JPS63120088A - Method of correcting position of unmanned cart loading robot - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is an automated guided vehicle equipped with a robot, and is capable of moving to multiple remote locations to perform work. Regarding Mi correct method.

``Prior Art'' Conventionally, a robot mounted on an automatic guided vehicle completes a given task by repeating a series of operations in which the automatic guided vehicle transports the robot to a working position, and then the robot performs the work.

Some robots of this type are designed to memorize teaching points that have been taught in advance regarding the workpiece, and play back by following this memory, and are called teaching-playback type robots. .

When a teasing/playback type robot performs work, the robot's operating point (generally the tip of the arm)
The relative position between the robot and the workpiece must be known at all times, and for this purpose, the automatic guided vehicle must be stopped at a fixed position relative to the workpiece.

Conventionally, the following two methods have been adopted as stopping methods to achieve this.

(1) A mechanical positioning device at the stop position of the automatic guided vehicle,
For example, a device is provided to press the automated guided vehicle against a rail or cone, and this is used to position the vehicle.

(2) Confirm the position of the workpiece using a visual sensor, and
l [The teaching point is corrected and operated according to the amount of deviation from the position when the person carrier is in its normal position.

"Problems to be Solved by the Invention" By the way, the conventional position correction method described above has the following drawbacks.

(A) In method 1 above, since the automatic guided vehicle is driven by tires, it is difficult to position it in the lateral direction. Additionally, positioning devices must be installed at all working positions, which increases space and cost. Furthermore, positioning is impossible in locations where a positioning device cannot be installed.

(B) In the method (2) above, a visual sensor that can precisely grasp the position of the workpiece becomes extremely expensive.

Furthermore, since image processing must be performed, advanced technological capabilities and investment are required.

In response to this problem, the applicant has proposed a system equipped with an automatic guided vehicle that transports the robot mounted on the automatic guided vehicle to a working position and performs work on a workpiece placed at the working position according to teaching points taught in advance. The robot includes a mark recorded at a predetermined location of the work position and an image detection means attached to the robot, and after the automatic guided vehicle is stopped near the work position, the image detection means detects the mark. , a conversion formula is created based on the deviation between the mark position at this time and the mark position at the time of teaching, and the teaching point of the robot is corrected by this conversion formula. We have already proposed and applied for a position correction method. (Refer to Japanese Patent Application No. 61-34482.) According to the present invention, it is possible to correct the teaching point according to the position of the robot. The amount of deviation of the gripping portion is corrected by correction, and the orientation of the hand itself with respect to the workpiece is not subject to correction. For this reason, in the case of a robot that grips a workpiece, there is a problem that the orientation of the hand itself relative to the workpiece when gripping the workpiece during work may be different from that during teaching, which may impede handling. Ta.

This invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to correct not only the Nli of the handling position relative to the workpiece, but also the direction of the hand itself, so that the hand itself relative to the workpiece during work can be corrected. An object of the present invention is to provide a method for correcting the position of a robot mounted on an automatic guided vehicle, which can make the orientation of the robot the same as when it is taught.

"Means for solving the problem" This invention transports a robot mounted on an automatic guided vehicle to a work position, and performs work on a workpiece placed at the work position according to teaching points taught in advance. The automated guided vehicle-mounted robot includes a mark recorded at a predetermined location of the working position and an image detection means attached to the robot, and after stopping the automated guided vehicle near the working position, The mark is detected by the image detection means, and information defining the deviation m between the current mark position information and the mark position information at the time of teaching and the amount of deviation between the direction of the hand with respect to the workpiece at the time of teaching and the current direction of the hand is obtained. A conversion formula is created based on the conversion formula, and this conversion formula is used to correct the teaching point of the robot and the direction of the hand relative to the workpiece, thereby solving the above problems.

"Operation" According to the above configuration, the direction of the hand with respect to the workpiece is determined based on the amount of deviation between the current mark position and the mark position at the time of teaching, and the deviation m between the direction of the hand at the time of teaching and the current direction of the hand. can be easily corrected.

