JPH0428471B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the generation of a weaving pattern and the automatic continuation of the weaving pattern in a welding robot.

[Conventional technology]

As a method of realizing the so-called weaving motion in which the tip of the welding torch is swung along the teaching line of the welding robot, the welding robot uses a position input supported by the position servo of each drive shaft to move the welding torch along the teaching line with the weaving center. A method for weighing repetitive signals for weaving motion has been awarded a US patent.
This method has been proposed in Japanese Patent Publication No. 4188525 and Japanese Patent Application Laid-Open No. 56-89379. However, this conventional method, which uses an oscillator or a signal storage element as a repeating signal for weaving, has the drawback that a proper weaving pattern cannot be realized when the teaching line changes arbitrarily in three dimensions. This is because the repeating signal for weaving that should be given to each drive shaft position servo must not be a signal of constant amplitude and constant frequency.In the case of an articulated robot, a polar coordinate robot, or a cylindrical coordinate robot, where the teaching line is a straight line, It is easily understood if you consider.

Taking an articulated robot as an example, and considering the case where the welding torch tip is moved linearly as a result of the combined motion of each drive shaft, linear motion is only possible by interlocking control of each drive shaft, and each drive shaft position servo The applied position input signal is not a constant ramp or step signal, but a complex position input signal that fluctuates depending on the robot's posture from time to time.In order to obtain the desired weaving pattern, it must be input to each drive shaft position servo. The weaving repetition signal to be superimposed on the complex position input signal that is generated must of course change in a complicated manner depending on the posture of each drive shaft of the robot, so it cannot be realized with a simple oscillator.

Furthermore, it is practically impossible to store the weaving repetition signal as a position command to the position servo of each drive shaft using the signal storage element, as it requires an enormous storage capacity.

Furthermore, even if this conventional method allows for a restricted weaving motion, when a robot trajectory consisting of a large number of teaching lines is moved by weaving motion, a weaving repetition signal is required for each teaching line, which makes the teaching work difficult. This has the disadvantage that the operability becomes significantly worse.

[Problem to be solved by the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for controlling the weaving performance of a welding robot, which allows easy setting of teaching lines and improves the operability of teaching work.

[Means to solve the problem]

The present invention has been made to solve the above problems, and by controlling the three basic axes of the robot, it is possible to accurately execute a desired weaving motion for any teaching line within the robot operating area, and to perform a large number of weaving motions. When the robot moves along a weaving motion along the entire trajectory consisting of the teaching lines, by simply teaching the three weaving pattern definition points for the first teaching line, it is possible to make appropriate weaving movements for the subsequent teaching lines as well. This made it possible.

That is, the present invention teaches three points near the welding line for specifying the weaving pattern, and moves the triangular plane determined by these three points in the direction of the welding line to create the three-point weaving pattern.
The three basic axes of the welding robot are controlled so that the tip of the welding torch moves on one surface of the prism while executing a weaving motion determined by the weaving amplitude, frequency, and welding speed that are specified separately from the above three points. This is how it was done.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an example of an articulated teaching playback robot for carrying out the present invention, in which 1 is a consumable electrode type welding torch.

This welding robot is provided with a revolving body 5 having two bent arms 3 and 4 on a base 2, and a welding torch 1 attached to the tip of the arm 3 whose swing angle and twist angle can be changed by a drive motor. Weaving of the welding torch 1 is performed by controlling the three basic axes of the welding robot, namely, the arms 3 and 4 and the rotating body 5.

For convenience of explanation, a multi-jointed robot is taken up, but the present invention is not limited to multi-jointed robots, but can also be applied to other types of robots such as orthogonal robots, cylindrical robots, polar coordinate robots, etc. Of course there is.

Next, weaving motion using the three basic axes of the robot will be explained based on FIG. 2.

Before operating the robot, it is first necessary to teach the weaving direction, amplitude, frequency, and necessary conditions for welding.

Q ₁ , Q ₂ , near the weld line connecting teaching points P ₁ , P ₂ ,
By arbitrarily teaching the three points in Q ₃ ,
Set the weaving direction and width. 2 points Q ₁ ,
_Q2 only has a weaving surface for the weld line.
Since PL1 and the weaving center cannot be determined, the point
This is to set _Q3 .

In the present invention, a perpendicular line is drawn from Q ₃ to _{1 2} , its foot is H, and the weaving width J is specified separately on the extension line of _{1 2} with H as the center.
Find the points Q′ ₁ and Q′ ₂ where HQ′ ₁ =′ ₂ =j, and make the simple harmonic weaving of H→Q ₁ ′→H→Q ₂ ′→H... with equal amplitude from the center H. It is something to do.

For convenience, the following explanation is based on Q ₁ =
Q ₁ ′.

Intersection W of plane PL2 made by Q ₁ , Q ₂ , Q ₃ and _{1 2}
(x _w , y _w , z _w ) is P ₁ (x ₁ , y ₁ , z ₁ ) P ₂ (x ₂ , y ₂ , z ₃ ) P ₃ (x ₃ , y ₃ , z ₃ ) Q ₁ (x ₁ , y ₁ , z ₁ ) Q ₂ (x ₂ , y ₂ , z ₂ ) Q ₃ (x ₃ , y ₃ , z ₃ ) ………(1) (α, β, γ)……Q ₁ Q ₂ Direction cosine of --→ (α′, β′, γ′)……Q ₁ Q ₃ Direction cosine of --→ (λ, μ, ν)……P ₁ P ₂ --Direction cosine of → ...(2), then the position of W is x _w = f ₁ (x ₁ , y ₁ , z ₁ , x ₁ , y ₁ , z ₁ , α, β,
γ, α′, β′, γ′, λ, μ, ν) = x ₁ + λS _A = x ₁ + λS _A y _w = f ₂ (x ₁ , y ₁ , z ₁ , x ₁ , y ₁ , z ₁ , α, β, γ, α′,
β′, γ′, λ, μ, ν) = y ₁ + μS _A = y ₁ + μS _A z _w = f ₃ (x ₁ , y ₁ , z ₁ , x ₁ , y ₁ , z ₁ , α, β, γ, α′,
β′, γ′, λ, μ, ν) =z ₁ +γS _A …(3) However, SA=(x ₁ −x ₁ )(βα′−βα)+(y ₁ −y ₁ )(αα
′−α′α)+(z ₁ −z ₁ ) Sakaeαβ′−α′β)/λ(β
α′−β′α)+μ(αα′−α′α)+ν(αβ′−
α′β). The above P ₁ , P ₂ , Q ₁ , Q ₂ , and Q ₃ are taught points, and their coordinate values are known, so α, β, γ, α′, β′, γ′, λ , μ, ν, that is, x _w , y _w , and z _w can be easily determined using an arithmetic device.

In the present invention, the weaving center is H, but in order to make the explanation easier to understand, the intersection point W will be referred to as the weaving center in this description. In practice, as shown in Figure 3 a and b, W is often set to be on or near _{the three} lines, so the center in the amplitude direction is almost the same as H and W, so the intersection point is It is safe to think that W is mainly used for weaving.

This weaving center W traces above the teaching line P ₁ P ₂ ---→ in FIG.

Welding torch tip P attached to robot's wrist
does not follow the trajectory of W as shown in FIG. 2, but follows a trajectory obtained by adding the WH vector and the current weaving value from H to the momentary value of W.

In order to find the weaving point coordinates after K times of the reference clock starting from H, the distance S that the tip of the welding torch moves over one reference clock _{12 '} is determined.

The reference clock referred to here is a signal generally called a servo clock, and is the output signal of the frequency division/rise differentiation circuit 37 shown in FIG.

The details will be described later in the explanation regarding FIG.
The output of BRM (Binary Rated MultiPlier) in the same figure,
In other words, it is a clock having a period in which the position servo command as a pulse train signal to the position servo system of each axis constituting the robot is completed in a time determined by the clock φ shown in the figure and the number of BRM bits. The period is called the reference clock period.

The next position servo command data for each axis within this reference clock cycle, that is, the buffer 41 shown in the figure.
The input data to is calculated by the calculation unit 31. Note that this calculation clock cycle is usually set to several ms,
The amount of movement of each axis of the robot is calculated incrementally every cycle of this reference clock, and a fine weaving motion is performed.

To perform the weaving motion, initially set this K to K=1, and then change K=1 every reference clock period.
K is incremented to a value of K+1.

Here, if the reference clock period is C ₀ , the number of weaving frequencies is h, and half of the weaving amplitude is j, then S = 4hjC ₀ ... (4) The X, Y, Z components Δx, Δy, Δz of S are Δx =-Sα Δy=-Sβ Δz=-Sγ ...(5) Furthermore, the current values x _K , y _K , and z _K on the weaving pattern after K reference clock cycles are expressed as x _K =K·Δx y _K =K·Δy z _K =K·Δz (6). In addition, when returning from the weaving Q ₁ , Q ₂ ′ of H→Q ₁ →H→Q ₂ ′→H, Δx, Δy,
It is natural to reverse the sign of Δz. The length and direction of WH―→ are always constant, and its components x ₀ , y ₀ , z ₀
is x ₀ =x ₁ +jα−x _w y ₀ =y ₁ +jβ−y _w z ₀ =z ₁ +jγ−z _w ……(7).

Therefore, the welding torch tip P should just follow a trajectory obtained by adding the coordinates of the weaving center W to equations (6) and (7).

If the specified welding speed is V, the amount of movement per reference clock for the weaving center W to follow P ₁ P ₂ -→ is: It is expressed as

The distance x _K ′, y _K ′, z _K ′ that the weaving center W moves after K reference clocks is x _K ′=x ₁ +x _op・K y _K ′=y ₁ +y _op・K z _K ′=z ₁ +z _op・K ...(9) becomes.

The coordinates of the welding torch tip, which is the control point (X _K ,
A desired weaving pattern can be obtained by controlling Y _K , Z _K ) to satisfy the following equation.

X _K = x _K ′+x _K +x _p Y _K = y _K ′+y _K +y _p Z _K =z _K ′+z _K +z _p (10) Next, the control of the robot's wrist axis will be explained.

The wrist posture must be controlled so that the torch angle and advancement angle along the welding line are within a certain range of variation determined by welding. Naturally, the wrist posture at the teaching points P ₁ and P ₂ has been taught correctly. The values at points P ₁ and P ₂ of the hair swing axis B and twist axis T _{are 1} , ₁ ,
As B ₂ and ₂ , the increment amounts ΔB and ΔT per reference clock C ₀ are obtained from the following equations.

Therefore, B _{K and} T _K of the K-th reference clock are controlled as much as B _K = B ₁ + ΔB・K T _K = T ₁ + ΔT・K (12), and the proper welding torch posture is always maintained during weaving. dripping

Since the X, Y, and Z coordinates in equation (1) are the coordinates of the tip of the welding torch, which is the control point, in order to obtain equation (1),
Regardless of whether the robot is orthogonal, multi-jointed, cylindrical, or polar coordinate, P ₁ , which is stored in memory,
It is necessary to convert the drive axis coordinate data of P ₂ , Q ₁ , Q ₂ , and Q ₃ to orthogonal coordinates.

In addition, the position (X _K ,
Solution of equation (10) to realize Y _K , Z _K , B _K , T _K )
X _K , Y _K , and Z _K must be converted back to drive axis data for the robot's basic axes. The robot wrist axis data is B _K and T _K.

The basic three axes of the embodiment robot shown in FIG.
are controlled by rotation angles ψ, θ, respectively, and the wrist swing axis and twist axis are controlled by rotation angles B and T. Control point P is the tip of welding torch 11.

Since the point P that is a distance A from the wrist swing axis rotation center and a distance d away from the twist axis rotation center is the taught control point, its orthogonal coordinate value is X = (Lcosθ + lcos + AsinB + dcosT・cosB) ×
cosψ−dsinT・sinψ X=(Lcosθ+lcos+AsinB+dcosT・cosB)×
cosψ−dsinT・sinψ Y=(Lcosθ+lcos+AsinB+dcosT・cosB)×sinψ
−dsinT・cosψ Z=Lsinθ+lsin+AcosB+dcosT・sinB ...(13) In addition, X _K , Y _K , Z _K obtained by equation (10) and (12)
From B _K and T _K obtained by the equations, the rotation angles of the three basic axes of the articulated robot ψ _K ,
θ _K and _K are found.

However, a=√ _K ² + _K ² − ^{2 2} _K − (AsinB _K + dcosT _K cosB _K ) b=Z _K (AcosB _K − dcosT _K sinB _K ) Figure 4 is used to explain the automatic continuation of the weaving teaching pattern. This is a diagram. In the figure, P ₁ , P ₂ ,
P ₃ is the teaching point as in Fig. 2, and Q ₁ , Q ₂ ', and Q ₃ mean exactly the same as in Fig. 2.

₁ Take P _e on the extension line of ₂ . P ₁ and ΔQ ₁ Q ₂ ,
When Q ₃ is moved in parallel along _{1 2} and P ₁ is brought to P ₂ , Q ₁ and Q ₂ will be at the _{10 20} position.
P ₂ P Draw direction ₂ perpendicular to the plane made by ₃ and ₂ . However, ₂ is taken in the direction of the cross product of the two vectors P ₂ P ₃ and P ₂ Pe. As ∠P ₃ P ₂ Pe=ω ₀
By rotating Q ₁₀ Q ₂₀ ' by ω ₀ in the direction _{from 2 to 2 3} around the axis of 2, the weaving pattern _{1 2} of the next block can be found.

Are the coordinate values of P ₁ ( ₁ , ₁ , ₁ ), P ₂ ( ₂ , ₂ , ₂ )?
Find the direction cosine (λ, μ, ν) of P ₁ P ₂ and calculate P ₂ ( ₂ ,
When the direction cosine (λ', μ', ν') of P _{2 P 3 is determined from the coordinate values of y 2 , 2 ) and P 3 ( 3 , 3 , 3 )} , ω ₀ is defined by the following equation.

ω ₀ = f ₁₆ (λ, μ, ν, λ′, μ′, ν′) = cos ^-1 (λλ′, μμ′, νν′) ... (15) Coordinates of Q ₁ , Q ₂ , Q ₃ The values are (x ₁ , y ₁ ,
₁ when z ₁ ), (x ₂ , y ₂ , z ₂ ), (x ₃ , y ₃ , z ₃ )
(x ₁ ′, y ₁ ′, z ₁ ′) is defined by the following equation.

x ₁ ′=f ₁₇ (x ₁ , x ₂ , x ₁ , y ₁ , z ₁ , ω ₀ , λ, μ, ν, λ′, μ′, ν′) = X ₂ + (X ₁ , X ₁ ) cosω ₀ + (μν′−μ′ν)m/1
+cosω ₀ − (λμ′-λ′μ) (Y ₁ -Y ₁ ) + (νλ′-ν′λ)
(Z ₁ , Z ₁ ) y ₁ ′=f ₁₀ (y ₁ , y ₂ , x ₁ , y ₁ , z ₁ , ω ₀ , λ, μ, ν, λ′, μ′, ν′) = Y ₂ +(Y ₁ , Y ₁ )cosω ₀ +(νλ′−ν′λ)m/1
+cosω ₀ − (μν′−μ′ν) (Z ₁ , Z ₁ ) + (λμ′−λ′μ
_{) ( X 1 − _ _ _ _ _ 2} + (Z ₁ − Z ₁ ) cosω ₀ + (λμ, −λ′μ) m/1
+cosω ₀ − (νλ′-ν′λ) (X ₁ -X ₁ ) + (μν′-μ′ν)
(Y ₁ -
Y ₁ ) ...(16) However, m = (x ₁ − ₁ ) (μν′−μ′ν) + (Y ₁ − ₁ ) (νλ′−ν′λ) + (Z ₁ − ₁ ) (λμ ′-λ′μ) cosω ₀ =λλ′+μμ′+νν′ ₂ ′ (x′ ₂ , y ₂ ′, z ₂ ′), ₃ (x ₃ , y ₃ , z ₃ ) can be found in the same way. Teaching the weaving pattern and width only needs to be done once on the first welding line, and in subsequent blocks sequentially determine Q ₁ , Q ₂ , and Q ₃ .
Weaving is automatically continued in the appropriate direction by repeating what has been explained in FIG. Even if there is an air cut block on the way that does not perform weaving, the above calculation continues, so there is no need to teach weaving points Q ₁ , Q ₂ , and Q ₃ even on the weld line after air cutting. In other words, Q ₁ ,
Teaching Q ₂ and Q ₃ only needs to be done once.

FIG. 5 shows an arithmetic unit in an embodiment of the present invention,
FIG. 2 is a block diagram showing the connection between each drive shaft position servo controller of the robot composed of a BRM with a two-stage buffer and the main CPU (microprocessor) that controls the operation of the entire robot.

When performing weaving welding from the entire robot operation sequence in response to a command request from a computing unit, the main CPU 20 selects the starting point P ₁ , ending point P ₂ and weaving pattern definition point of the block to be weaved specified in a teach box (not shown). The number of pulses from the origin of the three robot basic axes Q ₁ , Q ₂ , and Q ₃ and the robot wrist axis, the welding speed V, and the weaving frequency h are read from the memory (not shown), and are stored in registers 21 to 27.
It has a function to set the macro command to start weaving and output the weaving start macro command.

The arithmetic unit 31 includes a sequence controller 32,
Microprogram memory 33, pipeline register 34, multiplexer 35, RALU
(Register and Arithmetic Logic Unit) 3
6. Registers 21 to 27, frequency division of clock φ, rising differentiation circuit 37, and reference clock.
It is composed of an address generator 38.

The sequence controller 32 is an address controller that controls the execution sequence of microinstructions stored in the microprogram memory 33. Pipeline register 3
Various addressing and stack controls are performed by control commands from 4.

More specifically, incrementing the address currently being executed, selecting an address specified by a macro command, and incrementing the address specified by the reference clock address generator 3.
Selection of the address specified in 8, selection of the jump address given from the pipeline register 34 in the case of a conditional jump according to the test conditions including the RALU status, selection of the jump address given from the pipeline register 34 in the case of an unconditional jump. This is the part that processes jump address selection, stack control during micro subroutine calls, etc.

Input information for addressing is
There are three: a macro command from the CPU, the output of the reference clock address generator 38, and the output of the pipeline register 34.

The microprogram, ie, the control command of the pipeline register 34, determines which of these three the sequence controller 32 will select, or whether it will select none and increment the current address.

There is a weaving start command as a macro command. From a hardware standpoint, this macro command and the output of the reference clock address generator 38 are given in a form indicating the start address of each processing microprogram. When these are not provided to the sequence controller, the jump address, subroutine call address, and current address increment are provided from the pipeline register 34 output.

The microprogram memory 33 is the main arithmetic unit 31
In the central part of the computer, all arithmetic processing is executed according to the instructions of this microprogram.

The pipeline register 34 RALUs the arithmetic microinstruction to be currently executed in the buffer register of the microprogram memory 33.
36, a control command for determining the next microaddress is output to the sequence controller 32 and the multiplexer 35, and a jump address, subroutine call address, and current address increment are output to the sequence controller 32. When the weaving center reaches the end point _P2 of the block, a command request for coordinate data of the next block is output to the main CPU 20.

This pipeline register 34 is provided to form two signal paths and allow each signal to proceed simultaneously in parallel to shorten microcycle time and speed up calculations.

In other words, one path is a control system path connecting pipeline register 34 → sequence controller 32 → microprogram memory 33, and the other path is pipeline register 34 →
A pipeline register 34 is provided in the arithmetic system path of the RALU 36 in order to operate these two paths in parallel during the same clock cycle.

When the clock CP rises, the next instruction of the microprogram prepared in the control path has already appeared at the input of the pipeline register 34, so high-speed operation equivalent to zero memory fetch time is possible.

Multiplexer 35 is pipeline register 3
The test condition of the RALU status is given to the sequence controller 32 in response to the control command No. 4, and the condition jump to each processing program is executed.

The RALU 36 is composed of a logical/arithmetic operation unit and a programmable register, and executes operation instructions specified by a microprogram. The calculation result, which is the incremental number of pulses for each drive axis of the robot for each reference clock, is stored in a predetermined register in the RALU 36.

Register 21 is the starting point P ₁ , register 22 is the ending point
P ₂ , register 23 has Q ₁ point, register 24 has Q ₂ points,
The register 25 is a register that stores the number of pulses from the three basic axes of the robot at the _Q3 point and the origin of the robot wrist.

The register 26 is a register that stores the welding speed V, and the register 27 is a register that stores the weaving frequency h. Buffer 41 is a register that stores the number of incremental pulses to be delivered at the next reference clock for each drive axis of the robot, and buffer 42 is a register that stores the number of incremental pulses that are currently being delivered.

The BRM uniformly distributes the number of pulses stored in the buffer 42 within a reference clock period as pulses synchronized with the clock φ, and outputs a buffer transfer payout completion signal for each reference clock.

Frequency division and rise differentiation circuit are from clock φ
This circuit creates a reference clock whose frequency is divided by the number of BRM bits and differentiates its rising edge, and is used to synchronize the BRM output completion signal and the reference clock.

