JPH03186705A - Three-dimensional shape dimension measuring instrument - Google Patents

Abstract

PURPOSE:To execute the measurement at high speed and with high reliability by extracting an end point by comparing a difference value and a threshold in each position of height information of an object, based on three-dimensional coordinates of the object, and obtaining exactly a step difference and the dimension of a clearance which the object has by a small operation quantity. CONSTITUTION:From a slit light source 1, a slit light L is projected to an object. Subsequently, from a coordinate arithmetic part 4 in a position in which the slit light L is projected, three-dimensional coordinates (Y, Z) of a bumper being an object to be measured and a reference block are obtained. Also, in the arithmetic part 4 the center position of the slit light is detected with high accuracy by deriving the centroid of its reflecting signal intensity at every scanning line, in an optical cut image projected to the object and obtained by executing an image pickup by a television camera 2. In such a way, from the center position of the obtained slit light and the positions of the camera 2 and the light source 1, three-dimensional coordinates (Y, Z) are detected by the principle of a trigonometrical survey.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention measures the three-dimensional shape and dimensions of a specific region of an object. The present invention relates to a three-dimensional shape and dimension measuring device for measuring.

[Prior art]

Conventionally, methods for detecting steps in an object include a laser slit light irradiation means that irradiates a slit light emitted from an infrared laser across the roof part and the sliding roof part of a car body, and a visual system that images the irradiated part of the laser slit light. A sensor captures an image of the area irradiated with the laser slit light from this visual sensor and converts it into a binary image. Based on the detection of the amount of deviation of the line corresponding to the laser slit light in the binarized image, the roof part and the sliding wheel are detected. - There is a sliding roof level difference detection device for an automobile comprising an image processing means for detecting a level difference between the roof part and the roof part.
-61107).

However, since the conventional apparatus measures the level difference by detecting the amount of deviation of the line corresponding to the laser slit light in the binarized image, the detection accuracy is insufficient, which is a problem that must be solved in practice.

Furthermore, conventionally, in the production process, dimensions such as steps and gaps in an automobile body have been measured manually using calipers or a gap gauge.

However, the former method has variations depending on the operator and even the same worker depending on the conditions, lacks measurement reliability, and has problems that need to be solved in practice. In order to measure gaps and steps in a specific area of the object, three-dimensional coordinate values of the surface of the object are required. Conventional contact-type and spot-light type three-dimensional coordinate measurement has the disadvantage that it takes time to measure many points in order to accurately measure gaps and steps on the surface of an object. there were. Also, in a method using planar image processing using slit light, the position (i, j) of the slit light on the screen
If only the three-dimensional coordinates of the object are obtained, it is not possible to measure gaps and steps on the surface of the object.

[Purpose of the invention]

Therefore, in the present invention, the three-dimensional coordinates of the object surface can be detected at high speed and with high precision using a three-dimensional visual sensor as a coordinate calculation unit that can detect the three-dimensional coordinates of the object surface at high speed and with high precision using slit light. and measure multiple points at once, Part 3
Using dimensional coordinates, we have made it possible to measure gaps and steps in the shape of objects at high speed and with high precision.

It is an object of the present invention to solve the above-mentioned conventional problems and to reduce gaps and steps (or height and width) of objects (or both).
Simple, high-speed, and highly reliable measurement (simultaneously), for example, 3D shape and dimension measurement that can measure dimensions for car body construction, gaps and steps between car parts and reference blocks (which give reference coordinates) The goal is to provide equipment.

[Structure of the invention]

The three-dimensional shape measuring device of the present invention faces an object having at least two ends forming at least one of a gap and a step, and emits slit light from a slit light source at a constant angle toward the surface of the object. an imaging unit that images a light section line generated by the slit light projected by a TV camera; a feature point detection unit that extracts two feature points from the relationship between the difference in three-dimensional coordinate values obtained for each scanning line of the object surface and a reference value and detects the three-dimensional coordinate values; and a dimension calculation section that calculates the relative positional relationship between the two feature points based on the difference between the respective three-dimensional coordinate values of the two feature points detected by the section.

