JPH03220603A - Robot control method - Google Patents

Abstract

PURPOSE:To easily change the definition of a coordinate system by using a communication means to retrieve and refer to the coordinate system reference table of another robot controller at the time when the designated coordinate system definition is not executed in the working program of a local robot controller. CONSTITUTION:When a coordinate system designated as the reference of operation at the time of executing an operation instruction is not described in the working program of a local robot controller itself and cannot be referred because it is not registered in a reference table, a communication means 303 is used to refer to the converted coordinate system definition in a retrievable coordinate system reference table described in the working program of another robot controller 302, and thereby, coordinates of this operation instruction are transformed to robot coordinates to operate a robot. Consequently, the definition of a certain coordinate system is described only in the working program of one robot controller 301 or 302 on the robot system where plural robots 304 and 305 perform the work in cooperation with each other. Thus, the coordinate system definition is easily changed.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a robot control method that can arbitrarily define a coordinate system as a reference for robot operation on a robot workspace. This paper relates to a control method when multiple robots perform collaborative work.

[Conventional technology]

In general, a robot control device can define multiple coordinate systems in the operating space of the robot it controls, and it is possible to define which coordinate system the point data in the operation command in the work program is based on. You can choose. Generally, the types of coordinate systems are world coordinate system,
Defined as base coordinate system, tool coordinate system, and workpiece coordinate system.

The world coordinate system is a coordinate system defined in space when arranging robots, peripheral devices, and workpieces, and only one exists in a certain robot system.

The base coordinate system is a coordinate system whose origin is an arbitrary coordinate on the world coordinate system, and is usually a coordinate system aligned with the origin of the robot and with the robot as a reference.

The tool coordinate system is a coordinate system based on the plane in which the tool is attached at the tip of the robot. The position of this tool coordinate system moves as the robot moves.

The workpiece coordinate system is a coordinate system for the purpose of defining workpiece placement, pallets, etc., and is defined based on the world coordinate system, base coordinate system, or other workpiece coordinate system.

For example, in a system as shown in FIG. 7, when world coordinates, base coordinates, and workpiece coordinate systems are defined, the relationship among these coordinate systems will be expressed as shown in FIG. 8. That is, a base coordinate system 702 and a first work coordinate system 704 are defined on a world coordinate system 701,
Furthermore, a second workpiece coordinate system 70 is provided on the base coordinate system 702.
6 is defined. The coordinate system definition in FIG. 7 is performed by designation in a work program 901 as shown in FIG.

Defining a coordinate system is equivalent to defining a conversion rule for point data based on an arbitrary coordinate system on a base coordinate system based on the robot. 1st
Figure 0 shows an example of conversion. The robot control device 1007 is
The definition 1008 of the coordinate system of the robot to be controlled is read by the work program reading means 1006, and a coordinate system reference reference 1004 that can be referenced from the work program 1001 is created. In the robot movement command 1009 in the work program, the point data described as the number of bows in the movement command and the coordinate system specification are used to interpret which coordinate system the point data is based on, and to create the point data. 1002 and the coordinate system reference table 1004 are converted into coordinates on the base coordinate system of the robot by the calculation means 1005, each joint angle of the robot is determined, and a command is output to the robot control unit 1006.

Usually, one robot is connected to a robot control device, and work programs, point data, and coordinate system data are stored in the robot control device and are unique to the robot.

When multiple robots work on one work,
Conventionally, a system as shown in FIG. 11 has been used. In other words, for one workpiece W, four robots R
When performing work with a, Rb, Rc, and Rd, each robot R
a-Rd are controlled by robot controllers 1101a-d. The robot control devices 1101a-d have reading and interpreting means 1103a-d, execution means 1104a-d, and execution means 1104a-d for reading and interpreting work programs 1102a-d for each robot.
The robots 1105a to 1105d are connected to each other by communication lines 1106a to 1106c+ in order to coordinate the operations of the robots Ra to Rd.

The operator separately programs and stores each operation of each robot (Ra-Rd). At this time, the coordinate system related to the operation command of each robot is defined in each robot control device, and the definition is valid only for the robot that each robot control device is in charge of.

[Problem to be solved by the invention]

However, as shown in Figure 11, multiple robots
In order to perform work on one workpiece, the robots are arranged so that their operating ranges overlap, and within that range there is a workpiece coordinate system 1107 that is commonly referenced.
When operating based on the workpiece coordinate system 1107, the definition of the workpiece coordinate system 1107 is defined in each robot control device 1101.
Since the workpiece coordinate system 1107, which is commonly referred to, must be defined in each robot control device 1101a-d. That is, the robot control device 1101a of the robot Ra runs the program 1201 shown in FIG. 12(a), and the robot control device 1101b of the robot Rb runs the program 1201 shown in FIG.
It is defined as the program 1202 shown in b). The same applies to robots Rc and Rd. When changing the definition of this workpiece coordinate system, the definition of the workpiece coordinate system 1107 of the control device 1101a of the robot Ra and the workpiece coordinate system 11 of the control device 1101b of the robot Rb must be changed.
The problem was that the definition of 07 had to be changed.

