JP3432706B2 - How to measure hole position - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for measuring the positions of holes such as suspension connecting holes formed in a work such as a vehicle subframe.

[0002]

2. Description of the Related Art Conventionally, when measuring a hole position, a measuring head having two cameras arranged so that their optical axes are obliquely arranged and a spot light source is attached to an operating end of a robot, and the measuring head is opposed to the hole. The work is irradiated with spot light in a state where it is positioned at a predetermined measurement position, the work is imaged by two cameras in this state, the center position of the hole on the screen of each camera is obtained by image processing, and triangulation is performed. The coordinate of the center of the hole in the spatial coordinate system is calculated by the principle of.

[0003]

In the conventional example described above, the light-dark boundary around the image of the hole appearing as a dark portion on the screen of the camera is defined as the hole edge portion of the hole, and the center of the hole is determined from the position of the hole edge portion. Although the position is sought, the light / dark boundary is blurred due to the influence of noise, etc., and the position of the detected hole edge is likely to vary, which easily causes a measurement error. At least one of the two cameras is Since the image is taken from an oblique direction,
In a hole with a depth such as a screw hole, the reflected light from the inner surface of the hole distorts the shape of the image of the hole that appears on the screen of the camera, and as a result, the position of the detected hole center shifts and It causes a measurement error of the central coordinates.

Further, since the measuring head becomes large due to the provision of the two cameras, the measuring head cannot be submerged in a place where the work is complicated, and the position of the hole formed in such a place is measured. Is difficult.

In view of the above points, an object of the present invention is to make it possible to measure the position of a hole with high accuracy and also to measure the position of a hole formed in a place where a work is complicated.

[0006]

[Means for Solving the Problems] In order to solve the above problems,
According to the work connecting portion position measuring method of the present invention ,
A second work provided on the work and connected to the first work.
A method for measuring a position of a work connecting portion for measuring a position of a connecting portion of a ark, wherein a pair of holes facing each other is formed in the connecting portion.
In the formed one, a distance measuring device that measures the distance between the measuring target and the measuring target is used, and the irradiation point of the light beam with respect to the connecting portion traverses the pair of holes. To move along the set scan line
The coordinates of a plurality of hole edge points of each hole intersecting with the scanning line are obtained based on the change in the distance between the first work and the connecting portion measured by the rangefinder during the movement. , These compound
Calculate the coordinates of the center of each hole from the coordinates of the number of hole edge points.
Between the calculated center of one hole and the calculated center of the other
Obtain the coordinates of the midpoint of the connection, and use this midpoint to identify the position of the connection.
The deviation of this midpoint from the reference position is measured as
It

Further, according to the work connecting portion position measuring apparatus of the present invention, the coordinates of two hole edge points intersecting the first scanning line are obtained and at least one of the coordinates is included.
Note that the second scanning line is tilted at a predetermined angle with respect to the first scanning line.
By moving the irradiation point along, the coordinates of at least one hole edge point intersecting the second scanning line are obtained, and the coordinates of the center of the hole are calculated from the coordinates of these hole edge points.

When the irradiation point is moved along the scanning line, the distance measured by the distance measuring device sharply increases when the irradiation point enters the hole and sharply decreases when the irradiation point departs from the hole. Therefore, the point on the scanning line where the measurement distance changes abruptly coincides with the hole edge point of the hole intersecting the scanning line. Here, the coordinates of the points on the scanning line in the plane coordinate system orthogonal to the optical axis of the rangefinder are known,
Further, since the coordinate in the optical axis direction is the distance measured by the distance measuring device, the coordinate of the hole edge point in the spatial coordinate system can be accurately measured.

[0009]

[0010]

[0011]

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which the present invention is applied to the measurement of the position of a hole for connecting a suspension formed in a subframe W as a work shown in FIG. 10 will be described.

The sub-frame W has a total of four mounting portions A1, A2, A3, A4 attached to the vehicle body at the front and rear ends of both left and right sides.
The mounting portions A1 to A4 are fastened to the vehicle body with a bolt (not shown) having a diameter smaller than the hole diameter for inserting the mounting portions A1 to A4 into the mounting holes A1a to A4a formed therein. To do.

Multi-link suspensions are attached to the left and right sides of the sub-frame W. The multi-link suspension is a suspension in which a lower arm connected to the lower part of the knuckle N and an upper arm connected to the upper part of the knuckle N are each composed of a plurality of links. Trailing link S1 extending forward and knuckle N
Lateral lower link S2 connected to the lower middle of the
And a control link S3 connected to the lower rear end of the knuckle N, and the upper arm has a laterally extending upper link S4 connected to the upper part of the knuckle N and an obliquely rearward extending link connected to the upper part of the knuckle N. The link S5 is connected to each of the connecting portions B1 to B5 provided on the side portion of the subframe. Each of the connecting portions B1 to B5 has a pair of plate portions Ba and Ba facing each other, and the end portion of each link is inserted between both plate portions Ba and Ba,
The ends of each link are pivotally attached to each connecting portion by bolts inserted into holes Bb, Bb formed in both plate portions Ba, Ba.
Further, on the outer surface of the plate portion Bd on one side of the connecting portions B1, B2, B4, B5 for the trailing link S1, the lower link S2, the upper link S4, and the leading link S5,
As shown in FIG. 8C, a nut Bc for screwing a bolt is welded. Connection B for control link S3
As shown in FIG. 9B, the hole Bb formed in each plate portion Ba of No. 3 is formed in an oval shape, and the eccentric cam displaces the bolt in the longitudinal direction of the hole Bb so that the alignment can be adjusted. ing.

By the way, the connecting portions B1 on the left and right sides
If the relative position accuracy of B5 is incorrect, the alignment cannot be accurately adjusted only by adjusting the control link S3 by the eccentric cam. Therefore, after assembling the sub-frame W, the positions of the left and right connecting portions B1 to B5 are measured in the measuring station to determine whether the relative position accuracy of the connecting portions B1 to B5 is within the tolerance. Only the sub-frame W that is within the tolerance is transferred to the next process as an acceptable product.

In the measuring station, as shown in FIGS. 1 and 2, a jig 1 for supporting the subframe W at a fixed position,
Two left and right measuring devices 2 and 2 for measuring the positions of the connecting portions B1 to B5 on the left and right sides of the subframe W are arranged.

The jig 1 is as shown in FIGS.
It is provided with four work receivers 11, 12, 13, 14 that support the sub-frame W at each of the mounting portions A1 to A4, and each mounting portion A1 to A4 is fixed to each of the work receiving receptacles 11 to 14 from above with a narrow pressure. Cylinders 110a, 120a,
Clampers 110 and 1 opened and closed by 130a and 140a
20, 130, 140 are provided. The sub-frame W is carried into a measuring station by a transfer device (not shown) in a state in which the seat surfaces of the mounting parts A1 to A4 with respect to the vehicle body are turned upside down, and the mounting device A1 is moved by a vertical movement of the transfer device. ~ A4 is for each work 1
1 to 14 are mounted.

By the way, the relative positional accuracy of the connecting portions B1 to B5 is sufficient if it is within the tolerance when the subframe W is mounted on the vehicle body. Even if the sub-frame W is slightly distorted, when the mounting portions A1 to A4 are fastened to the vehicle body, the distortion may be corrected and the relative positional accuracy of the connecting portions B1 to B5 may fall within the tolerance. On the contrary, in the subframe alone, even if the relative position accuracy of the connecting portions B1 to B5 is within the tolerance, the subframe W is distorted during mounting on the vehicle body due to the displacement of the mounting portions A1 to A4 in the height direction, and B1
The relative position accuracy of ~ B5 may not be within the tolerance. In the present embodiment, the clampers 110 to 140 tightly fix the mounting portions A1 to A4, so that the subframe W has the mounting portions A1 to A4 fastened to the vehicle body.
That is, the same state as when mounting the vehicle body is maintained, and it is possible to accurately determine whether the relative positional accuracy of the connecting portions B1 to B5 is within the tolerance when mounting the vehicle body.

The work receivers 13 and 14 for supporting the mounting portions A3 and A4 at the rear ends of the right and left sides of the subframe W are fixed on the columns 131 and 141 which are erected on the jig base 10. Front end mounting parts A on both left and right sides of W
The work receivers 11 and 12 that support 1 and A2 are mounted on the pillars 111 and 121 that are erected on the jig base 10, and the cylinders 11 are arranged on the pillars 111 and 121.
Elevating stands 112, 12 provided so as to be elevated by being guided by guide bars 112b, 122b by 2a, 122a.
It is provided on 2. Then, the work receivers 11 and 12
The height difference between the rear-end work receivers 13 and 14 and the front-end work receivers 11 and 12 is changed according to the type of the sub-frame W, and the height difference between the rear end and the front end of the vehicle body part on which the sub-frame W is mounted. I am trying to match.

Further, the work receivers 13 and 14 at the rear end are formed flat so that the mounting portions A3 and A4 can be relatively moved in the horizontal direction.
Locate pins 113 and 123 that fit into the mounting holes A1a and A2a formed in the mounting portions A1 and A2 are provided upright.
As shown in FIG. 6, the locating pins 113 and 123 have upper small diameter pin portions 113a and 123a and lower large diameter pin portion 1a.
It is formed in a stepped shape having 13b and 123b. The collars A1b, A are attached to the mounting holes A1a, A2a.
In the case of the model shown in the figure in which 2b is fitted, the heights of the work receivers 11 and 12 are lowered, and the small-diameter pin portions 113a and 12 are
3a is fitted to the collars A1b and A2b, and the mounting portion A
1 and A2 are seated on the work receiving surfaces 113c and 123c at the lower ends of the small-diameter pin portions 113a and 123a, and in the case of the model shown in the drawing in which the collar is not fitted in the mounting holes A1a and A2a, Raise the height of the work receivers 11 and 12 and attach the large-diameter pin portions 113b and 123b to the mounting holes A.
1a, A2a, the mounting portion A1, A2 is the work receiving surface 113 of the lower end of the large diameter pin portion 113b, 123b.
I am trying to sit on d and 123d. A collar with a rubber bush will be fitted later into the mounting holes A1a and A2a of the model.

The small-diameter pin portions 113a and 123a are formed to have a smaller diameter than the inner diameters of the collars A1b and A2b of the model, and the large-diameter pin portions 113b and 123b are formed to have a diameter smaller than the inner diameters of the mounting holes A1a and A2a of the model. ing. Then, the small-diameter pin portions 113a and 123a and the large-diameter pin portion 113
b and 123b are provided with a plurality of collets 113e, 123e, 113f, and 123f that can be projected and retracted outward in the radial direction, and the collet 113 is provided on the small-diameter pin portions 113a and 123a.
rods 113g and 123g having tapered portions that abut the inner end surfaces of e and 123e, and rods 113h and 1 3a that have tapered portions that abut the inner end surfaces of the collets 113f and 123f on the large diameter pin portions 113b and 123b.
23h is inserted, and both rods 113f, 113h, 123
When f and 123h are connected by pins 113j and 123j that are retained by retaining rings 113i and 123i and both rods are moved downward by lower cylinders 113k and 123k, collets 113e, 123e, 113f and 123f
Project outwardly in the radial direction of the respective pin portions 113a, 123a, 113b, 123b, and the mounting portions A1, A2 are centered with respect to the locate pins 113, 123.

The work receiver 11 is free to move in the width direction of the subframe W relative to the work receiver 12, that is, in the left-right direction, and the displacement amount of the work receiver 11 from the reference position in the left-right direction is detected. It can be detected by 114. To describe this in detail, the work receiver 11 is slidably supported by rails 115 on the elevating table 112 in the left-right direction, and the elevating table 112 is provided with detection means 114 composed of a potentiometer connected to the work receiver 11. The horizontal displacement of the work receiver 11 can be detected. In addition, the work receiver 11 is always operated by a pair of left and right pressing cylinders 116, 116 provided on the elevating table 112.
It is held at a predetermined reference position.

