JPS6021183A - Device for teaching direction of torch - Google Patents

Abstract

PURPOSE:To apply a command for turning a torch in the direction coinciding with the operator's sensation and to improve the efficiency of a teaching operation by operating the turning switches provided to a teaching panel. CONSTITUTION:The operator guides a weld point to a weld line by operating turning command switches 12x, 12y, 12z, 12alpha, 12beta and pushes a teaching switch, then Xp, Yp, Zp, l, m, n are stored in a storage device RAM. When a command switch 12alpha for horizontal turning and a command switch 12beta for vertical turning are operated, the signal goes to an input interface circuit I1 from which the signal is transmitted to a CPU. The CPU calculates directional cosines l, m, n, calculates angles theta1-theta5 of respective joints and drives motors M1-M5 until the angles coincide with the respective target values. The positional coordinates and the directional cosines are stored as teaching data in the storage device. When all the teaching operations are completed, the operator pushes a start button for reproduction. The teaching data is then fetched out of the storage device and the positional coordinates and directional cosines are calculated. The robot is positioned by the same method as in the stage of teaching.

Description

[Detailed Description of the Invention] The present invention provides a remote teaching type welding robot.
- The present invention relates to a torch direction teaching device, and more particularly to a torch direction teaching device that can give a command to turn the torch in a direction that matches the sense of an operator.

Figure 1 shows a conventional general welding robot.

In the case of such a robot, the swivel base 1 can be swiveled around a vertical axis 2 by a jM rotation motor (not shown) as shown by an arrow θ1.

A vertical arm 4 that can swing in a vertical plane about a fulcrum 3 is attached to the swivel table 11, and is rotated by an arrow θ2.
Perform a rocking motion without indicating.

At the tip of the mud vertical arm 4, there is an arrow 03 centered around the fulcrum 5.
A horizontal arm 6 is provided which can swing in the same vertical plane as the swing plane of the vertical arm 4, and the tip of the horizontal arm 6 has an axis 7 of the horizontal arm 6.
A wrist portion 9 that can pivot in the direction indicated by an arrow θ is disposed around a first axis 8 along the axis . (FIG. 1 shows the case where the first axis 8 coincides with the axis 7.) The wrist portion 9 also extends around the second axis 10 perpendicular to the first axis 8. The wrist portion 9 is swingable as shown by an arrow θ, and a welding torch 11 is attached to the tip of the wrist portion 9. This welding point of welding 1--chi 11 is represented by I).

The above-mentioned turning and swinging movements of θ1 to θ5 are all achieved by motors MI to M5, not shown in FIG. A resolver (such as a resolver) is attached to control the speed and position of each arm and wrist.

Now, suppose we use a position detector 208 to detect the angles θ1 to θ5.
The block diagram of a general control circuit for a welding robot as shown in Fig. 1 is as shown in Fig. 2. During teaching, the operator generally determines the position coordinates (Xr, Yr, Zr) of the welding point P in orthogonal coordinates centered on the robot and the direction of the welding torch by operating the teaching panel 12 for remote teaching. 0°, θ5
By specifying the value of , the robot R is driven and the welding point P is guided to an arbitrary position and the position data (X, , Y, , Z, , 0., .

θ, ) is stored.

In this way, the robot is intermittently taught the work trajectory in advance, and after storing it in the storage device 13 as a series of teaching data, the robot performs the playback work.

Re-η: Sometimes, the storage device 13 stored as described above
The teaching data (Xp, YP, z, θ.

θ5) in order and perform inverse transformation on this teaching data.
Il! The joint angle θ1 of each joint. θ2. θ3 is calculated, and these and θ1. Motor M1~ with the value of θ5 as the target value
M, and drive the Ibot according to the taught trajectory.

When teaching as described in item 1 above, in conventional welding robots, the position of the welding point P is commanded using x, y:z coordinate values in the orthogonal coordinate system -J- fixed to the robot, and the welding point is A method is generally used in which the direction of the torch 11 is commanded by a rotation angle given by θ and θ5.

In other words, in order to have the robot R perform a welding operation, the position coordinates (XP
, YP, ZP) and the angle θ1. which determines the attitude of the welding torch 11. It is necessary to give θ5, XP, Yr, Z
,,θ4. θ5 is directly input from the keyboard of the teaching panel 12, and by specifying the above xP, Yp + z, + θ4 and θ5, θ1 to θ3 are calculated by inverse coordinate transformation to be described later, and the thus obtained θ1 to θ
By performing servo control of each axis of the robot using the value of , as a target value, the robot is guided (recursively) to an arbitrary position and orientation.

On the other hand, in a welding robot, the posture of the welding torch 11, that is, the direction of the welding torch with respect to the welding line, has an important influence on the welding result, but in the conventional welding robot, the posture of the welding torch is determined by the joint angle θ4 as described above. It is determined by θ5. These angles θ4 and θ indicate the turning angles around the first axis 8 and the second axis 10 as shown in FIG. This method is based on the following and is unrelated to the operator's sense of direction, and requires considerable skill to accurately determine the attitude of the welding torch 11 by specifying such a turning direction.

That is, in actual welding work, the workpiece is usually set on the rotating table 14 as shown in FIG.
The teaching work is performed while guiding the welding torch 11 attached to the tip of the arm of the robot R along the workpiece by operating the robot. For example, in the case of fillet welding, the welding torch 11 is directed toward a point 16 on the welding line 18 of the workpiece 15, as shown in FIG. Welding is performed while moving the welding torch parallel to the welding line 18 while tilting the welding torch by a certain angle α with respect to the welding torch 18.
is the rotation angle of the welding torch 11 around the vertical axis perpendicular to the ground represented by the Z direction as shown in FIG. 5, and the angle β
Since the turning table 14 is a horizontal plane, generally the horizontal axis (
In the case of Fig. 5, it is expressed by a turning movement around the welding line 18), whereas θ and θ5 are expressed by the posture of the robot R itself, which is not directly related to these horizontal and vertical axes. The determined first axis 8 and the second axis 1 perpendicular to this
Therefore, the angles α and β in the direction in which the operator actually wants to rotate the welding 1-ch are determined by turning movements in the directions θ4 and θ5, which are not directly related to this. For the operator, setting these angles corresponding to the workpiece 15 facing in an arbitrary direction requires skill and is a laborious and tiring task. .

Further, the angle α that determines the attitude of the welding torch 11 as described above changes depending on the direction in which the workpiece 15 itself is placed and the type of welding such as fillet welding and butt welding, and For example, in the case of fillet welding as shown in the figure,
As shown in FIGS. 4(a) to (C), it is necessary to change it for each pass from the first to the third, and it is determined each time according to these welding conditions and the direction in which the workpiece 15 is placed. It is something. Therefore, the task of teaching these complicated tasks while specifying only the directions of θ and θ5, which are not directly related to the angles α and β, is extremely inefficient.

Therefore, the present invention provides a method for teaching the posture of the welding torch in the conventional welding robot as described above by specifying θ and θ5 in order to conveniently drive the robot example. The present invention provides a torch direction teaching device that can eliminate the difficulty of work, and its gist is that: a first turning movement about a first axis along the axis of a horizontal arm; A wrist portion having at least two degrees of freedom for second rotational movement about a second axis perpendicular to the first axis is attached to the tip of the horizontal arm, and a weld 1--ti is attached to the wrist portion. A torch direction teaching device for a remote teaching type welding robot, comprising: a teaching panel for remote teaching; a horizontal rotation command switch provided on the teaching panel for commanding rotation of a welding torch around a vertical axis; and the teaching panel. a vertical rotation command switch provided in the welding torch for commanding rotation about the horizontal axis of the welding torch;
a direction cosine calculation means for calculating a direction cosine indicating the attitude of the welding torch that changes in accordance with the rotation command signal from the horizontal direction rotation command switch and the vertical direction rotation command switch; Rotation angle calculation that calculates the rotation angle around the first axis and the second axis and the rotation angle of each joint to generate the first and second rotation movements of the wrist part from the cosine and the taught position coordinates of the welding point. The present invention provides a torch direction teaching device comprising: a drive device for rotating each joint according to the rotation angle about the first and second axes;

Next, embodiments embodying the present invention will be described with reference to the attached drawings to provide an understanding of the present invention.

Here, FIG. 6 is a functional block diagram showing the functions of a torch direction teaching device according to an embodiment of the present invention, FIG. 7 is a plan view showing an example of a teaching board that can be used in the same embodiment, and FIG. 9 is a flowchart showing the operating procedure of the same embodiment, and FIG. 9 is a block diagram showing an example of a control circuit that can be used in the same embodiment.

In FIG. 9, there is a teaching panel I2, a turning command switch 12, . 12χ, 12
．． ．． 12α and 12β, and each rotation command switch is physically composed of two types, one for the plus direction and one for the minus direction, and each rotation command switch is connected to the microcomputer 19 via the A/D converter 18a. It is connected to an input interface circuit 11 that constitutes the.

The microphone [I computer 19 can be a well-known one, includes a ROM for writing a control program, and a human interface circuit 1 according to the program written in the ROM. It performs arithmetic processing on the data while importing external data from the memory device or exchanging data with the temporary storage RAM, and outputs the processed data as necessary. Including the central processing unit CPU that outputs to external devices,
The temporary storage device RAM stores the position coordinates (XP, Y,.

Zr) and the direction cosine of the torch j2. m and n are stored. However, the direction cosine 6. θ4. which is determined by the inverse transformation described later by replacing m and 'n. θ5 may be stored.

Control circuits corresponding to the motors M1 to M5 that drive the five joints are connected to the output interface circuit 12, and since all of these five control circuits have the same configuration, there is no degree of freedom. A control circuit for the motor M for driving the shaft will be representatively explained.

The output interface circuit 2 includes a D/A converter 2 for generating an analog signal to be sent to the motor M1.
0X is connected, and the turning command signal such as 61 sent from the output interface circuit I2 is sent to this D/A converter 2.
The signal 0x is converted into an analog signal, passed through a comparator 21x, and amplified by an amplifier 22x, thereby driving the motor M1.

A swivel base 1 is attached to the motor M via a speed reducer (not shown), and the motor M turns according to the value of a turning command signal θ1, and its rotational speed is detected by a tacho generator TGI. The output of the generator TGI is fed back to the comparator 2-IX for speed feed hacking. Further, the rotational position of the motor M is detected by a pulse encoder I) IΣ connected to it,
The counter C connected to this pulse en τ node PI foil
1 is fed back to the human interface circuit 11,
The motor Ml is driven until the difference Δθ1 from the target value θI becomes 0.

Next, the teaching and reproducing operations performed using the control circuit and the arithmetic function of the microcomputer 19 will be described with reference to flowcharts 1 to 8 shown in FIG.

In the remote teaching type welding port ten soto according to the present invention, all teaching work is performed by the operator guiding the robot R to an arbitrary position by operating the rotation command switches 12X to 12β provided on the teaching panel 12. .

In order to guide the wrist part 9 of Roboso I-R to a predetermined position, the operator must: 12. ．． 12y, 12.12°, 12β
By operating the rotation command switch 12x to guide the welding point P to the welding line 18 shown in FIG. 5 and pressing the teaching switch at that position, outputs XP, YP from the rotation command switches 12x to 128 are obtained.

Zp'+ α, β are taken in (step a), subjected to conversion processing to be described later, and stored as x, in the temporary storage RAM.

Yp, Zp+ β, m, n are stored.

To guide the welding torch 11, the operator presses the horizontal rotation command switch 12α to rotate the welding torch around the vertical axis, that is, in the horizontal plane, and the horizontal rotation command switch 12α to rotate the welding torch in the vertical plane around the horizontal axis. This is done by operating the vertical direction turning command switch 12β that commands the angle signals α and β.

A turn in the α direction within the horizontal plane is 1M times around a vertical axis perpendicular to the ground centered on the operator, and a turn in the β direction is also around a horizontal axis centered on the operator. Since it is a swing, the direction of the swing is easy for the operator to grasp, and no skill is required for operation.

In this way, the operator controls the horizontal direction rotation command switch 12α.
and the vertical direction turning command switch 12β to move the desired angle in the α direction and β direction (this is specified by the time each switch is pressed, and the direction of the h1 turn is the positive switch or the negative switch). Activating each switch (selected arbitrarily by pressing the switch)
The signal passes through the Δ/D converter 18 (FIG. 9), reaches the input interface circuit f1, and is transmitted to the CPU.

When the CPU receives the horizontal direction rotation command signal (hereinafter referred to as the α signal for convenience) and the vertical direction rotation command signal (hereinafter referred to as the β signal for convenience), the CPU changes the attitude of the welding torch 11 as shown in equation (1). Direction cosine 1. , rrt, n (step b).

Then, in order to position the robot in the specified position and direction, perform inverse transformation on Xp, Yp, Zp, A, m, and n and calculate the angles θ1 to θ5 of each joint (Step C), thus obtained. Using the joint angles 01 to θ5 as target values, the motors M1 to M5 are driven until their rotational positions match the respective target values (step d).

When positioning is completed, the position coordinates (xr, Yp).

Z, ) and direction cosine (attitude data) (β, m, n) are stored in the storage device as teaching data. A1 (S As mentioned above, the data to be stored is the direction cosine (7!, m, n
) to determine the direction of welding 1. θ
5 may be memorized. The teaching work described above is performed at each teaching position intermittently.

The above inverse transformation is the direction cosine β, m, n, position coordinates XP, YP
, ZP into equation (2) to calculate θ1 and θ5, and then θ1. θ5. Substitute l into equation (3) to calculate 0, and then calculate θ9 from (4). This is to obtain θ3.

Here, Zq is the Z° force direction position coordinate of the rotation center Q of the welding torch 11 shown in FIG. 1, and the known XP, YP, ZP
, 12. m, n, θ1. θ is calculated by equation (5), and rl to r4 are the radius of rotation of each turning portion as shown in FIG. 1, rl is the radius of rotation of the vertical arm 4, r2 is the radius of rotation of the horizontal arm 6, r3 is the radius of rotation of the wrist portion 90, and r4 is the distance from the first axis 8 to the welding point P.

r'''-Xζ+Y;+';l When θ and ˜θ5 are thus obtained, the CPU outputs these signals to each motor via the output interface circuit I2 (step d).

To explain the above teaching drive procedure for the θ command, for example,
The command signal θ outputted from the output interface circuit I is converted into an analog signal by the D/A converter 20α, and then passed through the comparator 2Iα and amplified by the amplifier 22α to drive the motor M4.

The motor M4 rotates the wrist portion 9 in the direction of θ4 shown in FIG.
speed feedback control is performed. The rotational position of motor M4 is determined by pulse encoder PE connected to it.

ζ is detected by this pulse encoder PE.

The output of the counter C1 connected to is fed back to the input interface circuit 11, and the motor M is driven until the difference Δθ order from the target value θ4 becomes O.

When all the teaching work is completed, the playback work is started. When the playback start button is pressed, the teaching data is sequentially retrieved from the storage device and is processed using the known linear interpolation, 1-circular interpolation method, etc.
Position coordinates of interpolation points between teaching points (XPr, YP; ,
Zp: ) and direction cosine (j!i, mi, nl) force -h, θ'.~θshi is calculated by the same method as in the teaching described above, and the robot is positioned at that point.

In this way, the regeneration operation is performed sequentially along the weld line, and the positioning regeneration is continued continuously.

As described above, the present invention provides a first pivoting motion centered on a first axis along the axis of a horizontal arm, and a second pivoting motion centered on a second axis perpendicular to the first axis. In a remote teaching type welding robot 1--1 direction teaching device, a wrist portion having at least two degrees of freedom for rotational movement is attached to the tip of a horizontal arm, and a welding torch is guided to the wrist portion. - A teaching panel for teaching, a horizontal rotation command switch provided on the teaching panel for instructing the welding torch to rotate around the vertical axis, and a horizontal rotation command switch provided on the teaching panel for instructing the welding torch to rotate around the horizontal axis of the welding torch. The direction cosine indicating the attitude of the welding torch that changes in response to the vertical rotation command switch 7 which commands the rotation of the welding torch, the horizontal rotation command switch, and the rotation command signals from the vertical rotation command switch is calculated. The direction cosine calculating means calculates the first position of the wrist from the direction cosine of the welding torch indicated by -h and the position coordinates of the taught welding point.
and the first causing the second pivoting movement! a rotation angle calculating means for calculating a rotation angle around the first and second axes and a rotation angle of each joint; and a drive device for driving each joint to rotate in accordance with the rotation angle around the first and second axes. 1. Since this is a direction teaching device characterized by having the following features, when performing teaching work, the operator can issue a command to turn the welding torch in a direction that is easy for the operator to understand, and the teaching work can be performed easily. The efficiency of teaching is significantly improved, and the operator does not feel fatigued during teaching, allowing accurate teaching work to be performed quickly.

[Brief explanation of drawings]

Fig. 1 is a side view of a conventional general welding robot, Fig. 2 is a control circuit diagram of the conventional welding robot, and Fig. 3 is a perspective view showing the switch state of the conventional welding robot.
Fig. 4 is a side view of the welding 1-ch and I nok to explain the welding process, Fig. 5 is a perspective view to explain the operating angle of the welding 1-ch with respect to the workpiece, and Fig. 6 is the main part. A functional block diagram showing the functions of the I/- direction teaching device according to an embodiment of the invention, FIG. 7 is an iF plane view of teaching q)r that can be used in the embodiment, and FIG. 8 is a diagram showing the same implementation. FIG. 9 is a block diagram showing the control circuit of the same embodiment. (Explanation of No. 91) 1... Swivel base 2... Vertical axis - 4... Vertical arm 6... Horizontal arm 8... First
Axis core 10...Second axis core 11...l8 contact 1--chi
12...Teaching panel 13...Storage device 19...Microcomputer θ1 to θ,...Joint angle P...Welding point M1 to M5...Motor R...Robot 1, . 12... Input/output interface circuit TG...
・Tacho generator PE...Pulse encoder C...Counter. Applicant Kobe Steel Co., Ltd. Agent Patent Attorney Takeo Honjo Figure 7-418- Figure 8

Claims (1)

[Scope of Claims] At least a first rotational movement centered on a first axis along the axis of the horizontal arm, and a second rotational movement centered on a second axis perpendicular to the first axis. In a remote teaching type welding robot/nod torch direction teaching device in which a wrist portion having two degrees of freedom is attached to the tip of a horizontal arm and a welding torch is attached to the wrist portion, (1) a teaching panel for remote teaching; (2) a horizontal rotation command switch, which is provided on the teaching panel and instructs the welding torch to rotate around the vertical axis; (4) Calculate the direction cosine indicating the attitude of the welding torch that changes according to the rotation command signals from the horizontal rotation command switch and the vertical rotation command switch. a direction cosine calculation means; (5) a means for calculating a first axis and a second axis that causes first and second rotational movements of the wrist portion from the direction cosine of the welding torch and the taught position coordinates of the welding point; (6) a drive device that rotates and drives each joint according to the rotation angle about the first and second axes; A torch direction teaching device characterized by: