JPH04347703A - Controller for multiaxial robot - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

[Industrial technical field] The present invention describes and manages the link structure of a robot using a programming language.
By analyzing the verbalized structure of the robot, a coordinate transformation module is created and transferred to the memory in the robot's numerical control device, making it possible to freely change the link structure and improve the robot's performance. This invention relates to a new numerical control device for a multi-axis robot that can flexibly respond to control.

0002

[Background Art] Due to recent technological innovations in the field of industrial robots, industrial robots have become smaller and more versatile.
It is increasingly being used as a unit of processing element in so-called FMS (high-mix, low-volume production system).

[0003] In FMS, the same processing station performs completely different tasks depending on the product type, so the processing tools attached to the tip of the robot arm also vary depending on the product type, and the processing steps of the robot are different. The program that describes this (hereinafter referred to as the "robot program") also differs depending on the product type. Therefore, when changing the product type, the robot program can be changed each time.

0004

[Problem to be solved by the invention] However, the creation of robot programs often depends on the type of processing tool.
For this reason, each time a new product type is added, the program must be changed significantly, and programming must be done near each robot.

[0005] Therefore, there is a problem in that a considerable amount of time must be spent on programming, and the robot must be stopped during this time.

[0006] Furthermore, as the number of production types increases, the number of robot programs increases, but even if the production type is the same, if there is a change in the machining tool, the coordinates of the point of action will change. This requires changes to the robot program, which must be registered in the numerical control device of each robot, which is not necessarily an efficient process.

[0007] Therefore, there are examples of attempts to unify robot programs by using library subroutines for machining tools, but in the end, the method of combining library subroutines using a linker without changing the main program is adopted. This does not reduce the number of robot programs to be managed.

[0008]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the multi-axis robot control device of the present invention first creates a program that describes the link configuration of the multi-axis robot using a programming section, and then Based on parameters that indicate the relative positional relationship between coordinate systems set for each joint of the robot, information indicating the displacement and posture of each joint of the robot and the position of the robot's hand are fixed to a specific joint axis of the robot. A conversion program is generated to mutually perform coordinate conversion with the information expressed in the reference coordinate system, and this is converted into command words that can be operated by the numerical control unit of the robot.

Then, the conversion program generated by the programming section is delivered to the numerical control section, and according to the conversion program, information on the hand position obtained from the state of each joint of the robot or each joint obtained from the position of the robot's hand is generated. The positioning of the robot is controlled based on information indicating the state of the robot.

0010

[Operation] According to the present invention, the link structure of the robot is described by a program, and a coordinate transformation program regarding the position and orientation of the robot is generated based on the program and transferred to the numerical control section of the robot. Since it is possible to flexibly deal with changes in the structure, even if the link structure of the robot is rearranged or the machining tools are changed, there is no need to make any changes to the program that describes the robot's motion, and the robot's motion will be improved. The number of such programs can be reduced, and the effort required for their management and maintenance can be reduced.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The control device for a multi-axis robot according to the present invention will be explained below according to the illustrated embodiments.

FIG. 1 shows an example of the hardware configuration of a system according to the present invention.

[0013] A robot used in an FMS environment has a connecting member so as to increase the degree of freedom of movement, and is composed of a combination of at least one or more arm parts, and
It is based on a "modular robot unit" that has a working end. This "modular robot unit"
This is also called a modular assembly type robot, and is a robot configured so that the link structure of the robot can be freely modified by the user. However, from the viewpoint of guaranteeing the solution to the inverse kinematics problem described later, this is currently limited to predetermined combinations.

The robot 1 is designed to perform operations according to a robot program based on instructions such as position sent from the servo unit 3 of the numerical control device 2. Here, servo control is applied to each degree of freedom of the robot 1, and can also respond to speed instructions in order to perform a return-to-origin operation.

[0015] Inside the numerical control device 2, a LAN I/F (
Except for cases such as DMA (direct memory access) performed in interface) 4, etc.,
is in charge of the process. Basically, the CPU 5 can be a general-purpose CPU such as Intel 80960 or Motorola 68030, and operates based on a control procedure recorded in advance in the control program storage section 6.

