JPH0410567B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an interlocking control method for a rotary table of a positioner which is rotationally driven independently and a teach/reproduce type PTP robot whose drive is controlled by a control system separate from the rotary table. be.

Industrial robots are generally constructed with multiple degrees of freedom, and these degrees of freedom allow them to give arbitrary positions and postures to welding torches, paint guns, and other tools attached to the tip of their wrists. In general, there is an optimal posture for tools, etc. depending on the specificity of each task.

For example, when it comes to welding, the best position is to work with the welding torch pointing downwards, and the next best position is horizontal fillet welding. And since the posture of such tools is not the relative angle between the workpiece or other workpiece and the welding torch or other tool, but the angle with respect to the ground, it is difficult to imagine how a robot could theoretically have a sufficient degree of freedom. However, it is not possible to assume all possible postures depending on the work being done.

Therefore, a robot peripheral device called a positioner is required to position the object to be worked on (hereinafter referred to as a work) at an appropriate angular position where the robot can easily work on it.

A typical way to use such a positioner is to fix a workpiece on the rotary table of the positioner, rotate the rotary table to position the workpiece, and then the robot performs work such as welding on the workpiece. When work such as welding on a certain part that is convenient for controlling the robot's posture is completed, the robot retreats, and then the positioner positions the workpiece at another angle, and the robot performs the welding work again. This action is repeated.

For example, when performing fillet welding 2 on the bottom side of a box-shaped workpiece 1 shown in Fig. 1, it is most natural for a robot to perform welding from the top of the workpiece 1 along a horizontal welding line. As shown in Figure a, fillet welding is first performed along the horizontal welding line 2 while the workpiece 1 is held vertically, and then fillet welding is performed along the horizontal welding line 2.
It is common to rotate the weld by 90 degrees and hold it laterally as shown in FIG. 1b, and weld along the weld line 3 perpendicular to the weld line 2.

The positioner rotates the workpiece 1 and holds it in that position.

As mentioned above, when the work trajectory (welding lines 2 and 3 in Figure 1) consists of a straight line connection, it is quite effective to repeat positioning using the positioner as described above, but if the workpiece is When the working trajectory of a welding line or the like is curved, such as a cylindrical workpiece 4 such as a silk hat type shown in Figure 2, if the number of workpiece positionings is small, smooth posture control using interpolation calculations is not possible. On the other hand, if the number of positions is large, the number of bead joints will increase, which can easily cause welding defects. There was a desire for a control direction that would allow welding to be carried out continuously while the welding section 7 was kept substantially fixed.

Such continuous control is relatively simple for CP control type robots that teach multiple points along the work trajectory.For example, there is a method described in Japanese Patent Application No. 57-3174. For PTP-controlled robots that teach only the above representative points and obtain intermediate points through interpolation calculations, a method called simple interlocking is available to some extent.

Simply put, this simple interlocking control is a method in which the positioner is operated at a low speed at a set speed, while the robot side is fixed and an arc is generated. To weld the workpiece 4, first, the rotation axis of the rotary table of the positioner is aligned with the center of the workpiece, and the distance (radius) r to the welding line 9 is determined. If you want to weld the welding line 9 at a circumferential speed v, set the rotation speed N of the rotary table to N (rpm) = v/
(2π×r): Number of rotations N for the positioner
This is done in a way that you can enter.

However, with this simple interlocking, as mentioned above, the welding line must be in a perfect circular arc shape, and the center axis of the work must be set to match the rotational axis of the positioner, and the welding line must be an arbitrary curve. It cannot be used when the object is a combination of circular arcs and straight lines, or where it is difficult to align the rotation axis of the positioner with the center line of the workpiece.

This situation is caused not only by the relationship between the welding robot and the positioner that holds the workpiece, but also by the relationship between the painting robot, deburring robot, and other manipulators, as well as the relationship between the welding robot and the positioner that holds the workpiece. This is a problem that occurs equally with rotary tables for holding objects.

