JP2001018182A - Robot mechanism calibration arithmetic method and system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress generation of dispersion by calculating a position deviation, generated by changing an attitude, by inputting difference information between a robot tip end position in a basic attitude and a robot tip end position in a changed attitude. SOLUTION: A target coordinate value set to a robot controller is changed without moving a robot so that it indicates a jig 22 for a support target even in a condition changing an attitude. By indicating the jig 22 for a support target by a robot tip end position 21' in a changed attitude, a difference between P0=(X0, Y0, Z0) which is a robot relatively measured position 24 first measured and P1=(X1, Y1, Z1) which is a robot relatively measured position 24' measured by changing an attitude is calculated as P1-P0=(X1-X0, Y1-Y0, Z1-Z0). Here, P1-P0 expresses a position deviation 25 from a target position of an actual robot tip end in the case of changing the attitude.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and system for calibrating a robot for accurately controlling the position of a robot tip by calibrating mechanical elements of an industrial robot performing various operations. Related to the technology to collect the necessary data.

[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 tip of the robot 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 calibration calculation method for correcting a mechanism error of the robot has been developed. In this method, an error in assembling or processing a robot is obtained by measurement, design values are corrected, and a calculation model is brought closer to an actual robot.

One of such calibration methods uses data obtained when the same position is designated by changing the posture of the robot. When the same point is designated by changing the posture of the robot, if the robot is accurate, the coordinate data of the robot calculated for that point should have the same value in any posture. However, if there is an error in the robot mechanism element, the calculated robot coordinate data differs even though the same point is indicated. By adjusting the angle origin and the link length so as to eliminate this difference, the error of the robot can be calibrated.

FIG. 7 shows an example of a block diagram of a conventional robot mechanism calibration calculation system. That is, this robot mechanism calibration calculation system is generally configured in a robot controller, and as shown in FIG. 7, a robot operation program storage means 1, a calculation device 2, a robot information input means 3, a robot operation control It comprises a means 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, and a program storage means 9.

More specifically, the robot operation program storage means 1 is a means for storing an operation program of a work performed by the robot, and includes an operation program for instructing a movement of the robot necessary for performing a calibration operation. It is stored here. The calculating means 2 is a part for performing various calculations necessary for operating the robot, such as creating a position command.
The calibration operation 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.
The necessary servo control is performed based on the encoder pulse data from the CPU and the operation instruction command from the arithmetic unit 2. 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 an operation instruction from the operator to the robot, and performs, for example, input monitoring from a teaching pendant. The robot mechanism parameter storage means 7 is a part for storing design values for parameters related to the robot mechanism required for the robot operation,
It is used for conversion from joint angle to robot tip position and back 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.

Using such a system, an operator operates a robot using a teaching pendant.
The robot is visually operated so as to point to the same point in different postures. Then, an operation program that specifies the same point in a plurality of postures is created. The calibration calculation of the robot mechanism is performed using the condition that the joint angle data of the robot recorded in the created operation program (or the tip position data calculated by the design value) and the robot tip position are the same.

[0008]

As described in the prior art described above, in order to perform a calibration operation of a robot mechanism, it is necessary for an operator to operate the position of the robot so as to coincide with the same position. However, matching the robot tip position in three dimensions using an input device such as a teaching pendant is very time-consuming and requires many man-hours. In addition, since the accuracy of alignment depends on the operator,
This also causes a variation in calibration results depending on the operator.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a method for simply and suppressing the occurrence of variation in data measurement required for performing a robot mechanism calibration operation. Another object is to provide a robot mechanism calibration system capable of properly performing the above method.

[0010]

According to a first aspect of the present invention, there is provided a robot mechanism calibration calculation method, wherein a joint angle origin and a link of a robot necessary for determining a relationship between robot joint angle information and robot tip coordinate position information. In a method of calibrating a mechanism parameter such as a length, a robot mechanism calibration calculation method of calculating using joint angle information when the same position is indicated, particularly while changing the tip posture of the robot,
The position shift caused by changing the posture was calculated by inputting the difference information between the robot tip position in the basic posture and the robot tip position in the changed posture, and the same position was designated from now on. It is characterized in that the same information is obtained.

According to the robot mechanism calibration calculation method of the first aspect, in the data measurement required for performing the robot mechanism calibration work, the position shift caused by changing the posture is corrected by the robot tip in the basic posture. Since it is possible to input from the difference information between the position and the robot tip position in the changed posture, it is simple and the occurrence of variation can be suppressed, so that the working time is shortened and the reliability is reduced. An improvement can be realized.

According to a second aspect of the present invention, there is provided a robot mechanism calibration calculation system for calibrating mechanism parameters such as a robot joint angle origin and a link length necessary for determining a relationship between robot joint angle information and robot tip coordinate position information. While changing the robot's tip posture,
A robot mechanism calibration calculation system that calculates using the joint angle information when the same position is specified, and when the position is shifted by changing the posture, the robot tip position in the basic posture and the change And a device for calculating robot joint angle data when the same position is specified from the input difference information. .

According to the robot mechanism calibration calculation system according to the second aspect, it is possible to obtain the same information as indicating the same position by changing the posture of the tip of the robot. Since it can be performed, the same effect as the above-mentioned claim 1 is obtained.
The robot mechanism calibration calculation method described above can be accurately performed.

According to a third aspect of the present invention, there is provided a robot mechanism calibration operation system according to the second aspect, wherein the robot is used to indicate a position, and has at least two rotational degrees of freedom in different directions to change the robot posture. Even in such a case, the apparatus has a device capable of always keeping the pointing direction at the tip in a fixed direction.

According to the robot mechanism calibration calculation system according to the third aspect, when the robot posture is changed, when the robot front position in the basic posture and the robot front position in the changed posture are indicated. , Two in different directions
By having two degrees of freedom, even if the posture of the robot is changed, the pointing direction is always kept in a fixed direction, and a device that enables the pointing of only the difference in position is provided. It is possible to easily input data in the system, to reduce the number of measurement steps and to reduce measurement errors.

[0016]

Embodiments of the present invention will be described below.

(Embodiment 1) FIG. 1 is a flowchart of a robot mechanism calibration calculation method for carrying out a first embodiment of the present invention. Hereinafter, the numerical value following S indicates a step number.

First, the operator defines a reference point at an arbitrary place (position) (S1). Next, the reference point is indicated by the robot tip position in a certain reference posture (S2). The three-dimensional coordinate data of the robot tip is read and stored by the measuring device (S3). Next, a robot operation is performed in which only the posture of the robot is changed without changing the coordinates (S4). Read the 3D coordinate data of the robot tip position in the changed posture (S
Five). The difference between the coordinate data in S3 and the coordinate data in S5 is calculated (S6). The obtained difference data is added to the coordinate value of the tip reference point, and the coordinate value when the tip reference point is designated in a changed posture is calculated (S7). This coordinate value and the changed posture are stored as tip position instruction data (S8). It is determined whether the posture change has been performed the required number of times (S9). If the number is not enough, the process returns to S4 and repeats the operation (S10). If the number is sufficient, execute the robot calibration calculation (S1
1).

In step 6, as shown in FIG. 2, the robot end position indicating jig for indicating the robot end position is used according to the robot reference posture, and the pointing target jig 22 is used.
Instruct. The tip of the pointing target jig 22 at this time is read as the display coordinate value T0 = (XA0, YA0, ZA0) on the robot controller. At this time, the position of the robot tip is measured by a three-dimensional measuring device provided separately. Let the robot relative measurement position 24 of the robot tip position 21 measured from the coordinate system 23 of this three-dimensional measuring device be P0 = (X0, Y0, Z0).
Here, P0 is a value expressing a relative position from the coordinate system 23 set by the measuring device, and is not a value in the robot coordinate system (a value expressed as a robot tip position).

Next, the robot is instructed to move to the same coordinate value T0 = (XA0, YA0, ZA0) in a posture different from the reference posture. If the robot has a mechanism error, a deviation occurs in the position actually specified even if the same coordinate value is specified. Therefore,
The robot tip position is separately provided again with the changed posture. 3
Measure with a dimension measuring device. The relative robot measurement position 24 'in the coordinate system 23 of the robot tip position 21' measured at this time is defined as P1 = (X1, Y1, Z1). This P1 is a value expressing the relative position of the measuring device from the coordinate system 23, similarly to P0.

In step 7, the target coordinate value set in the robot controller is changed instead of moving the robot so that the robot points at the pointing target jig 22 even when the posture is changed. As shown in FIG. 3, since the robot tip position 21 'indicates the pointing target jig 22 in the changed posture, P0 = (X0, Y0, Z0) which is the previously measured robot relative measurement position 24. And P, which is the robot relative measurement position 24 'measured while changing the posture.
The difference from 1 = (X1, Y1, Z1) is calculated as P1-P0 = (X1-X0, Y1-Y0, Z
1-Z0). Here, P1-P0 is the displacement 2 of the actual robot tip from the target position when the posture is changed.
Express 5 Therefore, in order to make the robot tip position 21 'coincide with the pointing target jig 22 in the state where the posture is changed, and to make the robot tip position 21 ", the pointing coordinate T1 is changed from the set coordinate value T0 to the robot in the reference posture. , The actual shift of the robot is shifted in the opposite direction by P1-P0, and T1 = T0-(P1-P0) = (XA0-X1 + X0, YA0-Y1 + Y0, ZA0-Z1 + Z0) .

If this coordinate value T1 is indicated to the robot in the changed posture, the positional deviation is corrected, and the robot tip position 21 "coincides with the pointing target jig 22.

If necessary, the corrected result is confirmed, and the same operation is repeated using the corrected result, thereby ensuring the accuracy required for the calibration calculation.

In the above description, the pointing target jig 22
May actually be virtual. That is,
It is assumed that the robot has been instructed to the pointing target jig 22 at an arbitrary position in the space, and the display coordinate value T0 in that state is assumed.
= (XA0, YA0, ZA0), and the subsequent operation is executed, whereby the processing can be realized.

(Embodiment 2) FIG. 4 shows a robot mechanism calibration calculation system for carrying out a 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. 4, a robot operation program storage means 1, a calculation device 2, a robot information input means 3, a robot Operation control means 4, robot operation output means 5,
The robot teaching input means 6, the robot mechanism parameter storage means 7, the robot calibration data storage means 8, the program storage means 9, the position displacement input means 10, the robot displacement storage means 11, and the robot position storage means 12 Have.

The reference numerals 1 to 9 are the same as in the conventional example, and the description is omitted.

The position displacement input means 10 is a part for inputting three-dimensional information of the robot tip position. It is a device that inputs numerical values by a key input or the like by an operator, or an interface device that inputs an output from a measuring instrument. The robot displacement storage means 11 is a device for temporarily storing the robot tip relative position input by the position displacement input means 10. The robot position storage unit 12 is a device for storing the designated coordinates of the robot tip in a state where the posture calculated by the calculation device 2 is changed, and providing the coordinates for calibration.

In the arithmetic unit 2, in addition to the function of the conventional calibration calculation, coordinate data for designating a reference point by the robot stored in the robot operation program storage means 1 and a posture input by the position displacement input means 10 Using the three-dimensional information of the robot tip position in the state in which the robot position has been changed and the three-dimensional information of the robot tip position in the reference posture stored in the robot position storage means 12, the robot tip position is determined based on the changed posture. Calculation of designated coordinates for matching the position is performed.

As the measurement data for the calibration calculation, not only the robot operation program stored in the conventional robot operation program storage means 1 but also the robot tip position data stored in the robot position storage means 12 is used.

This makes it possible to collect information necessary for robot calibration without performing positioning of the robot tip.

(Embodiment 3) A third embodiment of the present invention will be described with reference to FIGS. That is, this robot mechanism calibration calculation system has a robot tip position indicating means 13 in addition to the second embodiment.

The robot tip position indicating means 13 always keeps a constant posture even when the posture of the robot is changed.
This is a means for generating only the displacement of the position, and for example, as shown in FIG. 6, is configured to include a connecting portion 30 such as a universal joint having at least two rotational degrees of freedom.
When the robot is mounted on the robot at the robot mounting unit 31 which is one end, even if the posture of the robot mounting unit 31 changes with the robot mounting unit 31 'due to the change of the robot posture, the measurement position indicating unit which is the other end and is ahead of the joint. 32 always faces the direction of gravity 33 due to gravity.

Thus, when measuring the position of the robot tip, which is input data to the position displacement input means 10, it is possible to generate a portion that always maintains a common posture regardless of the posture of the robot tip. It is possible to easily measure the orientation of the position at the point.

[0035]

According to the robot mechanism calibration calculation method according to the first aspect, in the data measurement necessary for performing the robot mechanism calibration work, the displacement caused by changing the posture is corrected by the basic posture. Since it is possible to input from the difference information between the robot tip position and the robot tip position in the changed posture, it is simple and the occurrence of variation can be suppressed. It is possible to realize improvement of the performance.

According to the robot mechanism calibration calculation system of the second aspect, it is possible to obtain the same information as indicating the same position by changing the posture of the tip of the robot. Since it can be performed, the same effect as the above-mentioned claim 1 is obtained.
The robot mechanism calibration calculation method described above can be accurately performed.

According to the robot mechanism calibration calculation system of the third aspect, when the robot posture is changed, when the robot front position in the basic posture and the robot front position in the changed posture are indicated. , Two in different directions
By having two degrees of freedom, even if the posture of the robot is changed, the pointing direction is always kept in a fixed direction, and a device that enables the pointing of only the difference in position is provided. It is possible to easily input data in the system, to reduce the number of measurement steps and to reduce measurement errors.

[Brief description of the drawings]

FIG. 1 is a flowchart for carrying out a robot mechanism calibration calculation method according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a relationship between a relative position of a leading end portion when a robot posture is changed when the robot mechanism calibration calculation method according to the first embodiment is performed.

FIG. 3 is a diagram illustrating a correction calculation of a robot tip position coordinate when the robot mechanism calibration calculation method according to the first embodiment is performed.

FIG. 4 is a schematic block diagram showing a robot mechanism calibration calculation system according to a second embodiment.

FIG. 5 is a schematic block diagram illustrating a robot mechanism calibration calculation system according to a third embodiment.

FIG. 6 is a diagram illustrating an example of a tip pointing device for realizing a robot mechanism calibration calculation system according to a third embodiment.

FIG. 7 is a schematic block diagram showing a conventional robot mechanism calibration calculation system.

[Explanation of symbols]

 Reference Signs List 1 robot operation program storage means 2 arithmetic unit 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 position displacement input device Means 11 Robot displacement storage means 12 Robot position storage means 13 Robot tip position indicating means 21 Robot tip position of robot tip position indicating jig 22 Pointing target jig 23 Coordinate system of three-dimensional position measuring device 24 Robot relative measurement position 30 Connecting part 31 Robot mounting part 32 Measurement position indicating part 33 Direction of gravity

Claims (3)

[Claims] 1. A method for calibrating a mechanism parameter such as a robot joint angle origin and a link length necessary for determining a relationship between robot joint angle information and robot tip coordinate position information, particularly a robot tip posture. A robot mechanism calibration calculation method that calculates using the joint angle information when the same position is indicated while changing the position of the robot. And a difference between the robot posture and the robot posture in the changed posture is calculated, and the same information as when the same position is designated is obtained from the calculation. 2. A system for calibrating mechanism parameters such as a robot joint angle origin and a link length necessary for determining a relationship between robot joint angle information and robot tip coordinate position information. This is a robot mechanism calibration calculation system that calculates using the joint angle information when the same position is indicated while changing the position. When the position is shifted by changing the posture, the robot tip in the basic posture A device for inputting difference information between the position and the robot tip position in the changed posture, and a device for calculating robot joint angle data when the same position is designated from the input difference information. Robot operation calculation system. 3. A device for indicating a position by a robot,
3. The robot mechanism calibration according to claim 2, further comprising a device having at least two rotational degrees of freedom in different directions so that the pointing direction at the tip can always be kept constant even when the robot posture is changed. Arithmetic system.