JP2006038590A - Three-dimensional shape measuring method and its device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a three-dimensional shape measuring method capable of optically performing three-dimensional measurement with sufficient precision, without accumulation of errors even if an object to be measured is large. <P>SOLUTION: An image of the object to be measured 1 is photographed with a camera 4, and the three-dimensional shape of the object 1 inside an imaging region S of the camera 4 is measured. In that case, long reference bars 14, 16 arranged along the object 1 and provided with a plurality of marks M, and a moving mechanism 18 which supports the camera 4 movably are provided. The three-dimensional shape of the object 1 is measured by converting respective measured values in imaging regions S images of the object 1 in which each comprising at least two marks M are photographed at different spots by moving the camera 4 supported by the moving mechanism 18, into the same coordinate system on the basis of the marks M. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a three-dimensional shape measuring method and apparatus for optically measuring the outer shape of an object to be measured in three dimensions.

Conventionally, using stripes such as moiré topography, projecting a striped pattern on the object to be measured, superimposing the stripe pattern deformed according to the shape of the object to be measured and the reference stripe pattern, and the difference frequency As an apparatus for measuring a three-dimensional shape of an object to be measured by analyzing moire fringes indicating contour lines generated as described above, for example, apparatuses as disclosed in Patent Document 1 and Patent Document 2 are known. In such an apparatus, a striped pattern formed on an object to be measured is imaged by a CCD camera and analyzed.
JP-A-53-68267 JP 61-260107 A

  However, with such conventional devices, when the object to be measured is small, sufficient measurement accuracy can be obtained even if the entire object to be measured is captured and analyzed with a CCD camera. If the whole object to be measured is imaged, sufficient resolution may not be obtained.

  In such a case, image a part of the object to be measured to measure the three-dimensional shape, and then change the location and image another part of the object to be measured to measure the three-dimensional shape. This is repeated to measure the entire three-dimensional shape. However, if the measured values divided and combined into the measured values of one reference coordinate system, an error will occur each time, and if many patches are combined, the error will occur. There is a problem that a large error occurs due to accumulation.

  An object of the present invention is to provide a three-dimensional shape measuring method and apparatus capable of optically measuring three-dimensionally accurately without accumulating errors even for a large object to be measured.

In order to achieve this problem, the present invention has taken the following measures in order to solve the problem. That is,
In a three-dimensional shape measurement method for imaging a measurement object with a camera and measuring a three-dimensional shape of the measurement object in an imaging region of the camera,
A long reference bar provided with a plurality of marks with known intervals is arranged along the object to be measured, and the object to be measured is picked up in an imaging region including at least two of the marks on the reference bar by the camera. Further, the camera is moved, the camera is moved, the object to be measured is imaged in an imaging area including at least two marks at different locations, and the measured values of the imaging area in which the object to be measured is imaged are marked. The three-dimensional shape measuring method is characterized in that the three-dimensional shape of the object to be measured is measured by converting to the same coordinate system based on the above.

  The reference bar is provided with a plurality of marks having the same shape at equal intervals, and detects the movement amount of the camera, and includes at least two marks at different locations based on the movement amount. 3D of the object to be measured is identified by identifying the mark included in the imaging area where the object is imaged, and converting each measurement value of the imaging area to the same coordinate system based on the identified mark The shape may be measured. Alternatively, the reference bar is provided with a plurality of marks having different shapes, and the marks included in the imaging region obtained by imaging the object to be measured including at least two marks at different locations are identified by the shapes. Then, the three-dimensional shape of the object to be measured may be measured by converting each measurement value of the imaging region into the same coordinate system based on the identified mark.

Further, in the three-dimensional shape measuring apparatus that measures the three-dimensional shape of the measurement object in the imaging region of the camera by imaging the measurement object with a camera,
A long reference bar provided with a plurality of marks arranged along the object to be measured and having a known interval;
A moving mechanism for movably supporting the camera;
Each measurement value of the imaging area obtained by imaging the object to be measured including at least two marks at different locations by the movement of the camera supported by the moving mechanism is converted into the same coordinate system based on the marks. A three-dimensional shape measuring apparatus comprising a wide-area measuring means for measuring the three-dimensional shape of the object to be measured.

