JPH0448304A - Method and device for correcting position of self-traveling robot - Google Patents

Abstract

PURPOSE:To quickly and accurately correct the position of a self-traveling robot by correcting the position of the robot arm in accordance with the relative positional error between an unmanned carrier and a work station and also the relative positional error between the robot arm and the work station. CONSTITUTION:The position of a robot arm 2 is corrected in accordance with the relative positional error between an unmanned carrier and a work station 3 an well as the relative positional error between the arm 2 and the station 3. Thus the position of the arm 2 is corrected with no addition of the arm 2 and regardless of a fact whether the arm 2 is holding a work 30 or not. Then the increase of the working cycle time can be suppressed for the arm 2. As a result, the relative positional error between a self-traveling robot and the station 3 can be surely corrected with high accuracy.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a self-propelled robot in which a robot arm grasps a workpiece from a work station or transfers the grasped workpiece to a work station. The present invention relates to a method and apparatus for correcting the position of a self-propelled robot, which positions the robot with respect to a work station with high precision.

[Conventional technology]

A self-propelled robot has an automated guided vehicle and a robot arm mounted on the automated guided vehicle, and when the automated guided vehicle moves to a work station position, the robot arm grasps a workpiece in the work station or removes the grasped workpiece. and hand it over to the work station. At that time, at the actual work site, the slope of the traveling road surface, the position of the robot arm, etc.
If the position of the load on the robot arm shifts due to a change in posture, the automatic guided vehicle will tilt and the accuracy of the stopping position at the work station will be disrupted, so it is necessary to consider the tilting of the automatic guided vehicle and the accuracy of the stopping position, etc. There is,
Therefore, the relative position between the self-propelled robot and the work station can be kept within a desired accuracy using the position correction means.

Examples of conventional technologies for position correction means for self-propelled robots include Japanese Patent Application Laid-open No. 60-237504 (hereinafter referred to as the first prior art) and Japanese Patent Application Laid-open No. 62-49521 (hereinafter referred to as the second prior art). ) is the technology shown below.

In the first conventional technology, a detection rod is provided in advance on the automatic guided vehicle of the self-propelled robot, and a reference surface is provided on the work station, and when the self-propelled robot moves to the work station, the automatic guided vehicle is detected. By pressing a rod against the work station and measuring the amount of movement of the detection rod, the amount of relative positional deviation between the work station and the self-propelled robot is detected. The system is configured to operate the robot arm of a self-propelled robot.

In the second conventional technology, a self-propelled robot is provided with a visual sensor, and when the self-propelled robot moves to a work station, the visual sensor recognizes the shape of a reference mark (or workpiece) on the work station and determines the position. The amount of deviation is detected, and if there is any deviation, the position of the self-propelled robot is corrected according to the amount of deviation.

Furthermore, as a third conventional technology, a self-propelled logat is provided with one visual sensor and two reference marks are provided on the work station, and as shown in FIG. 6(b), the automatic guided vehicle When moving to the work station and the robot arm moves to the reference position of the work station, - vision sensors detect one reference mark to perform the first position correction of the robot arm, and then the vision sensors detect the other reference mark. Some robot arms perform a second position correction by detecting fiducial marks to deliver a workpiece to a work station, then receive another workpiece from the work station and return to the original position.

[Problems to be Solved by the Invention] By the way, the first, second, and third prior art techniques shown above do not take into account the following points.

That is, in the first prior art, when the detection rod attached to the automatic guided vehicle detects the amount of relative positional deviation between the self-propelled robot and the work station, the position of the robot arm is corrected. A mechanical error of the robot arm is added to the correction, and therefore, even if the correction is made, the accuracy will deviate by one mechanical error, so there is a problem that it is difficult to correct the position with high precision.

The problem with the second conventional technology is that the visual sensor is attached to the hand of the robot arm of the self-propelled robot, and the visual sensor must also include the stopping accuracy of the automatic guided vehicle, making it impossible to obtain sufficient position correction accuracy. There is. Therefore, it is easy to consider reducing the field of view of the vision sensor in order to obtain sufficient position correction accuracy, but in that case, if you try to place the reference mark of the work station within the field of view of the vision sensor, , there is a problem that the search time is too long and it takes a long time to correct one position. Further, since only one visual sensor is provided, there is a problem in that it is difficult to ensure parallelism of the automatic guided vehicle with high precision. moreover,
When a self-propelled robot moves to a work station, the robot arm first corrects the position without holding the workpiece, and then the robot arm carries out the workpiece processing operation while holding the workpiece, which increases the robot arm's operation cycle time. However, there is also the problem of reduced work efficiency.

