JP3369990B2 - Robot calibration method and device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for calibrating a robot used in an automated line for machining and assembling a work.

[0002]

2. Description of the Related Art Due to recent advances in robots, sensors and computer technology, a system for recognizing the position and shape of a work in a three-dimensional space, or measurement data obtained by such a system is used to transfer the work by a robot. Robot devices that automatically perform processing, assembly, etc. have been developed.

This type of robot apparatus has a function of holding and transporting a work by a hand adopting a chuckless method such as a suction or mounting method for a cylindrical or disk-shaped work, and placing it on a transfer destination. Have. The hand is equipped with an on / off sensor such as a photoelectric sensor that detects the edge of the work, and this detects that the hand has come close to the position where the work can be held.
Then, from that position to the center position of the work, by visually confirming whether or not the hand holds the center of the work, the correction amount of the position is obtained. Poor workability was a problem.

On the other hand, there is provided a work position automatic correction system which automatically adjusts the center position of a work held by a robot in accordance with the center position of a work storage part (work receiving part) which is a transfer destination. In this work position automatic correction system, normally, the positional relationship between the robot (hand) and the work (hence, the sensor for detecting it) must be known in advance. Therefore, it is necessary to obtain the positional relationship between the two (calibration) before using the system.

[0005]

However, in the conventional system using the robot, the position of the effector (effector) such as the machining tool or the cutting tool attached to the hand, and the position of the sensor for detecting the position and shape of the work. Since there is almost no systematic examination of the calibration method for measuring and adjusting the relationship with, and further the simplification or automation of the calibration,
The automation was not enough.

Actually, after a person visually measures or judges an adjustment result, directly or with the assistance of a camera visual field, etc.,
Calibration is often performed by repeating the operation of operating the robot and determining the result. Therefore, the conventional calibration work has a problem that it is difficult to obtain accuracy and it takes time.

Regarding the mounting position of the sensor as described above, it is often necessary to perform mechanical positioning, especially when a sensor for detecting the work position is arranged near the effector of the robot. The work area was small and the calibration work itself was difficult.

An object of the present invention is to have a function of detecting the center position of a work having a cylindrical shape or a disk shape and automatically adjusting the position of the work in accordance with the center position of the work receiving destination. In a robot system, a calibration method that automatically measures the relationship between the position of the sensor that detects the position of the work and the position of the robot that holds and conveys the work, and performs the necessary correction, and this And an apparatus for performing the same.

[0009]

According to the present invention, a hand part (2) for holding and transferring a work (W) to be transferred is provided.
And a work position detecting means (4, 5) for detecting an edge or a surface of the work (W), comprising: (a) the work (W) or a work equivalent thereto. A reference work (W ₀ ) having an outer shape in at least a part thereof is provided with a sensor unit (6, 12) for detecting the center of an object and the reference work (W ₀ ).
Detachable at a position that can reproduce the positional relationship with the
Smell inside the installed calibration unit (20)
The retained in the detection range of the sensor unit (6, 12), the hand portion (2) the sensor unit Te (6,1
Moving within the detection range of 2) and detecting the center position of the work (W) or the reference work (W ₀ ) and the hand part (2) by the sensor unit (6, 12), (b) The hand unit (2) is connected to the sensor unit (6,
Furthermore the workpiece from the detection position at 12) (W) or reference close to the workpiece _{(W 0),} the workpiece position detecting means (4, 5) of the workpiece (W) or reference workpiece _(W 0)
Moving to a position for detecting the edge or surface of the workpiece, and (c) the center position when the centers of the reference work (W) and the hand part (2) are aligned with each other, and the work position detecting means (4). 5) is the work (W) or the reference work (W ₀ ).
The method is characterized by including a step of calculating a distance from the position where the edge or the surface of is detected and storing the value as a correction value.

The apparatus of the present invention is provided with a work (W) to be transferred.
A device for calibrating a work transfer robot comprising a hand part (2) for holding and transferring the work and a work position detecting means (4, 5) for detecting an edge or a surface of the work. A sensor unit (6, 12) for detecting the center of an object that has entered the detection range, and the reference
Detachable at a position that can reproduce the positional relationship with the work
It comprises a calibration unit (20) arranged and a control means (computer) for controlling the operation of the hand part (2), the control means (computer) comprising:
The reference work (W ₀ ) having at least a part of the work (W) or an outer shape equivalent to the work (W) is used for the calibration.
Sensor unit (6, 1 in the unit unit (20)
The hand part (2) is moved within the detection range of the sensor unit (6, 12) while being held within the detection range of 2), and the hand part (2) and the workpiece are detected by the center position detecting means. (W) or after detecting the center position of the reference work (W ₀ ), the hand part (2) is brought closer to the work or the reference work than the detection position of the sensor unit (6, 12), Each of the work position detecting means (4, 5) and the sensor unit (6, 12) so that the position detecting means (4,5) moves to a position for detecting the edge or surface of the work or the reference work. The hand part (2) is controlled based on the detection signal, and the center position when the centers of the reference work (W ₀ ) and the hand part (2) are aligned with each other, and the work position detecting means (4,5). ) Is the word It is characterized in that the distance from the position where the edge or surface of the reference work or the reference work is detected is calculated and the value is stored as a correction value.

In the present invention, a reference work having a shape similar to the work as described above and the reference work are provided.
It was removably placed at a position where the positional relationship could be reproduced.
By using the sensor unit capable of detecting the center of the object within the detection range in the calibration unit, the relative positional relationship between the robot and the work position detection sensor can be easily obtained.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is directed to a robot for holding, transporting and transferring a cylindrical or disk-shaped work by using a chuckless type effector of a suction type or a loading type, and a central position of the work. It can be used for the "work position automatic correction system" that automatically adjusts the center position of the work held by the robot to the center position of the work receiver (work receiving) to which the robot is transferred using the sensor that detects Is.

The case where a fork is used as an example of the "mounted effector" provided in the robot apparatus will be described below as the work position automatic correction system. A robot device using a fork is used, for example, in a process of assembling a back cover from the lower side of a wristwatch main body, a wafer replacement process in a semiconductor manufacturing process, and the like. That is, FIG. 1 shows an example of a process of assembling the back cover from the lower side of the wristwatch main body in the work of transferring the work to the work receiving portion installed at a predetermined position by the robot device.

Here, the work (back cover) W placed on the fork 2 at the tip of the robot apparatus 1 is transferred to the lower side of the wristwatch body T held by the work receiving portion 3 and is moved to a predetermined position. Attach to. Therefore, in this case, the mounting work is required after the center position of the wristwatch body T held by the work receiving portion 3 and the center position of the back cover W are matched. As a means for controlling such operations, a central processing unit (CPU) and a storage device (memory)
Computers including and are used. This is housed in the main body of the robot apparatus 1 or installed outside the main body.

In order to accurately transfer and place the work W in the work of assembling the work W as described above, the center position of the work W mounted on the fork 2 is set in the work receiving portion 3 which is the transfer destination. It is necessary to automatically adjust the position according to the center position, and as a prerequisite for that, it is necessary to perform calibration for obtaining the positional relationship between the robot and the sensor that detects the position of the work.

FIG. 2 shows an automatic work position correcting system according to an embodiment of the present invention, which has a built-in reference work W ₀ which can be placed on the fork 2 with its center position aligned, and which is located at the center of the object within the detection range. The calibration unit 20 capable of detecting the position will be described.

The calibration unit 20 includes
The center position detection sensor unit 6 is provided on the upper surface,
Within the detection range of the center position detection sensor unit 6, the reference work
Ku W ₀Is fixed. Here, the center position detection sensor unit
The knit 6 detects the center position of the object within the detection range.
It is a sensor that can be output, and in this embodiment, a CCD camera
The case where it is used is shown. This calibration unit
According to the cot 20, the fork 2 is transferred into this,
Steps within the detection range of the center position detection sensor unit 6
It is possible to detect the center position of the fork 2 on the floor
It

The reference work W ₀ is formed in a disc shape as shown in FIG. 2, and its outer diameter or radius is known. Here, it is assumed that the radius r of the reference work W ₀ is equal to the work (the back cover) used in the actual work. Therefore, the fork 2 is the disc-shaped reference work W.
A concave portion 2a having an arcuate portion along the circumference of the reference work W ₀ is formed so that ₀ can be placed and stored. The reference work W ₀ is fixed by four columns 7 standing on the reference work fixing base 8. The upper end of each column 7 has a groove-shaped notch formed on the inner side thereof for mounting and fixing the reference work W ₀ .

The fork 2 is provided on the side surface of the calibration unit 20 facing the fixed position of the reference work W _0.
An opening 21 is provided so that the inside of the calibration unit 20 can enter.

Next, the calibration unit 2
As shown in FIG. 1, the fork 2 used for 0 has a Z (vertical) direction position detection unit (hereinafter referred to as “Z detection sensor”) 4 in the robot coordinate system (X, Y, Z). XY
A detection unit (hereinafter referred to as “XY detection sensor”) 5 for position detection in the (plane) direction is attached.

The positional relationship between the respective detecting portions and the work when the fork 2 is brought close to the reference work W ₀ is shown in FIG. 3 for the Z detection sensor 4 and in FIG. 4 for the XY detection sensor 5. The “Z detection sensor” 4 includes a light emitting element and a light receiving element (not shown), and as shown in FIG. 3, by detecting the edge of the reference work W ₀ by the detection sections 4 on both sides, It is configured to detect the position of the work W _{0 in} the Z direction. As shown in FIG. 4, the “XY detection sensor” 5 is a U-shaped detection unit that sandwiches the surface of the reference work W ₀ , and includes, for example, a light emitting element on the upper side and a light receiving element on the lower side. It is configured to detect the position of W _{0 in} the XY directions.

In the work position automatic correction system using the calibration unit 20 as described above, calibration can be performed by performing the same operation as the work transfer work actually performed by the robot apparatus 1 in the calibration unit 20. It is what

Next, the calibration unit 2
A calibration processing procedure based on 0 will be described.

ST1: The fork 2 is moved within the detection range of the center position detection sensor unit in the calibration unit 20.

ST2: The center position detecting sensor unit 6 detects the center positions of the fork 2 and the reference work W ₀ ,
Memorize the relative position of both.

ST3: The fork 2 is moved to the vicinity of the reference work W ₀ .

ST4: The Z detection sensor 4 goes from OFF to O
The fork 2 is moved (raised) in the Z-axis (vertical) direction until it is switched to N (FIG. 3).

ST5: The robot is stopped when the Z detection sensor 4 is turned on, and the Z coordinate value (Z ₁ ) at this time is stopped.
Memorize

ST6: XY detection sensor 5 goes from OFF to O
The fork 2 is moved (advanced) in the XY (horizontal) directions until it is switched to N.

ST7: The robot is stopped when the XY detection sensor 5 is turned on, and its XY coordinate values (X ₁ , Y
₁ ) is memorized.

ST8: The positional relationship between the center of the fork 2 and the XY detection sensor 5 is calculated from the relative positions of the fork 2 and the reference work W ₀ stored in ST2 and the coordinate values (X ₁ , Y ₁ ).

The control unit operates the robot so that the positional relationship calculated by the above procedure is stored and the relative positional relationship between the stored center of the fork 2 and the XY detection sensor 5 is reproduced. To control. As a result, the center of the work receiving portion 3 and the center of the fork 2 can be easily aligned, and the robot apparatus 1 can perform reproducible and accurate work.

As a method of ensuring reproducibility when the calibration unit 20 is attached and detached without the center positions of the work receiving portion 3 and the reference work W ₀ being displaced, a pin is attached to the bottom of the calibration unit 20. It is possible to adopt a method in which the hole 9 is provided and the calibration unit mounting base 10 is provided with the pin 11 that fits into the pin hole 9.

As another example of the calibration unit 20 having the center position detection sensor unit, a scanner device may be used as the center position detection sensor unit. The scanner device can recognize the shape of the object by optically scanning the object and reading the reflected light. The scanner device as the center position detection sensor unit in the present embodiment is configured so that the center position of the object can be calculated from the recognized shape data.

FIG. 5 shows the calibration unit 20 when the scanner device 12 is used as the center position detection sensor unit.

The scanner device 12 is connected to an actuator 13 which is movable in the Y direction, and is configured to be movable in the Y direction with a movable range between AB shown in FIG. This movable range is the detection range of the scanner device 12 in the Y direction. Further, it is assumed that the scanner device 12 has a sufficient length in the X direction so that the scanner device 12 falls within the detection range when the scanner device 12 moves above the fork 2 and the reference work W ₀ .

Therefore, also in the calibration unit 20 using this scanner 12, by moving the fork 2 to the detection range of the scanner 12 and detecting the center positions of the fork 2 and the reference work W ₀ , the above-mentioned ST3 is performed. The calibration is executed by the processing procedure from ST8 to ST8.

According to the above, the automation of the calibration work for knowing the relative position between the robot device and the work position detection sensor can be realized. Further, the calibration work accompanying the replacement of the work position detection sensor or the robot effector is simplified, and the maintenance work is facilitated.

Further, the work position automatic correction system according to the present invention can be applied not only when using the above-mentioned on-board effector but also when using the suction-type effector.

Also, when teaching the center position of the work receiving part with respect to the center position of the robot effector using a work having a different outer diameter from the circumference of the reference work, the data obtained during calibration is used. If the relationship between the center position of the effector and the work position detecting sensor is obtained by utilizing the geometrical property, teaching becomes easy.

[Brief description of drawings]

FIG. 1 is a diagram showing a process of assembling a back cover to a wristwatch body by a robot device.

FIG. 2 is a diagram showing an example of a work position automatic correction system for carrying out the present invention.

FIG. 3 is a diagram showing a positional relationship between a reference work and a Z detection sensor.

FIG. 4 is a diagram showing a positional relationship between a reference work and an XY detection sensor.

FIG. 5 is a diagram showing another example of the work position automatic correction system.

[Explanation of symbols]

1 ... Robot device, 2 ... Fork, 3 ... Work receiving part, W
… Work, T… Watch body, W ₀ … Reference work, 4… Z
Detection sensor, 5 ... XY detection sensor, 6 ... CCD camera,
7 ... Posts, 8 ... Reference work mounting base, 9 ... Pin holes, 10 ...
Calibration unit mounting base, 11 ... Pin, 12 ... Scanner device, 20 Calibration unit.

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Claims (2)

(57) [Claims] 1. A calibration method for a work transfer robot, comprising: a hand part for holding and transferring a work to be transferred; and a work position detecting means for detecting an edge or a surface of the work. ) a reference workpiece having at least a portion of the workpiece or equivalent profile, Sensayu for detecting the center of the object
Have a knit and reproduce the positional relationship with the reference work
Calibration removably placed in place
Hold within the detection range of the sensor in the unit ,
A step of moving the hand unit within a detection range of the sensor unit to detect the center position of the work or reference work and the hand unit by the sensor unit; (b) the hand unit in the sensor unit A step of further approaching the work or the reference work from the detection position, and moving to a position where the work position detecting means detects the edge or surface of the work or the reference work, and (c) the center of the reference work and the hand part. A step of calculating a distance between the center position at the time of matching and the position where the work position detecting means detects the edge or surface of the work or the reference work, and storing the value as a correction value. Characterize. 2. A device for calibrating a work transfer robot comprising a hand part for holding and transferring a work to be transferred and a work position detecting means for detecting an edge or a surface of the work. Has a sensor unit for detecting the center of an object that has entered the detection range by
Detachable at a position that can reproduce the positional relationship with the
Comprising a calibration unit which is location, and control means for controlling the operation of the hand unit, said control means, the workpiece or which said reference workpiece having at least a portion the same outer shape and Kyaribureshi
In the state in which the hand unit is held within the detection range of the sensor unit, the hand unit is moved into the detection range of the sensor unit, and the center position detecting means detects the center positions of the hand unit and the work or the reference work. After that, the hand unit is brought closer to the work or the reference work than the detection position in the sensor unit, and the work position detecting means moves to a position where the edge or surface of the work or the reference work is detected, work
The hand portion is controlled based on each detection signal from the position detecting means and the sensor unit, the center position when the center of the reference work and the center of the hand portion are matched, and the work position detecting means is the work or It is characterized in that the distance between the edge of the reference work and the position where the surface is detected is calculated and the value is stored as a correction value.