In view of the above-mentioned circumstances, the present invention can be applied even when the axis of the rotary table and the axis of the workpiece are eccentric, or when the work trajectory of the robot is an arbitrary curve or a combination of a curve and a straight line. It is an object of the present invention to provide a control method that can automatically detect the radius of rotation, that is, the distance (radius) from the center of the rotary table to the working position, and can interlock a robot and a positioner, which can be equally applied. The gist is that, in a method for interlocking control of a teach-and-reproduce PTP robot and a positioner combined with the robot, a normal vector in the same direction as the rotation axis of the rotary table of the positioner is set at an arbitrary point on the rotation axis. The two center points are taught or numerically inputted to the robot, or data of an arbitrary teaching point on the rotary table in the coordinate system of the robot and the arbitrary teaching point when the rotary table is rotated. a step of determining by calculating based on a plurality of teaching point data after the position of the corresponding point has changed; a step of teaching the robot the position coordinates of an arbitrary measurement point fixed on the rotary table; The process of calculating the direction vector between the measurement point and the center point using an arbitrary center point on the axis and each position coordinate of the measurement point, and calculating the absolute value of the cross product of the normal vector and the direction vector of the normal vector. a step of detecting a radius of rotation, which includes a step of dividing by an absolute value; a step of determining a movement angle of a tip of a tool provided on the robot with respect to the rotation axis of the rotary table; and a step of determining a rotation angle of the rotation axis of the rotary table. The rotation radius detected in the rotation radius detection step, the movement angle of the tool tip with respect to the rotation axis, the rotation angle of the rotation axis, and the rotation angle of the tool tip during interlocking operation in which data is input as appropriate. The point is that the controlled movement speed of the robot and the rotation speed of the rotary table are determined from the set movement speed on the rotary table.

Next, embodiments embodying the present invention will be described with reference to the accompanying drawings starting with FIG. 4 to provide an understanding of the present invention. Here, FIG. 4 is a perspective view showing an example of the arrangement of a rotary positioner and a welding robot to which the interlocking control method of the present invention can be applied, and FIG. 5 is a rotation radius in the control method according to the present invention. This is a flowchart showing the procedure of detection work, and the outline of the control method according to the present invention will be first explained using these figures.

An example of the positioner will first be explained using FIG.

In Figure 4, positioner PS is base 10.
Support frames 10a and 10b provided vertically above
supports a U-shaped support frame 13 rotatably around a horizontal axis α in the horizontal direction, and the support frame 13 has a rotation axis β perpendicular to the horizontal axis α at its center. It holds a rotary table 14 that can be rotated around. Reference numeral 11 denotes a drive source for the support frame 13, and a drive source for the rotary table 14 is located on the back side of the rotary table 14 and is not shown in the figure.

Further, FIG. 4 shows a welding robot 7 as an example of a robot, and a welding torch T is attached to the tip of a horizontal arm 7a of this welding robot 7.

Therefore, the rotational position and direction of the workpiece mounted on the rotary table 14 is controlled by two degrees of freedom: rotation around the horizontal axis α and rotation around the rotation axis β.

Next, a method for determining the distance from an arbitrary point on the rotary table 14 of the positioner PS to the rotation axis β, that is, the radius of rotation at the arbitrary position using the robot 7 described above, is shown in FIG. This will be explained using the flowchart shown above and the block diagram shown in FIG.

As shown in FIG. 5, this method begins with the step (step a) of determining the normal vector on the rotation axis β of the rotary table 14. There are three possible methods for determining this normal vector: (1) data input method, (2) method using a jig, and (3) method in conjunction with a rotary table, each of which will be explained in detail later. explain.

When the normal vector of the rotary table 14 is determined in step a, a workpiece is set on the rotary table 14, and the position coordinates of an arbitrary measurement point (for example, a point on the welding line) on the workpiece are taught to the robot 7. (Step b).

The robot 7 is controlled by a microcomputer 15 as shown in FIG. The position command signal is sent to the motor M that drives the robot 7 via the motor M.

The microcomputer 15 is a read-only memory (not shown) that stores programs according to the flowcharts shown in FIGS. 5, 10, etc.
It is composed of a ROM, a storage device RAM that temporarily stores various data, a central processing unit CPU (not shown) that executes the contents of the above program, and an input/output interface circuit (not shown). ing.

The motor M rotates in a predetermined direction upon receiving the position command signal, and drives an arm having a welding torch T or the like at its tip.

The position of the arm thus driven is detected by a position detector 19 consisting of a rotary encoder, resolver, potentiometer, etc. attached to the joint of the arm, and the position is detected by the microcomputer 1.
By feeding back the arm position information to 5,
Positioning is automatically controlled.