Figure 6 shows the basic three axes (ψ axis, θ axis, axes) and two wrist axes (B axis, T axis) of an articulated robot that is controlled by command pulses issued from the BRM explained in Figure 5. It is a position servo.

Each axis command pulse and each pulse generator are given to make the welding torch tip perform weaving motion.
The difference with the feedback pulse from 616, 626, 636, 646, 656 is the deviation counter 611, 621, 631,
Output from 641, 651 and D/A converters 612, 622,
Analog speed commands are input to servo amplifiers 613, 623, 633, 643, and 653 via 632, 642, and 652, respectively. The servo amplifier compares the speed command with the outputs (detected speeds) of the tacho generators 615, 625, 635, 645, and 655, respectively, and controls each drive motor so that the difference disappears. With this position servo system, the tip of the welding torch mounted on the robot follows the command pulses and performs the desired weaving operation.

Next, weaving control operation by the control circuit shown in FIG. 5 will be explained.

The computing unit 31 is initially executing a wait routine. The sequence controller 32 is the main
When a macro command is given from the CPU 20,
While being given a control command from the pipeline register 34 to select the start address of the service program, the arithmetic unit 31 performs address control to execute the wait routine.

Since this wait routine contains an instruction to reset the reference clock frequency divider circuit 37, no reference clock is generated.

Main points to start weaving control
The CPU 20 first registers 21 to 25.
, the starting point P ₁ ( ₁ , ₁ , ₁ ,
T ₁ , ₁ ), end point P ₂ ( ₂ , ₂ , ₂ , ₂ , ₂ ), weaving pattern definition point Q ₁ (ψ ₁ , θ ₁ , ₁ , T ₁ ,
B ₁ ), Q ₂ (ψ ₂ , θ ₂ , ₂ , T ₂ , B ₂ ), Q ₃ (ψ ₃ , θ ₃ ,
₃ , T ₃ , B ₃ ).

Further, the welding speed V and weaving frequency h are set in the register 26 and the register 27.

When the main CPU 20 outputs a weaving start macro command, the start address N# of the weaving control service microprogram is selected.

This program includes the reference clock divider circuit 3.
Since the command to cancel the reset signal of 7 is included,
The frequency dividing circuit 37 starts counting the clock φ.
Thereafter, the sequence controller 32 is operated until the next output from the reference clock address generator 38 is received.
operates to perform addressing necessary for arithmetic processing.

Next, let's explain the weaving control program starting with N#.

P ₁ , P ₂ , Q ₁ , Q ₂ , set in the register
Convert Q ₃ to the orthogonal coordinate system data shown in equation (1) using equation (13). Next, solve equations (4) and (5) using h set in register 27. Also, equation (8) is solved using V set in the register 26. Also, equation (2) and
Solve equation (3) and then solve equation (7).

Solve equation (11) using the wrist axis angles of P ₁ and P ₂ . Assume that the first address where the subsequent processing programs are stored is M#.

For the first reference clock, set K=1 and solve equation (6). Find X _K , Y _K , and Z _K in equation (10) from equations (9) and (7). Find B _K and T _K from equation (12).

The difference ΔB, ΔT between the solution B _K , T _K of equation (12) and B _K , T _K ( ₁ , ₁ in this case) at the previous reference clock
is set in a predetermined register in the RALU 36.

Substitute the solution of equation (10) X _K , Y _K , Z _K and B _K , T _K into equation (14) to find the basic three axes ψ _K , θ _K , _K , and calculate ψ _K at the previous reference clock. , θ _K , _K (in this case ₁ , ₁ ,
₁ ), the differences Δψ, Δθ, and Δ are set in predetermined registers in the RALU, and the computing unit 31 waits.

Unlike the wait routine that waits for a macro command from the main CPU 20, this wait routine waits for the next reference clock address generator output M#, and the frequency divider circuit 37 is not reset.

The clock φ and BRM are
Since the number of bits is set, there is no problem of not being able to complete the calculation in time.

While the arithmetic unit 31 is executing a wait routine waiting for M#, the reference clock is generated and at the same time
A payout completion signal is output from the BRM, and Δψ, Δθ, Δ, ΔB, and ΔT are respectively loaded into the five buffers 41 from predetermined registers in the RALU 36, and the contents of the buffer 41 are loaded into the buffer 42.

Since the buffer 41 remains cleared at the first reference clock, 0 is stored in the buffer 42, and no pulse is delivered by the BRM. The reference clock address generator 38 is activated by this reference clock, and the microprogram starts running from M#, setting N=2 to obtain equation (6).

Therefore, find equation (9) and find X _K , Y _K , and Z _K in equation (10). In addition, B _K and T _K in equation (12) are determined, and the differences ΔB and ΔT from the previous time are set in predetermined registers in the RALU. Substitute these X _K , Y _K , Z _K and B _K , T _K into equation (14) to find ψ _K , θ _K , _K , and calculate the difference Δψ, Δθ from the previous time,
Set Δ to a predetermined register in RALU.

Thereafter, the arithmetic unit waits for the next reference clock address generator output M#.

At the next reference clock, the contents of the previous buffer 1 are loaded into the buffer 42, the current values of Δψ, Δθ, Δ, ΔT, and ΔB are loaded into the buffer 41, and command pulses are sent out to each axis position servo by the BRM. .

Next, the arithmetic unit calculates ψ _K , θ _K ,
_K , T _K , and B _K are obtained, and position servo control is performed based on the differences Δψ, Δθ, Δ, ΔT, and ΔB from the previous reference clock.

When the weaving center reaches the end point _P2 of the block, the arithmetic unit 31 determines the weaving direction for the next block, and performs weaving pattern continuation processing so that the weaving width becomes equal to the weaving width of the previous block. That is, the direction cosine (λ, μ, ν) of P ₁ P ₂ ---→ that was already found in the previous block and P ₂ P ₃ ---
Find ω ₀ in equation (15) using the direction cosine (λ', μ _' , _ν ') of Find ′ ₁ , y′ ₁ , z′ ₁ . Similarly, find ₁ point and ₃ points and calculate Q ₁ , Q ₂ , Q ₃ in equation (1).
Replace.

After that, in response to a command request from the arithmetic unit 31, the main CPU 20 sets the coordinate values of the end point _P2 of this block in the register 21, and then sets the number of pulses from the origin of the robot's 5 axes at the end point of the next block in the register 22. A weaving start macro command is given to the arithmetic unit 31. After that, the above operation is repeated.

Furthermore, since the next segment data is always stored in the buffer 41 while discharging command pulses by the two-stage buffer, there is no stop between blocks even when a block switching point is reached, and smooth weaving welding is realized.

〔Effect of the invention〕

As explained above, according to the present invention, any welding line can be applied to any welding line within the entire operating range of the welding robot by simply teaching the teaching line, teaching only three points, and specifying the amplitude and frequency (usually specified by a key switch). Appropriate weaving movement is possible even for 2
Since the same weaving pattern is automatically continued for the second and subsequent welding lines, special teaching for weaving for the second and subsequent welding lines is not required, greatly improving the workability of weaving teaching and improving the welding robot. This greatly contributes to the driving operation of cars.

[Brief explanation of drawings]

Figure 1 is a perspective view of an earth welding robot for implementing the present invention, Figure 2 is an explanatory diagram of teaching points for setting weaving motion, Figure 3 is an explanatory diagram showing an actual teaching example, and Figure 4 is an illustration of weaving motion setting. FIG. 5 is a block diagram of the control circuit in the embodiment, and FIG. 6 is a block diagram of the servo control section in the embodiment. 1... Welding torch, 2... Foundation, 3 and 4...
Arm, 5...Swivel body.

Claims (1)

[Claims] 1. Near any one of the plurality of teaching lines,
Three points for specifying the weaving pattern, namely two points Q ₁ for determining the weaving surface PL1,
In addition to teaching Q ₂ and one point Q ₃ for determining the weaving center, we also specify the weaving amplitude, frequency, and welding speed separately from the three points above, and control the three basic axes of the welding robot to adjust the tip of the welding torch. is moved on the weaving surface PL1 of the triangular prism, which is formed by moving the triangular plane PL2 determined by the teaching of the three points in the direction of the teaching line, with the specified weaving amplitude, frequency, and welding speed. Features: Weaving control method for welding robots. 2. By teaching three points that define weaving motion in the vicinity of the first welding line, and performing three-dimensional translation plus rotation calculations on the surface formed by the three points for the second and subsequent welding lines. The weaving control method for a welding robot according to claim 1, characterized in that the weaving pattern is automatically continued.