The LAN I/F 4 is a part that connects the LAN trunk line 7, which is a high-speed data bus, and the numerical control device 2, and performs processing such as packet transfer control. The program and the program that describes the link structure of the robot 1 (hereinafter referred to as the "module configuration program") are connected to the LAN backbone 7.
It is transferred via.

Reference numeral 8 denotes a robot program storage section, in which robot programs are recorded in two ways.

The first recording mode is a recording mode in a language in which the CPU 5 can operate, that is, machine language. In this case, when the operation of the robot 1 is started, the recorded contents are interpreted as they are by the CPU 5 and then executed, and the operation of the robot 1 is realized through the servo unit 3. This method is called the so-called compiler method, and has the advantage of being able to quickly execute robot programs that include complex numerical calculations. It takes.

The second recording mode does not allow the CPU 5 to operate directly, but is a recording mode that follows a predetermined grammar. In this case, the control program storage unit 6 has a sequential interpretation procedure described in machine language in accordance with the grammar so as to realize robot motion based on the recorded contents, and based on the procedure, the CPU 5 reads the robot program storage unit 8 from the robot program storage unit 8. Read and execute the robot's operating procedures.

[0020] This method is also called the so-called interpreter method, and since it is a method in which interpretation is performed sequentially using a program, the disadvantage is that the execution speed is generally slow (however, the execution speed is generally slow (however, the execution speed is slow when the robot itself is operated). (This drawback is not very noticeable from the viewpoint of robot program execution because it takes time.) However, it has the advantage that it is easy to handle because it does not require compiling into machine language.

[0021] In this embodiment, any recording mode can be used.

[0022] The control program storage section 6 normally uses a read-only memory device (ROM) whose contents do not disappear even when power is not supplied. The control program storage unit 6 stores a so-called system program, which includes procedures for initializing the CPU 5, LAN/I/F 4, etc., sequential interpretation procedures in an interpreter method, and execution procedures according to the interpretation results. remembered. Such a procedure is written in machine language that the CPU 5 can understand, and has the characteristic that it is directly called by the CPU 5 and then executed.

Reference numeral 9 denotes a coordinate conversion unit, which converts the robot axis coordinate system (a coordinate system that describes the state of each arm by specifying the relative positional relationship between each joint with parameters) and the robot based on the robot program. It stores the conversion process of machine language for processing coordinate conversion between the Cartesian coordinate system fixed to the base axis and the like. This conversion process has the property of being called sequentially as necessary in realizing robot motion.

Here, it is assumed that the coordinate transformation unit 9 satisfies the following requirements.

(1) From the perspective of the CPU 5, the conversion process must always be written starting from a predetermined address.

(2) If there are multiple conversion processes,
Each process must be described starting from a predetermined address when viewed from the CPU 5.

(3) Each conversion process performs conversion as specified in relation to one or more arguments and one or more return numbers, and may have Markov property. That is, it is also allowed to generate a return number based on information from a previous call in the same process.

Reference numeral 10 denotes a tool subroutine unit, which stores machine language processes for controlling a machining tool attached to the working end of the robot 1 or at an arbitrary position.

This tool subroutine unit 10 also satisfies the requirements (1) to (3) above.

The basic difference between the coordinate transformation unit 9 and the tool subroutine unit 10 is that the coordinate transformation unit 9 is an essential unit used to realize the operating procedure of the robot program. The tool subroutine unit 10 is not called unless an explicit procedure for using a tool is described in the robot program.

The configurations of the coordinate transformation unit 9 and the tool subroutine unit 10 are conceptually shown in FIGS. 3 and 4.

The coordinate transformation unit 9 takes the form of a package of a series of subroutines starting from a specific address on the CPU 5.

Specifically, the format is as shown in FIG. That is, the program of the coordinate transformation module is arranged following the branch address to the entry of each coordinate transformation module. Regarding coordinate conversion, a conversion module for position and displacement between axial coordinates and Cartesian coordinates is provided.

