TWI797039B - Measurement system - Google Patents

Abstract

A measurement system suitable for measuring the contour of an object. The measurement system includes multiple light sources, a calibration unit, a sensor, multiple alignment auxiliary units, and a calculation unit. The light sources are respectively used to project onto a part of the object, wherein there is an overlapping area when each of adjacent two of the light sources are projected onto the object. The calibration unit is set at the position corresponding to the object. The sensor is used to receive the contour information reflected when the light sources project onto the object. The alignment auxiliary units are respectively arranged at the position corresponding to the overlapping area in the calibration unit. The calculation unit is used to receive the contour information obtained by the sensor to calculate the contour of the object.

Description

measuring system

The present invention relates to a measuring system, and in particular to a measuring system for measuring the contour of an object.

The general non-contact profile measurement adopts the laser light source scanning method, by projecting the laser beam on the surface of the object to be measured to form a section line, and then the information of the section line is sensed by the optical sensor, and passed through Analyze to obtain the height information of the surface of the measured object, that is, the contour information. In order to be able to determine the size of the profile, a mapping is required from points in the plane of the optical sensor to points in the plane of light projected onto the measured object, so that the coordinates in the plane of the optical sensor can be transformed into real-world coordinates . The process of obtaining such a map is generally called calibration. Due to the unknown scale of the map, the unknown projection distortion of the light plane relative to the optical sensor and the unknown distortion of the optics, this calibration is generally determined by means of measurements of a reference object.

However, in the field requiring high-precision wide-field measurement, usually multiple sets of laser light sources and optical sensors are required to measure the measured object in segments at the same time, because the information received by the optical sensors is affected by different lasers. The influence of the hardware conditions and setting conditions of the light source makes the benchmarks different, resulting in the accuracy of each set of profile information obtained by the optical sensor is somewhat different, and cannot be directly used in parallel, resulting in the overall profile information of the measured object being unable to be measured. Learn exactly.

One aspect of the present invention is to provide a measurement system suitable for measuring the contour of an object. The measurement system includes multiple light sources, a calibration unit, a sensor, multiple alignment auxiliary units and a calculation unit. A plurality of light sources are respectively used to project to a part of the object, wherein every two adjacent light sources have an overlapping area when projected to the object. The calibration unit is set corresponding to the position of the object. The sensor is used for receiving the profile information reflected when the light sources are projected onto the object. A plurality of alignment assisting units are respectively arranged at positions corresponding to the overlapping areas in the calibration unit. The calculation unit is used for receiving the outline information obtained by the sensor to calculate the outline of the object.

In some embodiments, the calibration unit includes a plurality of serrations, wherein each serration has a tip and a valley is formed between two adjacent serrations.

In some embodiments, the alignment auxiliary unit includes two connected side parts and a pointed part disposed in the middle of the two side parts, wherein the side part can be placed on one side of the zigzag part of the alignment unit.

In some embodiments, the height of the tip is not equal to the height of the prong.

In some embodiments, the calculation unit calculates the correlation coefficient on the data of the two contour information in the overlapping area to obtain the merge position of the contour information obtained by the two light sources corresponding to the overlapping area.

…(1) 其中， X _i 為物體的輪廓資訊在X軸的位置， Z _i 為物體的輪廓資訊對應 X _i 位置的高度，

為 X ₁ 至 X _n 的平均數，

為 Z ₁ 至 Z _n 的平均數。 In some embodiments, the calculation unit calculates the correlation coefficient through formula (1);

...(1) Among them, X _i is the position of the object's contour information on the X axis, Z _i is the height of the object's contour information corresponding to the position of _Xi ,

is the average of _X1 to _Xn ,

is the average of Z ₁ to Z _n .

In some embodiments, the calculation unit sets the position of the data with the highest correlation coefficient among the data of the two contour information in the overlapping area as the merged position.

In some embodiments, the light sources are laser light.

To sum up, through the alignment auxiliary unit, it can be known that two adjacent light sources are projected to the overlapping area of the measurement object, and then by calculating the correlation coefficient of the contour information of the overlapping area, the obtained value obtained by the two adjacent light sources can be obtained. The merged position of the contour information of the measured object is then processed to obtain the overall contour information of the measured object.

In order to make the above and other objects, features, and advantages of the present invention more comprehensible, preferred embodiments of the present invention will be exemplified below in detail together with the attached drawings.

Please refer to FIG. 1 , which is a schematic diagram of a measuring system according to an embodiment of the present invention. Measurement system 10 includes a plurality of light sources 12 and sensors 14 . The light source 12 is suitable for illuminating the measurement object 16 with an incident light plane 18 , which can also be referred to as a sheet of light. The sensor 14 is adapted to detect light 20 reflected from the measurement object 16 and to generate an image from this reflected light 20 . In an embodiment, the measurement system 10 also includes a computing unit 24 suitable for storing and/or analyzing the images recorded by the sensor 14 .

