JP2628033B2 - Industrial robot controller - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an industrial robot, and more particularly, to a control device for a working robot that moves the robot to an accurate working position.

[Prior Art] FIGS. 9 to 14 show a control device in a conventional robot.
Description will be made based on the drawings. FIG. 9 is a configuration diagram showing a main part of a conventional robot control device. In the figure, (1)
Is a central processing unit (hereinafter, referred to as a CPU) composed of a microprocessor, etc., (2) is a read-only memory (hereinafter, referred to as a ROM) storing a robot system program, and (3) is a random access storing data, etc. Memory (hereinafter referred to as RAM), (4) is a communication interface, (5) is an input / output interface, (6) is a teaching box having various operation buttons for moving the robot by button operation, and (7) is a transmission. A D / A converter for converting the converted data from digital to analog, (8) a servo amplifier for moving to a predetermined position of the robot body (9) by an analog signal transmitted from the D / A converter (7), (9) ) Is the robot body.

FIG. 10 is an explanatory diagram showing the relationship between the CPU1, ROM2, and RAM3 in detail. A user program is stored in a specific area of the RAM (3) in the user program storage section (11), and the corresponding program is selected. Then, it is stored in the execution instruction storage unit (12) in the RAM (3). The user program fetched into the execution storage unit (12) is decoded by an execution instruction decoding unit (13), and then converted into an operation command signal by a position control unit (14) in the ROM (2). Signal is D / A converter (7)
The operation command signal is transmitted to the robot main body (9) via the servo amplifier (8) to perform a predetermined operation.

Here, the robot body (9) has a structure as shown in FIG. 11, and in the figure, (16) is an I-axis arm, and the x, y plane is centered on the I-axis (15). Moving. (1
8) is a II-axis arm, which moves on the x, y plane around the II-axis (17). (20) is a third axis arm,
It rotates around the shaft (19). Reference numeral (21) denotes a hand attached to the III-axis arm (20), which grips a work or the like (not shown).

FIG. 12 is a top view of the robot (9), where the position data is composed of x and y components, and the operation position command data is θ ₁ ,
It is assumed that it consists of _two components.

In general the current position of the robot (9), a point J ₂ x, become those manifested in y-coordinate, the length of the I-axis arm (16)
l ₁ , if the length of the _second axis arm (18) is l ₂ and θ ₁ , θ ₂ is determined, the current position (x, y) of the robot (9) becomes x = l ₁ cos θ ₁ + l ₂ cos (θ ₁ + θ ₂ ) [1] y = l ₁ sin θ ₁ + l ₂ sin (θ ₁ + θ ₂ ) [2] Note that θ ₁ , θ ₂
Is Is required.

FIG. 13 is a flowchart of a program stored in the ROM (2), and its operation will be described. That is, in step S _1, the position from the upper CPU data (x, y) is transmitted, in step S _2, movement command data is described above in its position data (x, y) from the position controller (14) [1] , [2], [3], [4]. In step S _3, the operation position command obtained as described above D / A converter (7) is transmitted to the robot (9) via a servo amplifier (8), the hand of the robot (9) (21) is moved to a desired position.

However, the arm of the robot (9) actually moves to a position outside a desired position. This is because it is difficult to accurately perform external origin input when performing origin search, or accurate measurement of arm length l ₁ and l ₂ data used to calculate θ ₁ and θ ₂ Is difficult, the values of θ ₁ and θ ₂ are also calculated at the same time with an error. In addition, the world coordinate system in which the robot (9) actually operates and the robot coordinate system are misaligned. It is said that this is caused by

Here, the world coordinate system is defined for the entire production system laid out in a factory or the like including a robot or the like.
This is an XY coordinate system, and is not generally set for individual devices or the like. On the other hand, the robot coordinate system is an XY coordinate system set for each robot according to the layout direction and position of each individual robot, and the conversion from the world coordinate system to each robot coordinate system is determined by the layout. Is done. That is, the world coordinate system is a coordinate system uniformly set for the entire production system, and the robot coordinate system is a coordinate system set centering on each robot for each robot. How the world coordinate system described above and the robot coordinate system are displaced will be described.
First, when trying to draw a straight line of X = 0, Y = 0 corresponding to the y-axis and the x-axis in the robot coordinate system on the world coordinate system, as shown in FIG. 14, both the Y-axis and the X-axis It is not a straight line. Therefore, there is a problem that the arm must be moved to an accurate position by manual operation using the teaching box (6) in order to correct the positional deviation.

[Problems to be Solved by the Invention] Since the conventional robot control device is configured as described above, the robot arm position is accurately moved to the work position by manual operation or the like due to the mechanical accuracy of the robot. In addition, it is necessary to teach the position, and this teaching operation takes a very long time. For this reason, there is a problem in terms of effective use of the robot control device.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems of the conventional apparatus. By using a correction plate having a simple structure, the position of the robot arm can be corrected in a short time and with high accuracy. It is an object of the present invention to obtain a robot controller capable of accurately moving an arm of the robot to a work position.

[Means for Solving the Problems] A robot control apparatus according to the present invention is a robot control apparatus for moving a robot arm having a plurality of axes to a desired position. A correction plate arranged in a (world coordinate system), the surface of which is divided into a number of small areas by vertical lines and horizontal lines, and having a plurality of intersections; means for storing position coordinates of intersections of the correction plates; Means for moving the arm of the robot to the intersection of the robot, storing the robot intersection position coordinates in the robot coordinate system corresponding to the intersection, and means for inputting the movement command value of the robot in the reference orthogonal coordinate system. The difference between the movement command value and the stored position coordinates of the intersection in the small area of the correction panel to which the movement command value belongs, and the ratio of the distance between the intersections, Means for obtaining correction coefficients in the x and y directions; means for converting the movement command value into robot target position data in a robot coordinate system based on the obtained correction coefficients and the stored robot intersection position coordinates. And characterized in that:

[Operation] In the robot control device of the present invention, while storing the position coordinates of each intersection of the correction board accurately arranged in the reference rectangular coordinate system (world coordinate system), the robot arm is moved to the intersection, and The intersection movement is stored as the robot intersection position coordinates in the robot coordinate system. When the movement command value of the robot is input in the reference rectangular coordinate system (world coordinate system), the small area of the correction panel to which the movement command value belongs can be known. From the difference value between the position coordinates of the intersection and the ratio of the distance between the intersections, the correction coefficients in the x and y directions are obtained, respectively.
Further, based on the correction coefficient and the robot intersection position coordinates, the movement command value is converted into robot target position data in the robot coordinate system.

Hereinafter, embodiments according to the present invention will be described in detail with reference to the accompanying drawings. In the figure, the same reference numerals as those in the conventional example indicate the same or corresponding parts. FIG. 1 is a configuration diagram of a main part showing a robot control device according to the present invention. In the figure, (1) is a CPU constituted by a microprocessor or the like, (2) is a ROM storing a program, (3) is a RAM storing data and the like, and (4) is a communication interface I.
/ F, (5) is an input / output interface, (7) is a D / A converter that converts a data signal from digital to analog, and (8) is an analog signal transmitted from the D / A converter (7). A servo amplifier that moves the robot body (9), (30) is a teaching box having a recording key and a NO designation key of integers 1 to n, and (31) is a CRT for directly inputting coordinate data.

FIG. 2 is a top view of a correction plate arranged in a movable area of a robot arm in a reference rectangular coordinate system (world coordinate system) and a robot body (9). Ruled lines are provided vertically and horizontally at intervals.

FIG. 3 is an explanatory diagram showing the relationship between the CPU (1), ROM (2), and ROM (3) in detail, and the user program is RAM (3)
Are stored in the user program storage unit (11), which is a specific area of the user program, and when the currently executing user program ends, it is stored in the execution instruction storage unit (12) in the RAM (3). The user program extracted to the execution instruction storage unit (12) is decoded by the execution instruction decoding unit (13),
It is converted into an operation command by the position control unit (14) in the ROM (2). At that time, in the present invention, the position control unit (14)
U (1) or directly keyed-in data is corrected to the robot coordinate system using the correction coefficients α and β obtained in the world coordinate system of the correction board (32), and the target position data, which is the working position of the robot, is corrected. Then, operation position command data is calculated. The operation position command data is for operating the robot body (9) via the D / A converter (7) and the servo amplifier (8).

