JPH01206405A - Robot controller - Google Patents

Abstract

PURPOSE:To attain a spiral weaving action with less teaching points by specifying a main path by means of the teaching points of a start point and an end point and specifying the size of a circle which executes the spiral action and a plane on which the circle is drawn by means of three teaching points. CONSTITUTION:In a work piece 21, the main path 41 is teached by the start point P0 and the end point P1. On the other hand, a basic circle 42 is teached by the start point P0 and the other points P2 and P3 for giving the size and direction of the circle which is drawn spirally as the weaving action. Consequently, the teaching points for executing the spiral weaving action come to four. The teaching points are stored in a teaching point storage means 1, and a command position on the main path is calculated in a main path position calculating means, whereby the command position on a circumference is calculated in a circumferential position calculation means 3. An objective position calculation means 4 adds the command position on the main path and that on the circumference and a respective axes driving means 5 executes drive according to the target position.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application j] The present invention relates to an industrial robot, and particularly to a robot control device suitable for performing polishing work.

``Prior Art'' When arc welding is performed on the butt portions of automobile frames, it is necessary to polish the weld metal using a rotating grindstone in order to remove the bulges caused by the weld metal and make the surface smooth. Conventionally, this polishing work was performed by a robot controlled by the same control device as the welding robot. A conventional robot control device calculates and controls a movement path by performing linear or circular interpolation between taught points.

However, when polishing arc welded parts,
If the grinding wheel was simply moved linearly along the welded part, the grinding area would overheat, causing burns on the automobile frame, making it difficult to ensure quality. Although the weaving operation used in welding work is slightly improved, the weaving function of conventional equipment is simple harmonic (a), triangular (b), or figure 15, as shown in Figure 9. This is pattern (c), and these weaving operations still have the problem that scorching is likely to occur, and that a good finish cannot be obtained because streaks remain on the polished surface.

By the way, when polishing is done manually, experience shows that this kind of weaving motion, which is performed by moving a rotary whetstone in a spiral while drawing a circle, is suitable for polishing and does not cause burns. known to. but,
If a conventional robot device were to move the robot along a welded part in a spiral manner, it could only perform circular interpolation, so a large number of teaching points had to be given, which was very troublesome.

"Problems to be Solved by the Invention" The present invention was made to solve the above problems, and it is possible to perform a weaving operation that moves in a spiral shape while drawing a circle along the welded part by only providing a few teaching points. The purpose of the present invention is to provide a robot control device that can perform the following operations.

``Means for Solving the Problems J'' In order to achieve the above object, in the present invention, as shown in FIG. Teaching point storage means 1
and a main route position calculating means 2 that interpolates the main route from the taught starting point to the ending point and calculates the commanded position of the main route L.
and the circumferential position vr at which the command position on the circumference is calculated by interpolating the second position on the circumference of the base circle specified by the Moeki teaching point.
l'f1 output means 3 and the command on the main path (I7'ft
and a command position on a circumference to calculate a target position; and a drive means 5 that drives a drive device for each axis according to the target position. is provided.

[Operation] According to the robot control device of the present invention refined as described above, the main path corresponding to the welding part is specified by two teaching points, the starting point and the ending point. The size of the arc for performing the spiral motion and the plane on which the circle is drawn are specified by three teaching points that specify the base circle. Since one of the three teaching points for specifying the base circle can be made common to the starting point or end point of the main route, the main route and the base circle are ultimately specified by the four teaching points.

” - When the few teaching points are taught and started given the feed rate and circular arc frequency, the target position at the momentary current time is the command position on the main path (circle)! 1
It is calculated by adding the above commanded positions, and the drive devices of each axis are driven to realize the target position.

Embodiment 1 An embodiment of the present invention will be described with reference to the drawings. Second
The figure is a perspective view showing the robot 10.

This robot t is an articulated robot with 6 degrees of freedom, and performs polishing work using a 1I1 grinding wheel 19 attached to the tip of the arm.The workpiece is an automobile frame 21, with a pillar 22 and a roof 23. Polishing work is performed to smoothen the welded part 24 where the welded part 24 is arc-welded.

Explain the structure of the robot. A trapezoidal swing base 12 is supported on a fixed base 11 so as to be rotatable in a horizontal plane about a first axis A1 having a lead angle, and is driven to swing by a first shaft drive motor M1. A first arm 13 is swingably supported on the swing base 12 about a horizontal second axis &lA2, and is swingably driven by a 211Ih drive motor M2. A cylindrical second arm 14 is supported on the first arm 13 so as to be swingable about a horizontal third axis 83, and is swingably driven by a third axis drive motor M3 (not shown). A twist wrist 15 is rotatably supported at the tip of the second arm 14 about a fourth axis A4 at the center of the second arm 14, and is driven to rotate by a motor M4. A pend wrist 16 is supported on the twist wrist 15 so as to be able to rotate around a fifth axis A5, and is driven to rotate by a fifth axis drive motor M5 (not shown).The fifth axis A5 is inclined with respect to the fourth axis A4. The pend list is located in the direction of 16". Second,
A swivel wrist 17 is supported so as to be able to rotate about a sixth axis A6, and is driven to rotate by a sixth axis drive motor M6 (not shown). The sixth axis 86 is provided in a direction inclined with respect to the fifth axis A5. The swivel list 17
A tool head 18 with one rotating grindstone is mounted above. Each of the shaft drive motors M1 to M6 is a pulse motor, and each shaft drive motor M1 to M6 is provided with a pulse encoder [1 to E6] for detecting the position. Each of the motors M1 to M6 and pulse encoders E] to E6 are connected to and controlled by a robot control device 30.

FIG. 3 is a block diagram showing the robot control device 30. As shown in FIG. The robot control device 30 has a CPU 31 and a central processing unit 1jl.
j device), memory 32. CRT console integrated with display 33. Operating box (OB), which is a portable operation panel 34. It includes servo drive units D1 to D6 and a tool drive unit 35 for each axis. C.P.
In U31, the teaching points taught by the JOG operation from the CRT console 33 and operating box 34 are stored in the memory 32, and the target positions of each axis J1 to J6 are calculated by performing interpolation calculations etc. based on this information. The target position θ3. θ2...
・Output θ. Further, the CPU 31 controls the tool drive unit 35. Servo drive unit D1-D for each axis
Reference numeral 6 includes a CPU for servo control, and a target position θ commanded by detecting position signals from pulse encoders E1 to E6.

- θ6 is controlled by controlling each shaft drive motor M1 to M6.

Based on the above hardware configuration, the control concept of the present invention will be explained with reference to FIG. 4. Along the seam corresponding to the welded portion 24 of the workpiece 21, the main path 41 is taught by two teaching points, a starting point P0 and an ending point Pl. The main path 41 is specified as a straight line connecting the starting point P0 and the ending point P. In order to give the size and direction of the circle drawn in a spiral shape as a weaving operation, the base circle 42 is set at the starting point P0 and two other points P2. As taught by P. These three teaching points po, P2. The base circle 42 is specified by the circle passing through Pz, and the plane 43 including the base circle 42, that is, the plane 43 of the weaving operation in which the rotary grindstone 19 moves in a spiral shape is specified. The teaching point for making a spiral weaving motion is Po.

P+, P2.　P　*4 points.

In the CPU 31, the starting point P0 is set by the weaving start command.
Linear interpolation is performed between P1 and the end point P1, and the command value ff''ro(t,) of the main path 41-to at every moment is calculated in real time.At this time, the command value of the feed rate given in advance is In addition, the position on the circumference of the base circle 42 is calculated by circular interpolation, and the commanded position R(t) of the circumference north 44 at the time of the birth is calculated in real time. Then, the two calculated command positions 'to(t) and R(t) are added to calculate the instantaneous position JT(t).

