JPH0233164B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to a welding robot or a traveling trolley type robot, which includes a rotating body that can make one or two rotations relative to a main body, and detects the rotational position of the rotating body using an incremental encoder. The present invention relates to an origin positioning control device for the rotating body in a profile welding device or the like.

BACKGROUND ART Conventionally, welding robots are well known in which a rotating body is pivotably supported on a main body so as to be rotatable within one rotation, and the rotating position of the rotating body is detected using an incremental encoder. In this case, in order to determine the origin of the rotating body with respect to the main body, if one origin position detector is provided between the main body and the rotating body, the rotating body can be rotated from one end to the other. Even if the sensor is moved, the detector outputs an output only once, so the origin position can be easily determined based on the output signal. However, when the rotating body rotates one or two times with respect to the main body, the detector outputs twice while the rotating body rotates from one end to the other, and which output is It becomes unclear whether or not to perform home positioning based on the signal.

The present invention has been made in view of the above-mentioned circumstances, and provides a simple control device that can reliably position the origin of the rotating body with respect to the main body even when the rotating body can make one or two rotations with respect to the main body. The present invention is intended to be provided with a simple configuration, and examples will be described in detail below.

In this embodiment, a rotating body is vertically supported on a main body having a steering mechanism, that is, a traveling truck, so as to be able to rotate once or twice, and a sensor and a welding torch are indirectly supported on the rotating body. Although the present invention will be described as a control device for determining the origin position (start position) of the rotating body relative to the main body in a traveling trolley type fillet profile welding device, the present invention is not limited to this embodiment.

W ₁ and W ₂ are workpieces, where W ₁ is a horizontal workpiece and W ₂ is a vertical workpiece. and both works
W ₁ and W ₂ are mutually positioned and tack welded in advance as shown in FIG. WL is both workpieces
This is a weld line formed by W ₁ and W ₂ .

Reference numeral 1 denotes a main body of a traveling trolley (having a square planar shape in the embodiment), on which a total of four wheels 2 are mounted. All wheels 2 are configured to be driven in the same direction by an electric motor _M1 attached to the bottom of the truck 1 via a power transmission mechanism 3 consisting of a chain 3a, sprockets 3b, 3c, and bevel gears 3d, 3e. ing. Although _E1 is not shown in detail, it is an encoder for detecting the travel distance connected to the wheel 2. S1 is a servo system including an electric motor _M1 and an encoder _E1 .

Reference numeral 4 denotes a steering mechanism, which is configured to be able to simultaneously steer all wheels 2 in the same direction and at the same angle via a chain 4a and sprockets _4b , 4c by an electric motor M2 attached to the bottom of the truck 1.
E ₂ is a steering angle detection encoder of the mechanism 4, although its details are not shown. S2 is a servo system including electric motor _M2 and encoder _E2 .

5 is vertically supported 5a at the upper center of the trolley 1,
In the example, ₂
It is a rotating body that rotates slightly (approximately 700 degrees). E ₃
Although not shown in detail, is an encoder for detecting the rotation angle of the rotating body 5. S3 is a servo system including electric motor _M3 and encoder _E3 .

6 is supported by the rotating body 5, and is driven by an electric motor _M4 ,
It is a movable body that can be moved in the horizontal direction via a known ball screw type transmission mechanism 7. _E4 is an encoder for detecting the position of the moving body 6. S4 is a servo system including electric motor _M4 and encoder _E4 .

Reference numeral 8 denotes a tilting member which is connected to the moving body 6 by a horizontal shaft 8a in a direction perpendicular to the moving direction thereof, and can be moved up and down by an electric motor _M5 . _E5 is an encoder for detecting the tilt angle of the member 8. S5 is a servo system including electric motor _M5 and encoder _E5 .

Reference numeral 9 denotes a mechanism which is vertically supported by the lower part of the tilting member 8, and whose tip output member is horizontally rotated around an imaginary point. In the embodiment, it is a parallel link mechanism consisting of two sets of parallelogram links. be. Mechanism 9
The links 9a and 9b are vertically supported 9c and 9d at the bottom of the member 8, and a lever 9 is provided at the tip of the link 9a.
A pair of parallelogram links formed by connecting a link 9f with a protruding point 9e, and connecting the tip of the lever 9f' and the tip of the link 9b 9g, and a lever 9a that projects from the tip of the link 9a. It consists of a pair of parallelogram links in which a link 9h is connected to the tip 9i, and links 9j are connected 9k and 9l between the tips of the links 9f and 9h. M ₆ is link 9
This is an electric motor that rotates a. Note that the distal end output member of the mechanism 9, that is, the distal end link 9j is configured as a holding member for the welding torch T. _E6 is an encoder for detecting the angle of the torch T with respect to the welding line WL by the mechanism 9. S6 is a servo system including electric motor _M6 and encoder _E6 .

SH is a profile sensor in the left-right direction, that is, in the Y direction, supported at the tip of the holding member 9j, and in the embodiment, the workpiece W ₂ is horizontally attached to the tip of the holding member 9j and is biased to protrude by a bullet (not shown).
1, and a protrusion position detector (differential transformer in the embodiment) _TR1 of the rod 10 to which the holding member 9j is attached.

In addition, at the protruding position of the rod 10 at the preset reference output value of the transformer TR ₁ , the shafts 9c,
The distance between the shafts 9e and 9k is equal to the distance between the shafts 9k and the tips of the rods 10, and the distance between the shafts 9e and 9k is
9c and the distance between the tips of the rods 10 are set to be equal.

SV is the vertical direction (Z
In the embodiment, the sensor is attached to the horizontal surface tracing rod 11 of the workpiece _W1 , which is horizontally attached to the lower part of the holding member 9a and urged downward by a bullet (not shown), and to the holding member 9j. and a protrusion position detector (actuating transformer in the embodiment) _TR2 of the rod 11.

Note that the tilting member 8 is set to be horizontal at the protruding position of the rod 11 at a preset reference output value of the transformer _TR2 .

The attachment position of the torch T to the holding member 9j is determined at the welding point of the torch T at the protruding position of the rod 10 at the reference output value of _{the transformer TR 1 and} at the protruding position of the rod 11 at the reference output value of the transformer TR 2. The position P is set below the tip of the rod 10 and on a horizontal plane passing through the tip of the rod 11.

Therefore, the position P of the welding point of the torch T is configured so as not to be displaced regardless of the rocking motion of the mechanism 9.

SS is a total of eight limit switches, two of which are protruded from each side wall of the truck 1, and can detect a collision of the truck 1 with the workpiece _W2 .

LR is a first detection device that detects whether the rotating body 5 is in a positive or negative rotation range with respect to a preset intermediate rotation position. This example device
LR is a protrusion 12 provided on the vertical shaft 5a of the rotating body 5.
is vertically supported by the cart 1, and its tip is connected to the protrusion 12 at the engagement point (in the embodiment, the rollers 14, 1
5), and is biased by a snap action by a spring (tension spring) 16, and whose rotation angle is limited by stoppers 17 and 18 fixed to the trolley 1; The sensor SW ₁ (in the embodiment, a normally open limit switch) detects the rotational position of the effecting body 13 due to the biasing of the snap action. Note that the switch SW ₁ can be turned ON and OFF by an end 13b of the effecting body 13 on the opposite side from the rollers 14 and 15.

HP is a second detection device that detects a specific rotational position of the rotating body 5 with respect to the cart 1. This embodiment device HP is composed of a protrusion 19 provided on the vertical shaft 5a and a detector SW ₂ (a normally open limit switch in this embodiment) which is switched on and off by the protrusion 19.

C is a control unit mainly composed of a computer including a central processing unit CPU and a memory MEM. This control section C includes each servo system S1 to S6, a welding power source
WS, transformer TR ₁ , TR ₂ , switch SW ₁ , SW ₂
etc. are connected via bus line B.

The control unit C includes (a) a first means A 1 for rotating the rotating body 5 in a direction in which the output signal can change according to the output signal from the switch SW ₁ ; and ( _b )
The said rotation in this means _A1 causes the switch to
When the output signal from SW ₁ changes, rotating body 5
and (c) the rotation of this means A ₂ causes _the switch to
When the output signal from SW ₂ changes (changes from OFF, i.e., signal "0" to ON, i.e., signal "1" in the example), the rotating body 5 is moved in either positive or negative direction (in the example, in the positive direction). and (iv) _the third means A ₃ which _is intended to be rotated to and a fourth means _A4 for stopping the rotating body 5 when the rotating body 5 changes to (changes to).

