JPH01283603A - Robot off-line teaching system - Google Patents

Abstract

PURPOSE:To simply input an attitude of a robot by approximating a work of a work object by a polyhedron, defining a local coordinate system on the specified surface and teaching a work point on a graphic display screen. CONSTITUTION:A work 1 which has been approximated by a polyhedron is brought to picture drawing on a graphic display screen of an off-line programming device, three apexes for constituting the surface F for allowing a robot to execute a work, that is, the surface F for designating a work point are designated and specified, and a local coordinate system L on this surface F is also defined by a prescribed method. Subsequently, when teaching is executed by designating the work point on the specified surface F, this teaching point P is converted to a world coordinate system W being a common coordinate system of the robot and the work by an inverse matrix of a transformation matrix in which a graphic display device has converted a three-dimensional image to a two-dimensional screen coordinate system S on the screen. Also, said point is converted from the world coordinate system W to a local coordinate system L, and an attitude of the robot is defined by the local coordinate system L on the designated surface. In such a way, the attitude of the robot can be inputted simply.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a robot offline teaching method for teaching the posture of a C robot using a graphic display device.

In the conventional offline teaching method for technological robots, teaching data to the robot is transmitted to a location separate from the robot introduction line.
In other words, the teaching program [1 gram] is created, but it is difficult to make the robot take any posture using a graphic display device without moving the robot itself.
This is quite difficult, and conventionally, in order to make the robot take a posture, the robot's posture data, that is, the coordinate values X, Y, Z of the tool tip point in the Cartesian coordinate system and the inclination (of the tool (tool coordinate system)) W, P, R) manually, or
Or, the value of each axis of the robot, for example, if the robot has 6 axes, the value of each of the 6 axes (θ, W.

U, Y, β, α) were entered manually. Therefore, in many cases, humans end up calculating the robot's posture by hand to create teaching data.

Problems to be Solved by the Invention There is a method of inputting the robot's posture (X, Y, Z, W, P, R>) based on the coordinate values of the tip point of the tool and the inclination of the tool.
Each axis of the robot (θ, W, U, Y.

The method of inputting .beta., .alpha.) places a heavy burden on the operator who creates the teaching data, and takes a long time/2 hours to create the teaching data.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an offline teaching method that allows the robot's posture to be easily input using a graphic display device.

In particular, it is an object of the present invention to provide an offline teaching method suitable for teaching robot work points such as spot welding.

Means for Solving the Problems In order to achieve the above object, the robot offline teaching method of the present invention approximates the workpiece to be operated by the robot as a polyhedron, and stores the data of the vertices and sides of each surface in advance in an offline programming device. The above-mentioned workpiece is memorized, and the work point is specified by displaying the workpiece on the graphic display screen.The surface is specified by specifying the three vertices constituting the part on the graphic display screen, and the specified point is specified. define a local coordinate system on the specified surface, teach the robot's working point on the specified surface on the graphic display screen, and convert the taught robot's working point from the screen coordinate system to the local coordinate system. By doing this, the robot's posture is taught.

Action Draw a workpiece approximated by a polyhedron on the graphic display screen of the offline programming device, and draw the three vertices constituting the surface on which the robot is to work, that is, the surface on which the work point is specified, on the graphic eye play screen. The local coordinate system of the part is also determined by a predetermined method.
I'm out.

Then, when a work point is designated and taught on the specified surface, the teaching point is determined by the inverse matrix of the transformation matrix by which the graphic display device transforms the three-dimensional image into the two-dimensional screen coordinate system on the screen. Convert to the world coordinate system, which is a common coordinate system for the robot and workpiece, and then convert from the world coordinate system to the above local coordinate system, and the robot's posture will be defined in the local coordinate system on the specified surface. .