In one embodiment, the light source 12 is laser light, so that the light plane 18 forms a laser plane.

Please also refer to Figure 2. FIG. 2 is a schematic diagram of a measurement system 10' with a calibration unit according to an embodiment of the present invention. As shown in FIG. 2 , a calibration unit 32 is also included in the measurement system 10 ′, which is brought into corresponding positions in the light plane 18 . In one embodiment, the calibration unit 32 includes a plurality of saw-toothed portions 34 , wherein each saw-toothed portion 34 has a tooth tip, and wherein tooth valleys are formed between two adjacent saw-toothed portions 34 . As such, the calibration unit 32 includes a plurality of points whose relative distances therebetween have been predetermined. Through the calibration unit 32 , the calculation unit 24 can accurately calculate the contour information of the measuring object through the reflected light information received by the sensor 14 .

As mentioned above, the plurality of light sources 12 of the measurement system 10 respectively project onto a part of the measurement object 16, and receive the reflected light through the sensor 14 to obtain the profile information of each part of the measurement object 16, and the information can be sent to the calculation unit 24 to analyze and generate corresponding contour images. However, due to the influence of hardware conditions and installation conditions of each light source 12 , there are differences in benchmarks, resulting in the accuracy of each set of profile information obtained by the optical sensor is somewhat different, and cannot be directly used in parallel.

Please refer to Figure 3 and Figure 4 together. FIG. 3 is a schematic diagram of an alignment auxiliary unit according to an embodiment of the present invention. FIG. 4 is a schematic diagram of a measuring system 10'' according to an embodiment of the present invention. As shown in FIG. 4 , the measurement system 10 ″ also includes a plurality of alignment auxiliary units 40 (only one is shown in the figure), and the alignment auxiliary units 40 are located at the overlapping area where adjacent light sources 12 project to the calibration unit 32 tooth valley. In one embodiment, as shown in FIG. 3A , the alignment auxiliary unit 40 has two connected side parts 41 and a pointed part 43 disposed in the middle of the two side parts. The side of the alignment auxiliary unit 40 can be completely conformed to one side of the saw-tooth portion 34 of the alignment unit 32 , so that the alignment auxiliary unit 40 can be completely and firmly disposed on the gear housing of the alignment unit 32 . In one embodiment, the height of the tip 43 is not equal to the height of the tooth tip of the sawtooth-shaped portion 34. Preferably, the height of the tip 43 is much smaller than the height of the tooth tip, as shown in FIG. 4, so that the calibration unit 32 An irregular shape is formed in the regularly arranged zigzag portion 34 , and the irregular shape is located in the overlapping area where two adjacent light sources 12 project to the calibration unit 32 . However, the present invention is not limited thereto, and the shape of the alignment auxiliary unit 40 can be designed correspondingly according to the shape of the calibration unit, as long as the originally regularly arranged calibration units can form an obviously irregular and easily identifiable shape in the overlapping area That's it. In this way, when the calculation unit 24 is analyzing the contour information, it can be known that the position corresponding to the alignment auxiliary unit 40 is the overlapping area projected by the two light sources 12 through the information given by the alignment auxiliary unit 40. This area It is the position where the outline information will be merged later.

…(1) 其中， X _i 為每一個數據在座標系統中的X軸座標（其代表被量測之物體的輪廓資訊在X軸的位置）， Z _i 為每一個數據在座標系統中的Z軸座標（其代表被量測之物體的輪廓資訊對應 X _i 位置的高度），

為 X ₁ 至 X _n 的平均數，

為 Z ₁ 至 Z _n 的平均數。 Please refer to FIG. 5A . FIG. 5A shows the contour information of the overlapping area obtained by the measuring system 10 ″ in FIG. 4 . Figure 5A (a) is the contour information of the overlapping area obtained by the light source 12 on the left side of the measurement system 10'', and Figure 5A (b) is the overlapping area obtained by the light source 12 on the right side of the measurement system 10'' profile information for . Since these two pieces of contour information are obtained through different light sources, the information standards of the two are not the same, and they must be calibrated before they can be merged. In one embodiment, the computing unit 24 records the contour information received by the sensor in an independent coordinate system, and then performs data normalization on the contour information to obtain the data in FIG. 5A . Next, the calculation unit 24 calculates the correlation coefficient of the data in the two graphs through the formula (1).

...(1) Among them, X _i is the X-axis coordinate of each data in the coordinate system (it represents the position of the profile information of the object to be measured on the X-axis), Z _i is the Z of each data in the coordinate system Axis coordinates (which represent the height of the contour information of the measured object corresponding to the _Xi position),

is the average of _X1 to _Xn ,

is the average of Z ₁ to Z _n .

…(2)

…(3)

…(4) The correlation coefficient r is the covariance of X and Z divided by the product of the standard deviation of X and the standard deviation of Z. The common variable of X and Z can be expressed by formula (2), the standard deviation of X can be expressed by formula (3), and the standard deviation of Z can be expressed by formula (4). Therefore, formula (1) can be obtained by dividing formula (2) by the product of formula (3) and formula (4).

…(2)

...(3)

…(4)

Specifically, the calculation unit 24 can combine the data of each position in Figure 5A (a) with each of the data corresponding to the same position (that is, on the same X coordinate) in Figure 5A (b) in Figure 5A (a). The correlation coefficient of the two is calculated from the data, wherein each data represents the height of one position of the measured object's outline. Next, the calculation unit 24 shifts all the data in Figure 5A (a) by one unit (for example, shifts one X coordinate unit to the right), and then compares each data in Figure 5A (a) with Figure 5A (b) Corresponding to each data at the same position after displacement in Figure 5A (a) and calculating the correlation coefficient of the two, and so on until all possible correlation coefficients are completed. Among all the calculated correlation coefficients, the higher the correlation coefficient is, the closer the data of the two charts are to the concatenated position. Therefore, after the calculation of the correlation coefficients of all the data is completed, the data with the largest correlation coefficient is the position where parallel connection can be performed (that is, the same position in Fig. 5A (a) and Fig. 5A (b)). As shown in Fig. 5B, Fig. 5B shows the complete contour information obtained after merging the contour information in Fig. 4A, wherein the left half corresponds to the contour information obtained by projecting the left light source 12, and the right half Corresponding to the contour information obtained by projecting through the right light source 12 .

It can be seen from the above-mentioned embodiments that through the alignment auxiliary unit provided by the present invention, it is possible to know the overlapping area where two adjacent light sources are projected onto the measurement object, and then calculate the correlation coefficient by calculating the contour information of the overlapping area, and obtain The merged position of the contour information obtained by two adjacent light sources is then merged to obtain the overall contour information of the measured object.

Although the present invention has been disclosed with preferred embodiments, it is not intended to limit the present invention. Anyone skilled in this art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the present invention The scope of protection shall be determined by the scope of the attached patent application.

10, 10’, 10’’: measuring system 12: Light source 14: Sensor 16: Measuring Objects 18: Incident light plane 20: reflected light 24: Calculation unit 32: Calibration unit 34: zigzag part 40: Alignment auxiliary unit 41: Edge 43: tip

FIG. 1 is a schematic diagram illustrating a measurement system according to an embodiment of the present invention;

FIG. 2 is a schematic diagram illustrating a measurement system with a calibration unit according to an embodiment of the present invention;

FIG. 3 is a schematic diagram illustrating an alignment auxiliary unit according to an embodiment of the present invention;

FIG. 4 is a schematic diagram illustrating a measurement system according to an embodiment of the present invention;

Figure 5A shows the contour information of the overlapping area obtained by the measurement system in Figure 4; and

FIG. 5B shows the complete contour information obtained after the contour information in FIG. 5A is merged.

10": measuring system

12: Light source

14: Sensor

20: reflected light

24: Calculation unit

34: zigzag part

41: Edge

43: tip

Claims (8)

A measuring system, adapted for measuring the contour of an object, comprising: A plurality of light sources are respectively used to project to a part of the object, wherein every two adjacent light sources have an overlapping area when projected to the object; A calibration unit, set at the position corresponding to the object; a sensor for receiving contour information reflected when the light sources are projected onto the object; A plurality of alignment auxiliary units are respectively arranged at positions corresponding to the overlapping areas in the calibration unit; and A calculation unit is used for receiving the outline information obtained by the sensor to calculate the outline of the object. The measurement system according to claim 1, wherein the calibration unit includes a plurality of sawtooth-shaped parts, wherein each sawtooth-shaped part has a tooth tip, and a tooth valley is formed between two adjacent saw-tooth-shaped parts. The measurement system as described in claim 2, wherein the alignment auxiliary unit includes two connected side parts and a pointed part arranged in the middle of the two side parts, wherein the side part can be placed on the zigzag part of the calibration unit on one side. The measurement system as claimed in claim 3, wherein the height of the tip is not equal to the height of the tooth tip. The measurement system according to claim 1, wherein the calculation unit calculates the correlation coefficient of the data of the two contour information in the overlapping area to obtain the merge position of the contour information obtained by the two light sources corresponding to the overlapping area. The measurement system as described in claim 5, wherein the calculation unit calculates the correlation coefficient through formula (1);

...(1) Among them, X _i is the position of the object's contour information on the X axis, Z _i is the height of the object's contour information corresponding to the position of _Xi ,

is the average of _X1 to _Xn ,

is the average of Z ₁ to Z _n . The measurement system according to claim 6, wherein the calculation unit sets the position of the data with the highest correlation coefficient among the data of the two contour information in the overlapping area as the concatenated position. The measuring system as described in claim 1, wherein the light sources are laser light.

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