Further, the operation of this embodiment will be explained based on the flowchart of FIG. 7 and with reference to the signal diagram of FIG. 6.

First, turn on the power to the profile welding device and turn on the origin positioning switch (not shown). Then, all the components are at the preset origin position, that is, the steering angle of the wheels 2 is at a position where all wheels 2 are in the front-rear direction (X direction), and the rotating body 5 is set at a position where the moving direction of the moving body 6 is in the left-right direction (X direction). Furthermore, the movable body 6 is placed at the position where the reference output value of the transformer TR ₁ is obtained, and the member 8 is placed at the position where the reference output value of the transformer TR 1 is obtained.
The mechanism 9 is positioned at the position where the reference output value of TR ₂ is obtained, and furthermore, at the position shown in FIG. 3.

The origin positioning of the rotating body 5 will be described in detail below.

First, in step _ST1 , a determination is made as to whether ``this is the first home positioning after power-on''.

As a result, if it is not the first time, as in step ST ₂ , _the rotating body 5 is initially moved at high speed (approximately
13 degrees/second), and when the value is near "0", a command is output to the electric motor _M3 to rotate at a low speed (approximately 1 degree/second in the embodiment).

Also, if the judgment result of step ST ₁ is the first time,
As in step _ST3 , it is determined whether the output signal of the switch _SW1 is ON, that is, "1", or OFF, that is, "0".

As a result, the protrusions 12 and 19 are now at the positions 12 and 19 shown by solid lines in FIG. If it is in the position, the output signal of the switch SW ₁ is "0", which means that the rotational position of the rotating body 5 with respect to the cart 1 is in the negative direction rotation region. Therefore, as in step ST ₄ , a command is output to the electric motor M ₃ to rotate the rotating body 5 in the positive direction at high speed (approximately 13 degrees/second), and as in step ST ₅ , the switch SW ₁ is output. The rotating body 5 is rotated until the output signal changes to "1".

Conversely, if the operating body 13 is in the rotating position indicated by _{the two-} dot chain line in FIG. Therefore, the rotational position of the rotational body 5 with respect to the cart 1 is in the forward rotational region. Therefore, as in step _ST6 , a command is output to the electric motor _M3 to rotate the rotating body 5 in the negative direction at the high speed, and in step ST6,
Like ST ₇ , the output signal of switch SW ₁ is “0”
The rotating body 5 is rotated until the change occurs.

Note that the aforementioned steps ST ₃ , ST ₄ and ST ₆ constitute the first means A ₁ .

If the output signal of the switch SW ₁ changes in step ST ₅ or ST ₇ , the rotating body 5 is rotated in the negative direction at a medium speed (approximately 6 degrees/second in the embodiment) as in step ST ₈ . Electric motor M ₃ to make
command is output, and as in step ST ₉ ,
The rotating body 5 is rotated until the output signal of the switch SW ₂ changes to "1".

Note that the aforementioned steps ST ₅ , ST ₇ and ST ₈ constitute the second means A ₂ .

Then, in step _ST9 , if the output signal of the switch SW ₂ changes to "1", that is, if the protrusion 19 switches the switch SW ₂ to ON,
As in step ST ₁₀ , the electric motor is used to rotate the rotating body 5 in the positive direction at a low speed (approximately 1 degree/second).
A command is output to _M3 , and as in step _ST11 , the rotating body 5 is rotated until the output signal of the switch _SW2 changes to the original "0".

Note that the aforementioned steps _ST9 and _ST10 constitute the third means _A3 .

Then, in step ST ₁₁ , switch SW ₂
If the output signal changes to “0”, step
As in ST ₁₂ , a command is output to the electric motor M ₃ to stop the rotating body 5. At this time, each protrusion 12,
19 is located at the two-dot chain lines 12' and 19' in FIG. 4, and this position is the origin position (start position) HP ₀ of the rotating body 5.

Note that the aforementioned steps _ST11 and _ST12 constitute the fourth means _A4 .

And like step ST ₁₃ , encoder E ₃
A command is output to set the value of the counter to "0".

