JPH04232512A - Attitude teaching method for robot - Google Patents

Abstract

PURPOSE:To present an attitude teaching method for a multijoint welding robot by very easily and correctly teaching an objective torch angle and the attitude of the welding robot adapted to this angle. CONSTITUTION:Three parameters, namely, an angle alpha of inclination of a welding torch 7 to a reference face O including a weld line L (work line), an angle betaof pulling/pushing of the welding torch 7 to the weld line L, and an angle gammaof rotation of a wrist member 6 gripping the welding torch 7 to the axis of the welding torch 7 are inputted, and the attitude of the welding torch 7 is determined based on them, and the angle of each joint of this robot is determined based on data related to the attitude of the welding torch 7 and the front end coordinate values (position vector W) of the welding torch 7.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for teaching the posture of a multi-jointed robot, which is equipped with, for example, a welding torch at the tip of an arm so as to be rotatable about the axis of the arm.

0002

BACKGROUND OF THE INVENTION This type of posture teaching method is conventionally known, for example, as disclosed in Japanese Patent Laid-Open No. 63-256281. In the technology disclosed in the above publication, in a 6-axis articulated welding robot, the torch angle α, advance angle β, and the coordinates P(P1, P1,
P2, P3), the angle at each joint of the robot is determined. Specifically, the torch direction vector T (T1
, T2, T3) are determined, and the joint angles .theta.1 to .theta.6 of the robot are determined by inverse transformation using this direction vector T and the coordinates P of the tip of the torch.

[0003] In addition to the technology disclosed in the above-mentioned publication, there is a generally known technology in offline teaching and online teaching in which the operator inputs and corrects each joint angle while looking at a CRT screen or the actual machine, and adjusts the joint angle to meet the purpose. There are known methods such as a method of approaching the torch angle to a certain value, and a method of inputting roll, pitch, yaw angles, Euler angles, etc. to teach the torch attitude.

0004

[Problem to be Solved by the Invention] However, in the technique disclosed in the above publication, five (P1, P2, P3, α,
Since the angles of each of the six joints in a six-axis welding robot are calculated based on the parameter β), one parameter is missing, and there are an infinite number of possible postures for the welding robot. , causing problems such as loss of control. In addition, in the method of teaching by inputting each joint angle using offline teaching or online teaching, the operator must approach the desired torch angle through trial and error, which is slow and slow to operate, and requires accurate positioning settings. Can not do it.

Furthermore, in the method of teaching by inputting roll, pitch, yaw angles, Euler angles, etc., it is difficult for the operator to understand what angle the welding torch should take with respect to the welding line, and the teaching is difficult. The problem is that it cannot be done easily. SUMMARY OF THE INVENTION Therefore, it is an object of the present invention to provide a posture teaching method that can extremely easily and accurately teach a target torch angle and a corresponding posture of the welding robot to an articulated welding robot. It is.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the main means adopted by the present invention is to attach a torch to the tip of the arm so as to be rotatable around the axis of the arm. In the method for teaching the posture of an articulated robot, the inclination angle α of the torch with respect to a reference plane including a work line, the forward movement of the torch with respect to the work line;
Three parameters are input: the receding angle β and the rotation angle γ of the wrist that grips the torch with respect to the axis of the torch, and based on these, the attitude of the torch is determined, and the data regarding the attitude of this torch and the torch This is a method for teaching the posture of a welding robot, in which each joint angle of the robot is determined based on the coordinate value of the tip of the robot.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples embodying the present invention will be described below with reference to the accompanying drawings to provide an understanding of the present invention. It should be noted that the following examples are examples of embodying the present invention, and are not intended to limit the technical scope of the present invention. Here, FIG. 1 is a system configuration diagram of a welding robot to which the posture teaching method according to an embodiment of the present invention can be applied, FIG. 2 is a schematic configuration diagram of the welding robot, and FIG. 3 is an enlarged view of the main parts of FIG. 2. 4 are explanatory diagrams showing the positional relationship between the welding torch of the welding robot and the welding line, and FIG. 5 is a flowchart showing the processing procedure in the posture teaching method. The posture teaching method according to this embodiment is realized by an offline teaching system as shown in FIG. computer 3
It is configured with a CRT 4 and the like.

