JP2002127054A - Robot mechanism calibration calculation method and robot mechanism calibration calculation system - Google Patents

Abstract

(57) [Problem] To effectively reflect a mechanism calibration when a control point other than a calibration point and a plurality of working effectors are used. SOLUTION: There is provided a work effector correction storage means 10 for storing a correction value related to a calibration point on the work effector among the robot calibration correction values obtained by a calculation device 2 in association with a name of the work effector, The mechanism calibration value determined for the calibration target point is recorded as the mechanism calibration value of the work effector. As a result, the robot mechanism correction value required for the calibration target point set on the work effect device can be treated as a correction value for the work effect device, and the correction effect is reflected on the entire work effect device. Therefore, it is possible to shorten the calibration operation time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a robot mechanism calibration calculation method for a robot mechanism element and a robot mechanism calibration calculation system for accurately controlling the tip position of an industrial robot performing various operations.

[0002]

2. Description of the Related Art In general, industrial robots have errors in machining and assembly at the joint angle origin and tool length. Therefore, when calculating the position coordinates of the robot tip from the joint angle information of the robot, an error occurs between the coordinates calculated based on the design values and the actual position.

In order to eliminate this position error,
A robot mechanism calibration calculation method has been developed for correcting the origin position of the robot joint and the length of each link, which are the mechanism errors of the robot. This is to calculate the mechanism error by measuring the joint angle and tip position of the robot, and to reflect the mechanism error in the calculation model,
An attempt is made to approximate the movement of the actual robot and the movement of the model robot.

FIG. 6 shows an example of a block diagram of a conventional robot mechanism calibration calculation system. That is, the robot mechanism calibration calculation system is generally configured in a robot controller, and includes a robot operation program storage unit 1, a calculation device 2, a robot information input unit 3, a robot operation control unit 4, and a robot operation output unit. Means 5,
It comprises a robot teaching input means 6, a robot mechanism parameter storage means 7, a robot calibration data storage means 8, and a program storage means 9.

More specifically, the robot operation program storage means 1 is a means for storing an operation program of an operation performed by the robot, and also stores an operation program for instructing the movement of the robot necessary for performing a calibration operation. It is stored here. The arithmetic unit 2 is a part for performing various calculations necessary for operating the robot, such as creating position commands, and the calibration calculation of the robot is also executed in this part. The robot information input means 3 inputs robot internal information such as pulse data of an encoder attached to a robot joint (not shown). The robot operation control means 4 is a part for performing a servo operation for controlling the movement of a motor for operating the robot, and includes encoder pulse data from the robot information input means 3 and operation instruction commands from the arithmetic unit 2. Then, the necessary servo control is performed. The robot operation output means 5 is an interface between the controller and the robot main body, and transmits the result of the robot operation control means 4 to a motor for operating a robot (not shown). The robot teaching input means 6 is an interface for instructing a robot to operate the robot from an operator, and performs, for example, input monitoring from a teaching pendant. The robot mechanism parameter storage unit 7 is a part for storing design values for parameters related to the robot mechanism required for the robot operation, and is used for conversion from joint angles to robot tip positions and for inverse conversion. The robot calibration data storage unit 8 is a unit that stores a corrected correction value of a robot mechanism parameter that is an actual value, and stores a correction value after a calibration operation is performed. The program storage means 9 is a part for storing a robot control program executed by the arithmetic unit 2, and also stores a program for performing a calibration operation of the robot mechanism.

When calibrating a robot mechanism error using such a system, one point to be calibrated is specified on a work effector or a dedicated jig. As the robot tip coordinates, a parameter is input from the robot mechanism parameter storage means 7 so that a coordinate value for the point is obtained. Then, a robot operation is commanded by the robot teaching input means 6, and the relationship between the joint angle and the robot tip coordinates is measured. The measurement result is sent to the arithmetic unit 2, and the robot mechanism element is calculated so as to minimize the error between the position calculated from the joint angle and the actual position of the tip. To memorize.

[0007]

As in the prior art described above, in the calibration of a robot mechanism, an arbitrary point is designated, and a mechanism correction value at which the relationship between the joint angle and the coordinate value becomes optimal at that point is specified. Is what you want. By the way, in actual work, a plurality of work effectors are often used without fixing the work effector to be used. Since the robots used for such work differ in the points to be calibrated for each work effector, it is necessary to perform calibration work for each work effector, and many man-hours are required. Further, when a position having no actual object, such as a center position grasped by a hand, is set as a work point, a calibration target point cannot be set there, and thus calibration cannot be performed.

