JPH01207610A - Measuring method for reference position of vehicle body component - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a reference position measuring method for measuring and determining whether or not a reference position such as a hole position in a vehicle body part is at a predetermined position.

(Prior Art) In general, there are three methods for automatically measuring and determining whether or not a reference position such as a hole position is at a predetermined position and whether or not the size thereof is a predetermined size. Dimensional measuring devices are well known, but these three-dimensional measuring devices are usually large and expensive, and also have the disadvantage of not being able to measure reference positions inside parts, etc., so they are not suitable for automobiles. It is not used much on production lines or inspection lines.

On the other hand, in order to solve the problems of such three-dimensional measuring devices, recently, multi-joint robots have been developed in which a laser distance meter or a stylus distance meter is provided at the tip. The method for measuring a reference position using an articulated robot with a distance meter at the tip is, for example, when measuring the position of a hole in a car body part, first, the robot is taught the position of the hole to be measured in the car body part that becomes the reference. conduct.

At this time, the distance to the hole and the size of the hole are measured using a distance meter, and the measurement results are stored as basic data. After that, the distance meter at the tip of the robot is automatically positioned relative to the vehicle body part to be measured, and the distance meter measures the distance to the hole and the size of the hole, and this measurement result is compared with the basic data above. The quality of the product is determined based on the deviation between the two.

(Problem 8 to be solved by the invention) However, in the above-mentioned conventional reference position measurement method using an articulated robot, when a laser distance meter is used as a distance meter, the center of the laser distance meter is completely aligned with the center of the hole during robot teaching. For example, you need to set it to match
There is a problem that robot teaching is extremely troublesome and time-consuming.

On the other hand, when a stylus distance meter is used as a distance meter, there is a problem in that the displacement of the hole position can only be measured by the size of the tapered portion of the stylus, and the measurement range of the positional displacement is extremely narrow.

Additionally, if it is determined that the hole position in a car body part is misaligned, it is necessary to display the extent of the deviation in original drawing coordinates (3-axis orthogonal coordinates used in the design of car body parts). However, since the coordinates that indicate the operating state of an articulated robot do not correspond to the original coordinates as in the case of a three-dimensional measuring device, the deviations in the original coordinates are calculated using a complex calculation called coordinate transformation. As a result, it is necessary to use a computer with a large capacity, which increases the cost and increases the measurement time.

The present invention has been made in view of these points, and its purpose is to provide a camera at the tip of an articulated robot in place of a conventional range finder, thereby quickly and reliably measuring a reference position. It is an object of the present invention to provide a reference position measuring method that can measure positional deviations over a wide range, and that can easily display deviations in original coordinates.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a reference position for measuring the reference position of vehicle body parts using an articulated robot and a camera provided at the tip of the robot. The measurement method has the following configuration.

First, a mark indicating the axial direction and unit length based on the original drawing coordinate axes is placed around the reference position of the car body part to be measured, and this mark is used when the camera is positioned by robot teaching. Read the coordinates and store them as basic data. After that, with the camera automatically positioned by the robot relative to the car body part to be measured, the reference position of the car body part is read on the camera coordinates, and this read reference position of the car body part is compared with the above basic data to determine the camera coordinates. Calculate the deviation at
This deviation is corrected based on the axial direction and unit length of the mark to determine the deviation in the original coordinates.

(Function) With the above configuration, in the present invention, during robot teaching, the camera at the tip of the articulated robot is aligned with the reference position of the vehicle body part that is the reference, and the measurement is performed around the reference position. It is necessary to read the marked mark on the camera coordinates, but when reading the mark with this camera, it is sufficient that the center on the camera coordinates and the mark approximately coincide, and it is not necessary to read the mark on the camera coordinates. Since the center and the reference position do not have to coincide completely, robot teaching can be performed more easily and quickly.

In addition, even if the reference position of the body part to be measured deviates from the predetermined position (the position facing the camera that is automatically positioned by the robot), the range that can be read by the camera is quite wide, so the measurement range of position deviation can also be adjusted. It will be significantly expanded.

Furthermore, when the positional deviation of the reference position is displayed in the original coordinates, the deviation indicating the amount of positional deviation in the original coordinates requires complex coordinate conversion calculations between the robot coordinates indicating the operating state of the articulated robot. Instead, it can be easily determined by correcting the deviation in camera coordinates based on the axial direction and unit length corresponding to the original coordinates of the mark read by the camera.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIGS. 2 and 3 show a schematic configuration of an apparatus used to carry out a reference position measuring method according to an embodiment of the present invention. The reference position measuring method of this embodiment measures and determines whether various holes such as bolt holes formed in the automobile body are in predetermined positions and whether the holes are of a predetermined size. It is something.

In FIGS. 2 and 3, reference numeral 1 denotes a surface plate, to which a reference body or a body 2 to be measured is carried from a conveyor (not shown) for measurement. After measurement, the body 2 is carried out by a conveyor. 3 is an articulated robot installed on both sides of the surface plate 1, and the articulated robot 3 is
is provided so as to be movable on rails 4.4 along the surface plate 1, and the body 3a is rotatable around a vertical axis, and each joint (the joint between the body 3a and the shoulder 3b, the shoulder 3b and A joint portion between the arm 3c and a joint portion between the arm 3c and the hand 3d) is provided so as to be bendable. A camera 5 is provided on the hand 3d, which is the tip of the articulated robot 3. Reference numeral 6 denotes a control/processing means comprising a computer that controls the operations of the articulated robot 3 and the camera 5 and processes images read by the camera 5, and the control/processing means 6 includes a printer. A device 7, a monitor display device 8, etc. are connected.

Next, a method of measuring the hole position in the body 2 using the above-mentioned device will be explained with reference to FIG.

First, a reference body 2 was created based on the original car body design drawing.
Marks indicating two axial directions among the three axial directions of the original coordinates and the unit length are applied to each measurement hole to be measured (Sl). This mark is written on a transparent film and pasted on each measurement hole of the reference body 2, or directly attached by marking. Further, angle information of each measurement hole with respect to the reference plane is obtained from the original design drawing (S2). The angle information here means, in detail, as shown in FIG. An angle ψ with respect to a plane passing through the direction axis WL and the body longitudinal direction axis TL, and an angle φ with respect to a plane passing through the body width direction axis BL and the body longitudinal direction axis TL, and among these three angles θ, ψ, and φ, The two angles are taken as angle information for each measurement hole.

In addition, the 4th v! In J, each measurement hole Ml, H2,・
・・The unit length of the body vertical direction axis WL is a cross sign (×), and the unit length of the body longitudinal direction axis TL is a cross sign surrounded by a single circle. The unit length of the body width direction axis BL is indicated by a cross symbol surrounded by a double circle.

Subsequently, the reference body 2 with the above-mentioned marks is carried in and placed on the surface plate 1 and positioned (S3), and then robot teaching is started (S4).

During this robot teaching, the camera 5 at the tip of the articulated robot 3 is positioned perpendicular to each measurement hole at an appropriate distance approximately at the center of the measurement hole, and the monitor display device 8 The positioning is corrected using the camera monitor displayed on the screen (S5). When this positioning is completed, the vicinity of the measurement hole is photographed and read by the camera 5 (S6), and this is stored as basic data in the storage section of the control/processing means 6 (S7). In reading the vicinity of the measurement hole, the position and size of the measurement hole are read in the camera coordinates, and the two axial directions of the original coordinate and its unit length are read from the mark placed near the measurement hole. In addition to storing the basic data (S7), robot teaching data for the measurement hole is stored as teaching data in the storage section of the control/processing means 6 (S8).

In order to position the camera 5 during robot teaching, it is sufficient that the center on the camera coordinates approximately coincides with the mark, and the distance between the camera 5 and the measurement hole can be corrected over a fairly wide range by focusing the camera 5. Compared to conventional laser rangefinders, where the center of the rangefinder and the center of the measurement hole must be perfectly aligned and the distance between them must be set to a predetermined distance for positioning. Positioning work, and eventually robot teaching work, can be performed easily and quickly.

At the stage where the basic data and teaching memory regarding one measurement hole are stored, it is determined whether the number of measurements N is equal to the total number of measurement holes Nt (S9), and if this determination is NO, the number of measurements N is I counted up one (
After S10), continue robot teaching for the next measurement hole.

Then, when the number of measurements N becomes equal to the total number of measurement holes Nt (when the determination in step S9 is YES), the robot teaching is ended (S11). In addition, control and
The processing means 6 inputs the angle information of each DI fixed hole previously obtained in step S2 (512), and stores this angle information as basic data in addition to the data read by the camera 5 for each measurement hole (S13). ). Of these basic data, the position and size of each measurement hole in camera coordinates, the axial direction of the drawing coordinates of each measurement hole read from the mark, and the camera magnification found from the unit length of the mark are then calculated using the printer. Printed by the device 7 and displayed on the monitor by the monitor display device 8 (814, 515)
, ends the measurement for the reference body 2 (S16). After the above robot teaching and measurement of the reference body are completed, the reference body 2 is carried out from the surface plate 1 (S1?-
).

Next, after carrying in and placing the body 2 to be measured on the surface plate 1 and positioning it (S21), the articulated robot 3 is switched from the teaching side to the playback side and measurement for the measurement hole of the measurement body 2 is started. (S22). In this measurement, the camera 5 at the tip of the articulated robot 3 automatically moves to the measuring body 2 by the playback operation of the articulated robot 3.
(S24), and at that position, the camera 5 photographs the vicinity of the measurement hole of the 1TPI constant body 2 and reads the position and size of the measurement hole on the camera coordinates (S24). 24). At this time, even if the measurement hole of the measurement body 2 is shifted from the center position of the camera coordinates, that is, the reference position corresponding to the measurement hole of the reference body, the camera 5
Since the range that can be read is quite wide, the measurement range of positional deviation can be greatly expanded.

