JP2000271885A - Position controller for robot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a position controller for industrial robot, capable of being manufactured at a relatively low cost with high potential precision. SOLUTION: When the spatial position coordinate of a robot is controlled, a microprocessor 2 computes the command value (command position) of the spatial position coordinate of the robot using a control program called from a memory 4, converts the command position into the drive amounts of respective actuators (target drive amount), and computes a correction value corresponding to the value of the target drive amount using a correcting expression called from a memory 6. The correction value is added to the value of the target drive amount, and the command value of the drive amount is determined and given to the respective actuators 1, thereby controlling the drive amounts of the respective actuators 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position control system for an industrial robot, and more particularly to an improvement in the position accuracy of the industrial robot.

[0002]

2. Description of the Related Art FIG. 4 shows an outline of a positioning mechanism in a conventional general robot control system, and FIG. 5 shows a control block diagram for each actuator.

In FIG. 4, 1 is an actuator (for example, an electric motor), 2 is a microprocessor for controlling the actuator based on a control program, 3 is a memory for storing a system program for interpreting and executing the control program, and 4 is a control. A memory 5 stores a program (user program) and a work memory 5 stores data and calculation results.

[0004] An operator creates a control program for instructing the procedure of moving the spatial position coordinates of the robot in advance,
This is input to the memory 4. When the robot performs an actual operation, the microprocessor 2 calls a control program from the memory 4 and calculates a command value (command position) for the spatial position coordinates of the robot using the control program. Further, as shown in FIG. 5, the microprocessor 2 converts the command position into the drive amounts of the actuators 1a and 1b, and gives these drive amounts to the actuators 1 as command values. Each actuator 1 is controlled by a given command value.

Conventionally, in order to improve the position accuracy of an industrial robot, the absolute position accuracy has been improved by increasing the processing accuracy and assembly accuracy of the components. Since such a method inevitably involves an increase in manufacturing cost, it has been difficult to realize a robot having high positional accuracy at a low price. Further, there is a limit to the improvement of the positional accuracy only by improving the processing accuracy and the like.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of improving the positional accuracy of the conventional industrial robot, and an object of the present invention is to provide a high-precision industrial robot. It is another object of the present invention to provide a position control device for an industrial robot that can be manufactured at a relatively low cost.

[0007]

According to the present invention, there is provided a position control device for a robot, wherein an actuator provided for each axis of the robot and a control program for designating a command position for a spatial position coordinate of the robot are stored. A memory device, a command position for a spatial position coordinate of the robot is calculated using the control program, and then the first calculation means for converting the command position to a target drive amount of each actuator; (Ii) calculating means and, for the drive amount of each actuator, a correction value to be added to the command value in order to remove an error between the command value and the actual value of the drive amount of each actuator when the command value is given. A second memory device in which a correction formula to be calculated for each actuator is stored, wherein the second arithmetic unit is sent from the first arithmetic unit. A value is obtained by adding a correction value calculated by using the correction formula corresponding to the target drive amount to the target drive amount of each actuator, and this value is given to each actuator as a command value to control each actuator. It is characterized by the following.

According to the robot position control device of the present invention, data on an error between a command value given to each actuator and an actual drive amount (actual value) is previously collected for the drive amount of each actuator. Then, based on the data, a correction value to be added to the command value in order to eliminate the error is obtained, and a correction formula for calculating the correction value is created for each actuator.

In the actual operation, when controlling the drive amount of each actuator, first, the first calculating means calculates a command position for the spatial position coordinates of the robot using a control program, and further calculates the command position. Is converted into a target drive amount of each actuator, and the target drive amount is sent to the second calculating means. The second calculating means calculates a correction value corresponding to the target drive amount by using the correction formula, and gives a value obtained by adding the correction value to the value of the target drive amount to each actuator as a command value. To control each actuator.

According to the robot position control device of the present invention, a high specification is not required for the machining accuracy and the assembly accuracy of the components of the robot, so that a robot having high position accuracy can be realized at a low price. .

[0011]

FIG. 1 shows a schematic configuration of a robot position control device according to the present invention. In FIG. 1, 1 is an actuator (for example, an electric motor), 2 is a microprocessor (first operation means and second operation means) for controlling the actuator based on a control program or the like, and 3 is a computer for interpreting and executing the control program or the like. A memory for storing a system program, 4 is a memory (first memory) for storing a control program (user program), 5 is a work memory for storing data and calculation results, 6 is a memory for storing a correction formula and a correction table (first memory). Two memories).

FIG. 2 shows the relationship between the spatial position coordinates of the robot and the driving amounts of the actuators provided for each axis. The spatial position coordinates of the robot are determined by a combination of the drive amounts of the actuators. Note that the robot spatial position coordinates include the robot posture.

FIG. 3 shows a control block diagram for the actuator.

The command position of the robot calculated using the control program is converted into a drive amount (a target drive amount) for each actuator. A correction value corresponding to the target drive amount of each actuator is calculated based on a correction formula, and the calculated correction value is added to the value of the target drive amount to obtain a command value for the drive amount of each actuator. Each actuator is controlled by the command value thus obtained.

The above-described correction formula is created in advance in the following procedure and is input to the memory 6 (FIG. 1). That is, for the drive amount of each actuator, data on an error between the command value given to each actuator and the actual drive amount (actual value) is collected. On the basis of the data, correction values to be added to the above-mentioned command values for eliminating the above-mentioned errors for each actuator are summarized in the form of a correction table. Further, a correction formula for calculating a correction value from the command value is created based on the correction table. These correction tables and correction formulas are stored in the memory 6 (FIG. 1).

The operation of the position control device shown in FIG. 1 will be described.

Before the actual work is performed using the robot, an operator creates a control program (user program) for designating the spatial position coordinates of the robot according to the work content, and inputs the control program to the memory 4. deep.

When controlling the spatial position coordinates of the robot in actual work, first, the microprocessor 2
Calculates a command value (command position) for the spatial position coordinates of the robot using the control program called from, and then converts the command position into a drive amount (target drive amount) of each actuator.

Next, the microprocessor 2 calculates a correction value corresponding to the value of the target drive amount by using the correction formula called from the memory 6. The correction value is added to the value of the target drive amount to obtain a command value for the drive amount, and the command value is given to each actuator 1 to control the drive amount of each actuator 1.

[0020]

According to the position control device for a robot of the present invention, each actuator provided for each axis of the robot is corrected by a command value of the drive amount in accordance with a correction formula prepared in advance, whereby each actuator is controlled. Of the drive amount with respect to the target value can be improved.

According to the robot position control device of the present invention, a high specification is not required for the processing accuracy and the assembly accuracy of the components of the robot, so that a robot having high position accuracy can be realized at a low price. .

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a robot position control device according to the present invention.

FIG. 2 is a diagram illustrating a relationship between spatial position coordinates of a robot and a driving amount of an actuator provided for each axis.

FIG. 3 is a control block diagram for each actuator in the robot position control device according to the present invention.

FIG. 4 is a diagram showing an outline of a positioning mechanism in a conventional robot control system.

FIG. 5 is a control block diagram for each actuator in a conventional robot control system.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Actuator 2 ... Microprocessor (1st calculating means and 2nd calculating means) 3 ... Memory 4 ... Memory (1st memory) 5 ... Work memory 6 ... ..Memory (second memory).

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masahiro Watanabe 2068-3 Ooka, Numazu-shi, Shizuoka Prefecture F-term in Numazu Works (reference) 3F059 DA08 FB15 5H269 AB33 BB03 EE05 EE11 FF06 GG08 NN02 5H303 AA10 BB03 BB08 CC01 DD01 EE03 EE07 FF03 HH04 HH07 MM05 9A001 BZ03 BZ04 HH34 JJ49 KK32 KK54

Claims (1)

[Claims] An actuator provided for each axis of a robot, a first memory device storing a control program for instructing a command position for spatial position coordinates of the robot, and a spatial position of the robot using the control program Calculating a command position for the coordinates, and then converting the command position into a target drive amount of each actuator; a second calculation means for controlling each actuator; and a command value for the drive amount of each actuator. And a second memory device for storing a correction formula for calculating a correction value to be added to the command value for each actuator in order to remove an error between the actual value of the drive amount of each actuator when the command value is given. The second operation means, the target drive amount of each actuator sent from the first operation means, the target drive The calculated values obtained by adding the calculated correction value using the correction equation, the position control device of the robot and controls each actuator by applying to each actuator this value as a command value in response to.