JPH0416272B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a teaching playback welding robot that teaches welding lines using the PTP method, and particularly to a weaving pattern teaching method.

Teaching Playback's arc welding robot (1) obtains a large amount of weld metal in one pass for workpieces with medium-thickness plates with wide grooves, and melts the wall surface that makes up the grooves to produce an appropriate welding process. Obtain the welding result. (2) For target workpieces with gaps between thin plates, fill the gaps. (3) If there are variations in the welding line due to variations in each target workpiece, we can reduce the variations to some extent. Absorb,
(4) So-called weaving motion, in which the tip of a welding torch attached to the tip of a robot wrist is swung, is widely used for purposes such as sensing means in arc sensing.

This robot's weaving movement method includes:
The so-called hard weaving method involves gripping a welding torch by a special weaving device attached to the robot's wrist, and moving the tip of the welding torch in a weaving motion using this weaving device.
There is a so-called soft weaving method in which a weaving motion is performed based on software means as a combined motion of the axis or each axis. Although the hard weaving method allows for high-speed weaving motion, it has the disadvantage that the welding torch cannot access the narrow welding line of the workpiece due to the special weaving device attached to the robot's wrist. There are also restrictions on the direction of. On the other hand, the soft weaving method does not require a special weaving device to weave the robot's existing axis, provides easy access to the weld line of the target workpiece, and reduces the weight of the robot's wrist. It has the advantages of increased durability and no restrictions on the weaving direction.

Conventionally, with this soft weaving method, it is necessary to teach the welding line as well as two or three weaving end points that define the size, direction, etc. of the weaving movement. For a line, it is necessary to teach all the weaving end points, and it takes a long time to teach the number of weaving end points. Furthermore, if the amplitude of the weaving is small, it is difficult to teach the weaving direction and amplitude correctly, and due to the constraint that the weaving end point must be taught near the welding line, it is difficult to weld the inside of the structure etc. Even if the welding torch is able to enter the inside of the welding torch, it is difficult for the operator to visually see the tip of the torch, making it extremely difficult to teach the teaching location, weaving direction, size, etc.

In this way, the teaching work of the soft weaving method is not only a detailed and patient work, but also
When there are a large number of weld lines that undergo weaving motion, this becomes a factor that reduces work efficiency.

The present invention was proposed in view of the above problems, and does not directly teach the weaving end point to the weld line, but teaches one auxiliary point at an arbitrary position on or near the workpiece, and connects the weaving end point to the weld line. The purpose of the present invention is to provide a weaving pattern teaching method for a welding robot that automatically determines the coordinates in the robot space coordinate system of each weaving end point of the weaving pattern simply by numerically specifying distances, angles, etc. that define the positional relationship. do.

The weaving pattern teaching method for a welding robot according to the present invention is to set a reference pattern of a predetermined triangle △ABC in advance, and apply any of the taught welding lines to any position on or in the vicinity of a workpiece set in a jig. line segment
Q _o Teach an auxiliary point P _o corresponding to Q _o+1 , and on the line segment _{o o+1} , find the angle that the auxiliary line _{o o} connecting to the auxiliary point P _o makes with the line segment _{o o+1.} Set a point S _o so that the angle ζ is a predetermined angle, and set the apex A' of a triangle △A'B'C' that is congruent with the reference pattern at the point S _o ,
The vertex B' is set on the auxiliary line _{o o} , the apex C' is set so that the angle between the line segment '' and the line segment _{o o+1} is a predetermined angle α, and the triangle △A'B' A triangle △A″B″C″ obtained by moving C' by a certain vector amount is used as a weaving pattern corresponding to the line segment _{o o+1} .

If a reference line _{r r} corresponding to another line segment _{r r+1} of the taught welding line has already been obtained, make this reference line _{r r} parallel to any point on the line segment _{o o+1.} The moved line segment can be used as the reference line corresponding to the line segment _{o o+1} , and there is no need to newly teach an auxiliary point.

If the reference pattern is a polygon other than a triangle, use the reference pattern of a predetermined polygon larger than a quadrilateral □
ABCD... is set in advance in the robot space coordinate system, and any line segment of the taught welding line is placed at any position on or near the workpiece set in the jig.
Q _o Q _o+1 is taught an auxiliary point P _o , and the angle between the auxiliary line _o o connecting the auxiliary point P _o and _the line segment _{o o+1} on the line segment _{o o+1} is Determine a point S _o so that it forms a predetermined angle ζ, and draw the polygon □
The apex A' of the triangle △A'B'C' formed by any three vertices of the polygon □A'B'C'D'... which is congruent with ABCD... is set at the point S _o , and the apex B' is set at the auxiliary line _{o o} defined above, line segment
The vertex C' is determined so that the angle between A'C' and the line segment _{o o+1} is a predetermined angle α, and the polygon □
Other vertices D′,… of A′B′C′D′… are the triangle △
The polygon □A″B″C″D″… which is determined based on A′B′C′ and the obtained polygon □A′B′C′D′… is moved by a certain vector amount is the line segment _o
The weaving pattern corresponds to Q _o+1 .