With this format, even if the coordinate transformation process changes due to a change in specifications, the entry point will not change, and the contents stored in the control program storage unit 6 and robot program storage unit 8 will not be directly changed. You can avoid it.

The tool subroutine unit 10 is a CPU
It takes the form of a package of subroutines starting from a specific address on 5, and has a format as shown in FIG. This is based on the same idea as in the case of the coordinate transformation unit 9.

The coordinate conversion unit 9 uniquely performs the conversion for one entry, but the tool subroutine unit 10 differs in that all processing is performed using only one entry. The reason for this is that the number of subroutines that should be prepared in advance cannot be specified because the parameters that must be handled generally differ depending on the shape of the tool.

Regarding the passing of arguments in the coordinate transformation unit 9 and the tool subroutine unit 10, a method is adopted in which the arguments are piled up on a stack and passed to the subroutine, as is done when realizing a function in a general program. . This is because there can be virtually no restrictions on the number of arguments.

Next, how the numerical control device 2 having the above configuration operates will be explained. For convenience of explanation, it is assumed that the robot program shown below is recorded in the robot program storage section 6. The format may be either a compiler method or an interpreter method.

Line number Statement 10
Point1=(10,20,30)20
Point2 = (50, 60, 70) 30 O
N=1 40 OFF=0 50 MOVE Point160 T
OOLS 1, ON 70 MOVE Point280 T
OOLS 1, OFF

[0040] Here, "P
ointX=( , , )” is a command to define coordinate values in the Cartesian coordinate system, “=” of “PointX=”
"~ = ~" statements other than "~ = ~" are numerical assignment statements, "MO
VE" command is a command to move the working end of the robot to a specified position, "TOOLS n, ON (or OFF)"
1 and 2 respectively indicate commands for controlling ON/OFF of the n-th chuck.

First, in the setting process from line numbers 10 to 40, the coordinate values of Point 1 (10, 20, 30)
and the coordinate values (50, 60, 70) of Point 2 are stored in a specific position in a memory (not shown). Then, integer values of 1 and 0 are assigned to the numerical variables ON and OFF, respectively, and are stored in specific locations in the memory (not shown).

[0042] In line number 50, "MOVE Point
1'' command moves the working end of the robot 1 to the Point 1 position.

By the way, since the coordinate values of Point 1 are coordinate values in the Cartesian coordinate system, in order to convert them into values in the axis coordinate system of robot 1, the position and orientation of each axis must be calculated. .

Therefore, first, the "Cartesian coordinates → axis coordinates" conversion process on the coordinate conversion unit 9 is called with the coordinate value of Point 1 as an argument, and a command is sent to the servo unit 3 based on the axis coordinate value obtained after conversion. robot 1
The process is to run the .

[0045] Line number 60 “TOOLS 1, ON”
The command performs ON control for tool number 1. For example, if the operation content of tool number 1 is related to gripping control of a workpiece, the instruction is to operate the tool with the corresponding number to grip the workpiece. In executing the command, it is embodied in the form of a call to the tool subroutine unit 10,
The subroutine is called with the arguments at that time being "1, 1".

Next, the moving operation to Point 2 at line number 70 is realized by processing using the coordinate transformation unit 9 in the same manner as described for line number 50.

[0047] Then, line number 80 "TOOLS 1
, OFF" command, OFF control is performed for tool number 1. In the case of workpiece gripping control, this is a command to release the workpiece gripped by the tool, and is a countermeasure to the action content of line number 60. The instruction is executed in the form of a call to the tool subroutine unit 10, similar to the "TOOLS 1, ON" instruction, but its arguments are "1, 0".

The robot program as described above is created by the programming unit 11 (see FIG. 1).

That is, the robot program created by the editing section 12 is sent to the compiling section 13, where it is converted into machine language while referring to the CAD data 14, and then is sent via the LAN I/F (interface) 15. TeL
It is placed on the AN trunk line 7 and sent to the numerical control device 2.

Next, we will move on to a description of the "module configuration programming unit."