'r(t)=TO(t)+R(t)
...(1) Next, CPU 31 C: Convert the aK position 'rl''r(t) into the target angular position of each drive axis, J1 to J6, that is, joint coordinates, and The target position θ8.
θ, ... θ6 are output.

In this way, as shown in FIG. 5, the starting point is reached.

to the end point I] 1 in a spiral manner, and there are few teaching points P0 to P, thereby creating a spiral motion locus 45.
It is possible to perform a weaving motion to draw.

FIG. 6 is a flowchart 1- showing the actual processing. First, in step 101, the fat position 1' on the 4-path at the current time is determined. is calculated by linear interpolation. To
is given by a matrix such as equation 1.

Here, [N], [0], and [A] are matrices that give the attitude of the tool head 18, and [P] is a matrix that gives the spatial position.

Next, in step 102, an interpolation point on the circumference of the base circle 42 on the plane 43 is calculated by circular interpolation, and then in step 103, the interpolation point is converted to world coordinates (coordinates in space), and A command position R on the circumference 44 is calculated. R is given by a matrix as shown below.

In step 104, L (target position 1'' is calculated as T = ``I゛.+R''. The target position '1' is given by the following matrix.

Next, in step 105, this target position] is set at joint coordinates J(θ1, θ2,
... θ6), and further, in step 106, the target values E (El.

E2...E6) and applied to the servo drive units D1 to D6 of each axis.

Then, in step 107, time t is incremented by Δ, which is the next interpolation timing, and steps 108 to 10
Go back to step 1 and repeat the above process.

When the end point P1 is reached, the process proceeds from step 108 to step 109, and the process 100 is terminated.

In the embodiment described above, two straight lines were interpolated between the starting point P0 and the ending point I)l, and the main path 41 was made into a straight line, but as shown in FIG. 7, the starting point ■). and the end point G), perform circular interpolation between
It is also easily possible to perform a spiral weaving operation 52 along the arcuate main path 51.

In addition, as shown in Fig. 8, the weaving operation is performed using the basic circle 4.
It is also possible to perform the weaving operation 53 in an arc shape instead of a spiral shape by reciprocating a part of the arc of the base circle 42 instead of over the entire circumference of the base circle 42.

Further, in the above embodiment, the polishing work after welding was explained as an example, but the welding work can also be suitably applied to polishing work, painting work, and sealing work.

"Effects of the Invention" As explained above, since the present invention is configured as described above, a spiral weaving motion that draws a circle or a weaving motion that draws an arc can be performed with a small number of teaching points, and the teaching This has the excellent effect of significantly reducing time. In particular, when a spiral weaving motion is applied to a robot that performs polishing work on welded parts, a good finished surface is obtained without burns or streaks on the polished surface, improving quality. This effect is achieved.

[Brief explanation of the drawing]

1 to 8 show embodiments of the present invention, No. 11N is a diagram clearly showing the configuration of the invention, FIG. 2 is a perspective view showing the robot, and FIG. 3 is a block diagram of the 17-bot control device. FIG. 4 is a perspective view explaining the control v4 concept, FIG. 5 is a plan view showing the weaving operation, FIG. 6 is a flowchart showing the process, and FIGS. 7 and 8 are plan views showing different weaving operations. , FIG. 9 is a perspective view showing the weaving operation of a conventional device. 10.,,Robot, 1.8. ,, tool head, 1
9., Rotary grindstone, 21. , Workpiece (automobile frame), 24 , Welded part, 30 , Robot control device, 31 , CPU, 32
．． ,,Memory 41, ,Main path, 42. ,, base circle. Figure 5, t, 5 42・' Figure 7 Figure 8 42'

Claims (1)

[Scope of Claims] Teaching point storage means for storing points specifying the start point, end point, and base circle of weaving action as teaching points; main path position calculation means for calculating a command position on the circumference of the base circle specified by the teaching point; A target position calculating means for calculating a target position by adding a command position on a path and a command position on a circumference, and a drive means for driving a drive device of each axis according to the target position. Robot control device.