JPH0243602A - Method for correcting mechanical error of robot - Google Patents

Abstract

PURPOSE:To prepare a program for plural robot actions with the same standard action data by preparing a program for the robot actions of a robot based on the standard action data corrected by the stored mechanical error quantity data. CONSTITUTION:The error quantity of the mechanical system of a robot is actually measured, stored into a storing means and the machine specifications of the robot are stored. The standard action data of the robot are converted from a work coordinate system to a robot coordinate system and the converted standard action data are corrected by the data stored in the storing means. Consequently, when respective data stored in the storing means are changed, the standard action data after they are converted in accordance with respective data are corrected. Thus, with single standard action datum, the program for the action of plural robots can be prepared by an off-line teaching system.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for correcting errors in a mechanical system of a robot, and in particular, when creating a robot operation program using an offline teaching system, the present invention relates to a method for correcting errors in a mechanical system. The present invention relates to a method for correcting mechanical system errors of a robot, which corrects standard motion data of the robot.

[Conventional technology]

Generally, when a robot operation program is created by teaching, the robot is actually moved and operation data is collected, so there is no need to take mechanical system errors into consideration when creating the program. However, when creating a program using offline teaching, the robot is not actually moved to collect motion data, but standard motion data is calculated in advance based on a mathematical model, so errors in the mechanical system are not taken into account. must be created.

That is, when creating a program by off-line teaching, the standard operation data must be corrected in consideration of errors in the mechanical system. Conventionally, a known method for this correction is to measure mechanical system errors in one robot at regular intervals, and to interpolate this measured data using an interpolation method using a linear approximation formula. (For example, Japanese Patent Application Laid-open No. 198902/1983).

[Problem to be solved by the invention]

However, the conventional correction method is suitable for creating a robot motion program for one robot, but when creating robot motion programs for multiple robots using the same standard motion data. There is a problem. For example, if the robot is a multi-axis lathe,
Differences occur in mechanical system errors such as multi-axis positioning errors and squareness errors for each lathe. Therefore, with the same correction method as described above, there is a problem that the work cannot be machined with the same finishing accuracy on each lathe. On the other hand, in order to machine workpieces with the same precision, it is necessary to reteach each lathe. However, this poses a problem in that the setup time becomes long and the operating rate decreases.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a mechanical system error correction system for robots that solves the problems of the conventional techniques described above and that makes it possible to create robot operation programs for a plurality of robots using the same standard operation data. The purpose is to provide a method.

[Means to solve the problem]

In order to achieve the above object, the present invention includes a storage step of storing the actually measured error amount of the robot's mechanical system and the robot's mechanical specifications in a storage means, and a calculation means of calculating standardized standard operation data of the robot. a calculation stage for calculating;
A correction step of converting the standard movement data of the robot from the workpiece coordinate system to the robot coordinate system and correcting the converted standard movement data with the data stored in the storage means; The present invention is characterized by comprising a creation step of creating a robot operation program for the robot based on the robot operation program, and an operation step of operating the robot based on the robot operation program.

[For production]

According to the present invention, first, the amount of error in the mechanical system of the robot is actually measured, and this measurement data is stored in the storage means, and the mechanical specifications of the robot are also stored in the storage means. Next, by off-line teaching, standardized standard motion data for the robot is calculated based on the mathematical model. As this standard motion data, a single standard motion data is used even when a plurality of robots are operated. Also,
The standard motion data of the robot is converted from the workpiece coordinate system to the robot coordinate system, and the converted standard motion data is corrected with data stored in the storage means. Therefore, by changing each data stored in the storage means, the converted standard operation data is corrected in accordance with each data. Then, a robot operation program for the robot is created based on this corrected standard operation data, and the robot is operated based on this robot operation program.

〔Example〕

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Before describing one embodiment of a method for correcting mechanical errors in a robot according to the present invention, an example of the configuration of a robot will be described below with reference to the accompanying drawings.

FIG. 1 shows a robot 1 with five axes of movement. The five axes of movement of this robot 1 are an X-axis and a Y-axis that are parallel to the table 2 that fixes the workpiece, a Z-axis that is perpendicular to the table 2, and an A-axis that rotates around the Z-axis. , and the B axis rotating around the Y axis. Hereinafter, the coordinate system constituted by these five movement axes will be referred to as a robot coordinate system.

In addition, on the top surface of table 2 there is a reference shaft (
X' axis, Y' axis) are provided. Hereinafter, the coordinate system constituted by these reference axes will be referred to as a workpiece coordinate system.

FIG. 2 shows a state in which a tool 5 is attached to the tool attachment portion 3 of the robot 1. Hereinafter, the intersection O between the A-axis rotation center Ll and the Bf [11 rotation center L2 in this mounting portion 5] will be expressed as
It is called an operating point.

This operating point O and the tip of the tool 5 are
Assuming that the tool 5 is on the Z-axis center line when returning to the origin, the length g from the operating point O to the tip of the tool 5 in this case will be hereinafter referred to as arm length.

Next, an example of a method for correcting mechanical errors in a robot will be described.

First, as errors in the mechanical system, errors in the workpiece coordinate system, positioning errors in the X and Y axes, straightness errors in the X and Y axes, and straightness errors between the X and Y axes are actually measured. These errors are measured because they are the main error factors of the robot 1.

These errors also measure the error at operating point 0.

As shown in FIG. 3(a), the n1 constant of the error in the workpiece coordinate system is determined based on the origin position of the workpiece coordinate system in the robot coordinate system, the vector in the X-axis direction, and the hector in the Y-axis direction. Then, a coordinate transformation matrix is created based on this measurement result.

To measure the positioning error of the X-axis and Y-axis, as shown in Fig. 3(b), move the tip of the tool 5 of the robot 1 in the Measure positioning error.

As shown in Fig. 3(e), the n1 constant of the straightness error of the X-axis is determined by moving the tip of the tool 5 of the robot 1 in the X-axis direction at the same pitch as when measuring the positioning error. X
Measure the deviation in the Y-axis direction with respect to the axis.

The measurement of the straightness error of the Y-axis and the straightness error between the The error in the X-axis direction in the deviation in the Y-axis direction from the virtual X-axis at the time of measuring the X-axis straightness is measured. This error includes the straightness of the Y axis and the squareness between the X and Y axes.

FIG. 3(e) shows a composite of the errors in FIGS. 3(a) to 3(d) described above. As is clear from the figure (e), the error in the X-axis direction at a given position is the X-axis positioning error ρI, the Y-axis straightness error, and the X-Y axis straightness error ρ4. be synthesized. Also,
As for the error in the Y-axis direction, the Y-axis positioning error ρ2 is
The shaft straightness error ρ3 is synthesized. Note that errors that are negligible are not combined.

Next, the error data of the mechanical system measured as described above is stored in the storage device of the offline teaching system.

FIG. 4 shows the configuration of the offline teaching φ system.

This system includes a storage device 1o that stores the amount of error of the mechanical system and machine specifications that have been actually measured in advance, and a tool position calculation that calculates standard operation data such as the tip position of the tool 3 and the tool axis vector based on a mathematical model. Device 11 (e.g. APT
), and a program creation device 12 that creates a robot operation program based on the data from the re-device 10゜]1.
and a program storage and transfer device 15 that stores the program data from the creation device 12 and transfers it to the robot controller 13 and further to a group of robots 1 beyond that.

Next, in the robot operation program creation device 12,
A robot operation program is created by correcting the actually measured error data to the standard operation data from the tool position calculation device 11 that has been taught offline.

Note that the correction is performed by interpolating between predetermined measurement pitches using a linear equation, as shown by the solid line in FIG.

Furthermore, depending on the characteristics of the error, it is also possible to perform interpolation using a quadratic or higher order equation as shown by the broken line.

FIG. 6 is a flowchart showing the procedure for the above correction.

First, manually calculate the amount of deviation of the workpiece coordinate system from the robot coordinate system and create a coordinate transformation matrix for correction (
Step 1).

Next, mechanical error data such as positioning errors and mechanical specifications necessary for correction are input and initialized (step 2).

After the initialization is completed, standard operation data such as the tool tip position and tool axis vector calculated by the tool position calculation device 11 are input (step 3).

Next, using the coordinate transformation matrix created in step 1, standard motion data such as the tool tip position and tool axis vector are transformed from the workpiece coordinate system to the robot coordinate system. Then, the deviation of the coordinate system is corrected (step 4).

Next, operating point 0 is calculated based on the converted standard operation data such as the tool tip position and tool axis vector (step 5).

Correct the position of operating point 0 based on mechanical system errors such as positioning error of the X wheel and Y axis, straightness error of the X axis and Y axis, and squareness error between the X and Y axes (
Step 6). If correction regarding the Z axis is necessary, make the correction at this stage.

Next, the tool tip position and tool rotation angle are calculated based on the corrected operating point O position and tool axis vector, and output as the tool tip position of the robot operation command (step 7). If correction regarding the A-axis or B-axis is required, it is corrected at this stage.

Further, steps 3 to 7 are repeated, and when the input standard operation data from step 3 is no longer present, the correction process is terminated at that point.

Next, the program corrected in this way is transferred to the robot controller 1 via the program storage and transfer device 15.
3, and further to a group of robots 1 beyond that.

Then, the robot 1 operates based on the corrected program.

According to this embodiment, if each data of mechanical system errors and machine specifications is manually input in steps 1 and 2, the standardized standard operation data is corrected according to the amount of error and automatically A robot operation program is created.

Therefore, when operating robot 1 of - group, all you need to do is change the mechanical system error and mechanical specification data input values of robot 1 in steps 1 and 2, and teach each robot 1 individually. There is no need to make any repairs (therefore, it is possible to shorten machining setup time and improve operation rate).

〔Effect of the invention〕

As is clear from the above description, according to the present invention, the actual N
A storage step in which the determined error amount of the robot's mechanical system and the mechanical specifications of the robot are stored in a storage means, a calculation step in which standardized standard operation data of the robot is calculated by a calculation means, and standard operation data of this robot. a correction step of converting from the workpiece coordinate system to the robot coordinate system and correcting the converted standard motion data with the data stored in the storage means; and based on the corrected standard motion data, Since it has a creation stage for creating a program and an operation stage for operating the robot based on this robot operation program, when creating operation programs for multiple robots using an offline teaching system, each robot can be By simply storing the mechanical system error amount, machine specifications, etc. in the storage means, it is possible to create a robot operation program in which the standard operation data is corrected using a single standard operation data.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the schematic configuration of a robot showing an embodiment of the mechanical system error correction method according to the present invention, FIG. 2 is a side view showing the tool attachment part of the robot, and FIGS.
e) is also an explanatory diagram showing the mechanical system error of the robot, the fourth
FIG. 5 is a block diagram showing the offline teaching system, FIG. 5 is an explanatory diagram showing errors in the mechanical system of the robot, and FIG. 6 is a flowchart explaining the robot operation program. 1...Robot, 2...Table, 5...Tool,
10...Storage device, 11...Calculation device, 12...
Robot motion layer program creation device, 13... robot controller. Applicant's agent Mr. Sato (C) (b) (d) (e)

Claims (1)

[Claims] a storage step of storing the actually measured error amount of the robot's mechanical system and the mechanical specifications of the robot in a storage means; a calculation step of calculating standardized standard operation data of the robot by a calculation means; and a calculation step of calculating the standardized standard operation data of the robot. a correction step of converting from the workpiece coordinate system to the robot coordinate system and correcting the converted standard motion data with the data stored in the storage means; and based on the corrected standard motion data, A method for correcting errors in a mechanical system of a robot, comprising a creation step of creating a program and an operation step of operating the robot based on the robot operation program.