JPH07332927A - Work-position detector - Google Patents

Abstract

PURPOSE:To perform the highly accurate detection at a high speed by operating the position of a characteristic point based on the detected distance data, which are obtained when a detector is moved in accordance with the instruction data instructed with the detector, and the instruction data. CONSTITUTION:For a laser displacement sensor 3, the scanning conditions of a robot tip 2b are instructed so that the scanning is performed so as to cross a welding line in the inclined lower direction A at a specified angle (a) with respect to a horizontal line. The time difference between the scanning start time (ts) and the characteristic- point detecting time (tf) is the virtual scanning time until the detection of the characteristic point, during which the scanning is performed at the instructed speed without acceleration time. The scanning time is multiplied by the scanning speed, and a scanning distance L is obtained. A horizontal scanning distance DELTAS and a vertical scanning distance DELTAZ of a sensor position R are obtained on the basis of the distance L and the angle (a). The sensor position R(Xf, Yf, Zf) at the time of detection of the characteristic point is obtained on the basis of the distances DELTAS and DELTAZ and the sensor position R (Xs, Ys, Zs) at the scanning start time. The coordinate position (X, Y, Z) of the characteristic point 11a is obtained on the basis of the sensor position R (Xf, Yf, Zf) and a sensor displacement Zf.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting the position of a work, and more particularly to a device for detecting the position of a processing work point such as a welding line to be processed prior to a processing work performed by a robot.

[0002]

2. Description of the Related Art In an arc welding robot, welding work is performed by moving the tip of a welding torch attached to the tip of an arm along a welding line.

In this case, in order to cope with installation errors and variations of the work, a sensor for detecting the above welding line is attached to the tip of the robot arm, and this is positioned on the welding line before the welding work to sense the welding line, A method is available in which detection data on the position and shape of the welding line is acquired, and errors in the data on the torch position and trajectory obtained by teaching are corrected based on the detection data, and then welding is performed. A laser sensor using a laser beam as a detection medium may be used as the welding line detection sensor, and the laser sensor is roughly classified into two.

One is a two-dimensional laser sensor. For example, Japanese Patent Application Laid-Open No. 1-245103 discloses a technique for measuring the position of a work by using a two-dimensional laser sensor. The two-dimensional laser sensor scans the projected laser light with a scanning mirror inside the laser sensor, and it is possible to detect the distance from the irradiation position of the laser light to the sensor and the two-dimensional position of the irradiation position of the projected laser light in the scanning direction. Is.
Therefore, if this two-dimensional laser sensor is attached to the robot and position detection is performed while the robot is stationary on the work, the two-dimensional detection position output from the sensor and the coordinate position of the sensor in the coordinate system of the robot are used. It is possible to measure the three-dimensional position of the work in the robot coordinate system.

The other laser sensor is a one-dimensional laser sensor which can detect only the distance between the sensor and the work surface irradiated with the laser beam. The three-dimensional position of the work is measured by mounting the one-dimensional laser sensor on the robot and moving the robot to scan the work. That is, the one-dimensional laser sensor is attached to the robot, and the sensor is scanned by moving the robot arm. Then, during scanning, sensing is performed by a sensor to acquire scan data on the surface of the work, and the robot is stopped when a feature point on the work is detected. Then, the three-dimensional position of the feature point on the work is measured by the coordinate position of the sensor in the robot coordinate system and the displacement which is the output of the sensor when the feature point is detected.

[0006]

However, in the position measurement using the two-dimensional laser sensor, although the measurement can be performed at high speed and with high accuracy, the scanning distance of the projected laser light is several tens of millimeters, so that the detection range is detected. However, it may not be possible to deal with a large work position deviation or an indefinite work shape. Further, since a mechanism for scanning the laser projection light such as a scanning mirror is required, the structure of the sensor becomes complicated and the cost of the sensor body is high.

In the position measurement using the one-dimensional laser sensor, the sensor main body is cheaper than the two-dimensional laser sensor, and the robot is moved and scanned, so that a wide range of detection is possible. When accuracy is required, on the other hand, the scanning speed must be low and high speed cannot be achieved.