[Purpose of the invention]

In view of the above problems, the present invention provides a robot control method that allows the definition of a coordinate system to be easily changed on a robot system in which a plurality of robots perform cooperative work.

[Means to solve the problem]

In the method according to the present invention, point data specified as an argument of a robot operation command is also specified in a robot control device equipped with a transmission line and communication means for exchanging coordinate system definition information with a plurality of robot devices. has means for converting the designated coordinate system into a robot operation coordinate system using the designated coordinate system as a reference, and if the designated coordinate system definition has not been performed in the work program of the self-robot control device, using the communication means, By searching and referencing the coordinate system reference tables of other robot control devices, a target conversion table is obtained and the robot is operated.

[Effect]

A robot control device capable of implementing the method according to the present invention includes:
If a certain coordinate system is defined in the work program of any one robot control device, there will be a consistent relationship between the coordinate systems of a robot system in which multiple robots perform cooperative work, and when changing the definition of the coordinate system, can complete the change in the definition of the coordinate system in the robot system only by changing the work program of the robot control device that is defining the coordinate system.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

Here, FIG. 1 shows an example of a robot control device that implements the control method according to the present invention, FIG. 3 shows an example of a robot system, and FIG. 5 shows an example of a work program in the robot system shown in FIG. Example, FIG. 4 is a coordinate system related diagram according to the second embodiment of the work program shown in FIG. 5, and FIG. 6 is an example of the coordinate system reference table in the coordinate system related diagram of FIG. The figure shows an example of the coordinate system reference procedure in the robot system of the example shown in FIG.

In FIG. 1, a robot control device 109 includes a microcomputer (hereinafter referred to as CPU) 101 and a
101 and a bus 108 connected to the ROM 102 for storing management programs, etc., and the RAM 104 for storing work programs, point data, coordinate system reference tables, etc.
, manual data input device with CRT display (hereinafter referred to as CRT)
/MDI) 105, an operation panel 106 having a work selection switch, etc., a communication means 106 for communicating with other SEBOT control devices connected by a transmission path, and a robot control unit 107 connected to the robot's servo circuit. have.

The robot system in FIG.
304 and a second robot 605 are arranged.

A first work coordinate system 608 is defined as a common work space for the first robot 604 and the second robot 605.

Further, on the base coordinate system 607 of the second robot, there is a second workpiece coordinate system 61 in which the second robot 605 performs work.
0 is defined. This second workpiece coordinate system 610 is defined based on the base coordinate system 607 of the second robot.

In FIG. 5, the work program 501 in (a) is the third
First robot 604 in the robot system shown in the figure.
0 work program, and the work program 50 of (b)
2 is the second robot 6050 work program. The coordinate system definition unit 506 of the work program 501
The base coordinate system 306 of the robot is the world coordinate system 6
09 as a reference, indicating that the first work coordinate system 608 is defined with the world coordinate system 609 as a reference. The coordinate system definition unit 505 of the work program 502 defines that the base coordinate system 607 of the second robot is
It shows that the world coordinate system 609 is defined as a reference, and the second workpiece coordinate system 610 is defined as the base coordinate system 607 of the second robot.

The robot operation instructions of the work program will be explained.

The robot operation command 504 of the work program 501 is a command to move the tool tip of the first robot 7) 304 to the coordinates referenced by the point data P1 with the first workpiece coordinate system 608 as a reference.

The robot operation command 506 of the work program 502 is a command to move the tool tip of the second robot 605 to the coordinates referenced by the point data P2 with the first workpiece coordinate system 608 as a reference.

The worker saves the work program and point data to C.
It is input from RT/MDI 105 and stored in RAM 104. When an operator issues a command to execute a work program from the operation panel 106, the CPU 101 reads out the work program from the beginning and interprets it.

First, the work program 501 will be explained.

The CPU 101 reads the work program 501 from the beginning, and when it interprets the coordinate system definition section 506, the coordinate system reference table 620 shown in FIG. 6(a) is stored in the RAM 10.
Create on 4th.

This coordinate system reference table 620 is based on the world coordinate system 30
Starting from the coordinate system reference table 601 of 9, link 60
4, it is connected to the coordinate system reference table 602 of the base coordinate system 607.

This link 604 is a link connected in series. Similarly, a link 605 to the coordinate system reference table 606 of the first work coordinate system 608 defined with the world coordinate system 309 as a reference is a link connected in parallel.

Next, when the CPU 101 reads out the robot operation command 504, the CPU 101 reads out the first workpiece coordinate system 60 specified as an argument.
8 in the coordinate system reference table 620. The search process will be explained using FIG. The CPU 101 first refers to the top of the coordinate system reference table 601 (step 1), checks whether the coordinate system definition is the target coordinate system (step 2), and if the coordinate system definition is the target coordinate system, the coordinate system is connected by a serial link. Check to see if there is a reference table that exists (step 3). In this embodiment, coordinate system reference tables 602 . See. If a reference table connected in series is dropped, it is checked whether there is a reference table connected in parallel (step 4). If you continue to refer sequentially and find the target coordinate system reference table 606,
-Create a conversion table based on the world coordinate system (
Step 9). Next, it is checked whether this conversion is a request from another robot control device (step 10). In this embodiment, since the request is not from another robot control device, the base coordinate system 306 is used as a reference. A conversion table is created (step 11). Using this coordinate conversion table, the point data specified as an argument in the robot movement command is converted into coordinates on the base coordinate system 606 of the first robot 6040 (step 12), and transferred to the robot control unit 107 (step 12). Step 13).

Next, the work program 502 will be explained.

The CPU 101 reads the work program 502 from the beginning, reads and interprets the coordinate system definition section, and similarly to the work program 501, the coordinate system reference table 660 shown in FIG. Create to.

Next, when the CPU 101 reads out the robot movement command,
The first number specified as the number of bows in the robot movement command.
A search for the workpiece coordinate system 308 in the own coordinate system reference table is started (steps 2 to 6). In the case of the work program 502, since it is not registered in its own coordinate system reference table, the communication means 106 is commanded to search the coordinate system reference table of another robot control device (step 7). The communication means 103 sends a search command to the transmission path 606 from the corresponding transmission path. Robot control part #6
02 waits for another robot control device to return the conversion table (step 8). In this embodiment, when the robot control device 302 sends a search command and the name of the coordinate system, the robot control device 301 receives these and searches its own coordinate system reference table (
Steps 1-6). When the coordinate system is discovered, the CPU 101 of the robot control device 301 uses the world coordinate system 3.
Step 10: Create a conversion table based on 09.
), and sends it to the robot control device 602 (step 14
). In the robot control device 302, the robot control device 6
Recreate the conversion table transferred from 01 to a conversion table based on the robot 20 base coordinate system 307 (step 11), and use this re-created conversion table to convert the point data P2 to the base coordinate system 307. In step 12), the robot controller 1
07 (step 13).

As mentioned above, even if the coordinate system definition is not performed in the work program within the own robot control device, if the desired coordinate system definition is performed in the work program of another robot control device, It can be referenced when executing robot operation commands.

〔Effect of the invention〕

According to the present invention, in a robot system in which a plurality of robots work cooperatively (15), the definition of a certain coordinate system is described only in the work program of one robot control device on the robot system. When changing the coordinate system definition, it is only necessary to make the change in the work program of the robot control device where the coordinate system definition is being performed.The coordinate system definition reference table is referenced when the robot movement command is executed, so it is easy for the operator to change the coordinate system definition. No burden.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of a robot control device for realizing an embodiment of the present invention, FIG. 2 is a flowchart showing an embodiment of the present invention, and FIG. 3 is a robot of an embodiment of the present invention. FIG. 4 is a diagram showing the coordinate system of the robot system in FIG. 3. FIG.
a) and (b) are the coordinates (1G) system reference table of one embodiment of the present invention, FIG. 7 is an explanatory diagram of an example of a robot system for explaining the conventional technology, and FIG. 8 is the coordinates in FIG. 7. System relation diagram, Fig. 9 is an example of a work program for explaining the conventional technique, Fig. 10 is a block diagram showing an example of a robot control device that realizes the coordinate system reference method of the conventional technique, and Fig. 11 is a diagram of the conventional technique. This is an example of a robot system. 109...Robot control device, 301...
...Robot control device that controls the first robot, 302...Robot control device that controls the second robot, 306... Information transmission path between robot control devices,
501... An example of a work program stored in a control device that controls a first robot. 2... An example of a work program stored in a control device that controls a second robot. An example is 0.630...Coordinate system reference table. (G) Figure 6(b)

Claims (1)

[Scope of Claims] Means for describing in a work program a definition of a coordinate system serving as a reference for the operation of a robot; means for converting the coordinate system definition in the work program into a coordinate system reference table and storing it; and a work program. means for referring to the coordinate system reference table and converting point data into robot coordinates of the robot's motion coordinate system when executing a robot motion command described in the robot motion command; and transmitting the point data to another robot control device having the means. In a robot control device that is equipped with a communication means that can communicate over If the coordinate system definition cannot be referenced, the communication means can be used to refer to the coordinate system definition that has been converted into a searchable coordinate system reference table written in the work program of another robot control device. A robot control method that operates a robot by converting the coordinates of a motion command into robot coordinates.