JPS6218316B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to industrial robots.

An industrial robot that operates based on pre-stored information and has a movable arm consisting of a plurality of movable parts, that is, a teaching playback type industrial robot, and a working part fixed to the tip of the arm. Industrial robots having the following are known.

When it is necessary to operate this type of industrial robot with high precision, for example, when applying this robot to sealing work on automobiles where the robot's working part is in contact with the workpiece and follows the target work line, playback is required. The relative positions of the movable parts of the robot during teaching and the relative positions of the movable parts during teaching,
Due to errors, errors in positioning the workpiece, and errors in the shape of the workpiece itself, there is a risk that an error will occur in the trajectory of the robot's working part relative to the workpiece during playback.

The relative position (misalignment) of the working part of the robot with respect to the workpiece is detected, and in order to correct the deviation, the mutual positions of the movable parts of the movable arms of the robot are set based on pre-stored data. A so-called sensor-type industrial robot that corrects position is also known.

However, with this type of robot, it is necessary to perform complicated calculations (so-called coordinate transformation calculations) to find the corrected position of the arm, which has many degrees of freedom, and it takes a lot of time to control the robot's position. First, by applying such correction, the mutual positions of the movable parts of the robot arm deviate from the teaching position, so it is difficult to ensure smooth playback of the arm.

The present invention has been made in view of the above points, and its purpose is to provide an industrial robot that can operate at relatively high speed and with high accuracy.

It is an object of the present invention to provide a movable arm that performs a displacement operation based on information stored in advance, a working part that is movable with respect to the arm and is provided at the tip of the arm, and a working part that works on a workpiece. means for detecting a deviation between a first position of the tip of the workpiece and a second position at which the work is to be performed on the workpiece; In order to compensate for the deviation detected by the detection means, the working part is directly displaced relative to the arm by the deviation signal itself from the deviation detection means, and the working part is moved between the first position and the second position. and a means for matching the position with the
The means for detecting the shift includes a light source that projects an image onto the workpiece including the second position, and a light source that projects an image onto the workpiece including the second position;
An industrial robot comprising a television camera for capturing an image projected onto the workpiece including the position of will be achieved.

Next, a preferred specific example of the present invention will be explained based on the drawings.

In the figure, reference numeral 1 denotes a robot body consisting of a base 2 and a movable arm 3. The movable arm part 3 is A with respect to the base 2.
a disk portion 4 that is rotatable in the direction;
a first arm portion 5 that is rotatable in the direction B relative to the first arm portion 5;
It consists of a second arm part 6 that is rotatable in the C direction with respect to the first arm part 5, and a so-called elephant nose type wrist part 7 that is rotatable in three directions with respect to the second arm part. The position of the arm section 3 of the robot body 1, that is, the relative position of the disk section 4 with respect to the base 2, the relative position of the first arm section 5 with respect to the disk section 4, and the relative position of the second arm section 6 with respect to the first arm section 5. The relative position of the wrist portion 7 with respect to the second arm portion 6 is sequentially set based on a series of data stored in advance in a storage device (not shown).

A bracket 9 is attached to the cylindrical tip 8 of the wrist 7.
is fixed to the bracket 9, and another bracket 12 is provided on the bracket 9 via a connecting member 10 so as to be rotatable about the correction rotation axis 11. The bracket 12 includes a slit light source 15 for projecting the slit image 14 onto the work surface 13a of the work 13, a television camera 16 using a semiconductor image sensor or the like for capturing the slit image 14 on the work surface 13, and a robot body. 1 working part 17
is fixed. Reference numeral 18 denotes a rotation axis of the bracket 12 relative to the bracket 9. The rotation axis 18 is fixed to the camera 16 at the center, and is rotatably supported at both ends by the lateral protrusions 9a and 9b of the bracket 9. There is. A gear 19 is further fixed to one end of the rotating shaft 18, and a gear 19 is fixed to the output shaft of a reducer 21 connected to a highly responsive motor 20 such as a coreless motor fixed to the bracket 9. The other gear 22 that has been rotated is in mesh with it. Therefore, as the motor 20 rotates, the slit light source 15, the camera 16, and the working part 17 are rotated integrally around the axis 11.

23 is a potentiometer fixed to the bracket 9, and the potentiometer 23 is connected to the distance D between the bracket 9 and the bracket 12 (motor 20
(corresponding to the rotation angle of bracket 12 relative to bracket 9 about axis 11).

The light receiving optical axis 24 of the camera 16 In other words, the camera 1
The central axis 24 of 6 coincides with the central axis of the cylindrical tip 8 of the wrist 7, and preferably coincides with the rotational axis 11.
is perpendicular to The optical axis 25 of the slit light source 15 is oblique to the optical axis 24 and preferably oblique to the axis of rotation 11 . The working part 17 has a tip 26 that lightly contacts the work surface 13a, and the tip 26
a sealing nozzle 29 that dispenses a filler 28 from 6 to the sealing portion 27 of the workpiece 13; and an elastic member that elastically supports the nozzle 29 so that it can be displaced in the direction along the sealing direction E (front and back) and in the direction crossing this direction (left and right). The nozzle holder 30 consists of a rigid connecting portion 31 that maintains the nozzle holder 30 in a fixed position with respect to the bracket 12. The nozzle holder 30 can also absorb vertical errors of the tip 26 during playback. The nozzle 29 is in the same plane as the axes 24, 25, and the tip 26 of the nozzle 29 preferably intersects the axes 24, 25 at a point approximately simultaneously.

During teaching, the workpiece 13 is set at a predetermined position, the reversible motor 20 is set at the initial position, and the distance D between the brackets 9 and 12 is set to the initial distance.
D ₀ , the axis 11 is parallel to the seal line 27, the tip 26 of the nozzle 29, the axes 24, 25
is aligned with the seal portion 27 so that the axis 25 is located in front of the sealing direction E and the nozzle 29 is located at the rear in the sealing direction E, and the axis 24 is aligned with the work surface 1.
Position it perpendicular to 3. Thereafter, the tip portion 26 is displaced in the E direction so as to trace the seal portion 27 while keeping the distance D at D ₀ . The position of the arm portion 3 at this time is sequentially stored in a storage device (not shown) as teaching data.

The cross section of the seal portion is an upper overlap 32a, a lower overlap 32b,
In the case of the butt 32c, V groove 32d, and upper hole 32e, the light source 15 and camera 1 are
6. If the nozzle 17 is in the proper position with respect to the work surface, the slit images 33a, 33b,
33c, 33d, and 33e are obtained by camera 8.
Note that the arrow F is the direction of the optical axes 24 and 25, and 34 and 35 are the seal portion and the image of the seal portion, respectively.

During playback, if the position of the workpiece 13 having the overlapping seal portion 27 or the position of the wrist tip 8 of the robot body 1 is misaligned, the nozzle tip 26, which is the first position of the tip of the working part, and the covered The position of the point 50 on the seal line 27, which is the second position to be worked in the working section, is shifted, and the camera 16 obtains an image 36 as shown in FIG. 4, for example.

In the image 36, the nozzle is affected by the deviation +F from the center position Y (approximately corresponding to the position of the nozzle tip 26) in the vertical direction of the screen of the seal line portion image 39 represented by the left end of the bent portion 38 of the image 37 of the slit image. The positional deviation between the tip 26 and the seal line 27 is shown, and the magnitude of this deviation is detected by an image processing device as means for generating a deviation signal, and is output as a deviation signal.

It should be noted that the nozzle tip 26 is slightly deviated upward from the work surface 13 due to the deviation G of the center 41 of the bending part 38 in the horizontal direction in the left direction from the screen center position X in the image 36, and the image 37 is tilted with respect to the screen, it can be seen that the axis line 11 is tilted with respect to the seal line 27.

This deviation of the nozzle tip 26 from the seal line 27 is caused by the rotation of the motor 20 causing the nozzle 29 to move along the axis 11 along with the light source 15 and camera 16.
The adjustment is made by rotating the nozzle tip 26 in the direction J and displacing the nozzle tip 26 in the direction J perpendicular to the seal line direction E.

Next, the correction control mechanism 42 during playback will be explained in more detail.

The correction control mechanism 42 has two feedback loops 43 and 44. The large loop 43 performs basic positioning of the nozzle tip 26 with respect to the seal line 27 with high accuracy, and the small loop 44 performs basic positioning with high accuracy. In combination with the large loop 43, fast and accurate alignment is ensured.
In loop 43, the position of arm 3 is determined based on teaching data K. At the start of playback, the initial position L of the nozzle tip 26 is determined based on the position of the dead arm 3 with the distance D=D ₀ based on the data K.

The relative position of the nozzle tip 26 with respect to the seal line 27 when the nozzle tip 26 is at position L is imaged by the camera 16 paired with the slit light source 15, and the position of the nozzle tip 26 relative to the seal line 27 is determined based on the captured image.
If there is a deviation from 1 to the seal line 27, the direction and size F of the deviation are detected by the image processing device 40, and outputted from the device 40 as required correction amount data M. This data M is given to the motor 20 via the servo amplifier 45. The amplifier 45 rotates the motor 20 in a predetermined direction based on the data M, thereby displacing the nozzle tip 26 of the working part 17 toward the seal line 27 in a direction J perpendicular to the seal line. J of the tip 26
The relative position of the tip 26 with respect to the seal line 27 due to the directional displacement is imaged by the camera 16, and based on the imaged image, the presence, direction, and magnitude of the deviation F from the reference position are detected again by the device 40. , loop 43 until tip 26 coincides with seal line 27
processing is performed.

If the above correction operation speed of the loop 43 is sufficiently large compared to the moving speed of the nozzle tip 26 in the sealing line direction E, that is, the sealing work speed, then even just the loop 43 can actually keep the tip of the nozzle at all times during the sealing work. In order to move the portion 26 along the seal line 27,
Correction of the position of the tip 26 may be performed.

This is not only because the degree of freedom of the tip 26 with respect to the arm 3 is reduced, but also because the position of the arm 3 with respect to the base 2 is controlled by teaching data, and the actual working line 27 of the nozzle tip 26 is controlled. This is because the position of the nozzle tip 26 is controlled independently of the arm 3 so as to compensate for the deviation F relative to the arm 3.

However, the normal image processing device 40 is configured to recognize the video pattern of the slit image by converting the image into digital data and detect the deviation F. There are cases where it is necessary to make the moving speed of the nozzle tip 26 relatively large compared to the processing time for one sampling image, and to perform the sealing operation at high speed.

Even in such a case, since the correction mechanism 42 is provided with the small feedback loop 44, accurate correction can be performed.

That is, when correction data M for one sampling is output from the device 40, this data M
is held in the one-way comparator 46. The motor 20 is rotated via the amplifier 45 based on the correction data M held by the comparator 46, and the hand portion 26 of the working unit 17 is moved in the J direction. The displacement of the hand portion 26 is detected by the potentiometer 23 as a change in the distance D between the brackets 9 and 12, and the comparator 46 compares whether the amount of change in the distance D corresponds to the data M.

Note that, for example, the comparator 46 holds the current detection value _D1 of the potentiometer 23 every time new correction data M is input from the device 40, and also stores the distance data _D1 and J of the nozzle tip 26. Distance data D ₂ between the brackets 9 and 12 newly output from the potentiometer 22 along with the directional displacement (at the time the correction data M is output from the device 40, D ₂ =D ₁
), and compare whether this difference N corresponds to M.

The processing in this loop 44 continues until N corresponds to M, but since the response speed of this loop 44 can be made sufficiently faster than the processing speed of the processing device 40 and the sealing operation speed, the nozzle tip 26 can in fact be quickly displaced by the device 40 to a specified position. When the correction data M based on the sampling of the next image is output from the device 40, the loop 44 repeats in rapid response to displace the tip 26 based on the correction data M.

The industrial robot configured as described above has the following advantages.

(1) Teaching error, workpiece positioning error,
Regardless of the repetition error of the robot, the trajectory error during playback can be kept below a certain error determined by the correction mechanism.

(2) Correcting operations can be performed simply by adding a movable working part and a means for detecting and controlling the position of the working part to the wrist of a normal six-degree-of-freedom robot that does not have a sensor.

(3) Since this method does not correct the robot's posture (arm position) based on sensing results, coordinate transformation is not necessary. This eliminates the need for high-speed calculation functions and enormous coordinate conversion programs.

(4) Since the sensor detects only the distance from the seal line to the sealing nozzle tip,
The processing time for sensing results can be shortened. Furthermore, a high-speed, large-capacity image processing device is not required.

(5) Since images that serve as templates are not stored during teaching, the memory capacity can be the same as that of conventional teaching playback robots.
up to the pattern) may be increased.

Incidentally, in order to displace the nozzle tip 26 of the working part 17 in order to correct its position, it is not necessarily necessary to perform a rotational displacement about the axis 11;
For example, the brackets 9 and 12 may be connected by a hydraulic cylinder device including a piston and a cylinder, so that the bracket 12 can be displaced linearly and laterally relative to the bracket 9.
Further, the direction of displacement does not necessarily have to be one direction; for example, a cylinder device or the like may be further provided between the bracket 9 and the wrist tip 8 so as to move the nozzle tip 26 forward and backward with respect to the work surface 13a. good.

It is clear that the above-described industrial robot can be used not only for sealing work but also for other industrial robots that require precision by changing the configuration of the working part.

As mentioned above, the industrial robot of the present invention includes a movable arm that operates based on pre-stored information;
A working part movably provided at the tip of the arm with respect to the arm, means for detecting a deviation between the position of the working part and the position of the worked part, and a working part for compensating for the deviation detected by the detecting means. Since a means for displacing is provided, it can operate at high speed and with high accuracy.

In the industrial robot of the present invention, while the working part performs work on the workpiece based on teaching data, the first position of the tip of the work part and the second position on the workpiece to be worked are determined. In order to compensate for the detected deviation, the deviation signal itself obtained from the deviation detection means is used to directly detect the deviation from the working part, independently of the pre-stored information. The arm has means for causing the first position and the second position to match by changing the position relative to the arm.

Therefore, in the industrial robot of the present invention,
The tip of the working part is moved along the working path in advance based on the teaching data, and the deviation between the position of the work part to be worked and the position of the working part tip is detected at each part of this path, and the work is performed based on this deviation. Unlike the method of correcting the path that the tip of the part should move and moving the corrected work path obtained by this correction to perform the work, the work is performed based on the teaching data while the work part is being moved. Detects the misalignment between the position to be worked and the tip of the working part,
Without performing correction calculation processing based on this amount of deviation, the working part is displaced relative to the arm based on this amount of deviation itself, regardless of the teaching data, and the position of the tip of the working part and the working position of the part to be worked are determined. Since it is configured to match the desired position, it has the advantage of being able to perform work at relatively high speed.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of an industrial robot according to a preferred embodiment of the present invention, FIGS. 2 a and b are explanatory diagrams of the working part of the robot in FIG. 1, and FIGS. 3 a to e and 4 are seals. FIG. 5 is a block diagram of the correction control mechanism. 3...Arm part, 8...Wrist tip, 11...Rotation axis line, 15...Slit light source, 16...Camera, 2
0... Motor, 23... Potentiometer, 40
...Image processing device, F...misalignment.

Claims (1)

[Claims] 1. A movable arm that performs a displacement operation based on pre-stored information, a working unit that is movable with respect to the arm and is provided at the tip of the arm, and a work that performs work on a workpiece. means for detecting a deviation between a first position of the tip of the part and a second position to be worked on the part to be worked;
In order to compensate for the deviation detected by the detection means while the work unit is working on the workpiece, the deviation signal itself from the deviation detection means is used to compensate for the deviation detected by the detection means, independently of the pre-stored information. means for directly displacing the working part with respect to the arm to match the first position and the second position; a light source for projecting the image, a television camera for capturing the image projected from the light source onto the workpiece including the second position, and a deviation signal is obtained by comparing the image obtained from the television camera with a reference image. An industrial robot consisting of means for generating. 2. The device according to claim 1, wherein the working part moves in one direction with respect to the arm part.