JPS63251182A - Method of detecting position of bevel of working-line start end - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a method for detecting the groove position at the starting end of a processing line, and in particular, for example, when controlling the position of a welding robot, detecting the starting position of the processing line at the groove position to be processed. The present invention relates to a method for detecting the groove position of the starting end of a processed line, which is suitable for detecting positional deviation of the machined line.

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

This technology irradiates a linear beam of light, that is, slit light, in a direction perpendicular to the processing line direction, and generates a three-dimensional image of the groove from a light-cut image obtained by an imaging device that is integrally formed with the slit light source. The coordinate position was detected. Then, the starting and ending ends of the processing line are moved in parallel in the direction of the deviation vector between this detected position and the taught position, and the welding torch is moved so as to follow this processing line.

[Problems to be Solved by the Invention] The vision sensor according to the prior art described above can only detect the groove position within the plane irradiated with the slit light, and cannot detect the position of the groove at the time of detection or the height of the workpiece. No consideration was given to the fact that the irradiation position of the slit light moves back and forth in the direction of the processing line due to positional deviation in the direction, and there was a problem that the position of the starting end to be processed was shifted in the direction of the processing line.

The present invention was made in order to solve the problems of the prior art described above, and it is possible to
It is an object of the present invention to provide a method for detecting the groove position of the starting end of a working line by detecting a deviation in the groove position of the starting end of the working line.

[Means for Solving the Problems] In order to achieve the above object, the method for detecting the groove position at the starting end of a processed line according to the present invention includes a robot having a teaching/reproducing function, a robot control device, and a support for the robot. The robot controller comprises a visual sensor fixed to the shaft and configured to detect the positional deviation vector of the groove at the starting end of the processing line, and a processing means fixed at an angle with respect to the axis of the support shaft of the robot. Using the arithmetic control function, a retraction point is calculated that is retracted by a certain distance in the axial direction of the processing means from the teaching position of the starting end of the machining line, and a machining line with the point before retraction as the reference point is created with respect to this retraction point. The positional deviation vector of the groove at the starting end is detected by the visual sensor, and of this positional deviation vector, the positional deviation vector component in the plane formed by the rotational center axis of the support shaft of the robot and the axis of the processing means is detected. Using , a series of operations to move the robot's support shaft in the direction of this position deviation vector is repeated until the position deviation vector becomes zero, and the position of the robot's support shaft at the time when detection starts is determined. The difference vector from the position of the support shaft of the robot at the time when the positional deviation vector finally becomes zero is set as the amount of deviation of the groove position.

[Operation] According to the above method, the visual sensor detects the detected three-dimensional positional deviation vector of the groove at the starting end of the machining line within the plane formed by the rotation center axis of the robot's support shaft and the axis of the machining means. Since only the position deviation vector component of is sent to the robot control device, the support shaft of the robot moves only within the plane.

Therefore, the reference point of the visual sensor coincides with the plane when the positional deviation vector becomes zero.

This allows the present visual sensor to detect the groove position within the plane, so that the starting point of the machining line does not shift in the front-rear direction of the machining line.

[Embodiments] Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 11, taking a welding process as an example.

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

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

In FIGS. 1 and 2, 1 is a visual sensor that detects the groove position at the starting end of the welding line, 2 is a welding torch that is a processing means, and 3 is a robot support shaft that is a position control means for the welding torch 2. , 4 is a mounting jig for fixing the welding torch 2 to the support shaft 3 of the robot.

6 is a slit light source such as a semiconductor laser, which emits a slit-shaped light beam 5; 10 is a lens 7 and a mirror 8;
, and a solid-state image sensor 9. This observation optical system 10 measures a light section image formed on a workpiece 11, which is an object to be measured, when irradiated with a slit light source 6. It is something. 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 beam 5 and the central axis of the observation optical system 10 is configured to form a predetermined angle with the axis of the processing means, that is, the central axis of the welding torch 2. The line that equally divides the angle formed by the central axis of The reference point O' of the observation optical system 1° is placed at a point extended in the axial direction of the welding torch 2 by the amount of retraction (for example, lomn+) from the tip position ○ of the incorporated welding wire, and the slit beam 5 is also set at this point. It is adjusted so that it passes through the reference point ○'.

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.

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

A wire for welding is supplied from a wire reel 20 to a welding torch 2 via a conduit cable 22.

The wire is also connected to a welding machine 23 via a conduit cable 22, and shielding gas is supplied from a gas cylinder 25 to the welding machine 23 via a cable 24, and the shielding gas passes through the conduit cable 22 to a welding torch 23. be led to.

The robot 12 is a vertical multi-jointed robot having five degrees of freedom through rotary joints, and performs horizontal rotation, upper arm rotation, forearm rotation, wrist bending, and wrist twisting from the joints near the base.

Although not shown, the power of the motor is transmitted to each joint via a speed reducer. The optically sectioned image obtained by the visual sensor 1 is sent to the image processing device 18.
The position of the weld line in the screen and the position in the wrist coordinate system based on the position of the weld line are determined from the optically sectioned image.

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

In FIG. 4, the same symbols as in FIG. 3 indicate the same equipment and parts.

The robot control device 13 shown in FIG. 4 is connected to the robot 12 through a mechanical interface 26 and to the welding machine 23 through a welding machine interface 27. The computer-to-computer communication boat 28 in the robot control device 13 and the image processing device 18 are connected by a serial signal line. The slit light source 6 and the solid-state image sensor 9 in the visual sensor 1 are connected to the image processing device 18 by a signal cable 15 via a sensor tough knee connector 29, respectively.

ing.

Next, a method for detecting the positional deviation vector of the groove position at the welding start point using a welding robot equipped with such a visual sensor will be explained in accordance with FIGS. 1 to 4.
This will be explained with reference to FIGS. 5 to 11.

FIG. 5 is an explanatory perspective view showing a welding path teaching method;
The figure is an explanatory perspective view showing the reproduction operation, FIG. 7 is an explanatory view of the evacuation operation, (a) is a perspective view, (b) is an enlarged view of the tip of the wire, and FIG. 8 is an optically sectioned image. An explanatory diagram showing the detection screen,
Fig. 9 is an explanatory perspective view of the groove detection position at the welding start point and the moving position of the welding torch, Fig. 10 is a flowchart of the robot operation at the detection point, and Fig. 11 is the detection progress at the detection point. , is an explanatory perspective view showing the moving path of the i8 contact torch.

First, the teaching box 19 is used to teach the processing line, that is, the welding path in which the welding torch 2, which corresponds to the wrist of the robot 12, should operate. That is, after teaching the approach point shown in FIG. 5(,), at the welding start point shown in FIG. 5(b), the sensor for detection by the visual sensor 1 is turned ON;
Provides instructions on groove shape, welding torch shifting, etc. That is, various conditions such as the type of weld joint, detection of positional deviation of the groove, and correction of the welding path based on the detection are stored in advance in the storage unit (bubble memory) in the robot control device 13 using teach data ( For example, welding position.

position, welding speed, welding current, etc.).

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

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

The robot 12 moves along a previously taught path until it reaches the welding start point detected by the visual sensor 1, that is, by the sensor ○N.

At the point of sensor ○N, a retreat point shown in FIG. 6(a) is created based on the position data indicating that the sensor is ON, and the wire tip of the welding torch 2 is positioned at this point (Step 1 in FIG. 10). ).

A method for determining this evacuation point will be explained with reference to FIG.

In FIG. 7(b), ○' is a teaching point serving as a reference point of the observation system, and 0 is a retraction point where the wire tip is retracted in the axial direction of the welding torch 2 from the teaching point O'.

As shown in the figure, the position of the wire tip of the welding torch 2 after retraction, that is, the retraction point O, is the origin.

The direction of the rotation center axis of the robot's support shaft 3 passing through this origin is defined as the Z' axis, and the X' axis is set in a direction perpendicular to the 2' axis within a plane that includes this Z' axis and the axis of the welding torch 2. Coordinate system o-x'y' of welding torch 2 (wrist of robot 12)
Consider z'.

Assuming that the mounting angle of the welding torch 2 with respect to the coordinate system is 45', the retraction vector ρ' from the teaching point O' to the retraction point ○ is expressed as (4,= (-L/2 ．．
O, L/2).

This retraction vector a' is calculated from the robot coordinate system ox by the following formula based on the information on each joint angle of the robot at this time.
It can be converted into the evacuation vector B at yz.

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

n, =C1C2,4Cs　s,s.

ny = S 1C2J4 C5+ Cx S 5nz
=-82,4C3 θ-” Cx C234S s S z C5By
= 5lc234ss+clcsOz=s234ss d, =Cl52,4 d3=SiS234 d2=62,4 p, =C2< ds ・S 234+43 ・C23+
'? 2 ・cz) p = s 工 (d, ・S2, 400, ・C2, -Za, ・cz)pz=ds” C23
4-a3' Sza (22Sz here, Ci = cos D i (i = 1, -
, 5) S i =sinθi (i=1....
, 5) Cijk=cos (θi+θj+θk
)Sijk=sin (θi + Oj+θk)θ
1: Swivel joint rotation angle 0□: Humeral joint rotation angle θ,: Forearm joint rotation angle 042 Wrist bending joint rotation angle θ5: Wrist twist joint rotation angle C2: Upper arm length q,: Forearm length C5: Hand length be.

The robot 12 moves the welding torch 2 to the retreat point 0 calculated using equation (1) while maintaining its posture in the robot coordinate system at the time of teaching, and sends a detection command to the image processing device 18 along with information regarding the groove shape. .

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

Since the visual sensor 1 uses the teaching point O' shown in FIG. 7(b) as the reference point of the observation system, the positional deviation to the point S where the slit beam is irradiated is as shown in FIG. The vector ˜1 can be obtained (Step ① in Figure 10).

Here, the angles that the irradiation center axis of the slit beam 5 and the center axis of the optically sectioned image imaging system make with the plane formed by the welding 1/-chi 2 and the rotation center axis of the robot support shaft 3 are equal;
It is represented by an angle α (not shown), and the angle between the plane formed by the central axis of irradiation and the central axis of the imaging system and the Z axis, that is, the central axis of rotation of the support shaft 3 of the robot, is O (not shown), Assuming that the magnification of the imaging system is A, the positional deviation vector a' is given by the following equation.

