JPH07328964A - Correcting method for off-line teaching data - Google Patents

Abstract

PURPOSE:To easily prepare the teaching data having high reproducibility of the position and attitude of an actual robot even if the linearity of a potentiometer is changed due to a secular change. CONSTITUTION:The relations between the actual displacement quantities, e.g. rotation angles, of elements such as the arms 61 and joints 62 of an actual robot 14 or tools 63 and the detected outputs of a potentiometer 64 are measured by a measuring means 67 in advance. The off-line teaching data are corrected based on the measured results, and the corrected off-line teaching data are set as the teaching data of the robot 14.

Description

Detailed Description of the Invention

[0001]

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

[0002]

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

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

When the teaching data to be given to the robot is created by using the offline teaching device, the operator sets the arrival target point of the tool while operating the robot on the image, and the tool can reach the target point. Then, the moving route reaching the target point is confirmed, and the confirmed moving route is stored in the storage means of the offline teaching device as offline teaching data.

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

Before the robot actually sets the teaching data, the operator operates the robot by the downloaded teaching data, and if necessary, finely adjusts the teaching data, The modified teaching data is set in the robot controller.

[0007]

By the way, the elements such as arms, joints, tools, etc. which compose the robot are operated by driving members such as motors and cylinders, and the displacement amount of each element due to the operation is It is detected as an electric signal by a detector such as a potentiometer, an inclinometer, or a linear resolver arranged in 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 based on this, servo control for the driving member,
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 memorizes or moves the robot posture based on the pulse number. Take control.

In this case, the displacement amount such as the rotation angle of the detector such as the potentiometer and the output electric signal (in the case of the potentiometer, it is often a voltage signal) are within the range of the specification accuracy of those detectors. It has a linearity with a certain accuracy, and this linearity with a certain accuracy is stored as the specification data of the detector in the offline teaching device. Therefore, the offline teaching data created by the offline teaching device with the zero position adjustment error of the detector (a fixed value that is actually measured, so-called offset) added is downloaded to the storage means of the robot controller. It will activate the robot. The offset may be added by either the offline teaching device or the robot controller.

By the way, the actual robots arranged at the production site and the like are mixed with old ones and new ones. In particular, the detector of the robot used for a long time is
Some linearity is out of the specification accuracy due to aging, etc., and the fact is that such a detector with poor linearity is also used.

However, when the offline teaching data created by the conventional offline teaching device is directly downloaded to the robot controller which controls the operation of the robot in which the detector such as the potentiometer whose linearity is changed is used. However, as a result, there was a problem that a large displacement of the tool occurred and it took a lot of time to correct the teaching data on site.

In the off-line teaching device, the teaching data obtained by teaching the actual robot may be uploaded from the robot controller to the storage means of the off-line teaching device to improve the efficiency of the teaching work. However, it is not possible to accurately reproduce the position / orientation of the robot on the screen of the graphic display due to changes in the linearity of the detector over time. Therefore, it is necessary to accurately verify (evaluate) the robot. There was also a problem that it could not be done.

The present invention has been made in view of the above problems, and easily creates teaching data with good reproducibility of the position / orientation of the actual robot even if the linearity of the detector changes. Therefore, an object of the present invention is to provide an off-line teaching data correction method capable of significantly reducing the correction time of teaching data in an actual robot.

[0015]

SUMMARY OF THE INVENTION The present invention provides a method for correcting off-line teaching data of a robot having a detector arranged on an arm, a joint or a tool and detecting a displacement amount of each of these elements, in which the element is displaced. When
The relationship between the actual displacement amount and the detection output of the detector is measured, and the offline teaching data created by the offline teaching device is corrected based on the measurement result, and the corrected offline teaching data is corrected by the robot. The feature is that it is set as teaching data.

[0016]

According to the present invention, the arm of the actual robot,
The relationship between the actual displacement of each element of the joint or tool and the detection output of the detector is measured, the offline teaching data is corrected based on this measurement result, and this corrected offline teaching data is taught by the robot. It is set as data.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

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

FIG. 2 is a block diagram showing the configuration of an off-line teaching device in which the configuration of the control circuit is drawn in detail.

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

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

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

On the axis of the potentiometer 64, in other words, on the joint 62, a rotary encoder 65 as an actual displacement amount detecting means is coaxially fixed in a detachable state. Note that the gear train may be used instead of the coaxial transmission. 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 is accurately calibrated.

Therefore, the actual displacement amount according to the rotation angle of the axis of the potentiometer 64, in other words, the rotation angle of the joint 62 of the robot 14, is the rotary encoder 6.
5 and supplies it to a measuring circuit 66 whose configuration will be described in detail later. In addition, the potentiometer 64
Angle of the axis of (rotation angle of joint 62 of robot 14)
An electric signal, which is a detection output corresponding to, is also supplied from the potentiometer 64 to the measuring circuit 66. The rotary encoder 65 and the measuring circuit 66 form a measuring means 67. The output signal of the measuring means 67 (actually digital data) is connected to the control circuit 16 which controls the entire offline teaching apparatus 10.

The control circuit 16 is a display 18 such as a CRT which is a display means for displaying figures and characters including a three-dimensional image of the robot 14, and an 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 as a storage means for storing created offline teaching data and the like is inserted, a robot, a work, a building, etc. A hard disk drive (hereinafter, also referred to as HDD) 26 as a storage means for storing image data such as the above and created offline teaching data and the like, and a printer 30 as an output means are connected to each other. ing.

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

The A / D converter 72 is a potentiometer 6
The electrical signal (usually a voltage signal) supplied from 4 is converted into digital data and supplied to the PC 74.

The counter 73 is the rotary encoder 6
The number of pulses (data) corresponding to the displacement amount signal (angle signal in this case) is counted by counting the pulses supplied from the PC 7
Supply to 4.

The PC 74 converts the digital data supplied from the A / D converter 72 into corresponding pulse number data. It should be noted that such an action of the PC 74 can be performed on the control circuit 16 side by storing a program corresponding to this action in the ROM 38.

In general, 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 needed. Then I will explain.

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 actual measurement data.

In FIG. 3, the actual measurement data 91 drawn as 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 constant angle about a joint 62 by a teaching box or the like (not shown).
4 is data plotted by measuring the relationship between the output voltage of No. 4 and the rotational displacement of the axis of the potentiometer 64 by the rotary encoder 65 and the output voltage.

Further, the offline teaching data 92 drawn in the ideal state of a straight line is likewise fixed on the screen of the display 18 with the arm 61 on the tool 63 side by the joint 6 at a constant angle.
It is the offline teaching data that is generated in the offline teaching device 10 when rotated around 2. The offline teaching data 92 is data corresponding to, for example, the guaranteed specifications at the time of purchase of the potentiometer 64, and is a so-called design value. Therefore, in FIG. 3, the hatched area represents an error due to the non-linearity caused by the aging of the potentiometer 64 or the like.

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

In FIG. 4, the value of the voltage signal is 1 V and the number of pulses is 10
The actual measurement data 91a and the offline teaching data 92a when converted into 00 and converted are shown.

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 using measured data 91a
The correction process by the correction circuit 45 when uploading to the storage means 0, for example, the HDD 26 will be described.

As the correction processing by the correction circuit 45, there are considered two processings, so-called map processing, in other words, processing by a lookup table (reference table) and processing using an interpolation formula.

First, the map processing will be described.

Table 1 is a table for map processing, and this table is a table created uniquely from FIG. The table for this map processing is also stored in the HDD 26. It should be noted that this map processing table is updated at any time as necessary, such as when a discrepancy occurs between the movement of the robot on the image based on the offline teaching data 92a on the display 18 and the movement of the actual robot 14. To do so.

[0041]

[Table 1]

In Table 1, the ideal number of pulses indicates the number of pulses corresponding to the offline teaching data 92a at a ratio of 1: 1 and the actual measured pulse number means the number of pulses corresponding to the measured data 91a at a ratio of 1: 1. Shows.

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

On the other hand, when uploading the measured data 91a to the HDD 26 in the offline teaching apparatus 10, the measured pulse number data at point A = 1620 (pulses) and the ideal pulse number data at point B = 1200 (pulses).
It should be converted to and stored. This conversion work 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 offline teaching data 92a is expressed by the equation (1) when the displacement amount is x (°) and the pulse number (pieces) is z.

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

Measured data 91a at point C → (50
°, 1500 pulses) Measured data 91a at point D → (75 °, 1800 pulses) The linear equation connecting the coordinate point C and the coordinate point D is given by the equation (2) when the pulse number is y and the displacement amount is x. The equation (3) is obtained by solving the equation (2) for the pulse number y.

(Y-1500) = (x-50) × (1800-1500) / (75-50) (2) y = 12 (x-50) +1500 (3) Then, when downloading. , Displacement of point B x =
The number of pulses at 60 ° = 1200 becomes x =
The number of pulses obtained by substituting 60, y = 162
It can be easily converted to 0.

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

As the interpolation formula, not only the above-described piecewise linear interpolation formula, but also a polynomial approximation formula, a spline interpolation formula, and a continuous fraction interpolation formula can be used.

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

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

FIG. 5 shows a functional block structure derived from the above-mentioned embodiment.

That is, in FIG. 5, the detector 101
The displacement of (for example, the potentiometer 64) is measured as the displacement amount, and the electric signal from the detector 101 is measured as the detection output by the measuring unit 102 (for example, the measuring unit 67).

The measurement result is stored in the storage means 103 (for example, RA
M40, HDD26).

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

Control means 104 (eg control circuit 16)
The interpolation formula / map processing table unit 105 (for example, the correction circuit 45) performs the interpolation formula calculation or the map processing table process, 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. Remembered.

The control means 104 fetches the interpolation type or map processing table from the storage means 103 at the same time as the off-line teaching data before correction. Corrected off-line teaching data is created by performing correction calculation processing based on the captured data, etc.
It is stored in the storage means 103.

The present invention is not limited to the above 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 amount of each element of the arm, joint or tool of the actual robot and the detection output of the detector for detecting this actual displacement amount are set in advance. Is measured in advance, 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. Therefore, even if the linearity of the detector changes, it is possible to easily create teaching data with good reproducibility of the position / orientation of the actual robot.
Moreover, the correction time during online teaching by the actual robot is significantly reduced.

Further, even for an actual robot whose performance such as linearity of the detector is deteriorated due to secular change or the like, the difference between the offline teaching data and the actual measurement data (online teaching data) is taken into consideration. It is easy to make correction (correction) and create (so-called upload) the offline teaching data based on the online teaching data. When uploading in this way, in the offline teaching device, the correct posture of the actual robot can be displayed on the screen. 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. Therefore, the effect of reducing the teaching correction work in the actual robot is also achieved. In this case, the work performed by the worker on the site is considerably reduced, so that a secondary effect of improving the overall work efficiency is also obtained.

[Brief description of 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.

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

FIG. 4 is a characteristic diagram showing an example of actual measurement data and offline teaching data regarding a relationship between a displacement amount and the number of detected pulses.

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

[Explanation of symbols]

10 ... Offline teaching apparatus 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 the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication location G05B 19/404 19/42 (72) Inventor Mitsugu Kaneko 1-10-1 Shin-Sayama, Sayama-shi, Saitama Inside Honda Engineering Co., Ltd.

Claims (2)

[Claims] 1. A method for correcting off-line teaching data of a robot having a detector arranged on an arm, a joint or a tool for detecting the amount of displacement of each of these elements, the actual displacement of the element when the element is displaced. The relationship between the quantity and the detection output of the detector is measured, the offline teaching data created by the offline teaching device is corrected based on the measurement result, and the corrected offline teaching data is set as the teaching data of the robot. An off-line teaching data correction method characterized by: 2. The off-line teaching data correction method according to claim 1, wherein the detector is a potentiometer, an inclinometer or a resolver, and the detection output is an electric signal.