JP3340143B2 - Polishing tool control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control apparatus for a polishing tool, and more particularly to a control apparatus for a polishing tool for polishing and removing a defective portion on a painted surface of a work such as an automobile body.

[0002]

2. Description of the Related Art Conventionally, a coated surface of a work, such as an undercoated or intermediate-coated automobile body, is polished over its entire surface before overcoating to improve the leveling of the coated surface and the adhesion of the overcoating paint. When the polishing is performed by a robot equipped with a hand or an arm tip of the polishing tool, in order to move the polishing tool along the curved surface of the workpiece,
A technique in which an actual work is carried in, the above-mentioned polishing tool is taught along a work-painted surface, and the polishing tool is operated based on the teaching is disclosed in, for example, Japanese Patent Application Laid-Open No. 60-2084.
It is publicly known as seen in Japanese Patent Publication No.

Further, in order to inspect the painted surface of the above-mentioned work and to polish and remove the defective painting portion with a polishing tool, a technique for inspecting the painted surface is to irradiate the painted surface with light and reflect the reflected light on a screen. There has been proposed a technique of projecting and automatically detecting a surface defect from the sharpness of the projected image.

On the other hand, Japanese Patent Application Laid-Open No. 58-64517 discloses that in order to polish and correct a coating defect generated on a painted surface of the work, an operator visually inspects the conveyed work and finds out any defects found. A technique has been proposed in which a part and a defective state are input by an indicating device, respectively, and the polishing is automatically performed by a water research apparatus including a robot or the like on the downstream side.

[0005]

[SUMMARY OF THE INVENTION] Thus, in performing the polishing paint defect site of the work by the above-described polishing tools, or to store the operation pattern of the grinding tool in teaching or painted with the command by the position data Lack of
The control for polishing the recessed portion has a problem that accurate and high-quality polishing cannot be performed, and the teaching process becomes complicated.

That is, when a work is polished by a polishing tool, a good polished surface cannot be obtained unless the polishing tool is operated from a direction perpendicular to the surface of the work. Is complicated, and in the case of performing partial polishing, it is necessary to call the operation direction of the corresponding portion from a large number of teachings and perform the operation based on the operation direction.

Further, when performing based on position data,
The position in the two-dimensional image picked up by the image pickup means does not match the position of the three-dimensional work surface, and has various shifts.
Moreover, setting operation of the polishing tool from a normal direction perpendicular to the surface of the work involves a difficult process.

In view of the above circumstances, an object of the present invention is to provide a control apparatus for a polishing tool that can easily perform control including the operation direction of the polishing tool on a photographing screen.

[0009]

In order to achieve the above object, a polishing tool control device according to the present invention, as shown in FIG. The photographed image of the work B is analyzed by the three-dimensional image processing apparatus 1, and the polishing tool 50 is analyzed based on the position data.
Is used to polish a paint defect portion of the work B. The three-dimensional data of the surface shape of the work B is stored in advance, and the surface of the work B is used as an effective image range.
A model storage unit 2 for dividing and setting a plurality of image frames of a size corresponding to one set photographing screen, setting and storing a normal direction of a work surface in each image frame portion, and carrying and actually polishing Image capturing means 3 for capturing a surface image of the work B in an image frame corresponding to each image frame set in the model storage means 2 for the work B to be performed, and an image of the workpiece B captured by the image capturing means 3 Analyzing means 4 for obtaining position data of a polished portion to analyze and polish, and a polishing tool based on position data of the polished portion by the analyzing means 4 and normal data of the polished portion stored in the model storage means 2. 50
And a posture control means 5 for controlling the polishing position and posture with respect to the work surface.

[0010] In the photographing of the image pickup means 3 at the polished portion, the analysis means 4 performs the third order in the image frame.
The surface of the work B of the original data and the plane where the photographing means 3 is located
The plane located at the average value of the distances
The surface of the work B is offset from the surface
It is preferable to perform conversion correction on the position data based on the offset value .

[0011]

In the polishing tool control device as described above, three-dimensional data of the surface shape of the work is stored in advance in the model storage means of the three-dimensional image processing device, and the surface of the work in the three-dimensional data is used as an effective image. Set as a range
Was 1 divided set into a plurality of image frames of a size corresponding to the shooting screen, performs shooting order of teaching or the like, sets the perpendicular direction normal to the surface of the three-dimensional data in a portion of each image frame For a workpiece to be polished on a real line, a surface image of the workpiece is sequentially photographed by an imaging unit corresponding to the image frame of the model storage unit. The image of the work is analyzed by the analysis means, such as the surface painting state, and the position data of the polished part to be polished by the polishing tool is obtained.
The position data of the polished part is input from the analyzing means to the attitude control means, and the normal data of the polished part is called from the storage means to the attitude control means, and the attitude control means moves the polishing tool to the polished part. The polishing position and posture are controlled so that the polishing tool acts on the work surface from the appropriate polishing direction based on the normal direction, and the paint defect on the work is controlled.
A performs the position of the polishing process, the process based on the normal direction of the setting by the 3-dimensional data of the surface shape of the workpiece without performing the teaching operation for the polishing direction of setting the actual work surfaces of the grinding tool It is easy to perform and can obtain accurate and good polishing accuracy.

When the workpiece is photographed by the imaging means, the position data of the polished portion on the plane of the photographed image based on the relationship between the photographing direction and the workpiece surface shape, and the three-dimensional data of the model storage means are stored. There may be a deviation from the position data of the corresponding polishing part, but the work surface of 3D data
Is located at the average value of the distance between the
The plane is used as the reference plane, and the table
When the surface is to convert corrected position data based on the offset value you are offset, in which more accurate position data can be obtained, it is possible to improve the polishing precision.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows a schematic plan configuration of a hydroprocessing line of an automobile manufacturing plant equipped with a polishing tool control device according to one embodiment. The description will be made with reference to the front, rear, left and right directions of the vehicle body as the work B.

An automotive water processing line L is provided downstream of an intermediate coating line (not shown), and an imaging station L1, a polishing station L2, and a repair station are provided from the upstream side.
L3 and a washing station L4 are provided.

First, the imaging station L1 is provided with a pair of front and rear imaging robots R1 and R2 for photographing the surface of the work B, and the medium-painted work B is conveyed to the imaging station L1 and, for example, is moved forward. The first half of the work B is photographed by the imaging robot R1, and the second half of the work B is photographed by the imaging robot R2 behind. An image captured by a camera 43 of the imaging robots R1 and R2, which will be described later, is input to the three-dimensional image processing apparatus 1 and a defective portion of the paint is detected. Although not shown in detail, the three-dimensional image processing apparatus 1 includes a main body for performing arithmetic processing and storage, a CRT display for displaying an image, a keypad and a tablet for input operation, and the like.

In the polishing station L2, imaging robots R1, R
A polishing robot R3 of the same type as 2 is provided, and the polishing robot R3 polishes a coating defect portion, that is, a polishing portion, based on position data based on an analysis result of a captured image from the imaging station L1. In addition, the repair station L3 is provided for polishing the remaining polishing portion by the operator when the polishing robot R3 cannot polish all the coating defect portions within a predetermined line tact because the number of polishing portions is large. ing. Further, the washing station L4 is provided with a plurality of washing showers 27 and washing brushes 28 and 29, so that the work B after polishing is washed with water.

Next, an example of the mechanical structure of the imaging robots R1 and R2 and the polishing robot R3 will be described. Since each robot is basically the same type of robot and has the same structure, the imaging robot R1 in the front will be described with reference to FIG. The same reference numerals are given to the same members of each robot.

Columns 10 are erected at four front, rear, left and right corners of the imaging station L1, and beams 11 extending in the front and rear direction are fixed to the upper ends of the two left and right columns 10, respectively. At the upper end, a guide rail 12 is provided in the front-rear direction, and a movable frame 13 extending in the left-right direction across the beams 11 on both sides is provided. The engagement portions 13a with bearings at both ends of the movable frame 13 are provided with the guides. It is provided on the rail 12 so as to be movable in the front-rear direction. A ball screw shaft 14, which is driven to rotate by a servomotor (not shown), extends in the front-rear direction at the upper end of the right beam 11, and is screwed to the ball screw shaft 14 at the right end of the movable frame 13. A nut is provided, and the movable frame 13 is moved in the front-rear direction via the nut by rotating the shaft 14 with a servomotor.

On the other hand, a ball screw shaft 16 in the left-right direction, which is rotationally driven by a servo motor 15, is provided on the movable frame 13.
And a movable rail 18 having an engaging portion (not shown) slidably engaged with the guide rail 17 and a nut screwed to the ball screw shaft 16. The servo motor 15
The movable base 18 is moved in the left-right direction via the nut by rotating the shaft 16.

Further, the movable table 18 is provided with a ball screw nut 19 and a pair of rod guides 18a which are driven to rotate by a vertical servomotor. The hand holding member 22 is attached to the lower end of the guide rod 21
The hand holding member 22 is moved up and down by rotating and driving the ball screw nut 19. The hand holding member 22 includes a drive connecting portion 23 for rotating around a vertical axis by a servo motor, a driving connecting portion 24 for rotating around a horizontal axis by a servo motor, and a hand connecting portion 24 around a hand axis by a servo motor. Drive coupling 25 for rotational drive
And the hand 26 is mounted via. Further, a CCD camera 43 for imaging and a projector 42 for illumination are attached to a tip of the hand 26 by a support member 41.

In the case of the polishing robot R3, a polishing tool 50 as shown in FIG.
Is attached. The polishing tool 50 has a whetstone at the tip.
51 and an actuator for driving the grindstone 51 to vibrate in the lateral direction
52.

The imaging robots R1, R configured as described above
2 and the polishing robot R3 have six degrees of freedom of an x-axis (front-back direction), a y-axis (left-right direction), a z-axis (vertical direction), a vertical axis, a horizontal axis, and a hand axis.

Next, a control device for the imaging robots R1 and R2 and the polishing robot R3 will be described. Imaging station
A robot controller 32 for controlling the position of the imaging robots R1 and R2 is provided in L1, and a three-dimensional image processing apparatus 1 for processing an image captured by the CCD camera 43 of the imaging station L1 is provided. In addition, the polishing station L2 controls the position of the polishing robot R3 and the polishing tool.
A polishing control device 34 for controlling 50 polishing conditions is provided. The polishing control device 34 receives position data from the three-dimensional image processing apparatus 1.

Here, in order to detect a defective portion on the painted surface of the work B carried into the water laboratory line L and to obtain a polished portion, the work surface is sequentially photographed by the CCD camera 43 and an image is taken in. The teaching of the imaging robots R1 and R2 is performed using a robot CAD simulation. This teaching displays the image frame and the shooting direction vector (showing the distance and direction between the camera origin and the point on the work B) on the CRT display. Shooting points are set sequentially while outputting. And before doing this teaching,
The image processing apparatus 1 stores three-dimensional data of the surface shape of the work B in advance, and obtains an image width (capture frame) obtained by one photographing at the time of teaching by the imaging robots R1 and R2.
Of the work model image based on the three-dimensional data is sectioned so as to be sequentially arranged in the image frame, and a photographing direction is set in each image frame. Teaching is performed by setting a vector. In addition, a normal direction perpendicular to the surface of the model image at a plurality of portions of each image frame, for example, at a plurality of points on the frame line, is obtained and stored.

Subsequently, in response to the actual work B after the intermediate coating being carried into the automatic water research line L, the imaging robots R1, R2 of the imaging station L1 based on the teaching.
The operation of the workpiece B is sequentially controlled by the position of the image frame, the distance set by the shooting direction vector, and the shooting direction so that the same image frame as the image frame set on the model image is shot. This is to take a picture and capture the image. Then, a coating defect portion is detected from the input image by visual observation or sharpness, etc., and this portion is designated as a portion to be polished by the polishing tool 50 of the polishing station L2, and data for performing this polishing is output. Is what you do. The command data for the polishing robot R3 of the polishing station L2 is the three-dimensional position data of the polishing part and the normal direction data of the part. Based on this data, a predetermined polishing part is determined for the workpiece B moved to the polishing station L2. The polishing is performed by pressing the grindstone 51 of the polishing tool 50 against the surface of the polishing tool 50 from the normal direction.

Here, the processing in the simulation will be described with reference to FIGS. FIG. 5 shows an example in which three-dimensional data of a workpiece shape is created by a surface model BM when storing the three-dimensional data. The surface model BM used here is a three-dimensional patch. A grid-like intersection point a is set as a coordinate point in each planar portion, and the x, y, and z values of the coordinate point are input and surface data is stored. Is for obtaining approximate coordinates by a three-dimensional surface interpolation formula. In the case of an actual work B such as an automobile body, the surface model BM is difficult to represent the entire complex shape due to its nature. Create and represent and store model shapes.

The work surface model BM created as described above is converted into a CR on any of the xy, yz, and zx planes according to the teaching position of the imaging robots R1 and R2.
Show on the T display. For example, as shown in FIG. 6, in the case of teaching the side surface of the work, a surface model BM on the zx plane is displayed. In this surface model BM, data is set based on the coordinate origin O. Further, in the case where the surface data is set for each teaching location of the work B and for each group, a target data group is selected.