Hereinafter, the present invention will be explained with reference to drawings of embodiments. This example is based on a predetermined triangle △ABC (line segment = L ₁ , line segment = L ₂ , ∠BAC =
Using β) as a reference pattern, the web 1 and flange 2 are welded while performing simple harmonic or triangular weaving motion along welding lines _{1 2} and _{2 3} as shown in FIG. In this case, first, point S _o is a triangle △
After matching the vertex A′ of A′B′C′, this triangle △
Triangle △ where A′B′C′ is moved by a certain vector amount
_A ″ _B ″C″ is _the weaving pattern for _{welding lines 12 , 23.Q1} is _the welding start _{point.Points Q1} ,
Q ₂ and Q ₃ are taught and the robot's Cartesian coordinate system 0-
The xyz coordinate values are (X ₁ , Y ₁ , Z ₁ ), (X ₂ ,
Y ₂ , Z ₂ ), (X ₃ , Y ₃ , Z ₃ ). Point P ₁ is an auxiliary point taught on the surface of web 1 to define the weaving end point, and is located in the orthogonal coordinate system 0 of the robot.
Let the coordinate values at −xyz be (X ₁ ′, Y ₁ ′, Z ₁ ′). point
A′, B′, C′ are the weaving end points to be calculated, and weaving end point A′ is the welding line from the auxiliary point _P1.
The intersection of the perpendicular line drawn to Q ₁ Q ₂ and welding line _{1 2} , weaving end point B′ is a single weaving point on perpendicular line ′ ₁
It is a point that is a specified distance L ₁ (= line segment) away from A′. The coordinates of the weaving end point A′ are
Let X _A ′, Y _A ′, Z _A ′ be.

First, the coordinate values X _B ', Y _B ', and Z _B ' of this weaving end point B' in the robot's orthogonal coordinate system 0-xyz are calculated. Each coordinate value of point Q ₁ and point Q ₂ (X ₁ , Y ₁ ,
Z ₁ ), (X ₂ , Y ₂ , Z ₂ ), _the direction cosines h, i, and j of _line segment _{1 2} are the coordinate values (X ₁ ,
The direction cosines l, 'm', and n' of _{the line segment 11 are} obtained from _Y1 , _Z1 ) and (X1 _' , _Y1 ', _Z1 '), respectively. From these two direction cosines h, i, j and l', m', n', ∠
We can find the cosine value of P ₁ Q ₁ Q ₂ and calculate its sine value using the theorem of trigonometric functions. That is, the direction cosines l, m, n of the perpendicular ' ₁ are the direction cosines h, i,
Functions of j, l′, m′, n′, l=f ₁ (h, i, j, l′, m′, n′) m=f ₂ (h, i, j, l′, m′, n') n=f ₃ (h, i, j, l', m', n') ...(1). Therefore, the weaving end point
The _{coordinate values} of _{B ′} are X _{B ′ , Y B} ′, and _{Z B ′} . ...(2) becomes.

Next, the coordinate values of the weaving end point C′ are X _C ′, Y _C ′,
Calculate Z _C ′. Here, the angle between the line segments ′′ and ′′ is β, which is the same as the angle between the line segment of triangle △ABC, the angle between the line segment ′′ of weld line _{1 2} is α, and the angle between weld line _{1 2} and the perpendicular line ′ The angle formed by ₁ is ζ (which is 190° according to the above definition). The direction cosines a, b, c of the line segment '' are the direction cosines h, i, j, l,
Function a=g ₁ (h, i, j, l, m, n, α, β, ζ) b=g ₂ (h, i, j, l, m, n, α, β, ζ) c=g ₃ (h, i, j, l, m, n, α, β, ζ) ...(3). Therefore, the coordinate values X _C ′, Y _C ′, and Z _C ′ of the weaving end point C′ are X _C ′=X _A ′+L ₂・a Y _C ′=Y _A ′+L ₂・b Z _C ′=Z _A ′+L ₂・c ……(4). Here, L ₂ is the distance of a line segment ′′ taken equal to the designated line segment of triangle ΔABC.

In this way, weaving end point A′ (X _A ′, Y _A ′,
_The coordinate values of the weaving _end points _B ′ and C′ with Z _A ′) as _{the reference} point are expressed as Equation (2 ₎ ,
Calculated using (4). Weaving each end point B′,
In order to realize C′ around the welding start point Q ₁ , instead of the coordinate values X _A ′, Y _A ′, Z _A ′, the coordinate values X ₁ , Y ₁ , Z ₁ of the welding start point Q ₁ are expressed as Substituting into (2) and (4), point B′,
All you have to do is find the coordinate values of C′, X _B ′, Y _B ′, Z _B ′, X _C ′, Y _C ′, and Z _C ′. If we define the weaving end points A', B', and C' in relative positions to weld line _{1 2} , weaving end point A' is always on weld line _{1 2} , so
Assuming that X _A ′=Y _A ′=Z _A ′=0, from equations (2) and (4), the coordinate values of weaving end points B′ and C′ are X _B ′, Y _B ′, Z _B ′,
All you have to do is find X _C ′, Y _C ′, and Z _C ′.

