JPH0118442B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a teaching method for an industrial robot, and more particularly to a teaching method for operating a robot arm using a teaching box in an articulated robot that performs PTP teaching CP playback control.

What defines the robot's posture is the angle formed by each axis of the robot. For example, in an articulated robot with five degrees of freedom (S1, S2, S3, S4, S5) as shown in Figure 1a, there is a rotatable turntable 2 mounted on a fixed base 1, and a A lower arm 3 having one end fixed and extending upward, an upper arm 4 connected at the upper end of the lower arm 3, and a wrist portion 5 provided at the tip of the upper arm 4. Angle θ ₁ based on the inclination of the lower arm 3, Angle θ ₂ based on the inclination of the lower arm 3, Angle θ ₃ formed by the upper arm 4 and lower arm 3, Angle θ ₄ based on the vertical bending of the wrist portion 5, and Rotation of the wrist portion 5 The structure allows each of the angles θ ₅ to be independently manipulated. This independent operation is performed by a drive unit 6 (including a servo motor and a hydraulic motor) provided corresponding to each axis in response to an operation command from a control panel.

However, it is difficult for a person who teaches the robot the motion path points to decide how to define the angle and what kind of posture the robot will take. Therefore, it is usually fixed to the robot.
An XYZ coordinate system (reference coordinate system) is used, and the position data of the robot is subjected to coordinate conversion processing (computer software processing) by the calculation/control means to calculate the angles θ ₁ to _{θ 5} . This calculation
All processing in the control means and data in the storage means are data based on the XYZ coordinate system.

In the XYZ coordinate system, the connection point between the turntable 2 and the lower arm 3 is the origin 0, the Z axis is the upward direction from the fixed fixed position of the base 1, and the initial posture of the robot is shown in the plan view of Fig. 1b. The direction in which the upper arm 4 is facing when viewed from above (the direction in which the workpiece 10
The Y axis is defined as the direction perpendicular to the Y axis, and the X axis _is defined as _the direction perpendicular to the Y axis in a plane. Actions are being taken.

By the way, conventionally, a teaching box as shown in FIG. 3 has been used for teaching.
That is, 20 is an operation unit for positioning each axis of the robot, 21 is a toggle switch for moving in the X-axis direction, 22 is a toggle switch for moving in the Y-axis direction, and 23 is a Z-axis movement unit.
This is a toggle switch for moving in the axial direction. Further, 24 is a switch for moving the wrist portion 5 up and down, and 25 is a switch for rotating it left and right. However, as shown in FIG. 2, when the workpiece 10 is located almost in front of the robot, the operator must
It is easy to distinguish between Y and Z moving directions, but workpiece 1
1. When the workpiece 12 is located diagonally to the robot, it is confusing how to move and operate it in the O, Y, and Z directions.
This is especially true when the operator is close to the workpieces 11 and 12 while visually checking the route to be taught.

Therefore, an object of the present invention is to provide a teaching method that allows an operator to easily and accurately determine the direction of robot movement no matter where the workpiece is placed within the robot's operating range. Moreover, it is possible to use a conventional teaching box as is. In order to achieve the above object, the present invention provides a teaching method for an articulated robot that performs PTP teaching and CP playback control by operating a switch on a teaching box. This standard is based on a coordinate system in which the first axis is the intersection of the plane formed by the axis of the arm and the horizontal plane, and the second axis is the direction perpendicular to the first axis on the horizontal plane. While setting the target position in the coordinate system, rotate the robot around the vertical axis by operating the switch on the teaching box.
A second coordinate system is defined in which the first axis is the intersection of the plane formed by the axis of the book arm and the horizontal plane, and the second axis is the direction perpendicular to the first axis on the horizontal plane. Then, the first and second coordinates of this second coordinate system are
The robot is moved by operating the switch on the teaching box with reference to the axis of The position of the robot after movement is determined on the reference coordinate system using the quantity, and by repeating this process as necessary, the target position of the robot on the reference coordinate system is taught. The present invention provides an industrial robot teaching method with characteristics.

Examples will be explained below.

The teaching box 30 used in the method of one embodiment is a conventional operating section 20, as shown in FIG.
The display is "Right" for "X", "Left" for "-X", "Front" for "Y", "Rear" for "-Y", and "Rear" for "Z". It is used by rewriting ``upper'' and ``-Z'' as ``lower.'' This is to make it easier to see when operating, and there is no difference in functionality from the previous version.If you push the toggle switch from the neutral position to the "right" position, for example,
Command signals are simply output from the teaching box to the control panel via a specific path.
The control means of the control panel performs predetermined operations based on this command signal. The control means includes a computer, preferably a microprocessor or microcomputer. The control means uses a constant positioning control cycle Tc (for example, Tc = 20ms) in response to the movement command.
unit movement amount (Δx,
Δy, Δz). For example, in the conventional example, from point P (xp, yp, zp) in FIG.
When moving in the axial direction (turn switch 21 in Fig. 3 to "X"), after Tc, point P'' (xp + Δx, yp,
zp), and if you keep pushing it to the "X" side, after n control cycles,
It can be moved to the position of point P'' (xp+nΔx, yp, zp).

However, in the method of the present invention, as shown in the teaching procedure in FIG. 6, the current position of the robot is first read in step S1. Assuming that the robot has been turned by an angle θ on the horizontal plane to the turning position shown by the virtual line, read this angle θ, and then move the arms 3 and 4.
The direction in which the arms are facing, more precisely arms 3 and 4
The intersection line between the plane formed by the axis of and the horizontal plane is the Y′ axis,
The axis perpendicular to this on the horizontal plane is defined as the X′ axis, and X′,
A second coordinate system Y', Z is set in step S2, and then, in step S3, based on this second coordinate system, that is, the X' axis of the second coordinate system,
By operating each switch on the teaching box with the Y' axis as a reference, the robot moves according to the X'Y'Z coordinate system. That is, for example, when the switch 31 of the teaching box shown in FIG. 4 is turned "right", the robot is moved in the positive direction of the X' axis. Therefore, in that case, it is moved by Δx in the positive direction of the X' axis every cycle Tc of control. In terms of the reference coordinate system (XYZ system), this amount of movement corresponds to Δxcosθ in the X-axis direction and Δxsinθ in the Y-axis direction, assuming that the angle between the Y-axis and the Y'-axis is θ. do. Therefore, after n cycles, if the point is moved from point P to point P' as shown in Figure 5, if the coordinates of point P in the reference coordinate system are (xp, yp, zp), then The coordinates of ′ in the reference coordinate system are (x′p=xp+n・Δxcosθ, y′p=yp+n・
Δxsinθ, z′p=zp). More generally, the robot is
The robot is operated along the X' and Y' axes, and the position of the robot in the XYZ coordinate system after the operation can be found by converting the position in the X'Y'Z coordinate system using the above angle θ. can.

If point P' is the desired target position to be taught (YES in step S4), the user may press the setting button on the teaching box in step S5. When the setting button is operated, the robot's current
The position on the XYZ coordinate system is determined by the above calculation, and the point on the XYZ coordinate system is determined in step S7.
The coordinate values of P′ are stored. And step S8
When it is determined that teaching has finished,
Finish teaching.

On the other hand, if point P' is not the target position (NO in step S4), a temporary coordinate system at that robot position is set again, and teaching is performed to move the robot to the target position based on this temporary coordinate system. All you have to do is operate the switch on the box.

As described above, in the method of the present invention, by always operating the robot in either the left, right, up, or down direction based on the rotation position of the robot arm, the robot can quickly and easily get to the target position to be taught. The target position can be reached without any trouble, and the obtained target position is set as a position (coordinates) in the reference coordinate system by coordinate transformation. Since all angles corresponding to the five degrees of freedom, including this angle θ, are always input to the control means by the position detector as an internal measurement function, the control means can use this position data at any time. Therefore, when the switch is pushed to the "right", the angle θ is latched,
This value of θ can be held until the switch output disappears and used in internal calculations. If the target position of the XYZ coordinate system is set by the above internal calculation process, it will be changed to the target value of the arm angle system for CP control during playback, and the servo control will be performed using the data of this arm angle system as the target value. ,
There is no difference from normal robot control.

In other words, the actual teaching operation can be performed based on the X'Y'Z coordinate system at that time, and position control is executed on the robot side based on the XYZ coordinate system.

In short, when operating the operating section 30 of the teaching box, the unit increment for each positioning control cycle Tc is
When commanded "right", it is converted to move Δxcoθ in the X-axis direction and Δxsinθ in the Y-axis direction on the reference coordinate system, and when commanded "left", it moves Δxcos (θ + π) in the X-axis direction, It is converted to move by Δxsin (θ+π) in the Y-axis direction. Also, if "front" is commanded, it is converted into Δycos (θ+π/2) in the X-axis direction and Δysin (θ+π/2) in the Y-axis direction, and if "back" is commanded, Δycos (θ+π/2) is converted in the X-axis direction. Δysin (θ+3π/2) in the Y-axis direction. The "up" and "down" directions are the same as before.
Note that θ here is a radian angle.

Such calculations are set in advance in the computer program, and are executed by the control/calculation means immediately performing calculation processing based on the switch command input. Such a program can be easily designed by a person skilled in the art and can be easily incorporated into a robot control system.

As described above, according to the present invention, the direction in which the arm of the multi-jointed robot is directed is used as a temporary reference, and the teaching box is operated from that position forward and backward and left and right, so that the workpiece can be moved in any direction. Even in such a position, the operator can easily and accurately determine the direction of movement of the robot without any confusion.

Furthermore, since the conventional teaching box can be used as is, it does not increase costs and contributes to improving cost performance.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an articulated robot, in which a is a side view and b is a plan view. Fig. 2 is an explanatory diagram of the position of the workpiece relative to the robot, Fig. 3 is an external view of a conventional teaching box, Fig. 4 is an external view of a teaching box applied to an embodiment method of the present invention, and Fig. 5 is an external view of the teaching box. FIG. 6 is a flowchart showing the teaching box procedure according to the present invention. 2... Turntable, 3... Lower arm, 4...
...Upper arm, 30...Teaching box positioning operation section, 31...Toggle switch in the left and right direction, 32...Toggle switch in the front and back direction.

Claims (1)

[Claims] 1 Operate the switch on the teaching box
PTP teaching A method for teaching an articulated robot that performs CP playback control, in which the first axis is the intersection line of the horizontal plane and the plane formed by the axes of the two arms of the robot at the robot's reference position. On the above horizontal plane, this first
A coordinate system whose second axis is perpendicular to the axis of The first axis is the intersection line between the horizontal plane and the plane formed by the axes of the two arms of the robot in the rotated position, and the second axis is the direction perpendicular to the first axis on the horizontal plane. Define a second coordinate system, and operate the robot by operating the switch on the teaching box based on the first and second axes of the second coordinate system.
and the relative angle between the coordinate system of and the reference coordinate system, and the second
The position of the robot after movement is determined on the reference coordinate system using the direction and amount of movement on the coordinate system, and by repeating this process as necessary, the robot's position on the reference coordinate system is determined. A teaching method for an industrial robot, characterized in that a target position is taught.