The welding robot 1 has degrees of freedom in six axes and has a joint configuration as shown in FIG. θ1 to θ6 in FIG. 2 each define the joint angle of each joint, and the position vector A is the rotation center of the fourth, fifth, and sixth axes of the welding robot 1. Equivalent to.

In the welding robot 1, a wrist member 6 is provided at the tip of the arm 5 so as to be rotatable around the axis of the arm 5, and a welding torch 7 is held by the wrist member 6. In the welding torch 7, as shown in FIG. 3, the torch tip coordinates are the position vector W (W1, W
2, W3), and a position vector Q is given as a virtual torch apex at an extended position on the side opposite to the torch tip along the axis of the welding torch 7. In the welding work using the above-mentioned welding robot 1,
The welding torch 7 and the welding line L have a positional relationship as shown in FIG. In the figure, α is the inclination angle of the welding torch 7 with respect to the reference plane including the welding line L.
β represents the advancing/retreating angle of the welding torch 7 with respect to the welding line L, respectively.

[0010] Once the torch tip coordinates, the above-mentioned inclination angle α, and advance/retreat angle β are determined based on the above-mentioned preconditions, the spatial position through which the welding torch 7 passes can be determined. However, since the welding robot 1 used in this embodiment has a 6-axis configuration as described above,
The attitude of the welding robot 1 cannot be determined because one variable is missing from the values of the position vector W representing the torch tip coordinates, the inclination angle α, and the advance/retreat angle β. This is based on the fact that the position vector A representing the rotation center described above can rotate 360° relative to the axis of the welding torch 7 (determined by the position vectors W and Q).

Therefore, in this embodiment, the rotation angle γ of the wrist member 6 that grips the welding torch 7 with respect to the axis of the welding torch 7 is taken into consideration in addition to the above-mentioned parameters. Consideration has been given to making it easy for the operator to understand and arbitrarily determine the posture of the robot.

[0012] Continuing on, based on FIG. 5, the procedure of posture teaching and processing based thereon will be explained. In addition, S1, S2, ... in FIG. 5 represent each processing step, and step S1
~S7 is processed using the offline teaching system. First, in S1, the path of the tip of the welding torch 7 is taught, and the welding line L and welding direction are determined. continuation,
In S2, a desired step in which the posture of the welding torch 7 is to be taught is selected, and the inclination angle α, advance/retreat angle β, and rotation angle γ are calculated based on the current joint angles θ1 to θ6 in that step and displayed on the CRT 4. will be displayed.

Then, in S3, values to be changed and taught regarding the inclination angle α, advance/retreat angle β, and rotation angle γ are input, and the attitude of the welding torch 7 is determined based on these values. When the attitude of the welding torch 7 is determined as described above, in S4, the torch tip coordinates of the welding torch 7, the inclination angle α, the advance/retreat angle β, the rotation angle γ
Each joint angle θ1 to θ6 of the welding robot 1 is calculated from each value by inverse transformation. If necessary, it is also possible to calculate the robot posture, such as the roll, pitch, yaw angle, Euler angle, etc., from the inclination angle α, advance/retreat angle β, and rotation angle γ.

The postures of the welding robot 1 and welding torch 7 determined as described above are displayed on the CRT 4 (
S5), the operating range and the presence or absence of interference are checked (S6). The teaching data obtained as described above is then stored in the memory (S7) and saved. After that, in S8, the above teaching data is transferred to the robot control panel 2.
and the welding robot 1 is controlled. Next, the above-mentioned inverse transformation and forward transformation will be briefly explained below.

If each joint angle in the welding robot 1 shown in FIG. 2 is defined as θ1 to θ6, the spatial position of the welding torch 7 can be determined by performing coordinate transformation as shown in the following equation. Here, A is a coordinate transformation matrix, which is determined by the mechanism of the welding robot 1 and the arm length. The above matrix A is generally regular, and its inverse matrix can be obtained.

[Math 1]

From this, equation (2) can be inversely transformed as shown in the following equation, where the position vector W (W1, W2, W3) representing the torch tip coordinates of the welding torch 7, the inclination angle α, the advance/retreat angle β, If the rotation angle γ is known, each joint angle θ
1 to θ6 can be obtained.

[Math 2]

Therefore, in the system of this embodiment, the target torch angle (α, β, γ) of the welding torch 7 can be determined extremely easily and accurately without being influenced by the operator's experience or intuition.
can be taught. In this teaching method,
Unlike the case where roll, pitch, yaw angles or Euler angles are used, by inputting the angle of the welding torch 7 with respect to the welding line L, the operator can easily understand the relationship between the welding object and the welding torch 7. This improves operability. Furthermore, by considering the rotation angle γ when determining the orientation of the welding torch 7, the orientation of the welding robot 1 can be determined as desired by the operator. And, no matter what the rotation angle γ is, the direction vector of the welding torch 7 with respect to the welding line L does not change.
The teaching can be easily performed so that welding can be performed while avoiding interference with obstacles.

In the above embodiment, teaching data is created by an offline teaching system, and this teaching data is transferred to the robot control panel. It is also possible to directly teach the welding robot 1 by incorporating an algorithm as shown in advance and inputting the tilt angle α, advance/retreat angle β, and rotation angle γ from a teaching box. Furthermore,
When cutting is performed using a plasma torch instead of the welding torch 7 as described above, determining the torch posture using this algorithm is extremely effective for finishing the cut surface.

[0019]

[Effects of the Invention] As described above, the present invention provides a method for teaching the posture of a multi-jointed robot, which is equipped with a torch at the tip of an arm so as to be rotatable about the axis of the arm. An inclination angle α of the torch with respect to the reference plane including, an advancing/retreating angle β of the torch with respect to the working line, and a rotation angle γ of the wrist gripping the torch with respect to the axis of the torch.
The three parameters are input, and the posture of the torch is determined based on these, and each joint angle of the robot is determined based on the data regarding the posture of the torch and the coordinate value of the tip of the torch. Since this robot posture teaching method is characterized by the following, it is possible to very easily and accurately teach a target torch angle and a corresponding robot posture to an articulated robot.

[Brief explanation of the drawing]

FIG. 1 is a system configuration diagram of a welding robot to which a posture teaching method according to an embodiment of the present invention can be applied.

FIG. 2 is a schematic configuration diagram of the welding robot described above.

[Figure 3] An enlarged view of the main parts in Figure 2.

FIG. 4 is an explanatory diagram showing the positional relationship between the welding torch of the welding robot and the welding line.

FIG. 5 is a flowchart showing a processing procedure in the posture teaching method.

[Explanation of symbols]

1...Welding robot 2...Robot control panel 3...Personal computer 4...CRT
5...Arm 6...Wrist member
7...Welding torch L...Welding line
O...Reference plane θ1 ~ θ6
…Joint angle α…Inclination angle β…Advance/retreat angle γ…Rotation angle S1 to S8…Processing step

Claims (1)

[Claims] Claim 1. A posture teaching method for a multi-jointed robot comprising a torch provided at the tip of an arm so as to be rotatable about the axis of the arm, wherein the inclination angle of the torch with respect to a reference plane including a work line is provided. Input three parameters: α, advance/retreat angle β of the torch with respect to the work line, and rotation angle γ of the wrist gripping the torch with respect to the axis of the torch, and determine the attitude of the torch based on these parameters. A method for teaching a robot posture, characterized in that each joint angle of the robot is determined based on the data regarding the posture of the torch and the coordinate value of the tip of the torch.