4 and 5 are flowcharts of programs stored on the ROM (2), and the operation will be described. First, FIG. 4 is a flowchart showing the creation of a correction data table on the RAM (3).
Because i = 1 in S ₁₀ is when setting the movement position of the robot to the first intersection of the reference grid correction plate (32) in the initial condition. Step S ₁₁ (N is the standard squares number of intersections) and determines whether the data table creation work on RAM (3) is completed. If an END If completed, the correction plate in step S ₁₂ if not yet finished (32)
The robot is manually and accurately moved to the i-th intersection of the reference cell. As shown in FIG. 6 with respect to the reference grid intersections, since 1~n number (address) is attached, as in step S _13, after the robot movement, record button and 1~n By pressing the NO designation key, the RAM
(3) The vertical table NO and the horizontal line NO of the reference cell of the correction board (32) corresponding to the current robot position are stored in the upper table. At the same time, the x coordinate and the y coordinate in the robot coordinate system at that time are stored.

The increment Sarukoto step S ₁₄ in i, then set to NO at the intersection of the reference grid for moving the robot correction board (32). Step S ₁₀ as described above
Repeatedly performed by the operation of to S ₁₄ until 1~n th intersection, turn RAM a position table squares NO and the robot
(3) Create above. As described above, the preparation work of creating the correction data table is completed.

FIG. 5 is an explanatory diagram of operation after the coordinate data is input, from the step S _20, in the upper CPU (1), or directly keyed data reference orthogonal coordinate system (world coordinate system) The coordinate values (x _c , y _c ) are transmitted to the position control unit (14). Coordinate value in step _{S 21 (x c, y c} )
Of the vertical line NO and the horizontal line NO of the reference cell (coordinate system) of the correction panel are calculated. In other words, since the correction panel is drawn with vertical and horizontal lines in the x direction at Δx and the y direction at Δy at intervals determined as shown in FIG. 6, if the horizontal line NO is i and the vertical line NO is j, (However, fractions are truncated) and the coordinate values (x _c ,
y _c ) is between i to i + 1 of the horizontal line NO and j to j + 1 of the vertical line NO
It turns out that it enters between.

Now, the correction board coordinates corresponding to the horizontal line NO (i) and the vertical line NO (j) in the correction table are represented by (X _ij , Y _ij ) and the horizontal line NO (i +
1) The coordinates corresponding to the vertical line NO (j) are (X _i1j , Y _i1j ), and the coordinates corresponding to the horizontal line NO (i) and the vertical line NO (j + 1) are (X _ij1 , Y _ij1 ). It can be drawn as shown in FIG.
Therefore the results of step S _21, further coordinates (x _c, y _c)
Can be written as shown in FIG. 8 (a). Further, as shown in FIG. 8 at step S ₂₂ (a), the coordinates X _ij
And as the distance between X _i1J, the ratio of the distance between the coordinate X _ij and x _c alpha, the ratio of the distance between the distance and the coordinate Y _ij and y _c between the coordinate Y _ij and Y _ij1 β, α, β Find the value of

The distance between X _ij and X _i1j is Δx, and the distance between Y _ji and Y _ij1 is Δ
y Is required.

Step S ₂₃ is obtained in step S ₂₂ (i, j)
Then, a position in the robot coordinate system corresponding to (i, j) (this position is referred to as a robot intersection position coordinate) is obtained from the data on the RAM (3). Now, the x coordinate and the y coordinate of the robot coordinate system in the correction table are determined as follows. Horizontal line NO
(I), the coordinates corresponding to the vertical line NO (j) are (x _ij , y _ij ),
The coordinates corresponding to the horizontal line NO (i + 1) and the vertical line NO (j) are (x
_i1j , _yi1j ), the coordinates corresponding to the horizontal line NO (i), and the vertical line NO (j + 1) are ( _xij1 , _yij1 ). Step S ₂₄ determines the input data (x _c, y _c) is the relative position of the robot coordinate system corresponding to the (x _R, y _R).