Therefore, the direction of the hand relative to the workpiece can be corrected and controlled so as to be the same as that at the time of teaching.

"Embodiments" Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view showing an embodiment of the present invention. The automated guided vehicle used in this example may be either a guided unmanned vehicle that runs along a guide line laid on the ground, or a so-called autonomous unmanned vehicle that runs without a guide line. .

The robot 2 is mounted on the automatic guided vehicle I. The robot 2 has an arm 3 that can rotate horizontally, rotate back and forth, and move up and down. The movable part 3 is located at the tip of the arm 3.
An image input device 4 and a hand 5 are integrally attached via a, and are configured to be capable of swinging and twisting motions. The image input device 4 is a solid-state image sensor made of a COD (charge coupled device) or the like. Further, the hand 5 is for gripping the workpiece 6. Note that the workpiece 6 is drawn enlarged compared to the robot 2. The workpiece 6 is placed in a frame 7a formed at the center of the upper surface of the workbench 7.
It is placed there and receives the work of robot 2. A mark 8 consisting of two points 8a and 8b is written on the corner of this workbench 7.

In such a configuration, the automatic guided vehicle 1 travels between the plurality of work platforms 7 and performs work. In this case, the stopping accuracy of the automatic guided vehicle l is low and the position must be corrected using the following procedure.

(1) First, when teaching is performed prior to work, the mark 8 is read and the work point is taught. That is, the image input device 4 is moved directly above the mark 8 and this position is taught, and the coordinate position of the mark 8 on the screen captured by the image input device is stored together with the work operation. In this case, for example, take a horizontal orthogonal coordinate system X-Y with the origin at the center of the bottom of the robot 2's legs and the X axis in a direction parallel to the horizontal scanning line of the image input device 4, and point 8a of the mark 8 in this coordinate system.
, 8b as (X a, Y a) and (xb, y
b) (Figure 2(a)).

(2) Next, consider a case where the automatic guided vehicle l moves toward the above-mentioned work point and stops. At the stop position, the robot operates according to the taught procedure, and the image input device images the mark 8. The positioning accuracy of automatic guided vehicles is generally low, and in this case, the position coordinates of the mark 8 in the X-Y coordinate system are the position coordinates of the points 8a and 8b (X a, Y a) memorized at the time of teaching in (1). , (Xb, Yb). In other words, the coordinates on the X and Y axes differ by the amount of positioning error of the unmanned guided vehicle l, and the
The -Y coordinate system is not shown in FIG. 2(a) and is shifted to the U-V coordinate system.

Therefore, the coordinates of the teaching point Pi taught in the X-Y coordinate system (X i.

Correct handling operation can be performed on the workpiece 6 by converting Yi) into the Teno coordinates (Ui, Vi) of the UV coordinate system.

This conversion method will be described below.

In the following description, the coordinates of the point 8a of the mark 8 in the UV coordinate system are (Ua, Va), and the coordinates of the point 8b are (ub, vb).

In such a setting, a conversion method will be described using the steps shown in FIGS. 2(b) to 2(d).

(+) With point 8a as the origin, X-Y parallel to the X-Y coordinate system
When finding the locus 11 (xi, yi) of the teaching point Pi in the coordinate system (see Figure 2, b), xi=X i -X a yi= Y i -Y
aIf this is expressed as a matrix, here Zi and zi are the coordinates in the height direction of the point Pi in each of the X, Ys, and Y coordinate systems, and these are unchanged. Here, it is assumed that the matrix defining the transformation between the X-Y coordinate system and the X-Y coordinate system is 8.

(2) Next, the coordinates of point 8b of mark 8 in the K-Y coordinate system are determined as shown in FIG. 2(b).

That is, from formula (1), (Xb-XaS Yb-Ya) is obtained.

Also, the coordinates of the point 8b rotated clockwise by Δ0 are (U
b-UaSVb-Va). This is point 8b in the coordinate system (this is nothing but the UV coordinate system, which will be described later), which is translated in parallel to the UV coordinate system and whose origin is (Ua, Va).
matches the coordinates of

The straight line connecting these two coordinates (Xb-Xa, Yb-Ya) and (Ub-Ua, b-Va) and the origin is
Letting the angles with the axis be α and β, Lana = (Y b - Y a)/ (X b -
X a) tan β wealth (vb-va)/(Ub-Ua)・
...(4) Also, from Δθ=β-α, tanΔθ=S/T, where S = (Xb-Xa) (Vb-Va) - (Y b - Y aXU b - U a) T = (X
b - Xa) (Ub - Ua) - (Y b - Y a) (
V b - V a) Therefore, Δθ = A rctans / T (3) If the new coordinate system when the x-y coordinate system is rotated by Δθ as shown in Figure 2 (c) is u-1v, then (
4) As shown in Figure 2(d), the uv coordinate system is parallel to 8
Move it to the U-V coordinate system, and place the point P in this coordinate system.
Coordinates of i (Ui, Vi)liUi=ui+Ua Vi=vi+Va From this, the transformation matrix is From the above, the coordinates of point Qi after transformation are Qi=C-B-
It can also be stopped with A-Pi.

In the case of a three-dimensional image, the marks may be set as three three-dimensionally independent points, and these points may be read by two or more human-powered image devices. Then, calculations similar to those in the two-dimensional case are performed. That is, a transformation formula may be determined based on the amount of parallel movement and the amount of inclination in each coordinate axis direction, and the coordinate transformation may be performed using these as well.

Next, the operation of this embodiment will be described.

First, at the time of first teaching, not only point A, which is the teaching point shown in FIG. 1, but also the position coordinates of the robot hand base (point B shown in FIG. 1) are stored. Then, during playback, the position of the teaching point B is corrected using the above-mentioned conversion means. Next, the position of the teaching point A of the robot hand gripping section is corrected.

In this way, the robot hand is corrected and positioned with respect to the workpiece using two points, so not only is the position of the handling point corrected when the robot hand grasps the workpiece, but also the position of the handling point is corrected when the robot hand grips the workpiece. It is possible to correct and define the direction of the robot hand in the same manner as when teaching.

In this example, there are two points on the robot hand:
That is, the position of the robot hand is corrected at the teaching point A1 on the gripping part and the teaching point B on the hand base, and as a result, the direction of the robot hand with respect to the workpiece is defined. Instead of points A and H, the teaching point B at the base of the hand is corrected in the same manner as in the above embodiment, and then the direction cosine is used to correct the direction of the hand, and the direction of the robot hand relative to the workpiece is corrected and controlled. You may also do so.

"Effects of the Invention" As explained above, according to the present invention, it is possible not only to correct the positional deviation of the hand that engages with the workpiece, but also to make the direction of the hand relative to the workpiece the same as when teaching. Effects can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view showing the configuration of an embodiment of the present invention;
FIG. 2 is a graph for explaining coordinate transformation.

Claims (1)

[Claims] Transport the robot mounted on the automated guided vehicle to the working position,
In a robot mounted on an automatic guided vehicle that performs work on a workpiece placed at the work position according to teaching points taught in advance, a mark recorded at a predetermined location at the work position and an image attached to the robot. detecting means, after stopping the automatic guided vehicle near the working position, detecting the mark with the image detecting means, and determining the amount of deviation between the current mark position information and the mark position information at the time of teaching, and the time of teaching. A conversion formula is created based on information that defines the amount of deviation between the direction of the hand with respect to the workpiece and the current direction of the hand, and the teaching point of the robot is corrected and the direction of the hand with respect to the workpiece is corrected using this conversion formula. A method for correcting the position of a robot mounted on an unmanned guided vehicle, characterized by: