JPH0445314B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to an industrial robot system, and in particular, to a workpiece position shift detection system suitable for use in a sealing robot system, etc. that requires correction of the amount of shift of a workpiece. It is related to the device.

``Prior art'' Painting and welding robots used in automobile painting lines and welding lines require accurate detection of positional deviation of the car body as a workpiece and feedback to the robot control device. ing.

Conventionally, a device disclosed in US Pat. No. 4,639,878 is known as a device applied to this positional deviation detection.

This uses three cameras that can obtain two-dimensional image data to detect the positional deviation of the vehicle body in three-dimensional space (represented by six values). By modifying the motion of the robot, it is possible to always keep the motion of the robot relative to the vehicle body constant.

"Problem to be Solved by the Invention" However, as is well known, devices that use two-dimensional image data as described above require a large amount of processing time to process the data, resulting in slow response times. There was a problem that the speed of the line to which the device was applied could not be increased.

In addition, a high-performance arithmetic unit is required for data processing, and the camera itself is expensive, so there is a problem that the entire device becomes expensive.

Furthermore, the adjustment work for the above-mentioned cameras is generally much more complicated than for ordinary one-dimensional sensors.
As a result, the adjustment work for the entire device became time-consuming.

It is also possible to configure the device simply by using only one-dimensional sensors without using the above camera, but in this case, in the worst case, six sensors would be required, making the device expensive. I get used to it.

The present invention was made in view of the above-mentioned conventional problems, and uses only a small number of one-dimensional sensors.
Moreover, it is an object of the present invention to provide a workpiece positional deviation detection device that can detect positional deviation of a workpiece through simple data processing.

"Means for Solving the Problems" A workpiece position shift detection device of the present invention includes a one-dimensional image sensor arranged so that a part of light incident from the front is blocked by a detection part of the workpiece;
a light source that is disposed on the same side of the detection unit as the image sensor and irradiates the detection unit with a light beam from a direction tilted with respect to a center line of a light beam incident on the image sensor; The present invention is characterized by comprising a calculation device that calculates the amount of positional deviation of the detection unit from the position of the brightness/darkness switching unit appearing in the brightness/darkness pattern that is output.

"Function" With the above configuration, the amount of displacement of the position of the detection part of the workpiece in the detection width direction of the one-dimensional image sensor (width direction of the light beam incident on the sensor) By blocking the light that enters the one-dimensional image sensor from the back side, the amount of shift in the position of the bright/dark switching part (where it changes from dark to bright or from bright to dark) that appears in the bright-dark pattern output by the one-dimensional image sensor It will be proportional.

In addition, the amount of shift in the position of the detection part of the workpiece in the detection direction of the one-dimensional image sensor (direction of the center line of the light beam incident on the sensor) is such that the brightness of a part of the detection part increases due to the light irradiated from the light source. As a result, it is proportional to the amount of shift in the position of the bright/dark switching section appearing in the bright/dark pattern of the one-dimensional image sensor.

This is because the light source is configured to irradiate the detection section with a light beam from a direction oblique to the detection direction of the image sensor. This is because the position shifts in the direction of the detection width in proportion to the amount of positional shift of the detection section in the detection direction.

Therefore, in the arithmetic device, the position of each bright/dark switching part that appears in the bright/dark pattern output by the image sensor when the workpiece is at the reference position,
With a simple process of comparing with that at the time of detection,
The amount of positional deviation of the detection section of the workpiece in the two directions can be easily calculated.

In other words, the difference between the position of the light-dark switching part of the light-dark pattern when the workpiece is at the reference position and the position of the light-dark switching part of the light-dark pattern at the time of detection is multiplied by a predetermined proportional constant. Through this process, the amount of positional deviation of the detection section of the workpiece in the two directions is determined.

Therefore, with the above configuration, one one-dimensional image sensor can detect two amounts of positional deviation of the workpiece, and when the positional deviation of the workpiece occurs in all directions in three-dimensional space (in this case,
(6 values need to be detected), it is sufficient to set three detection sections for the workpiece and provide one one-dimensional image sensor for each. Moreover, even in this case, the processing of the data output from each image sensor is extremely simple as described above.

"Embodiment" Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

First, the configuration of the positional deviation detection device of this embodiment will be explained with reference to FIGS. 1 to 3. In these figures, numerals 1 to 3 indicate one-dimensional image sensors each consisting of a photodiode array. These image sensors 1 to 3 optically detect the position of a car body 4 as a workpiece, and are provided on one side of a line where the car body 4 is intermittently fed. The image sensors 1 to 3 each point their tips toward the detection section of the vehicle body 4, that is, the image sensor 1 faces the front pillar 4a of the vehicle body 4, and the image sensor 2
is installed in the front wheel house 4b of the vehicle body 4, and the image sensor 3 is installed in the rear wheel house 4c of the vehicle body 4.
is placed towards.