[Function and effect of the invention]

The three-dimensional shape and dimension measuring device of the present invention having the above configuration includes:
The imaging unit uses a television camera to image a light cutting line generated by slit light from a slit light source that reflects at least one of a step and a gap in a specific area of the object. Then, based on triangulation from the center of gravity of the intensity distribution for each scanning line of the light section line image obtained by the feature point detection unit,
From the detected three-dimensional coordinates of the surface of the object, three-dimensional coordinates of feature points that define relative dimensions regarding gaps and steps in a specific area are detected. Next, the dimension calculation section calculates the relative positional relationship between the two feature points based on the difference in the three-dimensional coordinate values of the feature points detected by the feature point detection section. That is,
The dimensions measured by the device of the present invention are, for example, the relative distance between a door and a fender of an automobile body, such as a step or a gap. Here, the step or gap is calculated from the difference or distance between the three-dimensional coordinates of the end points of the obtained slit light image by projecting slit light from a slit light source as a three-dimensional visual sensor onto the object.

In addition to the above, in the present invention, when the object has a rounded end, the feature point detection section adds a pre-prepared correction value to the end point of the slit light image. It is possible to detect feature points that closely match the actual edges of the
As a result, compared to the case where no correction value is used, there is an advantage that the gap size can be measured accurately.

Furthermore, in the present invention, three parts of the object surface along the optical cutting line are
Dimensional coordinates can measure multiple points at once with high speed and precision 3
Because it uses a dimensional vision sensor, it can measure the dimensions of steps and gaps in objects at high speed and with high precision. In other words, in conventional contact type or spot light type three-dimensional coordinate measuring machines,
The three-dimensional coordinates of the end points that define the dimensions of the object cannot be determined without moving the sensor or the object multiple times and taking detailed measurements, which takes a lot of time. but,
In dimension measurement using this 3D vision sensor, the 3D coordinates of the edge can be obtained simply by positioning the object within the measurement range of this 3D vision sensor, allowing for high-speed, high-precision shape and dimension measurement. I can do it.

As described above, the three-dimensional shape and dimension measuring device of the present invention can measure steps and gaps in an object non-contact, at high speed, and with high accuracy, and has a great practical effect.

[Other compositions of the invention]

Other inventions include, in addition to the above-described configuration, a determining section that determines the acceptability of the dimension values calculated by the dimension calculation section.

[Other effects of the invention]

The determination unit compares the measured dimensions with a pre-given quality standard, determines the quality based on whether the dimensions are within the standard, and outputs the results. Based on the pass/fail results output from the determining section, it can be easily determined whether the steps and gaps in the car body are within the specifications.

EMBODIMENT OF THE INVENTION Hereinafter, the three-dimensional shape and dimension measuring device of this invention is demonstrated based on an Example.

[First Embodiment] The three-dimensional shape and dimension measuring device of the first embodiment is an example of a dimension measuring system for automobile bumper assembly.As shown in FIGS. 1 to 6, the three-dimensional visual sensor is a slit light source 1. The imaging unit 3 consisting of the television camera 2 and the coordinate calculation unit 4 are instructed to do so. The coordinate calculation unit 4 includes a slit light center detection circuit 5 for calculating the center of gravity to obtain highly accurate three-dimensional coordinates, a slit light reflection intensity detection circuit 7 for reducing the influence of the surface texture of the object 6, It is composed of a slit light projection intensity setting circuit 8 and a coordinate lookup table 9.

An automotive bumper assembly dimension measurement system using a three-dimensional visual sensor and a dimension measurement algorithm is obtained from a three-dimensional visual sensor, a robot for positioning the three-dimensional visual sensor, a robot controller, and a three-dimensional visual sensor. It has a feature point detection unit 1O and a dimension calculation unit 11 that perform dimension processing on three-dimensional coordinates. That is, the feature point detection section 10 is composed of an end point detection circuit 12 that detects the end point of the light section line from the three-dimensional coordinates calculated by the coordinate calculation circuit 4' for each point on the light section line image.

Further, the dimension calculation unit (1) includes a subtraction circuit 13 that calculates the difference in three-dimensional coordinates of the detected end points.

The three-dimensional shape and dimension measuring device of the first embodiment having the above-mentioned configuration positions a three-dimensional visual sensor at a measurement position by a robot, and directs slit light from a slit light source 1 to an object 6.
project towards. Then, the three-dimensional coordinates (Y, Z) of the bumper, which is the object to be measured, and the reference block are obtained from the coordinate calculation unit 4 at the position where this slit light is projected.

The coordinate calculation unit 4 calculates the center position of the slit light for each scanning line in the light cutting line image projected onto the object and captured by the television camera by determining the center of gravity of the reflected signal intensity. Three-dimensional coordinates (Y, Z) are detected by the principle of triangulation from the center position of the slit light obtained by accurate detection and the positions of the television camera 2 and the slit light source l.

