JPH0790482B2 - Method of detecting groove position at the beginning of processing line - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a groove position detecting method of a machining line starting end, and particularly to a machining line starting end of a groove position to be machined, for example, in position control of a welding robot. The present invention relates to a groove position detection method of a processing line starting end suitable for detecting the positional deviation of the.

[Prior Art] As a conventional technology for welding a welding line on an object surface, a copying control method described in JP-A-58-209481 is known.

The technique is to irradiate a linear light flux, that is, a slit light in a direction orthogonal to the processing line direction, and to obtain a three-dimensional coordinate position of the groove from a light-section image obtained by an imaging device integrally configured with the slit light source. Had been detected. Then, the welding torch is moved in parallel along the deviation vector direction between the detected position and the teaching position, and the welding torch is moved along the machining line.

[Problems to be Solved by the Invention] With the above-described conventional visual sensor, only the groove position in the plane irradiated with the slit light can be detected, and the posture at the time of detection or the height of the workpiece No consideration has been given to the fact that the irradiation position of the slit light moves back and forth in the processing line direction due to the positional shift in the direction, and there is a problem that the position of the starting end to be processed is displaced in the processing line direction.

The present invention was made in order to solve the problems of the above-mentioned conventional techniques, without shifting the detection position in the processing line direction,
It is an object of the present invention to provide a method for detecting a groove position of a processing line starting end capable of detecting a groove position deviation of the processing line starting end.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the structure of the groove position detecting method of the machining line starting end according to the present invention has a robot having a teaching / reproducing function, a robot controller, and the robot. Of the robot controller, which includes a visual sensor fixed to the supporting shaft of the robot for detecting the position of the groove at the starting end of the machining line, and a machining means inclined and fixed with respect to the axis of the supporting shaft of the robot. In a method of performing a machining by correcting a positional deviation between a teaching position and a machining position using a function, first calculating a retreat point retracted from a teaching position of a machining line start end in a axial direction of a machining means by a constant distance. Step, a second step of moving the processing means tip to the retreat point, a third step of activating the visual sensor to detect the groove position of the processing start end, and a detection reference point of the visual sensor. Against In the fourth step of calculating the position deviation vector of the groove portion detected in the third step, among the position deviation vector, the rotation center axis of the robot support shaft and the axis of the processing means are Comprising a fifth step of calculating a position deviation vector component in the plane formed, and a sixth step of moving the support axis of the robot in the position deviation vector direction obtained in the fourth step, the fourth step The third step to the sixth step are sequentially repeated until the position deviation vector at zero becomes zero, and the position deviation vector component obtained at the fifth step at the time when the position deviation vector becomes zero is opened. This is the amount of deviation of the previous position.

[Operation] According to the method described above, the visual sensor is arranged in the plane formed by the rotation center axis of the robot support shaft and the axis of the machining means in the detected three-dimensional position deviation vector of the groove at the machining line start end. Since only the position deviation vector component of is transmitted to the robot controller, the support axis of the robot moves only in the plane, and therefore, when the position deviation vector becomes zero, the reference point of the visual sensor is , Coincides with the plane.

As a result, the present visual sensor can detect the groove position in the plane, so that the starting point of the machining line does not shift in the front-back direction of the machining line.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 to 11, taking the case of performing welding as an example.

First, the configuration of the position control device for the welding robot will be described with reference to FIGS. 1 to 4.

FIG. 1 is a side view of a robot supporting part of a welding robot according to an embodiment of the present invention, to which a visual sensor is attached, FIG. 2 is a front view of FIG. 1, and FIG. FIG. 4 is a schematic diagram showing the hardware configuration of the control system of the welding robot system.

In FIGS. 1 and 2, 1 is a visual sensor for detecting a groove position at a welding line starting end portion, 2 is a welding torch related to a processing means, 3 is a support shaft of a robot which is a position control means of the welding torch 2. Reference numeral 4 denotes the welding torch 2 and the support shaft 3 of the robot.
It is a mounting jig for fixing to.

6 is a slit light source for irradiating a slit-shaped light beam 5, for example, a semiconductor laser, 10 is a lens 7, a mirror 8,
And an optical system for observation, which is provided with a fixed image pickup device 9. The optical system for observation 10 observes a light section image formed on a member 11 to be measured, which is an object to be measured when the slit light source 6 is irradiated. Is. The slit light source 6 and the observation optical system 10 constitute the visual sensor 1.

The plane formed by the central axis of the slit light beam 5 and the central axis of the observation optical system 10 is configured to form a predetermined angle with the axial center of the processing means, that is, the central axis of the welding torch 2, and the slit light beam 5 The line that equally divides the angle formed by the central axis of the and the central axis of the observation optical system 10 and the axis of the welding torch 2 and the rotation center axis of the support shaft 3 corresponding to the robot wrist coincide,
A reference point O ′ of the observation optical system 10 is placed at a point extended in the axial direction of the welding torch 2 by an amount (for example, 10 mm) retracted from the tip position O of the welding wire incorporated in the welding torch 2.
The slit ray 5 is also adjusted so as to pass through this reference point O ′.

In the welding robot system shown in FIG. 3, 12 is a robot, 13 is a robot control device, 14 is a teaching operation panel, 18 is an image processing device, 19 is a console type teaching box, and 23 is a welding machine.

Robot 12, robot controller 13, and teaching pendant 14
Are connected by a cable. A visual sensor 1 and a welding torch 2 are fixed to a support shaft 3 of the robot, the visual sensor 1 is connected to an image processing device 18 by a signal cable 15, and the image processing device 18 is connected to a teaching box 19. .

The welding wire is supplied from the wire reel 20 to the welding torch 2 via the conduit cable 22. Also,
Wires are simultaneously welded through conduit cable 22 to welder 23
The shield gas is supplied from the gas cylinder 25 to the welding machine 23 via the cable 24, and the shield gas is guided to the welding torch 2 via the conduit cable 22.

The robot 12 is a vertical multi-joint type having five degrees of freedom due to rotary joints, and performs horizontal turning, upper arm rotation, forearm rotation, wrist bending, and wrist twisting from a joint near the base.
Although not shown, the power of the motor is transmitted to each joint via a speed reducer. The light section image obtained by the visual sensor 1 is sent to the image processing device 18, and the image processing device 18
The position of the welding line in the screen and the position in the wrist coordinate system based on the position are obtained from the light section image.

The hardware configuration of the control system of such a welding robot system will be described with reference to FIG.

In FIG. 4, the same reference numerals as those in FIG. 3 indicate the same devices and parts.

The robot controller 13 shown in FIG. 4 uses the mechanical interface 26 to communicate with the robot 12 and the welder interface 27.
Is connected to the welding machine 23. Robot controller 13
The inter-computer communication boat 28 and the image processing device 18 are connected by a serial signal line. Visual sensor 1
The slit light source 6 and the solid-state image sensor 9 are connected to the image processing device 18 via a sensor interface 29 by a signal cable 15 therein.

Next, a method for detecting a position deviation vector of a groove position at a welding start point by a welding robot equipped with such a visual sensor will be described with reference to FIGS.
A description will be given with reference to FIGS. 5 to 11.

FIG. 5 is an explanatory perspective view showing a method of teaching a welding path, and FIG.
FIG. 7 is an explanatory perspective view showing the reproducing operation, FIG. 7 is an explanatory view of the retracting operation, (a) is a perspective view, (b) is an enlarged view of the wire tip portion, and FIG. 8 is a light section image. Explanatory diagram showing the detection screen,
FIG. 9 is a perspective view for explaining the groove detection position at the welding start point and the moving position of the welding torch. FIG. 10 is a flowchart of robot operation at the detection point. FIG. 11 is detection progress at the detection point. FIG. 3 is an explanatory perspective view showing a movement path of the welding torch.

First, the processing line, that is, the welding path, on which the welding torch 2 corresponding to the wrist of the robot 12 is to be operated is set in the teaching box 19
To teach. That is, after teaching the approach point shown in FIG. 5 (a), at the welding start point in FIG. 5 (b), the sensor ON for detection by the visual sensor 1, the groove shape, the welding torch shift, etc. Teach. That is,
Teach data (for example, welding position) stored in advance in the storage unit (bubble memory) in the robot controller 13 such as types of welded joints, detection of positional deviation of the groove portion, and correction of the welding path based on the detection. , Posture, welding speed, welding current, etc.).

At the welding end point shown in FIG. 5 (c), the shift instruction is similarly added, and it is stored that the position of the path reaching the welding end point is corrected based on the detection data obtained at the welding start point.

After performing such a teaching operation, the reproducing operation is performed.

The robot 12 detects by the visual sensor 1, that is, a sensor.
It moves according to a previously taught path until the welding start point set to ON is reached.

At the sensor ON point, a retracting point shown in FIG. 6 (a) is created based on the position data for teaching the sensor ON, and the tip of the wire of the welding torch 2 is positioned at this point (step in FIG. 10).

A method of determining this retreat point will be described with reference to FIG.

In FIG. 7 (b), O'is a teaching point serving as a reference point of the observation system, and O is a retracting point at which the tip of the wire is retracted from the teaching point O'in the axial direction of the welding torch 2.

As shown in the figure, the position of the wire tip of the welding torch 2 after retreat, that is, the retreat point O is the origin, and the rotation center axis direction of the support shaft 3 of the robot passing through this origin is the Z'axis. Consider the coordinate system O-X'Y'Z 'of the welding torch 2 (wrist of the robot 12) in which the X'axis is set in the direction orthogonal to the Z'axis in the plane including the axis of the welding torch 2.

Assuming that the mounting angle of the welding torch 2 with respect to the coordinate system is 45 °, the retraction vector from the teaching point O ′ to the retreat point O Is the amount of evacuation, and Given in.

This evacuation vector Is the save vector in the robot coordinate system O-XYZ based on the following information based on the joint angle information of the robot. Can be converted to.

Here, the coordinate conversion matrix T is given as follows from each joint angle information at the time of teaching.

_{n x = C 1 C 234 C} 5 -S 1 S 5 n y = S 1 C 234 C 5 = + C 1 S 5 n z = -S 234 C 5 θ x -C 1 C 234 S 5 -S 1 C 5 θ _y = −S ₁ C ₂₃₄ S ₅ + C ₁ C ₅ θ _z = S ₂₃₄ S ₅ d _x ＝ C ₁ S _{234 dy} ＝ S ₁ S ₂₃₄ d _z ＝ C ₂₃₄ P _x ＝ C ₂ (d ₅ · D _{234 + a 3 · C 23 +} a 2 · C 2) p = S 1 (d 5 · D 234 + a 3 · C 23 + a 2 · C 2) p z = d 5 · C 234 -a 3 · S 23 -a 2 S ₂ Where Ci = cos θi (i = 1, ..., 5) Si = sin θi (i = 1, ..., 5) Cijk = cos (θi + θj + θk) Sijk = sin (θi + θj + θk) θ ₁ : Rotating joint rotation angle θ ₂ : Upper arm joint rotation angle theta _3: forearm joint rotation angle theta _4: wrist bending joint rotation angle theta _5: wrist twist joint rotation angle a _2: upper arm length a _3: forearm length d _5: a hand portion length.

The robot 12 moves the welding torch 2 to the retreat point O calculated by the equation (1) while maintaining the posture in the robot coordinate system at the time of teaching, and sends a detection command to the image processing device 18 together with information on the groove shape. .

The image processing device 18 captures the light section image obtained from the solid-state imaging device 9 by irradiating the slit light beam 5 from the slit light source 6, and as shown in FIG. 8, according to the recognition algorithm determined by the groove shape, that is, The position where the gradient of the line in the image changes is recognized as the position of the welding line, that is, the groove position, and the groove position (u, v) on the screen is obtained.

Since the visual sensor 1 uses the teaching point O ′ shown in FIG. 7 (b) as the reference point of the observation system, as shown in FIG. 9, the positional deviation up to the point S where the slit ray is radiated is shown. vector Can be obtained (step in FIG. 10).

Here, the irradiation center axis of the slit light beam 5 and the center axis of the imaging system of the light section image form an equal angle with respect to a plane formed by the rotation center axis of the welding torch 2 and the support shaft 3 of the robot, and an angle α (Fig. The angle formed by the irradiation center axis and the center axis of the image pickup system with the Z axis, that is, the rotation center axis of the support shaft 3 of the robot is θ (not shown), and the magnification of the image pickup system is shown. Let A be the position deviation vector Is given by

The image processing device 18 uses the position deviation vector component of this data with Y ′ = 0. Is calculated and sent to the robot controller 13 (step in FIG. 10).

The robot control device 13 performs coordinate conversion according to the equation (1) based on each joint angle information at the time of detection, and shift vector of the wire tip position of the welding torch 2 in the robot coordinate system. Then, the tip of the wire is moved to this position (step in FIG. 10).

FIG. 10 is a flowchart showing the operation of the robot at this time.

As shown in the flowchart, the robot performs the detection by the visual sensor 1 and the movement of the support shaft 3 of the robot as a series of operations until the position deviation vector becomes zero, that is, Until the teaching point 0 ', which is the reference point of the visual sensor 1, coincides with the groove position, this cycle of operation is repeated.

And Difference vector from the current position of the final welding torch 2 to the sensing start position Is calculated and used as the amount of deviation of the groove position (step in FIG. 10).

FIG. 11 shows the position deviation vector which is the detection vector of the visual sensor 1 by this repetitive operation. And welding torch 2 wire tip vector The figure shows how the value changes and converges to zero.

The subscripts 1, 2, 3, ... In O indicate the number of repetitive operations, and clarify the change of the vector that converges to zero.

After this detecting operation, the robot 12 has a welding path consisting of welding start and end points shown in FIGS. 6 (b) and (c).
That is, the start and end Titi lines of welding are Correction is made with the amount of deviation, and welding torch 2 is moved to the correction line to perform welding (Fig. 10 step).