That is, in this position measurement, since the movement of the robot is stopped at the time of detecting the characteristic point, the three-dimensional position of the characteristic point of the work is output based on the detected position output from the sensor. In the meantime, there is a time lag that is the sum of the time required to process the detected data and recognize the feature point, and the time required to stop the robot after detecting the feature point. The higher the scanning speed, the larger the detection error of the scanning position of the sensor obtained by multiplying the time lag by the scanning speed of the robot.

As described above, the position measurement using the one-dimensional laser sensor is inexpensive and can measure a wide range, but it is difficult to achieve both high speed and high accuracy.

The present invention has been made in view of these circumstances, and it is possible to detect the position of a work at high speed and with high accuracy even when a one-dimensional laser sensor is used. The purpose is.

[0011]

Therefore, in the main invention of the present invention, a detection device for detecting the distance to the surface of the work is located on a feature point of the work, and the detection device and the feature are used by the detection device. In a position detecting device for a work, which detects a distance to a point and detects the position of the characteristic point based on the detected distance and the position of the detecting device,
The detection data of the detection device acquired when the detection device teaches the movement of the detection device so as to move across the feature point, and the detection device is moved according to the teaching data, and the teaching data. The position of the characteristic point is calculated based on

[0012]

According to the structure of the present invention, as shown in FIGS. 3 and 4, the detecting device 3 is moved in the predetermined direction A so as to cross the feature point 11a in accordance with the teaching data, and the detecting device at this time is moved. The data of the detection distance Z of 3 is acquired. Then, the position (X, Y, Z) of the characteristic point 11a is calculated based on the acquired distance data Z and the teaching data.

As described above, the detection device 3 is scanned by teaching without stopping the detection device 3 on the feature point 11a, all distance data of the detection device 3 is acquired, and then the feature point 11a is acquired based on the acquired data. Since the position of is calculated, the position of the feature point 11a can be obtained at high speed and with high accuracy regardless of the scanning speed.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a work position detecting device according to the present invention will be described below with reference to the drawings. In addition, in this embodiment, a welding robot that performs arc welding work on a predetermined processing work point is assumed, but the invention is not limited to this, as long as it is a robot that performs processing work on a predetermined processing work point, It can be applied to other robots such as a robot for sealing work.

FIG. 1 is a block diagram showing the configuration of the robot system of the embodiment.

As shown in FIG. 1, the welding robot 1 is
It is an articulated robot, and a welding torch 2 is arranged at the tip of its tip arm 1a. This welding torch 2
Has a shaft 2a at its tip, and its tip 2b is moved along a welding line 11 of a workpiece (hereinafter referred to as a workpiece) 10 to perform welding work.

The position of the welding line 11 is detected by the laser displacement sensor 3 in advance before the welding operation.

As shown in FIG. 8, the laser displacement sensor 3 is mounted on the torch shaft 2a via, for example, a bracket 12, and the laser beam J is applied to the workpiece machining surface 10.
The one-dimensional detection of the reflection position when irradiating on a is performed, whereby the mounting position (hereinafter referred to as "sensor position") R of the displacement sensor 3 to the torch shaft 2a and the irradiation position PL.
The distance (displacement) Z from

The detection signal Z of the displacement sensor 3 is applied to the sensor amplifier 4 and input to the sensor controller 6 via the A / D converter 5. The sensor controller 6 is C
It has a PU 7 and a memory 8, and as will be described later, a predetermined arithmetic processing is performed on the basis of the input detection signal Z, and finally the three-dimensional shape of each point 11a on the welding line 11 of the work 10 is obtained. The coordinate position (X, Y, Z) is output as the coordinate position in the robot coordinate system XYZ (see FIG. 3).
reference).

The robot controller 9 has a CPU 13 and a memory 14, and performs processing for correcting the teaching data of the welding line 11 based on the position data of the welding line 11 input from the sensor controller 6 by these. A drive control signal S for the robot 1 is generated and output based on the corrected teaching data,
Drives and controls each axis of the robot.

First Embodiment (FIG. 2) FIG. 2 is a flowchart showing the processing procedure of the work position detection processing performed by the controllers 6 and 9. Hereinafter, the processing content will be described with reference to FIGS.