  The reference bar is provided with a plurality of marks having the same shape at equal intervals, the movement mechanism includes a movement amount detection sensor for detecting the movement amount of the camera, and the wide-area measurement unit includes the movement amount. Based on the amount of movement detected by the detection sensor, the marks included in the imaging area obtained by imaging the object to be measured including at least two marks at different locations are identified, and each measurement of the imaging area is performed. It is good also as a structure which converts into the same coordinate system based on the said mark which identified the value, and measures the three-dimensional shape of the said to-be-measured object. Alternatively, the reference bar is provided with a plurality of marks having different shapes, and the wide area determination unit is included in the imaging region in which the object to be measured including at least two of the marks is captured at different locations. The mark may be identified by the shape, and the measurement value of each of the imaging regions may be converted to the same coordinate system based on the identified mark to measure the three-dimensional shape of the object to be measured. In addition, the reference bar is provided on both sides of the object to be measured, and the wide area measuring unit further measures each of the imaging regions obtained by imaging the object to be measured including at least two marks with different reference bars. It is good also as a structure which converts a value into the same coordinate system based on the said mark, and measures the three-dimensional shape of the said to-be-measured object. Furthermore, the reference bar is preferably provided with a plurality of the marks on a flat surface.

  As described above, according to the three-dimensional shape measuring method and apparatus of the present invention, a reference bar provided with a plurality of marks can be used to accurately and three-dimensionally accurately measure a large object without accumulating errors. There is an effect that it can be measured.

The best mode for carrying out the present invention will be described below in detail with reference to the drawings.
As shown in FIGS. 1-3, 1 is a to-be-measured object, for example, has a large-sized three-dimensional external shape, such as the vehicle body of a passenger car. A shape measuring device 2 that optically measures the three-dimensional shape of the object to be measured 1 is provided. The shape measuring device 2 includes a camera 4 using a CCD, a fringe projector 6, and a control device 8. The camera 4 and the fringe projector 6 are connected to the control device 8. The camera 4 and the fringe projector 6 are housed in a camera box 10.

  In the shape measuring instrument 2, the fringe projector 6 projects a plurality of gratings on the surface of the device under test 1, and the camera 4 images the lattice deformed according to the external shape of the device under test 1. And based on this deformation | transformation grating | lattice and a reference | standard grating | lattice, the control apparatus 8 measures the three-dimensional shape of the to-be-measured object 1, and obtains the measured value of a three-dimensional shape.

  In the shape measuring instrument 2, if the imaging region S by the camera 4 is wide, the resolution decreases and the measurement accuracy becomes rough, and if the imaging region S is narrow, sufficient resolution is obtained and the measurement accuracy becomes precise. Therefore, if an attempt is made to obtain the required measurement accuracy, the area of the region S imaged by the camera 4 is limited, and the partial region of the DUT 1 is measured.

  The shape measuring instrument 2 outputs a measurement value based on a three-dimensional partial coordinate system. The partial coordinate system is a coordinate system that the shape measuring instrument 2 has, and when the shape measuring instrument 2 is moved to measure another location, the partial coordinate systems of those measured values are different. Measurement values cannot be joined together to form one measurement value.

  The DUT 1 is placed on the measurement table 12, and long reference bars 14 and 16 are provided on both sides of the DUT 1 along the DUT 1. The reference bars 14 and 16 are provided with a plurality of marks M. In the present embodiment, the reference bars 14 and 16 have an elongated shape with a rectangular cross-sectional shape, and a mark M is provided on the upper flat surface, and the mark M is a planar figure. Both reference bars 14 and 16 are arranged such that the upper flat surfaces thereof are at the same height.

  The plurality of marks M may have the same shape, such as circles and squares, or may have different shapes. The plurality of marks M may be provided at equal intervals, or the intervals between the marks M may be different, but the intervals between the marks M may be known in advance.

  The measuring table 12 is provided with a moving mechanism 18, and the moving mechanism 18 includes a pair of rails 20 and 22 laid in parallel with the reference bars 14 and 16. A movable table 24 is engaged with the rails 20 and 22 so as to be movable along the rails 22 and 24, and a column 26 is erected on the movable table 24. Between the pair of rails 22, 24, a parallel movement amount detector 27 that detects the parallel movement amount of the moving table 24 is provided.

  An arm member 28 protrudes from the column 26 in a direction orthogonal to the reference bars 14 and 16. An orthogonal movement mechanism 30 is incorporated in the arm member 28, and the orthogonal movement mechanism 30 includes an orthogonal movement table 32 that is movably supported by the arm member 28. The movement direction of the orthogonal moving table 32 is orthogonal to the reference bars 14 and 16 and is configured to be able to move across the DUT 1 on the measuring table 12. A camera box 10 is attached to the orthogonal moving table 32 so that the object to be measured 1 can be imaged. Further, the arm member 28 is provided with an orthogonal movement amount detector 34 that detects an orthogonal movement amount of the orthogonal movement table 32.

  Next, a measurement procedure according to the three-dimensional shape measurement method of the present embodiment will be described with reference to the flowchart shown in FIG. 6 together with the wide area measurement process performed in the control device 8 of the three-dimensional shape measurement apparatus of the present embodiment described above.

  First, as shown in FIGS. 3 and 5, the DUT 1 is placed on the measurement table 12. Then, the moving table 24 is moved along the rails 20 and 22, and the camera box 10 is moved so that the imaging region S <b> 1 of the camera 4 is the first measurement position of the DUT 1. When a part of the device under test 1 is imaged in the first image capturing area S1, the control device 8 calculates a measurement value of the three-dimensional shape of the device under test 1 from this image data (step 100). When imaging, the imaging is performed so that the first imaging area S1 includes at least two marks M1 of the reference bar 14.

  Next, it is determined whether or not it is wide area conversion (step 110), and if it is the first imaging, it waits until the next imaging is performed, and when the next imaging is performed, the second imaging area A measurement value of the DUT 1 is calculated from the imaging data of S2. The second imaging area S2 is imaged so as to include at least two marks M1 as in the first imaging area S1. At that time, it is not necessary that at least two marks M included in each of the first imaging area S1 and the second imaging area S2 are the same, and two marks M may be different, or one Only the same mark may be used.

  When converting to the same coordinate system as these two imaging areas S1 and S2, first, the mark M1 is recognized from the imaging data of both imaging areas S1 and S2 (step 120). Based on the marks M1 of the imaging regions S1 and S2, a count for converting coordinates is calculated (step 130). This count is converted to the same coordinate system (step 140).

  As shown in FIG. 7, the X direction connecting two marks M can be recognized from at least two marks M on the reference bar 14. Further, the Z direction perpendicular to the flat surface of the reference bar 14 can also be recognized, and the Y direction perpendicular to the X direction and the Z direction can be recognized. As a result, a three-dimensional coordinate system centered on one of the two marks M can be recognized.

  Then, as shown in FIG. 8, a three-dimensional coordinate system in each of the X direction, the Y direction, and the Z direction is obtained from at least two marks M included in each of the first imaging region S1 and the second imaging region S2. They can be recognized, their distances can be recognized from each one mark M, and a count for converting the coordinates can be calculated.

  The distance of each mark M is known in advance, and when each mark M has the same shape, it is included in the imaging region S based on the amount of movement detected by the parallel movement amount detector 27. The mark M is determined. At this time, if the approximate amount of movement detected is known, it is possible to determine which mark M.

  Also, if the shape of each mark M is different, the mark M can be identified from the shape of the captured mark M without detecting the amount of movement, and the distance of each mark M is known. The count for converting can be calculated. At this time, the shape of the mark M may be different. For example, the mark M having the same shape is displayed on the reference bars 14 and 16 and a number such as a number is displayed so that each mark M can be identified. Can be similarly implemented.

  Since the coordinate conversion count is calculated based on at least two marks M included in the imaging region S, the movement by the movement mechanism 18 does not need to be parallel to the reference bars 14 and 16, as shown in FIG. Even if the first imaging region S1 and the second imaging region S2 are inclined in the X direction and the Y direction with respect to the reference bars 14 and 16, if at least two marks M are included in each, Coordinate conversion count can be calculated. In addition, even if it is tilted with respect to the Z direction, the three-dimensional coordinates are recognized on the basis of the flat surfaces of the reference bars 14 and 16, and therefore the coordinate conversion count can be calculated even if it is tilted in the Z direction due to movement.

  Even if there is no common mark M1 as in the first imaging area S1 and the second imaging area S2, the distance between the mark M1 in the first imaging area S1 and the mark M in the second imaging area S2 is Since it is known, based on this, a count for converting the coordinate system of the first imaging area S1 and the second imaging area S2 is calculated (step 130), and this count can be converted to the same coordinate system. Yes (step 140). Therefore, since the conversion of each imaging area S into the same coordinate system is performed based on the mark M, even if a plurality of imaging areas are combined, an error does not accumulate and the three-dimensional shape can be measured with high accuracy.

  In addition, as shown in FIG. 5, when the DUT 1 is large, the whole DUT 1 may not be measured only by horizontal movement. In that case, the camera box 10 is moved in the vertical direction by the orthogonal movement mechanism 30 and images are taken in the respective imaging regions S1 and S12 to obtain respective measured values. The orthogonal movement amount is detected by the orthogonal movement amount detector 34. If coordinate conversion is performed based on the orthogonal movement amount detected by the orthogonal movement amount detector 34, the plurality of imaging regions S1 and S12 can be converted into the same coordinate system.

  Furthermore, in this embodiment, the reference bars 14 and 16 are provided on both sides of the DUT 1, but one reference bar 14 and 16 may be provided on at least one side. By providing on both sides, as shown in FIG. 10, after imaging in the imaging area S1 including the mark M of one reference bar 14, the camera box 10 is moved in the orthogonal direction, and each imaging area S1, S12, Imaging is performed in S13 to obtain respective measured values. Further, by imaging in the imaging region S13 including the mark M of the other reference bar 16, it is possible to correct the orthogonal coordinate conversion based on the mark M.

  At this time, even if the moving direction of the camera box 10 is inclined with respect to the reference bars 14 and 16 by the orthogonal moving mechanism 30, the moving direction can be recognized based on the marks M of the reference bars 14 and 16. Correction of coordinate conversion in the orthogonal direction can be performed. In addition, as shown in FIG. 11, even when the camera box 10 is displaced in the Z direction during movement, the distance from both flat surfaces of both reference bars 14 and 16 can be measured. Can be corrected.

  In the present embodiment, the case where the device under test 1 is placed on the horizontal measurement table 12 and taken an image is taken as an example. However, the present invention is not limited to this, and as shown in FIG. The same can be implemented by arranging and supporting the DUT 1 on the measuring table 36 in a vertical state. In this case, the arm member 28 may be supported so as to be movable in the vertical direction along the column 26.

  The present invention is not limited to such embodiments as described above, and can be implemented in various modes without departing from the gist of the present invention.

It is explanatory drawing of the measurement by the camera of the three-dimensional shape measuring apparatus as one Embodiment of this invention. It is a front view of the three-dimensional shape measuring apparatus of this embodiment. It is a top view of the three-dimensional shape measuring apparatus of this embodiment. It is a side view of the three-dimensional shape measuring apparatus of this embodiment. It is explanatory drawing of the imaging area by the three-dimensional shape measuring apparatus of this embodiment. It is a flowchart which shows an example of the wide area measurement process performed in the control apparatus of this embodiment. It is a perspective view explaining the recognition of the coordinate based on the mark of the reference bar of this embodiment. It is explanatory drawing explaining the relationship between each imaging area of this embodiment, and the mark of a reference bar. It is explanatory drawing explaining the relationship with the mark of a reference bar when each imaging region of this embodiment inclines. It is explanatory drawing which shows the imaging area of the orthogonal | vertical direction with the reference bar of this embodiment. It is explanatory drawing which shows the inclination when imaged in the orthogonal direction with the reference bar of this embodiment. It is a front view of the three-dimensional shape measuring apparatus as other embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Object to be measured 2 ... Shape measuring instrument 4 ... Camera 6 ... Fringe projector 8 ... Control device 10 ... Camera box 12 ... Measurement stand 14, 16 ... Reference bar 18 ... Moving mechanism 20, 22 ... Rail 24 ... Moving stand 26 ... Column 27 ... Parallel displacement detector 28 ... Arm member 30 ... Orthogonal displacement mechanism 32 ... Orthogonal displacement table 34 ... Orthogonal displacement detector 36 ... Measuring platform

