JPH0814850A - Automatic measurement system for workpiece dimension - Google Patents

Abstract

PURPOSE:To apply measures against a vibration throughout a whole process from a preliminary workpiece photographing process to a three-dimensional measurement process with a three-dimensional measurement instrument, and prevent lighting heat from affecting the measurement with the instrument at a substantial photographing process. CONSTITUTION:A stage drive mechanism 5 is provided to reciprocate a workpiece 7 between a zone for photographing an image with CCD cameras 8 and 9, and a measurement zone with a three-dimensional measurement instrument 3, and the whole of both zones is held on a vibration eliminator 1, thereby preventing the workpiece 7 from moving due to an external vibration over the period of an image pickup process to a measurement process end. As the mechanism 5 is used for reciprocating the workpiece 7, a stage travel range becomes substantially small, compared with a transfer line system. Thus, the overall size of the vibration eliminator can be reduced. in addition, the image pickup zone and the measurement zone are separated from each other and, therefore, the heat of lighting devices 4 and 10 in the image pickup zone does not affect the three-dimensional measurement.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a work size automatic measuring system suitable for automatically measuring the sizes of works of various shapes and sizes.

[0002]

2. Description of the Related Art A system for automatically measuring various works having different shapes conveyed through a conveying line has been conventionally known (for example, Japanese Patent Laid-Open No. 60-35210). In this type of system, a work is imaged by an imaging device arranged upstream of the line, the shape of the work is discriminated from the imaging result, and the measuring robot arranged downstream of the line is operated by a program corresponding to the discriminated shape. I am trying.

Rather than measurement on such a transport line,
If you try to use a coordinate measuring machine to measure the dimensions of a slightly more advanced work, not only the shape of the work but also the size, position, and posture information on the stage will be recognized during the preliminary work imaging process. You must keep it. This is because the movement path of the measuring probe of the coordinate measuring machine cannot be determined if this type of information regarding the workpiece is missing.

[0004]

However, in this type of measuring system, if the position of the work is deviated in the subsequent measuring process of the work after the information on the position of the work is obtained by the process of imaging the work in advance, The movement path of the probe of the coordinate measuring machine with respect to is improper and correct measurement becomes impossible. Particularly, depending on the environment in which the system is placed, it may be unavoidable that the system coexists with various vibration sources, and in such a case, the above-mentioned problem is likely to occur. In order to avoid this, it is conceivable to obtain the image information of the work on the surface plate of the coordinate measuring machine in which the vibration isolation device has taken measures against vibration. However, in this case, there is a problem that the heat from the light source that illuminates the work at the time of imaging adversely affects the measurement of the coordinate measuring machine.

The present invention has been made in order to solve such a problem, and it is possible to take measures against vibration in all steps from the process of imaging a work in advance to the three-dimensional measurement by a coordinate measuring machine. Another object of the present invention is to provide an automatic workpiece dimension measuring system in which the heat of illumination during the imaging process does not affect the measurement by the coordinate measuring machine.

[0006]

An automatic work size measuring system according to the present invention is based on an image pickup means for picking up an image of a work to be measured and outputting image information of the work, and image information output from the image pickup means. Image processing means for recognizing the shape and position of the work, and a coordinate measuring machine for determining the movement path of the probe with respect to the work based on the recognition result by the image processing means and measuring the dimension of the work. In the work dimension automatic measuring system, a stage on which the work is placed, a stage drive mechanism for reciprocating the stage between an imaging region by the imaging means and a measurement region by the coordinate measuring machine, and the imaging region. An illuminating means for illuminating, a stage extending from the imaging region to the measurement region, the stage drive mechanism and the coordinate measuring machine Characterized by comprising a vibration isolator for blocking the transmission of vibration from.

[0007]

According to the present invention, an image pickup area by the image pickup means,
The stage drive mechanism that moves the stage back and forth between the measurement area of the coordinate measuring machine and the whole area is held by the anti-vibration device. Can be prevented from moving. According to the present invention, since the stage drive mechanism reciprocates the stage, the moving range of the stage is significantly shorter than that of the transfer line system. Therefore, the size of the entire vibration isolation device can be reduced. Further, in the present invention, since the imaging area and the measurement area are separated, the heat of illumination in the imaging area does not affect the three-dimensional measurement.