The image processing device 18 calculates a positional deviation vector component a' with Y'=O out of this data, and sends it to the robot control device 13 (step 2 in FIG. 10).

The robot control device 13 performs the coordinate transformation of equation (1) based on the joint angle information at the time of detection, obtains a shift vector a4 of the wire tip position of the welding torch 2 in the robot coordinate system, and moves the wire tip to this position. (Step ■ in Figure 10).

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

As shown in the flowchart, the robot 1- 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, 4. This cycle of operations is repeated until '=o, in other words, until the teaching point 0', which is the reference point of the visual sensor 1, matches the groove position.

Then, calculate the difference vector A from the final current position of the welding torch 2 where θ=0 to the sensing (detection) start position, and use this as the deviation amount of the groove position (Step 1 in Figure 1o) ).

FIG. 11 illustrates how the positional deviation vector, which is the detection vector of the visual sensor 1, and/or the vector 4'1 of the wire tip of the welding torch 2 change and converge to zero due to this repeated operation. .

a:, tag', subscript 1.2' in o, 3...
・ indicates the number of repetitions, and clarifies the change in the vector that converges to zero.

After this detection operation, the robot 12 follows the welding path consisting of the welding start and end points shown in FIGS. 6(b) and 6(c),
That is, the start and end teach lines of welding are corrected by a shift amount of 6 times the difference vector, and the welding torch 2 is moved to the corrected line to perform welding (step 2 in FIG. 10).

Due to the above-mentioned operation, the groove at the starting end of the welding line becomes X'.

Even if there are deviations in the Z' force direction and the Y' axis and the welding line do not match, the rotation center axis of the support shaft 3, which is the wrist of the robot, and the axis of the welding torch 2 will remain in the plane. It becomes possible to detect a difference vector 6 indicating the groove position at .

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

Furthermore, since detection is performed repeatedly in the direction in which the data converges, it is possible to evaluate detection errors, and there is also the effect that detection can be performed with high accuracy.

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

The above-mentioned embodiment describes a method for detecting the groove position at the starting end of a weld line in a welding robot system when welding, but the present invention is applicable not only to welding but also to seals such as automobile seals. This method can also be applied to machining, etc., and can be applied generally to detecting the position of a machining groove on a machining line by a robot equipped with a teaching/reproduction function and 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 at the starting end of a processing line, which can detect a deviation in the groove position at the starting end of the processing line without shifting the detection position in the direction of the processing line. Can be submitted.

[Brief explanation of the drawing]

FIG. 1 is a side view of a robot support part equipped with a visual sensor of a welding robot according to an embodiment of the present invention, FIG. 2 is a front view of FIG. 1, and FIG. 3 is a welding robot equipped with a visual sensor. 4 is a schematic diagram showing the hardware configuration of the control system, FIG. 5 is an explanatory perspective view showing the welding path teaching method, and FIG. 6 is a diagram showing the regeneration operation. The explanatory perspective view shown in FIG. 7 is an explanatory diagram of the evacuation operation, and (a)
is a perspective view, (b) is an enlarged view of the wire tip, FIG. 8 is an explanatory diagram showing the optical cutting wire detection screen, and FIG. 9 is a welding DF.
An explanatory perspective view of the groove position at the J starting point and the moving position of the welding torch, Fig. 10 is a flowchart of the robot operation at the detection point, and Fig. 11 shows the progress of detection at the detection point and the progress of the movement of the welding torch. FIG. DESCRIPTION OF SYMBOLS 1... Visual sensor, 2... Welding torch, 3... Support shaft of robot, 6... Slit light source, 1o... Observation optical system, 11... Workpiece member, 12... - Robot, 13... Robot control device, 14... Teaching operation panel, 18... Image processing device, 19... Teaching box.

Claims (1)

[Claims] 1. A robot with teaching/reproduction functions, a robot control device, a visual sensor fixed to the support shaft of the robot to detect the positional deviation vector of the groove at the starting end of the processing line, and an axial center of the support shaft of the robot. The robot controller is equipped with a machining means that is fixed at an angle to the machining means, and uses the arithmetic control function of the robot control device to calculate and calculate a retraction point that is retracted by a certain distance in the axial direction of the machining means from the teaching position of the starting end of the machining line. The visual sensor detects the position deviation vector of the groove at the starting end of the machining line with respect to this retraction point using the point before retraction as the reference point, and among this position deviation vector, the rotation of the robot's support shaft is detected. Using the positional deviation vector component in the plane formed by the central axis and the axis of the processing means, a series of operations to move the support axis of the robot in the direction of this positional deviation vector are performed until the positional deviation vector becomes zero. Repeat this process and use the difference vector between the position of the robot's support shaft at the time detection starts and the robot support shaft at the time when the position deviation vector finally becomes zero as the amount of groove position deviation. A method for detecting a groove position at a starting end of a machining line, characterized in that: