JPH076774B2 - Three-dimensional shape measuring device by optical cutting method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to an improvement of a three-dimensional shape measuring apparatus by a light section method.

<Prior Art> FIG. 5 shows an outline of a three-dimensional shape measuring apparatus by a light section method. When the slit light 12 is emitted from the light source 11, a light cutting line 14 is obtained on the surface of the DUT 13, and this is cut by the CCD.
The image is taken by the imaging device 15 such as a camera. Then, by processing the data of the light section image obtained by the image pickup device 15 using the triangulation method, the position of each point on the surface of the object to be measured 13 on three-dimensional coordinates is obtained to obtain three-dimensional shape data. Of.

<Problems to be Solved by the Invention> In such measurement by the light section method, the light source 11 and the imaging device are used.
The closer the angle θ with 15 is to 90 °, the easier the irregularities on the surface of the object to be measured 13 are detected, and therefore the measurement accuracy is improved. However, when the object to be measured 13 has a large unevenness, when the angle θ becomes large, a blind spot occurs and there are many missing portions where data cannot be obtained. There was a certain limit to the improvement.

In addition, in the conventional measuring device, measures such as measurement by putting the entire device and the DUT in a dark room to prevent noise such as disturbance due to light rays other than the slit light are taken, and the device is upsized. It was one of the causes of the high price.

The present invention has been made in view of these problems, and has been made for the purpose of improving the measurement accuracy by the optical cutting method with a relatively simple structure.

<Means for Solving the Problems> In order to achieve the above-mentioned object, the three-dimensional shape measuring apparatus according to the light cutting method of the present invention includes a slit light irradiating means for obtaining a light cutting line of an object to be measured, and Placed at a distance from
Further, two light cutting line imaging means that circulate around the object to be measured together with the slit light irradiating means while maintaining a constant positional relationship with the slit light irradiating means, and two light cutting lines obtained by each imaging means. Processing means for recognizing the three-dimensional shape of the object to be measured from the image. When the difference between the recognition results of the two light section images is within a predetermined reference value, this processing means takes the average value of the two as the processing result, and when the difference between the recognition results exceeds the reference value, the respective processing results are calculated. The continuity of the recognition result is determined, and the recognition result having the continuity is adopted as the processing result.

In the above, the case where the difference in the recognition result exceeds the reference value includes the case where the difference between the obtained data is large and the case where one of the data is missing.
This corresponds to the case where noise due to disturbance is superimposed on the output of one of the image pickup means, or a case where a blind spot occurs in one of the image pickup means and a part of the light section image is missing.

FIG. 1 is a diagram showing a configuration of the present invention, in which A is a slit light irradiating means, B ₁ and B ₂ are optical cutting line imaging means, C is a processing means, D is an object to be measured, and E is a rotating device. . The orbit of the slit light irradiating means A and the light section line imaging means B ₁ and B ₂ is
The light irradiating means A and the imaging means B ₁ and B ₂ may be revolved around the fixed object to be measured D, which is relative to the object to be measured D. The image pickup means B ₁ and B ₂ may be fixed and the DUT may be rotated at that position. F is an external synchronizer for synchronizing the operations of the above-mentioned means, G
Is a storage device for storing the output of the processing means C, and H is an output device for outputting the data stored in the storage device G as required.

<Operation> Since each image pickup means images the optical cutting line from different directions, the probability that a blind spot occurs at the same time in both image pickup means is much smaller than in the case where there is one image pickup means. It is possible to increase the angle θ of the to some extent, and it is easy to improve the measurement accuracy. Also, the three-dimensional shape is recognized by the average value of the light section images obtained by each image pickup means,
If the difference between the recognition results is large, the recognition result having the continuity is adopted, so that even if the data of one of the image pickup means is abnormal, the data of the other image pickup means is automatically complemented.

Therefore, the probability of being affected by noise is low, and there is no missing part or data with few missing parts is obtained.
The measurement can be performed without providing a special dark room and the measurement accuracy is improved.

<Example> Next, one example shown in the figure will be described. FIG. 2 is a plan view showing the outline of the apparatus, FIG. 3 is a block diagram, and FIG. 4 is a flow chart of the control means.

In FIG. 2, 1 is a light source which is a slit light irradiating means,
Reference numerals 2a and 2b are image pickup cameras which are light section line image pickup means, and 3 is an object to be measured.

The light source 1 is arranged on a circumference 1'having a radius r centered on the origin O so as to irradiate the slit light 4 which spreads in a direction perpendicular to the plane of the drawing including the origin O, and is always oriented to the origin O. Is provided so as to rotate on the circumference 1'at a predetermined speed. Further, the image pickup cameras 2a and 2b are arranged at a position equidistant from the light source 1 on a tangent line of the circumference 1'passing through the light source 1 and at an angle θ with respect to the light source 1, and always facing the origin O. It is provided so as to rotate together with 1. Θ above
Is selected at 45 °, for example. Further, the DUT 3 has an origin O
The imaging cameras 2a and 2b are configured so that the light cutting line 5 generated on the DUT 3 by the slit light 4 enters the field of view thereof.

The light source 1 may be a light source of the same type as that used in the conventional three-dimensional shape measuring device according to the conventional light-cutting information, and the imaging cameras 2a and 2b may be a third-order light source according to the conventional light-cutting method. What is used in the original shape measuring apparatus, for example, a CCD camera or the like can be appropriately used.

