JPH0390908A - Industrial robot and its control method - Google Patents

Abstract

PURPOSE:To obtain an industrial robot which can perform the teaching tasks with high efficiency by providing a storage means, a corner front/back point arithmetic means, a command data arithmetic means, and a servo circuit. CONSTITUTION:A CPU-A 12 performs the action control of a robot main body and the processing of a man-machine interface, etc., and also serves as a corner front/back point arithmetic means and a command data arithmetic means. A CPU-B 13 serves as a servo circuit which drives a servo motor doubling as an actuator based on the data received from the CPU-A 12. A CPU-C 14 carries out the communication with a play-back console 3 and a programming unit 4 as well as with a welding machine via a welding machine interface 17. A bubble memory 20 stores the data on the start/end points of the work, the corner points, the aiming angle, the torch speed, etc. In such a constitution, the teaching tasks are faciliated with an industrial robot.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention has a corner point in the middle, and is used to bend at this corner and perform welding work, sealing work, cutting work, etc. from the work start point to the work end point. The present invention relates to a suitable industrial robot and a control method thereof.

[Conventional technology]

When performing welding, cutting, or sealing work using an industrial robot, the tip of the welding/fusing torch or the nozzle that discharges the sealant should be
Of course, it is necessary to move the workpiece along the correct path, but in many cases, it is not possible to obtain good work results just by satisfying this condition.

In addition, the angle of aim of work tools such as torches and nozzles relative to the workpiece must be properly managed.

When the implement is moving in a straight line, it is often desirable to maintain the same aiming angle.

Therefore, conventionally, when teaching a robot to work from the work start point P0 to the work end point P2 by turning from the work start point P0 to the work end point P2, as shown in FIG. At the corner point P□, and at the aiming angles (φ1.θl) and (φ2.θ2), there is a pre-corner point P before and after the corner point, and a point P4 directly after the corner.
All of this information had to be stored in a memory location as program information.

Note that φ is an angle formed with a horizontal plane, and θ is an angle formed with a specific vertical plane.

Then, at the time of playback, based on the program information that has already been taught, the aim angle (φl, θ1) is maintained from the work start point P0 to the pre-corner point P, and the route is interpolated between them, and the pre-corner point P .

From P4 directly after the corner, the route is interpolated between them, and the aim angle is also interpolated from (φ1.θ1) to (φ2°θ2), and P is immediately after the corner.

From to the work end point P2, control was performed to maintain the aiming angle (φ2, θ2) and interpolate the route therebetween.

In addition, as a teaching method for robot path control position or path control i#, Japanese Patent Application Laid-Open No. 1589-1989
No. 82 and those shown in Japanese Unexamined Patent Publication No. 112210/1982 are known.

[Problem to be Solved by the Invention] As explained above, in the conventional industrial robot, in the teaching operation, in addition to the work start point, the work S end point, the corner point located between them, and the aim angle, the corner point is Before and after the corner, you must teach the front point of the corner and the point immediately after the corner. If there are many points that need to be taught, it will take more time to teach, which is inefficient.

The present invention has been made in view of these points, and its purpose is to provide an industrial robot that can efficiently perform teaching work, and a method for controlling the same.

[Means to solve the problem]

That is, in the present invention, one working tool is held, and this working tool is bent at a corner point located between a work start point and a work end point, and is moved from the work start point to the work end point. An industrial robot for working on a workpiece is characterized by having a storage means, a corner front/back point calculation means, a command data calculation means, and a servo circuit.

Among these, the storage means is configured to store positional data of a work start point, a work end point, and a corner point, as well as aiming angle data of the work implement with respect to the work at the work start point and work end point.

The before/after corner point calculation means are the work start point, corner point,
and data of a pre-corner point returned a predetermined distance from the corner point to the work start point side based on the data representing the work end point,
The configuration is such that the calculation is performed to obtain the data of the corner afterward which has proceeded a predetermined distance from the corner point to the work end point side.

The command data calculation means calculates command data to be given to each actuator of the robot in order to interpolate the path while satisfying the respective aiming angle data from the work start point to the pre-corner point and from the corner postpartum to the work end point. The system is configured to calculate command data to be given to each actuator in order to interpolate the posture and path from the pre-corner point to the post-corner point.

The servo circuit is configured to move each actuator based on command data.

A plurality of corner points may exist between the work start point and the work end point.