This "module configuration programming unit" generates a conversion program for mutually converting relative position information in each degree of freedom of the robot and absolute position information of the working end from the module configuration program. This is then converted into command words that can be operated by the numerical control device 2.

As mentioned above, the module configuration program is a program that describes the link structure of the robot 1. Specifically, it describes the information shown below for each arm, and it is written in the form of a high-level language. This is a written information file.

a. Arm length b. Connection method between the arm and the arm (or base portion) that serves as a reference for its position c. When the connection is made by a shaft with rotation, the relationship between the rotation angle and the rotation pulse d. Relationship between relative movement distance and pulse when the connection is made by an axis that moves in a straight line

0054
For example, assume a two-arm horizontal articulated robot 16 as shown in FIG.

That is, the robot 16 has a first arm 18 rotatably supported on its base shaft 17, and a second arm 19 rotatably supported at the end of the first arm 18. installed. At the tip of the second arm, there is a tool mounting shaft 2 that can be slid vertically.
0 is attached, and a tool 21 is attached to its lower end.
, 21' is assumed to be provided with a rotation mechanism 22 for selectively using them.

An example of a list of module configuration programs in this case is shown below.

List example) ROBOT RobotName (p1, p2, p3
)=ARM1+ARM2+ARM3

−(i
) Construction of ARM1
(p1); -(ii) l
length=350mm shifted 10m
m; -(iii) Joint to
BASE with 0 degrees,
0 degrees;
-(iv),(v)
Freedom=1000 pulses/1
degree - (vi) Limit
of Freedom (p1) = 0 degree
to 270 degrees
-(vi
i) End of ARM1; Construction of ARM2 (
p2); length=250mm
fted 15mm; Joint to
ARM1 with 0 degrees, 0
degrees Freedom=1000 pulses/
1 degree; Limit of
Freedom=0 pulse to 270
000 pulses End of ARM2; Construction of ARM3 (
p3); Extend to ARM2
with 0 degrees, 0 degrees
Grees;
-(v)
length=100mm+Freedom(p3
) shifted 70mm; Freedom =1000 pulse
s/1mm; Limit of Free
dom=0mm to 100mm End
of ARM3 End.

[0058] Here, the meaning of each word regarding the programming languages listed above will be explained.

(i) "RobotName" is the name of the robot 16. Then, “ARM1”, “ARM2”
", "ARM3" is the name of the arm that makes up the robot 16, "ARM1" is the name of the first arm 18, "ARM
2" is the name of the second arm 19, and "ARM3" is the name of the tool mounting shaft 20.

[0060] Moreover, the parameters p1, p2, p3 are as follows:
This is a parameter that gives meaning that the axis coordinate system is constructed in this order. In addition, here p1, p2,...
This is simply the first parameter,
Since the names have the meaning of ordering, such as the second parameter, etc., it is of course possible to use other names such as axis1, axis2, etc.

The description of the configuration of the robot 16 is as follows:
This is done between the declaration sentence starting with ``ROBOT'' and the declaration end sentence ``End.''.

(ii) The description of each arm is “Const
ruction of xxxx” to “End
It is determined by the contents written up to "of xxxx".

(iii) "length=..." is the distance between the joints of the arm, that is, between the rotary joint and the rotary joint, or between the rotary joint and the translational joint, unless otherwise specified. It represents the distance between two translational joints, or between one translational joint and another translational joint.

In the above example, the length between the joints of the first arm 18 is 350 mm, and the displacement of the first arm 18 in the rotation axis direction with respect to the base shaft portion 17 is 10 mm, which is described by "shifted". are doing.

[0065] Note that one arm may have two or more arms. In this case, in order to clearly indicate which parameter is the distance between them, "length (p1) = ~
It takes the form ``~~shifted~~~~''.

[0066] Furthermore, if the joint of the arm has a structure of a translational joint rather than a rotational joint, "length=
The definition sentence "..." describes the relationship of degrees of freedom with respect to the arm. In the above “ARM3” configuration, “Free”
dom(p3)" expands the degree of freedom in the sliding direction. This is because the tool 2 is attached to the tool mounting shaft 20
1, 21' means an extension of the stroke.