Next, a method for ensuring that the weld line ₁₂ always penetrates the center of gravity of _the triangle ΔA'B'C' connecting the weaving end points A', B', and C' will be described. First, set the weaving end point A' on _{the welding line 12 and} find the coordinates of the center of gravity of the triangle △A'B'C'.
Next, each weaving end point only has the coordinates of its center of gravity.
By moving A′, B′, and C′ in parallel, the coordinate values of the weaving end points A″, B″, and C″ can be obtained. In other words, in equations (2) and (4), X _A ′ ＝Y _A ′＝
Assuming Z _A ′=0, X _B ′, Y _B ′, Z _B ′, X _C ′, Y _C ′,
Find Z _C ′ and calculate these coordinate values X _B ′, Y _B ′, Z _B ′, X _C ′,
_{Y C ′ , Z C ′ as _ _ _} )/3 ...Coordinate values obtained by substituting into (5) (X _A ″, X _B ″, X _C ″)
is the triangle △ connecting weaving end points A′, B′, and C′
These are the coordinate values of weaving end point A″ when welding line _{1 2} penetrates the center of gravity of A′B′C′. The coordinate values of weaving end point B″, C″ are the calculated X _A ″, X _B ″, X _C ″
The weaving pattern △A″B″C″ obtained by substituting into equations (2) and (4) is particularly effective for triangular weaving.The denominator on the right side of equation (5) is “3”.
If you change “2” and perform the same process, the line segment
It is possible to find the coordinate values of each weaving end point A″B″C″ when welding line _{1 2} passes through the midpoint of B′C′.This method can be used for simple harmonic weaving in which ″″ Particularly effective.

By the way, among the parameters used in equations (1) to (5), the distances L ₁ , L ₂ , and angles α and β are values that can be easily grasped by looking at the actual welding groove line. You can enter numerical values with etc. The angle α is normally 90°, but a feature of the present invention is that it can be specified as any angle in special cases. Note that the distances L ₁ , L ₂ and the angle β are the vertices A,
Although the characteristic values are determined by B and C, distances L ₁ , L ₂ , and angle β can be calculated by specifying only the length of three sides or one side and two angles according to the triangle theorem. is merely a variation of the invention.

Next, in FIG. 1 _{, it is assumed that the weaving movement at weld line 12 has} ended and point _Q2 has been reached.
As shown in FIG. 1, when the next welding line ₂₃ is not on the extension line of the welding line ₁₂ , conventionally each weaving end point A', _B ', C' is re _- taught at a new point _Q2 .
However, in the present invention, the direction _cosines l, m,
If n can be considered to be almost the same as in the case of welding line _{1 2} , there is no need to newly teach auxiliary points on the surface of web 1, for example. One example of this application is when the flange 2 is made of a single steel plate and the angle material that makes up the web 1 is welded to it, and this is actually one of the most frequently used examples in industry. be. In this way, if the above conditions are satisfied regarding the weld line _{2 3} , the direction cosines l, m, and n of the perpendicular line ' ₁ to the weld line _{1 2} are also applied to the weld line _{2 3} , and the point Q ₂
The coordinate values of X ₂ , Y ₂ , Z ₂ are respectively X ₁ , Y ₁ , Z ₁ and the point
By replacing the coordinate values X ₃ , Y ₃ , and Z ₃ of Q ₃ with X ₂ , Y ₂ , and Z ₂ and executing equations (2) to (5), each weaving end point A′, B′, C′ The coordinate values of can be calculated. This means that the direction of the line segment of triangle △ABC with respect to weld line _{1 2} is the direction of the line segment with respect to weld line _{2 3} , and the direction of the line segment with respect to weld line _{1 2} is set with the line segment at point Q ₂ as the axis. This is equivalent to rotating the direction by the angle formed by weld lines _{1 2} and _{2 3} . At that time, the welding line
There is no problem even if the values of distances L _{1 and} L ₂ and angles α and β corresponding to Q 2 Q ₃ are different from those values corresponding to weld line _{1 2} . Perpendicular to weld line _{1 2} ′ ₁
If the direction cosines l, m, and n cannot be equivalent to those of the weld line _{2 3} , the method for calculating each weaving end point A', B', C' for the weld line _{1 2} described above may be followed.

FIG. 2 1 shows a reference pattern of rectangles ABCD, either numerically entered or taught at another location. This reference pattern ABCD is used as a weaving pattern A′B′C′D′ in FIG.
If it can be realized for the actual welding line _{1 2} , each weaving end point A', B', C', D' can be taught once, or each weaving end point A', B', C',
If each coordinate value of D' is numerically input once and memorized, it can be used repeatedly for any welding line, and the work of teaching weaving end points can be significantly reduced. In this case, the reference pattern
Line segment from each coordinate value of vertices A, B, and C of ABCD
The length of AB L ₁ , the length of the line segment L ₂ , both of these line segments
The angle β formed by AB and AB can be easily calculated. Line segment and weld line _{1 2} to these calculated values
If you specify the angle α formed by and teach the auxiliary point P ₁ ,
A rectangle that is a reference pattern according to equations (1) to (5)
Welding lines _{1 and 2} at vertices A, B, and C of ABCD, respectively.
The weaving end points A', B', and C' can be transferred to the weaving end points A', B', and C'. However, the transfer of vertex D to weaving end point D' is slightly different because triangle ΔABC and triangle ΔACD do not necessarily form the same plane. In this case, the rectangle
For ABCD, if we redefine the angle between the line segments as β, the angle α between the line segments, the angle ζ between the line segments and the length of the line segment as L ₂ , these are the Vertices A, B,
It can be easily calculated from each coordinate value of C and D. The problem of calculating the coordinate values of the weaving end point D' is as follows:
Since the problem comes down to calculating the coordinate values of C′, the direction cosines l, m, n of the line segment ″ that have already been calculated
Using , calculate equations (3) and (4) by setting direction cosines a, b, and c of line segment '' as direction cosines h, i, and j, and calculate the results X _C ′, Y _C ′, Z _C ′ are respectively X _D ′, Y _D ′,
By substituting Z _D ′, the coordinate values X _D ′, Y _D ′, and Z _D ′ of the weaving end point D′ with respect to _the weld line ₁₂ can be calculated. Weaving can also be performed for weaving end points E', F', ... of a weaving pattern whose reference pattern is a polygon of pentagon or more by repeating the above process for weaving end points D', E', F', ... The end points E′, F′,… are the weaving end points E′, F′,… for the welding line _{1 2}
can be transferred to.

The method of calculating the weaving end points of the present invention has been described above, and next, the actual weaving motion will be described with reference to the case shown in FIG. 1 and 2. Now, the weaving movement starts from point A′ and moves toward point C′,
Assume a triangular weaving pattern that moves from point C' to point B' and then from point B' to point A'. each line segment
The travel times between A′C′, ′′, and ′′ are designated as T _AC , T _CB , and T _BA , respectively. In general, the starting point S
If the time required to travel from (X _S , Y _S , Z _S ) to the arrival point E (X _E , Y _E , Z _E ) is T, then the starting point S (X _S ,
The coordinate values X _W , Y _W , Z _W of the current point W of the weaving motion after time t has elapsed since starting from Y _S , Z _{S )} are: X _W = X _S + (X _E − X _S )・t/ T Y _W = Y _S + (Y _E − Y _S )・t/T Z _W = Z _S + (Z _E − Z _S )・t/T (6). For the line segment ′′, X _S = X _A ′, Y _S =
Y _A ′, Z _S = Z _A ′, X _E = X _C ′, Y _E = Y _C ′, Z _E = Z _C ′, and when t=T, X _W = X _E = X _C ′, Y _W = Y _E =
Y _C ′, Z _W = Z _E = Z _C ′. When the current point W of the weaving movement reaches the weaving end point E, the time t starts from zero again, and the coordinate values of the starting point S between the weaving end points are (X _S , Y _S , Z _S )
If we substitute the coordinate values of the end point E into (X _E , Y _E , Z _E ) and the required time between weaving end points into T, we get
Weaving end point C′ to B′ and weaving end point
The motion from B' to A' can be expressed by equation (6).

Meanwhile, from welding starting point Q ₁ along welding line _{1 2}
Welding starting point of the torch tip moving towards Q ₂
Welding line _{1 2} at time t′ after leaving Q ₁
If the moving components in the directions are X _P , Y _P , Z _P and the specified moving speed is V, then X _P = X ₁ + h・V・t′ Y _P = Y ₁ + i・V・t′ Z _P = Z ₁ +j・V・t′...(7).

Therefore, the coordinate values X _G , Y _G , Z _G in the orthogonal coordinate system 0-xyz that indicate the movement of the actual current point G of the tip of the welding torch attached to the robot shaft are the coordinate values X _W , Y of the weaving motion. _{X G} = _{X P +} X _{W Y G = Y P + X W Z G =} Z _{P +} Z _W ……( ₈ ) becomes.

Here, a method for processing the start and end of the weaving motion will be described. Weaving each end point A′,
When welding line _{1 2} passes through the center of gravity or the midpoint of the line segment of triangle ΔA′B′C′ connecting B′ and C′, the weaving movement starts from the welding start point Q ₁ to the weaving end point. , for example, to point A'. Originally weaving each end point
Since A', B', and C' are defined by the coordinate values of relative positions to welding line _{1 2} , X _S = Y _S = Z _S = 0, X _E
= X _A ′, Y _E = Y _A ′, Z _E = Z _A ′, and T = T ₁ , the formula
Execute (6) to (8). Here, T ₁ is a reasonable time to travel between line segments ₁ '. On the other hand, welding line
As the motion along Q ₁ Q ₂ progresses, the moving components of the welding torch tip in the _two directions of welding line ₁ X _P , Y _P , and Z _P become X ₂ ,
When positioned at Y ₂ , Z ₂ , the coordinate values of the current point X _W of the weaving motion are X _W , Y _W , and Z _W = X _W = Y _W = Z _W = 0
Not necessarily. At this time, from the current point W (X _W , Y _W , Z _W ) of the weaving motion to the point Q ₂ (X ₂ , Y ₂ , Z ₂ )
An action directed toward must be added. In this case, each coordinate value of the current point W at the moment of arrival at point Q ₂
If X _W , Y _W , and Z _W are respectively X _W ′, Y _W ′, and Z _W ′, then X _S = X _W ′, Y _S = Y _W ′, Z _S = _{Z W ′} , Z _E
= 0, specifying a reasonable time _T2 , solving equation (6), and substituting this into equation (8), the operation at this time can be realized.