When setting the subframe W on the jig 1, the work receiver 11 is held at the reference position, and after setting, the constraint of the work receiver 11 by the pressing cylinders 116, 116 is released, and in this state, the locate pin 113, The collets 113e, 123e, 113f, 123f of 123 are projected to attach the mounting portions A1, A2 to the locate pins 113, 123.
To the center. At this time, if the width dimension of the sub-frame W in the left-right direction is deviated from the reference dimension, the work receiver 11 is displaced in the left-right direction from the reference position by the amount of the deviation due to the horizontal centering reaction force, and detection is performed. The displacement amount is detected by the means 114. After that, each clamper 110-140
Is closed to restrain each of the mounting portions A1 to A4.

The measuring device 2 is composed of a robot 20 and a measuring head 21 mounted on a wrist 20a, which is the operating end of the robot 20, and the measuring head 21 measures the distance as shown in FIGS. 7 (A) and 7 (B). A container 22 is attached. As the range finder 22, for example, a LK-2000 series laser range finder manufactured by Keyence Corporation can be used. The range finder 22 includes a projecting lens 22b and a bandpass filter 2 for emitting a laser beam (wavelength 670 mm) from a laser diode 22a.
2c to irradiate the object to be measured, and the reflected light is passed through the bandpass filter 22d and the light receiving lens 22e to the CCD.
Light is received by the light receiving element 22f composed of an element to measure the distance to the object to be measured, and the reference measurement distance is 30 mm.
Therefore, the distance can be measured with a resolution of 1 μm in the measurement range of ± 5 mm.

Further, in the present embodiment, a pair of distance measuring devices 22 and 22 are attached to the measuring head 21, and a pair of mirrors for bending the optical axis 22g of each distance measuring device 22 at the tip of the measuring head 21. 23 and 23 are attached, and the bending direction of one mirror 23 of the optical axis 22g of one distance measuring device 22 is opposite to the bending direction of the other mirror 23 of the optical axis 22g of the other distance measuring device 22. I am trying to become.

In the measurement, the measuring heads 21 of the measuring devices 2 on the left and right sides are sequentially moved to the connecting portions B1 to B5 on the left and right sides of the subframe W, and the pair of plate portions Ba of the connecting portions B1 to B5 are set. , Ba are inserted so that the optical axis 22g of each distance measuring device 22 bent by each mirror 23 faces the normal direction of each plate portion Ba. .

Then, the irradiation point of the laser beam irradiated from each distance measuring device 22 to each plate portion Ba via each mirror 23 is set to cross the hole Bb as shown in FIG. 8 (A). The measuring head 21 is moved by the robot 20 so as to move along the scanning line L1. The scanning line L1 is connected to each connecting portion B1.
Is set as a linear equation in a plane coordinate system orthogonal to the optical axis 22g defined based on a predetermined measurement reference position for B5 to B5, and the coordinates of each point on the scanning line L1 in the plane coordinate system are It is known.

When the irradiation point is moved along the scanning line L1, the distance measured by the range finder 22 is as shown in FIG. 8 (B).
When the irradiation point enters the hole Bb, it sharply increases to the measurement limit, and when the irradiation point deviates from the hole Bb, it sharply decreases. Therefore, from the position of the point on the scanning line L1 where the measurement distance increases sharply,
It is possible to know the coordinates in the plane coordinate system of the hole edge point La of the hole Bb on the starting end side in the scanning direction that intersects 1 and intersect the scanning line L1 from the position of the point on the scanning line L1 where the measurement distance sharply decreases. The coordinates of the hole edge point Lb of the hole Bb on the terminal side in the scanning direction in the plane coordinate system can be known. Further, the coordinates of the hole edge points La and Lb in the optical axis direction can be known from the measurement distance, and thus,
The coordinates of the hole edge points La and Lb in the spatial coordinate system can be measured. Here, the change in the measurement distance at the hole edge is very steep, so that the coordinates of the hole edge point can be accurately measured without being affected by noise or the like.

When the coordinates of the hole edge point Lb are measured, the irradiation point is moved along the second scanning line L2 passing through the hole edge point Lb inclined by a predetermined angle with respect to the scanning line L1, and the scanning distance is rapidly reduced. Hole Bb intersecting the scanning line L2 from the position of the point on the line L2
The coordinates of the hole edge point Lc of the above are calculated in the spatial coordinate system. Then, from the coordinates of the three hole edge points La, Lb, and Lc, the hole B
The coordinates in the spatial coordinate system of the center 0 of b are calculated geometrically. It is also possible to preset a plurality of scanning lines including the first scanning line L1 and measure the coordinates of four or more hole edge points to calculate the center coordinates of the hole Bb by regression processing. However, setting the second scanning line L2 starting from the hole edge point Lb as in the present embodiment is advantageous in that the time required for scanning can be shortened and the efficiency of measurement work can be improved.

By the way, the plate portion Ba to which the nut Bc is welded
In the measurement of the hole Bb, the measurement distance is equal to the plate thickness of the plate portion Ba when the irradiation point moves from the plate surface of the plate portion Ba to the end surface of the nut Bc facing the hole Bb, as shown in FIG. 8C. When the irradiation point increases within the inner diameter of the nut Bc, the measurement distance rapidly increases to the measurement limit. Therefore, scan line and nut B
The position of the intersection of c with the inner diameter circle is measured as the position of the hole edge point to obtain the center position of the inner diameter circle, and from this and the measured distance of the plate portion Ba, the inner diameter circle on the same plane as the plate surface of the plate portion Ba The center coordinates of the hole Bb are calculated and used as the coordinates of the center 0 of the hole Bb.

Then, as shown in FIG. 9 (A), the coordinates of the midpoint M of the connection between the center 0 of the hole Bb of the one plate portion Ba and the center 0 of the hole Bb of the other plate portion Ba are determined, and The displacement from the reference position of the connecting portion is measured with the midpoint M as the point representing the position of the connecting portion. When measuring the position of the connecting portion B3 for the control link S3 in which the hole Bb is formed in an oval shape, as shown in FIG. 9 (B), one plate portion Ba has one semicircular portion in the longitudinal direction of the hole Bb. Coordinates of the center of 0 and the other plate B
The coordinates of the center 0 of the other semicircular portion of the hole Bb of the a in the longitudinal direction are calculated from the coordinates of the hole edge points La, Lb, Lc intersecting the scanning lines L1, L2 set for the respective semicircular portions. , The coordinates of the midpoint M of the connection between the centers 0 and 0 are determined as the point representing the position of the connecting portion B3.

By the way, since the sub-frame W is mounted on the vehicle body so that the displacement of the mounting holes A1 to A4 can be allowed as described above, there is no problem even if the lateral width of the sub-frame W varies within the tolerance range. Absent. However, when the positions of the connecting portions B1 to B5 on the left and right sides of the subframe W are measured by the measuring device 2 on the left and right sides as described above, if there is an error in the width dimension, the trailing link tilted in the front-rear direction. When the measuring head 21 is moved to the measurement reference position with respect to the connecting portions B1 and B5 for S1 and the leading link S5, the measuring head 21 interferes with the connecting portions B1 and B5, and the tip portion of the measuring head 21 moves to the connecting portions B1 and B5. It becomes impossible to insert between the plate parts Ba and Ba, or even if it can be inserted, the tip part comes into contact with the plate part during scanning,
Measurement error may occur.

Here, the error in the width dimension of the sub-frame W is detected by the detecting means 1 as the amount of displacement from the reference position of the work receiver 11 on the left and right sides which is free to move in the left and right directions as described above.
Detected at 14. Therefore, the measurement reference position for each of the connecting portions B1 to B5 of the measuring device 2 on the left and right sides is detected by the detecting means 1.
If the displacement amount detected in 14 is corrected in the left-right direction,
The measuring head 2 is provided between the plate portions Ba of the connecting portions B1 to B5.
The tip of No. 1 can be reliably inserted, and no measurement error occurs.

