JPS6198410A - Robot teaching method - Google Patents

Abstract

PURPOSE:To obtain the accurate relative relation among a visual coordinate system, a robot coordinate system and the position and the reference angle of a robot hand, by recognizing the main shaft angle of a work as well as the centroid of the work where the holding state is decided unconditionally through a visual device of the robot. CONSTITUTION:A visual device 11 can recognize the centroid position and the angle of the main shaft of a work 8 at the planar coordinates. The work 8 is positioned by means a hand 6 turned in the reference direction, a work with which the positional relation between the work and the hand 6 under a holding mode and said device 11. Then the centroid position of the work 8 is recognized by the device 11 at >=2 teaching points. At the same time, the angle of the main shaft of the work 8 is recognized at >=1 teaching points. Thus the relative position of an original point and the relative relations of the inclination of the coordinates, the reference angle, magnification factor of the hand 6, etc. can be obtained easily among a visual coordinate system OV, a robot coordinate system OR and the hand 6 based on the results of said recognition and the shift amount of the robot obtained in response to the >=2 teaching points.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a coordinate system that determines the relative relationship between a visual coordinate system, a robot coordinate system, and the position and reference orientation of a hand in a robot combined with a visual device. This relates to a teaching method.

[Background of the invention]

In robots such as industrial robots, there are many methods in which a human being directly or indirectly teaches the robot to perform a task, memorizes the motion, and then reproduces the motion.

For example, when such a robot handles a work, the work to be handled needs to be accurately positioned at the location determined at the time of teaching, but this work is difficult.

+1 ゝ In order to solve this kind of problem, it is sufficient to attach a visual device to the robot so that it can recognize the position, posture shape, etc. of the workpiece and perform the hand 1 nonce. Handling is relatively easy.

In this case, it is necessary to give the relative relationship between the coordinate system of the visual device and the coordinate system of the robot in advance, and as shown in Japanese Patent Laid-Open No. 58-114887, visual coordinates can be determined by recognizing mark coordinates. The relative position of the origin in the system and the robot coordinate system.

A method for finding the rotation magnification of the coordinate axes is known.

However, with this method, it is necessary to accurately determine the mark position. Furthermore, there is no description of a method for determining the relative positional relationship between the visual device and the hand when the visual device is attached to the arm of the robot. Furthermore, in operations where the hand can be rotated to grasp a workpiece in a predetermined orientation, it is necessary to instruct the rotation angle from the hand angle in the reference orientation, and the reference angle 1 of this hand must also be given in advance. There is.

[Purpose of the invention]

In order to solve the problems of the prior art described above, the present invention uses the robot itself as a measuring device and easily determines the relative relationship between the visual coordinate system, the robot coordinate system, and the position and reference orientation of the hand. Its purpose is to provide a method.

[Summary of the invention]

In order to achieve the above object, the present invention provides a visual device that can recognize at least the centroid position and principal axis angle of a workpiece in plane coordinates, and a unique positional and angular relationship between the hand and the workpiece when gripping. Using a workpiece determined by
By using the visual device to recognize the centroid position of the workpiece at two or more teaching points and recognizing the principal axis angle of the workpiece at one or more teaching points, these recognition results and the two
The visual coordinate system is determined from the amount of robot movement found in response to the teaching points that are more than one point.

The relative relationships between the robot coordinate system and the hand, such as the relative position of the origin, the inclination of the coordinate axes, and the reference angle 9 magnification (ratio dimension) of the hand, are easily determined.

[Embodiments of the invention]

Hereinafter, the present invention will be explained in detail by way of examples.

FIG. 1 shows an embodiment of the present invention, and is a diagram showing the configuration and operation of a Cartesian coordinate robot 1 in which a visual device is attached to a moving arm. 2 is the workbench, 3 is the fixed arm of the robot,
4 is a horizontally movable arm movable in the z and y directions on the fixed arm; 5 is a vertically movable arm movable in the upper F direction with respect to the horizontally movable arm 4; 8 is the workpiece; 6 is the vertically movable arm 5. A hand 7 attached to the bottom and gripping the work 8
is a visual device using a video camera or the like attached to the tip of the horizontally moving arm 4. Further, 9 is the visual field of the visual device 7 on the workbench 2, (XR-OR-YR) is the robot coordinate system, (Xv-Ov-Yv) is the visual coordinate system,
The origin of the visual coordinate system changes to Ova, Ovb, and Ovc in accordance with the movement position of the horizontally moving arm 4, and visual fields 9a, 9b, and 9c correspond to each of these origins, respectively.