[0008] In this case, the work effector refers to a tool attached to the end of the robot arm and actually performing work, such as a welding torch or a laser torch. As described above, when performing the robot operation by replacing each device, it is necessary to perform calibration each time since the work point is different for each device. Also, when grasping an object with a hand,
The center position (working point) is not clear and cannot be calibrated as it is.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention has been made in view of the above points, and when performing a mechanical error correction of a robot performing an actual work using a work effector, a control other than a calibration point is performed. It is an object of the present invention to provide a robot mechanism calibration calculation method and a robot mechanism calibration calculation system capable of equally correcting a mechanism error when using a point and a plurality of working effectors.

[0010]

According to a first aspect of the present invention, there is provided a robot mechanism calibration calculation method comprising the steps of: attaching a work effector to a tip of a robot; A robot mechanism calibration calculation method for calibrating a mechanism parameter of a joint angle, an origin, and a link length of a robot that determines a relationship between robot tip coordinate information, wherein a mechanism calibration value obtained for a calibration target point is determined by a work effect. It is recorded as a mechanism calibration value of the calibration target point viewed from the mounting surface of the instrument, and is calibrated by a coordinate transformation matrix.

As described above, the mechanism calibration value obtained for the calibration target point is recorded as the mechanism calibration value of the calibration target point viewed from the work effector mounting surface, and is calibrated by the coordinate conversion matrix. The robot mechanism correction value obtained for the calibration target point set above or the like can be treated as a correction value for the work effector. For this reason, since the correction effect can be reflected on the entire work effect device, the calibration work time can be reduced.

According to a second aspect of the present invention, there is provided a robot mechanism calibration calculation method according to the first aspect, wherein a plurality of mechanism calibration values of a work effector mounting surface can be recorded for one robot, and the work effector is changed. Sometimes, a mechanism calibration value corresponding to each work effector can be used.

As described above, it is possible to record a plurality of mechanism calibration values on the work effector mounting surface for one robot, and when the work effector is changed, the mechanism calibration value corresponding to each work effector is changed. Since the value is available, even if you work while replacing multiple work effectors,
A correction value can be set for each work effect device, and an optimum correction value can be given to each. As a result, the accuracy can be improved, and the work efficiency can be improved.

According to a third aspect of the present invention, there is provided a robot mechanism calibration operation system, comprising: a robot operation program storage means for storing an operation program of an operation performed by the robot; an operation device for performing various operations for operating the robot; Robot mechanism parameter storage means for storing design values for parameters related to the mechanism, and robot calibration data storage means for storing calibrated correction values of parameters relating to the robot mechanism, which are actual values; A robot mechanism calibration operation system for calibrating the mechanism parameters from the robot mechanism parameter storage means for determining the relationship between the tip coordinate information of the robot mechanism and the robot calibration data storage means and storing the mechanism parameters in the robot calibration data storage means. Robot calibration correction value A work effector correction value storage means for storing a correction value related to a calibration point on the work effector attached to the tip of the robot in association with the name of the work effector, and storing a mechanism calibration value obtained for the calibration target point. , Recorded as the working effector mechanism calibration value.

As described above, of the robot calibration correction values obtained by the arithmetic unit, the correction value relating to the calibration point on the work effector attached to the end of the robot is stored in association with the name of the work effector. Since the mechanism calibration value obtained for the calibration target point is recorded as the mechanism calibration value of the work effector, it is obtained for the calibration target point set on the work effector or the like. The robot mechanism correction value can be handled as a correction value for the work effector. For this reason, the correction effect can be reflected on the entire work effect device as in the first aspect, and the calibration work time can be shortened.

According to a fourth aspect of the present invention, there is provided a robot mechanism calibration operation system according to the third aspect, wherein the data stored in the work effector correction value storage means is used to set a calibration correction value corresponding to the work effector name as a key. Is selected, and a plurality of mechanism calibration values of the work effector can be recorded for one robot. When the work effector is changed, the work effector can be changed. Mechanism calibration values can be used.

As described above, the work effector selecting means for selecting the calibration correction value corresponding to the name of the work effector from the data stored in the work effector correction value storage means, It is possible to record a plurality of mechanism calibration values for a robot, and to use a mechanism calibration value corresponding to each work effector when the work effector is changed. Even when the work is performed while replacing the effector, it is possible to set a correction value for each work effector, and it is possible to give an optimum correction value to each. As a result, the accuracy can be improved as in the case of the second aspect, so that the work efficiency can be improved.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram showing a robot mechanism calibration calculation system for carrying out the first embodiment of the present invention. A robot mechanism calibration operation system embodying the present invention is realized on, for example, a robot controller, and as shown in FIG. 1, a robot operation program storage unit 1, an arithmetic unit 2, a robot information input unit 3, a robot operation control unit 4, a robot operation output means 5, a robot teaching input means 6, a robot mechanism parameter storage means 7, a robot calibration data storage means 8, a program storage means 9, and a work effector correction value storage means 10. Do it. Steps 1 to 9 are the same as in the conventional example, and a description thereof will be omitted.

The work effector correction value storage means 10 stores the correction value related to the calibration point on the work effector among the robot calibration correction values obtained by the arithmetic unit 2 in association with the name of the work effector. It is. The correction value relating to the robot arm body is stored in the robot calibration data storage means 8 as in the conventional case.

When the robot is operated using the correction data, the correction value of the robot arm stored in the robot calibration data storage means 8 and the work effector stored in the work effector correction value storage means 10 are used. The conversion of the joint angle and the robot tip position is performed using the correction data of the work effector stored in the robot.

Thus, even when the control point during the operation of the robot is different from the calibration point, it is possible to perform an accurate operation using the calibration correction value obtained for the work effector.

Here, the relationship between the joint angle and the tip position of the robot is expressed by linking a coordinate transformation matrix at each joint. The coordinate transformation matrix defines the transformation of a coordinate system set before and after the joint using information on the angle of the joint and the length of the link. Here, the coordinate conversion matrix from the (n-1) th link to the nth link is ^n-1 _An , and the link length is expressed as (Lx, Ly, Lz) in the xyz coordinate system.
If the angle is θ at the joint about the x-axis, the transformation matrix element is (Equation 1).

[0023]

(Equation 1)

A transformation matrix for each joint is defined based on the link length and the rotation axis. Then, in a normal robot having a quasi-number of joints, the coordinates from the robot origin to the tip are calculated by integrating the conversion matrix. For example, in the case of a vertical articulated robot having six joints, obtaining the tip position from the joint angle is a product of six transformation matrices, and is represented by (Equation 2).

[0025]

(Equation 2)

Here, represents the integration of the matrix. P is a four-dimensional matrix composed of (X, Y, Z, 1) ^T. X,
Y and Z are the tips of the robot, and 1 is a fixed value for calculation. The suffix T of the matrix indicates that the matrix is transposed. The contents of each transformation matrix depend on the actual robot structure.

If the joint angles of the six axes are θ ₆ at the coordinates (Px, Py, Pz) of the calibration point as viewed from the work effector mounting surface, and the rotation axis is the X direction, the matrix ⁵ A ₆ becomes , (Equation 3).

[0028]

(Equation 3)

In the calibration calculation, a correction value of the angle and the link length is calculated so that the relationship between the joint angle and the tip position calculated by (Equation 2) becomes accurate. For example, assuming that (dx, dy, dz) is obtained as a correction value related to the link length, the link length of the corresponding transformation matrix is represented by Lx + dx, L
Correction is performed by setting y + dy and Lz + dz. As for the angle, correction is performed on the set joint angle.

When a work effector is attached to the end of the robot and a calibration operation is performed on one point p1 on the work effector, it is equivalent to treat P1 viewed from the end of the robot arm as the final link. Therefore, when calibration is performed,
The correction value dP = (dPx, dPy, dPz) is obtained for the coordinate P = (Px, Py, Pz) of P1 as viewed from the work effect device mounting surface (flange surface) coordinate system to the robot. In equation (2), so that Lx is an element of the link in the ⁵ A ₆ matrix, Ly, the correction value for Lz obtained.

In the embodiment of the present invention, a virtual joint n + 1 is added between the robot and the work effector. And
Data relating to the position of the calibration point corresponding to a link length of the robot shall be set in the transformation matrix ⁶ A ₇ of the new joint. Then, it sets the data relating to correction of the obtained tool part by calculating a length element of ⁵ A _6. Elements relating to rotation of the ⁶ A ₇ matrix is fixed as a basic matrix does not involve actual rotation. That is, for the tool part, the model data and the obtained correction value are
Describe with another transformation matrix.

As a result, the coordinate conversion formula when the present invention is used is expressed as (Equation 4).

[0033]

(Equation 4)

Therefore, as viewed from the work effector mounting surface,
When (dPx, dPy, dPz) is obtained as a correction value at the coordinates (px, Py, Pz) of the calibration point, ⁵ A ₆ and ⁶ A ₇ of (Equation 3) are respectively expressed by (Equation 5). , (Equation 6)
Becomes

[0035]

(Equation 5)

[0036]

(Equation 6)

When the control point is changed in the work effector, only the part (Px, Py, Pz) shown by (Equation 6) indicating the coordinates from the origin of the coordinate system of the work effector to the control point is obtained. Be changed. Equation (5) (dPx, dPy, dP) obtained as a correction value for the attachment of the work effector to the robot.
The value of z) is not changed. Therefore, it is possible to commonly correct all points on the work effector.

[0038] ⁵ A ^₆ · ₆ A ₇ portion only accumulation of so be expressed as (Equation 7) can be considered as ⁵ A ₆ in a conventional equivalent.

[0039]

(Equation 7)

Therefore, by calculating (Equation 7) in advance,
The conversion of the joint angle and the tip coordinates can be handled in the same manner as the conventional robot mechanism correction method.

A second embodiment of the present invention will be described with reference to FIGS. FIG. 2 is a block diagram showing a robot mechanism calibration calculation system for carrying out the second embodiment of the present invention.

A robot mechanism calibration calculation system embodying the present invention is realized, for example, on a robot controller. As shown in FIG. 2, a robot operation program storage means 1, a calculation device 2, a robot information input means 3,
Robot operation control means 4 and robot operation output means 5
A robot teaching input means 6, a robot mechanism parameter storage means 7, a robot calibration data storage means 8, a program storage means 9, and a work effector correction value storage means 10
And a work effect device correction value selecting means 11. 1
Steps 9 to 9 are the same as in the conventional example, and the description is omitted.

In this embodiment, the work effect device correction value storage means 10 stores a correction value for the work effect device in a table format in association with the name of the work effect device. Then, in order to store a plurality of the associations, a structure as shown in FIG. 3 is provided. The work effect device correction value selection unit 11 reads the data stored in the work effect device correction value storage unit 10
Using the name of the work effector as a key, a corresponding calibration correction value is selected. If there is data that matches the name of the work effector attached to the robot, the correction value is returned. If there is no match, 0 is returned as the correction value.

Thus, even when the work effector is changed during the work, the correction operation can be performed by selecting the optimum calibration correction value corresponding to the work effector.

FIG. 4 is a flow chart of a robot mechanism calibration calculation method according to a second embodiment of the present invention. A method for calculating a joint angle and a tip position using a correction value when a correction value for a work effector has been set will be described. Hereinafter, S
The numerical value following "" indicates a step number.

First, in the initial state of the robot operation, it is checked whether a correction value has been set for the set work effector (S1). If the correction value is set,
The corresponding correction value is read (S2). The read correction value is substituted into the work conversion matrix (S3). If the correction value has not been set, the correction value setting process is not performed (S
4). It is checked whether the operation command is a change command of the work effector (S5). If it is not a change instruction, the operation waits for an operation instruction again (S6). In the case of a change command, it is checked whether a correction value has been set for a new work effector (S7). If a correction value has been set, the corresponding correction value is read (S8). The read correction value is substituted into the work conversion matrix (S9). If the correction value has not been set, the process of setting the correction value is not performed (S10). After the processing, the process returns to check whether the operation command is a change command of the work effector (Sl
l).

In steps 1 and 7, a table is searched using the name of the work effector as a key in the area where the correction value for the work effector is stored. If the corresponding name is in the table, a correction value is set, and if there is no name, it is determined that there is no correction value.

In steps 3 and 9, the read correction value is set as the link length of the virtual joint set between the robot tip of the work conversion matrix and the work effector based on the description of the first embodiment. I do. When it is determined that there is no correction value, 0 is set as the correction value.

FIG. 5 is a flowchart of a robot mechanism calibration method according to the second embodiment of the present invention. 5 shows a method for calibrating a robot mechanism using a work effector and storing the obtained correction value. Hereinafter, the numerical value following S indicates a step number.

First, a mechanism correction value is calculated from the robot angle data and the tip position data by the conventional robot mechanism calibration calculation method (S21). Among the obtained correction values, the correction values set from the work effect device origin to the calibration point are read (S22). The name of the connected work effector is read from the robot mechanism parameters (S2
3). The table in which the work effector correction values are stored is checked to determine whether the name of the work effector exists (S2).
4). If not, the correction value of the work effector and the name of the work effector are associated and newly stored (S2).
5). If it exists, the existing correction value is overwritten (S26). Correction values other than the work effector portion are stored as robot mechanism correction values (S2).
7).

[0051]

According to the robot mechanism calibration calculation method according to the first aspect of the present invention, the mechanism calibration value obtained for the calibration target point is calculated based on the mechanism calibration value of the calibration target point viewed from the work effector mounting surface. And the calibration is performed using the coordinate transformation matrix, so that the robot mechanism correction value obtained for the calibration target point set on the work effector or the like can be treated as a correction value for the work effector. For this reason,
Since the correction effect can be reflected on the entire work effect device, the calibration work time can be reduced.

According to the second aspect, it is possible to record a plurality of mechanism calibration values of the work effector mounting surface for one robot, and when the work effector is changed, the mechanism corresponding to each work effector is changed. Since the calibration values are available,
Even when work is performed while replacing a plurality of work effect devices, a correction value can be set for each work effect device, and an optimum correction value can be given to each of the work effect devices. As a result, the accuracy can be improved, and the work efficiency can be improved.

According to the robot mechanism calibration calculation system according to the third aspect of the present invention, the correction value relating to the calibration point on the work effector attached to the end of the robot among the robot calibration correction values obtained by the calculation device. , The work effector correction value storage means for storing in association with the name of the work effector, and the mechanism calibration value obtained for the calibration target point is recorded as the mechanism effector's mechanism calibration value. A robot mechanism correction value obtained for a calibration target point set on a container or the like can be treated as a correction value for a work effect device. For this reason, the correction effect can be reflected on the entire work effect device as in the first aspect, and the calibration work time can be shortened.

According to a fourth aspect of the present invention, there is provided a work effector selecting means for selecting a calibration correction value corresponding to the name of a work effector from data stored in the work effector correction value storage means. A plurality of effector mechanism calibration values can be recorded for one robot, and when a work effector is changed, a mechanism calibration value corresponding to each work effector can be used. Even when work is performed while exchanging work effect devices, a correction value can be set for each work effect device, and an optimum correction value can be given to each. As a result, the accuracy can be improved as in the case of the second aspect, so that the work efficiency can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram showing a robot mechanism calibration calculation system according to a first embodiment of the present invention.

FIG. 2 is a schematic block diagram showing a robot mechanism calibration calculation system according to a second embodiment of the present invention.

FIG. 3 is a configuration diagram of a work effector correction value storage means of a robot mechanism calibration calculation system according to a second embodiment of the present invention;

FIG. 4 is a flowchart for performing a calculation using a work effect device calibration correction value according to the second embodiment of the present invention.

FIG. 5 is a flowchart for storing a mechanism calibration value according to the second embodiment of the present invention.

FIG. 6 is a schematic block diagram showing a conventional robot mechanism calibration calculation system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Robot operation program storage means 2 Processing device 3 Robot information input means 4 Robot operation control means 5 Robot operation output means 6 Robot teaching input means 7 Robot mechanism parameter storage means 8 Robot calibration data storage means 9 Program storage means 10 Work effector correction Value storage means 11 Work effect device correction value selection means

Claims (4)

[Claims] 1. A robot mechanism calibration calculation method for calibrating mechanism parameters of a robot joint angle, an origin, and a link length for determining a relationship between robot joint angle information and robot tip coordinate information, wherein a calibration target point is determined. A robot mechanism calibration calculation method characterized in that a mechanism calibration value obtained for the robot mechanism is recorded as a mechanism calibration value of a calibration target point viewed from a work effector attachment surface attached to the tip of the robot, and calibration is performed using a coordinate conversion matrix. . 2. The mechanism calibration value of the work effector mounting surface is set to 1
2. The robot mechanism calibration calculation method according to claim 1, wherein a plurality of recordings can be made for one robot, and when the work effector is changed, a mechanism calibration value corresponding to each work effector can be used. 3. A robot operation program storage means for storing an operation program of a work performed by the robot, an arithmetic unit for performing various operations for operating the robot, and a robot for storing design values for parameters relating to a robot mechanism required for the robot operation. Mechanism parameter storage means, and robot calibration data storage means for storing a calibrated correction value of a parameter relating to the robot mechanism which is an actual value, wherein the relationship between the joint angle information of the robot and the tip coordinate information of the robot is determined. A robot mechanism calibration operation system for calibrating a mechanism parameter from a robot mechanism parameter storage unit by the arithmetic unit and storing the same in the robot calibration data storage unit, wherein the robot calibration correction value of the robot calibration correction value obtained by the arithmetic unit is Calibration point on work effector mounted on tip And a work effector correction value storage unit for storing the correction value related to the name of the work effector, and recording the mechanism calibration value obtained for the calibration target point as the mechanism calibration value of the work effector. Characteristic robot mechanism calibration calculation system. 4. A work effect device selecting means for selecting a calibration correction value corresponding to the name of a work effect device from data stored in the work effect device correction value storage device, and 4. The robot mechanism according to claim 3, wherein a plurality of mechanism calibration values can be recorded for one robot, and when a work effector is changed, a mechanism calibration value corresponding to each work effector can be used. Calibration calculation system.