JPS6095605A - Teaching data correcting method of robot - Google Patents

Abstract

PURPOSE:To reduce a maintenance cost by using a robot itself as a measuring instrument, deriving a coordinate matrix by measuring three reference points prescribed in advance, and correcting a teaching data. CONSTITUTION:A welding robot 1 of six-axes has a base 2, the first-the third rotating shafts, turning shafts 3-7, etc. and a welding gun 8 of its tip part, it is driven by each driving device, and also each shaft position is detected. A control device 9 has a robot controlling microcomputer and a correcting microcomputer of a teaching data, and the controlling microcomputer executes various functions in accordance with a correcting mode selected by a switch and a teaching mode, etc. According to this correcting method, an existing coordinate position data is derived by an operation quantity of every shaft in three reference points which are not on one straight line prescribed in advance. By said data and the coordinate position data corresponding to said reference point in an old orthogonal coordinate system of the teaching data, a coordinate converting matrix between both of them is derived, and by this matrix, said teaching data is corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a method for correcting teach data to a robot 1.

In order to deal with the increasing number of car models and repeated model changes due to the diversification of needs, the conventional technology-enabled car body assembly lines have introduced a wide range of general-purpose and quick-response Nihon Hots 1, especially in the welding process. are doing.

By the way, the robots 1, such as this one, placed on the assembly line.
-, maintenance (overball, etc.) is performed periodically, but each time this maintenance is performed, the robot installation position shifts, so it is necessary to change the teaching data stored in the storage device.

In this case, it is possible to re-create the teaching data by performing new teaching, but this would take a lot of time and reduce the line's operating rate, so normally the original teaching data is transferred to the robot 1. Corrections are being made according to the installation deviation.

Conventionally, when making such corrections, the installation deviation of the robot was actually measured using a special measuring instrument, and the
A coordinate transformation matrix is calculated based on the ll value, and the teach data is corrected using the coordinate transformation matrix.

However, such conventional methods require specialized measuring instruments, which not only increases costs, but also requires the preparation of multiple measuring instruments when maintaining multiple robots on an assembly line at once. If this is not done, work efficiency will deteriorate, and there is also the problem that the operating rate of the production line will decrease.

In addition, when using a dedicated measuring device, it is necessary to secure a working area for measurement around the robot installed on the line, but if such a working area cannot be secured, the teaching data cannot be corrected. There was also a serious problem that there was no such thing.

This invention has been made in view of the above-mentioned background, and it is an object of the present invention to provide a robot teach data correction method that does not require the use of a dedicated measuring instrument as described above.

Therefore, the teaching data correction method of Rohottsu 1- according to the present invention is such that the multi-axis robot used in the above-mentioned welding robot is equipped with an axis position detector called an internal field sensor on each of its axis muscles. Focusing on the fact that

In other words, when the working end of the multi-axis robot 1- as described above is positioned at three predetermined reference points that are not on a straight line in its operating area, the amount of movement of each axis muscle obtained from each axis position detector is based on.

After obtaining the coordinate position data of the three reference points in the new orthogonal coordinate system of the currently installed multi-axis robot,
Based on the three coordinate position data of the three reference points in the old orthogonal coordinate system in which the teaching data of multi-axis robots 1~ are defined, coordinate transformation 71-risk between the new and old orthogonal coordinate systems is performed. , the teaching data of the multi-axis robot 1- is corrected based on the coordinate transformation 71-rix.

Embodiments of the present invention will now be described with reference to the accompanying drawings.

FIG. 1 is an external view of a multi-axis robot showing an embodiment of the present invention, and FIG. 2 is a skeleton diagram for explaining the motor functions of the multi-axis robot shown in FIG. 1, represented by symbols.

In both figures, for example, a six-axis polar coordinate welding robot 1 installed at the origin O of a right-handed orthogonal coordinate system (omitj, k) defined at a predetermined position on a welding line (not shown) has a base 2 and a base 2. A two-shaft component 3 consisting of a first rotating shaft 3A that rotates in the O1 direction with respect to the first rotating shaft 3A and a first rotating shaft 3B that rotates in the 02 direction with respect to the first rotating shaft 3A; j2 with respect to the first pivot axis 3B. A telescoping shaft 4 that expands and contracts in the direction, a 24th rotation axis 5 that rotates in the 04 direction with respect to this telescoping shaft 4, and a 24th rotation axis 5 that rotates in the 04 direction with respect to this second rotation axis 5.
It consists of a second rotating shaft 6 that rotates in five directions, and a third rotating shaft 7 that rotates in the θG force direction with respect to the second rotating shaft 6. A welding gun 8 is attached.

The six axes from the two-axis component 3 to the third rotation axis 7 in this welding robot 1 are each driven by a drive device (not shown) for each axis, which is composed of a hydraulic actuator or an electric motor, and each movement amount is It is detected by a shaft position detector such as an AbFlu 1-encoder provided on each shaft muscle.

In addition, in FIG. 1, 9 is a control device of the welding robot 1, and 10 is a teaching box.

In addition, in FIG. 2, the lengths of the base 2 and the first rotating shaft 6A are respectively C": and CW (constant), and the combined length of the first rotating shaft 6B and the telescopic shaft 4 is L"3. (variable), the length between the second rotation axis 5 and the second rotation axis 6 to the bending position (90° bending position) is C (constant), and the remaining part of the second rotation axis 6 The combined length of the third rotating shaft 7 and the length of the welding gun 8 are each expressed as CjlG (constant).

Furthermore, the following θ1. θ:! +'3+ 04rO
Let r++ ('e (hereinafter abbreviated as ro, ~06)) represent the amount of operation (displacement variable) of each axis.

Figure 3 shows the welding robot 1-1 shown in Figures 1 and 2.
FIG. 2 is a block diagram of a control system of FIG.

In the control device 9 in the figure, 11 is a robot control microcomputer (hereinafter referred to as the "control microcomputer"), and 12 is a teach data correction microcomputer (hereinafter referred to as the "correction microcomputer"). It is.

The control microcomputer 11 is selected by, for example, a teach mode/playback mode selection switch and a correction mode changeover switch 16 provided on a robot control panel (not shown), and performs the following functions depending on the mode 14.

(a) When the chirch mode is selected and the correction mode selector switch 13 is off, when a drive command for each axis of the robot 1 is input from the teaching box 10 via the interface circuit 14, the control microcomputer 11 The first . An interface circuit 14.drive devices 15A, . D/
A converters 168 to 16F and drive circuits 17Δ to 17F
Each is controlled independently via the .

Therefore, each axis of the welding robot 1-1 moves according to the drive command, and the position and posture of the welding gun 8 are adjusted to 'If'! be done.

Therefore, by appropriately operating the teaching box 10, the instructor can position the welding gun 8 at the welding point position on the workpiece in a predetermined posture, and when the teacher turns on the memory switch of the teaching box 10 at the time of positioning, The control microcomputer 11 is the shaft position detector 1
．． Welding robots 1~ detected by 8A~18F
01゜02'r '3 r 04 +' O5r OG
is taken in through the interface circuit 14 and then stored in the teach data memory 20 through the interface circuit for one day.

Note that the motion amounts 01 to θ6 of each axis muscle from each axis position detector 18A to 18F are also used for positioning control during axis driving.

(b) When the teach mode is selected and the correction mode changeover switch 13 is on, it is almost the same as when the correction mode changeover switch 13 is off, except that the captured operation amounts 01 to θ6 are stored in the teach data memory 20. Interface circuit 1 without memorizing
The data is transferred to the correction microcomputer 12 after 4 or 1 day (described later).

(c) When the playback mode is selected, the control machine 1 operates the interface circuit 14 while referring to the teach data stored in the teach data memory 20. The drive devices 15A to ISF are controlled via the D/A converters 16A to 16F and the drive circuits 17A to 17F, thereby moving the welding gun 8 that is attached to the welding robot 1 in accordance with the teaching data.

At this time as well, the movement amounts 01 to 06 of each axis muscle from the axis position detectors 18A to 18F are used for positioning control during axis driving.

Next, the correction microcomputer 12 operates the first. The sampling switch 21 is activated when an installation error occurs during maintenance of the welding robot 1 shown in FIG. The correction switch 22 is a switch that is turned on when sampling the obtained movement amount of each axis.

This is a switch that is turned on when starting the correction calculation of the teach data after sampling is completed, and the operating state of both switches is the interface time! It is checked by the correction microcomputer 12 via 823.

The operation of this correction microcomputer 12 will be explained in detail below, including some operations of the control microcomputer 11, but it is assumed that maintenance has been performed on the welding robots 1 to 1 and their installation positions have shifted. do.

First, the teach mode/playback mode selection switch on the robot control panel (not shown) is operated to set the teach mode, and the correction seventh changeover switch 13 is turned on.

In this way, the control microcomputer 11 can perform the steps from 5TEP1, 2 to 5TEP of the processing program flow diagram shown in FIG.
Proceed to P3 and wait for a drive command from the teaching box 10.

Next, the instructor operates the teaching box 10,
1st. 1 for driving each axis from the first rotating shaft 6A to the third rotating shaft 7 in the welding robot 1-1 shown in FIG.
When a drive command is input to the control device S, the control microcomputer 1
1 proceeds to 5TEEP 4 and drives the drive device 15A to 151? based on the drive command. The drive control is performed.

When this 5TEP 4 drive control is performed, the welding robot 1 moves and picks up the welding gun 8 at its tip (J-digit welding gun 8 moves in a required direction).

Then, the n800 switch and end switch on the teaching box 10 must be turned on.

5TEP Since a loop of 3, 4, 5, 7.3 is formed, the instructor repeatedly operates the teaching pendant 10 to position the welding can 8 at the following three reference points Pa, Pb, and Pc. If you turn on the memory switch every time you position to each reference point P a , F', b, P c.

Each time the control microcomputer 11 is turned on, the control microcomputer 11 inputs the axis position detection fa18A~181'' or the motion amount 01~06 of each axis of the robot detected through the interface circuit 14 during positioning. Interface circuit 1
4 or is transferred to the correction microcomputer 12 via the IS.

Then, when the end switch is turned on at the time when the acquisition of the operation amounts regarding the three reference points Pa, Pb, and Pt is completed, the control microcomputer 11 ends all processing.

In addition, the welding can 8 is attached to the above three bases j (Q point 1) d.

When the welding robot is positioned at Pb and Pc, the posture of -1 may be arbitrary (this will be discussed later).

The three reference points Pa, Pb, and Pc are three points that are not on a predetermined straight line in the operating area of the welding day bot 1, as shown in FIG. 2, and are set, for example, on specific equipment within the operating area. Alternatively, a welding point on the workpiece to be welded can be used.

Note that here, three points on the equipment that are not on a predetermined straight line are defined as reference points Pa, Pb, and Pc.

Therefore, this reference point P is stored in the teach data memory 20 before maintenance or when teaching welding points.
It is assumed that the movement amount data of each axis of the robot regarding a, Pb, and PC are stored by teaching.

Of course, if the welding point is used as the reference point, such teaching is not necessary.

On the other hand, if 1, for example, selects the teach mode and turns on the sampling switch 21 when the correction mode switch 13 is turned on, the correction microcomputer 12 proceeds to 5TIEP8.9 in the processing program flowchart shown in FIG. 5
Reference points Pa, Pb from control microcomputer 11 with TEPIO
, after checking whether the transfer of operation amount data regarding Pc has been completed.

If it has not finished, it waits until it receives the transfer data at 5TEPII.

Then, the correction microcomputer 12 calculates the amount of movement of each axis of the robot with respect to the example scale i' (+4 points P a ) transferred from the control microcomputer 11 01a' + 02a' +7
? 3a' + 04a'HOGa' r OGa'
When the received data is received, it is stored in the internal RAM of the correction microcomputer 12 at 5TEP 12, and then
Proceeding to TIEP13, the following analysis processing is performed.

In other words, the new installation position of the heavy robot 1 is set to the origin 0'
The reference point P (P a , P b , P c ) in the new orthogonal coordinate system (0'; i, ', J')
When the tip of the welding gun 8 is positioned at this reference point P, the direction vector of the approach direction of the welding gun 8 to the reference point P is expressed as Direction Muku 1 Hell V (shi.

U can be expressed as three angles using Euler angles) is ['p(P, u, η]) = [lvl,]XI
F θ (θ 1 , θ 2+ / 3+ 04+ O
s, 6G). Here pp is p, u, U or neo-orthogonal drift system (O′; sig, , j
l.

'), and Pa is θI
~06 represents data in the local coordinate system of each axis of the robot.

Further, [Ml] is a coordinate transformation matrix, which can be determined by the axis configuration of welding holes l~1.

Specific examples of the above conversion formulas are as follows.

Sunawachi, E″0', E″”l E'°”,
E", 'Ele' respectively the first rotating shaft 3A, the first
Swivel axis 5. Let the rotational transformation matrix (rotation tensor) around the L-axis, j-axis, and axis in the local coordinates ('y js k) of the second rotation axis 6° and the third rotation axis 7, and v
If o is the base 7 (q normal beta 1-ru (direction back 1-ru indicating the gripping direction of the welding gun 8 when all O is rOJ), then p(z, !f, z) = C kidney + c% 10 E=1”(
tj, )+ E'E""E" (c fang) 10 E"IEJθ rEJ both E'J (C, 7+Q",
) ・−・・−=,, (pu(tLl, u 2 ,
u 3 ) :E”E”’E”’E” (Cj +
cj ) − ■ side (υ1.υ2.υ, ) = EkBI
E″J19jEegareE”’ (υ.)・・・・・・
・It becomes like ■(C?, Car L 4
r C41Cj r G 4 see Figure 2].

However, since the direction vectors I and V, which are the posture information of the welding robot 1, are not used in the present invention, only the coordinate position data (x, y, Z) of the reference point P will be calculated.

That is, since the direction vector is used and υ is not used, the posture of the welding robot 1 when the tip of the welding ring 8 is determined as the reference point at position II'1 may be arbitrary.

Sokote, 5TIE+) 13 Te is 5TIEP12TeRA M d Operation amount 0+i regarding the stored reference point Pa
+ (h'&+ 7?Ji +04'a+ 05K
+ Read Oj6, perform analysis processing using the +j+ formula, and create the new orthogonal coordinate system (Q';i'+j'r'')
JfV of reference point Pa at , drift position theta Pa' (
CCa',,! /a', Za') is subtracted by j.

Next, I won at 5TEP14 and 5TIEP13:'
d' (x B 'ya', Za') as internal RA
After storing in M, return to 5TEPIO and store 5TEI'lO
White box 1 - operation amount of each axis 0+b+02'b+β tail regarding reference points Pb and Pc sequentially transferred from control microcomputer 11 in a loop of ~14.

04b y 05'b r OGb + (++c r
02C, βJC! 04C+051: Analyze t θc2 in the same manner as described above, and obtain Pb'(zb' , yb' , zb' L Pc
'(Occ',yc' zc/) is stored in the internal RAM.

When the data transfer from the control microcomputer 11 is completed, the process advances from 5TEP20 to 5TEPI5. 5TEP
At I5, it is checked whether the correction switch 22 is turned on or not. If it is not turned on, the process returns to S'TIEP9, and if it is turned on, the process goes to 5TEP16.

Note that if the sampling switch S is also turned off when the correction switch 22 is turned off, the loop of 5TIEP9 and 15 is repeated, and if the data transfer is completed even if the sampling switch 9 is turned on, the loop is 5TEP9.

10 and 15 loops are repeated].

Therefore, when the correction switch 22 is turned on, the correction microcomputer 12 proceeds to 5TEP16, and from the teach delta memory 20, the reference point P that was taught before the installation error occurred.
Robot each axis movement regarding a, Pb, P'c jjk e
1a～Oea t θtb-Osb y e 1c
After sequentially reading ~esc, these □1a~06a+ 01b~(' 6b+ 01C~0
6G <31'[Er'13 is performed to analyze the teaching data stored in the teach data memory 20 or the defined old orthogonal reference system, that is, in this embodiment, before maintenance. Welding robots 1-
Coordinate position data P of reference points Pa, pb, and Pc in the orthogonal coordinate system (0; =, jt k) (see Figure 2)
a (za, ya, za), Pb (zb, yb, zbLP
Find c (OCc, yc, Zc).

Then, the resulting coordinate position data Pa, I)b.

Once the PC is stored in the internal RAM with 5TEP18, it is 51
Proceed to Er'19.

In 5TEP19, the old orthogonal coordinate system (0; =, js k
> and the new orthogonal coordinate system (01; ,' I , J l ,
/l), ΔX, Δy, and Δ2 represent the amount of translation in each axis direction from 0 to 0'.

To find out, we perform the following calculations.

That is, 5TEP14.18te internal RA, M 2 storage coordinate position data P'a, P'b, P
c, P a , P b .

By setting up simultaneous equations of the following order and solving these equations, the coordinate transformations 71 to M2 are obtained and stored in the internal RAM.

Next, in 5TEP20, the teach data in the old orthogonal coordinate system that was used before the installation error occurred and is stored in the teach data memory 20 [movement of each robot axisffl 01A+ 02A+ 7?3A+ 04j+
O5JLrO6λ (i=1 to n, 11 is the number of teach data points)] is read from i=t, and 5TEI
In 121, analysis processing based on the above-mentioned equations 1, L) to (Y) is performed, and the old orthogonal coordinate system (0; 'r
Pi (zi, yL, zi,) at j+k), u
L(tz L,.

uL2. fti, 3), vi (2) i, (,uL2
．． Enter ui, 3).

Then, at 5TEP22, the coordinate transformation 71-rix M2 stored in the internal RAM is read out, and Pi(P, 1.

ui, 'Iui) = M2 Pi-' (P i', u
L'.

1))i'), that is, the following coordinate transformation formula is established to create the new orthogonal coordinate system (01; , ", j/.

p i' ($ L', 5 L',
Z j' ).

u L'Cu L1', u1-2'g
U L! ).

By performing the following synthesis process in 5TEP23, new teach data [θ
1 engineering', θ2J' + '32' + 044' p
O5A' * θ64' (si=1-n)].

That is, P'jil= ((JIA' + (J2i
' + lsi'+04A' y O5A' y θ
62'), =f(OcL/, 5i,'.

Zi', fliI', 1tia', ui,
3', tlL+', υi3'υL3'), the function f becomes a complex non-linear form, but in the equation 0 mentioned above, CF = R12 ("12.!l12y 212
) E"'E"' (Lj) = R34(T-z4t
! l 3at Z 34) E"E"' proof = 90 y (C! ) = Rse (0cssy y 56z
Zss) E″' E”” E” v=″((j + Gj
) = R? 8(”7111 N 781 Z ?+1
), then θ1r02+ 7?3 is.

0 engineering = jan-' (!t 34/ x34) θ2
== t, an −' (-i-734/ n )I
It can be expressed as 3 = 77; 42.

Also, E″ex+ Etc-e″’ R78-(x'k
, Hk r Z k), then 04r 05 is.

σ4 ``Shian-'' (Hk /'x k )0 5
=4an-' (± zk/〆;)wa'c+y''/e)
It can be expressed as

Furthermore, if we transform the equation 0 mentioned above.

ER(4J)EII(-tja>1(-θ"E"")
(v)=E"' (4y.), and since the left side of this equation can be assumed to be known, we can write this as ("+ + !lI+
z + ) and vo (”or !t o + z
o), then 06 is 06=tan-” [(-z
oMs+9oZs)/(yoyl+zOzI)].

Therefore, new teach data can be obtained by calculating each of the above equations.

Next, at 5TEP24, after storing the new teach data obtained at ST[P23 in the teach data memory 20,
At 5TEP25, check whether the process is finished with i = H. If it is not finished, return to ST [EP20 and 5TE
Each process from P20 to P24 is repeated, and if completed, the correction process is ended.

Then, after completing the correction of the teaching data mentioned above, select the playback mode and start the welding robot 1.
The same welding work as before maintenance can be performed.

In the above embodiment, the case where the teach data of a welding robot is corrected is described, but this is not limited to this and can be applied to the case where the teach data of any playback type robot is corrected. The invention is equally applicable.

Furthermore, the present invention can be similarly applied to correction of teaching data when teaching the robot I- at a location other than the installation location, or when performing automatic teaching on data using a CAD system, which has been actively developed in recent years.

As explained above, according to this invention, robots 1
-Using itself as a measuring device, a coordinate transformation matrix is determined by measuring three reference points that are not on a predetermined straight line, and the teach data is corrected based on the coordinate transformation matrix. This eliminates the need for dedicated 11+ positioning equipment as in the past, which not only greatly reduces maintenance costs, but also makes it easier to maintain multiple robots on the assembly line at once, or even modify the assembly line itself. , correction of teaching data associated with this and correction of teaching data based on pre-teaching work performed at another location can be easily performed, without significantly reducing the operating rate of the line.

Also, it is not possible to secure a sufficient work area around the robot (but the teaching data can be corrected).

[Brief explanation of drawings]

FIG. 1 is an external view of a multi-axis robot showing an embodiment of the present invention. FIG. 2 is a skeleton diagram for explaining the motion functions of the multi-axis robot shown in FIG. 1 using graphical symbols. FIG. 3 is a block diagram of the control system of the welding robot 1 shown in FIGS. 1 and 2. , FIG. 4 is a flowchart showing a part of the processing program of the robot control microcomputer shown in FIG. 3, and FIG. 5 is a flowchart showing an outline of the processing program of the correction microcomputer shown in FIG. 1... Welding robot I-9... Control device 10... Teaching box 11... Robot control microcomputer 12.
...Correction microcomputer 13...Correction mode changeover switch 14.19.23...Interface circuit 18A~
18F...Axis position detector 20...Teach data memory 21...Sampling switch 22...Correction switch Fig. 1 Fig. 2

Claims (1)

[Claims] 1. In a multi-axis robot equipped with an axis position detector on each axis, the position of each axis is detected when the working end of the multi-axis robot is positioned at each of three reference points that are not on a predetermined straight line in its operating area. After determining the coordinate position data of the three reference points in the new orthogonal coordinate system of the currently installed multi-axis robot based on the movement amount of each axis muscle obtained from the device, the coordinate position data of these three and the coordinate position data of the three reference points in the old orthogonal coordinate system in which the teach data of the multi-axis robot is defined. A method for correcting teach data for a robot, comprising correcting teach data for the multi-axis robot based on a coordinate transformation matrix that has been calculated.