In the present invention, since the image pickup area is separated from the measurement area, even if the illumination means for illuminating the work in the image pickup area is arranged below the stage, no thermal problem will occur. Absent. Therefore, by configuring the stage with a light transmitting member and arranging the illuminating means below the stage, the entire apparatus can be made compact, and
It is possible to obtain clear image information in which the contrast between the work and the background is emphasized by the transillumination method.

In this case, if the stage drive mechanism is composed of parallel rails and the illumination light from the illumination means arranged below passes between them, the illumination light may be blocked by the stage drive mechanism. Absent.

Further, if reference mark members are provided at least at two positions on the peripheral portion of the stage, the position of the reference mark member is recognized by the image processing means, and the position of the work piece with respect to the stage is obtained based on this, the stage On the other hand, even if the position of the image pickup device is deviated, the work position can be obtained with reference to the position of the reference mark member, so that the work position in the image processing system can be accurately obtained.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A workpiece dimension automatic measuring system according to an embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a perspective view showing a schematic configuration of this system. On the known special pneumatic type vibration isolator 1, a special frame 2 for the vibration isolator is placed, and on one side of the special frame 2 there is a coordinate measuring machine 3 and on the other side. The first illuminating device 4 is installed in each. CMM 3
Is a base 11 and a bridge-shaped arm support 13 that moves in the Y-axis direction along Y-axis guides 12 at both ends of the base 11 and connects both ends of the base 11.
Along the X-axis guide 14 of this arm support 13
The Z-axis guide 15 that moves in the axial direction and the Z-axis guide 1
5, an arm 16 that moves in the Z-axis direction along with 5, and a measurement touch signal probe 17 supported by the arm 16 are configured. Further, the coordinate measuring machine 3 includes a probe automatic exchange device 1 for probe exchange.
8 are provided.

A measuring area of the coordinate measuring machine is formed above the surface plate 11 of the coordinate measuring machine 3, and an imaging area is formed above the first illuminating device 4. A stage drive mechanism 5 is installed so as to connect these two regions. The stage drive mechanism 5 includes two parallel rails 21 that connect the surface plate 11 of the coordinate measuring machine 3 and the first lighting device 4, and a U-shaped slide table that is guided and moved by the parallel rails 21. 22 and a motor 23 for driving the slide table 22 and a screw-shaped drive shaft 24. The pallet 6 is mounted on the slide table 22. The pallet 6 constitutes a stage on which the work 7 is placed, and is composed of a transparent glass plate 31 and a frame body 32 attached to the peripheral edge of the glass plate 31. Positioning holes 33 are formed in the frame body 32, and the pallets 6 are positioned on the slide table 22 by fitting the hole 33 and the positioning bosses 34 provided on the slide table 22.

CCD cameras 8 and 9 for picking up an image of the work 7 are provided above and sideways of the work 7 arranged on the pallet 6.
Are arranged respectively. A second illumination device 10 is arranged on the opposite side of the work 7 from the CCD camera 9. The lighting devices 4 and 10 each include a case 41 in which a light source (not shown) is housed, and a semitransparent plate 42 that seals the case 41 and uniformizes the light from the light source.

FIG. 2 is a block diagram showing a signal / information processing system of this system. The image information picked up by the CCD cameras 8 and 9 is supplied to the image processing device 51, where preliminary information including a work position, a work pattern, and a work main dimension is obtained by image recognition processing. The coordinate measuring machine data processing device 52 selects a part program that defines the procedure of the three-dimensional measurement from the preliminary information, gives necessary variables to this part program, and supplies it to the controller 53.
Drive. The controller 53 uses the stage drive mechanism 5
And driving the coordinate measuring machine 3.

Next, the operation of the present system thus constructed will be described. FIG. 3 is a flowchart showing the measurement procedure of this system. In the measurement start state, pallet 6
Are arranged in an imaging area where the CCDs 8 and 9 can image. In this state, when the work 7 is carried onto the pallet 6 by a conveying means such as a human or a robot (S1), C
The work 7 is imaged by the CD cameras 8 and 9 (S
2). At this time, the illumination light from the first illuminating device 4 illuminates the work 7 from below through the parallel rails 21, the hollow portion of the slide table 22 and the glass plate 31 of the pallet 6. Since the CCD camera 8 images the work 7 from above on the side opposite to the illumination device 4, the work 7 becomes backlit and the contrast between the work and the background is reduced as shown in FIG. 4A. Enhanced and clear image information is obtained. Similarly, the image information of the side surface of the work 7 obtained by the CCD camera 9 which receives the illumination light from the second illuminating device 10 shows that the contrast between the work portion and the background is as shown in FIG. 4B. The image information is emphasized and clear.

When the image information is supplied to the image processing device 51, the image processing device 51 calculates preliminary information from the supplied image information (S3). That is, as shown in FIG. 5, the image information is binarized by the binarization unit 61, and then the edge portion of the binary image is extracted by the contour extraction unit 62. continue,
In order to improve the processing efficiency of pattern matching, the characteristic extraction unit 63 extracts a characteristic portion from the contour information, and the characteristic portion and some basic patterns stored in the basic pattern storage unit 64 are collated by the collation unit 65. It As a result, the position calculating unit 66 and the main dimension calculating unit 67 calculate the main dimensions such as the position and inner diameter, outer shape, height, and width of the work from the characteristic portions of the image based on the obtained work pattern. Preliminary information including the obtained work pattern, work position, and work main dimension is transferred to the coordinate measuring machine data processing device 52 (S4).

In the coordinate measuring machine data processing device 52, first, as shown in FIG.
Selects one of the part programs stored in the pattern-based part program storage unit 72 based on the work pattern information provided from the image processing apparatus 51 (S5). Next, the work position in the image processing coordinate system obtained by the image processing device 51 is converted into the work position in the coordinate measuring machine coordinate system by the coordinate system correction unit 73 (S
6) The work position after conversion and the work main dimension given from the image processing device 51 are stored in the variable register 74 (S7). Then, the stage drive mechanism 5 operates under the control of the controller 53, the slide table 22 is moved from the imaging region to the measurement region by a predetermined movement amount, and the work 7 is conveyed to the measurement region ( S8).

When the movement of the work 7 is completed, the part program execution section 75 is activated and the selected part program is executed. In the part program, the amount of movement of the probe, information specifying the selected probe, and the like are given as variables, and it is possible to flexibly deal with works of various sizes. The part program execution unit 75 refers to the contents of the variable register 74 at any time during the process of executing the part program, supplies a probe movement command and a necessary movement amount to the controller 53, and touches the coordinate measuring machine 3. The signal probe 17 is moved according to the part program. As a result, automatic measurement is executed (S9). Further, the part program execution unit 75 obtains the position of the work from the actual three-dimensional measurement value obtained in the process of this measurement, and replaces the work position given in advance with the work position obtained from the actual measurement value. As a result, the subsequent measurement is performed with the newly obtained accurate work position as a reference.

When the measurement is completed, the measurement data is output to an external device (S10), the stage drive mechanism 5 is activated,
The work 7 is moved from the measurement area to the imaging area (S1
1). The work 7 for which the measurement has been completed is carried out by a carrying means such as a human or a robot (S12).

According to this system, the coordinate measuring machine 3,
Since the stage drive mechanism 5 and the pallet 6 are supported by the vibration isolation device 1, it is possible to prevent the work 7 from moving due to external vibration from the start of the imaging process to the end of the measurement process. Further, since the work 7 reciprocates, it is possible to limit the length of vibration isolation to a reasonable range. Furthermore, since the imaging area and the measurement area are separated, heat from the illumination devices 4 and 10 does not affect the three-dimensional measurement.