Then, the information read by the camera 5 (the position and size of the measurement hole on the camera coordinates) is stored in the control/processing means 6. The position and size of the measurement hole on the camera coordinates of the reference body read by are compared with the position and size of the measurement hole on the camera coordinates, and the deviation of the measurement hole on the camera coordinates (that is, the amount of positional deviation and the size difference) is calculated (S25). Furthermore, by performing a predetermined conversion on the deviation of the measurement hole at the camera coordinates, the deviation of the measurement hole at the original coordinates is calculated (826
). The conversion for converting this measurement hole 9 deviation from camera coordinates to original coordinates is performed by converting the measurement hole deviation in camera coordinates to the camera magnification (read in step S6) stored as basic data for each measurement hole. It is an extremely simple method that only requires dividing by the camera magnification obtained from the unit length of the mark, and performing trigonometric function calculations based on the angle information of the measurement hole (the angle information input and stored in steps S12 and S13). be. Therefore, the conversion to the original coordinates does not take much time, and the measurement time can be shortened, and the computer constituting the control/processing means 6 can also be miniaturized.

Next, the control/processing means 6 determines whether the deviation of the measurement hole from the original coordinates is within an allowable error 52.
7) If the judgment is YES and is within the tolerance, the deviation of the measurement hole and the pass/fail judgment (in this case, the judgment is "good") are immediately memorized (S28), while if the judgment is NO and it is within the tolerance At that time, the lamp was lit and an alarm was issued (S 29
), then check the deviation of the measurement hole and pass/fail judgment (in this case, “fail”)
(determination) is stored (S28). Next, it is determined whether the number of measurements N is equal to the total number of measurement holes Nt (530), and if this determination is No, the number of measurements N is counted up by one (S31), and then the next measurement hole is Continue the measurement described above.

Then, when the number of measurements N becomes equal to the total number of measurement holes Nt (when the determination in step S30 is YES), the robot playback is ended (S32). In addition, control and
The processing means 6 summarizes the memorized measurement hole deviation and pass/fail judgment for each measurement hole (S33), prints it on the printer device 7, and displays it on the monitor display device 8 (S34, 535), and sets the standard. The measurement for body 2 ends (836). After the above robot playback and measurement of the measurement body 2 are completed, the measurement body 2 is carried out from the surface plate 1 (S37). after that,
Next, measurement of the measurement body 2 conveyed onto the surface plate 1 is performed in the same manner.

In the above embodiment, the present invention was applied to hole position measurement in an automobile body as a vehicle body part.
In addition to automobile bodies, the present invention can also be similarly applied to hole position measurement in vehicle body parts such as automobile doors. In addition to measuring hole positions, the present invention can also be applied to measuring and determining whether or not a reference position such as an edge position, a gap, or a step is at a predetermined position.

(Effects of the Invention) As described above, according to the method for measuring the reference position of a car body part according to the present invention, an original drawing is made around the reference position of the car body part to be measured using an articulated robot and a camera. Marks indicating the axial direction and unit length based on the coordinate axes,
Read on camera coordinates during robot teaching,
By comparing this basic data with the read data on the camera coordinates of the reference position of the vehicle body part to be measured, it is possible to quickly and accurately measure positional deviations of the reference position while facilitating robot teaching. The measurement range of positional deviation can be expanded. In addition, since calculations for displaying positional deviations in original coordinates are simple, measurement time can be further shortened, and equipment costs can be reduced by downsizing the combination unit. , which is very advantageous in implementation.

[Brief explanation of the drawing]

The drawings relate to embodiments of the present invention, and FIG. 1 is a flowchart showing a method for measuring measurement holes in an automobile body, and FIGS. 2 and 3 are side views of an apparatus used to carry out the measurement method. The figure and the plan view, FIG. 4, are schematic diagrams showing marks made in the measurement holes of the reference body and the angles that the reference holes make with the three axis directions of the drawing coordinates. 3...Articulated robot, 5...Camera.

Claims (1)

[Claims] (1) A reference position measurement method that measures the reference position of a car body part using an articulated robot and a camera installed at the tip of the robot, with respect to the reference position to be measured of a reference car body part. , placing marks around the reference position to indicate the axial direction and unit length based on the original drawing coordinate axes, reading the above marks on the camera coordinates during camera positioning by robot teaching, and storing them as basic data; A camera that is automatically positioned with respect to the part by a robot reads the reference position of the car body part on the camera coordinates, and compares this read reference position of the car body part with the above basic data to find the deviation in the camera coordinates. A method for measuring a reference position of a vehicle body part, comprising: calculating the deviation based on the axial direction and unit length of the mark to obtain a deviation in the original coordinates.