A light source 5 made of a high-frequency fluorescent lamp is installed in the left-right direction in FIG. 2 at a position facing the image sensor 1 across the line.
The image sensor 1 measures the position of the front pillar 4a in the line traveling direction (hereinafter referred to as the x-axis direction) by detecting the light emitted from the light source 5.

In addition, at a position facing the image sensor 2,
A light source 6 similar to the light source 5 is installed in the vertical direction, and a light source 7 similar to the light sources 5 and 6 is installed in the vertical direction at a position facing the image sensor 3. The image sensors 2 and 3 are
By detecting the lights emitted from the light sources 6 and 7, respectively, and detecting the lights B and B emitted from the light sources 8 and 9, which will be described in detail later, the lower ends of the front wheel houses 4b and 4c are detected in the vertical direction. (hereinafter referred to as the z-axis direction) and its position in the depth direction (vertical direction in FIG. 1, hereinafter referred to as the y-axis direction).

As shown in FIG. 3, light sources 8 and 9 are attached to the upper portions of the image sensors 2 and 3, respectively, with brackets 10 and 11 with their tips facing diagonally downward. These light sources 8,9
, slit beams B and B are irradiated to the position detection surfaces of the image sensors 2 and 3, that is, the front wheel house 4b and the rear wheel house 4c, respectively, and the irradiation angle is set according to the detection direction of the image sensors 2 and 3 ( They are arranged to form an angle φ with respect to the direction of the center line of the light flux incident on the image sensors 2 and 3, respectively. This angle φ is
The value is set to be sufficiently large compared to the angle θ of the field of view of the image sensors 2 and 3.

The image sensors 1 to 3 are connected to an arithmetic unit 15 via converters 12 to 14, respectively, and a storage device 16 is further connected to this arithmetic unit 15.

This positional deviation detection device consisting of the above configuration is
The image sensor 1 can detect the displacement of the vehicle body 4 in the x direction, and the image sensors 2 and 3 can each detect the displacement of the vehicle body 4 in the y and z directions, and the detection principle will be explained below. .

First, to explain the image sensor 1,
When the vehicle body 4 is transported along a line and placed at a predetermined position, a part of the light emitted from the light source 5 is blocked by the front pillar 4a, and therefore the image sensor 1 detects a specific bright and dark pattern. To detect. Then, the position of the pillar 4a is detected based on which element is OFF (dark) among the n elements constituting the image sensor 1, and from this, the position in the x-axis direction of the vehicle body is determined by the arithmetic unit 15. Recognized.

Here, if the position of the vehicle body 4 shifts and the position of the front pillar 4a shifts from the above position in the x direction, the light and dark pattern detected by the image sensor 1 changes in response to the shift. From the pattern, the position of the pillar 4a after being shifted can be detected. Therefore, by comparing the original position recognized by the calculation device 15 with the position after the deviation, the amount of positional deviation of the vehicle body 4 in the x-axis direction with respect to the original position can be detected.

Next, the principle of detecting positional deviation by the image sensors 2 and 3 will be explained with reference to FIGS. 4 and 5. Note that since the image sensors 2 and 3 operate in exactly the same way, only the image sensor 2 will be described.

When the vehicle body 4 is placed in a predetermined position, as shown in FIG. 4, a portion of the light from the light source 6 is blocked by the lower end of the front wheel house 4b, and as shown in FIG. , the slit light B from the light source 8 is directed to the front wheel house 4b.
is irradiated from the direction of angle φ. Therefore, the image sensor 2 has a bright and dark pattern as shown in FIG. Detects a pattern that turns ON (bright) at certain positions. From these ON (bright) positions (positions of bright/dark switching parts), that is, the values of Zi and Zj, the position of the slit light B on the surface of the front wheel house 4b and the z of the front wheel house 4b are determined.
The position in the axial direction is recognized by the calculation device 15.

Here, the position of the front wheel house 4b is changed from the above position as shown by the broken line in FIG.
Assuming a shift of ΔZ in the z-axis direction and ΔY in the y-axis direction,
The light and dark pattern detected by the image sensor 2 changes, and the ON (bright) position due to the slit light B changes from the original position Zi to ΔZi, and the ON position due to the light from the light source 6 changes.
The positions of (bright) are shifted by ΔZj from the original position Zj. The values of changes ΔZi and ΔZj on these patterns and the front wheel house 4b
The following relationship holds true between the positional deviation amounts ΔZ and ΔY under the condition that φ≫θ.

ΔZ=ΔZj ΔY=ΔZi/tanφ Therefore, by calculating the above equation using the calculation device 15 based on the detection signal of the image sensor 2, the position of the front wheel house 4b in the z-axis direction with respect to the original position can be determined. Both the amount of deviation ΔZ and the amount of positional deviation ΔY in the y-axis direction can be detected.