The third prior art shown in FIG. 6(b) is different from the second prior art because - visual sensors detect two reference marks and correct the position of the robot arm each time. As with other techniques, there is a problem in that position correction takes too much time.

In view of the above circumstances, it is an object of the present invention to be able to correct the positional deviation with high precision and reliability even if there is a deviation in the relative position between the self-propelled robot and the work station, thereby improving work efficiency. It is an object of the present invention to provide a method for correcting the position of a self-propelled robot, which can improve the position of a self-propelled robot.Another object of the present invention is to provide a position correction device for a self-propelled robot, which can accurately implement the above-mentioned method.

[Failure to solve the problem]

In the position correction method of the present invention, when the automatic guided vehicle stops at the work station position, the amount of relative positional deviation between the automatic guided vehicle and the work station is detected, and the robot arm is adjusted according to the detected amount of deviation. The present invention is characterized in that the motion data of the robot arm is corrected, then the amount of relative positional deviation between the robot arm and the work station is detected, and the motion data of the robot arm is corrected in accordance with the detected amount of deviation.

Further, in the position correction device of the present invention, the first reference mark installed on either the automatic guided vehicle or the fixed part;
A first visual sensor installed on either the automatic guided vehicle or the fixed part and located at a position corresponding to the first reference mark, and a second visual sensor installed on either the robot arm or the work station. a reference mark, a second visual sensor provided on the other of the robot arm or the work station, and located at a position corresponding to the second reference mark; a first correction unit that calculates the amount of relative positional deviation between the two first visual sensors and their corresponding reference marks at the time, and corrects the motion data of the robot arm based on the amount; and a second correction unit that calculates the amount of relative positional deviation between the second visual sensor and the second reference mark and corrects the motion data of the robot arm based on the amount of deviation. It is said that

[Effect]

As described above, in the method of the present invention, the position of the robot arm 1 is corrected according to the amount of deviation in the relative position between the automatic guided vehicle and the work station, and the position of the robot arm and the work station is Since the position of the robot arm is corrected, there is no need to add mechanical errors of the robot arm as in the first conventional technology, and it also eliminates the problem of whether or not the robot arm is gripping the workpiece. Since the position correction is performed without any trouble, it is possible to prevent the operation cycle time of the robot arm from increasing as in the second prior art.

Furthermore, since the first position correction of the robot arm is performed when the automatic guided vehicle moves to the work station, the second position correction is performed after the robot arm moves to the reference position of the work station, as in the third conventional technology. Compared to a system in which corrections are made individually, the operation cycle time of the robot arm can be reduced and position corrections can be made quickly.

Further, in the device of the present invention, as described above, the first reference mark, the first visual sensor, the second reference mark, the second visual sensor, the first correction section, and the second correction section are provided. Therefore, the above method can be carried out accurately.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 6. Fig. 1 is a schematic perspective view showing an embodiment of a self-propelled robot for carrying out the position correction method according to the present invention, Fig. 2 is a perspective view of main parts showing a work station, and Fig. 3 is a main part of a robot arm. FIG. 4 is an explanatory diagram showing correction of the position of the self-propelled robot with respect to the work station;
FIG. 5 is a block diagram showing the function of the correction means, and FIG.
) is a time chart showing the operation of the self-propelled robot.

The self-propelled robot of the embodiment shown in FIG. 1 includes an automatic guided vehicle 1 and a robot arm 2 mounted thereon.

The automatic guided vehicle 1 is adapted to move between a stock part (not shown) of a workpiece 30 and a work station 3 by a guide rail 4.The 60-bottom arm 2 is, for example, an articulated type having three degrees of freedom. It moves to the stock part of the workpiece 30 and grips the workpiece 30,
Move directly to the work station 3, supply the work 30 to the work take-in part 2a of the work station 3, and take another work 30 from the work take-out part 2b of the work station 3, 30 is supplied to the stock section, so work 3
A hand 5 for grasping and releasing the grip is provided at the tip of the wrist.

The work station 3 is installed in the middle of the guide rail 4, and when the self-propelled robot moves, the robot arm 2
A workpiece 30 is received from hand 5, and another workpiece 3o is delivered to hand 5.

Also, when moving the self-propelled robot to work station 3,
When the position of the self-propelled robot relative to the work station 3 deviates, a position correction device (
(not shown) is provided.

The position correction device can be broadly classified into a first reference mark 6.
6', a first visual sensor 7, 7', a second reference mark 8, 8', a second visual sensor 9, and a correction means.