First, as shown in FIG. 3, the robot 1 scans the laser displacement sensor 3 obliquely downward A at a predetermined angle a with respect to the horizontal line on the condition that the laser displacement sensor 3 crosses the welding line 11. The robot controller 9 is taught the scanning conditions such as the scanning start position, the scanning end position, and the scanning angle a of the tip 2b. Sensor 3
The movement of the sensor 3 is instructed so that the detection output Z changes at the start of scanning and thereafter the detection output Z changes.
The point is that the sensor 3 moves in the direction in which the detection output Z of the sensor 3 changes.
The instruction may be made to move (step 101).

When this teaching is given, the sensor controller 6 outputs a command to the sensor 3 to perform sensing, and the sensor 3 starts sensing according to this command. As a result, the sensor amplifier 4 outputs an analog signal obtained by amplifying the output signal of the sensor 3, and the signal is converted into a digital signal by the A / D converter 5 at a constant sampling period, and the digital data Z
Are sequentially stored in the memory 8 of the sensor controller 6 in time series (step 102).

On the other hand, the robot 1 executes (plays back) the operation taught in the above step 101 in response to the drive command from the robot controller 9, and the point 11a on the welding line 11 and the sensor 3 are connected as shown in FIG. The sensor 3 is moved obliquely downward at a predetermined angle a from the scanning start position so as to intersect. It should be noted that the point 11a is a step portion, and is a characteristic point at which the output of the sensor 3 suddenly changes.

As a result, the output (displacement) of the sensor 3 corresponding to each time during scanning is stored as data in the memory 8 as shown in FIG. 4 (step 103). When the scanning is completed according to the teaching contents, the sensor controller 6 sends a command for ending the sensing to the sensor 3 and ends the sensing (step 104).

The CPU 7 then follows the memory 8 of the sensor controller 6 according to an algorithm created in advance.
Calculation processing is performed on the displacement data Z stored in.

That is, noise removal processing is performed on the displacement data Z to obtain the correspondence relationship between the time t and the sensor output Z as shown in FIG. Then, the graph of FIG. 4 is differentiated, and the differentiated line segment DV is subjected to threshold processing or the like to obtain the displacement Zs of the sensor 3 before the start of scanning,
The sensor 3 at the time ta at which the teaching speed is reached after passing the acceleration portion AC (curved portion in FIG. 4) at the time of starting scanning, the time tf at which the characteristic point 11a is detected, and the detection time tf at which the characteristic point 11a is detected.
The displacement Zf of can be extracted. In particular, the feature point detection time tf is the time at which the output of the sensor 3 suddenly changes at the feature point 11a, and therefore can be easily extracted.

The time at which the sensor 3 starts moving downward at the predetermined angle a, that is, the scanning start time ts is the time at which the displacement Z of the sensor 3 starts changing. You can ask for it.

That is, the characteristic point detection time tf from the time ta
Up to the portion where the displacement data changes linearly is a movement section where the teaching speed is constant. Therefore, the robot 1 accelerates the time component ts of the intersection point of the straight line L1 approximating the moving section and the straight line L2 indicating the initial displacement Zs of the sensor 3 to the teaching speed in a stepwise manner without the acceleration time. In this case, the virtual scanning start time ts is determined.

By determining such virtual scanning start time ts, the robot scanning system and the sensor measurement system can be synchronized (step 105).

The time difference tL between the scanning start time ts and the characteristic point detection time tf thus obtained is the virtual scanning time tL until the characteristic point 11a is detected by scanning at the teaching speed without acceleration time. , The scanning speed v0 at this scanning time tL
The scanning distance L from the start of scanning to the detection of the characteristic point 11a can be obtained by multiplying by.

Then, the horizontal scanning distance ΔS and the vertical scanning distance ΔZ of the sensor position R can be obtained based on the scanning distance L and the scanning angle a, and the horizontal scanning distance ΔS and the vertical scanning distance ΔZ of these sensor positions R can be obtained. And the feature point 11a from the sensor position R (Xs, Ys, Zs) at the start of scanning.
The sensor position R (Xf, Yf, Zf) at the time of detection can be obtained (step 106).

When the sensor position R (Xf, Yf, Zf) at the time of feature point detection is obtained in this way, the sensor position R (Xf, Yf, Zf) and the sensor displacement Zf at the feature point detection time tf already obtained are obtained. Based on the feature points 11a
The coordinate position (X, Y, Z) can be obtained (step 107).

In the first embodiment, the scan start time ts is obtained, but the scan end time te (see FIG. 4) also changes the output of the sensor 3 similarly to the scan start time ts. The scanning end time te is obtained, and the same processing as described above may be performed on the time difference tL between the scanning end time te and the characteristic point detection time tf. .

Further, in the embodiment, the scanning start point is set to the sensor 3
However, if an intermediate position is taught as a point where the detection output of the sensor 3 changes between the scanning start point and the scanning end point, the intermediate position is passed. It is also possible to obtain a time point to be set, perform processing similar to the scan start time ts for this time point, and calculate the position of the feature point 11a.

Second Embodiment (FIG. 5) In the first embodiment, the sensor position at the time of feature point detection is calculated by obtaining the time from the start of scanning to the feature point detection. Then, the sensor position at the time of feature point detection is calculated by obtaining the amount of change in the detection output of the sensor from the start of scanning to the feature point detection.

In the first embodiment, it is necessary to sense on a plane for a certain section from the start of scanning, but in this embodiment, there is no limitation to the detection path from the start of scanning or the end of scanning to the detection of feature points. Further, the position of the feature point of the work can be detected without depending on the scanning speed.

However, in this embodiment, in order to correct the movement distance of the sensor 3 in the detection direction (Z), the sensor 3 is taught in two different movement directions.

First, in step 201, the laser displacement sensor 3 by the robot 1 has a predetermined angle with respect to the horizontal line, that is, the vertical scanning distance, on the condition that the laser displacement sensor 3 crosses the welding line 11 as shown in FIG. 6A. A scan start position and a scan end position of the tip 1b of the robot 1 are scanned obliquely downward D1 at an angle such that the ratio of ΔZ and horizontal scanning distance ΔS (hereinafter, referred to as scanning distance ratio) is 1: R1. The robot controller 9 is taught the first scanning conditions such as the scanning amount ratio. Further, as shown in FIG. 8A, the robot 1 causes the laser displacement sensor 3 to have a scanning distance ratio 1: R2 different from the above scanning distance ratio 1: R1 on the condition that the laser displacement sensor 3 crosses the welding line 11. The robot controller 9 is instructed of the second scanning conditions such as the scanning start position, the scanning end position, and the scanning amount ratio of the tip end 2b of the robot 1 so that the robot is scanned obliquely downward D2 at such an angle.

In this way, the teaching is performed so that the sensor 3 is moved in the direction (vertical direction) in which the detection output Z of the sensor 3 changes.

When such teaching is given, the above step 1
Similarly to Nos. 02 to 104, the sensor 3 is scanned diagonally downward D1 as shown in FIG. 6A under the first scanning condition, and the displacement data Z shown as DL1 in FIG. 6B is time-series. (Steps 202, 203, 20)
4).

Similarly, under the second scanning condition, the sensor 3 is scanned obliquely downward D2 as shown in FIG.
The displacement data Z shown as DL2 in FIG. 6B is acquired in time series (steps 205, 206, 207). Then, the sensor controller 6 obtains the displacement Zs before scanning and the displacement Zf1 at the feature point detection time under the first scanning condition based on the time-series displacement data Z indicated as DL1. Then, the displacement difference of these displacements, ΔZ1 = Zs−Zf1 (1), is calculated (step 208).

Similarly, the displacement Zs before the start of scanning and the displacement Zf2 at the feature point detection time under the second scanning condition are set.
Is calculated and the displacement difference ΔZ2 = Zs−Zf2 (2) is calculated in the same manner as in the above equation (1) (step 20).
9).

Here, the detection direction of the sensor 3 (FIG. 6A)
When the displacement amount of the work surface from the start of scanning in the Z direction) to the detection of the feature point is ΔZw, the horizontal scanning distance ΔS,
That is, the scanning distance ΔS in the direction perpendicular to the sensor detection direction (X direction in FIG. 6A) is expressed by the following equations (3) and (4).

ΔS = R1 (ΔZ1−ΔZw) (3) ΔS = R2 (ΔZ2−ΔZw) (4) Therefore, the following relationships are obtained from these equations (3) and (4).

ΔS = R1 · R2 (ΔZ1−ΔZ2) / (R2-R1) (5) ΔZw = (R1 · ΔZ1−R2 · ΔZ2) / (R2−R1) (6) On the other hand, the first scan The vertical scanning distance under the conditions, that is, the scanning distance ΔZ in the sensor detection direction, has a relationship of ΔZ = ΔZ1−ΔZw (7). Therefore, the known scanning distance ratios R1 and R2 and the above equations (1) and (2) are used. Displacement difference ΔZ1, Δ obtained in
By substituting Z2 into the above equations (5) and (6), the horizontal scanning distance ΔS, that is, the scanning distance ΔS in the direction perpendicular to the sensor detection direction, and the workpiece surface displacement ΔZw can be obtained. Then, by substituting the workpiece surface displacement amount ΔZw and the displacement difference ΔZ1 obtained by the above equation (1) into the above equation (7), the vertical scanning distance ΔZ under the first scanning condition, that is, the scanning in the sensor detection direction. The distance ΔZ is obtained (step 210).

Then, the horizontal scanning distance ΔS and the vertical scanning distance ΔZ of the obtained sensor position R and the sensor position R (Xs, Ys, Zs) at the start of scanning under the first scanning condition are used under the first scanning condition. The sensor position R (Xr1, Yr1, Zr1) at the time of detecting the characteristic point 11a can be obtained (step 211).

Thus, when the sensor position R (Xr1, Yr1, Zr1) at the time of detecting the characteristic point under the first scanning condition is obtained, this sensor position R (Xr1, Yr1, Zr1) and the already obtained first position are obtained. The coordinate position (X, Y, Z) of the feature point 11a can be obtained based on the sensor displacement Zf1 at the feature point detection time under the scanning condition (step 21).
2).

Incidentally, the above steps 210 to 2
In 12, the position of the characteristic point is obtained based on the data under the first scanning condition, but the position of the characteristic point may be obtained based on the data under the second scanning condition.

In the second embodiment, the displacement Zs at the scanning start time is obtained. However, the displacement at the scanning end time or the intermediate position passing time is obtained, and this displacement and the displacement at the feature point detection time are obtained. Zf1 and Zf2
You may make it perform the same process based on the displacement difference with.

Third Embodiment (FIG. 7) Next, the position P (Xr, Yr, Z) of the tip 2b of the robot 1 will be described.
By storing r), the position (X,
An example of measuring Y, Z) will be described with reference to the flowchart in FIG. 7.

The CPU 13 of the robot controller 9 calculates the position P (Xr, Yr, Zr) of the tool tip 2b based on the data indicating the driving position of each axis of the robot 1, and the tip position data P is stored in the memory 14. Remembered.
The tip position data stored in the memory 14 can be accessed by the sensor controller 4.
Then, similar to step 101, the robot controller 9 is taught a predetermined scanning condition so that the sensor 3 moves on the characteristic point 11a (step 301).

Then, the robot controller 9 outputs a drive command to the robot 1 and controls the drive of the robot 1 so that the sensor 3 scans under the scanning conditions taught in step 301. Simultaneously with the drive command, the sensor controller 6 outputs a detection command to the sensor 3 to start sensing by the sensor 3 (step 30
2).

The detection signal of the sensor 3 is amplified and output by the sensor amplifier 4, and the amplified signal is converted by the A / D converter 5 into the digital signal Z with a constant sampling period. Further, the tip position data P of the robot 1 is stored in the same address of the memory 14 of the robot controller 9 at any time.

Therefore, the CPU 7 of the sensor controller 6
Causes the digital displacement data Z output from the A / D converter 5 and the robot tip position data P stored in the memory 14 to be simultaneously stored in the memory 8 at regular intervals. At this time, the displacement data Z and the robot tip position data P are stored in association with each time.

In this way, the robot scanning system and the sensor measuring system are synchronized by simultaneously storing data in the memory 8 (step 303).

Then, the sensor controller 6 performs noise removal, differentiation, threshold value processing, etc. on the displacement data Z of the sensor 3 in the same manner as in step 105 above, at the characteristic point detection time tf and the detection time tf. Displacement Z of sensor 3
Find f (step 304).

Then, the robot tip position data P corresponding to the feature point detection time tf obtained in step 304 is read from the memory 8 (step 305). Therefore, the sensor position R at the characteristic point detection time tf can be calculated based on the read robot tip position P. Then, the position (X, Y, Z) of the feature point 11a can be calculated based on the calculated sensor position R and the displacement Zf of the sensor 3 at the feature point detection time tf obtained in step 304. (Step 3
06).

Fourth Embodiment (FIG. 10) Next, an embodiment in which the measurement data of the welding line 11 is corrected based on the detection signal of the displacement sensor 3 will be described.

Now, the displacement sensor 3 is, as described above,
A sensor for detecting the distance (displacement) between the sensor position R and the irradiation position PL by one-dimensionally detecting the reflection position when the laser beam J is irradiated on the work surface 10a as shown in FIG. Based on the robot tip position P (that is, the torch tip position 2a) based on the position of each axis of the robot 1 at the time of detecting the distance and the sensor position R, the irradiation position of the laser beam in the robot coordinate system, that is, the welding line 21.
Position PM is detected.

However, the irradiation position PM is set when the sensor 3 is mounted at a reference sensor position where the robot tip posture axis G which is the torch axis center and the projection laser optical axis (reference axis) H are parallel to each other. Is detected with high accuracy, but when the sensor 3 is mounted with a deviation from the reference sensor position, an optical axis deviation α occurs, and between the actual irradiation position PL and the calculated irradiation position PM. , A detection error ε will occur.

Therefore, in this embodiment, the above detection error is corrected by the processing procedure as shown in FIG. The processing contents of FIG. 10 will be described below with reference to FIG. That is, first, prior to the correction process, as shown in FIG. 9, a reference edge on which the coordinate position PE in the robot coordinate system XZ is measured in advance is set on the work 10.

Then, each axis of the robot 1 is driven, and the height Z of the sensor 3 is sequentially changed to different heights (level i = 0, 1, 2, ...
While sequentially changing to N), each axis of the robot 1 is drive-controlled so that the laser beam emitted from the sensor 3 scans the reference edge in the X direction for each height. Here, for the scanning of the sensor 3, the scanning method described in the above-described first embodiment or the like can be applied.

As a result, the scanning data Di indicating the correspondence between the robot tip position P based on each robot axis position and the output (sensor height) Z of the displacement sensor 3 for each height i.
(I = 0, 1, 2, ... N) is acquired. Note that each height i
It is assumed that the scanning conditions for each are taught in advance (steps 401, 402, 403).

Next, analysis processing is performed on the scan data Di, and characteristic data when the sensor height detection signal Z changes greatly is taken as the sensor height Zi at the time of detecting the reference edge. Then, the robot tip position Pi is associated with the sensor height Zi (step 404).

When the above process is completed for all heights (NO at step 405), the optical axis position parameters ΔSR, ΔSz, α for correction are calculated as follows based on the already detected data Pi, Zi. Is calculated.

That is, the distance between the robot tip position P and the sensor position R in the X direction is defined as ΔSR, and the distance between the robot tip position P and the sensor position R in the Z direction is defined as ΔSz.

Then, the deviation Xi in the X direction between the robot tip position Pi and the reference edge position PE at the time of detecting the above-mentioned reference edge.
Is obtained by the following equation: Xi = | Pi (x) -PE (x) | (8) (where the subscript (x) in the above equation represents the X coordinate component). Further, from the geometrical relationship, the relationship Xi = tan α · Zi + ΔSR (9) is established.

Therefore, regarding the above equation (9), Xi, Zi
Is performed by using the least squares method, and tan α and ΔSR are calculated as in the following equations (10) and (11).

[0070] For ΔSz, the data of one level is used and the following (12)
It is calculated by the formula.

ΔSz = Zi− | Pi (z) −PE (z) | (12) (In the above formula, the subscript (z) represents the Z coordinate component.) Thus, the optical axis position correction parameters ΔSR, ΔSz, tan
When α is calculated, these correction parameters, Z, which is the detection value of the displacement sensor 3, and the robot tip position P = [P (x), P (y), P (z)] at the time of the detection are calculated. , Laser light irradiation position PL = [P (x), P (y), P (z)] is calculated as follows.

PL (x) = P (x) + ΔSR + Z · tan α PL (y) = P (y) PL (z) = P (z) −ΔSz−Z (13) In this way, the optical axis deviation is corrected, and accurate. It is possible to detect a proper laser light irradiation position, that is, the position of the welding line (step 406).

[0073]

According to the present invention described above, the detection device is scanned without stopping the detection device on the characteristic point, all the distance data of the detection device is acquired, and the feature is calculated based on the acquired data. Since the scanning position of the detection device at the time of point detection is calculated, the position of the characteristic point can be obtained at high speed and with high accuracy regardless of the scanning speed. Therefore, the one-dimensional laser sensor can be used for detecting the position of the work, which enables a wide range of detection, and the cost can be dramatically reduced, and the position of the work can be detected at high speed and with high accuracy. become able to.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a robot system applied to an embodiment of the present invention.

FIG. 2 is a flowchart showing a procedure of processing executed by the robot controller and the sensor controller shown in FIG. 1, and is a flowchart showing processing contents of the first embodiment.

FIG. 3 is a diagram showing how a sensor scans a processing point in the first embodiment.

FIG. 4 is a graph showing detection values output from the sensor in time series with the scanning of FIG.

5 is a flowchart showing a procedure of processing executed by the robot controller and the sensor controller shown in FIG. 1, and is a flowchart showing processing contents of the second embodiment.

FIG. 6A is a diagram showing a state in which a sensor scans a processing point in the second embodiment, and FIG. 6B is a diagram showing FIG.
It is a graph which shows the detected value output from a sensor with a scan of (a) in time series.

FIG. 7 is a flowchart showing a procedure of processing executed by the robot controller and the sensor controller shown in FIG. 1, and is a flowchart showing processing contents of the third embodiment.

FIG. 8 is a diagram for explaining a fourth embodiment, and is a diagram for explaining a state of optical axis deviation of laser light emitted from the displacement sensor when the displacement sensor of the embodiment is mounted on a welding torch. Is.

FIG. 9 is a diagram for explaining how a reference edge is provided on a laser light irradiation surface to correct an optical axis shift.

FIG. 10 is a flowchart showing a processing procedure for correcting the position of the welding line according to the fourth embodiment.

[Explanation of symbols]

 1 Robot 3 1-dimensional laser displacement sensor 6 Sensor controller 9 Robot controller

Claims (4)

[Claims] 1. A detection device for detecting a distance to a surface of a work is positioned on a feature point of the work, the distance between the detection device and the feature point is detected by the detection device, and the detected distance is detected. In a work position detection device that detects the position of the feature point based on the position of the detection device and the position of the detection device, the detection device teaches the movement of the detection device so as to move across the feature point, and Therefore, the workpiece position detecting device is configured to calculate the position of the characteristic point based on the detected distance data of the detecting device acquired when the detecting device is moved and the teaching data. 2. A detection device for detecting a distance to a surface of a work is positioned on a feature point of the work, the distance between the detection device and the feature point is detected by the detection device, and the detected distance is detected. And a position of the detection device for detecting the position of the feature point based on the position of the detection device, the detection output of the detection device is changed at at least one point of the moving position, and the detection device is the feature point. The movement of the detection device is taught to be moved across, and the detection output of the detection device is detected based on the detection distance data of the detection device acquired when the detection device is moved according to the teaching data. The moving time of the detection device from the change time point to the characteristic point detection time point is calculated, the calculated movement time, the teaching position of the detection output change point of the detection device, and the detection Position detecting device of a work which is adapted to calculate a position of the feature point based on the moving speed and the moving direction of the location. 3. A detection device for detecting a distance to a surface of a work is positioned on a feature point of the work, the distance between the detection device and the feature point is detected by the detection device, and the detected distance is detected. And a position of the detection device for detecting the position of the feature point based on the position of the detection device, the detection output of the detection device is changed at at least one point of the moving position, and the detection device is the feature point. The movement of the detection device is taught to be moved across, and the detection output of the detection device is detected based on the detection distance data of the detection device acquired when the detection device is moved according to the teaching data. The moving distance in the detection output change direction of the detection device from the change time to the feature point detection time is calculated, and the calculated movement distance and the detection output change point of the detection device are taught. Position and the detecting device position detecting device of a work which is adapted to calculate a position of the feature point on the basis of the moving direction of the. 4. The detection device is taught in two different directions, and based on detection distance data of the detection device acquired when the detection device is moved according to the two teaching data, The work position detecting apparatus according to claim 3, wherein the moving distance in the detection output changing direction is corrected.