JPH0823766B2 - Robot teaching method - Google Patents

Description

The present invention relates to a robot teaching method for teaching a robot the position and orientation information of an end effector on the surface of a work.

[Conventional technology and its problems]

As a cutting robot capable of cutting a work having a complicated three-dimensional shape such as a press-formed sheet metal into a desired shape, the present applicant has filed an application,
Various types such as the plasma cutting robot disclosed in JP-A-57-96791 have already been proposed and put into practical use.

In such a robot, in order to teach the cutting line to the robot, it is necessary to previously teach the robot, as teaching data, information on a predetermined position on a work or a teaching model.

Then, as a method of creating such teaching data, NC created by a control device of another NC machine tool, etc.
There is a method in which the end effector of the robot is moved based on the data, and the operator adjusts and sets the teaching data not included in the NC data.

FIG. 8 is an explanatory diagram showing a teaching data creating method using such NC data. In the figure, a cutting line C and a teaching point P are provided on the surface of the work W having a three-dimensional shape.
_{i-1 to} P _{i + 2} are virtually provided. Since these teaching points are simple, the distance between them is larger than the actual distance. The NC data is two-dimensional data of X axis and Y axis, and NC data points Q _{i-1 to} Q _{i + 2} and NC data line D on the XY surface specified by the NC data are located above the work W. It is shown. The NC data line D is set on the XY plane at the Z coordinate position sufficiently high with respect to the work W so that the torch T of the robot and the work W do not interfere with each other.

The cutting line C is a projection of the NC data curve D on the work W, and the NC data points Q _{i-1 to} Q _{i + 2} and the teaching points P _{i-1 to} P _{i + 2} correspond to each other. .

Further, in the figure, a torch T as an end effector of the robot and a schematic movement path R of the torch T are also shown.

To create teaching data by the conventional method, first set the torch T to the first NC data point Q _i-1 based on the NC data.
Automatically move to. At this time, the torch T takes a constant (for example, vertically downward) posture. next,
Switch to the manual mode and move the torch T to the teaching point on the work W.
It is lowered to P _i-1, to adjust the Z-coordinate position and orientation of the torch T in the teaching point P _i-1, to create a teaching data by storing in the robot as a teaching point information.

After the teaching data of the teaching point P _i-1 is created, the mode is switched to the automatic mode, the torch T is automatically moved to the position of the next NC data point Q _i , and its attitude is corrected vertically downward.
In this case the next teaching point from the first teaching point P _i-1 torch T P _i
The teaching data possessed by the robot at this point is NC data points Q _{i-1 to} Q _{i + 2.}
This is because there is no data that defines the Z coordinate and the attitude of the torch T. The movement of the torch T from the NC data point Q _i to the teaching point P _i is switched to the manual mode as described above, and the torch T is manually brought close to the teaching point P _i to adjust the Z coordinate position and attitude of the torch T. , And then
Teaching data is created by storing the teaching point information in the robot.

As described above, conventionally, the torch T is automatically moved to the corresponding NC data points Q _{i-1 to} Q _{i + 2} once for each teaching point P _{i-1 to} P _{i + 2} , and then the torch T is manually operated. Teaching data was created by moving T to adjust the Z coordinate position and posture.

At this time, the attitude of the torch T is adjusted by rotating the rotary shaft around the torch T, so that, for example, from the teaching point P _i to the next NC
When the torch T is automatically moved to the data point Q _{i + 1} , the rotation axis around the torch T is also automatically rotated to return the torch T to a fixed posture (vertically downward). However, since this movement is performed automatically, there is a risk that the torch T collides with the work W depending on the rotation method of the torch T, the movement path, and the shape of the work W. Further, depending on the torch postures at the teaching points P _{i-1 to} P _{i + 2,} there is a problem that the torch T makes an abrupt movement as the torch T returns to the vertically downward posture, which is particularly dangerous. It was

Also, since the teaching points (for example, P _i-1 and P _i ) that are adjacent to each other have similar coordinate positions and torch postures, if the torch T is moved sequentially with respect to the neighboring teaching points, the torch T It is also easy to adjust the position and posture of the. However, the teaching data is limited (in the above case,
Since the torch T is moved based on the data (X-axis and Y-axis only), the torch T is temporarily moved to the NC data point for each teaching point P _{i-1 to} P _{i + 2.}
Q _{i-1 to} Q _{i + 2} . Therefore, there is a problem that it takes time and time to adjust the torch T to a desired position and posture for each teaching point, and teaching data cannot be efficiently created.

[Object of the Invention]

The present invention has been made to solve the problems as described above, and when performing teaching based on coordinate data for only predetermined degrees of freedom created in advance by another data creating means such as NC data. The present invention provides a teaching method for a robot, which does not have a risk of collision between an end effector and a work due to automatic movement of the end effector, and can perform teaching related to a large number of teaching points.

[Means for achieving the purpose]

In order to achieve the above-mentioned object, the present invention teaches the movement of an endon effector of a robot on the surface of a work, and teaches coordinate data of only some of the degrees of freedom created in advance by a predetermined data creating means. A method of teaching the robot by using (a), the mutual positional relationship between the surface of the workpiece and the end effector is detected by mutual position detecting means included in the robot, and based on the detection result. While maintaining the mutual positional relationship between the surface of the work and the end effector in a predetermined relationship, the movement control means is used to move the end effector to the location indicated by the teaching point coordinate data, and (b) the movement. After or after moving the end effector to the desired position, move the position of the end effector. Captures the information and attitude information,
(C) The above processes (a) and (b) are repeated to advance the teaching.

〔Example〕

A. Outline of Configuration of Embodiment FIG. 1 is a schematic perspective view showing a mechanical configuration of a Cartesian laser cutting robot as an example of a robot to which the present invention is applied to perform teaching. In FIG. 1, the laser cutting robot RB has a movable base 2 which is movable on the base ₁ in the X direction (horizontal direction) by a motor M ₁ (not shown). A work (not shown) is placed. A beam 4 is installed on the top of a column 3 which is vertically erected on both sides of the base 1.
The beam 4 is provided with a moving column 5 extending in the Z direction (vertical direction) in the figure and movable in the Y direction by the motor M ₂ .

Further, a motor M _{4 which} moves up and down in the Z direction by the motor M ₃ is provided at the lower end of the moving column 5. Accordingly, the arm 6 provided at a position eccentric from the center axis of the moving column 5 rotates in the θ direction in the drawing. Further, a motor M ₅ is provided on the lower side of the arm 6,
This allows the laser torch T as an end effector.
Rotates in the ψ direction in the figure. Furthermore, this laser torch T
A height sensor HS (to be described later) that detects the distance between the laser torch T and the surface of the work W is formed by utilizing.

The laser beam from the laser oscillator 7 is applied to the laser torch T through the laser guide pipe 8. The control device 9 has a torch distance detector, a microcomputer, and the like, which will be described later, built therein, and the operation panel 10 has a keyboard, a display, and the like. Further, the external computer 11 is for performing input / output of various data and data processing, and includes a CRT 12, a keyboard 13, and the like.

FIG. 2 is a schematic diagram of an electrical configuration of the robot RB shown in FIG. In FIG. 2, a microcomputer 21 built into the control device 9 is connected with the following devices via a bus BL.

The motor M ₁ ~M ₅ and, (not shown in FIG. 1) encoder E ₁ to E ₅ for detecting the rotation angle of the motor M ₁ ~M ₅
Laser drive device 7 Operation panel 10 External computer 11 Laser beam is supplied from the laser oscillator device 7 to the laser torch T, and a laser beam torch is generated by using a height sensor HS provided at the tip of the laser torch T. The relative distance between T and the work W is detected by the torch distance detection device 22, and the data indicating the relative distance is given to the microcomputer 21. This system can be operated under the control of a host system (not shown).

B. Detailed Structure of Laser Torch T FIG. 3 is a partial cross-sectional view showing details of the laser torch T described above. In the figure, the lower portion of the cylindrical housing 40 of the laser torch T serves as a nozzle tip 41 whose inner and outer diameters are reduced in a conical shape toward a torch hole 43 at the lower end thereof. An outer peripheral portion of the nozzle tip 41 in the torch hole 43 portion is a height sensor HS having a large plane area facing the work W. In addition, the lens inside the housing 40
42 is provided, and the laser beam LB provided from the laser oscillation device 7 is focused by the lens 42 and is applied to the work W.

When the laser torch T is aimed at the work W, the height sensor HS has a clearance h between the work W and the nozzle tip 41.
Is a sensor that detects a difference between the two by a change in capacitance. That is, with respect to a predetermined relative distance between the laser torch T and the work W, the capacitance increases when they approach each other,
Conversely, when they are separated from each other, the capacitance decreases. Therefore, if the laser torch T and the arm 6 are electrically insulated and the electrostatic capacitance of the height sensor HS is detected by the torch distance detection device 23 shown in FIG. 2, the actual relative relation between the laser torch T and the work W is obtained. It is possible to determine whether the target distance is smaller or larger than the preset relative distance.

In the present invention, the microcomputer 21 controls the operation of the laser torch T so that the relative distance between the laser torch T and the work W is always constant based on the detection data by the height sensor HS.

C. Structure of teaching data As described above, the laser cutting robot RB is a five-axis robot having three axes (X, Y, Z) in the Cartesian coordinate system as degrees of freedom and two axes (θ, ψ) as rotation around the laser torch T. However, in many cases, only 2-axis (X, Y) or 3-axis (X, Y, Z) of the Cartesian coordinate system is obtained as NC data.

Therefore, first, the data structure when the final teaching data is created from the NC data will be described.

Fig. 4 shows the difference in data structure from NC data to teaching data. In the figure,
As NC data, biaxial data of x _i and y _i are obtained (Fig. 4 (a)). Here, the subscript i indicates that it is data for each teaching point. In the embodiment according to the present invention, the operation mode of the robot RB for creating teaching data is called "scanning mode". FIG. 4B shows the structure of the copying mode data given to the robot RB in the copying mode. As the scanning mode data, NC data (x _i , y _i ) is used as it is as X-axis and Y-axis data (X _i , Y _i ). The Z-axis data (Z _i ) is determined by keeping the relative distance between the laser torch T and the work W constant by the height sensor HS described above.

Rotation axis data (θ _i , ψ _i ) around the laser torch T
Is determined by the operator appropriately adjusting the attitude of the laser torch T at each teaching point. However, when the laser torch T is automatically moved from one teaching point to the next teaching point, these rotation axis data are kept constant. Therefore, in FIG. 4B, θ _i = θ _i−1 and ψ
_i = ψ _i−1 (i indicates the order of teaching points).
Further, it is necessary to specify the moving speed data V _i in order to define the operation of the laser torch T during teaching, but in the copying mode, this is set to a constant and relatively slow speed V ₀ . .

In the scanning mode, the laser torch T is automatically moved based on the 5-axis data (X _i , Y _i , Z _i , θ _i , ψ _i ) and velocity data V _i created as described above, and each teaching point is moved. At the operator, the posture of the laser torch T (that is, the rotation axes θ _i , ψ
By adjusting _i ), 5-axis data for each teaching point is created as teaching data. Fourth
FIG. (C) shows the final teaching data structure. In addition to the data of the five axes created in the scanning mode, the speed data V _i for reproduction operation is an appropriate value for each teaching point. Is newly set, and other teaching data S _i including data such as laser on / off is set for each teaching point.

Next, a method of creating teaching data in the copying mode will be described.

D. Teaching Data Creating Method in Copying Mode FIG. 5 is an explanatory diagram showing a teaching data creating method in the copying mode according to the embodiment of the present invention. In the figure, the workpiece W, the cutting line C, and the teaching point P _i-1 on the cutting line C
.About.P _{i + 2} , NC data points Q _{i-1 to} Q _{i + 2} and NC data line D are the same as those in the conventional teaching data creating method shown in FIG. Note that the NC data (x _i , y _i ) is defined by the NC data points Q _{i-1 to} Q _{i + 2} and the NC data line D on the XY plane that connects them, and the teaching point P _{i- 1 to} P _{i + 2} are NC data points Q _{i-1 to} Q _{i + 2} projected on the surface of the work W,
The cutting line C is a projection of the NC data line D on the surface of the work W.

FIG. 6 is a flow chart showing a procedure for creating teaching data of each teaching point P _{i-1 to} P _{i + 2} in order to teach the operation of the robot RB under the situation of FIG.

First, in step S1, coordinate data for some degrees of freedom of the robot RB is taught for each of the teaching points P _{i-1 to} P _{i + 2} . However, in the embodiment of the present invention, it is assumed that this coordinate data is given by NC data.
The coordinate data given here is the coordinate data of two axes (x _i , y
_i ) only.

Next, the test mode shown in step S2 is entered. The test mode is a mode for processing the created coordinate data. In step S21 in the test mode, the copy mode or the correction mode is selected. This correction mode is
This is a normal correction mode in which the end effector is moved according to the completed teaching data and a correction is made to this, and its description is omitted because it is not related to the features of the present invention.

When the scanning mode is selected, in the next step S22, the laser torch T is automatically moved to the starting point (point Q _{i-1 in} the example of FIG. 5) designated by the NC data. At this time, only the NC data (x _i-1 , y _i-1 ) is used and the laser torch T
In order not to interfere with the work W, the Z coordinate position is set sufficiently high. Further, the posture of the laser torch T does not need to be specified in particular, but is set to be vertically downward here.

Next, in step S23, the laser torch T slowly descends downward, and stops when the relative distance between the laser torch T and the work w reaches a preset constant value. This is automatically performed by using the height sensor HS described above, and as a result, the X, Y, Z coordinates of the torch T with respect to the teaching point P _i-1 on the work W match the desired values. The laser torch T is positioned at.

In this case, the laser torch T X, Y, Z
The coordinates are controlled so as to be processed as X, Y, and Z coordinates of a focus position where the laser beam LB is focused by the lens 42 and focused, and this focus position (corresponding to a working point Cp described later)
The laser torch T is positioned so that the X, Y, and Z coordinate positions of the above coincide with desired values with respect to the teaching point P _i-1 .

Next, in step S24, the X,
The operator manually adjusts only the attitude of the laser torch T without changing the Y and Z coordinate positions to correct the θ axis and ψ axis data. In this case, the laser torch T is the X, Y, Z
The posture around the coordinate position will be corrected.

After the posture of the laser torch T is corrected, the data of the 5 axes thus set is taught to the robot RB as teaching data in step S25.

The above is the teaching data creating method for the first teaching point P _i−1 , but the present invention is particularly characterized in the teaching data creating method for the second teaching point and thereafter. That is, in order to move the laser torch T to the next teaching point P _i , NC data (x _i , y _i ) is used as the coordinate data of the X axis and the Y axis, as shown in FIG. 4 (b). Further, the Z-axis is set at a constant distance from the work W by the height sensor HS. Further, the rotation axis data θ _i , ψ _i of the laser torch T is the rotation axis data θ at the teaching point immediately before.
_i-1 and ψ _i-1 are used. The moving speed V _i of the laser torch T is set to a slow constant speed V ₀ .

In step S26, based on the scanning mode data set in this way, the laser torch T is moved by the microcomputer 21 and is moved along the vicinity of the surface of the work W from the previous teaching point P _i-1 to the next teaching point P _i. Move to. The control of the Z coordinate position using the height sensor HS is performed as shown in FIG. 7 so that the working point Cp of the laser torch T is at a predetermined depth position with respect to the surface of the work W.
It is performed by changing only the Z coordinate position of the laser torch T while keeping the distance between the workpiece W and the work W at a constant value h. Therefore, the working point Cp of the laser torch T is set by the action of the height sensor HS while holding the X-axis and Y-axis coordinate data defined by the NC data. In this manner, the laser torch T and the work W maintain a constant distance h, and the laser torch T slowly moves along the surface of the work W from the teaching point P _i-1 to the teaching point P _{i at the} speed V ₀ .

In step S27, the attitude of the laser torch T at the teaching point P _i is manually adjusted, and in step S28, the coordinate data of the set 5 axes is taught to the robot RB as teaching data.

In the next step S29, it is determined whether or not all the teaching points have finished. If not, the process returns to step S26 to continue the creation of teaching data at the next teaching point.

When the teaching is advanced by repeating the above process and all teaching points are completed, the speed V _i of the laser torch T and other teaching data S _i are calculated in step S30.
Is set, and the creation of teaching data is completed.

When all the teaching data are created in this way, the reproduction mode (step S
Go to 3).

As described above, in this embodiment, since the laser torch T is automatically moved by the height sensor HS so that the laser torch T and the work W always keep a constant distance, the laser torch T and the work W collide as in the conventional case. There is no such problem, and the movement between teaching points can be performed easily and quickly. Moreover, since the postures of the laser torches T at the adjacent teaching points are usually similar to each other, there is an advantage that it is easy and labor-free for an operator to manually adjust them. Since there is no operation for returning the attitude of the laser torch T to the predetermined attitude every time, there is no danger of unnecessary rotation of the laser torch T.

E. Modifications One embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment, and the following modifications are possible.

The height sensor HS is not limited to the type that detects electrostatic capacitance, but may be a type that uses magnetism or light. For example, the arm 6 may be provided with an optical sensor head adjacent to the laser torch T to detect the relative position. As the optical sensor head used for such a purpose, for example, the one shown in Japanese Patent Application No. 60-153072 can be used. This optical sensor head
It can be used for keeping the distance to the work W at a constant value and controlling the attitude of the sensor in a constant direction. Therefore, if the present invention is carried out by using this optical sensor head as the relative position detecting means, not only the coordinate position (X, Y, Z) of the end effector but also its posture (θ, ψ)
Also the robot automatically adjusts and sets. Therefore, the posture adjustment by the operator is not necessary, and the robot RB can set the teaching points one after another based on only the NC data.

The present invention can be applied not only to PTP control robots that teach movements with multiple teaching points but also to CP control robots that teach movements with continuous work lines. At this time, the NC data becomes, for example, a continuous curve on the XY plane.

The X-axis and Y-axis are given in advance as coordinate data.
Not limited to NC data, it is generally a part of coordinate data of multiple degrees of freedom.For other degrees of freedom data, the sensor maintains a constant mutual positional relationship between the end effector and the workpiece. The present invention can be applied to any method of determining.

〔The invention's effect〕

As described above, according to the present invention, a part of the coordinate data prepared in advance is used, and the mutual positional relationship between the end effector and the work is automatically set by the sensor so that the end effector is set. Since it is operated, there is no danger of collision between the end effector and the work, and a large amount of teaching data can be efficiently created.

[Brief description of drawings]

FIG. 1 is a perspective view showing an outline of a mechanical structure of an industrial robot to which the invention is applied, FIG. 2 is a schematic block diagram showing an electric structure of the robot of FIG. 1, and FIG. 3 is a laser torch. 4 is a partial sectional view showing the detailed configuration of FIG. 4, FIG. 4 is a diagram showing the data configuration of teaching data, FIG. 5 is an explanatory diagram showing the operation of the embodiment, FIG. 6 is a flow chart showing the operation of the embodiment, FIG. 7 is an explanatory view showing the function of the height sensor, and FIG. 8 is an explanatory view showing a conventional teaching method. RB ... Laser cutting robot, 9 ... Control device, 10 ... Control panel, 11 ... External computer, T ... Laser torch, W ... Work, HS ... Height sensor

Claims (1)

[Claims] 1. Teaching of the robot using teaching point coordinate data for only a part of the degrees of freedom created in advance by a predetermined data creating means in teaching the operation of the end effector of the robot on the surface of a work. (A) The mutual positional relationship between the surface of the work and the end effector is detected by mutual position detection means included in the robot, and the surface of the work and the end are detected based on the detection result. While maintaining the mutual positional relationship with the effector in a predetermined relationship, the movement control means is used to move the end effector to a location indicated by the teaching point coordinate data, and (b) the end effector after or during the movement. After setting the posture of the effector to the desired posture, take in the position information and posture information of the end effector. (C) more than (a) and teaching method of the robot, characterized in that by repeating the process of (b) advancing the teaching.