In the first embodiment, the slit direction of the projected pick-pocket light and the scanning direction of the TV camera are set to be spatially perpendicular.

Here, for example, when an area of 30 mm in the Y direction is imaged by the television camera 2 with 500 scanning lines, the pitch of data in the Y direction is approximately 0.06 mm, and the pitch of the data in the Y and Z directions is approximately 0.06 mm.
For dimensional coordinates, 500 points can be obtained at the same time with one light cutting line.

Next, the feature point detection unit 10 detects feature points that define dimensions from the three-dimensional coordinates obtained by the coordinate calculation unit 4. That is, in the case of the first embodiment, the physical edge forming the gap or step between the reference block and the automobile bumper where the object 6 faces is defined as a point (end point) where the coordinate value in the Z direction suddenly changes. Detect by asking. Specifically 3
The dimensional coordinates (Y, Z) are obtained from the coordinate calculation unit 4 as discrete values for each scanning line of the television camera 2, but are three-dimensional coordinates corresponding to the scanning line of the part where the reflected signal of the slit light is not obtained. Since this cannot be detected, a special value is set for the Z coordinate of this part to indicate that it is outside the range that can be obtained as a measured value. This is a value used as a flag to indicate that there is no reflected signal. For example, if the measured value of the Z coordinate is between -10 mm and +
If it can be obtained as a value of 10 mm, the value of this flag is set to a value that is significantly different from the measured value of 1000, for example. Next, at this Z coordinate, a difference between corresponding Z coordinates of adjacent scanning lines is calculated, and a point where the difference exceeds a threshold value can be detected as an end point.

The threshold value is determined according to the shape of the object in order to remove noise components. For example, when there is no reflected light signal in the gap as in the first embodiment, the corresponding Z coordinate is As mentioned above, since it is a flag value, the difference value at the end of the gap is essentially very large.
It can be set relatively large.

Furthermore, in the case where the object has a concave shape with a bottom, if there is a reflected signal from the bottom corresponding to the gap, the difference value of each Z coordinate will fall within the range of the measured values described above. By setting a small threshold, endpoints can be detected in the same way. Next, the dimension calculation unit 11 calculates the gap by subtracting the three-dimensional coordinates of the end point corresponding to the detected physical end in the Y direction as shown in FIG. The level difference is calculated by subtracting the coordinate values (Zja - Zjb). Then, the determination unit 14 compares the obtained dimensions with preset determination criteria,
When assembling, judge the quality of the dimensions, that is, the gap and step dimensions.

The first embodiment is based on the three-dimensional coordinates of the object obtained from the reflected slit light from the object imaged by a television camera, and the difference value and threshold value at each position of the height information (two coordinates) of the object. Since the endpoints are extracted by comparison with , accurate dimensions of steps and gaps in the object can be obtained with a small amount of calculations, and this has the advantage of enabling simple, high-speed, and highly reliable measurement.

In addition to the first embodiment described above, the feature point detection unit 10 may use a method of using coordinate values smoothed by a moving average or the like in at least one of the Z direction and the Y direction, or a method of using coordinate values smoothed by a moving average, etc. The center of gravity position can be determined by using the point where the curvature or curvature change is more than the threshold as the end point, or by using the difference in the Z direction or the difference in the difference in the Z direction. , there is a method of using this as an end point. The dimension calculation unit 11 calculates not only the difference between feature points but also the three-dimensional distance between two points, and uses this as the gap dimension. In the three-dimensional shape and dimension measuring device of the first embodiment, the same effects as described above can be achieved even with these combinations.

[Second Embodiment] The three-dimensional shape and dimension measuring device of the second embodiment is an example of a dimension measuring system for body installation, and as shown in FIGS. 7 and 8, a three-dimensional visual sensor is used as in the first embodiment. , a feature point detection unit 10 that performs dimension processing on the three-dimensional coordinates obtained from the three-dimensional visual sensor, and a dimension calculation unit 11. That is, the feature point detection unit 10 calculates the 3
End point detection circuit 1 that detects end points of optical cutting lines from dimensional coordinates
2, a correction value table 15, and a rounded portion detection circuit 16, and the dimension calculation section 11 is composed of a step dimension calculation circuit 11a and a gap dimension calculation circuit 11b.

The correction value table 15 calculates the coordinate values of the end points of the light cutting line by changing conditions such as the shape of a corner of the object to be measured, the slit light reflection intensity, the position and posture of the imaging section 3 with respect to the object, etc. , the difference between the apex of a part of the corner, that is, the coordinate value corresponding to the open tip of the object that defines the gap, is measured, and the difference value is stored as a correction value using each condition as a parameter. be. This is because if the end of the object has a curved shape, it becomes difficult to obtain a reflected signal of the projected slit light with a television camera, and it may become impossible to obtain three-dimensional coordinate values up to the end.

This is to ensure that the gap is properly obtained even in such a case.

The three-dimensional shape and dimension measuring device of the second embodiment having the above configuration positions the three-dimensional visual sensor at the measurement position and projects slit light from the slit light source l toward the object 6. The coordinate calculation unit 4 performs high-speed and high-precision coordinate calculation as described in the first embodiment. Next, first, feature points corresponding to the gaps are detected by the method described below. That is, in the end point detection circuit 12, the 3
An end point is detected from the dimensional coordinates in the same manner as in the first embodiment, and a pre-prepared correction value is added to the three-dimensional coordinates of the point, thereby detecting a point that coincides with a physical end.

In other words, the point where ΔZ exceeds the threshold THs in FIG.
) The three-dimensional coordinates of the end point on the fender side (Y J bs , Z J bs ) are obtained, and by adding a correction value to each of these Y coordinates, the Y coordinate of the opposing door and the tip of the fender can be removed. It can be inserted.

Next, the gap size calculation circuit 11b can obtain the gap size by subtracting the obtained Y coordinates of the tips of the door and the fender (lYjaS+y correction value al 1Yjbs+Y correction value bl). Further, the feature points corresponding to the step are detected by the method described below. That is,
The rounded portion starting point detection circuit 16 calculates the difference between the Z coordinates of each adjacent scanning line from the three-dimensional coordinates obtained by the coordinate calculation unit 4, in the same way as in the gap size measurement described above, and the difference exceeds the threshold value THd. The point beyond the point is detected as the starting point of the rounded part. Here, the threshold value THd is the threshold value T at the gap size.
Unlike Hs, it is set to a value that is larger than the noise of the difference, but small enough to extract the rounded part. Next, the step size calculation circuit 11a calculates the step by subtracting the Z coordinate of the detected rounded portion starting point (IZjad-Zjbdl).

As described above, in the second embodiment, even if the reflected signal cannot be obtained all the way to the edge of the object because the edge of the object has a curved shape, it is possible to accurately measure gaps and steps. It has many practical effects.

[Brief explanation of drawings]

1 to 6 respectively show a three-dimensional shape and dimension measuring device according to a first embodiment of the present invention. FIG. 1 is a block diagram of the device of the first embodiment, and FIG. FIG. 3 is a block diagram showing the specific contents of the device of the first embodiment, FIG. 4 is a diagram of the light section line image of the device of the first embodiment, and FIG. 5 is a diagram showing the details from the TV camera. An explanatory diagram of the output video signal, FIG. 6 is a flowchart diagram showing the measurement procedure in the first embodiment device, and FIGS. 7 and 8 are the second embodiment diagram.
FIG. 1 is a block diagram and a flowchart diagram of an example device. In the figure ■ ・ 2 ・ 3 ・ 4 ・ 5 ・ 6 ・ 7 ・ 8 ・ 9 ・ 10 ・ 1 l ・ 12 ・ 13 ・ l 4 ・ ・Slit light source, TV camera, imaging unit, coordinate calculation unit, detection circuit, object Object/Slit light reflection intensity detection circuit/Slit light projection intensity setting circuit/Coordinate lookup table/Feature point detection unit/Dimension calculation unit/End point detection circuit/Subtraction circuit/Judgment unit

Claims (1)

[Scope of Claims] Opposing an object having at least two ends forming at least one of a gap and a step, projecting slit light from a slit light source at a constant angle toward the surface of the object,
an imaging unit that images a light section line generated by the slit light with a TV camera; and an object detected by triangulation based on the position of the center of gravity of the intensity distribution for each scanning line in the light section line image from the TV camera. a feature point detection unit that extracts two feature points from the relationship between the difference in three-dimensional coordinate values obtained for each scanning line of the surface and a reference value and detects the three-dimensional coordinate values; a dimension calculation unit that calculates the relative positional relationship between the two feature points based on the difference in the respective three-dimensional coordinate values of the two feature points, and a dimension calculation unit that calculates the relative positional relationship between the two feature points based on the difference in the three-dimensional coordinate values of the two feature points, and a dimension calculation unit that calculates the relative positional relationship between the two feature points. and a three-dimensional shape and dimension measuring device that measures at least one of steps.