(iv) "BASE" is a reserved word and means the base portion 17. The absolute (Cartesian) coordinate system set on this base portion 17 is the reference coordinate system.

(v) In the description of the connection relationship, “Joint
to～with～” or “Extend t
"o~with~" is used.

Here, the sentence "Joint to" means that an arm is connected to another arm by a rotational joint, and the sentence "Extended to" means that an arm is connected to another arm by a translational motion. It means there is.

Furthermore, the part following "with" is written to determine what angle the arm is connected to with respect to the axis to which the arm is attached. Since the notation is performed using polar coordinates in the horizontal plane, it is expressed in two dimensions. Note that, regarding the reference direction vector here, a vector in the same direction as the attachment axis of the arm is used as a reference.

It is known that the link structure of a robot can be expressed by four link parameters (De
navit-Hartenberg notation), so the above-mentioned "length" command and "Joint" or "
The value described by the "Extend" instruction (e.g. "
ARM1", 350 (mm), 10 (mm), 0 (
The values of these four parameters can be calculated from 0(degrees) and 0(degrees)).

[0072] Therefore, the structure of one arm can be described using such an instruction. (For details, please refer to the "Computer Controlled Mechanical System Series"
See page 29 of "Basics of Robot Control" (Corona Publishing). ).

(vi) Connection conversion between electrical system and mechanical system is as follows:
Freedom = ~". Here, "Free
dom" is an instruction for defining the conversion ratio between electrical quantity and mechanical quantity for the parameter specified in the declaration of "Construction of~(parameter)".

In the above list example, “ARM1” and “A
“1000 pulse/1deg” related to “RM2”
ree” and “1000” related to “ARM3”.
"pulse/1 mm", which defines how many pulses are required to move the arm 1 degree or 1 mm.

(vii) “Limit of Fr.
The "eedom" statement is written to limit the range of movement in terms of degrees of freedom.

[0076] The movable range is expressed in units of mechanical quantity (mm, cm
, m, etc.) or a unit of electrical quantity (pulses, etc.).

Next, a module configuration program (hereinafter referred to as "tool configuration program") that describes the configuration of the tools 21, 21' provided on the tool mounting shaft 20 will be explained.

List example) TOOL (1; int p1, p2, p3) = TOO
L1/TOOL2 Construction of
TOOL1length=350mm; Extend with 0 degrees,
0 degrees; End of TOOL1
; Construction of TOOL2le
ngth=350mm; Extend with 0 degrees,
0 degrees; End of TOOL1
; Select of p1=1:TOOL1; p1=2:TOOL2; End of Select; Control of TOOL1PRIM t
ool1 (p2, p3) End of TOOL1 Control of TOOL2PRIM t
ool2 (p2) End of TOOL2 End.

In the above list, two tools 21 and 21' attached to the tool mounting shaft 20 of the robot are declared by "TOOL (parameter)=".

For example, "TOOL1" indicates tool 21, "TOOL2" indicates tool 21', and "/
' means that the two are in an equal relationship.

Among the integer-type parameters p1, p2, and p3 shown in parentheses of "TOOL( )=", parameter p1 is for selecting the tool, and the remaining parameters are passed as arguments to the external function. It is something that can be done.

The configuration of the tools 21 and 21' is "Cons
truction ofxxxx” to “End”
of xxxx”, and is determined by the contents written up to
The "with" command is as described above.

[0083] From “Select of ~” to “End”
The content written under "of Select" means that the tool selection process is performed according to the value of the parameter p1.

Furthermore, actual control of the tool is entrusted to an external function because it depends on the type of numerical control device and the CPU 5 used therein. "Control
The "PRIM" instruction between the "of~" and "End of~" statements is used by the external function "tool1" or "too
12''.

Next, the compilation of the module configuration program and tool configuration program as described above will be explained.

After the module configuration program (including the tool configuration program) is created by the module configuration programming unit 23 (see FIG. 1), it is converted into machine language, and finally it is converted into a series of machine languages as shown in FIGS. 3 and 4. The coordinate conversion unit 9 and the tool subroutine unit 10 are converted into a subroutine package.

