JPS62120995A - Method of preventing interference in robot - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a method for preventing interference in a robot, which prevents a tool attached to the wrist of the robot from interfering with the robot body, etc. due to rotation of the wrist. be.

<Prior art> In general, in a six-axis control robot, the wrist is supported at the tip of the robot body so that it can rotate around three axes that are orthogonal to each other, and each of these axes has a defined range of motion. The wrist can be moved freely within this range.

<Problems to be solved by the invention> By the way, there are six cases in which this type of robot is applied to laser processing.
In an axis-controlled laser processing machine, a relatively long tool (torch) is attached to the tip of the wrist. A situation arises that interferes with the

However, in the current situation, tool interference is only avoided based on the operator's judgment, and for example, during teaching, it is necessary to use considerable care to avoid tool interference.

Means for Solving the Problems> The present invention has been made to solve the above-mentioned problems of the conventional art. The angle range that interferes with the robot body or the wrist is set for each of the two axes, and when the command angle of the two axes falls within the set interference range when commanding the wrist, an error message is output. It is designed to restrict the movement of the wrist.

<Example> Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows a laser processing machine using a six-axis control robot, and this laser processing machine is based on a Cartesian coordinate robot 10. As shown in FIG. The robot 10 has two columns 1) that are parallel to each other, a table 12 that can slide on the columns 1) while being guided in the X-axis direction, and a table 12 that can slide on the table 12 while being guided in the Y-axis direction. Carriage 13 and
The head 14 is guided and slidable on the carriage 13 in the Z-axis direction. Furthermore, a fourth axis wrist part 15 is supported at the tip of the head 14 so as to be rotatable around an axis parallel to the Z axis, and this fourth axis wrist part 15 is rotatable around an axis perpendicular to this. A fifth-axis wrist portion 16 is supported at the end of the fifth-axis wrist portion 16, and a sixth-axis wrist portion 17 is supported at the tip of the fifth-axis wrist portion 16 so as to be pivotable about an axis perpendicular to the fifth-axis wrist portion 16. A tool (torch) 18 is attached to the sixth axis wrist portion 17, and a laser beam oscillated by a laser oscillator of the circuit is irradiated from the tool 18 toward the workpiece.

In addition, in the following explanation, the fourth. Fifth. The sixth axis wrist portions 15, 16, and 17 are simply referred to as the fourth axis, fifth axis, and sixth axis.

Fig. 2 shows the robot control circuit, and 2° is a central processing unit consisting of a microcomputer, etc. This central processing unit 20 includes a memory 25, and servo motors M1 to M1 for each axis attached to the robot. Servo motor drive circuits 22a to 22f for driving the M6, and an operation panel 26 for instructing teaching points are attached. Each of the servo motor drive circuits 22a to 22f calculates the deviation between the output data output from the central processing unit 2o and the output of the encoder El-E6 connected to the servo motors M1 to M6, and calculates the magnitude of this deviation. Each servo motor M1 to M6 at a speed according to the
It is designed to drive.

The memory 25 stores data representing the positioning point of the tool 18, and also stores a robot operation program input by operating the operation panel 26. Further, the memory 25 is provided with an area for storing data representing the interference area, and data of the interference area calculated as described later is stored in this area.

Next, in the 6-axis control laser processing machine having the above configuration, an angular region in which the tool 18 interferes with the robot main body (head 14) or the fourth axis is set by a combination of rotations of the fifth and sixth axes. The processing will be explained with reference to FIGS. 3 to 7.

First, the process of setting the operating limit of the fifth axis will be explained with reference to FIG. 3. In the figure, 05 is the rotation center of the fifth axis, and this is taken as the coordinate origin Os (x=O, y=0). Further, P l r P 2 indicates a representative point of the robot body 14, and P5 indicates a representative point of the tip of the tool 18. Here, if the X coordinate value of the straight line PIP2 connecting representative points Pl+P2 of the robot body 14 is -m, the tool 18 interferes with the robot body 14 due to the clockwise rotation of the fifth axis because the tip of the tool This is a case where the X coordinate value of the representative point P5 becomes larger than -m. Therefore, the X coordinate value x of the tool representative point P5
5 by finding the angle α such that x5=-m.
Allows you to set the operating limits of the axis.

The following describes the angle α and the process of calculating the interference occurrence area of the fifth axis from this angle α. Here, if the intersection of the rotation axis of the sixth axis and the center line of the tool 18 is 06, then the points Os, o
Distance between two points 'l of 6 + distance 12 from point 06 to the tip of the sixth axis, axial length of the tool 18, that is, distance Mt from the tip of the sixth axis to the tip of the tool, radial dimension t2 of the tool 18
is registered in the memory 25 as a known dimension. The tip representative point P5 of the tool 18 described above is defined as 06', which is the intersection of the tip surface of the tool 18 and a straight line that is parallel to the center of the tool and spans the radius in the radial direction.

Therefore, the angle .alpha. at which the X coordinate value of the point P5 becomes -m can be calculated using the following formula from two right triangles having a common side shown in FIG.

α=90°−(A1+A2) 1=(12+t+)/(6+t2) From the angle α calculated in this way, the angular range of the fifth axis in which the tool 18 does not interfere with the robot body 14 is the fifth axis. From the original position shown by the two-dot chain line in the figure, there is an angle a in the child direction (clockwise) and an angle in one direction (counterclockwise), and these angles a,
b are stored in a predetermined data area of the memory 25 as the upper and lower limits of the interference occurrence area of the fifth axis.

Next, the process of setting the operating limit of the sixth axis will be explained with reference to FIG. In the figure, o6 indicates the rotation center of the sixth axis,
This is defined as the coordinate origin Os (x=o, y=0). Also P3. P4 is the representative point of the robot body 14,
P6 indicates a representative point of the tool 18. Here, if the X coordinate value of the straight line P3P4 connecting the representative points P3 and P4 of the robot body 14 is m, the tool 18 interferes with the robot body 14 due to the counterclockwise rotational movement of the sixth axis. This is a case where the X coordinate value of the 18 representative point P6 becomes smaller than m. Therefore, by finding the angle β at which the X coordinate value X6 of P6 satisfies x6=m, it becomes possible to set the operating limit of the sixth axis.

The angle β and the process of calculating the interference occurrence area of the sixth axis from this angle β will be described below.

In this case, based on the same idea as in the case of the fifth axis described above, the angle β at which the X coordinate value of the point pg6 is m can be calculated using the following formula from the two right triangles having one side in common as shown in FIG. It can be calculated as follows.

β=90'-(A3+A4) tanA3= t2/l-2sinA4=
m/57 pieces=51 Therefore, the angular range of the sixth axis in which the tool 18 does not interfere with the robot body 14 is an angle C2 in one direction (clockwise/J) from the original position shown by the two-dot chain line in FIG. counterclockwise)
The angle d becomes the angle d, and these angles c and d are stored in a predetermined data area of the memory 25 as the upper and lower limits of the interference occurrence area of the sixth axis.

In addition, FIG. 7 shows a flowchart for calculating the upper limit value, lower limit value a, b, c, and d of the interference occurrence area of the fifth and sixth axes described above.

Next, the operation of the six-axis control laser processing machine will be explained based on the flowchart of FIG.

First, in step 50, a motion command θ4. θ5. θ6 is given, then step 5
1, upper and lower limit values a, b, c, and d of the interference occurrence area of the fifth and sixth axes are read out from the memory 25. In step 52, it is determined whether the command angle θ5 of the fifth axis is larger than the lower limit value a and smaller than the lower limit value (a
≦θ5≦b) is determined, and in the case of No, step 53
The process moves to step 54, where the operation command is executed, and if YES, the process moves to step 54. In step 54, the command angle θ6 of the sixth axis is larger than the upper limit value C and lower limit value d.
It is determined whether it is smaller than (C≦θ6≦d), and No.
If YES, the process moves to step 53, where the operation command is executed, and if YES, the process moves to step 55, at which a message indicating the occurrence of interference is output.

In this way, only when the command angles of the 5th and 6th axes are both in the interference generation area, an error message indicating that interference has occurred is output and the robot movement command is stopped, and the 5th and 6th axes If any one of the commanded angles is outside the interference occurrence area, the operation command is executed assuming that there is no risk of interference.

In the above embodiment, an example was described in which a 6-axis control robot was applied to a laser processing machine, but the present invention is applicable to applications such as welding or painting where a tool attached to the wrist may interfere with the robot body. The invention can also be applied to working robots, and the number of control axes is not particularly limited to six, but can be applied to robots that have a wrist section that can control at least two axes.

<Effects of the Invention> As described above, in the present invention, interference areas are set in advance for each of the two axes of the wrist of the robot, and when a motion is commanded, the robot is attached to the wrist by a combination of the motion command angles of the two axes. The system determines whether the tool will interfere with the robot body, etc., and outputs an error message based on the determination result to prevent the tool from interfering with the robot body or wrist, improving robot safety. Moreover, since there is no need to be nervous during teaching, the burden on the operator can be reduced and the teaching time can be shortened.

[Brief explanation of drawings]

The drawings show embodiments of the present invention, and FIG. 1 is a perspective view showing an example in which a 6-axis control robot is applied to a laser processing machine, FIG. 2 is a diagram showing a robot control circuit, and FIGS. The figure shows the operation for setting the interference angle area of the wrist of the fifth axis and the sixth axis.
FIG. 7 is a flowchart for setting the interference angle area, and FIG. 8 is a flowchart for executing the operation command. 14...Robot body part, 15.16.17...Wrist part, 18...Tool.

Claims (2)

[Claims] (1) A method in which a robot body is provided with a wrist part that can be controlled in at least two axes, and a tool attached to the wrist part is prevented from interfering with the robot body or the wrist part, and the tool is attached to the robot body or the wrist part. The angle range that interferes with the wrist part is set for each of the two axes, and if the command angles of the two axes both fall within the set interference range when commanding the wrist part, an error message is output and the wrist part A method for preventing interference in robots that limits movement. (2) The interference area of the two axes is determined by calculating angles of the two axes at which the representative point of the tool corresponds to the coordinate values of the representative point of the robot body or the wrist. A method for preventing interference in a robot according to scope 1.