The robot 7 used in this method is a PTP-controlled robot that drives the arm as described above, moves the welding torch T at the tip of the arm along the work trajectory, and locates representative points on the work trajectory. When the arm is reached, the arm is stopped, and the position information of the arm at that position is detected by the position detector 19, and is imported into the microcomputer 15 and stored in the storage device.
It is stored sequentially in RAM, and when the robot is regenerated, the position coordinates stored in the storage device RAM are retrieved each time, and the space between each measurement point is divided into multiple points and interpolated, and this interpolated data is Based on this, the robot 7 is continuously driven.

Therefore, as described above, in steps a and b, the position coordinates of the normal vector of the rotary table 14 in the coordinate system specific to the robot 7 and the position coordinates of an arbitrary measurement point on the workpiece are stored in the storage RAM. stored within.

Based on the normal vector and the position coordinates of the measurement point thus obtained, the microcomputer 15 generates a vector (hereinafter a direction vector) on a straight line connecting an arbitrary point on the normal vector (hereinafter referred to as the center point) and the measurement point. ) is determined (step c).

Next, the microcomputer calculates the cross product of the normal vector and the direction vector (step d), and further divides the absolute value of the cross product of the normal vector and the direction vector by the absolute value of the normal vector to obtain ( Step e): Obtain the distance from the rotation axis β of the rotary table 14 to the measurement point, that is, obtain the rotation radius of the measurement point on the workpiece when the rotation table 14 is rotated around the rotation axis β, and calculate the rotation radius related to this rotation radius. Data is stored in the storage RAM.

In the actual teaching operation, the procedure for determining the normal vector of the rotary table shown in step a only needs to be performed once at the beginning, and then steps b to e are repeated sequentially for a large number of measurement points. The radius of rotation for each measurement point is sequentially stored in the storage device RAM, and during the playback operation, each radius of rotation is sequentially retrieved and interpolated calculations are performed to obtain the radius of the point between the measurement points. The robot arm is moved continuously along the work trajectory.

Next, the procedures from a to e shown in FIG. 5 will be explained in more detail.

As mentioned above, there are three methods for determining the normal vector of the rotary table, and these will be explained first.

"Data input method" This is the position of center points A and B on the rotation axis β in the coordinate system on the robot side when the horizontal axis α of the rotary table 14 is fixed at a certain angle, as shown in Fig. 7. Coordinates (Xa, Ya, Za) and (X _b ,
In this method, Y _b , Z _b ) are measured using a commonly used scale, etc., and the values are input into the storage device RAM from the operation panel 16 on the robot side using a numeric keypad or the like.

A teaching method in which the coordinate data of such a normal vector AB is directly introduced into the robot 7 is designed such that if the positional relationship between the robot 7 and the positioner PS is fixed, only one such normal vector This is convenient because it can be stored in read-only memory ROM etc. from the beginning, but in general robots, positioner PS and robot 7
The positional relationship with Detecting the position coordinates of vector AB is time-consuming and cannot be expected to be accurate, so this is disadvantageous.

"Method using a jig" This method is based on an insertion hole for inserting a jig 20 as shown in FIG. 8 on the axis of the rotary table 14 of the positioner PS shown in FIG. 21 is drilled in advance, and a jig 20 is inserted into this insertion hole 21.
is inserted to teach the robot 7 the position of the center line mark 22 carved on the center axis of the jig 20 (see FIG. 8b). That is, since the jig 20 is inserted into an insertion hole 21 drilled coaxially with the rotation axis β, a center line mark 22 engraved at its center
coincides with the rotation axis β, and even if the rotary table 14 is rotated, the center line mark 22 always exists on the rotation axis β.In teaching, the arm of the robot 7 is guided to the direction of the torch T. The tip (arc generation point) is guided to arbitrary positions (center points) A and B on the center line mark 22, and the robot's position coordinates A (Xa, Ya, Za ),
B (X _b , Y _b , Z _b ) is stored in the storage device RAM.

"Method of interlocking with a rotary table" In this method, as shown in Figure 10, the horizontal axis α of the positioner PS is held at a certain angle (step f), and the next operation is carried out. .

First, as shown in FIG. 9, the robot 7 is guided by an inching operation using the remote control operation panel 16 so that the tip of the torch T is aligned with an arbitrary teaching point _M1 on the rotary table 14.
When the tip of the torch T matches the teaching point _M1 , press the storage button to store the position coordinates (X ₁ , Y ₁ , Z ₁ ) of the teaching point M ₁ in the storage device RAM in the control circuit on the robot side. (Step g). The coordinate system of the position stored at this time is a position coordinate in a coordinate system specific to the robot 7 side with the robot 7 as a reference, for example, an X, Y, Z orthogonal coordinate system with the origin at a predetermined origin position of the robot 7. be. The teaching point M ₁ obtained in this way is called the first teaching point.

Next, a rotation command signal is given to the control system of the positioner PS to rotate the rotation axis β by an appropriate amount (θ ₁ ) (step h), and the first teaching point M ₁ is moved from the position of M ₂ around the rotation axis β. position, move the robot,
Position coordinates of teaching point M ₂ (X ₂ , Y ₂ , Z ₂ )
is stored in the storage device RAM.

The rotation angle θ ₁ of the above positioner is the positioner PS
It is read by a position detector 23 such as an encoder or resolver attached to the side rotation axis β (see FIG. 6), and is sent to the microcomputer 15 and stored in the storage device RAM (step i).

Furthermore, a rotation signal is given to the positioner PS side to rotate the rotary table 14 again, and the position coordinates (X ₃ , Y ₃ , Z ₃ ) of point M ₃ , which is the position to which point M ₂ has moved due to this rotation, are determined by the robot. 7 is stored in the storage device RAM (step j).

Next, distances ₁ and ₂ are determined from the teaching points _M1 and _M2 (step k).

₁ , ₂ = √( ₂ − ₁ ) ² + ( ₂
−Y ₁ ) ² +(Z ₂ −Z ₁ ) ² (1) Here, as is clear from FIG. 9 (Step 1), Rsinθ ₁ /2=M ₁ , M ₂ /2 (2) holds true.

Since ₁ , ₂ and θ ₁ have been found using the above equations (1) and (2), the radius R of measurement point M ₁ centered on the β axis is R=M ₁ M ₂ /2/sinθ ₁ /2... (3).

Next, since the distances of M ₁ to _{M 3} from the rotation axis β are all R, (X ₁ − Xa) ² + (Y ₁ − Ya) ² + (Z _{1 −} Za) ² = R ₂ (X ₂ − Xa) ² + (Y ₂ -Ya) ² + (Z ₂ -Za) ² = R ₂ (X ₃ - Xa) ² + (Y ₃ - Ya) ² + (Z ₃ - Za) ² = R ₂
…(4) holds true.

The three variables Xa, Ya, and Za in this equation (4) can be found by combining equations (4). However, the calculation method is omitted. Here, (Xa, Ya, Za) are in the coordinate system specific to the robot side of the center point A, which is on the rotation axis β and on the plane where points M ₁ , M ₂ , and M ₃ exist. It is the location coordinates.

In addition, two vectors M ₂ M ₁ ―→, M ₂ M ₃ ―→ (step m), which are formed by the above measurement points M _{1 ,} M _{2 ,} and M ₃ ,
If the cross product of is a vector M ₂ P-→, then the vector M ₂ P is perpendicular to the plane N that includes the three teaching points M ₁ to M ₃ , so it becomes a vector parallel to the vector representing the rotation axis β. Then, the vector with point A as the base point is
Assuming that a vector having the same component as M ₂ P is AB (step n), this represents a normal vector existing on the rotation center of the rotary table 14 that coincides with the rotation axis β. That is, AB=M ₂ P=M ₂ M ₁ ×M ₂ M ₃ = {(Y ₁ − Y ₂ ) (Z ₃ − Z ₂ ) − (Z ₁ − Z ₂ ) (Y ₃ − _{Y 2} ), (Z ₁ −Z ₂ )(X ₃ −X ₂ )−(X ₁ −X ₂ )(Z ₃ −Z ₂ ), (X ₁ −X ₂ )(Y ₃ −Y ₂ )−(Y ₁ −Y ₂ ) (X ₃ −X ₂ ) …(5) Thus, the normal vector AB of the rotary table 14 is
is obtained.

However, in the procedure for calculating the three normal vectors described above, the position of the normal line of the control device is memorized because storing the position of the normal line must be distinguished from teaching the general work trajectory. This is carried out in a state where the mode has been switched, and a storage area in the storage device RAM is secured that is separate from the storage on the general teaching trajectory.

Once the normal vector AB―→ is obtained by any of the above-mentioned methods (1) data input method, (2) method using a jig, or (3) interlocking method with a rotary table, the next step is to The procedure moves on to step b shown in FIG.

That is, the workpiece is placed on the rotary table 14 as described above, and the work trajectory such as the welding line is taught. 1st
Figure 1 shows a plan view of the workpiece. The workpiece 24 is a silk hat-shaped workpiece similar to that shown in FIG. 2, and a case will be described in which fillet welding is performed on the circumference of the workpiece.

First, as shown in step b of FIG. 5, the positional coordinates of an arbitrary measurement point C on the welding line in the coordinate system on the robot side are taught by guiding the tip of the welding torch of the robot to that point. Note that the center O of the workpiece 24 is the normal vector AB on the rotation axis β obtained using the above method.
The case where the center is eccentric from the center will be explained. Here, as shown in Figure 8c, the absolute value of the cross product of the normal vector AB-→ and the vector AC-→ connecting the center point A and the measurement point C is the value of the cross product of the parallelogram with both vectors as two sides. It is the area. The cross product of both vectors is the normal vector
The absolute value of AB-→, that is, the height R when divided by the length of side AB,
That is, the distance between the normal vector AB-→ and the measurement point C is determined. This holds true for any normal vector AB--> (steps c to e).

The above method is calculated in the microcomputer 15 as follows.

Since the normal vector AB-→ has been obtained by the above procedure, its coordinates (Xa, Ya, Za), (X _b , Y _b ,
Z _b ) is already known, and the coordinates (Xc, Yc, Zc) of the measurement point C mentioned above are also known, so from these coordinates AB - → = (X _B - X _A , Y _B - Y _A , Z _B −Z _A ) AC−→=(X _C −X _A , Y _C −Y _A , Z _C −Z _A ) …(6) The normal vector AB−→ and the direction vector AC−→ The cross product with is AB―→×AC―→={(Y _B −Y _A )(Z _C −Z _A )
−(Z _B −Z _A )(Y _C −Y _A ), (Z _B −Z _A )(X _C −X _A )−(X _B −X _A )(Z _C −Z _A ) (X _B −X _A )(Y _C −Y _A )−(Y _B −Y _A )(X _C −X _A )} …(7) and its absolute value is |AB−→×AC−→|=√{(Y _B −Y _A )(Z _C
−Z _A )−(Z _B −Z _A )(Y _C −Y _A )} ² |AB−→×AC−→|=√{(Y _B −Y _A )(Z _C
−Z _A )−(Z _B −Z _A )(Y _C −Y _A )} ² √+{(Z _B −Z _A )(X _C −X _A )−(X _B −X _A )(Z _C − Z _A )}
² ｜AB―→×AC―→｜=√{(Y _B −Y _A ) (Z _C
−Z _A )−(Z _B −Z _A )(Y _C −Y _A )} ² √+{(Z _B −Z _A )(X _C −X _A )−(X _B −X _A )(Z _C − Z _A )}
² + {(X _B −X _A )(Y _C −Y _A )−(Y _B −Y _A )(X _C −X _A )} ²
...(8) Also, the absolute value of the normal vector AB is |AB−→|=√( _B − _A ) ² +( _B −
_A ) ² + ( _B − _A ) ² …(9) From the above two absolute values, the distance rc from the rotation axis β to the measurement point C is rc = |AB/−→×AC/−→|/|AB| (10) is required.

As described above, the positioner PS, which is driven separately from the robot and is installed at an arbitrary position, can measure any measurement point on the workpiece rotating on the rotary table 14 and the rotation axis of the workpiece (i.e., the rotation axis of the rotary table). β), that is, the radius of rotation, is determined,
Moreover, this rotation radius is such that the center O of the workpiece is the rotation axis β
Even if it is eccentric from the robot's own coordinate system, it can be determined without any problem as the radius of rotation within the robot's own coordinate system.

The radius of rotation of any point on the rotating workpiece obtained as described above can be used for various operations performed while rotating the workpiece.

Next, an automatic welding method using a rotary table 14 that supports a workpiece and a welding robot that performs work along an arbitrary welding line will be described.

FIG. 12 shows the operating principle when performing circumferential fillet welding on a workpiece 24 similar to the workpiece shown in FIG. 11. In this case, it is assumed that the radius of rotation r _c of the measurement point C has already been determined by implementing the radius of rotation detection method as described above.

Next, rotate the rotary table 14 of the positioner PS to θ〓
The position of point C after rotating around the rotation axis β by an amount of θ and moving the measuring point C by an amount of θ is defined as point C'. This rotation amount θ of the positioner PS is transmitted to the microcomputer 15 on the robot 7 side, and the storage device
Stored in RAM. The operator also drives the robot 7 under PTP control, moves the tip of the welding torch T attached to its wrist by an appropriate distance from point C along the welding line, and teaches the position coordinates of another measurement point D. , stored in the storage device RAM.

The distance r _d from the second measurement point D thus obtained to the rotation axis β can be determined as r _d =|AB×AD|/|AB| (11) in the same way as above.

Next, the angle C′AD=θ _r, that is, the robot 7 is the measurement point.
Vector AC−→′ before moving from C′ to measurement point D,
Find the angle θ _r formed by the vector AD−→ after the movement.

This θ _r can be obtained by sinθ _r = |AC′×AD|/|AC′|×|AD| (12).

This represents the degree of rotation of the robot tip point around the rotation axis β.

Next, add the thus obtained θ _r and the rotation angle θ〓 on the positioner PS side to calculate the angle θ between the direction vector AC―→′ and the direction vector AD―→ after positioner rotation.
Find it as =θ _r +θ〓.

Note that the sign (+, -) of the addition of θ _r and θ〓 depends on the direction of θ _r . As shown in Figure 12, measurement point D is the measurement point
When the measurement point C is located on the opposite side with C' as the center, the sign of θ _r is positive, and when the measurement point D is located on the measurement point C side, the sign of θ _r is negative.

Let rc and r _d obtained by the above procedure be two sides,
Create a triangle whose included angle is θ and find the length of the side opposite θ. Since this calculation is simple, it will be omitted.

If θ is a small angle, the length of this opposite side is an arc
Since it is approximately equal to the distance CD, the length of this opposite side may be regarded as the relative movement distance between the tip of the robot's welding torch T and the workpiece 24. Let the length of this opposite side be L.

Once the radius of rotation of measurement points D and C thus obtained, that is, the distance from the axis of rotation β, and the distance L between them are known, the next step is to turn the welding torch T while rotating the workpiece 24 around the axis of rotation β. It is possible to weld around the arc CD in a fixed state or while moving only in the radial direction, but in actual regeneration work, in the case of a PTP control type robot, welding between measurement points D and C can be performed. is divided into small sections corresponding to the control period of the robot by interpolation calculation, and the robot is sequentially moved using the position coordinates of each dividing point as the target position coordinate. Therefore, in the subsequent control procedure, first, the number of divisions n is calculated by interpolation from the robot's set moving speed v and the robot control period Δt.

Here n=L/V・Δt…(13) The number of divisions n is determined by .

By dividing the angle θ by the number of divisions n thus obtained, the rotation angle Δθ = θ÷n of the rotary table corresponding to one division is obtained, and the rotation table rotates around the rotation axis β by Δθ every Δt seconds. 14 to sequentially position the positioner PS,
In addition, the robot side interpolates the distance between two points between the rotation radii r _d and r _c by the number of divisions n, and moves only linearly in the radial direction to perform continuous welding between DCs. Do the work.

In the above explanation, the distance of the arc DC was replaced by the straight line distance L between the opposite sides of the angle θ, but this is the same as r _c and r _d
Find the average diameter r _n and use this r _n to calculate the travel distance
It is also possible to calculate L' by L'=2πr _n × (θ/360°) (14) and divide it by the number of divisions n determined by equation (13). .

In addition, the control method in the present invention is such that the center O of the workpiece
Since the present invention can be applied even if the center of the rotary table side and the rotation axis β are deviated from each other, the present invention can be applied to a teaching/reproducing operation along an arbitrary work trajectory.

For example, in the case of a workpiece having a shape in which a straight line part and a curved part are continuously combined as shown in FIG. 13, first, the position coordinates of points E and F on the straight part are taught. . At this time the positioner
Since PS does not need to be rotated, θ=0.
Therefore, the interpolation calculation of this part agrees with the linear interpolation of known robots.

Next, point G on the arc portion is taught, but here the rotation axis β rotates. In the figure, the center O of the curved part coincides with the rotation axis β of the rotary table, so there is no need to move the welding torch tip on the robot side by an angle θ _r , but if it is eccentric, the first
This can be handled by moving the robot to move the tip of the welding torch from point C' to point D, as shown in Figure 2.

When the teaching between FG is completed in this way, points H, I, J, and K on the circular arc portion are also taught while rotating the rotation axis β, and the radius of rotation for each point is obtained and the control period of the robot is adjusted. The appropriate division interpolation and the corresponding rotational speed of the rotary table are calculated and stored in preparation for the reproduction operation.

The present invention is particularly effective for workpieces in which a straight line portion and a curved portion are connected. However, if the curved portion is not divided into small sections and taught, a trajectory error will occur.

Furthermore, if the robot 7 has an arc sensing function (arc tracing function), even if the teaching interval is somewhat rough, it can be compensated for by the tracing function.

In the above method, the horizontal axis α is all fixed (stopped)
Although only the case where the horizontal axis α is rotated is shown, it is necessary to newly teach the normal vector and detect the radius of rotation. In this regard, by using the method described below, it is possible to calculate the normal vector on the rotation axis β when the horizontal axis α is rotated by a certain angle.

That is, since position detectors corresponding to the rotation angles are attached to the horizontal axis α and the rotation axis β in the positioner PS, respectively, the angle of the horizontal axis α can be detected and this is set as θ〓. Also, center points A and B on the rotation axis β of the rotary table 14 at a certain θ〓
The robot is guided based on the method described above or taught by inputting data.

Furthermore, the position coordinates of the two points P and Q on the horizontal axis α are also stored by robot guidance or data input.

Using the angle θ〓, vectors AB―→, PQ―→ obtained through the above operations, if the horizontal axis α is rotated to become θ〓′, the vector A′C′―→, that is, the new method How to obtain a line vector will be explained. As shown in Figure 14, the new normal vector A′B′−→ is the vector
It is sufficient to rotate AB−→ around the horizontal axis α, that is, the vector PQ−→, that is, around θ〓′ by (θ〓′−θ〓),
Since this can be easily determined by ordinary vector calculation, the calculation formula will be omitted.

If this method is used, even in the case of a two-axis positioner as described above, once the positioner and robot are installed, the vector can be determined by teaching or data input.
If you teach AB―→ and PQ―→ or input data,
Thereafter, the normal vector AB--> for every θ〓 can be easily found, so the trouble of teaching the normal vector AB--> or inputting data each time can be saved.

In addition, in the case of a robot in which the relative positions of the positioner and robot are fixed (for example, when both are fixed on one base), the above vectors AB - → and PQ are determined when the robot and positioner are assembled. If you teach or input data and store this value in read-only memory ROM etc. built into the microcomputer on the robot side, then you can simply calculate the normal vector AB - → without having to teach or input data at all. By simply inputting the rotation angle θ of the horizontal axis α, the normal vector for determining an arbitrary rotation radius can be automatically determined.

As described above, the present invention is based on the teaching and reproducing type PTP.
In an interlocking control method for a robot and a positioner combined with the robot, the robot is taught a normal vector in the same direction as the rotation axis of the rotary table 14 of the positioner, and two arbitrary center points on the rotation axis. or numerically input data, or data of an arbitrary teaching point on the rotary table in the coordinate system of the robot, and teaching after the position of the point corresponding to the arbitrary teaching point changes when the rotary table is rotated. a step of determining by calculating based on the point data, a step of teaching the robot the position coordinates of an arbitrary measurement point fixed on the rotary table side, and a step of determining the position coordinates of an arbitrary measurement point on the rotation axis and the above measurement point. A radius of rotation comprising the steps of calculating the direction vector between the measurement point and the center point using each position coordinate of the point, and dividing the absolute value of the cross product of the normal vector and the direction vector by the absolute value of the normal vector. a detection step; a step of determining a movement angle of a tip of a tool provided on the robot with respect to the rotation axis of the rotary table; and a step of determining a rotation angle of the rotation axis of the rotary table; The rotation radius detected by the robot, the movement angle of the tool tip with respect to the rotation axis, the rotation angle of the rotation axis, and the set movement speed of the tool tip on the rotary table during interlocking operation, which is input as appropriate data. Since this is an interlocking control method of the robot and positioner that determines the control movement speed of the robot and the rotation speed of the rotary table, it is possible to move the rotary table to any position of the workpiece mounted on the rotary table that is driven separately from the robot. The distance between the robot and the rotation axis, that is, the rotation radius, can be easily read as a value in the robot's coordinate system, and the robot and positioner can be linked together. Moreover, even if the center of the workpiece is offset from the rotation axis of the rotary table, the radius of rotation can be determined without any problem, so the trajectory of an arbitrary shape on the workpiece can be easily taught to the robot. This is an extremely convenient and widely applicable interlock control method. In particular, this method is extremely suitable for application to cases where, for example, a highly versatile multi-axis positioner and a welding robot using the same are linked to perform welding along an arbitrarily shaped welding line.

[Brief explanation of drawings]

Figures 1 a and b are perspective views showing a workpiece having a linear welding trajectory, Figure 2 is a perspective view showing a general welding robot in a welding state on a cylindrical workpiece, and Figure 3 is a perspective view of the cylindrical workpiece. Plan view of 4th
The figure is a perspective view showing the arrangement relationship between a positioner and a welding robot to which the present invention can be applied, and FIG. Flowchart showing,
FIG. 6 is a block diagram showing the mutual signal exchange relationship between the microcomputer, robot, and positioner that can be used in the same control method, FIG. 7 is a perspective view showing the positional relationship between the positioner and the welding robot, and FIG. Figures a and b show the jig attached to the rotary table. Figure a is a side view showing the jig inserted into the rotary table, and figure b is a partial plan view of the jig. Figure c is a conceptual diagram showing the relationship between the absolute value of the cross product of the normal vector and the direction vector and the radius of rotation, and Figure 9 a shows a method of teaching the normal vector of the rotary table by the interlocking relationship with the positioner. Fig. 10 is a flowchart showing the procedure for calculating the normal vector using the interlocking method with the positioner, and Fig. 11 is a diagram showing the welding line. Plan view of cylindrical workpiece when teaching, 12th
The figure is a plan view of a workpiece showing the principle of calculating a welding trajectory when the present invention is used in a continuous welding method with a curved trajectory.
Fig. 13 is a plan view of a workpiece showing a trajectory calculation method for a welding trajectory combining a straight line portion and a curved portion to which the present invention can be applied, and Fig. 14 is a plan view of a workpiece.
FIG. 7 is a perspective view showing a procedure for calculating a vector in the direction of the rotation axis when the horizontal axis of the shaft type positioner is rotated. (Explanation of symbols) β...Rotary axis, 14...Rotary table, C, D, D'...Measurement point, 7...Robot, AB-→
...Normal vector, A, B...Center point, AC-→...Direction vector.

Claims (1)

[Scope of Claims] 1. In a method for interlocking control of a teach/reproduce PTP robot and a positioner combined with the robot, a normal vector in the same direction as the axis of the rotary table of the positioner is set to an arbitrary point on the rotation axis. 2
data that teaches or numerically inputs the center point to the robot, or data of an arbitrary teaching point on the rotary table in the coordinate system of the robot, and corresponds to the arbitrary teaching point when rotating the rotary table. a step of determining by calculating based on a plurality of teaching point data after the position of the point to be measured is changed; a step of teaching the robot the positional coordinates of an arbitrary measurement point fixed on the rotary table side; The process of calculating the direction vector between the measurement point and the center point using an arbitrary center point on the core and each position coordinate of the measurement point, and calculating the absolute value of the cross product of the normal vector and the direction vector by calculating the absolute value of the normal vector. a rotation radius detection step, which includes a step of dividing by a value, and a step of determining a movement angle of a tip of a tool provided on the robot with respect to the rotation axis of the rotary table, and a rotation angle of the rotation axis of the rotary table. , a rotation radius detected in the rotation radius detection step, a movement angle of the tool tip with respect to the rotation axis,
A control movement speed of the robot and a rotation speed of the rotary table are determined from the rotation angle of the rotary shaft and the set movement speed of the tool tip on the rotary table during interlocking operation in which data is appropriately input. Interlocking control method.