JPH0379284A - Control method for industrial robot - Google Patents

Abstract

PURPOSE:To teach the motion locus of a robot quickly and easily by inputting the information of the position and direction where a robot hand is moved after fixing the movement of the shafts which are selected optionally in the number exceeding six axes and storing the moving locus of six axes only. CONSTITUTION:The key operation of a pendant 20 is performed by selecting two axes to be fixed from the positional relation of the moving locus of a welding gun 16 and a work necessary for welding after setting to a teach mode by the mode key of the pendant 20. When the information of the position where the welding gun 16 is to be moved in order in this state is input by the pendant 20, the movement of each axis to be moved to the position thereof is operated inside a control part 21 and each axis is moved by the specific quantity. This moving position is confirmed and the value thereof is stored. In order to operate and control the robot thus teached just like that, a playback operation is executed by a mode key. Consequently the welding gun 16 is subjected to CP control and moved to the specific position in the specific order.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an industrial robot control method for controlling the operation of an industrial robot having a motion function over six axes.

(Prior Art) Industrial robots are widely used for workpiece spot welding work, workpiece clamping work, etc.

For example, when performing welding work using an industrial robot, a spot welding gun is attached to the robot's hand.
This welding gun is used to weld workpieces such as automobile bodies. In this case, the tip of the welding gun is
It is necessary to control the linear position in the three axis directions of x, y, and z, and the direction, that is, the posture of the welding gun by rotating it around the three axes. Therefore, if the robot has a total of six axes of motion, three axes for position and three axes for direction, it will be possible to perform normal tasks.

When performing welding work using a robot with such a six-axis motion function, a teach box called a pendant is used to move the position of the welding gun at the tip of the robot hand. When welding workpieces by teaching the moving position and direction, the welding gun draws the trajectory as taught. During this teaching operation, position information and direction information for moving the welding gun from one position to another are manually provided by operating keys provided on the pendant. When this information is input, the CP determines how much each drive source such as a motor should be operated to achieve the motor function of each of the six axes.
A control unit having U, etc. makes a judgment and controls each for a predetermined time or distance, and when the memory key is operated, the respective values are stored in the storage medium.

By the way, in industrial robots that perform welding work, etc., the operating position or direction of the welding gun is made to operate in a more complex manner, and in order to achieve more advanced control, seven axes or Industrial robots having motion functions with more than six axes, such as eight axes, have been developed. In this way, in order to teach the movement trajectory of a welding gun installed on an industrial robot that has a motion function exceeding six axes, and to reproduce the movement of the welding gun according to the trajectory, it is necessary to In order to move from one position to the next, simply using a pendant to manually input position and direction information cannot teach the information.

The reason for this is that in order to regulate a certain position and direction, if the robot has a movement function with 7 or 8 axes, it is possible to control which axis to operate and set the position and direction. This is because an infinite number of solutions will be required to determine the position or direction of movement of each axis.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to make it possible to easily teach the locus of movement of an industrial robot having a motion function exceeding six axes, and to make it possible to easily control such a robot.

(Means for Solving the Problems) To achieve the above object, the present invention provides a method for controlling an industrial robot, which teaches the movement trajectory of a robot hand of an industrial robot having a motion function exceeding six axes. Therefore, after selecting an arbitrary axis exceeding six axes and fixing the movement of the axis, manually input information on the position and direction in which the robot hand moves, and memorize the movement trajectory of only the six axes. This is a control method for an industrial robot in which the robot is taught by

(Function) When teaching the moving position and direction of the hand of an industrial robot that has a motion function with more than 6 axes, if predetermined position information is input, the operating positions of all the axes can be specified. However, in the present invention, any axis exceeding six axes is selected, that axis is fixed, and the operating position and orientation are determined for each of the remaining at least six axes. This makes it possible to teach the position of each axis quickly and reliably.

(Embodiment) FIG. 1 is a diagram showing an industrial robot embodying a method for controlling an industrial robot according to an embodiment of the present invention.

This robot is a welding robot used to assemble automobile bodies, and has eight-axis movement functions. This robot has a rotary table 10 that rotates in the direction of θ1 around a vertical axis.
A first arm 11 consisting of two mutually parallel arm members 11a111b is attached to the rotary table 10 so as to be freely rotatable in the direction of θ2 about a horizontal axis. A second arm 12 is attached to the tip of the first arm 11 so as to be rotatable in the direction of θ3. This is achieved by driving the connecting arms llc which interconnect the lower ends. This second arm 12 has a cylindrical main body 12a and a sliding arm portion 12b that is rotatable in the direction of θ4 within the cylindrical main body 12a.

At the tip of the sliding arm portion 12b of this second arm 12,
A third arm 13 is attached rotatably in the direction of θ5(1), and a fourth arm 1 is further attached to the tip of the third arm 13.
4 is attached rotatably in the direction of θ5(2).

These arms 13 and 14 are rotated in the directions of θ5(1) and θ5(2) described above in synchronization by the same drive source, so they collectively have one axis motion function θ.
It is recognized that 5 is H.

A hand body 15 is attached to the tip of the fourth arm 14, and the hand body 15 rotates in the direction θ6 about its central axis, and the hand body 15 rotates in the direction θ7, which is perpendicular to the rotation direction θ6. It also rotates. This hand body 15 has the above-mentioned turning directions θ6 and θ7.
A spot welding gun 16 is mounted as a robot hand so as to be able to freely rotate in a direction θ8 perpendicular to either direction.

As described above, the illustrated robot has eight axis movement functions indicated by the symbols θl to θ8.

Therefore, with such an axial motion function, the welding gun, that is, the robot hand 16, can move in a complex motion trajectory, and can perform complex three-dimensional movements such as welding automobile bodies. This makes it possible to fully handle welding work that requires.

However, as mentioned above, in order to control the movement trajectory of the welding gun 16 and to teach it, even if the welding gun 16 is set at a certain position and the position is memorized, it is necessary to move eight axes. If it has a function, there are an infinite number of values that satisfy the stopping position of each axis for setting the position, so it becomes impossible to calculate each position.

In the present invention, when performing a teaching operation, two axes of the robot, which has a total of eight axes movement functions, are selected, these two axes are fixed so as not to move, and the remaining six axes are fixed so as not to move. The operating position of each axis is taught.

This teaching operation is performed by a pendant or teach box 20 shown in FIG. Data manually input by operating this pendant 20 is sent to a control unit 21 connected to the robot.
The operating position of each axis is calculated, and the calculated values are stored in the storage section.

This pendant 20 is the same as the conventional pendant except that it has keys for selecting any two axes out of the eight axes in order to stop the movement of the two axes. Therefore, in order to teach the movement locus of the welding gun of this robot, after turning on the power switch provided on the operation panel (not shown), the start key is pressed. At this time, if the welding gun 16 is not at the original position, that is, the home position, it is moved to a predetermined original position. Then, after setting the teach mode using the mode key of the pendant 20, select two axes to be fixed based on the positional relationship between the movement locus of the welding gun 16 required for welding and the workpiece, and press the keys on the pendant 20. Let's do it. In this state, when information on the positions to which the welding guns 16 should be sequentially moved is manually input using the pendant 20, the amount of movement of each axis to reach that position is calculated in the control unit 21, and each axis is moved to a predetermined position. It will move by the amount. This movement position will be confirmed and its value will be stored.

In order to control the operation of the robot that has been taught in this manner, a playback operation must be performed using the mode key. As a result, the welding gun 16
P sub-control, it moves to a predetermined position in a predetermined order.

As shown in FIG. 1, a welding gun 16 is used when a robot having an eight-axis motion function performs welding work using the welding gun 16 for assembling an automobile body.
An example of the movement locus is shown in Fig. 2. In this case, the welding gun 16 is inserted into the interior of the car body to weld the flow panel part of the car body, and the welding gun 16 is inserted into the side window formed on the side of the car body. It will be entered from the part corresponding to . Therefore, in Fig. 2, the obstacle 3
0 corresponds to the body side part of the automobile body.

FIG. 2 schematically shows the change in the position of the robot when the welding gun 16 is moved from the position indicated by the symbol A to the position indicated by the symbol B. In FIG.

At the position indicated by the symbol A, the position or posture of the welding robot is shown by a solid line.

In this state, only the axes θ2, θ3, and θ5 are operated,
When the robot is operated to the position shown by the broken line, the arm member 11b of the first arm 11 will interfere with the obstacle 30, that is, the body side of the automobile body. Therefore,
First, at least two axes other than these axes θ2, θ3, and θ5 are fixed, and the first arm 11 is operated.
After rotating to the position shown by the dashed line, the axis θ2 and at least one other axis are fixed, and the axes θ3 and θ7 are actuated to move to the position shown by the two-dot chain line.

In this way, interference between the obstacle 30 and the robot can be avoided, and desired welding work can be reliably performed even in a narrow space.

In the illustrated embodiment, the control method of the present invention is applied to a welding robot, but the present invention can also be used to control various types of industrial robots such as robots for clamping work. It is possible to achieve this.

Further, the present invention can be applied to any industrial robot having a movement function of 7 to 9I or more axes.

(Effects of the Invention) As stated above, the present invention provides a method for controlling an industrial robot, which teaches the movement locus of the robot hand of an industrial robot that performs more than six motor functions. After selecting an arbitrary number of axes exceeding six axes and fixing the movement of the axes, the robot hand inputs information on the position and direction in which the robot hand moves, and stores the movement trajectory of only the six axes. This allows the robot to be taught the robot's operating trajectory quickly and easily, and it is also possible to play back the taught trajectory, making it easier to control the robot. It became possible to do it easily.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an industrial robot embodying the industrial robot control method of the present invention, and FIG. 2 is a schematic diagram showing the operating state of the robot shown in FIG. 1. 10... Turntable, 11-14... Arm, 15...
- Hand body, 16... Welding gun, 20... Pendant, 30... Obstacle.

Claims (1)

[Claims] A control method for an industrial robot that teaches the movement locus of a robot hand of an industrial robot having a motion function of more than six axes, the method comprising selecting an arbitrary number of axes more than six axes and moving the relevant axis. After fixing the robot hand, enter information on the position and direction in which the robot hand will move, and
A control method for an industrial robot that teaches the robot by memorizing the movement trajectory of only the axes.