By the above-described operation, even if the groove portions at the start of the welding line are displaced in the X'and Z'directions, respectively, and the Y'axis and the welding line are not aligned, the support shaft 3 which is the wrist of the robot. Difference vector indicating the groove position in the plane formed by the rotation center axis of the welding torch 2 and the axis of the welding torch 2. Can be detected.

As described above, according to this embodiment, since the groove position in the plane formed by the axis of the welding torch 2 and the rotation center axis of the robot support shaft 3 can be detected at the welding start point, the visual sensor 1 can be detected.
There is an effect that the detection position does not move back and forth in the direction of the welding line even if there is a posture in the detection of or the deviation of the workpiece 11 in the height direction.

Further, since the detection is repeated in the direction in which the data converges, the detection error can be evaluated, and the detection can be performed with high accuracy.

Further, since the above operation is performed at the retracted point, there is an effect that the detection can be performed without the collision of the wire tip of the welding torch 2 and the workpiece 11.

In addition, although the above-mentioned embodiment explained the groove position detection method at the welding line starting end of the welding robot system when performing welding, the present invention is not limited to only welding, and for example, sealing of automobiles, such as sealing. This method is also applicable to machining, has a teaching / reproducing function, and is a method that can be generally applied to detecting the machining groove position of a machining line by a robot equipped with a visual sensor.

[Effects of the Invention] As described above, according to the present invention, there is provided a method for detecting the groove position of the processing line starting end capable of detecting the groove position deviation of the processing line starting end without shifting the detection position in the processing line direction. You can submit.

[Brief description of drawings]

FIG. 1 is a side view of a robot supporting part of a welding robot according to an embodiment of the present invention, to which a visual sensor is attached, FIG. 2 is a front view of FIG. 1, and FIG. FIG. 4 is a schematic diagram showing the hardware configuration of the control system, FIG. 5 is an explanatory perspective view showing a welding path teaching method, and FIG. 6 is a reproduction operation. 7 is an explanatory perspective view showing the retracting operation, and FIG.
(A) is a perspective view, (b) is an enlarged view of the wire tip portion, FIG. 8 is an explanatory view showing a light cutting image detection screen, and FIG. 9 is a groove position of a welding start point and a welding torch. 10 is an explanatory perspective view of the moving position, FIG. 10 is a flowchart of the robot operation at the detection point, and FIG. 11 is an explanatory perspective view showing the progress of detection at the detection point and the progress of movement of the welding torch. 1 ... Vision sensor, 2 ... Welding torch, 3 ... Robot support axis, 6 ... Slit light source, 10 ... Observation optical system,
11 ... Workpiece member, 12 ... Robot, 13 ... Robot control device, 14 ... Teaching operation panel, 18 ... Image processing device, 19 ...
… Teaching box.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masamichi Tomita 502 Jinritsucho, Tsuchiura-shi, Ibaraki Prefecture, Ritsumeisho Co., Ltd. Mechanical Research Institute (72) Inventor Kyoichi Kawasaki 7-1-1 Higashi Narashino, Narashino, Chiba Co., Ltd. Hitachi Narashino Factory (72) Inventor Yasushi Shimura 7-1-1 Higashi Narashino, Narashino City, Chiba Prefecture Hitachi Keiyo Engineering Co., Ltd. (56) Reference JP-A-58-87603 (JP, A) JP-A-60- 37273 (JP, A)

Claims (1)

[Claims] 1. A robot having a teaching / reproducing function, a robot controller, and a visual sensor fixed to a support shaft of the robot for detecting a position of a groove at a starting end of a machining line.
A method for performing machining by correcting the positional deviation between the teaching position and the machining position by using the arithmetic function of the robot control device, which comprises a machining means that is inclined and fixed with respect to the axis of the support shaft of the robot. In the first step, a first step of calculating a retreat point retracted from the teaching position of the machining line start end in the axial direction of the machining means by a constant distance, a second step of moving the machining means tip to the retreat point, The third step of operating the visual sensor to detect the groove position at the machining start end, and the fourth step of calculating the position deviation vector of the groove portion detected in the third step with respect to the detection reference point of the visual sensor. A fifth step of calculating a position deviation vector component in a plane formed by the rotation center axis of the robot support shaft and the axis of the processing means among the position deviation vectors; and the fourth step. And a sixth step of moving the support axis of the robot in the direction of the position deviation vector obtained in step 4, the third step to the sixth step are sequentially performed until the position deviation vector in the fourth step becomes zero. A groove position detecting method for a machining line starting end, wherein the position deviation vector component obtained in the fifth step at the time when the position deviation vector becomes zero is repeatedly set as the deviation amount of the groove position.