In addition, the weaving motion is the weaving end point.
In the case of simple harmonic motion reciprocating between B′ and C′, from point Q ₁ ,
For example, after moving to weaving end point B', it is sufficient to repeat the movement from weaving end point B' to weaving end point C' and from weaving end point C' to weaving end point B', and this is included in the above explanation. . The same thing applies when the weaving motion moves on the polygon A′B′C′D′…, point A′→point B′→point C′→point D′→…,…point D′ →
The movement from point C′ → point B′ → point A′ will be repeated.
In addition, when moving such a polygon A′B′C′D′..., the weaving end points forming the polygon
Among A', B', C', D'..., for example, select the weaving end point by excluding the movement to and from point B', and always move from point A' to point C'. Needless to say, it is possible to specify the order of movement, such as moving from point A' to point D' and then heading to point C' instead of moving from point A' to point D'.

Note that equation (7) is a defining equation regarding linear interpolation, but
Since each end point of the weaving is calculated as a relative coordinate value with respect to the welding line, it may be a formula for circular interpolation, and the present invention can be applied to both linear motion and circular arc motion. When actually driving a robot, the points Q ₁ , Q ₂ , Q ₃ ,
Since the coordinate data of P ₁ is stored as orthogonal coordinate values, the coordinate values of the current point G at the tip of the welding torch are X _G ,
Y _G and Z _G can be used as axis drive commands, but in joint type, cylindrical coordinate type, polar coordinate type robots, etc.
First, in order to obtain orthogonal coordinate values, it is necessary to perform coordinate transformation between each drive axis and the orthogonal coordinate, and conversely, the combined coordinate values of the current point G at the tip of the welding torch are calculated, X _G , Y _G , Z _G must be converted back to each of the three basic driving axes except for the robot wrist. As an example, FIG. 3 shows a model of a five-axis articulated robot.
The pivot axis, lower arm axis (length L), and upper arm axis (length l) are controlled by rotation angles ψ and θ, respectively, and the wrist swing axis and twist axis are controlled by rotation angles γ and τ. Fourth
The figure shows the wrist area of this articulated robot and the external appearance of the installation tool. Since the point G located at distance A from the rotation center Q of the wrist swing axis and distance δ from the rotation center axis of the twist axis in Fig. 3 is the control point to be taught, its coordinate value on the orthogonal coordinate axis 0-xyz is X _G (L・cosθ+l・cos+A・sinγ+δ・cos
τ・cosγ)・cosψ−δ・sinτ・sinψ X _G (L・cosθ+l・cos+A・sinγ+δ・cos
τ・cosγ)・cosψ−δ・sinτ・sinψ Y _G = (L・cosθ+l・cos+A・sinγ+δ・cosτ・
cosγ)・sinψ−δ・sinτ・sinψ X _G (L・cosθ+l・cos+A・sinγ+δ・cos
τ・cosγ)・cosψ−δ・sinτ・sinψ Y _G = (L・cosθ+l・cos+A・sinγ+δ・cosτ・
cosγ)・sinψ−δ・sinτ・sinψ Z _G =L・sinθ+l・sin−A・cosγ+δcosτ・sin
γ...(9) becomes.

Here, the current values γ _G and τ _G of the rotation angles γ and τ of the wrist tilt axis are γ _G = γ ₁ + (γ ₂ − γ ₁ )・V・t ₁ /D ₁ τ _G = τ ₁ + (τ ₂ −τ ₁ )・V・t ₁ /D ₁ ...(10). Here, the wrist swing axis moves relatively starting from the rotation angle γ ₁ , τ ₁ at the welding start point Q ₁ within the time required for the welding line _{1 2} to advance, and changes to the rotation angle γ at the point Q ₂ . ₂ , τ ₂ shall be reached. D ₁ is welding point _{1 2}
is the distance. For example, the command value on the multi-joint axis of the momentary current point G (X _G , Y _G , Z _G , γ _G , τ _G ) of the tip of the welding torch is obtained by inversely converting the equation (9) that has already been found. The following equation ψ _G = h ₁ (X _G , Y _G , Z _G , γ _G , τ _G ) θ _G = h ₂ (X _G , Y _G , Z _G , γ _G , τ _G ) _G = h ₃ ( X _G , Y _G , Z _G , γ _G , τ _G ) ...(10) is found, and ψ _G , θ _G , _G , γ _G , and τ _G become robot drive commands.

FIG. 5 is a block diagram of one embodiment of a welding robot implementing the method of the present invention. teaching box 2
0, the coordinate values of points Q ₁ , Q ₂ , Q ₃ and auxiliary point P ₁ on the welding line are taught. Distances L ₁ , L ₂ ,
Input data such as angles α and β, moving speed V, etc.
These taught and input points Q ₁ , Q ₂ , Q ₃ , position data of auxiliary point P ₁ , distances L ₁ , L ₂ , angles α, β,
The data of the moving speed V is stored in the teaching data storage device 40. The overall control block 10 accepts the operator's operations on the operation panel 30 and centralizes the overall control as a playback mode. The trajectory controller 50 is a circuit for implementing the weaving pattern teaching method of the present invention. Reference numerals 70 to 74 indicate shaft drive control units provided for each axis.

FIG. 6 is a block diagram showing details of the trajectory controller 50. First, the teaching point data stored in the teaching data storage device 40 is set in the coordinate converter 51, and is converted into orthogonal coordinates according to equation (9). Coordinate-converted teaching point data X ₁ , Y ₁ , Z ₁ ,
γ ₁ , τ ₁ are connected to the latch circuit 52, X ₂ , Y ₂ , Z ₂ , γ ₂ ,
τ ₂ is set in the latch circuit 53, and X ₁ ', Y ₁ ', Z ₁ ' are set in the latch circuit 54 by the control signal S ₅ output from the control signal generator 60, respectively. distance L ₁ ,
L ₂ , angles α and β are the weaving position generator 55
Then, the predetermined travel times T _AC , T _CB , T _BA , T ₁ , T ₂ are stored in the weaving generator 56, and the travel speed V is stored in the current progress value generator 57 in the teaching data storage device 40.
is output from and set. The weaving position generator 55 outputs the coordinate values X ₁ , Y ₁ , Z ₁ , γ ₁ , τ ₁ , latched by the latch circuits 52 , 53 , 54 , respectively.
The coordinate values of each weaving end point A′, B′, and C′ are calculated from X ₂ , Y ₂ , Z ₂ , γ ₂ , τ ₂ , X ₁ , Y ₁ , and Z ₁ .

FIG. 7 is a block diagram showing details of the weaving position generator 55. Directional cosine generator 101
calculates the direction cosine h, i, j of the weld line _{1 2} and the distance D ₁ of the weld line 1 from the coordinate values X ₁ , Y ₁ , Z ₁ and X ₂ , Y ₂ , _{Z 2} . Similarly, direction cosine generator 1
02 is the coordinate value X ₁ , Y ₁ , Z ₁ and X ₁ ′, Y ₁ ′,
Calculate the direction cosines l′, m′, and n′ of line segment _{1 1} from Z ₁ ′. The first direction generator 103 is the direction cosine generator 10
Direction cosine h, i, calculated at 1,102, respectively
Execute equation (1) based on j, l′, m′, n′ and find the perpendicular line
Calculate the direction cosines l, m, and n of A′P ₁ . The weaving end point B' calculator 104 calculates the direction cosines _l , m,
Based on the input distance L ₁ as n, the coordinate values of l・L ₁ , m, L ₁ , n・L ₁ on the right side of equation (2), that is, the weaving end point B′, are X _B ′, Y _B ′, Z _B ′ Calculate. The second direction generator 105 includes direction cosine generators 101 and 10.
Direction cosine (h, i, j), (l′, m′,
n'), l·L ₁ calculated by the first direction generator 103,
Execute equation (3) from m・L ₁ , n・L ₁ and the input angles α and β, and calculate the direction cosines a, b, c of the line segment ''
Calculate. Weaving end point C′ operator 106
is the equation (4) from the direction cosines a, b, and c calculated by the second direction generator 105 and the input distance _L2 .
L ₂ ·a, L ₂ ·b, L ₂ ·c, that is, the coordinate values X _C ', Y _C ', and Z _C ' of the weaving end point C' are calculated. The weaving end point A' calculator 107 calculates equation (5) from the outputs X _B ′, Y _B ′, Z _B ′ of the weaving end point B′ calculator 104 and the outputs Xc′, Z _C ′ of the weaving end point C′ calculator 106. Execute the weaving end points A′, B′,
Welding line _{1 2} The center of gravity of the triangle ΔA′B′C′ connecting C
Calculate the coordinate values (X _A ′, Y _A ′, Z _A ′) of the weaving end point A′ when the weaving passes through. The overall control block 10 causes the control signal generator 60 of the trajectory controller 50 to perform this calculation, that is, to control the denominator of equation (5). The multiplexer 108 is connected to the control signal generator 6
According to the selection control signal S ₁ from 0, the outputs X _B ′, Y _B ′, Z _B ′ of the weaving end point B′ calculator 104, the outputs X _C ′, Y _C ′,
Z _C ′, a set of data consisting of zero, and the outputs of the weaving end point A′ calculator 107 X _A ′, Y _A ′,
Z _A ′, output of weaving end point A′ calculator 107
X _A ′, Y _A ′, Z _A ′ plus the outputs of the weaving end point B′ calculator 104 X _B ′, Y _B ′, Z _B ′, the outputs of the weaving end point A′ calculator 107 X _A ′, Y _A ′, Z _A ′ plus weaving end point C′ output of the calculator 106 X _C ′,
Data of either one of a set of data consisting of Y _C ′ and Z _C ′ is input and output.

FIG. 8 is a block diagram showing details of the weaving generator 56 of FIG. 6. multiplexer 20
1 generates a control signal under the instruction of the overall control block 10 to determine the required time T _AC , T _CB , T _BA , T ₁ , T ₂ between each weaving end point A', B', C'. The selection control signal _S2 outputted from the device 60 selects and outputs the selected signal. The multiplexer 202 controls the starting points X _S , Y _S , Z _S and the ending points X _E ,
Y _E and Z _E are selected and output by the selection control signal S ₃ output from the control signal generator 60 under the direction of the overall control block 10 . Now, assuming that the weaving motion is directed from point Q ₁ to weaving end point A', multiplexers 201 and 202 are set to the specified time T = T ₁ and the starting point X _S = 0, Y _S = 0, respectively.
The signals with Z _S = 0, end point X _E = X _A ′, Y _E = Y _A ′, and Z _E = Z _A ′ are selected and output. The weaving current value generator 203 receives a signal t indicating the passage of time from the start point from the control signal generator 60, a specified time T output from the multiplexers 201 and 202, and coordinate values of the start point and end point of the weaving motion. _XS , _YS ,
Equation (6) is executed based on Z _S , X _E , Y _E , and Z _E to calculate the current values of weaving motion X _W , Y _W , and Z _W . When the signal t indicating the passage of time reaches the specified time T, the comparator 204 outputs the signal S ₄ to the control signal generator 60, and the control signal generator 60 initializes the signal t with this signal S ₄ and also outputs the signal S 4 to the multiplexer. 201,
202 is specified time T= by selection control signals S ₂ and S ₃
Select T ₁ , starting point X _S =X _A ′, Y _S =Y _A ′, Z _S =Z _A ′, ending point X _E =X _C ′, Z _E =Z _C ′. The control signal generator 60 sequentially switches the start points X _S , Y _S , Z _S and the end points X _E , Y _E , Z _E of the weaving motion at specified time intervals T using the selection control signals S ₂ and S ₃ . Latch circuit 2
05 is provided to store the current values of weaving motion X _W ', Y _W ', Z _W ' at the moment when _the welding line ₁₂ has finished advancing, and to set them at point _Q2 .

The progress current value generator 57 in FIG. Equation (7) is executed from the direction cosines h, i, and j, and the coordinate values X ₁ , Y ₁ , and Z ₁ latched in the latch circuit 52, and the coordinate value X of the moving component in _two directions of the welding line ₁ at the tip of the torch is _P ,
Calculate Y _P and Z _P. This calculated coordinate value X _P ,
When Y _P and Z _P respectively reach X _P = X ₂ , Y _P = Y ₂ , and Z _P = Z ₂ , that is, when the torch tip reaches point Q ₂ , a signal T ₀ is output to the control signal generator 60 to control signal generator 60
As a result, the latch circuit 205 of the weaving generator 56 stores the current values of the weaving motion X _W ′, Y _W ′, Z _W ′, and the current point G changes to the point Q ₂
Sequence control is performed to move toward . Although the progressing current value generator 57 is for linear interpolation in this embodiment, it may be for circular interpolation.
The coordinate value X _W which is the output of the weaving generator 56,
Y _W , Z _W and the coordinate values X _P , Y _P , Z _P which are the outputs of the progress current value generator 57 are added by an adder, and the coordinate values X _G , Y _G , Z _G which are the added values are the inverse coordinates. input to converter 59; On the other hand, the wrist current value generator 58 is at the point Q ₁ ,
Wrist coordinate values γ ₁ , τ ₁ and γ ₂ at Q ₂ , respectively,
τ ₂ , the output D ₁ of the weaving position generator 55, and the input velocity V, execute equation (10) to calculate the current values γ _G and τ _G of the wrist swing axis, and convert these to the inverse coordinate converter 59. Output to. The inverse coordinate converter 59 converts these input values γ _G , τ _G and coordinate values X _G , Y _G , Z _G into equation (11)
Execute and calculate the current value ψ _G of each drive axis ψ, θ,
Calculate θ _G and _G.

Now, in Fig. 1, when the operation for welding line _{1 2} is completed, if the direction cosines l, m, and n are valid for the subsequent welding line _{2 3} , then the point
By latching the data of the direction cosines l, m, and n (not shown) at the moment _Q2 is reached, this becomes _the direction cosine for the weld line ₂₃ . and,
The point Q ₂ is input to the latch circuit 52 as the coordinate values X ₁ , Y ₁ , Z _{1 .}
If the coordinate values X ₂ , Y ₂ , Z ₂ of the point Q 3 are latched to _{the latch circuit 53 as the coordinate values X 2 , Y 2 , Z 2 of the point Q 3 ,} the weld line ₂ The coordinate values of each weaving end point A', B', and C' for ₃ can be calculated.

Again, β,
The distances L ₁ and L ₂ are calculated by using two direction cosine generators and some arithmetic units. By substituting these calculated values into the weaving position generator 55, the second
It is easily inferred that this can be realized as the weaving end points A', B', and C' in FIG. Similarly, distance L ₂ =, angle β = ∠BAD, α = ∠CAD, γ
=∠BAC etc. can also be calculated. These values are input to the weaving position generator 55. The outputs h, i, and j of the direction cosine generator 101 are switched to the stored direction cosines a, b, and c of the line segment by a changeover switch (not shown), and are input to the second direction generator 105. The second direction generator 105 is a line segment
From the direction cosines l, m, n of A'B' and the direction cosines a, b, c of line segment '', the direction cosines a, b of line segment '',
c is calculated, and the results X _D ″, Y _D ″, and Z _D ″ are sent to the weaving end point C′ calculator 106 as X _C ′, Y _C ′, and
It is output as Z _C ′.

Note that the various arithmetic units used in the trajectory controller 50, such as an adder/subtractor, a multiplier/divider, a trigonometric function unit, and an inverse trigonometric function generator, are versatile. 9th
The figure shows a circuit diagram of direction cosine generators 101 and 102 as an example of these arithmetic units. 301,
302 and 303 are multipliers, 304 is a square rooter, 3
05, 306, 307 are dividers, 308, 30
9 and 310 are subtracters, and 311 and 312 are adders.

The explanation will return to FIG. 6, but the current driving values of each axis τ _G , γ _G , θ _G , ψ _G , _G calculated by the inverse coordinate converter 59 are latched for each signal Δt generated by the control signal generator 60. It is stored in the circuit 61 and becomes the previous value. The difference between the current drive value of each axis and the previous value becomes the actual drive command for each axis of the robot within time Δt. The signal Δt is the signal t,
Along with Σt, three counters in the control signal generator 60 are counted based on a reference clock.

FIG. 10 is a block diagram of drive shaft control for one axis. The axis drive command of the trajectory controller 50 (FIG. 5) becomes each axis command pulse uniformly delivered by the command circuit 401 within a time period Δt. The difference between each axis command pulse and the pulse from the pulse generator PG is output from the deviation counter 402, and is D/A converted by the D/A converter 403. The motor M is rotationally driven by the servo amplifier 404 in the direction in which the output of the deviation counter 402 becomes zero, but when the number of pulses up to point Q ₂ has been delivered to the command circuit 402 and there is no subsequent command pulse. The output of the deviation counter 402 becomes zero and the motor M stops. The above operations are performed simultaneously on each axis.

The present invention teaches a single auxiliary point at any position on or near the workpiece, and allows robot space at each weaving end point of the weaving pattern simply by numerically specifying the angle, distance, etc. that indicates the positional relationship between the weaving pattern and the welding line. Coordinates in the coordinate system are automatically calculated, and there is no need to teach the weaving end point for each welding line as in the conventional method, making the teaching work of the soft weaving method extremely efficient. In addition, there is no need to teach auxiliary points for each welding line, and weaving end points can be continued, and once a weaving pattern has been set, it can be registered and reproduced for any welding line. be able to. Furthermore, the present invention
Workability is significantly improved by overcoming the conventional location restriction in which each end point of the weaving can only be taught near the welding line and the difficulty in accurately teaching the amplitude and direction of the weaving.

[Brief explanation of drawings]

Fig. 1 is a diagram for explaining the principle of the present invention when performing weaving motion using triangle ΔABC as a reference pattern, Fig. 2 is an explanatory diagram of the present invention when performing weaving motion using rectangle ABCD as a reference pattern, and Fig. 3 4 is a perspective view of a five-axis articulated robot to which the method of the present invention is applied, FIG. 4 is a plan view showing the welding torch, wrist swing axis, and twist axis, and FIG. 5 is a perspective view of a five-axis articulated robot to which the method of the present invention is applied. Third
6 is a block diagram of the trajectory controller 50, FIG. 7 is a block diagram of the weaving position generator 55, FIG. 8 is a block diagram of the weaving generator 56, and FIG. 9 is a direction cosine diagram. A block diagram of the generators 101 and 102, and FIG. 10 is a drive shaft control block diagram for one axis. 51...Coordinate converter, 52, 53, 54, 61
... Latch circuit, 55 ... Weaving position generator, 56 ... Weaving generator, 57 ... Progress current value generator, 58 ... Wrist current value generator, 59
... Inverse coordinate transformer, 60 ... Control signal generator.

Claims (1)

[Claims] 1. In a teaching playback welding robot that teaches welding lines using the PTP method, a reference pattern of a predetermined triangle △ABC is set in advance, and any arbitrary point on or near a workpiece set in a jig is set in advance. Any line segment of the taught weld line at the position
Q _o Teach an auxiliary point P _o corresponding to Q _o+1 , and on the line segment _{o o+1} , find the angle that the auxiliary line _{o o} connecting to the auxiliary point P _o makes with the line segment _{o o+1.} Set a point S _o so that the angle ζ is a predetermined angle, and set the apex A' of a triangle △A'B'C' that is congruent with the reference pattern at the point S _o ,
The vertex B' is set on the auxiliary line _{o o} , the apex C' is set so that the angle between the line segment '' and the line segment _{o o+1} is a predetermined angle α, and the triangle △A'B' A weaving pattern teaching method for a welding robot in which a triangle △A″B″C″ in which C′ is moved by a certain vector amount is a weaving pattern corresponding to the line segment _{o o+1} . 2 Other than the taught welding line A patent in which a line segment obtained by translating the reference line _{r r} corresponding to the line segment _{r r +1} to an arbitrary point on the line segment o _o+ 1 is set as the reference line corresponding to the line segment _{o o+1} A method for teaching a weaving pattern in a welding robot according to claim 1. 3. In a teaching playback welding robot that teaches welding lines using the PTP method, a reference pattern of a predetermined polygon □ABCD... that is more than a quadrangle is set in robot space coordinates. Any line segment of the taught welding line can be set in advance in the system and placed at any position on or near the workpiece set in the jig.
Q _o Q _o+1 is taught an auxiliary point P _o , and the angle between the auxiliary line o o connecting the auxiliary point _{P o} and _the line segment _{o o+1} on the line segment _{o o+1} is Determine a point S _o so that it forms a predetermined angle ζ, and draw the polygon □
The apex A' of the triangle △A'B'C' formed by any three vertices of the polygon □A'B'C'D'... which is congruent with ABCD... is set at the point S _o , and the apex B' is set at the auxiliary line _{o o} defined above, line segment
The vertex C' is determined so that the angle between A'C' and the line segment _{o o+1} is a predetermined angle α, and the polygon □
Other vertices D′,… of A′B′C′D′… are the triangle △
The polygon □A″B″C″D″… which is determined based on A′B′C′ and the obtained polygon □A′B′C′D′… is moved by a certain vector amount is the line segment _o
The weaving pattern corresponds to Q _o+1 ,
A weaving pattern teaching method for a welding robot.