JP2005172610A - Three-dimensional measurement apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To permit an operator to understand the measurement position by a displacement gauge, even when an imaging means is not disposed coaxially with the displacement gauge. <P>SOLUTION: An image P1 of a work imaged by a CCD camera 34 is displayed on a CRT. A measurement position mark M1 indicating the position of the measurement point by a laser probe 35 is displayed on the image P1 of the work. When the switching to the measurement of the laser probe 35 is performed, the display image is changed so that the mark M1 is at the center of the screen of the CRT. The display position of the mark M1 is changed on the basis of position calibration data between the CCD camera 34 and the laser probe 35 and the detection output of an XYZ axis encoder. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention measures the three-dimensional shape of the workpiece from the image of the object to be measured (work) captured by a CCD camera or the like, and the displacement of the measurement point on the workpiece by a displacement meter such as a laser displacement meter or touch probe. The present invention relates to a three-dimensional measuring device to be detected.

An image measuring machine, which is one of the three-dimensional measuring apparatuses, takes an image of an object to be measured with a CCD camera or the like, and measures the contour shape or the like (XY direction) of a workpiece based on this image, and the CCD. The displacement in the height direction (Z direction) is also measured based on a signal from the focus control unit of the camera. However, measurement in the Z direction cannot be performed at high speed and with high accuracy only by such focusing control. For this reason, an image measuring machine provided with a displacement meter such as a laser displacement meter for detecting the displacement of a measurement point on the workpiece in addition to a CCD camera for measuring an image is known, for example, from Japanese Patent Application Laid-Open No. 2003-122867. In the apparatus disclosed in Patent Document 1, an observation CCD camera for observing a workpiece at the time of measurement by a laser probe in addition to a CCD camera for image measurement is separately arranged coaxially with the laser probe. Look at the camera image and align the laser probe.
Japanese Patent Laid-Open No. 11-351841 (pages 2 and 3, FIGS. 1-2, etc.)

However, there are cases where such an observation CCD camera cannot be arranged coaxially with the laser probe due to some other reason in structure. When it cannot arrange | position coaxially, since the center position of the image of a CCD camera and the position of a laser probe do not correspond, the problem that the position of a laser probe becomes difficult to understand for an operator arises. Even if a CCD camera can be arranged, if there is a separate CCD camera for image measurement, it is not economically and functionally preferable to have a CCD camera for observation in addition to this. That is, preparing an observation CCD camera having a resolution as high as that of an image measurement CCD camera leads to an increase in the cost of the entire measuring instrument. On the other hand, if an observation CCD camera having a low resolution is used, the measurement point of the laser probe 35 cannot be specified accurately, and high-precision height measurement cannot be performed.
The present invention has been made in view of such problems, and provides a three-dimensional measurement apparatus that allows an operator to understand a measurement position by a displacement meter without arranging an imaging means coaxially with the displacement meter. For the purpose.

To achieve the above object, a three-dimensional measuring apparatus according to the present invention includes an imaging unit that images a workpiece, a displacement meter that detects a displacement of a measurement point on the workpiece, and a position between the imaging unit and the displacement meter. Moving means for moving the imaging means and the displacement meter relative to the workpiece in a measurement three-dimensional space while maintaining a constant relationship;
Movement amount detection means for detecting the movement amount by the movement means, storage means for storing positional relationship information indicating the positional relationship, the image of the workpiece imaged by the imaging means, and the position of the measurement point of the displacement meter Display means for displaying a measurement point position mark indicating, and a display for changing the display position of the measurement point position mark with respect to the image of the workpiece based on the movement amount and the positional relationship information obtained by the movement amount detection means And a control means.

  According to the present invention, the positional relationship information indicating the positional relationship between the imaging unit and the displacement meter is stored in the storage unit. The display control means changes the display position of the measurement point position mark with respect to the image of the workpiece based on the movement amount detected by the movement amount detection means and the positional relationship information. Therefore, the operator can understand the measurement position by the displacement meter without arranging the imaging means coaxially with the displacement meter.

Preferred embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a perspective view showing an overall configuration of a non-contact three-dimensional measuring apparatus according to an embodiment of the present invention. This apparatus includes a three-dimensional measuring machine 1 having a non-contact image measuring function and a non-contact displacement measuring function, and a computer system 2 that drives and controls the three-dimensional measuring machine 1 and executes necessary data processing. It is configured.

  The three-dimensional measuring machine 1 is configured as follows. That is, a measurement table 13 on which the workpiece 12 is placed is mounted on the gantry 11, and this measurement table 13 is driven in the Y-axis direction by a Y-axis drive mechanism (not shown). Support arms 14 and 15 extending upward are fixed to the center of both side edges of the gantry 11, and an X-axis guide 16 is fixed so as to connect both upper ends of the support arms 14 and 15. An imaging unit 17 is supported on the X-axis guide 16. The imaging unit 17 is driven along the X-axis guide 16 by an X-axis drive mechanism (not shown). The computer system 2 includes a computer 21 that controls measurement information processing and various controls, a keyboard 22 that inputs various instruction information, a joystick box 23 and a mouse 24, a CRTCRT 25 that displays a measurement screen, an instruction screen, and measurement results, and measurement results. And a printer 26 for printing out the image.

  The inside of the imaging unit 17 is configured as shown in FIG. That is, the slider 31 is provided so as to be movable along the X-axis guide 16, and the Z-axis guide 32 is fixed to the slider 31 integrally. A support plate 33 is provided on the Z-axis guide 32 so as to be slidable in the Z-axis direction. The support plate 33 is provided with a CCD camera 34 as an imaging means for image measurement, and a laser probe as a non-contact displacement meter. 35. As a result, the CCD camera 34 and the laser probe 35 can move simultaneously in the three axial directions of X, Y, and Z while maintaining a fixed positional relationship. An illumination device 36 for illuminating the imaging range is added to the CCD camera 34. In the present embodiment, the CCD camera 34 is used not only for image measurement but also for confirming the imaging range at the time of measurement by the laser probe 35. The laser probe 35 is supported by a vertical movement mechanism 40 for retracting the laser probe 35 when the imaging unit 17 is moved, and a rotation mechanism 41 for adapting the directivity of the laser beam to an optimum direction. .

  FIG. 3 is a diagram showing details of the laser probe 35. The light emitted from the semiconductor laser 51 passes through the beam splitter 52 and the quarter-wave plate 53 and is then converted into a parallel light beam by the collimator lens 54 and passes through the mirrors 55 and 56 and the objective lens 57 to measure the workpiece 12. To form a light spot. The light reflected from the measurement unit of the workpiece 12 follows the reverse path of the mirrors 56 and 55, the collimating lens 54 and the quarter wavelength plate 53, is reflected by the beam splitter 52, and is divided into two parts by the edge mirror 58. . The light divided vertically is detected by the two-divided light receiving elements 59 and 60 arranged vertically.

  The detection circuit 61 outputs a signal corresponding to the amount of deviation from the focal position of the objective lens 57 to the measurement surface 62 of the workpiece 12 based on the output signals from the two-divided light receiving elements 59 and 60. The servo circuit 63 outputs a drive signal for driving the objective lens 57 to the drive mechanism 64 based on the detection output of the detection circuit 61. When the objective lens 57 moves up and down, the movable member 67 of the displacement detector 66 moves with respect to the fixed member 68. This movement amount is output as a displacement amount.