In such a case, the storage means will of course store data on a plurality of corner points. Further, the corner front/back point calculating means calculates a corner that returns a predetermined distance from the corner point to the work start point or to the corner point at the front stage of the route based on data representing the work start point, each corner point, and the work end point. The data of the previous point and the data of the after-corner which has proceeded a predetermined distance from the corner point to the work end point or to the corner point at the later stage of the route are calculated. Further, the command data calculation means calculates each aiming angle data from the work start point to the first corner front point, from the corner afterturn to the next corner front point, and from the last corner afterfall to the work end point. In order to perform path interpolation while satisfying the following, the command data to be given to each actuator of the robot is determined. It is configured to perform posture interpolation.

Route interpolation includes work start point, pre-corner point, post-corner point,
Interpolation can be performed between work end points in a straight line, or interpolation can be performed while performing a weaving operation on a line connecting the work end points with a straight line.

Furthermore, the work implement may pass over the corner point, or may pass near the corner point without passing over it.

A common microcomputer can be used in a time-sharing manner as the corner front/back point calculating means and the command data calculating means.

Further, the control method is characterized in that it includes a storage step, a corner front/back point calculation step, a command data calculation step, and a servo control step.

Among these, in the storage step, position data of the work start point, work end point, and corner point, as well as aiming angle data of the work tool with respect to the work at the work start point and work end point are stored.

In the before/after corner point calculation process, based on the data representing the work start point, corner point, and work end point, the data of the front corner point returned a predetermined distance from the corner point to the work start point side, and the work end point from the corner point are calculated. The data of the corner after a predetermined distance to the point side is obtained by calculation.

In the command data calculation process, command data to be given to each actuator of the robot in order to interpolate the path while satisfying the respective aiming angle data from the work start point to the pre-corner point and from the corner post-corner point to the work end point is calculated. Find the command data that should be given to each actuator to interpolate the posture and path from the pre-corner point to the post-corner point.

In the servo control process, each actuator is moved based on command data.

In the storage step, data on the work start point, corner point, and work end point may be generated by the teaching work, or it is also possible to generate each data by activating the sensor prior to the work.

[Effect]

By doing the above, the pre-corner point and the post-corner point are automatically generated, making the teaching work much easier than in the past.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 to 4.

FIG. 2 shows the overall configuration of this embodiment.

1 is the robot body, which is driven by a 6m actuator. 2 is a robot control section. 3 is a playback console, which is used to start, stop, etc. during automatic operation. 4 is a programming unit which mainly performs teaching work for the robot. 5 is a welding machine, which is composed of a welding power supply section and an interface section.

6 is a welding wire, which is driven by a wire supply position 7. 8 is a torch as a working tool.

V, Figure 1 is a robot [i'l! It is a book diagram of position II.

The CPU-Al2 in the robot control unit 2 is responsible for processing the movement sub-legs of the robot main body, the man-machine interface, etc. It also functions as a direct calculation means before and after a corner, and as a command data calculation means. The CPU-B 13 works as a servo circuit to drive the servo motor as an actuator based on the data sent from the CPU-Al2.
The U-C 14 communicates with the playbank console 3 and the programming unit 1-4, and also communicates with the welding machine via the welding machine interface 17. 18 is a RAM-A, which stores a program that describes the processing procedure of the CPU-A.

Reference numeral 21 denotes RAM-B, in which a program describing the processing procedure of CPU-B is stored. A RAM-C 22 stores a program that describes the processing procedure of the CPU-C. 19 is a ROM, which stores a processing program for loading the program stored in the bubble memory 20 into the RAM-A at the time of initialization. Further, the bubble memory 20 is a non-volatile external storage location, and stores data such as work start point, corner point, work end point, aiming angle, and further data such as torch speed. In other words, the bubble memory 20 functions as a storage means. The welding machine interface 17 transfers commands such as wire feed amount, voltage, arc ON, etc. to the welding machine.

Next, an embodiment of this control method will be described using the flowchart of FIG. Here, the position and orientation of a point will be expressed as a pose as follows.

In equation (1), the 1st, 2nd, and 3rd vertical columns represent the attitude including the aiming angle, and the 4th vertical column represents the position.

Next, a method of calculating automatically generated points for pre-corner, post-corner PJ and P4 in this embodiment will be explained with reference to FIGS. 3, 4 and 5. In addition, Fig. 4 shows the points to be taught, where Po is the work starting point, Pl is the corner point, and P2 is the starting point.
is the work end point.

These data, as well as attitude data for specifying the aiming angle and torch speed data, are stored in the storage means 20 as shown at 39 in FIG.

After reading each of these data according to FIG. 3, 40, in 41, the direction vectors L1 and L2 of the welding line are calculated.