Claims (8)

In a three-dimensional shape measurement method for imaging a measurement object with a camera and measuring a three-dimensional shape of the measurement object in an imaging region of the camera,
A long reference bar provided with a plurality of marks with known intervals is arranged along the object to be measured, and the object to be measured is picked up in an imaging region including at least two of the marks on the reference bar by the camera. Further, the camera is moved, the camera is moved, the object to be measured is imaged in an imaging area including at least two marks at different locations, and the measured values of the imaging area in which the object to be measured is imaged are marked. A three-dimensional shape measuring method, wherein the three-dimensional shape of the object to be measured is measured by converting to the same coordinate system based on the above. The reference bar is provided with a plurality of marks having the same shape at equal intervals, and detects the movement amount of the camera, and includes at least two marks at different locations based on the movement amount. 3D of the object to be measured is identified by identifying the mark included in the imaging area where the object is imaged, and converting each measurement value of the imaging area to the same coordinate system based on the identified mark The three-dimensional shape measuring method according to claim 1, wherein the shape is measured. The reference bar is provided with a plurality of marks having different shapes, and the marks included in the imaging region obtained by imaging the object to be measured including at least two of the marks at different locations are identified by the shapes, 2. The three-dimensional shape measurement according to claim 1, wherein the three-dimensional shape of the object to be measured is measured by converting each measurement value of the imaging region into the same coordinate system based on the identified mark. Method. In a three-dimensional shape measuring apparatus that images a measurement object with a camera and measures a three-dimensional shape of the measurement object in an imaging region of the camera,
A long reference bar provided with a plurality of marks arranged along the object to be measured and having a known interval;
A moving mechanism for movably supporting the camera;
Each measurement value of the imaging area obtained by imaging the object to be measured including at least two marks at different locations by the movement of the camera supported by the moving mechanism is converted into the same coordinate system based on the marks. And a three-dimensional shape measuring apparatus comprising a wide-area measuring means for measuring the three-dimensional shape of the object to be measured. The reference bar is provided with a plurality of marks having the same shape at equal intervals, the movement mechanism includes a movement amount detection sensor for detecting the movement amount of the camera, and the wide-area measurement unit includes the movement amount. Based on the amount of movement detected by the detection sensor, the marks included in the imaging area obtained by imaging the object to be measured including at least two marks at different locations are identified, and each measurement of the imaging area is performed. 5. The three-dimensional shape measuring apparatus according to claim 4, wherein the three-dimensional shape of the object to be measured is measured by converting the value into the same coordinate system based on the identified mark. The reference bar is provided with a plurality of marks having different shapes, and the wide-area determination unit includes the marks included in the imaging region obtained by imaging the object to be measured including at least two marks at different locations. 5. The three-dimensional shape of the object to be measured is measured by identifying the shape and converting each measurement value of the imaging region to the same coordinate system based on the identified mark. The three-dimensional shape measuring apparatus described. The reference bar is provided on both sides of the object to be measured, and the wide-area measuring unit further measures each measurement value of the imaging region obtained by imaging the object to be measured including at least two of the marks with different reference bars. 7. The three-dimensional shape measuring apparatus according to claim 4, wherein the three-dimensional shape of the object to be measured is measured by converting to the same coordinate system based on the mark. The three-dimensional shape measuring apparatus according to claim 4, wherein the reference bar is provided with a plurality of the marks on a flat surface.

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