  FIG. 4 is a block diagram of the entire apparatus showing the configurations of the coordinate measuring machine 1 and the computer system 2 in more detail. In the three-dimensional measuring machine 1, the image signal obtained by imaging the workpiece 12 with the CCD camera 34 for image measurement is converted into multivalued image data by the A / D converter 71 and then supplied to the computer 21. The Illumination light necessary for imaging by the CCD camera 34 is given by the illumination control unit 74 controlling the illumination device 36 based on the control of the computer 21. A displacement amount signal obtained from the laser probe 35 is supplied to the computer 21 via the A / D converter 76. Then, the imaging unit 17 including these is driven in the XYZ axis direction by an XYZ axis driving unit 77 that operates based on the control of the computer 21. The position of the imaging unit 17 in the XYZ axis direction is detected by the XYZ axis encoder 78 and supplied to the computer 21.

  On the other hand, the computer 21 has a central control CPU 81, a multi-value image memory 82 connected to the CPU 81, a program storage unit 83, a work memory 84, interfaces 85, 86, 88, and a multi-value image memory. And a display control unit 87 for displaying the multi-valued image data stored in 82 on the CRT 25. The multi-value image data stored in the multi-value image memory 82 is displayed on the CRT 25 by the display control operation of the display control unit 87.

On the other hand, operator instruction information input from the keyboard 22, joystick 23 and mouse 24 is input to the CPU 81 via the interface 85. Further, the CPU 81 captures the displacement detected by the laser probe 35, XYZ coordinate information from the XYZ axis encoder 78, and the like. The CPU 81 executes various processes such as stage movement by the XYZ axis driving unit 77 and calculation processing of measured values based on the input information, the operator's instructions, and the program stored in the program storage unit 83. The work memory 84 provides a work area for various processes of the CPU 81. As will be described later, position calibration data indicating the positional relationship between the CCD camera 34 and the laser probe 35 is also stored in the work memory 84.
Measurement values of image measurement by the CCD camera 34 and height measurement by the laser probe 35 are output to the printer 26 via the interface 86. The interface 88 is for converting CAD data of the work 12 provided from an external CAD system or the like (not shown) into a predetermined format and inputting it to the computer system 21.

  The measurement data of the image measurement in the X and Y directions based on the CCD camera 34 and the measurement data of the height measurement by the laser probe 35 are synthesized based on the position calibration data between the CCD camera 34 and the laser probe 35, This synthesized data becomes the measurement data of the workpiece 12. A specific method for obtaining the position calibration data will be described.

  In this embodiment, in order to obtain position calibration data between the CCD camera 34 and the laser displacement meter 35, a flat calibration jig 100 is placed on the measurement table 13 as shown in FIG. 5A is a plan view of the calibration jig 100, and FIG. 5B is a side view. As shown in the figure, the calibration jig 100 has a trapezoidal pattern 102 formed of a light reflector such as a metal film on a substrate 101 so as to fall within the field of view of the CCD camera 34 as a reference pattern. The trapezoidal pattern 102 has a sharp edge and is formed with a minute height h in the measurement range of the laser probe 35. The trapezoid pattern 102 has two non-parallel sides, that is, a straight line segment between A1 and A2. L1 and a straight line segment L2 between B1-B2. The calibration data is obtained as follows by measuring these line segments L1 and L2 with the CCD camera 34 and the laser probe 35 which are two optical side length devices.

  If the jig 100 is imaged by the CCD camera 34 and image processing is performed using well-known edge detection, the two line segments L1 and L2 can be obtained. In addition, the laser probe 35 performs X-direction scanning at two different points on the Y axis, and similarly, two line segments L1 and L2 can be obtained by edge detection and simple calculation. Now, the measurement coordinates of the CCD camera 34 and the laser probe 35 are (X1, Y1) and (X2, Y2), respectively, as shown in FIG. 6, and the deviation of these center coordinates, that is, the offset value is (x0, y0). ), The equation obtained by the CCD camera 34 for the line segment L1 and the equation obtained by the laser probe 35 have the following relationship:

[Equation 1]
y = a ₁₁ x + b ₁₁
y−y0 = a ₁₂ (x−x0) + b ₁₂

    Similarly, the equations obtained by the CCD camera 6 and the laser displacement meter 7 for the line segment L2 are expressed by the following equation (2).