Similarly, from the detection signal of the image sensor 3,
Both the amount of displacement in the z-axis direction and the amount of displacement in the y-axis direction of the rear wheel house 4c can be detected, and furthermore, from the detection results of the image sensors 2 and 3, the displacement of the vehicle body 4 around the y-axis and the amount of displacement in the y-axis direction can be detected. Positional deviations around the axis can also be detected.

As explained above, in this device, image sensors 2 and 3 can each detect positional deviations in two directions, and only three image sensors 1 to 3 can detect positional deviations in five directions. The number of sensors required is smaller than that of conventional devices, so the device can be manufactured at low cost, and the effort required to adjust the sensors can be saved. In addition, since all sensors are optical image sensors,
Unlike when using an ultrasonic sensor, it is not affected by temperature or external noise, and detection accuracy can be improved.

As explained above, this device detects the positional deviation of the vehicle body 4 with respect to the reference position by always keeping the irradiation angle φ of the slit light B from the light sources 8 and 9 constant. Therefore, when installing or maintaining this device, it is necessary to accurately adjust the irradiation angle φ to a set value. The adjustment can be made as follows. First, a target plate 17 with an irradiation target position 17a displayed on its lower end as shown in FIG. 7 is prepared, and this target plate 17 is placed at a reference position. Then, visually or while checking the bright and dark patterns detected by the image sensors 2 and 3, adjust the irradiation angle φ so that the slit light B accurately irradiates the target position 17a as shown in FIG. In this state, the light sources 8 and 9 are fixed to the brackets 10 and 11. By doing so, the irradiation angle φ can be accurately and easily adjusted to the set value.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. For example, in the above embodiment, slit light is used as the light to irradiate the position detection surface, but the present invention is not limited to this, and spot light may also be used. Further, the type of light may be, for example, laser light using a laser oscillator as a light source, but is not limited thereto. Further, the light sources 8 and 9 may be installed at appropriate positions as long as they can emit light from a predetermined direction, and are not necessarily attached to the image sensors 2 and 3, but they may be attached to the bracket 1 as in the above embodiment.
By fixing the light sources 8 and 9 to the image sensors 2 and 3 using pins 0 and 11, it becomes easy to position the light sources 8 and 9 and adjust the irradiation angle φ.

In addition, in the above embodiment, a case was explained in which three image sensors were used to measure positional deviations in five directions: each of the x, y, and z axes, and rotations around the y and z axes. It goes without saying that if there is no need to detect rotational displacement, either one of the image sensors 2 and 3 may be omitted. Note that rotation around the x-axis can also be easily detected by adding one more image sensor.

"Effects of the Invention" According to the present invention, data processing for detecting the amount of positional deviation of a workpiece is extremely simple, and one one-dimensional image sensor is used for two amounts of positional deviation to be detected. Because it is enough,
The following effects are produced.

The response speed of the device is improved, and the speed of painting lines using robots can be much faster than before.

The device can be configured using only inexpensive one-dimensional image sensors in the same number as cameras in conventional devices, and the arithmetic unit does not have to be as high-performance as conventional devices, making the device extremely inexpensive. .

Since the device can be configured using only one-dimensional image sensors that are easy to adjust, in the same number as the cameras in the conventional device, the adjustment work for the entire device becomes extremely easy.

[Brief explanation of the drawing]

Figures 1 to 5 show one embodiment of the present invention, with Figure 1 being a plan view, Figure 2 being a side view, and Figure 3 being a side view.
The figure is a front view, and FIGS. 4 and 5 are diagrams for explaining the principle of detecting positional deviation by a one-dimensional image sensor, respectively. Figures 6 and 7 are diagrams for explaining the method of adjusting the sensor in the device of this embodiment, with Figure 6 showing the state in which the adjustment is being made, and Figure 7 showing the target used for adjustment. It is a figure showing a board. 1, 2, 3...1-dimensional image sensor, 4...
Vehicle body (work), 4a...Front pillar (position detection surface), 4b...Front wheel house (position detection surface), 4c...Rear wheel house (position detection surface), 8, 9...Light source, 15... computing device,
B...Slit light (light), φ...irradiation angle.

Claims (1)

[Claims] 1. A one-dimensional image sensor arranged so that a part of light incident from the front is blocked by a detection part of the workpiece, and a one-dimensional image sensor arranged on the same side as the image sensor with respect to the detection part and connected to the image sensor. A light source that irradiates the detection section with a light beam from a direction inclined with respect to the center line of the incident light beam, and a positional deviation of the detection section from the position of the brightness/dark switching section that appears in the brightness/darkness pattern output by the image sensor. A workpiece position shift detection device comprising: a calculation device that calculates a quantity.