L engineering=(P□-P.)/I P□-P. 1(2) L2=(P, -1'□)/I P2-Pll Here, 1 1 represents the (norm of the vector. Next, point P0
At step 42, the I11 determination is made as to whether or not is a corner point. This judgment is made based on the inner product of L and L2 obtained using equation (1).

Ll・L2≦K (3) Here, · represents the inner product of the vectors in Table 4. K in equation (3) is determined by the angle formed by the edge and L2 when determining a corner. For example, if the angle formed by the weld line is larger than 30 degrees, it is considered to be part of a corner, then K=cos30'=0.7 (36(4)) may be used.

If equation (3) is true, the process proceeds to step 43.

43, the Bose of the pre-corner point P in FIG. 5 is calculated.

From a distance away from the corner point P□ (point P
, ) When trying to change the torch pose, the pose of P is as follows.

Next, in step 44, the pose of the corner back P4 is calculated.

Next, in step 45, the attitude of the corner point P1 is calculated.

Since the change in posture from P□ to P-work must be the same as the change in posture from Pl to P4, it becomes.

As described above, the points to be interpolated (Po, Pl, P2°P3.
and P4), now we will use them to perform interpolation.

In the interpolation period, the a-tangential velocity vw is set by the user. Now, assuming that the interpolation period of the robot is ΔT, a method for determining the pose of the first interpolation will be explained.

Now, set the poses of the interpolation start point and end point (8) Then, the interpolated distance is as follows.

L= l F, -P, + (9
) Also, the amount of change in position and orientation in the interpolation interval is △L =
P, -P.

Δn=n, -n.

△o=o, -o.

△a = a * - & 5 (10) It is expressed as

Also, the amount of change in position during the interpolation cycle is △P=v, X△
T (11).

From equations (8), (9), (10), and (11), the pose of the first interpolation is as follows.

By the way, according to the experiment, it was found that the welding speed near the corner must be slower than the set welding speed, so the welding speed near the corner (from point P in Figure 5 to point P1 and point P to P4) is calculated as follows: 46.

vc=v,,Xm (13)(0〈m
≦1) Here, m is a value determined by experiment.

If formula (13) is used, the amount of change in position during the interpolation cycle near the corner will be ΔP, = v, XΔT (14), so if this is used instead of ΔP in formula (12), good.

Using the interpolation method described above, in the case of corner welding, point P is determined. → P, -P engineering → P4 → P2, otherwise P. -+P, →P2 are interpolated in the order of 4.
It is 7.48.

Note that the data obtained through interpolation is expressed in the robot coordinate system, so in order to actually operate the robot, these data must be converted into robot! It must be converted to the leap angle of .

Further, the upper part (above the broken line) of the flowchart in FIG. 3 described in this embodiment can be performed both during program teaching and during preback execution. Also,
By using the upper part of the flowchart in FIG. 3 when controlling the robot from the outside using an offline program or the like, the same effects as in this embodiment can be obtained.

Note that the calculations of equations (1) to (14) are performed by CPU-A. Further, the servo means moves each actuator using a signal representing the difference between the interpolated data obtained in step 48 and the current position data (encoder data) possessed by each actuator M□ to MG.

In this embodiment, the torch attitude is expressed using hectors, but the same effect as in this embodiment can be obtained even if this is expressed using another expression such as the Euler angle.

In addition, in this embodiment, in FIG. 5, assuming that the posture of point P2 has been obtained by teaching, this posture is changed to P4.
As reflected in this example, even if the welding dominance of P4 is calculated so that the relationship between the welding posture and the welding direction at Po is the same as the relationship between the welding posture and welding direction at P4, the result will be the same as in this example. You can get the following effect.

According to this embodiment, there are the following effects.

(1) Since welding postures near corners are automatically generated, teaching in corner welding can be simplified and welding quality can be improved.

(2) Optimizes the welding speed near corners, improving welding quality.

(3) Since it is automatically determined whether the object is a corner or not, teaching is simplified.

〔Effect of the invention〕

According to the present invention, the data immediately before and after the corner is used as the work starting point.
Since it is automatically generated from the corner point and work end point data, it has the effect of making the teaching work easier.

[Brief Description of the Drawings] Fig. 1 is a block diagram of main parts showing an embodiment of the present invention;
Fig. 2 is an overall system diagram of the position, Fig. 3 is a flowchart 1 showing an embodiment of the control method of the present invention, Fig. 4 is a conceptual diagram showing teaching points according to the method, and Fig. 5 is a diagram according to the conventional method. FIG. 3 is a conceptual diagram of a teaching point working state according to the method of the present invention. P is the work start point, P□ is the corner point, P2 is the work end point, P is the pre-corner point, P4 is the post-corner point, 12 is the central processing position as the pre-corner/contact calculation means and the command data calculation means. , 13 is a central processing position as a servo means, and 20 is a storage means. Easy map 2nd closed area

Claims (1)

[Claims] 1. Holds a work tool, bends the work tool at a corner point located between a work start point and a work end point, and moves the work tool from the work start point to the work end point. In an industrial robot that performs work, each position value data of the work start point, the work end point, and the corner point, and the aiming angle data of the work tool with respect to the workpiece at the work start point and work end point are stored. a storage means for storing the data representing the work start point, the corner point, and the work end point based on the data representing the work start point, the corner point, and the work end point; a corner front/back point calculation means for calculating data of a corner rear point that has proceeded a predetermined distance toward the end point; Up to this point, command data to be given to each actuator of the robot is determined in order to interpolate the path while satisfying the aiming angle data, and from the front point to the back point of the corner, the command data is calculated to interpolate the posture and path. An industrial robot comprising command data calculation means for determining command data to be given to each of the actuators, and servo means for moving each of the actuators based on the command data. 2. The industrial robot according to claim 1 is characterized in that a common microcomputer is configured to be used for the corner front/back point calculating means and the command data calculating means in a time-sharing manner. industrial robot. 3. Holds a work tool, turns the work tool sequentially at a plurality of corner points located between a work start point and a work end point, and performs work on the workpiece from the work start point to the work end point. In the work robot that performs the work, position value data of the work start point, work end point, and the plurality of corner points, as well as the aim of the work tool toward the workpiece between the work start point, work end point, and each corner point. a storage means for storing corner data, and based on the data representing the work start point, each corner point, and the work end point, return from the corner point a predetermined distance to the work start point or the corner point located at the previous stage of the route. Corner front/back point calculation means for calculating data of a corner front point and a corner rear point after proceeding a predetermined distance from the corner point to the work end point or a corner point at a later stage of the route. and, from the work start point to the first corner front point, from the corner back point to the next corner front point, and from the last corner rear point to the work end point, each of the above aim angle data is satisfied. In order to perform path interpolation, the command data to be given to each actuator of the robot is determined. An industrial robot comprising: command data calculation means for determining command data to be given to each of the actuators in order to perform posture interpolation; and servo means for moving the actuators based on the command data. 4.Industrial use, which holds a work tool, bends the work tool at a corner point located between a work start point and a work end point, and performs work on a workpiece from the work start point to the work end point. In a robot control method, a memory for storing positional value data of the work start point, work end point, and corner point, as well as an aiming angle of the work tool with respect to the workpiece at the work start point and the work end point, as data. Based on the data representing the work start point, corner point, and work end point, the data of the pre-corner point returned a predetermined distance from the corner point to the work start point side, and the data representing the work start point from the corner point. a corner front/back point calculation step that calculates the data of a corner rear point that has proceeded a predetermined distance toward the end point side; calculates the command data to be given to each actuator of the robot in order to interpolate the path while satisfying each of the aiming angle data, and from the front point to the back point of the corner, the command data to be given to each actuator of the robot is A method for controlling an industrial robot, comprising: a command data calculation step for determining command data to be given to each actuator; and a servo control step for moving each actuator based on the command data. 5. Holds a work tool, and performs work on the workpiece from the work start point to the work end point by sequentially bending the work tool at a plurality of corner points located between the work start point and the work end point. In the method for controlling a working robot, the position value data of the work start point, the work end point, and the plurality of corner points, and the position value data of the work tool between the work start point, the work end point, and each corner point are provided. a storage step of storing aiming angle data for the work; and a predetermined movement from the corner point to the work start point or to the corner point at the front stage of the route based on the data representing the work start point, each corner point, and the work end point. Before/after corner points obtained by calculating the data of the pre-corner point that has returned a distance and the data of the post-corner point that has proceeded a predetermined distance from the corner point to the work end point or the corner point at the later stage of the route. During the calculation process, from the work start point to the first corner front point, from each corner back point to the next corner front point, and from the last corner back point to the work end point, each of the aim angle data is used. In order to interpolate the path while satisfying the following, find command data to be given to each actuator of the robot,
Command data for determining command data to be given to each actuator in order to perform path interpolation from the front point of each corner to the end point of the next corner and posture interpolation between the two aim angles commanded across the corner point. A method for controlling an industrial robot, comprising: a calculation step; and a servo control step for moving the actuator based on the command data.