Further, on the jig base 10, a pair of left and right standard devices 15 and 15 made of a U-shaped frame is provided, and the measuring device 2 measures the positions of the connecting portions B1 to B5. First, the tip of the measuring head 21 is inserted between the side plates 15a, 15a facing each other of the standard device 15, the center coordinates of the holes 15b formed in each side plate 15a are measured, and the holes 15b, 15 on both sides are measured.
The deviation of the midpoint of the line connecting the centers of b from the reference position is measured. This deviation is caused by the measuring head 2 by the robot 20.
1 due to the positioning error of each connection portion B1
The measurement reference position with respect to .about.B5 is corrected according to this deviation so that the measuring head 21 is correctly positioned with respect to each of the connecting portions B1 to B5.

When the positions of the connecting portions B1 to B5 on the left and right sides of the subframe W are measured as described above, the connecting portions B1 to B5 are measured.
It is determined whether or not the relative position accuracy is within the tolerance, the subframe W that is not within the tolerance is collected as a rejected product, and only the subframe W that is within the tolerance is conveyed to the next process. .

[0036]

As is apparent from the above description, according to the present invention, the distance measuring device can be used to measure the position of the hole with high accuracy without being affected by noise and the like, and the mirror is used. By doing so, it is possible to measure the position of the hole formed in the complicated place of the work, and by providing the distance measuring device and the mirror for each pair, the position of the hole formed on the pair of plate parts facing each other can be efficiently measured. it can.

[Brief description of drawings]

FIG. 1 is a plan view of a measuring station in which a measuring device according to the present invention is arranged.

[Figure 2] Front view of the measuring station

[Fig. 3] Plan view of the jig

[Fig. 4] Side view of the jig

5 is a front view cut along the line VV of FIG.

FIG. 6 is a vertical sectional view of a locate pin.

7A is a front view of the measuring head, and FIG. 7B is a plan view of the measuring head.

FIG. 8A is a diagram showing the relationship between scanning lines and holes, and FIG.
The figure which shows the relationship between a hole and a measurement distance, (C) The figure which shows the relationship between a hole with a nut, and a measurement distance

FIG. 9A is a diagram showing how to determine the position of a coupling portion to be measured, and FIG. 9B is a diagram showing how to determine the position of a coupling portion having an oval hole.

FIG. 10 is a perspective view of the subframe as seen from diagonally above.

[Explanation of symbols]

2 measuring devices 20 robots 21 measuring head 22 rangefinder 23 Mirror Bb hole L1, L2 scanning line La, Lb, Lc hole edge point 0 hole center

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01B 11/00-11/30

Claims (2)

(57) [Claims] 1. A first work provided on the first work.
For measuring the position of the connecting part of the second work connected to the
A method for measuring the position of a connecting portion of a link , in which a pair of holes facing each other are formed in the connecting portion.
Oite, using a range finder for measuring the distance between the measuring object with light emitting and receiving for the measurement object, so that the irradiation point of the light beam with respect to connecting portion said range finder traverses each said pair of holes Each hole is moved relative to the first work piece so as to move along the set scanning line, and each hole intersects the scanning line based on the change in the distance between the first work and the connecting portion measured by the distance measuring device during the movement. obtains a plurality of coordinates of Anaenten of calculating the center coordinates of each hole from the plurality of hole edge point coordinates
However, the calculated center of one hole of the connecting part and the calculated
Obtain the coordinates of the midpoint of the line connecting to the center, and use this midpoint as the point that represents the position of the connection,
A method for measuring a position of a work connecting portion , which comprises measuring a deviation from a quasi-position . 2. The coordinates of two hole edge points intersecting with the first scanning line are obtained, and one of the coordinates is included,
Second scan tilted by a predetermined angle with respect to the first scan line
By moving the irradiation point along the line, the coordinates of at least one hole edge point intersecting the second scanning line are obtained, and the coordinates of the center of the hole are calculated from the coordinates of these hole edge points. The method for measuring the position of the work connecting portion according to claim 1.