In this way, the origin positioning of the rotating body 5 with respect to the cart 1 is performed, and the rotating body 5 is positioned at a position where the moving direction of the moving body 6 is in the Y direction.

When the origin positioning is completed, the cart 1 is mounted on the workpiece _W1 , and the position P of the welding point of the torch T is adjusted so that the moving direction of the moving body 6 is almost perpendicular to the welding line WL. Set each as shown in Figure 1 so that they match the welding line WL.

Then, when the start switch (not shown) is turned on, the power source WS is turned on, and the truck 1 moves forward at a preset speed (in the X direction in Figure 1,
and left direction).

At this time, the output value from the transformer TR ₁ of the sensor SH is compared with a constant value, and the position of the moving body 6 is controlled so that the difference becomes zero, and the output value from the transformer TR ₂ of the sensor SV is also compared with the constant value. and the position of the inclined member 8 is controlled so that the difference becomes zero,
The position P of the welding point of the torch T is always aligned with the welding line WL. Although not described in detail, the direction of the welding line WL is always calculated based on the positional information of the welding point at regular intervals even if the welding line WL has a curve in the middle, and the direction of the welding line WL is always calculated from the position information of the welding point at a fixed time interval. The posture with respect to the line WL is controlled to be always constant, and the moving position of the moving body 6 is almost constant, that is, the carriage 1
The steering angle of the wheel 2 is controlled so that the distance between the welding line WL and the welding line WL is approximately constant, and the rotational speed of the wheel 2 is also controlled so that the welding speed is constant.

If the workpieces W ₁ and W 2 are welded such that the welding line WL is bent at 90 degrees in the middle, the cart 1 will eventually collide with the workpiece W ₂ as shown by the solid line in FIG _. 8. At this time, the two switches SS protruding from the front side of the truck 1 output signals, which then control the rotation direction of the wheels 2, the steering angle of the wheels 2, and the rotating body 5 based on a sequential program set in advance. The rotation angle and other details are controlled, and the bending points are welded as shown below.

First of all, the rotating body 5 has a torch T shown in Fig. 8 A double dot chain line.
The welding line WL is welded while being rotated to the right by a certain angle until reaching the T′ position. Next, the welding is stopped and the torch T is retracted to the position indicated by the solid line in Figure 8B. This retracted position is the same as the origin position of the moving body 6 described above.
Next, after the trolley 1 is retreated to the position indicated by the two-dot chain line 1' in FIG. After the trolley 1 advances to the solid line position in Figure 8C, that is, the position where the tip of the sensor SH contacts the workpiece _W2 , the wheels 2 are steered 90 degrees to the left, and the trolley 1 moves to the position indicated by the two-dot chain line 1' in Figure 8C. It travels to the left until it collides with the workpiece W ₂ (the collision position is detected by the switch SS).Next, the rotating body 5 is rotated to the left by a certain angle until the torch T reaches the position indicated by the solid line in FIG. Welding is then performed while rotating the rotary body 5 to the right by a certain angle until the torch T reaches the position shown by the two-dot chain line T' in FIG.

In this way, the weld line WL near the bending point
is welded, and welding of the welding line WL to the right from the position of the two-dot chain line T' in FIG.

Note that even if the wheels 2 are steered at the bending point of the weld line WL, the attitude of the truck 1 does not change because all the wheels 2 are steered in the same direction and at the same angle. Therefore, the rotating body 5 rotates 90 degrees to the right with respect to the cart 1 each time it passes the bending point. Therefore, there are a large number of bent welding lines as described above, and when welding them one after another, each time welding for one bent welding line is completed, because there is a limit to the rotation angle of the rotating body 5. The origin positioning must be carried out and each component of this welding equipment must be returned to the starting position. However, if this is not the first home positioning after the power is turned on, the contents of step ST ₂ will be executed, so the time required for home positioning will be the same as the first time step ST ₃ .
~ Compared to the case of ST ₁₃ , it is much shorter.

The above description is an example, and for example, the projections 12,1
For example, a light emitting diode or a permanent magnet may be used instead of 9, and a phototransistor or a reed switch may be used instead of the limit switches SW ₁ and SW ₂ . Further, the protrusions 12 and 19 may be provided on the trolley 1 side, and the other components of the detection devices LR and HP may be provided on the rotating body 5 side. Further, the third means A ₃ is the switch SW ₂
The rotating body 5 may be rotated in the negative direction when the output signal changes. Furthermore, the "1" part in the signal in FIG.
If the origin position HP ₀ is located in the positive rotation area excluding the negative rotation area, the second means A ₂ is configured to rotate when the output signal of the switch SW ₁ changes. What is necessary is to rotate the moving body 5 in the forward direction. Other sensors SH and SV may be non-contact type such as optical or electromagnetic type, or so-called arc sensors.In addition, in step _ST2 , as the value of encoder _E3 approaches "0", It goes without saying that the technical scope of the present invention also includes the replacement of each structure with equivalents, such as rotating the moving body 5 sequentially through three speed changes from high speed to medium speed to low speed.

As described above, this invention has a main body 1 of a rotating body 5.
(for example, the position indicated by the two-dot chain line in Figure 4, one position in each positive and negative rotation area)
In addition to the device HP that detects the position of the rotating body 5, there is also a device LR that detects whether the rotating body 5 is in a positive or negative rotation range with respect to a preset intermediate rotation position. The rotation direction of the rotating body 5 is controlled according to the output signal of SW ₁ , and the detector SW ₁ ,
Since the rotating direction of the rotating body 5 is controlled according to the change in the output signal of SW ₂ , even when the rotating body 5 rotates 1 to 2 times with respect to the main body 1, that is, the rotating body 5 rotates from one end to the other. Detection device while rotating to the end
Even if the HP applies the signal twice, the origin position of the rotating body 5 relative to the main body 1 can be accurately and reliably determined.

[Brief explanation of drawings]

Each of the figures shows an embodiment of the present invention.
The figure is an overall perspective view of the traveling truck type fillet profile welding device, Figure 2 is a bottom view of the main body, that is, the traveling truck, Figure 3 is a plan view of the vicinity of the torch holding member, and Figure 4 is the first and second detection devices. FIG. 5 is a block diagram of the control section, FIG. 6 is an output signal diagram of the first and second detectors, FIG. 7 is a flowchart, and FIG.
The figure is an action explanatory diagram. In the figure, 1... main body (traveling trolley), 5...
Rotating body, 5a...axis, C...control unit, LR...first detection device, SW ₁ ...first detector, HP...second
Detection device, HP ₀ ... Origin position, SW ₂ ... Second detector, A ₁ ... First means, A ₂ ... Second means, A ₃ ...
Third means, A ₄ ...Fourth means, 12...Protrusion, 1
3... Acting body, 13a... Shaft, 14, 15... Engaging portion, 16... Spring, 17, 18... Stopper, 19... Protrusion.

Claims (1)

[Scope of Claims] 1. A main body, which is pivotally supported by the main body, and 2.
a rotating body capable of rotating less than one rotation; a first detection device for detecting whether the rotating body is in a positive or negative rotation region with respect to a preset intermediate rotation position; A second detection device that detects a specific rotational position with respect to the main body, and a control section that inputs output signals from the first and second detection devices, and the control section includes a second detection device that detects a specific rotational position with respect to the main body. a first means for rotating the rotating body in a direction in which the output signal can change based on the output signal;
The rotation in this first means causes the first
a second means for rotating the rotary body in either a positive or negative direction when the output signal from the detection device changes; a third means for rotating the rotating body in either a positive or negative direction when the output signal changes; and the rotation in the third means causes the output signal from the second detection device to be and fourth means for stopping the rotating body when the output signal changes to the original output signal. 2. The first detection device is pivotally supported by a protrusion provided on either the main body or the rotating body and the other rotating body or the main body, and has its tip formed as an engagement point with the protrusion. It also includes an effecting body whose rotational angle is limited by a stopper and a snap action biased by a spring, and a detector for detecting the rotational position of this effecting body by the snap action. , an origin positioning control device according to claim 1. 3. The first means sets the rotating speed of the rotating body to a high speed, the second means sets the rotating speed of the rotating body to a medium speed, and the third means sets the rotating speed of the rotating body to a high speed. The origin positioning control device according to claim 1, wherein the origin positioning control device has a low speed.