As shown in FIG. 2, the first reference marks 6,6' are arranged at appropriate intervals on the upper surface of the mark mounting plate 31 of the work station 3, and are displayed, for example, in the form of dots. The mark mounting plate 31 is fixed to the side of the work station 3 near the guide rail 4. As shown in FIG. 1, the first visual sensors 7.7' are mounted on both sides of the side surface of the automatic guided vehicle 1 on the side of the work station 3 in correspondence with the first reference marks 6.6'. , when the self-propelled robot moves to the position of the work station 3, the displacement of the position of the automatic guided vehicle 1 with respect to the work station 3 is detected by projecting the corresponding first reference mark 6,6' within the range of each field of view. It is made to be able to be detected, and is made up of, for example, a TV camera.

As shown in FIG. 2, the second reference marks 8, 8' are arranged on the upper surface of the work station 3 at a position on the guide rail 4 side corresponding to the centers of the taking-in part 2a and the workpiece taking-out part 2b, Like the first reference mark 6.6', it is displayed as a dot type. Second visual sensor 9
is built in the hand 4 of the robot arm 2, and is composed of a TV camera like the first visual sensor 7.7', and detects a positional deviation with respect to the second reference mark 871i or 8'. That's what I do.

To explain in more detail, the second visual sensor 9
As shown in Figures (,) and (b), it is built into the inner part of a cylindrical hand base 51- attached to the tip of the robot arm 2, and a second reference mark 9 is projected through an optical system to be described later. I'm trying to get it out. The optical system is hand base 5
1, a lens 52 disposed in front of the second visual sensor 9, a reflective mirror 53 disposed in front of the lens 52, and a peripheral portion of the hand base 51 corresponding to the reflective mirror 53. It consists of a transparent window 54 formed therein. Then, the automatic guided vehicle] is at work station 2.
3(b), the reflection mirror 53 passes through the transmission window 54 and marks the second reference mark 8 (8').
) is reflected, and the reflected second reference mark is imaged by the second visual sensor 9 through the lens 52, so that the second visual sensor 9 detects the deviation inscribed on the work station 3. ing.

In FIG. 3, reference numeral 45 denotes a pair of claws attached to the tip of the gripper 46 in the hand base 51, which are opened and closed by the parking motion of a motor (not shown) to grip or move the workpiece 30. A second reference mark 9 is built into the inner part of the reference mark 51 through an optical system which will be described later. The optical system includes, inside the hand base 51, a lens 52 disposed in front of the second visual sensor 9, a reflection mirror 53 disposed in front of the lens 52, and a reflection mirror 53 of the hand base 51.
and a transmission window 54 formed on the corresponding outer periphery. When the automatic guided vehicle 1 moves to the work station 2, the reflective mirror 53 reflects the second reference mark s (s') through the transparent window 54, as shown in FIG. The second reference mark is imaged by the second visual sensor 9 through the lens 52, so that the second visual sensor 9 detects the deviation with respect to the work station 3.

In FIG. 3, reference numeral 55 denotes a pair of claws attached to the tip of the gripper 56 in the hand base 51, which are opened and closed by the vertical movement of a motor (not shown) to grip or release the workpiece 30. I try to do it. 57 performs the second visual grasp release shell. 4
7 is the cable for the 20th vision sensor 9, 48 is the claw 45
This is the cable connected to the

On the other hand, when the first visual sensor 7゜7' detects the amount of deviation with respect to the first reference mark 6.6' when the automatic guided vehicle 1 moves to the work station 3, the correction means corrects the
The correction unit 10 calculates the amount of deviation. For example, when the automatic guided vehicle 1 moves to the work station 3 as shown in FIG. 4 and stops, the center O' of the automatic guided vehicle 1 is set as the origin, and the first visual sensor 7. Field of view 7a, 7a'
Ml (xt' + y, + ) HM2 (X2'
+3'z'), the -th correction unit 10 has a deviation Δ
Find X, Δy, and O from the following equations.

θ=jan” Yz, -Yx, (X%≠X,')X2
-X.

(However, when I:=X21, only parallel movement)\y,=-x,'s□. θ ten a, 'CO5θ Yt
.= That's what I do.

Further, the correction means corrects the motion data of the robot arm 2 by the detection by the first visual sensors 7, 7', and then
When the robot arm 2 is moved to the second reference mark 8 (8') and the second visual sensor 9 detects a positional deviation with respect to the second reference mark 8 (8'), the second correction unit 11 moves to the second reference mark 8 (8'). By measuring the center coordinates of the second reference mark 8 (8') from the reference position of the field of view of the second visual sensor 9, the work station 3 of the robot arm 2 is
Accordingly, the correction means calculates the relative positional deviation between the automated guided vehicle 1 and the work station 3, and corrects the movement data of the robot arm 2 according to the amount of deviation. a first correction unit 10 that calculates the amount of deviation between the robot arm 2 and the work station 3 and corrects the position of the robot arm according to the amount of deviation; and a second correction section 11 for correcting the position of the robot arm 2 (see FIG. 5).Next, an embodiment of the method of the present invention will be described in relation to the operation of the self-propelled robot of the embodiment.

For example, when the robot arm 2 grips the workpiece 30 and the automatic guided vehicle 1 moves to the work station 3 and stops, the first visual sensor 7.7' detects the workpiece as shown in FIG. 6(a). First fiducial mark at station 36.
6' is detected. At this time, the -th correction section 10 of the correction means
calculates the amount of relative positional deviation between the automatic guided vehicle 1 and the work station 3 based on the detection, and corrects the position of the robot arm 2 according to the amount of deviation, so that the robot arm 2 moves as shown in Fig. 6(,). As shown in the waveform shown in FIG.

When the robot arm 2 moves to the reference position of the work station 3 in this way, the second visual sensor 9 moves as shown in the waveform shown in FIG. (8') is detected. At this time, the second correction unit 11 of the correction means calculates the amount of relative positional deviation between the robot arm 2 and the work station 3 based on the detection, and corrects the position of the robot arm 2 again according to the amount of deviation. .

Then, when the position of the robot arm 2 is corrected by the correction means, the robot arm 2 moves as indicated by the diagonal line waveform shown in FIG. , the work 30
By releasing the grip, the workpiece can be fed into the receiving section 2a. Note that when the robot arm 2 supplies the workpiece 30 to the receiving section 2a, it moves to the work station 3.
When the automatic guided vehicle 1 returns to its original position, this operation is repeated from the beginning.

As described above, in the embodiment of the method of the present invention, the position of the robot arm 2 is corrected according to the amount of relative positional deviation between the automatic guided vehicle 1 and the work station 3, and the position of the robot arm 2 is
Since the position of the robot arm 2 is corrected according to the amount of deviation in the relative position between the robot arm 2 and the work station 3, there is no need for mechanical errors of the robot arm to be added as in the first prior art, and moreover, the robot arm 2 is Since the position correction is performed regardless of whether or not the workpiece 30 is being gripped, it is possible to prevent the operation cycle time of the robot arm from increasing as in the second prior art.

Furthermore, since the relative position of the automatic guided vehicle 1 and the work station 3 is determined based on the two first visual sensors 7 and 7', a positional deviation of the automatic guided vehicle 1 with respect to the work station 3 may occur. Even if the field of view for detecting the deviation between the robot arm 2 and the work station 3 is narrowed, the deviation can be reliably and quickly determined.

Furthermore, when the automatic guided vehicle 1 moves to the work station 3, the first position correction of the robot arm 2 is performed based on the detection by the first visual sensor 7,7'.
The operation cycle time of the robot arm 2 is reduced compared to the third prior art shown in b) in which the position is corrected twice after the robot arm moves to the reference position of the work stage 3. As a result, 8T
The position can be corrected quickly by a time of .

Further, in the position correction device of the embodiment, the second visual sensor 9
is built into the hand 5 of the robot arm 2, so
Not only does the second visual sensor 9 not come into contact with the robot arm itself, but also interference with things around the work station 3 can be prevented. Moreover, since the second visual sensor 9 is hermetically built into the robot arm 2, dust generated within the robot arm 2 will not leak outside, making it ideal for cleaning indoor spaces such as semiconductor manufacturing sites. Can be fully applied to clean rooms to maintain high temperature.

In the illustrated embodiment, the robot arm 2 supplies a workpiece 30 to the workpiece take-in section 2a of a work station 3, and then takes out another workpiece 30 from the workpiece take-out section 2b of the work station 3. Although the present invention is not limited to this example, it goes without saying that the present invention can also be used to either supply or take out workpieces 30 to one work station 3. In the illustrated embodiment, the first reference mark 6.
6' is provided at work station 3, but
Since the work stage 3 is fixed, it is installed in a place other than the 1 work station, for example, on the road surface of the automatic guided vehicle 1 or on a fixed part such as the ceiling, and it is detected by the first visual sensor 7.7'. A similar effect can be obtained by doing so.

〔Effect of the invention〕

As described above, according to claim 1 of the present invention, the position of the robot arm is corrected according to the amount of deviation in the relative position between the automatic guided vehicle and the work station, and Since the position of the robot arm is corrected according to the amount of positional deviation, there is no need for mechanical errors of the robot arm to be added.Furthermore, the position is corrected regardless of whether or not the robot arm is gripping a workpiece. It is possible to suppress an increase in the operation cycle time of the robot arm, and the position can be corrected quickly and accurately, which has the effect of increasing work efficiency. Further, according to claim 2, since the amount of relative positional deviation between the automatic guided vehicle and the work station is determined based on two locations, even if a positional deviation occurs between the automatic guided vehicle and the work station, the deviation can be reliably canceled. From being able to.

Even if the field of view for detecting the deviation between the robot arm and the work station is narrowed, the effect is that the amount of deviation can be determined quickly and reliably.

According to claim 3, since the configuration includes the first reference mark, the first visual sensor, the second reference mark, and the second visual sensor, the effect of accurately implementing claim 1 is obtained. There is. Further, according to claim 4, since the first reference mark and the first visual sensor are comprised of at least two pieces, claim 2 can be implemented accurately, and further according to claim 5, Since the second visual sensor is built into the hand of the robot arm, it is possible to reliably prevent the second visual sensor from interfering with other objects. Since it is installed in a sealed manner, dust inside the robot arm will not leak outside.
The effect is that there is no risk of contaminating the room.

[Brief explanation of drawings]

FIG. 1 is a schematic perspective view showing an embodiment of a self-propelled robot for implementing the position correction method according to the present invention, FIG. 2 is a perspective view of main parts showing a work station, and FIGS.
b) is a cross-sectional view and a vertical cross-sectional view showing the main parts of the hand of the robot arm, FIG. 4 is an explanatory diagram showing correction of the position of the self-propelled robot with respect to the work station, and FIG. 5 is a block diagram showing the function of the correction means. 6(a) is a time chart showing the operation of a self-propelled robot, and FIG. 6(b) is a time chart of a self-propelled robot equipped with a conventional position correction device. 1 ・Automated guided vehicle, 2... Robot arm, 3...
Work station, 5 Hand, 6, 6'... First reference mark, 7, 7' - First visual sensor, 8° 8'
...Second reference mark, 9...Second visual sensor, 5
1. Hand base, 52. Lens, 53. Reflection mirror, 54. Transmission window. 1-A detailed car for Akira? -・0 SHOIT 7- TO 5- HUNT “ 7, 7'--° Taku- no Jōsenri 30-・17-7 5-... HUNT” 5I・-HA, TOPHE 52...・Shinku ゛53-・Reflection mirror 1st δ, 8- 30-・Pursuing me Second reference mark Second visual t>Sour work first corner

Claims (1)

[Claims] 1. An automated guided vehicle and a robot arm mounted on the automated guided vehicle, the automated guided vehicle is moved to a work station position, and the robot arm grasps or grasps a workpiece from the work station. In a self-propelled robot that transfers a workpiece to a work station, when the automatic guided vehicle stops at the work station position, the amount of relative positional deviation between the automatic guided vehicle and the work station is detected, and the detected amount of deviation is detected. The motion data of the robot arm is corrected according to the amount of deviation, the amount of relative position deviation between the robot arm and the work station is detected, and the movement data of the robot arm is corrected according to the detected amount of deviation. Characteristic position correction method for self-propelled robots. 2. The automatic guided vehicle according to claim 1, characterized in that when the automatic guided vehicle stops at the work station position, the amount of relative positional deviation between the automatic guided vehicle and the work station is determined based on at least two positions. How to correct the position of a running robot. 3. In a self-propelled robot that has an automated guided vehicle and a robot arm mounted on the automated guided vehicle, a first reference mark installed on either the automated guided vehicle or the fixed part, and the automated guided vehicle and the fixed part a first visual sensor disposed on either the robot arm or the work station and located at a position corresponding to the first fiducial mark; a second fiducial mark disposed on either the robot arm or the work station; A second visual sensor is provided on either the arm or the work station, and is placed at a position corresponding to the second reference mark; a first correction unit that calculates the amount of relative positional deviation between the first visual sensor and the corresponding reference mark, and corrects the movement data of the robot arm based on the amount of deviation; and a second visual sensor. A position of a self-propelled robot, characterized in that the self-propelled robot has a second correction section that calculates the amount of relative positional deviation between the reference mark and the second reference mark, and corrects the motion data of the robot arm based on the amount of deviation. correction device. 4. The position correction device for a self-propelled robot according to claim 3, wherein the first reference mark and the first visual sensor include at least two pieces. 5. The position correction of a self-propelled robot according to claim 3, wherein the second visual sensor is built into the robot arm and configured to be able to image a second reference mark located outside the robot arm. Device. 6. The position correction device for a self-propelled robot according to claim 5, wherein the second visual sensor is hermetically built into the robot arm.