That is, the module configuration program and tool configuration program created by the editing section 24 in the module configuration programming unit 23 are processed by the compiling section 2.
5, the code is converted into machine language, and then sent to the generation unit 26 of the conversion process.

A coordinate transformation unit 9 and a tool subroutine unit 10 are created as a collection of transformation processes created by the generation unit 26, and these are connected to the LAN trunk line 7 via a LAN I/F (interface) 27. and is sent to the numerical control device 2.

The handling up to the grammar analysis procedure in the compiling unit 25 can be easily created using known compiler technology. However, in order to ensure that there are no errors in the calling procedure of the compiler used, it is desirable to first convert the module configuration program into the control program creation language and then compile it.

FIG. 2 shows the configuration of the compiling section 25.

The module configuration program is created by an editor on a computer using the above-mentioned module configuration description language, and is generally written in ASCII code.

Reference numeral 28 denotes a lexical analysis section, which is provided to read the module configuration program and perform lexical separation. Here, “lexical separation” means “length
It is a set of at least one character such as "h", "Joint", etc., and a word that has a unique meaning from the set is extracted from a program. Specifically, a well-known method of tracing characters using a virtual stack machine can be cited.

29 is a grammar analysis section, and a lexical analysis section 28
This is provided to interpret the resulting combination of words and phrases according to a predetermined grammar and extract necessary numerical information and the like. Specifically, this process can also use a known method of tracking tokens using a virtual stack machine.

30 is a 4-parameter extractor, which extracts "Joint to" and "E
xtend to" and "length" statements, and select "Denavit-H
This method calculates four link parameters based on the "Artenberg" notation.

Of course, a grammar may be used in which the parameters to be described are the same as these four parameters. This is because determining grammar is a geometrical element that is completely independent of other sentences, so it can be determined freely.

Reference numeral 31 denotes a mechanical/electrical system conversion parameter extraction unit, which is used to set a conversion coefficient between the mechanical system unit and the electrical system unit defined by the "Freedom" statement.

For example, the correspondence relationship between the length unit "cm" and the pulse number unit "Pulse", that is, the conversion rate is defined. However, regarding the unit system, "m" or "cm"
etc. should be unified with "mm" to avoid confusion. Generally, "mm" is often used as a unit system in determining the operating range of a robot, because it is easier to handle.

A homogeneous transformation matrix creation section 32 creates a homogeneous transformation matrix from the parameters extracted by the four-parameter extraction section 30. A homogeneous transformation matrix is a coordinate transformation matrix that collectively represents rotation and translation operations in 4 rows and 4 columns, and includes a rotation matrix and a translation vector.

In general, a position vector indicating the hand position of a manipulator with n degrees of freedom (n is a natural number) can be expressed as a function of a joint variable vector (set of joint variables) indicating the displacement of each joint. The problem of finding the hand position when a variable vector is given is called a forward kinematics problem.

Among the coordinate systems set for each joint, the relationship between adjacent coordinate systems can be defined by a homogeneous transformation matrix expressed using four link parameters.

Specifically, the homogeneous transformation matrix when the coordinate system set for the i-th joint axis is viewed from the coordinate system set for the (i-1)th joint axis has four parameters as ( θi
, αi-1, ai-1, di), and Si=sinθi
, Ci=cosθi, S(αi-1)=sinαi-1
, C(αi-1)=cosαi-1, [Math. 1]
It will take the form shown in the formula.

[0102]

[Math 1]

[0103] Such a homogeneous transformation matrix is calculated for each joint. (For details, please refer to "Computer Controlled Mechanical System Series Robot Control Fundamentals" (Corona Publishing)
See page 34. ).

[0104] Reference numeral 33 denotes an information synthesis section, which combines information regarding the conversion rate from the mechanical/electrical system conversion parameter extraction section 31 and information obtained from the homogeneous transformation matrix creation section 32 (homogeneous transformation matrix for each joint). It is provided to record the information for each arm in the arm information recording section 34.

[0105] The arm information recording section 34 collectively stores and manages information regarding each arm in the module configuration program for each arm.

[0106] If the values of all four parameters for each joint are given, by multiplying all the homogeneous transformation matrices of each joint, the hand position and posture can be expressed in a reference coordinate system fixed to the base axis. . In other words, the homogeneous transformation matrix shown in Equation [Equation 1] expresses the relative relationship between the coordinate systems set for adjacent joint axes, and it expresses the hand position in the reference coordinate system fixed to the base axis of the robot. To find the vector, it is sufficient to calculate the product of homogeneous transformation matrices for each joint, and this solves the forward kinematics problem.

The processing of multiplying the homogeneous transformation matrices recorded in the arm information recording section 34 and calculating a composite matrix of the transformation matrices is performed in the comprehensive synthesis section 35 and the forward kinematics system homogeneous transformation matrix synthesis section 36. Ru.

37 is an interface section creation section;
It is provided to create a function entry in the C language based on the degree of freedom of the joint axis specified in the above-mentioned "ROBOT" statement.

In other words, when converting a forward kinematics system (that is, converting using a homogeneous transformation matrix after synthesis), create a title part of a function that takes the number of pulses as an entry and displays its output in the Cartesian coordinate system. do.

For example, ROBOT RobotName(p1, p2, p3
)=ARM1+ARM2+ARM3 When the grammar analysis section 29 interprets the statement of the module configuration program, the interface section creation section 37 receives the interpretation result and executes DEC AxisToDec(p1, p2, p3)l.
Generates a string of on int p1, p2, p3; Here, the type "DEC" is a structure meaning a Cartesian coordinate system.

[0111] The comprehensive synthesis section 35 includes the arm information recording section 34.
A combination matrix of homogeneous transformation matrices and a conversion formula for mechanical/electrical system conversion are generated based on the information, and these and the interface section created by the interface section creation section 37 are combined to form a single transformation. Create a function.

Then, the C language compiler 38 compiles the conversion function created by the comprehensive synthesis section 35. In this case, it may be necessary to perform processing using a link locator (not shown) so that the conversion function can be operated at a specific memory location on the numerical control device.

Through the above processing, a calculation subroutine for converting the axial coordinate system to the Cartesian coordinate system regarding the forward kinematics system is created.

Next, the creation of a subroutine for calculation when converting from a Cartesian coordinate system to an axial coordinate system will be explained.

[0115] This conversion corresponds to the process of determining joint variables by giving the hand position, and the problem of determining this is called an inverse kinematics problem, and its solution methods include an algebraic or geometric solution method and a numerical method. There are known methods to solve this problem, but here we will use an algebraic solution method using inverse matrix calculations.

As described above, in the forward kinematics homogeneous transformation matrix synthesis section 36, a synthesis matrix is obtained from the homogeneous transformation matrix for each arm stored in the arm information recording section 34.

[0117] The rank calculation unit 39 checks whether an inverse matrix of the composite matrix exists. When the existence of the inverse matrix is confirmed, the generator 4 of the inverse kinematics routine
0 to that effect, and if the inverse matrix does not exist, an instruction is issued to generate a routine according to a so-called iterative calculation algorithm.

The inverse kinematics routine generation unit 40 creates an inverse transformation function based on the homogeneous transformation matrix according to instructions from the rank calculation unit 39, and generates the inverse transformation function using the C language compiler 38'.
to convert it into executable code.

In this way, a subroutine for calculation when converting from a Cartesian coordinate system to an axial coordinate system is obtained.

[0120] In creating the inverse kinematics routine, a known inverse matrix calculation program may be used.

[0121]Also, in this example, it is assumed that an inverse kinematics routine can be created, but in general, closed-form solutions cannot be obtained for inverse kinematics problems, so a conversion subroutine can always be created. Not necessarily. In this case, the value of each axis is determined by adopting a Cartesian coordinate system that includes the coordinates of specific joints and expanding the number of dimensions to (3*n) dimensions (n is a natural number). It is also an effective method to use.

