JP3075667B2 - Offline teaching data correction method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for correcting off-line teaching data suitable for use in, for example, an off-line teaching device for a welding robot.

[0002]

2. Description of the Related Art Conventionally, robots are frequently used for the purpose of, for example, welding, and a method of creating teaching data (also referred to as teaching data) to be given to the robot by an offline teaching device has been widely used (for example, And JP-A-5-73122).

In this off-line teaching device, images of a robot, a work, and the like are displayed as a three-dimensional image on a screen of a graphic display, and the robot is operated on the three-dimensional image to form an arm,
Simulation of movement of joints and tools is performed.

When creating teaching data to be given to a robot using an offline teaching device, an operator sets an arrival target point of a tool while operating the robot on an image, and the tool can reach the target point. Is confirmed, and furthermore, the traveling route arriving at the target point is confirmed, and the confirmed traveling route is stored as offline teaching data in the storage means of the offline teaching device.

Further, the same operation is performed by setting the next target point, and offline teaching data for all target points is sequentially obtained. The offline teaching data obtained in this way is transferred to a storage means of a robot controller (hereinafter, also referred to as a robot controller), downloaded and set as teaching data of the robot.

[0006] Then, before performing the actual work by the robot in which the teaching data is set, the operator operates the robot using the downloaded teaching data, finely modifies the teaching data as necessary, and The modified teaching data is set in the robot controller.

[0007]

By the way, the elements such as arms, joints, and tools constituting the robot are actuated by driving members such as motors and cylinders, and the displacement of each element due to the actuation is determined by the amount of displacement. It is detected as an electric signal by a detector such as a potentiometer, an inclinometer, or a linear resolver disposed on each element (each driving member).

In practice, driving members such as motors and cylinders are controlled by servo control or sequence control in order to control positioning accuracy and speed accuracy with high accuracy.
The robot controller obtains an electric signal which is a detection output of the detector as a feedback signal or an operation confirmation signal, and performs servo control on the driving member based on the signal,
Perform sequence control.

In this case, the robot controller generally converts an electric signal proportional to the amount of displacement received from the detector into a pulse number by an A / D converter or the like, and stores or stores the posture of the robot based on the pulse number. Perform control.

In this case, the displacement amount such as the rotation angle of a detector such as a potentiometer and an output electric signal (in the case of a potentiometer, a voltage signal is often used) are within the specification accuracy of the detector. It has linearity with a constant accuracy, and the linearity with the constant accuracy is stored as specification data of a detector in the offline teaching device. Therefore, the offline teaching data obtained by adding the zero position adjustment error of the detector (fixed value actually measured, so-called offset) to the offline teaching data created by the offline teaching device is downloaded to the storage means of the robot controller. The robot will be activated. The addition of the offset may be performed by any of an offline teaching device and a robot controller.

[0011] By the way, old robots and new robots are mixed in a production site or the like. In particular, the detector of a long-used robot is:
In some cases, the linearity is out of the specification accuracy due to aging or the like, and in reality, such a detector having poor linearity is also used.

However, when offline teaching data created by a conventional offline teaching device is directly downloaded to a robot controller for controlling the operation of a robot using a detector such as a potentiometer having a changed linearity, However, as a result, there is a problem that a large displacement of the tool occurs and it takes much time to correct the teaching data on site.

In the offline teaching device, the teaching data obtained by teaching the actual robot may be uploaded from the robot controller to the storage means of the offline teaching device and used to improve the efficiency of the teaching operation. However, due to the aging of the linearity of the detector, etc., it becomes impossible to accurately reproduce the position / posture of the robot on the screen of the graphic display. Therefore, it is necessary to accurately verify (evaluate) the robot. There was also a problem that it became impossible.

The present invention has been made in view of such a problem, and easily creates teaching data with good reproducibility of the position and orientation of an actual robot even if the linearity of the detector changes. Accordingly, it is an object of the present invention to provide a method for correcting offline teaching data, which can significantly reduce the time required for correcting teaching data in an actual robot.

[0015]

The present invention is arranged on an arm, a joint, or a tool, and detects the displacement of each of these elements .
Linearity of detector for outputting a detection output corresponding to the displacement amount
The actual robot but with the detector, which was outside the specified accuracy
When correcting the off-line teaching data relating, before
Pre-calibrated to detect the actual displacement of the
A displacement amount detecting means detachably secured to said elements, when displacing the said element, a plurality of said detection output of said detector and the actual displacement amount of the element detected by the displacement detecting means measuring the correspondence between a point, the off-line teaching data created by the offline teaching apparatus, so as to correspond to the actual displacement amount of the element based on the corresponding relationship at a plurality of points of measurement as the map
Corrected by up processing table processing or interpolation equation calculation, and sets the corrected off-line teaching data as teaching data of the actual b <br/> bot.

[0016]

According to the present invention, the arm of the actual robot,
Measure the relationship between the actual displacement of each element of the joint or tool and the detection output of the detector, correct the offline teaching data based on the measurement result, and use the corrected offline teaching data for robot teaching. Set as data.

[0017]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an overall configuration including an offline teaching device.

FIG. 2 is a block diagram showing the configuration of the off-line teaching device which details the configuration of the control circuit.

In FIG. 1, a robot controller 12 as a robot control device is connected to, for example, a welding robot 14 (hereinafter, simply referred to as a robot 14) which is an actual robot, and controls the robot.

The robot 14 has an arm 61, a joint 62, and a tool 63.
Although a detector such as a potentiometer, an inclinometer, or a resolver is provided, in this embodiment, a method of correcting offline teaching data relating to the potentiometer 64 attached to the joint 62 will be described in order to avoid complexity. I do. Inclinometer,
As a method of correcting the offline teaching data related to the resolver, the method of correcting the offline teaching data related to the potentiometer 64 described below can be similarly applied.

The potentiometer 64 is a variable resistor having sliding contacts, as is well known, and is a detector that outputs an electric signal (voltage signal, current signal or resistance signal) corresponding to the rotation of the shaft. . The inclinometer is a detector that includes a photosensor, a pendulum, a torque motor, and the like, and outputs a voltage signal proportional to the sine of the inclination angle. Further, a resolver, for example, a linear resolver is a detector having a semiconductor magnetoresistive element and outputting sine and cosine signals whose amplitude changes according to linear displacement. At the time of purchase, these detectors have linearity and resolution specified in the specification.

A rotary encoder 65 as an actual displacement amount detecting means is coaxially fixed to a shaft of the potentiometer 64, in other words, a joint 62 in a detachable state. In addition, it may be via a gear train instead of coaxial. It is assumed that the relationship between the rotation angle of the rotary encoder 65 and the number of output pulses is known in advance and has been accurately calibrated.

Therefore, the actual displacement amount corresponding to the rotation angle of the shaft of the potentiometer 64, in other words, the rotation angle of the joint 62 of the robot 14, is determined by the rotary encoder 6
5 and supplied to a measurement circuit 66 whose configuration will be described in detail later. Also, potentiometer 64
Angle of rotation (rotation angle of joint 62 of robot 14)
Is also supplied from the potentiometer 64 to the measuring circuit 66. The rotary encoder 65 and the measuring circuit 66 constitute a measuring means 67. An output signal (actually, digital data) of the measuring means 67 is connected to a control circuit 16 for controlling the entire offline teaching device 10.

The control circuit 16 is a display 18 such as a CRT for displaying figures and characters including a three-dimensional image of the robot 14 and input means for giving characters, commands and various instructions. A keyboard 20, a mouse 22, a floppy disk drive (hereinafter, also referred to as FDD) 24 into which a floppy disk is inserted as storage means for storing the created offline teaching data, and the like, robots, works, buildings, and the like. A hard disk drive (hereinafter, also referred to as HDD) 26 having a built-in hard disk as storage means for storing image data such as image data and created offline teaching data and the like, and a printer 30 as output means are connected respectively. ing.

As shown in FIG. 2, the control circuit 16 is an interface (hereinafter, also referred to as an I / F) which is an interface circuit between a central control unit (CPU) 32 as control means and a keyboard 20 and a mouse 22. 36, a ROM 38 storing a control program, and a work RA
M40, joint 62, arm 61, tool 63 of robot 14
The simulation control circuit 44 controls the simulation of the movable part, the drawing control circuit 46 controls the drawing on the screen of the display 18, the data creation circuit 47 creates the offline teaching data, and corrects the offline teaching data. A correction circuit 45, an I / F 48 for the display 18, and the printer 30;
I / F for FDD 24, HDD 26, and measuring means 67
50. The measuring means 67 includes, in addition to the rotary encoder 65, an A / D converter 72, a counter 73, and a personal computer (hereinafter, also referred to as PC) 74, which constitute the measuring circuit 66 shown in FIG.

The A / D converter 72 includes a potentiometer 6
4 is converted into digital data and supplied to the PC 74.

The counter 73 is a rotary encoder 6
The number of pulses (data) corresponding to the displacement signal (in this case, the angle signal) is counted by the PC
4

The PC 74 converts digital data supplied from the A / D converter 72 into corresponding pulse number data. The operation of the PC 74 may be performed by the control circuit 16 by storing a program corresponding to the operation in the ROM 38.

Generally, the output data of the A / D converter 72 is managed as pulse number data. Therefore, in the following description, the A / D converter 72 converts an electric signal into pulse number data as necessary. Then it will be explained.

Next, the operation of the above embodiment will be described in detail.

FIG. 3 is a diagram showing an example of the correspondence between the offline teaching data and the actually measured data.

In FIG. 3, measured data 91 drawn by a curve
Is a potentiometer 6 when the arm 61 of the robot 14, for example, on the tool 63 side is rotated by a fixed angle around the joint 62 by a teaching box (not shown) or the like.
4 shows data obtained by measuring and plotting the relationship between the output voltage and the output voltage when the rotary displacement of the shaft of the potentiometer 64 is detected by the rotary encoder 65.

The off-line teaching data 92 drawn in the ideal state of the straight line is similarly obtained by moving the arm 61 on the tool 63 side by a predetermined angle on the screen of the display 18 to the joint 6.
2 is offline teaching data generated in the offline teaching device 10 when rotated about the center 2. The offline teaching data 92 is data corresponding to, for example, guaranteed specifications of the potentiometer 64 at the time of purchase, and is a so-called design value. Therefore, in FIG. 3, an area indicated by hatching indicates an error due to non-linearity caused by aging of the potentiometer 64 or the like.

In practice, the voltage signal obtained from the potentiometer 64 is converted into the number of pulses by the A / D converter 72 and the PC 74, and the off-line teaching data 92 is also created as the number of pulses.

FIG. 4 shows that the value of the voltage signal 1V is
9 shows actual measurement data 91a and off-line teaching data 92a converted to 00.

Next, the correction processing by the correction circuit 45 when the offline teaching data 92a is downloaded to the storage means of the robot controller 12 based on the correspondence between the displacement amount and the pulse number obtained as shown in FIG. Off-line teaching device 1 for actual measurement data 91a
A correction process by the correction circuit 45 when uploading data to a storage unit, for example, the HDD 26 will be described.

As the correction processing by the correction circuit 45, there are two kinds of processing, that is, a so-called map processing, that is, a processing using a look-up table (reference table) and a processing using an interpolation formula.

First, the map processing will be described.

Table 1 is a table for map processing, and is a table uniquely created from FIG. The map processing table is also stored in the HDD 26. The map processing table is updated as needed, for example, when a mismatch occurs between the motion of the robot on the image based on the offline teaching data 92a on the display 18 and the motion of the actual robot 14. To do.

[0041]

[Table 1]

In Table 1, the ideal pulse number indicates the number of pulses corresponding to the offline teaching data 92a at a ratio of 1: 1. The actually measured pulse number indicates the number of pulses corresponding to the actually measured data 91a at a ratio of 1: 1. Is shown.

Therefore, the offline teaching data 9
The correction processing by the correction circuit 45 when downloading 2a to the storage means of the robot controller 12 will be described. In this case, the offline teaching data 92
For example, ideal pulse number data = 1200 (pulses) at point B with a displacement amount of 60 ° on a may be converted into actual pulse number data = 1620 (pulses) at point A on actual measurement data 91a. Since this conversion is automatically performed by the control circuit 16 and only needs to refer to the table, the offline teaching data 92a is corrected (corrected) very easily and in a short time, and is set as teaching data in the robot controller 12. can do.

On the other hand, when uploading the actually measured data 91a to the HDD 26 in the offline teaching device 10, the actually measured pulse number data at point A = 1620 (pulses) is replaced by the ideal pulse number data at point B = 1200 (pulses).
And store it. This conversion is also very easy because it is similar to the case of downloading.

Next, the processing by the correction circuit 45 using the interpolation formula will be described.

Here, a case where a piecewise linear equation is used as the interpolation equation will be described.

As can be seen from FIG. 4, the off-line teaching data 92a is represented by the following equation (1) when the displacement is x (°) and the number of pulses (number) is z.

Z = x × 20 (1) Similarly to the above-described map processing, for example, the displacement amount x = 60 °
Considering download and upload of points A and B, points C and D near displacement x = 60 °
It is assumed that the actual measurement data 91a is obtained as coordinates as follows.

The measured data 91a at point C → (50
(1,500 pulses) Actual measurement data 91a at point D → (75 °, 1800 pulses) A linear equation connecting coordinate points C and D is given by equation (2) where y is the number of pulses and x is the displacement. Equation (3) is obtained by solving Equation (2) for the number of pulses y.

(Y-1500) = (x−50) × (1800−1500) / (75−50) (2) y = 12 (x−50) +1500 (3) Therefore, when downloading, , The displacement x of the point B =
When the number of pulses at 60 ° = 1200, x =
Number of pulses y = 162 obtained by substituting 60
It can be easily converted to zero.

On the other hand, when uploading, if the pulse number y at the point A is y = 1620, a displacement amount x (x = 60) can be obtained from the equation (2). By substituting = 60 into equation (1), the pulse number z (z = 1200) at point B can be easily obtained.

The interpolation formula is not limited to the above-described piecewise linear interpolation formula, but may be a polynomial approximation formula, a spline interpolation formula, or a continued fraction interpolation formula.

As described above, according to the above-described embodiment, the linearity of the potentiometer 64 as a detector is deteriorated due to aging or the like from the performance characteristics (offline teaching data 92a) at the time of creating offline teaching data. When the rotary encoder 65 is mounted on the shaft of the potentiometer 64 or a member that rotates integrally with the shaft, the relationship between the electric signal from the potentiometer 64 and the displacement from the rotary encoder 65 is measured. By doing so, the effect that accurate conversion of the data between the offline teaching data 92a and the actual measurement data 91a can be performed easily and in a short time is achieved.

That is, an error between the offline teaching data 92a and the actual measurement data 91a obtained by the actual robot 14 can be easily absorbed, and the teaching data with good reproducibility of the position and orientation of the actual robot 14 can be easily created. it can.

FIG. 5 shows a functional block diagram derived from the above embodiment.

That is, in FIG.
The displacement of the (for example, potentiometer 64) is measured by the measuring means 102 (for example, the measuring means 67) as the displacement amount, and the electric signal from the detector 101 is detected as the detection output.

The measurement result is stored in the storage unit 103 (for example, RA
M40, HDD 26).

In the storage means 103, in addition to the memory address of the measurement result, an interpolation formula / map processing table and offline teaching data before correction (actual measurement data before correction) are stored.
And the memory address of the offline teaching data after correction is prepared.

Control means 104 (for example, control circuit 16)
The interpolation formula / map processing table unit 105 (for example, the correction circuit 45) performs interpolation formula calculation or map processing table processing, and the calculation result and the processing result are stored in the memory address of the interpolation formula / map processing table of the storage unit 103. It is memorized.

The control unit 104 fetches an interpolation formula or a map processing table from the storage unit 103 simultaneously with the offline teaching data before correction. The corrected offline teaching data is created by performing a correction calculation process based on the captured data and the like,
It is stored in the storage means 103.

The present invention is not limited to the above-described embodiment.
It goes without saying that various configurations can be adopted without departing from the gist of the present invention.

[0062]

As described above, according to the present invention, the actual displacement of each element of the arm, joint or tool of the actual robot and the detection output of the detector for detecting the actual displacement are determined in advance. Is measured, the offline teaching data is corrected based on the measurement result, and the corrected offline teaching data is set as the teaching data of the robot. For this reason, even if the linearity of the detector changes, it is possible to easily create teaching data with good reproducibility of the position and orientation of the actual robot.
In addition, the correction time during online teaching by the actual robot is greatly reduced.

In addition, the error between the offline teaching data and the actual measurement data (online teaching data) is also taken into account for an actual robot whose performance, such as linearity, of the detector has deteriorated due to aging or the like. It is also easy to create (so-called, upload) the correction (correction) of the offline teaching data based on the online teaching data. Can be reproduced, and manufacturing equipment can be accurately verified and evaluated.

Further, even when the detector is replaced, the existing teaching data set in the robot controller is corrected (corrected) only by measuring the relationship between the actual displacement amount of the detector and the detection output. ), The effect of reducing teaching correction work by the actual robot is also achieved. In this case, the on-site work of the worker is considerably reduced, so that a secondary effect that overall work efficiency is improved can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration including an offline teaching device to which an embodiment of the present invention is applied.

FIG. 2 is a block diagram showing a detailed configuration example of a control circuit and a measurement circuit in the example of FIG. 1;

FIG. 3 is a characteristic diagram showing an example of measured data and off-line teaching data on a relationship between a displacement amount and an output voltage of a detector.

FIG. 4 is a characteristic diagram showing an example of measured data and off-line teaching data on the relationship between the displacement amount and the number of detected pulses.

FIG. 5 is a functional block diagram according to the present invention.

[Explanation of symbols]

Reference Signs List 10 offline teaching device 12 robot controller 14 robot 16 control circuit 61 arm 62 joint 63 tool 65 rotary encoder 66 measuring circuit 67 measuring means

────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Mitsugu Kaneko 1-10-1 Shinsayama, Sayama-shi, Saitama Honda Engineering Co., Ltd. (56) References JP-A-3-75804 (JP, A) JP-A-5 -95692 (JP, A) JP-A-5-269684 (JP, A) JP-A-4-116411 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B25J 9/10 B25J 9/22 B25J 13/08 G05B 19/42

Claims (2)

(57) [Claims] 1. An arm, a joint or a tool, which detects an amount of displacement of each element and outputs a detection output corresponding to the amount of displacement.
When the linearity of the detector output by correcting the off-line teaching data according to the actual robot having detectors <br/> became out of specification accuracy, in order to detect the actual displacement amount of the element in advance Calibrated
A displacement amount detecting means is detachably fixed to the element, when displacing the said elements, and said detection output of said detector and the actual displacement amount of the element detected by the displacement detecting means and measures the corresponding relationship in the plurality of points, a plurality of points of the off-line teaching data prepared was measured as above by the offline teaching apparatus
And the actual displacement of the element based on the correspondence in
Map processing table processing or interpolation formula operation
More correcting method of correcting off-line teaching data and sets the corrected off-line teaching data as teaching data of the actual <br/> robot. 2. The method according to claim 1, wherein the detector is a potentiometer, an inclinometer, or a resolver, and the detection output is an electric signal.