Next, an image frame F (frame) captured by the camera 43 is displayed on the CRT display with respect to the surface model BM of the work B displayed on the CRT display. This image frame F is, as described above, a CCD camera 43.
Corresponds to a range to be photographed as one photographed image, and is set as an effective image range within the image input range. Then, the surface model of the work B corresponding to the image frame F
Partition the BM and automatically generate teaching points.

The automatic generation of the teaching points is as follows.
First, at the start, the image frame F is moved to an appropriate position, for example, a position closest to the coordinate origin O, and only the first teaching is set. However, at this point, only the x and z components are set, and the y component is automatically set later. Further, a scanning direction for automatically generating a teaching point is determined. In the example of FIG. 6, x and z are scanned in the + direction. The y component of the teaching point sets a positive direction or a negative direction with respect to the work B (the negative direction in the example of FIG. 6). Further, the range in the x direction and the z direction in which teaching is performed in accordance with the size of the surface model BM is set with respective coordinate values so as to surround the outside of the model BM. Subsequently, the image frame F of the camera 43 is set in the x direction and the z direction. The image frame F is set automatically or manually by a manual operation so that the frame lines of the adjacent image frames F overlap. I do. Eventually, for those in which the image frame F is set over the entire operation range, teaching is unnecessary for the image frame F in a portion not overlapping with the surface model BM, and the image frame F to be taught is selected. However, this selection may be performed at the same time in the case of manual operation when sequentially setting the image frames F. In addition, when the image frames F are automatically set, the projected image frame F is picked, This is performed by a method such as assigning a number to the image frame F and selecting it.

By setting the image frame F, the x and z values on the work B where the center point T (see FIG. 7) of the frame F is located are the x and z points where the CCD camera 43 is located. A predetermined distance parallel to the y-axis (for example, 30
cm) x, y, z where the camera 43 is actually located
This point becomes a teaching point, and is set at the center point T of the image frame F (a shooting direction vector indicating a shooting direction and a distance).

Subsequently, the teaching point and the normal vector of the surface of the work B to which the image is to be captured are automatically set. This setting is obtained by performing the following processing for each image frame F.

First, as shown in FIG. 7, the light passes through a point b at a constant distance, for example, 1 cm, along the frame of the image frame F.
An intersection d that comes into contact with the three-dimensional surface model BM of the work B in the minus direction is determined by a line segment c parallel to the y-axis. When a fraction occurs at an end portion at a set interval, data at the four corners of the frame must be obtained. If the surface model BM is set for each group and there are multiple overlapping surface models BM, the intersection d is found for all group data, and the average value of that point is calculated later. I do. On the other hand, in the part where the frame deviates from the surface model BM, there is no intersection d with the surface model BM,
Do not count.

As shown in FIG. 8, the average value of the y-coordinates on the surface model BM is determined for the line segment c for which the intersection d has been determined as described above, and the reference plane G is set. Further, a normal vector V at an intersection d between the line segment c and the surface model BM is obtained.

The normal vector V is a unit vector,
Various methods are available for obtaining the normal vector V. For example, as shown in FIG. 9, the normal vector V is obtained using the patch-like surface model BM. That is, it corresponds to the patch-like surface model BM in FIG.
Is defined as one plane p, and a direction perpendicular to the plane p is determined and set as a normal vector V. The intersection d on the surface model BM is obtained by surface interpolation. The data of the normal vector V is stored according to a determined file format.

The location where the normal vector V is obtained may not be the portion above the frame of the image frame F.
May be determined at a predetermined location such as the image center T or the n-divided center.

The order of teaching is set for the image frame F set as described above. The setting is performed by picking an image displayed on a CRT display, for example. Will be Also,
In general, the teaching program is created for each module. For example, in the example of FIG. 6, the front fender portion (eight image frames) is set to the first module, and teaching is performed so as to sequentially shoot images. The middle door part (eight image frames) is set as the second module, and teaching is performed so as to take pictures in order, and the rear fender part (6
The image frame may be set in the third module and teaching may be performed so as to sequentially capture images.

FIG. 10 shows a correction for improving the accuracy of the position data of the image taken by the camera 43. The correction is performed on the assumption that the image frame F and the offset on the work surface model BM are used. Ask for. The offset value t is calculated from the average y-coordinate value (reference plane G) at the intersection d with the line segment c by the yz of the surface data.
The distance to the intersection d on the cross section is obtained and recorded. Then, when the work surface BM for measuring the position data of the polished portion to be polished is offset from the reference surface G with respect to the camera 43, the position on the photographing screen is shifted from the accurate position. Make corrections.

That is, when the camera 43 captures an image, the image is formed in a plane on the reference plane G where the scale factor is SF0, so that the work surface has a curved shape and is shifted from the reference plane G. When offset by t, the position data (y0, z0) photographed by the camera 43 does not match the actual position (y, z), and the scale factor SF (mm / pixel) for correcting the coincidence is corrected. The similarity conversion correction formula in ()) is as follows, where L is the distance between the camera 43 and the reference plane G.

SF = SF0 · L / (L + t) By this conversion, the exact position of the polishing portion is obtained, and this position data is sent to the control device of the polishing station L2 to move the polishing tool 50, so that accurate polishing is performed. Can be performed. In the conversion correction, scale conversion is performed for each area in accordance with the normal vector V obtained for each area obtained by subdividing each section. Similar correction is performed in the x direction.

The normal vector V and the scale conversion obtained as described above are used for controlling the attitude of the polishing tool 50 as described above. That is, an image of the work B taken by the camera 43 is taken along the taught image frame F, a coating defect portion is detected by analyzing the image, and the polished portion is positioned (x0, y0, z) in the image.
0) is obtained, and the posture of the polishing tool 50 is controlled based on the normal vector V in each region and the position data (x, y, z) corrected by the scale conversion.
Polishing is performed by pressing 50 in a predetermined polishing direction.

In the above-described embodiment, the imaging robots R1 and R2 and the polishing robot R3 have a structure in which the robots are installed and moved on the column 10 installed in the station. The camera 43 or the polishing tool 50 may be installed at the tip of the robot having the arm extended, and other types of robots can be used as appropriate.

Further, regarding the detection of a coating defect, a camera
In addition to the detection from the image taken by 43, a visual inspection of the surface of the work B is performed by an inspector, and a predetermined defect mark is placed on a paint defect portion.
The position data may be detected by the image captured in the above step, and the position data may be sent to the polishing station L2.

Further, a camera 43 for photographing a work surface image.
The photographing position, that is, the photographing direction is such that, in addition to photographing from the direction parallel to the coordinate axes as in the above-described embodiment, the teaching point is set so that photographing is performed from a direction as perpendicular to the work surface in the image frame F as possible. It may be.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a basic configuration of a polishing tool control device of the present invention.

FIG. 2 is a schematic plan view of a water polishing processing line provided with a polishing tool control device according to an embodiment of the present invention.

FIG. 3 is a sectional front view of the imaging station in FIG. 2;

FIG. 4 is a perspective view of a polishing tool.

FIG. 5 is an explanatory diagram showing a setting example of a three-dimensional surface model of a work shape;

FIG. 6 is an explanatory diagram showing an example of display of a surface model and teaching setting of an image frame.

FIG. 7 and FIG. 8 are explanatory diagrams showing examples of setting normal vectors.

FIG. 9 is an explanatory diagram showing an example of normal vector calculation.

FIG. 10 is an explanatory diagram showing correction of position data.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image processing apparatus B Work 2 Model storage means 3 Imaging means 4 Analysis means 5 Attitude control means R1, R2 Imaging robot R3 Polishing robot 43 Camera 50 Polishing tool

────────────────────────────────────────────────── ─── Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) B23Q 15/00-15/28 B24B 17/04 G05B 19/18-19/46

Claims (2)

(57) [Claims] 1. A polishing tool control device for analyzing a photographed image of a work by a three-dimensional image processing device and polishing a paint defect portion of the work by the polishing tool based on the position data, wherein In addition to storing the three-dimensional data of the shape, the surface of the work is divided and set into a plurality of image frames of a size corresponding to one shooting screen set as an effective image range, and the method of the work surface is determined at each image frame portion. A model storage means for setting and storing a line direction; and an imaging means for taking a surface image of the workpiece in an image frame corresponding to each image frame set in the model storage means for the loaded workpiece; Analyzing means for analyzing the image of the workpiece photographed by the imaging means to obtain position data of a polished part to be polished, and position data of the polished part by the analyzing means and the model storage means Control apparatus for polishing tool, characterized in that a posture control means for controlling the polishing position and <br/> orientation relative to the workpiece surface of the polishing tool on the basis of the normal line data of the polishing site being憶. 2. The image processing apparatus according to claim 1, wherein the analyzing unit is configured to detect three-dimensional data in the image frame when the image capturing unit captures the polished part.
Of the distance between the surface of the workpiece and the plane where the photographing means is located
The plane located at the value is the reference plane, and
Based on the offset value where the work surface is offset
2. The control device for a polishing tool according to claim 1, wherein the conversion correction is performed on the position data based on the position data.