JPS63156560A - Device for detecting aberration of work - Google Patents

Abstract

PURPOSE:To easily and accurately carry out adjustment for obtaining the correlation between the absolute magnitude of the aberration of a work and the signal of a one-dimensional position sensor, by providing plural one-dimensional position sensors to one movable sensor mount. CONSTITUTION:The measuring directions of the plural one-dimensional position sensors 1-3, 8, and 9 for detecting the position of a work 4 are directed in the directions different from each other, and one sensor mount 20 movable along each measuring direction is provided. The sensor mount 20 is moved in the three-dimensional directions X, Y, and Z, and correlational data can be obtained from the absolute magnitude of the moving quantity 7 and the detection values from the sensors 1-3, 8, and 9. By this method, large-scale equipment in the case where the work 4 is moved can be dispensed with, the errors in the relative positions of the sensors 1-3, and 9 when the device is installed and the errors in the moving quantities of the respective sensors 1-3, 8, and 9 can be reduced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an industrial robot system, and is particularly applicable to a no-ring robot system that needs to correct the deviation of the jaws of a car body as a workpiece. This paper relates to a suitable workpiece position shift detection device.

``Prior Art'' Painting robots used on automobile rolling lines require accurate detection of positional deviations of the car body as a workpiece and feedback to the robot's control device.

Conventionally, the following systems have been proposed as devices applied to detecting this positional deviation.

In other words, four television cameras were installed below the painting line, and these television cameras were used to detect four holes on the underside of the car body (holes specially provided as base holes, or specially formed holes for mounting parts). The images of the reference holes are analyzed to determine the position of the center of the hole, major axis, minor axis, and inclination. 11 (an elliptical image is obtained from the tin hole), and from the obtained data, calculate the amount of three-dimensional deviation of the car body, the deviation in each of the x, y, and z directions, and the Rotation (rolling, pitching, yawing) around the axis and the Z axis are calculated.

``Problems to be Solved by the Invention'' However, positional deviation detection using the two-legged conventional technology has the following problems.

(a) In order to perform image processing, it is necessary for the control computer to process a large amount of data, so data processing takes time and the robot's responsiveness deteriorates, which limits the ability to speed up the line. Become.

(b) When using a television camera, the resolution is limited to about 1% of the entire field of view, so sufficient positioning accuracy cannot be obtained.

In order to solve the above problems, the applicant filed a patent application in 1986-143.
In No. 860, we proposed a "device for detecting workpiece position deviation." In this apparatus, a plurality of one-dimensional position sensors are arranged with their measurement directions facing different directions, and the positional shift of the workpiece is detected based on data obtained from these sensors.

Incidentally, in the positional deviation detection device using the above one-dimensional position sensor, adjustment work is required to determine the correlation between the absolute amount of positional deviation of the workpiece and the output signal of the position sensor. To perform this adjustment, multiple one-dimensional position sensors are moved relative to the workpiece in its measurement direction (for example, x in a Cartesian coordinate system).
.

Therefore, as methods for performing such adjustment, a method of moving the workpiece and a method of providing a plurality of position sensors on a plurality of tables movable along the measurement direction have been proposed.

Among these methods, the method for moving the workpiece is to provide a workpiece movement mechanism that can move the workpiece by an arbitrary distance in the X, Y, and Z axis directions separately from the line in which the robot is to be used. Party B used a moving mechanism to perform the above-mentioned adjustment work, but the following problems arose.

(a) When the workpiece is a large object such as an automobile, large-scale equipment is required as the workpiece moving mechanism described above.

(b) The actual installation location is the stomach, so adjustments are made at the stomach, so when moved to the actual measurement location and put into operation 1:.

Easy to cause errors.

In addition, a method for installing multiple position sensors on a movable table is to provide as many x, y, and z tables that are movable along the measurement direction as the number of position sensors, and to install each position sensor individually on these tables. The above-mentioned adjustment work was carried out by moving the parts individually, but even with this method, there were the following problems.

(a) It is difficult to match the coordinates of the xyz table where each position sensor is installed.

(b) Since the parts are moved individually, it is easy to make mistakes in direction, amount of movement, etc. during adjustment work.

(c) Many adjustments are required.

The present invention has been proposed in view of the above circumstances, and therefore provides a workpiece positional deviation detection device that can easily and accurately perform adjustment work for determining the correlation between the absolute amount of positional deviation of a workpiece and the signal of a one-dimensional position sensor. The purpose is to obtain.

"Means for Solving the Problem" In order to achieve the above object, the present invention provides a plurality of one-dimensional position sensors for detecting the position of a workpiece, each of which is positioned at a workpiece measurement position with their measurement directions facing different directions. established,
In the workpiece positional deviation detection device that measures the positional deviation of the workpiece based on the outputs of the plurality of sensors, the plurality of one-dimensional position sensors are provided on one sensor mounting base that is movable along each measurement direction. This is how it was done.

"Function" By moving one sensor mounting base on which the plurality of one-dimensional position sensors are mounted in each of the x, y, and z directions, the sensor and the workpiece can be moved relative to each other. Correlation data can be obtained from the absolute value of the movement amount and the detected value of the sensor.

[Example j Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

1 to 6 show one embodiment of the present invention. Reference numerals 1 to 3 denote one-dimensional image sensors (one-dimensional position sensors) consisting of CCDs, and these image sensors l to 3 are attached to one side of a line that is intermittently fed to a vehicle body (work) 4. It is set in. A light source 5 made of a high-frequency fluorescent lamp is provided at a position facing the image sensor 1 across the line, and by detecting the light rays emitted from the light source 5, the line of the front pillar 4a of the vehicle body 4 is The position in the traveling direction (hereinafter referred to as the X-axis direction) is measured. Further, a light source 6 configured similarly to the light source 5 is provided at a position facing the image sensor 2, and by detecting the light rays emitted from the light source 6, the front wheel house 4
The position of the lower end of b in the vertical direction (hereinafter referred to as the Z-axis direction) is measured. Further, a light source 7 configured similarly to the light sources 5 and 6 described in ml is provided at a position facing the image sensor 3, and by detecting the light rays emitted from the light source 7, the rear of the vehicle body 4 is The position of the lower end of the wheel house 4C in the vertical direction is measured.

Further, reference numerals 8 and 9 are ultrasonic distance sensors as one-dimensional position sensors, and these distance sensors 8 and 9 are ultrasonic distance sensors as one-dimensional position sensors.
9 measures the distance to the vehicle body at two locations separated in the longitudinal direction of the vehicle body 4, and measures the distance to the vehicle body 4 in the left and right direction (hereinafter referred to as the y direction).
The position is now measured.

Furthermore, a reference ultrasonic sensor IO for correction is provided at the rear position of the ultrasonic sensors 8 and 9, and this reference ultrasonic sensor IO is made to constantly measure a known distance I7 to the reference reflector 11. By setting the ultrasonic sensors 8 and 9, a correction signal is obtained to correct measurement errors of the ultrasonic sensors 8 and 9 due to changes in temperature or atmospheric pressure.

And the image sensor [~3 is conversion'? :, 12
14 and the ultrasonic distance sensors 8 to 10 are respectively connected to an ei calculation device 18 via transducers 15 to 17, and a storage device 19 is connected to this calculation device 18.

Next, the configuration of the sensor mounting base 20, which is movable in the X, Y, and Z axis directions, on which each one-dimensional sensor is mounted will be described. The image sensor l is attached to a sensor mounting base 21. Similarly, the image sensor 2 is mounted on the sensor mount 22, the image sensor 3 is mounted on the sensor mount 23, the ultrasonic distance sensor 8 is mounted on the sensor mount 24, and the ultrasonic distance sensor 9 is mounted on the sensor mount 25 in the measurement direction. It is set towards. Above sensor mounting base 21.22, 23, 24.25
are attached to specific locations on the member 26 that is movable in the Z-axis direction along the inside of the framework 27. Framework 2
A motor 28 is attached to 7, and by controlling this motor 28, the member 26 can be kept stationary in the Z-axis direction.

The framework 27 is supported so as to be movable in the x1111 direction along a member 29, and can be kept stationary by controlling a motor 30 attached to the member 29. Further, the member 29 is supported so as to be movable in the X-axis direction along the member 31, and can be freely moved by controlling a motor 32 attached to the member 31.

The motors 28, 30, 32 are connected to the d calculation device 18 via servo amplifiers 33, 34, 35, respectively.

Next, perform a detection operation in the detection device.

First, the measurement principle of the 61-dimensional image sensors 1 to 3 will be explained using the one-dimensional image sensor 1 as an example.

That is, when the vehicle body 4 is transported along a line and placed at a predetermined position, the light rays emitted from the light source 5 are blocked by the front pillar 43, so that a specific bright and dark pattern is detected by the image sensor 1. Then, the position of the pillar 4a is detected by which element among the 4 elements that make up the image sensor 1 is OFF (dark) and Δ^, and from this, the position of the pillar 4a is detected in the X-axis direction of the vehicle body. The location of is recognized by the computing device, %7.18. In addition, the image sensors 2 and 3 detect the rotational position 1 of the vehicle body 4 in the Z-axis direction (device) based on the same principle, and from the measured values of the image sensors 2 and 3,
1 is detected.

On the other hand, the ultrasonic transducers 15 and 16 are connected to the ultrasonic distance sensor 8.
・The time T,,T, required for the ultrasonic waves emitted from 9 to be reflected by the car body 4 and received is measured, and by processing this time data as shown below, the time from each sensor to the car body is measured. The distance M L I and M L I in the y-axis direction are determined. Also, these L1. L
From t, the rotational position of the vehicle body around the Z axis can be determined.

L,=(T,-Td)XL/(TRer-Td)L,=
(T, -Td) Distance to the reference reflector 11 TRef: Time required for the ultrasonic waves emitted from the reference ultrasonic distance sensor IO to be reflected by the reference reflector 11 and received Td: Electric circuit delay time (34 μs) Next, each The method of converting the position information obtained from the one-dimensional distance sensor 1, 2.3.8.9 into the absolute value of positional deviation will be explained below.

First, the vehicle body 4 is fixed at a predetermined position on the line.

Next, the arithmetic device 18 outputs an X-direction movement control signal for the sensor mount 20 to the servo amplifier 34, the servo amplifier 34 controls the motor 30, and the frame 27 of the sensor mount 20 is moved in the X-axis direction by the arithmetic device. 18 by a distance ΔX.

Then, the distance information obtained from each one-dimensional position sensor, for example, the distance information (1) of the image sensor l changes by Δ11. Similarly, the distance information I of the image sensor 2 is Δ
I2, the distance information I of the image sensor 3 changes by ΔI:l, the distance information L1 of the ultrasonic distance sensor 8 changes by ΔL1, and the distance information I of the ultrasonic distance sensor 9 changes by ΔL.

Next, in the same way, y of the sensor mounting base 20 is attached to the servo amplifier 35.
An axial movement control signal is output, and the motor 32 is controlled to cause the member 29 of the sensor mount 20 to move by a predetermined distance Δy in the y-axis direction. Then, distance information obtained from each one-dimensional position sensor 11+I! , [3,L 2. L
t are respectively Δll, ΔI, , Δ13°ΔL8. ΔL
It changes by t.

Furthermore, a control signal for moving the sensor mount 20 in the Z-axis direction is similarly output to the servo amplifier 33, and the motor 28 is controlled to move the member 26 of the sensor mount 20 by a set distance Δ2 in the two-axis direction. Then, the distance information of each one-dimensional distance sensor 1. , [2, [3, L, ,L, are respectively ΔI
l, Δ[7. Δ■3. It changes by ΔL1゜ΔL.

Through the above operations, correlation data between the sensor output and the absolute value of change as shown below can be obtained.

(ΔI, /ΔX, Δ1./Δy, Δ1./ΔZ) (Δr
t/ΔX, Δ+1/Δy, ΔI, /ΔZ) (Δ[3/Δ
X, ΔI3/Δy, Δ1. +/ΔZ)(ΔL,/ΔX,
ΔL, /Δy, ΔL, /ΔZ) (ΔL2/ΔX, ΔL,
/Δy, ΔL2/Δ2) 15 obtained in this way
These 15 pieces of correlation data are determined by the car model, so for each car model, these 15 pieces of data and the output of each sensor at the base position I lO + I 2Q + I 3Q + L
IQ+L 20 is stored in the storage device 19.

When actual positional deviation is detected, the above information is read from the storage device 19, and based on the read correlation data, the calculation device 18 calculates the absolute value of the displacement from the measurement data of each sensor. X.

Be able to know the displacement in each of the y and z directions, as well as the rotational displacement around the y and Z axes. Then, it would be possible to supply a correction signal to the robot according to the positional deviation information obtained in this way.

As described above, in this embodiment, a plurality of one-dimensional image sensors, 2, 3
and the ultrasonic distance sensors 8 and 9 are provided on one sensor mount 20 that is movable along each measurement direction;
This sensor mount 20 is provided with motors 28, 30, 32, and the arithmetic unit 18 controls the motor to move the sensor mount 20. This has the following effects: (1) The workpiece can be moved easily. 1. It does not require large-scale equipment as in the case of hyperactivity.

(ii:)? Since Ji number of sensors are mounted on one sensor mount, errors in the relative positions of the sensors are less likely to occur when the device is installed, and errors are also less likely to occur in the amount of movement of each sensor when measuring correlation data.

(...) Data can be easily corrected in response to changes in the senna over time and changes in the workpiece.

(1v) Sensor installation requires no work at the location, and correlated data can be obtained safely and easily.

(v) It is possible to control the sensor by moving it away from the workpiece when transporting the workpiece, and moving it closer to the workpiece during measurement, making it possible to perform highly accurate measurements and prevent interference between the sensor and the workpiece when transporting the workpiece. .

In addition, in the above embodiment, the motors 28, 30, 32
Although the sensor mounting base 20 was moved by controlling the effect can be obtained.

In addition, in the above embodiment, five senna 1.2° 3.8
．． 9 was used to measure the positional deviation in the X, y, Z directions, yM rotation, and the Z axis.
Or use 6 sensors in X, Y, Z direction and
The present invention can be applied to cases where positional deviations in six directions around an axis, around the y-axis, and around the Z-axis are to be measured.

"Effects of the Invention" As is clear from the above explanation, the present invention has a plurality of one-dimensional position sensors that detect a single positional deviation of a workpiece, each of which is movable along a fixed direction. Since it is mounted on the stand, the following effects are achieved.

(1) It does not require large-scale equipment unlike the case where the workpiece is moved.

(ii) Since multiple sensors are mounted on one sensor mount, errors in the relative position of each sensor are less likely to occur when the device is installed, and fewer errors occur in the amount of movement of each sensor when measuring correlation data. .

(Mountain) Data can be easily corrected in response to changes in the sensor over time and changes in the workpiece.

[Brief explanation of the drawing]

1 to 6 show an embodiment of the present invention,
Figure 1 is a plan view including the computing device, etc., Figure 2 is a plan view not including the computing unit, etc., Figure 3 is a side view, Figure 4 is a front view, and Figure 5 is a side view of the sensor mounting base. , FIG. 6 is a front view of the sensor mount. 1 to 3...What order ratio image sensor (one-dimensional position sensor), 4...Car body (work), 8.9...
...Ultrasonic distance sensor (one-dimensional position sensor).

Claims (1)

[Claims] A plurality of one-dimensional position sensors for detecting the position of the workpiece are oriented in different directions, and are mounted on a single sensor mount that is movable along each measurement direction.
A workpiece positional deviation detection device, characterized in that the positional deviation of the workpiece is measured based on outputs of the plurality of sensors.