Embodiment FIG. 2 is a block diagram of main parts of an offline programming device that implements an embodiment of the present invention, and 10 is a central processing unit (10) that executes processing of the offline programming device.
(hereinafter referred to as a CPU), the cPtJ10 has a ROM11. RAM 12 used for temporary data storage and data storage for arithmetic processing. 13. Floating-point calculation block length for calculating determinants for coordinate transformation to be described later. Input/output board 14° hard disk controller 15. A display memory 16 having a frame buffer and storing the screen position of an image is connected by a path 17. In addition, if necessary, expandable RAM18
．． An expansion ROM 19 is connected to the bus 17. The input/output board 14 includes a keyboard 20 having various command keys and numerical keys, and a mouse 2 for moving a cursor on a graphic display screen and teaching the position on the screen.
1 is connected, and is also connected to the robot control device via the interface terminal of R3-2320.

Further, the hard disk controller 15 stores in advance, by the off-line programming device, the shape arc of a workpiece such as a car body, which is the work target of the robot for which the robot's operation program is to be created, and also stores teaching data. A hard disk 22 is connected thereto.

The workpiece shape data stored in the hard disk 22 is a boundary representation (Bounda) that approximates the workpiece shape as a polyhedron.
ry-Representation) format, and the data of the vertices and edges constituting each surface and the normal vector of the surface are stored based on the world coordinate system, which is a common coordinate system of the robot and the workpiece.

On the other hand, the display memory 16 is connected to a CRT control device 22 of a graphic display device, and the CRT il control device 22 is connected to a CRT display device 23 that displays an image of the workpiece and coordinate position data of the taught point. ing.

In the above configuration, when the keyboard 20 is operated to enter the teaching mode, the CPU 10 reads workpiece shape data from the hard disk 22 via the hard disk controller 15, and converts three-dimensional data such as perspective projection transformation per or parallel projection transformation Pa1 into two-dimensional data. A conversion process is performed to convert the workpiece shape into two-dimensional data, and the data is stored in the display memory 16. CRT it, 11 tll
The device 22 reads the work image data from the display memory 16 and draws it on the CR1 display device 20.

First, the designation of a plane for teaching a work point, the definition of a local coordinate system, and the principle of teaching a work point in this embodiment will be explained.

For example, if the shape of the workpiece is a rectangular parallelepiped as shown in FIG. Draw on top,
For example, the surface for teaching the work point is set to the vertex V1. V2. V3
When you click with the mouse in this order, the three vertices V1.
The plane F that constitutes V2°■3 is specified. In this example, the first point that was surprised in order to identify the
is predetermined as the origin of the local coordinate system, and the side connecting the first start point V1 and the second start point V2 is the Y axis of the local coordinate system, and the normal vector of the identified surface is the Z axis. , the direction obtained by multiplying the X-axis by the Y-axis vector and the Z-axis vector, that is, the local coordinate system is defined by the right-handed system, and the above three vertices V1. V2. From V3, the local coordinate system L (XL, YL,
ZL ) is obtained.

(N: Normal vector of surface F) Origin: ■1 ・・・・・・(4
) In this example, in order to specify the surface F, the position of the vertex that is first surprised is expressed in the local coordinate system L (XL, Y
L, ZL ) (7) The origin was set as the origin, and the Y-axis direction was defined as the direction from the first startled vertex ■1 to the next startled vertex V2, but it does not necessarily have to be defined like this. For example, the second You can use the surprised vertex ■2 as the origin,
Also, the surprised vertex V1. V2. It is also possible to input again which of V3 should be the origin. In addition, the normal direction of the identified surface is defined as one axis of the local coordinate system, and the other axis is defined as the vector direction connecting the two vertices of the startled vertex, and the other axis is determined in this way. It is only necessary to determine the right-handed system for the two axes.

In this way, after determining the local coordinate system on the plane F and the part F where the work point is to be taught, the work point on the plane F is set using the mouse 21.
I'll surprise you and teach you. Screen coordinate system S of this teaching point P
If the position at (Xs, Ys) is Ps (x, y), then the teaching point Ps (x, y) in this two-dimensional screen coordinate system S is
y) into a three-dimensional world coordinate system that is a common coordinate system between the robot and the workpiece (the data of the vertices and sides of each surface of the workpiece approximated by a polyhedron are defined by this world coordinate system). In this case, the method adopted by this offline programming device to convert the three-dimensional data of the workpiece into two-dimensional data of the screen coordinate system S in order to display the workpiece two-dimensionally is perspective projection transformation Per, or , parallel projection transformation Pa1, etc., the teaching point Ps (x, y) in the surprised screen coordinate system is transformed into the world coordinate system W by the inverse matrix of the transformation matrix adopted by the offline programming device. is converted into a teaching point Pw (x, y, z). That is, it is converted by the following equation.

In the case of perspective projection transformation per, Pw (x, y, z) = Per-'Ps (x, y)...
...(5) In case of parallel projection transformation Pa1, Pw (x, y, 7) = PaJ-1Ps (x, y)...
...(6) Next, let M be the transformation matrix from the local coordinate system to the world coordinate system W. This transformation matrix M is expressed by the above (1) to (
4) The coordinate position of the teaching point P in the local coordinate system is derived from the following equation.

PL (x, y, z) = M”Pw (x, y, z)...
(7) In this way, the position of the tool tip point of the specified work point is determined by the coordinate position 11PL (X, V, Z) in the local coordinate system of the specified point F and the slope F.

Also, the inclination of the tool (W, r', R) is the same as the coordinate axes of the local coordinate system (W, P, R) = (0°0.0)
Then, the robot posture at teaching point P is PL(x, y, z
, O, O, O), and the posture data PL(x
, y, z, O, O, O) are displayed on the screen of the CRT display device 23.

In particular, when a robot works with two fingers of a tool such as spot welding, if the direction between the fingers is aligned with the y-axis, that is, the direction of the normal to the surface of the workpiece, the inclination of the tool can be adjusted. It is only necessary to teach the value of R, which represents the amount of rotation of the parameters (W, P, R) around the y-axis. For example, when working with a tool 30 having two fingers 31 and 32 as shown in FIG. 4 at a legal angle of 31° and 32, the direction of the approach vector between the fingers 31 and 32 may be set as the Z-axis direction. .

In FIG. 4, σ represents the orientation vector, 100 represents the normal vector, and T represents the position vector of the tool tip point.

Next, FIG. 3(a) shows the teaching process in this embodiment.
, (b) together with the processing flowchart.

As mentioned above, when the teaching mode is set, the CPU 10 reads the work data from the hard disk 22, converts it into two-dimensional data, stores the two-dimensional data in the display memory, and
A workpiece shape is drawn on the screen of the RT display 23. Then, the index i is set to "0" (Step S1), and it is determined whether there is a big input from the mouse 21 (Step S2). Operate the mouse 21 to move the cursor on the CRT screen and place the cursor on one vertex of the surface to be specified (for example, below VL in FIG. 1, this will be explained with reference to the example in FIG. 1). When the button of the mouse 21 is operated to start the vertex v1, the checked coordinate value, that is, the coordinate value of the vertex v1 in the screen coordinate system S (x,
y) in register Ri (=Ro) (step S
3). Next, it is determined whether the index i is "2" (step 34), and if it is not "2", the finger Fii is incremented (step S5), and the process returns to step S2 again to determine whether there is the next big input. If there is a big input, the coordinate value of the big point is stored in the register Ri. Thus, the three vertices ■1°V2. When V3 is surprised and the index i becomes "2", it is determined whether there is a surface that constitutes F according to the vertex coordinate system stored in registers RO, R1, and R2.
Judging from the data stored in the display memory 16 (step S6), if there is an erroneously surprised surface and there is no such surface, a message indicating that the surface cannot be identified is displayed on the CRT screen, and the registers RO to R2 are cleared. Step S7)
, returns to step S1 again and performs the process of specifying the surface.

In this way, when the surface F is specified, the origin is the first picked vertex 1, the unit vector from the vertex V1 to the second picked vertex V2 is the y-axis, and the normal to the specified surface F. The direction is 7@ and the direction determined by the right-handed system is the X axis, that is,
The local coordinate system is also determined by the processing shown in equations (1) to (4).

