image information signal sensed by the light receiving means (19) is also received by the computing means (25) via the image processing means (23) a. The calculation means (25) is sensed by the auxiliary light receiving means (20) at the same time, is transmitted to the display means (24) through the image processing means (23) b, and is displayed as a through hole image information (B). Also receive. The computing means (25) compares the shapes of the through-hole images sensed by both light receiving means and finds the difference. Since the auxiliary light receiving means (20) is installed at an angle to the light receiving means (19) as shown in FIG. 1, the through hole image sensed by the light receiving means (19) and the auxiliary light receiving means (20) are detected. ) Is different from the image of the through-hole detected by.

The calculation result is sent as a signal to the one-dimensional discriminating means (26). The one-dimensional discriminating means (26) is also connected to the horizontal plane position reference signal generating means (27) for storing the horizontal plane position in the desired reference through hole image and transmitting it as a signal.
The reference distance signal received from the horizontal surface position reference signal generating means (27) is compared with the actually measured surface position.

The difference between the surface positions is compared, and it is judged whether or not it is within an error range, and the suitability of the through hole is displayed on the display unit as a suitability display (D).

Even if the light receiving means (19) is not installed directly on the through hole (13), the object (11) having the desired through hole is measured at the measurement position, and the desired through hole is obtained based on the through hole information. Information may be set and input to the reference signal generating means (22) and (27).

Embodiment I The arithmetic means of the embodiment will be described with reference to FIG. That is, in FIG. 6, L ₃ / L ₁ = tan θ _{1 where} L ₁ : light receiving direction of light receiving means L ₂ : light receiving direction of auxiliary light receiving means L ₃ : distance between light receiving means and auxiliary light receiving means (measured value is a constant ) L ₁ = L ₃ / tan θ _{1 where} θ ₁ is the angle between L ₁ and L ₂ and d ₂ / d ₁ = cos θ _{2 where} θ ₂ = cos ^-1 (d ₂ / d ₁ ) L ₁ = L ₃ / tan (cos ⁻¹ (d ₂ / d ₁ ) −θ / 2) d ₁ : Actual through-hole image d ₂ : Through-hole image received by auxiliary light receiving means θ ₂ : Through-hole image and real surface of auxiliary light receiving means Is the angle formed by
The relationship between the angles is therefore θ ₂ = θ ₁ + θ / 2, where L is the angle of view of the lens. Sand, 180 ° in FIG. 6 _{- (90 ° + θ 1)} = θ / 2 + θ 3 θ 3 = 180 ° - (90 ° + θ 1) -θ / 2 θ 2 = 180 ° - (90 ° + θ 3) θ ₂ = 180 ° − (90 ° + (180 ° − (90 ° + θ ₁ ) −θ /
2)) = 180 °-(90 ° + (90 ° -θ ₁ ) -θ / 2) = 180 °-(180 ° -θ ₁ -θ / 2) = θ ₁ + θ / 2 θ ₁ = 180 °- (90 ° + θ ₁ ) = θ / 2 + θ ₃ (θ: 300mm at right angle to the lens, 8 ° at telephoto, 25mm: 85
° 50mm: 47 °) L ₁ = L ₃ / tan (cos ^-1 (d ₂ / d ₁ ) −θ / 2) If the reference hole drilling surface has an inclination θ _F , θ ₂ = θ It becomes ₁ + θ / 2-θ _F.

The L ₁ sensed here is used as a surface position reference signal generating means (27).
Remember.

Reference example 1 25mm f1.8 wide-angle lens, 50mm f1.4 standard lens, 300mm f4
Each telephoto lens is fixed to the tip of the CCD camera, and the size (magnification), resolution (δ), and depth of field (D) on the monitor (display section) are fixed.
Were compared.

The magnification and resolution are obtained by the geometrical imaging size calculation method.

In Fig. 4, X: Actual dimension x: Imaging dimension sensed by CCD camera L: Subject distance F: Focal length At this time, the relation of x = FX / L is established.

The size (x ') of the object displayed on the monitor (display unit) after being corrected by the device and its magnification are obtained as follows.

x '= (imaging size: x) x (correction value) / (effective image size)
(Mm) Magnification = x ′ / X The resolution (δ) is calculated as follows.

δ = 1 / {(magnification) × (number of monitor pixels) / (monitor size)} (pixels / mm) Depth of field calculation In FIG. 5, d _{1 is the} rear depth of field d _{2 is the} front depth of field. Depth d ₃ : Depth of focus L: Object distance δ: Allowable circle of confusion.

F: focal length f: aperture value, D: depth of field is calculated by the following formula.

D = d ₁ −d ₂ = F ² L / {F ² − (L−F) δf} −F ² L / F ² + (L−
F) δf} (mm) Distance between objects L = 700mm If the actual size of the object is X = 6.5φ, then with a telephoto lens of 300mm f4 (δ = 0.03), the depth of field:
D is required for:

D = 300 ² × 700 / {300 ² − (700−300) × 0.03 × 4} −30
0 ² × 700 / {300 ² + (700−300) × 0.03 × 4} = 0.75 mm For wide-angle lenses and standard lenses, similar calculations are also shown below.

A 300mm f4 telephoto lens is desirable in terms of required accuracy and depth of field.

(G) Effect of the Invention Therefore, according to the present invention, it is possible to judge the three-dimensional suitability of the through hole formed in the measured object at a position distant from the measured object. Therefore, when the measured object moves on the line, it moves. It is possible to measure even if the time to stop is short.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of an embodiment of the present invention. FIG. 2, FIG. 3, FIG. 4, FIG. 5, and FIG. It is a block diagram of a prior art example. (11) …… DUT, (13) …… through hole, (17) …… background, (18) …… illuminating means, (19) …… light receiving means, (20)
...... Auxiliary light receiving means, (21) ...... Two-dimensional discriminating means, (25)
... Computing means, (26) One-dimensional discriminating means

Claims (1)

(57) [Claims] 1. An illumination means for projecting light onto a surface of an object to be measured and an object to be measured having a through hole formed therein are positioned on the opposite side of the object to be measured with respect to the illumination means when the object to be measured is placed. Depending on the background that is relatively dark compared to the reflected light that reflects the illumination from the illumination means on the surface of the object to be measured, and the light and darkness that senses and senses the reflected light that is installed toward the through-hole surface and reflected by the surface of the workpiece. A light receiving means for generating a signal, the light receiving means is installed at an angle to the through hole, and an auxiliary light receiving means for detecting the reflected light reflected on the surface of the workpiece and generating a signal according to the detected light and darkness, Two-dimensional discriminating means for comparing a desired reference through-hole image with the through-hole image sensed by the light receiving means as a dark part of the background passing through the through hole without generating reflected light, and the light receiving means and the auxiliary light receiving means sensing as a dark part Compare the through hole images By calculating the difference between both through-hole images calculated by the calculating means and the desired reference through-hole image by comparing the difference between the through-hole images obtained by both light receiving means, the desired reference A three-dimensional position measuring device for a through hole, comprising: a one-dimensional discriminating means for obtaining a difference between a distance between the through hole and the light receiving means and a distance between the through hole and the light receiving means.