In the above embodiments, it is assumed that the relationship between the positions of the CCD cameras 8 and 9 and the coordinate measuring machine 3 does not change, but the positions of the CCD cameras 8 and 9 themselves change. In the case of occurrence of, it becomes impossible to correctly determine the relationship between the coordinate system in the image information and the coordinate system of the three-dimensional measurement area. Therefore, for example, as shown in FIG. 7, a reference mark member 35 is provided on the frame body 32 of the pallet 6, and the position of the work 7 with the position of the reference mark member 35 as a reference is determined as the work position, whereby the image pickup means is obtained. It is possible to accurately obtain the work position regardless of the position variation of.

In order to calculate the three-dimensional position and posture of the work 7, the reference mark member 35 needs to be arranged at least at two positions which do not overlap in the XYZ axis directions. In this embodiment, the reference mark member 3 is provided at a diagonal position of the frame 32.
5 is provided. In addition, the reference mark member 35
The shape is preferably such that the pattern can be easily recognized and the position can be easily grasped accurately.
In this embodiment, since the reference sphere is formed at the tip of the reference mark member 35, there is an advantage that the pattern recognition is easy and the center position thereof is easy to be obtained. Since it is known in advance that the reference sphere is arranged at a predetermined position in both the imaging area and the measurement area, if the coordinate measuring machine 3 side also measures the position of the reference sphere. ,
The accuracy of coordinate conversion between both areas can be further improved.

[0023]

As described above, according to the present invention, it is possible to take measures against vibrations in all the steps from the image pickup process of the work in advance to the three-dimensional measurement by the coordinate measuring machine. It is possible to provide an automatic workpiece dimension measuring system in which the heat of the illumination does not affect the measurement by the coordinate measuring machine.

[Brief description of drawings]

FIG. 1 is a perspective view of a workpiece dimension automatic measuring system according to an embodiment of the present invention.

FIG. 2 is a block diagram of a signal / information processing system of the system.

FIG. 3 is a flowchart showing a measurement procedure of the system.

FIG. 4 is a diagram showing an example of image information obtained by the system.

FIG. 5 is a functional block diagram showing a configuration of an image processing device in the system.

FIG. 6 is a functional block diagram showing a configuration of a coordinate measuring machine data processing device in the same system.

FIG. 7 is a perspective view showing another configuration example of a pallet in the same system.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Vibration isolation device, 2 ... Special mount for vibration isolation equipment, 3 ... Three-dimensional measuring machine, 4 ... First illumination device, 5 ... Stage drive mechanism, 6
… Palette, 7… Work, 8, 9… CCD camera, 10
… Second lighting device.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Shinji Takahashi 1-20-1 Sakado, Takatsu-ku, Kawasaki-shi, Kanagawa Mitutoyo Co., Ltd. (72) Inventor Naoya Kikuchi 1-20-1, Sakado, Takatsu-ku, Kawasaki-shi, Kanagawa Issue Mitutoyo Co., Ltd.

Claims (4)

[Claims] 1. An image pickup means for picking up an image of a work to be measured and outputting image information of the work, and an image processing means for recognizing the shape and position of the work based on the image information output from the image pickup means. In a workpiece dimension automatic measuring system including a coordinate measuring machine that determines a movement path of a probe with respect to the workpiece based on a recognition result by the image processing means and measures the dimension of the workpiece, a stage on which the workpiece is placed. A stage drive mechanism for reciprocating the stage between the image pickup area of the image pickup means and the measurement area of the coordinate measuring machine; an illumination means for illuminating the image pickup area; A stage, a stage drive mechanism, and a vibration isolation device that holds the coordinate measuring machine and shuts off vibration transmission from the outside. Automatic workpiece dimension measurement system. 2. The stage is formed of a light transmitting member, and the illuminating unit is arranged below the stage and illuminates a work placed on the stage from below the stage. The automatic workpiece dimension measuring system according to claim 1. 3. The stage drive mechanism includes parallel rails for guiding the stage, and the illumination means illuminates the work from below the space between the parallel rails. Item 1 or 2 automatic measurement system of work dimensions. 4. The stage is provided with reference mark members at at least two locations on its peripheral portion, and the image processing means recognizes the position of the reference mark member in the imaging area, and based on this, the image processing unit is configured to perform the above-mentioned operation with respect to the stage. 4. The work size automatic measuring system according to claim 1, wherein the work position is obtained.