[Equation 2]
y = a ₂₁ x + b ₂₁
y−y0 = a ₂₂ (x−x0) + b ₂₂

  In the measurement by the CCD camera 34 and the laser probe 35, as described above, after one measurement is performed, the measurement system is moved in the X and Y axis directions, and the other measurement is performed. In this case, the relative positional relationship of the above equations (1) and (2) can be obtained in consideration of the amount of movement in the X and Y horizontal planes of the measurement system between two measurements.

The slope of the line segments L1, L2, regardless of the offset of the coordinate centers of the two measurement systems, because obtained equal between CCD camera 34 and the laser probe 35, in Equations 1 and _{2, a 11 = a 12 (} = a ₁ ), a ₂₁ = a ₂₂ (= a ₂ ). By substituting these into Equations 1 and 2 and performing an operation for erasing x and y, the offset values (x0, y0) of the two central coordinates are obtained as shown in Equation 3 below. The offset value (x0, y0) is stored in the work memory 84 as position calibration data between the CCD camera 34 and the laser probe 35.

[Equation 3]
_{x 0 = {(b 21 -b} 22) - (b 11 -b 12)} / (a 1 -a 2)
_{y 0 = {a 1 (b} 21 -b 22) -a 2 (b 11 -b 12)} / (a 1 -a 2)

  By using the obtained position calibration data, the measurement of the two-dimensional shape of the workpiece 12 is performed by the CCD camera 34, the height measurement of each part of the workpiece 12 is performed by the laser probe 35, and the positions of the measurement data of both are measured. The three-dimensional shape of the workpiece 12 can be measured while accurately obtaining the correlation. When the height is measured by the laser probe 35, the measurement position by the laser probe 35 is determined by using the image data acquired by the CCD camera 34 that is not arranged coaxially with the laser probe 35 and the position calibration data. Display on CRT 25.

Next, the operation of the coordinate measuring machine 1 in the height measurement by the laser probe 35 will be described with reference to FIGS. 8 and 9 along the flowchart shown in FIG.
First, as shown in FIG. 8, an image P1 including a measurement point S1 to be measured by the laser probe 35 is captured and acquired by the CCD camera 34 (S1 in FIG. 7). The obtained image P1 is temporarily stored in the multi-valued image memory 82. Further, the CPU 81 reads the position calibration data stored in the work memory 84. As shown in FIG. 9A, the image P1 is displayed on the CRT 25. At this time, the measurement position mark M1 indicating the measurement point S1 is shifted from the center of the image P1 by the position calibration data. Is displayed (S2).

  Next, when switching to measurement by the laser probe 35 is executed (S3), the display screen is displayed so that the position of the measurement position mark M1 is at the center of the screen of the CRT 25 as shown in FIG. Change (S4). When the laser probe 35 further moves from this state (S5), the amount of movement is detected by the XYZ-axis encoder 78, and a detection signal of the encoder 78 is input to the CPU 81. The CPU 81 transmits a control signal based on the amount of movement of the laser probe 35 to the display control unit 87, and the display control unit 87 changes the relative display position of the measurement position mark M1 on the image P1 based on this control signal. (S6) to display that the measurement point of the laser probe 25 has moved. Here, as shown in FIG. 9C, the measurement position mark M1 does not move from the center of the screen, and the image P1, which is the background, moves. In addition, as shown in the figure, an arrow Y1 indicating the locus of movement of the measurement point S1 may be displayed. Further, as shown in FIG. 10, the measurement position mark M <b> 1 may be moved without moving the image P <b> 1. Also at this time, the arrow Y1 indicating the locus can be displayed.

  When the laser probe 35 moves outside the image P1, the image of the workpiece 12 is acquired again at that position, and the measurement position mark M1 indicating the measurement point S1 is displayed based on the image. Also at this time, the display position of the measurement position mark M1 is determined based on the position calibration data stored in the work memory 84.

  As mentioned above, although embodiment of invention was described, this invention is not limited to these, A various change, addition, etc. are possible in the range which does not deviate from the meaning of invention. For example, in the above-described embodiment, the laser probe 35 that measures the height of one measurement point is used as a displacement meter. However, the measuring machine uses a scanning laser probe that continuously measures a large number of measurement points. Also, the present invention can be applied. The present invention can also be applied to a measuring machine that uses a touch probe or the like instead of a laser probe as a displacement meter.

1 shows an overall configuration of a non-contact three-dimensional measuring apparatus according to an embodiment of the present invention. The internal structure of the imaging unit 17 shown in FIG. 1 is shown. The detailed block diagram of the laser probe 35 shown in FIG. 1 is shown. It is a block diagram of the whole apparatus which showed the structure of the coordinate measuring machine 1 and the computer system 2 in detail. The structure of the calibration jig 100 is shown. The calculation method of position calibration data is shown. 4 is a flowchart showing a procedure for executing measurement by a laser probe 35; A state in which an image P1 of the workpiece 12 in the case of performing measurement by the laser probe 35 is shown. The change of the display screen of CRT25 in the case of performing the measurement by the laser probe 35 is shown. Another example of the display screen of the CRT 25 when performing measurement by the laser probe 35 is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Three-dimensional measuring machine, 2 ... Computer system, 11 ... Mount, 12 ... Workpiece, 13 ... Measurement table, 14, 15 ... Support arm, 16 ... X axis Guide, 17 ... Imaging unit, 21 ... Computer, 22 ... Keyboard, 23 ... Joystick box, 24 ... Mouse, 25 ... CRT display, 26 ... Printer, 34 ... -CCD camera, 35 ... laser probe, 36 ... illumination device, 40 ... vertical movement mechanism, 41 ... rotation mechanism, 51 ... semiconductor laser, 52 ... beam splitter, 53 ... -1/4 wavelength plate, 54 ... Collimating lens, 55, 56 ... Mirror, 57 ... Objective lens, 58 ... Edge mirror, 59, 60 .. Two-divided light receiving element 61... Detection circuit 63. Servo circuit 64. Drive mechanism 66. Displacement detector 67. Movable member 68. 71 ... A / D converter, 74 ... illumination control unit, 76 ... A / D converter, 77 ... XYZ axis drive unit, 78 ... XYZ axis encoder, 81 ... CPU 82 ... Multi-valued image memory, 83 ... Program storage unit, 84 ... Work memory, 85, 86, 88 ... Interface, 87 ... Display control unit, 100 ... Calibration treatment 101, substrate, 102, trapezoid pattern

Claims (4)

Imaging means for imaging a workpiece;
A displacement meter that detects the amount of displacement of the measurement point on the workpiece;
Moving means for moving the imaging means and the displacement meter relative to the workpiece in a measurement three-dimensional space while keeping a positional relationship between the imaging means and the displacement meter constant;
A movement amount detection means for detecting a movement amount by the movement means;
Storage means for storing positional relationship information indicating the positional relationship;
Display means for displaying an image of the workpiece imaged by the imaging means and a measurement point position mark indicating the position of the measurement point of the displacement meter;
Display control means for changing the display position of the measurement point position mark with respect to the image of the workpiece based on the movement amount obtained by the movement amount detection means and the positional relationship information; measuring device.   The three-dimensional measuring apparatus according to claim 1, wherein the positional relationship information is obtained by calculating and storing the positional relationship based on a measurement result obtained using a calibration jig.   The display control means makes the display position of the image of the workpiece unchanged when the displacement meter moves, while obtaining the display position of the measurement point position mark on the image of the workpiece by the movement amount detection means. The three-dimensional measuring apparatus according to claim 1, wherein the three-dimensional measuring apparatus changes based on the movement amount. The display control means makes the display position of the measurement position mark unchanged when the displacement meter moves, while changing the display position of the image of the workpiece based on the movement amount obtained by the movement amount detection means. The three-dimensional measuring apparatus according to claim 1.

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