Further, point P is a point on a straight line a passing through the origin of the node 6 and parallel to the vertically movable arm 5, and is a reference point for the node 6.

□ Ring Next, FIG. 2 shows a specific example of a gripping state between a pair of fingers 6a and a teaching workpiece 8a whose positional relationship and angular relationship when gripping are uniquely determined.

In this figure, the pair of gripping surfaces 6a are parallel to each other and have a rectangular cross section, and the teaching workpiece 8a is symmetrical in the shape of a single character. As a result, the angle θ formed between the I-end direction line, which indicates the direction of the hand connecting the centers of the pair of no-knots 63, and the main axis of the workpiece 8a.
Become a grasper who makes a right angle. In addition, point P is the handling reference point for the handle 6a, HA is the reference point for handling the workpiece 8a, point C is the centroid of the workpiece 8a, and in the case of Figure 2, point P, point H, 6 points will match.

In the above configuration, the operations of the robot 1 and the visual device 7 will be explained based on the flowchart shown in FIG. 9.

(1) After gripping the rework 8a with the hand 6a facing the &
The workpiece 8a is positioned so that the handling reference point P of a coincides with the handling reference point H and the centroid C of the workpiece 8a, and at the same time, the angle θH between the hand direction line JH and the workpiece main @LP forms a right angle. Ru. Further, 9a is the visual field of the visual device 7 at this time, and Qva is the origin of the visual coordinate system.

(2) Operate the robot and move the visual device 7 by △XR, △YR in the robot coordinate system so that the workpiece 8a positioned in (1) comes into the visual field of the visual device 7 (
The centroid of the workpiece in the visual coordinate system is determined by the visual device 7.

Recognize Rin (Xv, , Yv, ) and the principal axis angle θ (J in the same figure). 9b is the visual field of the visual device 7 at this time, and Ovb is taken at the origin of the visual locus system.

(3) Set the visual device 7 within the range where the workpiece 8a comes into view,
From the state (2), ΔXR is further calculated in the robot coordinate system.
,, After moving ΔYR2 (k in the same figure), the visual device 7 again
The centroid coordinates of the workpiece in the visual coordinate system (Xv2.
Yv, ) (L in the same figure). 9C is the visual field of the visual device 7 at this time, and Qvc is the origin of the visual coordinate system.

(4) Through the above operations, the robot moves ′j#(ΔXR
,.

ΔYR, ), (ΔXR,, ΔYR,) and recognition by visual device 1. ? , -centroid coordinates (Xv, , YV, ), (X
v2. Using Yv2) and the principal axis angle θ, the teaching data (relative relationship of the coordinate system) is determined (m in the same figure).

Next, the teaching data calculation method in item (4) above will be explained.

FIG. 3 shows hands 6a and I having a rectangular cross-sectional shape in FIG.
The above (1) when using the shaped work 8a,
It is a figure which shows the relationship of each coordinate system corresponding to the operation|movement of (2) and (3).

In addition, Konozu Nioite, Xv a-Ov a-Yv a
, Xv b-Ovb-Yvb and Xvc-OVC-Y
VC is (1) each.

Visual coordinate system, XR-O in the movements of (2) and (3)
R-YR is the robot coordinate system, p and a are the handling base points of the hand 6a in the operation (1), ΔXH, ΔYH
teeth.

Each represents the two coordinates and y coordinate of point P with respect to the visual coordinate origin Qva in the robot coordinate system.

Further, α and β are the concealment rate (relative dimension) of the robot coordinate system with respect to the visual coordinate system in Z and seven directions, respectively, and θ. is the tilt of the visual coordinate system with respect to the robot coordinate system.

Here, the following relational expression holds true for each seat value in FIG.

・・・・・・■ ΔXR2cos4-1−ΔYR2sinθo==a(X
v, -Xv2) -=■ΔXR2sinθ0−ΔYR,
CO5θ. =β (Yv2-Yv, ) ---■
∆ collapse = ∆XR, + (α, Xv1 cos θ. - βYv, s
inθo)・Slap・■ΔYH=ΔYR, +(αXv, si
nθ. +βYv, cosOo) , , , , ■ α, β, θ from the above formulas 0 to 0. , ΔXH, and ΔYH are found, and β/α in the equation (2) is a value that can also be found from the hardware structure of the visual device.

Furthermore, Fig. 4 is a diagram showing the angular relationship when the hand grips a workpiece in each coordinate system corresponding to the above operations (1) and (2) @, and the position of the hand corresponds to the operation described in (1). are doing. In this figure, the same symbols as in FIGS. 1 and 2 indicate the same parts.

Moreover, θS is the angle formed by the hand direction line JH in the robot coordinate system when the hand is facing the reference direction. The following relational expression holds true for the angles shown in FIG.

θS=θ+θ. -θH・beat・■ In this equation, as mentioned above, θ. is the value found from the related equations from ■ to ■, and θH is the known value (in Fig. 4, the second
As in the case of the figure, θH=90°), so θS can be found by recognizing the principal axis angle of 1 degree θ of the workpiece 8a using the visual device.

, 1 1' Therefore, the If ratio of the robot coordinate system with respect to the visual coordinate system (
Relative dimensions) α, β, inclination θ of the visual coordinate system with respect to the robot coordinate system. , the reference point y'r-, yzarin(
ΔXH, ΔYH), and the angle θS of the direction line facing the reference direction in the robot coordinate system.

By the way, the above-mentioned relational expressions from ■ to ■ apply not only to the case of the hand 6a with a rectangular cross section and the single-shaped workpiece 8a as shown in FIG. 2, but also to the case of the wedge-shaped hand 6b shown in FIG. As in the case of workpiece 8b corresponding to This relational expression holds true if the angle formed can be uniquely determined.

Furthermore, as shown in FIG. 6, the workpiece 8 is
When gripping C, if the gripping relationship between the hand and the workpiece is fixed, in other words, the hand direction line 1 of hand 6C facing the reference direction in the 10-bot coordinate system in Figure 6.
1 (the angle θS of
Even when the distance e between the handling reference point H at point C and point C (see Figure 1) has been determined, the same operations as in Figs. 1 and 9 can be performed.

In this case, the above-mentioned equations (■, It is necessary to use the following equation in which the positional relationship between the handling reference point H and the centroid C of the workpiece is corrected as XH"muYw").

△XH"= △Xl(-e cos (θS+θH)
−−−−−−■△Y H'=△YH−esin(θS
+θH)
By the operations in 2) and (3), the visual device's movement distance M XR2, ΔYR2 and the corresponding amount when the centroid coordinates of the workpiece placed at a fixed position are recognized at two points by moving the viewing platform @7. 2
Centroid coordinates at the point (Xv, +”v+ ), (Xv2
．． Yv2) is used, and is unrelated to the gripping state of the workpiece by the hand, which is determined from the operation in item (1) above.

Therefore, in the processing corresponding to the operations (2) and (3), the workpiece may be of any shape as long as it falls within the field of view at the visual position g and the centroid can be recognized. As a result, by using a workpiece of an arbitrary shape and moving the viewing device by a predetermined amount, the centroid coordinates of the arbitrary workpiece placed at a fixed position can be set by 2.
By recognizing points, the magnification (specific dimensions) α, β of the robot coordinate system with respect to the visual coordinate system and the inclination θ of the visual coordinate system with respect to the robot coordinate system. Can you find the relative relationships such as

Next, FIG. 7 shows another embodiment according to the present invention, and is a diagram showing the configuration and operation of a robot 10 in which the visual device 11 is provided separately from the moving arm of a Cartesian coordinate robot that moves in one direction. In this figure, parts with the same prefixes as in Figure 1 indicate the same parts. 12 is a fixture for fixing the visual device 11, and visual device #11 is a fixture. 12 to fix it in a certain position.

In other words, in the robot coordinate system XR-OR-YR,
The visual coordinate system Xv-Ov-Yv is positioned in a certain relative relationship (displacement of the origin, inclination of the coordinate axes). and,
13 is the visual field of the visual device 11 at this time.

In the above configuration, the operations of the robot 10 and the visual device 11 will be explained based on the flowchart shown in FIG.

(a) After gripping the workpiece 8 with the hand 6 facing the reference direction of the robot 10, ΔX in the robot coordinate system
R,', ΔYR,', and place the work 8 at position A, which is within the field of view 13 (r in the figure). And here visual device 1
1, the centroid coordinate CXv of the workpiece 8 in the visual coordinate system
, Yv,) and the spindle angle θ (see figure 5) (b) Furthermore, the robot 10 moves the workpiece 8 to the mouth J'') coordinate system by 71°ゝ゛′°・°“′°ゝゝ)1 and placed it at another B position within the visual field 13 (1 in the same figure), the visual device 11 again recognizes the centroid coordinates (Xvt, Yv,) of the workpiece 80 in the visual coordinate system (1 in the same figure). , u).

(C) Through the above operations, the robot movement amount (ΔXR
1”.

ΔYR, °), (muxR21, ΔY−°) are recognized by the visual device 1, Ta centroid m (Xv, , Yv, ), (
The teaching data (relative relationship of the coordinate system) is obtained using the main axis angle θ (Xv, , Yv, ) and the principal axis angle θ (FIG. 4, v).

Next, the method for outputting teaching data>J in the above section (C) will be explained.

Furthermore, Fig. 8 shows that the reference point of the handling reference point P of the handle when gripping a workpiece is set to the origin OR of the robot coordinate system.
2 is a diagram showing the relationship between the respective coordinate systems corresponding to the operations of (a) and (b) above when using the rectangular cross-section huft drawer a of FIG. 2 and the single-character-shaped work 8a. In this figure, points P, , and P are the I-nd ring reference points of the second and second positions at the A position and B position of the workpiece, respectively, and P
, , P2 coincide with the no-end ring reference point H and the centroid C of the workpiece.
! Furthermore, Ov (ΔXv, ΔYv) is the coordinate of the current visual coordinate origin in the robot sitting reference system, Pl (ΔXR, ″,
ΔYR,') is the seated image of the non-end ring reference point H of the workpiece 11a at the A position, and is the final value from the robot movement amount in term (a). Also, as in the case of Fig. 6, α, β
are the magnifications of the robot coordinate system with respect to the visual coordinate system in the z and y directions, respectively, and θ0 is the inclination of the visual coordinate system with respect to the robot coordinate system.Here, the following relational expression holds true for each coordinate value in Figure 8. do.

・・・・・・■ ΔXR2cosθ6 + ΔY 'R2Slnθ. =-
α(Xv, -xv2)---@ΔXR, Sinθ
. −ΔY R2CO5θ. = −72(Yv2− Y'
/, ＞−・・−・■ΔXv=ΔXR, −(αXv,
cos θ. −βYv, sinθo) − Hit 6 @△Yv=
ΔY R, - (aXv, sin θ. 1βYv, c
osθ. )・Song・0 and from the above 0 to 0 formula α, β, θ
. , △Xv, △Yv are calculated as 1, but in the formula, 7θ/α is,
As in the case of Figure 6, from the hardware structure of the visual device,
This is the value to be found.

By the way, in the 0-0 formula.

Mu person R, = -△inR1ΔIR, = -ΔXR.

ΔXR2'=-△XR, ΔYR2' Knee-△YR2Δ
Xv=-ΔXHΔYv=-ΔY If the positive and negative signs of H are reversed and replaced, the 0-0 formula becomes exactly the same as the 0-0 formula. This is because the coordinate relationship between the visual device and the workpiece in FIGS. 1 and 7 is opposite to the movement of the robot.

Furthermore, corresponding to the operation in item (a) above, as the angular relationship in each coordinate system when gripping the workpiece by...
As in the case of FIG. 1, if the relationship shown in % FIG. 4 holds, then the following [phase] equation, which is exactly equal to the 0 equation, holds true.

θS=θ+θ0−θH...[Phase] And in this equation, θ. (2) The value obtained from formula (1), θH, is a known value (θH=90° in FIG. 4 as in the case of FIG. 2).

θS is determined by recognizing the main flIl usage θ of the workpiece 8a using a visual device.

Therefore, in the case of FIG. 7, by the same processing as in FIG. 1, the magnification (ratio dimension) α of the robot coordinate system with respect to the visual coordinate system,
β, the inclination of the visual coordinate system with respect to the robot coordinate system, the coordinates of the visual i-collar origin position in the robot coordinate system (ΔXV,
ΔYV), the angle θS of the hand direction line of the hand facing the reference direction in the robot coordinate thread, etc., and the relative relationships of the coordinate systems can be determined.

In addition, the above-mentioned equations 1 to 1, as in the case of FIG. 1, are similar to the case of FIG. This relational expression holds true when the centroid C coincides with the centroid C, the handling reference point P of the hand coincides, and the angle θH between the hand direction line LH and the main axis LP of the workpiece is uniquely determined.

Furthermore, as shown in FIG. 6, when a workpiece 8C is gripped by a hand 6C, even if the gripping relationship between the hand and the workpiece is determined to be constant, FIGS. As in the case of , the above equations 0 to 0 remain unchanged, and the coordinates (ΔXv', ΔYv') of the visual coordinate origin in the robot coordinate system corresponding to equations 2 and 0 are also the handling reference point H of the workpiece. It can be obtained using the following formula, which corrects the deviation from the centroid C.

△X V' = ΔXv -4-e cos (θS
+θH) ・・River◎ΔYv' =ΔYv −4−e
sin (θS+θH) −−−−−−t@rIn the case of Fig. 7, the workpiece is moved 2 times by the robot hand.
If a workpiece is used in which the gripping relationship is not fixed when the hand grips the workpiece because the workpiece is moved by gripping the workpiece twice, the equations 0 to 69 will not hold true.

By the way, in the explanations so far, in the robot configuration shown in FIG. 1 and the robot configuration shown in FIG. The relative relationship of the coordinate systems between the visual coordinate system, the robot coordinate system, and the position and reference angle of the hand has been determined from the principal axis angle in the visual coordinate at a point, but the present invention is not limited to this.

In Figure 9, J- is required times (n) or in Figure 10, t.
By repeating IU as many times as necessary (W), the relative relationships of the coordinate systems can be found in the same way even when two or more teaching points are used.

For example, if the teaching points are set to 3 points (in Figure 9, n
= 2 or W = 2) in Figure 10.

In Figures 1 and 5, the centroid coordinates in the visual coordinate system at the teaching point in Figure 3 are (Xv3. Y Vs,), and the robot coordinate system when moving from the second to the sixth teaching point The amount of movement of the visual device at is ΔXR.

When ΔYR3 is assumed, the following equation further holds true.

......■ Therefore, the values of α and β can be obtained from ■ and formula 0. In Figures 7 and 8, the centroid coordinates in the visual coordinate system at the third teaching point are ( Xv3.Yv3) and the second
The amount of movement of the workpiece in the robot coordinate system when moving from to the fifth teaching point is ΔXR,°, ΔYa,.

Then, the following equation holds true: . . .■ Therefore, the values of α and β can be obtained from ■ and Equation C.

From this, the robot configurations in Figures 1 and 7 are
By using the third teaching point, it becomes easier to obtain the values of α and β.

In addition, in the explanations so far, both the robot configurations in FIGS. 1 and 7 each have one time in the visual coordinate system at the time corresponding to the j term in the flowchart in FIG. 9 and the term 5 in the flowchart in FIG. 10. By measuring the main axis angle, we have determined the angle θS of the hand direction line in the robot coordinate system when the hand is facing the reference direction, but this is not limited to this. The principal axis angle may be measured at a time point corresponding to the U term in , or alternatively, each may be measured a plurality of times and an averaged value may be used.

By the way, for the actual work handling operation by the robot, teaching data is obtained in advance, and using this teaching data, the robot movement amount data (Xa) is determined from the recognition result by the visual device.

It is conceivable to calculate the YR direction movement amount and rotation angle) and operate the robot based on this data.

An example of the equipment configuration of the entire system in this case is shown in the first example.
Shown in Figure 1. In FIG. 11, 18 is a visual device consisting of an image input device 16 such as a video camera and an image processing device #17 for processing the input image, 19 is a robot, and 20 is a computing device such as a personal computer used for teaching. .

In the above configuration, when teaching.

The communication lines 21 and 22 are connected, the robot is operated according to instructions from the computing device 20, and the amount of robot movement at this time is input to the computing device 20. At the same time, the recognition results (centroid, principal axis angle) by the visual device 18 are received. input into the calculation device 20,
The calculation device 20 calculates the formula ■~Sada [stock],
The teaching data (relative coordinate system relationship) is calculated, and the calculated teaching data is transferred to the image processing device 17 and stored.

Next, during actual work handling, the computing device 20 is removed, only the communication line 26 is connected, and the image input device 16 is connected.
The image is taken into the image processing device 17, where the centroid and spindle angle of the workpiece are recognized, and at the same time, robot movement amount data is calculated and this data is transferred to the robot 19 to perform 71/drilling of the workpiece.

As a result, the calculation processing in the visual device 1B can be reduced.
At w1, since the computing device 20 is required only for teaching and not for work handling, one computing device #20 is required for multiple combinations of the visual device 1B and the robot 19.
This means that the entire system can be constructed at low cost.

In addition, in the explanation so far, we have described a method for automatically measuring the relative relationship between the visual coordinate system in a flat plane and the robot coordinate system, as well as the position and reference angle, using a visual device for Cartesian coordinate robots. But this is the only method! Instead of one cylindrical coordinate system, the pole P!
l! W thread, scara shape.

Even if it is a robot of other forms such as Sekkan IIo type! .

It is clear that the present invention can be applied as is to any robot whose movement amount can be specified using a rectangular coordinate system in the y direction, and can even be extended to three-dimensional coordinates that include two directions.

Furthermore, in the above explanation, we have described a method for determining the relative relationship of coordinate systems in a robot combined with a visual device, but this method is not limited to robots, but can be applied to any device that operates in combination with a visual device. [Effects of the Invention] As described above in detail, according to the present invention, it can be generally applied to the case of determining the relative relationship between coordinates.

A visual device used in combination with the robot is used as a measuring device, and the centroid coordinates of the workpiece, where the grasping state of the hand is uniquely determined, are recognized at two or more points within the field of view of the visual device. With a simple operation of recognizing the main axis angle of the workpiece at one or more points, it is possible to accurately determine the relative relationship between the visual coordinate system, the robot coordinate system, and the hunt position/reference angle. It is also very effective in terms of measurements, etc.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration and operation of a Cartesian coordinate robot equipped with a visual device according to an embodiment of the present invention, and FIG.
FIG. 5 is a diagram showing a state in which an engineering-shaped workpiece is gripped by a hand having a rectangular cross section. Diagram showing the coordinate relationship in the robot motion of Fig. 1, Fig. 4
The figure shows the gripping angle state in the robot operation of FIGS. 1 and 7 (described later). 6
The figure shows the grasping state of the hand and the workpiece in a workpiece in which the reference point and centroid of the workpiece are in a fixed positional relationship, and FIG. Figure 8 is a diagram showing the configuration and operation of a Cartesian robot placed separately. Figure 8 is a diagram showing the coordinate relationship in the robot operation of Figure 7. Figures 9 and 10 are diagrams showing the operation of the robot and visual device. The flowchart shown in FIG. 11 is a diagram showing an example of the equipment configuration of the overall system of the present invention.Explanation of symbols 1.10...Robot, 4...Horizontal moving arm, 5 ... Vertical movement arm. 6.6a, 6b, 6C - Hitting / Hand, 7.11 ... Visual device, 8.8a, 8b, 8c - Hitting / '7- Ri. q , 9a, 9b, 9c, 1S --- Visual field of view XR-OR-YR--Robot coordinate system, Xv-O
v-Yv-・Visual coordinate system, P...Hand handling reference point. H... Workpiece handling reference point, C...
...The center of gravity of the work. Hi

Claims (1)

[Claims] 1. In a robot combined with a visual device capable of recognizing at least the centroid position and principal axis angle of a workpiece in plane coordinates, the positional and angular relationships between the hand and the workpiece when gripped by the hand are Using a uniquely determined teaching workpiece, the robot is moved with the hand in a reference direction, and the center of gravity of the workpiece is recognized at two or more teaching points within the visual field of the visual device. By recognizing the main axis angle of the workpiece at one or more teaching points, the centroid coordinates at the two or more teaching points and the main axis angle at one or more teaching points in the visual coordinate system determined at this time and the robot From the robot movement amount corresponding to the two or more teaching points in the coordinate system, the relative relationship between the visual coordinate system and the robot coordinate system, as well as the position and reference orientation of the robot's hand is determined. A robot teaching method characterized by the following. 2. Attach the visual device to the movable arm of the robot, once grip the teaching workpiece with the robot's hand pointing in the reference direction, release it and position it, and then move the visual device. Recognize the centroid coordinates at the two or more teaching points on the visual coordinate system and the principal axis angle at the one or more teaching points, and set the visual device movement amount in the robot coordinate system as the robot movement amount. A method for teaching a robot according to claim 1, characterized in that: 3. By installing the visual device separately from the robot and moving the teaching workpiece with the robot's hand pointing in the reference direction, a diagram at the two or more teaching points on the visual coordinate system can be obtained. The robot according to claim 1, wherein the center coordinate and the main axis angle at the one or more teaching points are recognized, and the workpiece movement amount in the robot coordinate system is taken as the robot movement amount. Teaching method.