In the block diagram of FIG. 3, 6 is an image processing device, 7 is a rotation driving unit, and 8 is an output device. The main part of the image processing device 6 is composed of a computer, and a CPU 61 which is the center of calculation and various controls, a ROM 62 which stores control programs and the like, a RAM 63 which stores various obtained data, and a synchronizing signal are generated. In addition to the clock circuit 64, an appropriate input / output circuit (not shown) and the like are provided. Further, the rotation drive unit 7 is appropriately configured to drive the image pickup cameras 2a and 2b of the light source 1 by a control signal from the image processing device 6. Further, the output device 8 outputs the data of the recognition result of the three-dimensional shape obtained by the image processing device 6, and is composed of, for example, a CRT display or a printer.

The measuring device of this example is configured as described above,
First, the operation of the first invention will be described with reference to the flowchart of FIG.

Each imaging camera 2a, 2b is controlled by a synchronization signal,
First, in step S1, the respective image signals, that is, the light section images 5a and 5b are alternately input. This input switching is performed, for example, every 1/30 seconds. In step S2, the light-section images 5a and 5b are binarized by a comparator to enable high-speed signal processing, and each data binarized in step S3
By processing 51a, 51b, the position of the surface of the DUT 3 on the three-dimensional coordinates is calculated, and the recognition results 52a, 52b of the three-dimensional coordinates are obtained.
Since the width of the light cutting line 5 varies depending on the distance between the light source 1 and the DUT 3, the inclination of the surface, and the like, the calculation is performed so as to detect the coordinates of the pixel forming the center of the line. Since the radius r centering on the origin O and the angle θ of the imaging cameras 2a and 2b with respect to the slit light 4 are known, the process of step S3 is appropriately performed by a known procedure generally performed by the conventional light cutting method. It can be carried out.

In step S4, the coordinate data of each point obtained as the above recognition results 52a, 52b is compared with the coordinate data of the other camera immediately before that, and if the difference between the two is within a preset reference value, The average value of both is calculated in S5, and this is output as the processing result 53. If the difference exceeds the reference value, the process proceeds to step S6, where each recognition result 52a,
The continuity of 52b is determined, the recognition result having the continuity is adopted, and this is output as the processing result 53 '.
The above processing is sequentially performed for each point on the surface of the DUT 3. These output data are stored in the RAM 63 in step S7 and are ready for future use. This continuity is determined, for example, by sequentially comparing the data before and after the corresponding portion for a certain period of time and determining whether the variation of the data is within a certain reference value. By properly selecting according to the shape of 3 and the like, it is possible to obtain a measurement result without noise or omission.

As shown by the broken line, in the embodiment, when the difference between the recognition results 52a and 52b exceeds the reference value in step S4, the respective recognition results are processed as they are separately from the above processing result 53 ′.
It is stored as 53a and 53b (step S
8). Further, although the imaging cameras 2a and 2b are arranged symmetrically on both sides of the light source 1, the present invention can also be applied to the case where the cameras are arranged asymmetrically with respect to the light source or arranged on the same side with respect to the light source. it can.

<Effects of the Invention> As is apparent from the above-described embodiments, the three-dimensional shape measuring apparatus of the present invention images the optical cutting lines from different directions by the two optical cutting line imaging means, and obtains them by each imaging means. When the difference between the light-section images is small, the three-dimensional shape of the measured object is recognized based on the average value.

Further, when the difference between the light-section images obtained by the respective image pickup means is large, the three-dimensional shape of the object to be measured is recognized in consideration of continuity.

Therefore, since the average value of the two light section images is used, it is unlikely to be affected by noise, and high-precision measurement is possible without providing a special dark room. At the same time, the probability of blind spots occurring in both image capturing means is small, and even if a blind spot occurs in one of the image capturing means, the data can be complemented by the other image capturing means, so measurement by increasing the angle with the slit light source. The accuracy can be improved, and it becomes easy to obtain the measurement result without the influence of noise or lack.

The present invention has the advantages described above, and a highly accurate three-dimensional shape measuring device by the optical cutting method can be realized at a low cost with a relatively simple structure.

[Brief description of drawings]

FIG. 1 is a diagram showing the structure of the present invention, FIG. 2 is a schematic plan view of an embodiment, FIG. 3 is a block diagram, FIG. 4 is a flow chart of a control procedure, and FIG. 5 is a general optical cutting method. It is an explanatory view of a different three-dimensional shape measuring apparatus. 1 ... Light source (slit light irradiation means), 2a, 2b ... Imaging camera (light cutting line imaging means), 3 ... Object to be measured, 4 ... Slit light, 5 ... Light cutting line, 6 ... Image Processing device (processing means), 7 ... Rotation drive unit, 8 ... Output device, 61 ... CP
U.

Claims (1)

[Claims] 1. A slit light irradiating means for obtaining a light cutting line of an object to be measured and a slit light irradiating means which are arranged apart from each other and maintain a constant positional relationship with respect to the slit light irradiating means. At the same time, two light cutting line imaging means that circulate around the object to be measured, and recognition processing of the three-dimensional shape of the object to be measured are respectively performed from the two light cutting images obtained by each of the imaging means. If the difference is within a predetermined reference value, the average value of both is used as the processing result, and if the difference in recognition result exceeds the reference value, the continuity of each is judged and the recognition result with continuity is used as the processing result. A three-dimensional shape measuring apparatus by a light-section method, which comprises: a processing unit to be used.