Then, the CPU 10 judges whether or not the point on the specified plane F has been surprised (step S8). When the operator has surprised the desired work point as the teaching point P, the CPU 10
The floating point processor 13 converts the big point ps (x, y) in the screen coordinate system to the position pw (x, y) in the world coordinate system W.

y, z), and the floating point arithmetic processor 13 first converts the big point PS in the screen coordinate system using the inverse matrix of the three-dimensional to two-dimensional transformation matrix adopted by this offline programming device. (X, V) is converted into a teaching point pw (x, y, z) of the world coordinate system. That is, if it is a perspective projection transformation per, then by performing the equation (5), and if it is a parallel projection transformation Pa1, it can be
By performing the operation Ω of equation 6), the teaching point ps (x, y), which is the big point, is transformed into the point PW (X, 'l/
.

Convert to 2). Then, the teaching point pW (x, y, z) in the world coordinate system is computed according to equation (7), and the teaching point pL (X) in the local coordinate system is calculated.

y, z) (step 89), the CPU 10 calculates the teaching point PL(X, V.

Z) is written in the display memory, and the data of the robot's posture at this teaching point is displayed on the CRT screen (step 510). In addition, at this time, the tool posture is represented (W,
P, R) are the same as the coordinate axes of the local coordinate system,
[1bot posture data is PL (x, y, z, O, O, O
) is displayed. Then, the message "Do you want to correct the posture data?" is displayed on the CRT screen (step 511).
), when the operator inputs rYEsJ from the keyboard 20 (step 512), the data of the designated plane F and the posture data PL (x, y, z, W, P, R) are stored in the hard disk 22 (step $15). .

Further, when rNOJ is input in step 812, the robot posture data PL (x, V, z, W ,P.

R) is corrected (step 313.14), and when a correction end command is input, the data of the attitude f and the specified plane are stored in the hard disk. This data is modified by changing the tool posture parameters w and p.

R (for spot welding, etc., as mentioned above, only R and W and P are left as "0"), or if a teaching point has already been taught on the same designated surface and that teaching point For example, if the teaching point moves parallel to the Y-axis of the local coordinate system, the value of the X-axis should be the same at all teaching points, but the start position may be shifted. If they are not the same, use this
Correct the value of .

Then, the CPU 10 displays a message on the CRT screen asking whether to continue teaching work points on the same designated surface (step 816). If the operator inputs rYEsJ (step 517), the process moves to step S8, Steps 88 to S16 are performed, and if "NO" is input, the work point teaching for one surface F is completed, and if the teaching mode is not switched, the processing starts again from step S1.

As described above, the posture of the robot is taught sequentially, and a teaching program can be easily created offline.

Although the mouse is used to teach the position on the CRT screen in this embodiment, other means of teaching the cursor position by moving the cursor may also be used; for example, a light pen may be used to teach the position on the CRT screen. You can do it like this.

Effects of the Invention When teaching the robot posture off-line, the present invention allows easy input of the robot posture, making it easy to create offline programming. In particular, in the present invention,
It is ideal for teaching robot work such as spot welding, where the working direction of the tool is perpendicular to the work surface.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram illustrating the principle of specifying a work plane, defining a local coordinate system, and teaching a work point according to the present invention, and Fig. 2 is an offline programming giM implementing an embodiment of the present invention.
3(a) and 3(b) are flowcharts of the robot posture teaching process in the same embodiment, and FIG. 4 is an explanatory diagram of a tool suitable for the deeding method of the present invention. 1... Work, F... Surface, Vl, V2. V3...
Vertex, L (XL, YL, ZL)... Local coordinate system, S (Xs, Ys)... Screen coordinate system, W
(XW, YW, ZW)...World coordinate system. Patent applicant Fanuc Co., Ltd. Agent Patent attorney Matsushi Takemoto (2 idiots) No. 10-1 Fig. 3 (0) Fig. 3 fbl

Claims (1)

[Claims] The workpiece to be operated by the robot is approximated by a polyhedron, data on the vertices and edges of each face is stored in advance in an offline programming device, the workpiece is displayed on both sides of the graphic display, and the face on which the work point is specified is displayed. A surface is specified by specifying the three vertices that make up the surface on the graphic display screen, a local coordinate system on the specified surface is defined, and the robot's work point on the specified surface is graphically displayed. A robot offline teaching method characterized in that the posture of the robot is taught by teaching on both sides of a display and converting the taught work point of the robot from the screen coordinate system to the local coordinate system.