The inverse matrix can also be obtained by limiting the degree of freedom in programming the module configuration program to the extent that a previously prepared inverse kinematics routine can be used.

The above processing procedure can be briefly summarized as follows.

First, an outline of the processing related to the forward kinematics system is shown below. (1) Create a module configuration program. (2) Interpret the module configuration program. (3) Extract four parameters and conversion parameters for mechanical/electrical systems. (4) Calculate a homogeneous transformation matrix for each joint. (5) Calculate a composite matrix of homogeneous transformation matrices. (6) Create a calculation subroutine.

[0125] Also, an outline of the processing related to the inverse kinematics system is shown below. (1) Check the existence of an inverse matrix for the homogeneous transformation matrix. (2) Solve the inverse kinematics problem using inverse matrix calculation. (3) Create a calculation subroutine.

[0126] Through the above processing, the coordinate transformation unit 9, which is a collection of subroutines, is obtained.

Note that the tool subroutine unit 10 can also be created by following the same steps as the steps for creating the coordinate transformation unit 9.

[0128] It is of course possible to incorporate these created units into the numerical control device 2 after converting them into ROM, but it is preferable to store them in readable/writable RAM to increase processing flexibility. is desirable.

[0129] Furthermore, the conversion unit created on the module configuration programming unit 23 is
7, the coordinate conversion unit 9 in the numerical control device 2 is transferred via the LAN trunk line 7. Since the entry point is determined in advance, the robot 1 can be controlled within the numerical control device 2 immediately upon completion of the transfer.

[0130]

Effects of the Invention As is clear from the above description, according to the present invention, even if the link configuration of a robot is frequently changed in an FMS, the module configuration program that describes the link structure can be changed. This allows the robot program to be handled without any modification, and the effort required for program management and maintenance can be reduced.

[0131] Furthermore, when creating a robot program, it is possible to create it without being aware of the shape of the tool, and even if the design of the tool is changed, there is no need to change the description of its operation. Tool changes can be accommodated by creating completely independent modular configuration programs,
Robot programs can now be programmed in a separate department from the tool design department.

[0132] In the numerical control device of the robot, a storage area for conversion programs (coordinate conversion unit and tool subroutine unit) is provided independently of the program storage area for describing the control procedure, and a storage area for conversion programs (coordinate conversion unit and tool subroutine unit) is provided. By making it possible to write from the outside at any time, you can make better use of the network (
For example, CAD data can be used during programming, etc.), and programs can be created efficiently.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of the construction of a robot system.

FIG. 2 is a block diagram showing the configuration of a compiler section.

FIG. 3 is a diagram conceptually showing the configuration of a coordinate transformation unit.

FIG. 4 is a diagram conceptually showing the configuration of a tool subroutine unit.

FIG. 5 is a side view schematically showing an example of a link structure of a robot.

[Explanation of symbols]

1 Multi-axis robot 2 Numerical control section 6 Control program storage section 9, 10 Conversion program storage section 23 Programming section

Claims (2)

[Claims] 1. A control device for a multi-axis robot that can freely change the link structure, comprising: (1) creating a program that describes the link structure of the multi-axis robot; Information indicating the displacement and posture of each joint of the robot, based on parameters indicating the relative positional relationship between the coordinate systems set in each case, and reference coordinates that fix the position of the robot's hand to a specific joint axis of the robot. A programming unit is provided to generate a conversion program for mutually performing coordinate conversion with the information expressed in the system, and convert it into command words that can be operated by the numerical control unit of the robot. 2) Store the conversion program generated by the programming unit, and use the conversion program to obtain hand position information from information indicating the state of each joint of the robot or information indicating the state of each joint obtained from the hand position. 1. A control device for a multi-axis robot, comprising a numerical control section that controls positioning of the robot based on the following. 2. The control device for a multi-axis robot according to claim 1, wherein the numerical control section includes a storage section for a conversion program independently of a control program storage section that stores a program that describes the control procedure. in a predetermined position,
A control device for a multi-axis robot is further characterized in that a conversion program can be written from outside at any time.