Wherein the distance between the coordinates x _i1J and x _ij, the ratio of the distance between the x _R and x _ij is to remarkably close to the α value obtained in step S _22, also between the coordinate y _ij and y _ij1 the distance, the ratio of the distance between the y _R and y _ij, by considered significantly close to the β value was calculated et at step S _22, as the relative position or target position data, (x _R, y _R ) Is required. FIG. 8 (b) shows this.

Hereinafter, a correction calculation for obtaining the target position data will be described.

Since the robot coordinate system is not a rectangular coordinate system, α, β
Is considered as a vector coefficient, and (x _R ,
y _R ).

therefore And from the equations (a), (b) and (c) Will be required.

Step S ₂₅ the target position data obtained by performing correction calculation by the position control unit, as described above (14) (x _R, y _R) from further operating position as in the conventional device by the position control unit (14) The movement amount of each component is calculated as command data, and the result is transmitted to the D / A converter (7), and the arm of the robot body (9) is moved to a desired position via the servo amplifier (8). Move to position.

[Effects of the Invention] As described in detail above, according to the robot control device of the present invention, all intersections created by vertical and horizontal ruled lines on the surface of the correction board are stored in advance as robot intersection position coordinates by teaching. Teaching work is extremely simple and takes no time. In addition, for the robot movement command value, the difference between the movement command value and the position coordinates of the intersection of the correction board, the distance between intersections, X,
Since the movement command value is converted into robot target position data by using the correction coefficient by obtaining the correction coefficient in the y direction, the position deviation of the robot arm can be corrected in a short time and with high accuracy. Therefore, there is an effect that control with high positioning accuracy can be realized.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a structural view of a main part showing a robot control device according to the present invention, FIG. 2 is a top view of a robot according to the present invention, FIG.
FIG. 4 is an explanatory diagram showing the relationship between a CPU, a ROM, and a RAM according to the present invention. FIGS. 4 and 5 are flowcharts of programs stored on a ROM according to the present invention. FIGS. Explanatory diagram showing the correction amount of the robot arm,
8 (a) and 8 (b) are explanatory diagrams of the operation of the robot arm according to the present invention, FIG. 9 is a configuration diagram of a main part showing a conventional robot controller, and FIG. 10 is a diagram of a conventional CPU, ROM and RAM. FIG. 11 is a perspective view showing the structure of a conventional robot body, FIG. 12 is a top view of FIG. 4, and FIG. 13 is a conventional RO.
Flowchart of the program stored on M, 1st
FIG. 4 is an explanatory diagram showing the relationship between the world coordinate system and the robot coordinate system for explaining the operation of the conventional robot. In the drawings, (1) ... CPU, (2) ... ROM, (3) ... RAM,
(4) Communication I / F, (5) Input / output interface, (7) D / A converter, (8) Servo amplifier, (9) Robot body, (30) … Teaching box, (31)… CRT, (32)… Correction board. The same reference numerals in the drawings indicate the same or corresponding parts.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-205713 (JP, A) JP-A-59-103109 (JP, A) JP-A-52-63578 (JP, A) JP-A-49-49 68183 (JP, A)

Claims (1)

(57) [Claims] 1. A robot controller for moving an arm of a robot having a plurality of axes to a desired position, wherein the controller is arranged in a movable area of the robot in a reference rectangular coordinate system,
A correction plate having a plurality of intersections whose surface is divided into a number of small areas by vertical and horizontal lines; a unit for storing position coordinates of intersections of the correction plates; and moving the robot arm to the intersections of the correction plates. Let
Means for storing a robot intersection position coordinate in a robot coordinate system corresponding to the intersection, means for inputting a movement command value of the robot in the reference orthogonal coordinate system, and wherein the input movement command value and the movement command value are Means for determining correction coefficients in the x and y directions from the ratio of the difference between the stored intersection coordinates in the small area of the correction panel and the distance between the intersections, respectively; Means for converting the movement command value into robot target position data in a robot coordinate system based on the stored robot intersection position coordinates, and a control device for an industrial robot.