JPS643662Y2 - - Google Patents

Description

[Detailed explanation of the idea]

This invention relates to a control device for an industrial robot that is capable of changing the speed of a controlled axis in stages. For example, even if an 8-bit CPU is used to control the speed of a controlled axis, the drive circuit for each controlled axis may only be able to change the speed by, for example, 5 bits. In other words, the speed value can only be set in 32 steps. In this case, the speed values are usually set to a maximum speed value, a minimum speed value, and each value obtained by dividing the distance between the two speed values into 31 equal parts. However, in some cases, an intermediate value between the set adjacent speed values may also be required. In this case, it would be possible to increase the number of bits of the CPU, but this would be uneconomical. This idea was created in view of the above-mentioned circumstances, and is a control system that allows the desired speed value to be approximately obtained even when the desired speed value cannot be set because a sufficient number of bits are not available for changing the speed. The present invention aims to provide an apparatus, and examples thereof will be described in detail below. In this embodiment, the industrial robot is equipped with a torch support member on a traveling trolley, controls the position of the support member via a control device based on the output of a welding line tracing sensor, and travels to trace a welding line and perform welding. Although this embodiment will be described as a trolley-type profile welding robot, the invention is not limited to this embodiment. W ₁ and W ₂ are workpieces, respectively, where W ₁ is a horizontal workpiece and W ₂ is a vertical workpiece. Both works
W ₁ and W ₂ are mutually positioned and tack welded in advance as shown in FIG. WL, WL ₁ ~
WL ₄ is a processing line (horizontal fillet weld line) formed by both workpieces W ₁ and W ₂ and bent at 90 degrees. Reference numeral 1 denotes a traveling trolley whose planar shape is approximately quadrilateral (approximately square in the embodiment), and a total of four wheels 2 are mounted thereon. 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 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 and 4c using 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,
It is a rotating body rotated by electric motor _M3 . _E3 is
Although not shown in detail, it 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 . 5b is
This is a handle fixed to the upper part of the rotating body 5. 6 is a movable body supported by the rotating body 5 and movable in the horizontal direction by an electric motor _M4 . _E4 is an encoder for detecting the position of the moving body 6. S4 is
This is a servo system including electric motor _M4 and encoder _E4 . 7 is a tilting member supported by the movable body 6 and tiltable up and down by an electric motor _M5 . _E5 is an encoder for detecting the tilt angle of the member 7. S5 is a servo system including electric motor _M5 and encoder _E5 . Reference numeral 8 denotes a welding torch support member which is supported by member 7 and is rotated approximately horizontally about a shaft 8a by an electric motor _M6 . _E6 is an encoder for detecting the rotation angle of the member 8. S6 is a servo system including an electric motor _M6 and an encoder _E6 . SH is supported by the member 8, and is a horizontal direction tracing sensor (contact type in the embodiment) for the welding line WL;
Contactor 9 urged to protrude by a spring (not shown)
and a differential transformer TR ₁ connected to this contactor 9.
including. Note that the sensor SH is set so that the shaft 8a passes through the tip of the contact 9 at the protruding position of the contact 9 at a preset reference output value. Furthermore, the protrusion of the contactor 9 is limited by a stopper (not shown). SV is supported by the member 7 and is a horizontal direction tracing sensor (contact type in the embodiment) for the welding line WL;
Contactor 10 urged to protrude by a spring (not shown)
and a differential transformer connected to this contactor 10.
Including TR ₂ . Note that the sensor SV is set so that the member 7 is in a horizontal position at the protruding position of the contactor 10 at a preset reference output value. T is an end effector (welding torch) attached to the member 8. The mounting position of the torch T is such that at the protruding positions of the contacts 9 and 10 at the reference output values of the sensors SH and SV, the welding point P of the torch T is below the tip of the contact 9 and the contact 1
It is set to be located on a horizontal plane passing through the 0 tip. 11 is a conduit cable including a signal cable, a power cable, a power supply cable to the torch T, and the like. There are two SWs on each side wall of the trolley 1 (SW ₁
and SW ₂ ), a total of eight vertical workpiece W ₂ detection sensors (limit switches in the embodiment) are installed protrudingly. The traveling trolley type profiling welding robot R is composed of the above SWs 1 to SW. C is a control device mainly composed of a computer including an 8-bit CPU as a central processing unit and a memory MEM. The control device C includes each servo system S1.
~S6, operation panel REM, welding power source WS, transformer
TR ₁ , TR ₂ and switches SW ₁ and SW ₂ are connected via a bus line R. The control device C is capable of changing the speed of the controlled axes (the running axis of the truck 1 and the rotating axis of the rotating body 5) of the robot R of this embodiment in steps. In this embodiment, the number of bits for changing the speed in the servo systems S1 and S3 is 5, and the speed of the controlled axis is preset in 32 steps. Moreover, the control device C selects at least two types of set speed values from the 32 stages (in the embodiment, two types of speed values adjacent to each other are selected).
However, means F is included for sequentially and repeatedly outputting each of these selected speed values for a predetermined period of time. For example, when the controlled axis is the rotating body 5, the angular velocity value is from 0 degrees/second to 12.4 degrees/second at intervals of 0.4 degrees/second.
Angular velocity values are preset in 32 steps. Note that the same applies to the setting of the rotational speed of the wheels 2, so a detailed description thereof will not be given. The means F for the rotating body 5 is such that the high angular velocity value V _h and its execution time t ₁ and the low angular velocity value V _l and its execution time T ₂ are set in advance in a table according to the leg length, as shown in Table 1, for example. is stored in the memory MEM, and the value V _h
Execution of the value V _l for T ₁ hour and execution of the value V l for T ₂ hours are performed alternately.

[Table] Further, the operation of this embodiment will be explained based on the flowchart of FIG. 5 with reference to FIG. 4. First, the operator turns on the power switch and home positioning switch (not shown) on the operation panel REM.
Make it. At this time, the steering angle of the wheels 2 is such that all the wheels 2 are in the front-rear direction (the X direction in FIG. Furthermore, the moving body 6 is located at a position in the Y direction (in FIG. 1), and the transformer TR ₁
Further, the member 7 is placed at a position where the output value of the transformer TR 2 matches a preset reference output value, and furthermore, the member 8 is placed at a position where the output value of the transformer TR ₂ matches a preset reference output value. Direction (approximately the weld line)
Each torch is positioned at a position where the torch angle relative to the WL direction is optimal. Next, the operator operates a leg length selection switch (not shown) on the operation panel REM. Then, the operator holds the handle 5b and places the trolley ₁ on the workpiece _W1 as shown in FIG. , SV contacts the workpieces W ₂ and W ₁ , respectively. At this time, when welding the welding lines WL ₁ to _{WL 4} of the rectangle-shaped plane continuously on all four sides, the trolley 1 is set at the middle position of the welding line WL ₁ as the starting position, as shown by the solid line in Figure 1. Position. Therefore, when the start switch (not shown) on the operation panel REM is turned on, a command is output to turn on the power source WS (step ST ₁ ), and the electric motor is activated to move the trolley 1 forward at a welding speed corresponding to the selected leg length. A command is output to _M1 . (Step ST ₂ ). Moreover, counting by encoder E ₁ is started (step
ST ₃ ), further horizontal direction tracing control of the moving body 6 by the sensor SH, and member 7 by the sensor SV.
vertical tracing control is also started (step
_ST4 ). Furthermore, it is also set to (i=1) (step ST ₅ ). Note that i is a step described later.
Indicates the number of times ST ₆ to ST ₅₇ are executed. Therefore, in tracing control using sensor SH,
The output value from the transformer TR ₁ and the reference value are compared by the CPU, and the moving body 6 moves the workpiece W ₂ according to the difference.
Welding line of torch T, remote from or close to
The horizontal position with respect to WL ₁ is controlled, and in the case of tracing control by sensor SV, the transformer
The output value from TR ₂ and the reference value are compared by the CPU,
Depending on the difference, the member 7 moves away from or approaches the workpiece _W1 , the vertical position of the torch T with respect to the welding line _WL1 is controlled, and the welding line _WL1 is welded in a profile manner. Although not described in detail, during the above tracing, the position information of the welding point is collected at fixed intervals (for example, 0.1 seconds).
The direction of the welding line WL ₁ is calculated sequentially from the current position information and the previous position information.
As a result, the member ₈ is
The torch angle can be controlled by rotating around the axis 8a, or the wheels 2 can be steered so that the distance between the truck 1 and the welding line WL ₁ is approximately constant.
Furthermore, the wheels 2
The rotation speed of is also controlled. Then, by the above-mentioned profile welding, the bogie 1 was finally
The front end of the
It will collide with W ₂ . This collision is determined whether switch SW ₁ is turned ON and outputs a signal (step ST ₆ ), or whether switch SW ₂ B is turned ON and outputs a signal.
whether the signal was output (step
ST ₇ ). If a signal is output from at least one of the switches SW ₁ and SW ₂ , a command is output to the electric motor M ₁ to stop the truck 1 (step
_ST8 ). Moreover, the count value N ₁ i by encoder E ₁
is first recorded in the memory MEM as _N11 , and the target value of encoder _E3 is also set to _N31 (step _ST9 ). Note that the count value N ₁₁ corresponds to the distance L ₁ in FIG. 4A. Next, a command is output to the electric motor M ₃ to rotate the rotating body 5 to the right at the high angular velocity value V _h shown in Table 1 corresponding to the selected leg length (step ST ₁₀ ). Then, it is determined whether the time t ₁ in Table 1 corresponding to the leg length has elapsed (step ST ₁₁ ), and if the time t ₁ has elapsed, the rotating body 5 is moved to the lower position in Table 1 corresponding to the leg length. A command is output to electric motor _M3 to rotate it to the right at an angular velocity value _Vl (step _ST12 ). Then, it is determined whether the time t ₂ in Table 1 corresponding to the leg length has elapsed (step ST ₁₃ ), and if the time t ₂ has elapsed, it is determined whether the count value by the encoder E ₃ has reached N ₃₁ or not. Judgment (step
_ST14 ). As a result, if the count value has not reached _N31 , repeat steps _ST10 to _ST14 ,
When _N31 is reached, a command is output to the electric motor _M3 to stop the rotating body 5 (step _ST15 ),
At the same time, a command is output to turn off the power supply WS (step _ST16 ). Note that the steps ST ₁₀ to _{ST 14} select at least two set speed values (V _h and V _l ) from the 32 steps, and apply the selected speed values to the predetermined time t ₁ , respectively.
This corresponds to means F which is designed to sequentially and repeatedly output _t2 . Therefore, by steps ST ₆ to ST ₁₆ , the torch T
The rotating body 5 is rotated until it reaches the T'' position from the _{two -} dot chain line T _' position in FIG. The welding line WL ₁ will be welded by tracing. Next, the previous tracing control of the moving body 6 by the sensor SH is temporarily stopped (step ST ₁₇ ), and the target value of the encoder E ₄ is set to N ₄₁ . (Step ST ₁₈ ). Furthermore, a command is output to the motor M ₄ to move the moving body 6 away from the work W ₂ (Step ST ₁₉ ). Then, it is determined whether the count value by the encoder E ₄ has reached N ₄₁ . Judgment is made (step ST ₂₀ ), and if the count value reaches N ₄₁ ,
A command is output to electric motor _M4 to stop moving body 6 (step _ST21 ). Note that this stop position of the movable body 6 is approximately the same position as the above-mentioned origin position of the movable body 6, and the torch T is located at the solid line position in FIG. 4B. Next, an electric motor is used to move truck 1 backward at high speed.
A command is output to _M1 (step _ST22 ). Then, it is determined whether a certain period of time has elapsed (step
ST ₂₃ ), once the time has elapsed, a command is output to the electric motor M ₁ to stop the trolley 1 (ST 23 ).
_ST24 ). In other words, the truck 1 has been retreated to the position indicated by the two-dot chain line in FIG. 4B. Next, the target value of encoder E ₃ is set to N ₃₂ (step ST ₂₅ ), and a command is given to electric motor M ₃ to rotate rotating body 5 to the right at a high angular velocity (step ST 25).
_ST26 ). And the count value by encoder E ₃ is
Determine whether it has reached N ₃₂ (step ST ₂₇ ),
When the count value _N32 is reached, a command is output to the electric motor _M3 to stop the rotating body 5 (step _ST28 ). In other words, the rotating body 5 is rotated until the torch T reaches the position T'' from the position shown by the two-dot chain line T' in Figure 4B, and the stopping position of the rotating body 5 is changed from the position shown by the solid line in Figure 4B. This corresponds to the position that has just been rotated 90 degrees to the right.Next, in order to move the trolley 1 forward at a low speed, the electric motor
A command is output to _M1 (step _ST29 ). Then, the contact 9 of the sensor SH finally comes into contact with the work W ₂ and is pushed in. At this time, the output value from the transformer TR ₁ is taken into the CPU and the difference between this value and the reference value is determined (step ST ₃₀₎ . ). Then, it is determined whether the difference has become 0 (step ST ₃₁ ), and if it has become 0, the electric motor is activated to stop the trolley 1.
A command is output to _M1 (step _ST32 ). This stop position of the truck 1 corresponds to the position shown by the solid line in FIG. 4, and from this point on, the tracking control of the moving body 6 by the sensor SH is started again (step _ST33 ). Next, the target value of the encoder _E2 is set to _N21 (step _ST34 ), and a command is output to the electric motor _M2 to steer the wheel 2 to the right (step _ST35 ).
Then, it is determined whether the count value by the encoder _E2 has reached _N21 (step _ST36 ), and if the count value has reached _N21 , a command is output to the electric motor _M2 to stop steering the wheels 2. (Step ST ₃₇ ). As a result, all wheels 2 are steered 90 degrees to the right, and the front and back direction of the truck 1 is approximately at the weld line.
It will match the direction of WL ₂ . Next, move truck 1 backwards at medium speed (i.e. weld line
A command is output to electric motor M ₁ to cause the motor to approach WL ₁ (step ST ₃₈ ). Then, finally, trolley 1
The rear end of the workpiece W ₂ collides with the workpiece W 2 , but this collision is determined by whether both switches SW ₁ and SW ₂ are turned on and output signals (steps ST ₃₉ and ST ₄₀ ). When both switches SW ₁ and SW ₂ output signals, a command is output to motor M ₁ to stop truck 1 (step
_ST41 ). Therefore, even if the front-rear direction of the truck 1 does not exactly match the left-right direction in FIG. 4 when the truck 1 is moving backwards and is slightly tilted, when the truck 1 is stopped, one side of the truck 1 is completely aligned. work on
W ₂ is forced, and the slope is returned to zero. That is, the front-rear direction of the truck 1 exactly matches the left-right direction in FIG. 4.
The stopping position of the truck 1 at this time corresponds to the position indicated by the two-dot chain line in FIG. 4C. Next, the target value of the encoder _E3 is set to _N33 (step _ST42 ), and a command is output to the electric motor _M3 to rotate the rotating body 5 to the left at a medium angular velocity (step _ST43 ). Then, it is determined whether the count value by encoder _E3 has reached _N33 (step
_ST44 ), when the count value reaches _N33 , a command is output to the electric motor _M3 to stop the rotating body 5 (step _ST45 ). In other words, torch T is the fourth
The rotating body 5 is rotated to the left from the position shown by the two-dot chain line in FIG. 4 until it reaches the position shown by the solid line in FIG. Next, set the target value of encoder E ₃ to N ₃₄ (where N ₃₄ =
_N33 ) (step _ST46 ). Then, command the power supply WS to be turned on (step ST ₄₇ ),
Further, steps _ST48 to _ST51 execute the same contents as steps _ST10 to _ST13 described above. Then, it is determined whether the count value by encoder _E3 has reached _N34 (step _ST52 ), and if the count value has not reached _N34 , the steps ST48 to _ST48 described above are performed.
The contents of ST ₅₁ are executed repeatedly. Furthermore, when the count value reaches _N34 , a command is output to the electric motor _M3 to stop the rotating body 5 (step
_ST53 ). That _{is ,} until the torch T reaches the position shown by the solid line in FIG _. It will be profile welded. Next, a command is output to the electric motor _M1 to move the cart 1 forward at a welding speed V corresponding to the leg length (step _ST54 ), and counting by the encoder _E1 is also started (step _ST55 ). Then, determine whether (i=5) (step
ST ₅₆ ), and if (i≠5), then (i=i+
As 1) (step _ST57 ), the process returns to step _ST6 , and the contents of steps _ST6 to _ST57 are repeatedly executed. Note that the number of executions of step ST ₉ is 2, 3,
In the fourth case, the count values by encoder E ₁ at step ST ₉ are N ₁₂ , N 13 , and N ₁₃ , respectively.
It becomes _N14 . For N ₁₂ , each of these values is calculated from the position where the rear end of the truck 1 collides with the workpiece W ₂ forming the welding line WL ₁ in FIG. 4A.
corresponds to the distance L ₂ until the front end of collides with the workpiece W ₂ forming the weld line WL ₃ . In addition, for N ₁₃ , in Figure 4 A, the rear end of truck 1 is located at the weld line.
From the position where it collided with work W ₂ forming WL ₂ ,
Workpiece W ₂ whose front end of truck 1 forms welding line WL ₄
It corresponds to the distance L ₃ until the collision occurs. Plus _N14
In Fig. 4A, the front end of the truck 1 collides with _the work W 2 forming the weld line WL ₁ from the position where the rear end of the truck 1 collides with the work W ₂ forming the weld line WL ₃ . This corresponds to the distance L ₄ (L ₄ = L ₂ ). And if (i = 5), the truck 1 is at the welding line WL
This means that the welding line has passed through four bends, and welding is currently underway along the remaining welding line WL ₁ , excluding the first welded part. Therefore, (N ₁₃ −N ₁₁ ) is determined as N ₁₅ (step ST ₅₈ ). This value N ₁₅ corresponds to the distance L ₅ from the position where the rear end of the truck 1 collided with the workpiece W ₂ forming the welding line WL ₄ to the starting position indicated by the solid line in Fig. 4, and as a result, (L This is the same as finding L ₅ by setting ₃ − L ₁ )=L ₅ . Then, it is determined whether the count value by encoder _E1 has reached _N15 (step _ST59 ), and if the count value has reached _N15 , welding line _WL1 is
This means that only L ₅ was profiled and welded, so the power supply
A command is output to turn WS off (step
ST ₆₀ ), and an electric motor to stop the trolley 1.
A command is output to _M1 (step _ST61 ). This means that all four side weld lines WL ₁ to WL ₄ have been traced and welded. The above description is an example, and in the case of means F,
Three or more types of set speed values may be selected and each of these values may be sequentially and repeatedly output for a predetermined period of time. In addition, if the robot R is not a traveling trolley type but a rectangular coordinate system or an articulated coordinate system, and is a teaching play pack type, the speed value
A large number of values of V _h and time t ₁ and speed value V _l and time t ₂ are recorded in advance in the memory MEM, and the velocity components of each controlled axis are determined so that the welding speed is approximately constant. What is necessary is to output a value that approximates the value. It goes without saying that the replacement of each component with equivalents is also included within the technical scope of this invention. As described above, this invention arbitrarily selects at least two of the speed values that are set in stages, and sequentially outputs each of these selected values for a predetermined period of time. Since the value can also be output, even if a desired speed value cannot be set because a sufficient number of bits are not available for speed change, a desired speed value between approximately adjacent set speed values can be obtained.

[Brief explanation of the drawing]

The figures all show one embodiment of this invention, and the first
Figure 2 is a perspective view of the entire industrial robot, Figure 2 is a bottom view of the industrial robot's traveling carriage, Figure 3 is a block diagram of the control device, Figure 4 is an explanatory diagram of the operation, and Figure 5 is a flowchart. . In the figure, R...Industrial robot, 1...Traveling trolley, 2...Wheels (controlled axis), 5...Rotating body (controlled axis), C...control device, F...stepwise settings The present invention is a means for arbitrarily selecting at least two speed values and repeatedly outputting each of these selected values sequentially for a predetermined period of time.

Claims (1)

[Scope of utility model registration request] In an industrial robot control device capable of changing the speed of a controlled axis in steps, at least two types of stepwise set speed values are arbitrarily selected, and each of these selected values is sequentially and repeatedly output for a predetermined period of time. A control device for the industrial robot, comprising means for controlling the industrial robot.