JPS58206394A - Method of correcting position of robot - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for correcting the position of a robot, that is, a force method for correcting the position of a member (so-called work) held by the robot. In particular, it relates to the correction JJ method that can be suitably used when a force is applied to the workpiece [2, a deflection occurs between the robot's hand and the workpiece, causing a -C1 positional deviation.

In recent years, in order to automate the multi-glaze, small-stitch, cheek finishing II, a variety of tasks have been carried out. b-robot)? In order to use the robot effectively, it is important to have the robot perform a wide variety of tasks, and for this purpose, a single robot can grasp a variety of parts11, process and assemble them, etc. In recent years, automatic exchange devices have been developed.

However, these nodes, automatic node exchange devices, etc.
If you attach it to the r2 pot hand, its total length will be long.
Furthermore, when gripping and positioning objects that have frictional resistance or parts/tools that are subject to restraining force, the deflection of these parts when an external force is applied to the parts is large, and it is difficult to determine the position of the robot's hand. A problem arises in that a deviation occurs between the position of the warp, ignoring the deflection "fr" caused by i, and the actual position.

For this reason, conventional methods have been used to determine the position of the robot's hand using a feeding box, etc., to determine the workpiece position using the robot's hand under actual load conditions, and to teach the position based on this information. .

This method has no problem because the deflection is small (or constant) when the external force acting on the workpiece is small or constant, such as gravity, but if the external force in the horizontal direction fluctuates, the deflection will not be constant. This is a problem. In other words, as shown in Fig. 1, when moving the workpiece and tool @=4 5 turns υ on the axis south of the stamping resistance, the acceleration/deceleration conditions during movement of the workpiece at that time, the inertia of the workpiece, etc. In the teaching method described above, even if the position of the hand of the robot 1 is reproduced with high accuracy, there arises a problem that the position of the workpiece varies more than that as shown in FIG. In the end, the workpiece could not be positioned with high precision, which was a factor that lowered the success rate of the assembly worker's work. In addition, if we tried to solve this problem (7), it would have been difficult to install an additional 1q correction device, which would have made it difficult to increase the price of automated e-equipment.

An object of the present invention is to eliminate the drawbacks of the above-mentioned prior art, and to reliably and easily compensate for the buffiness of the workpiece position 1a caused by the deflection of the workpiece. There is an IC that has proposed a method for correcting the position of a robot that also contributes to reducing the amount of damage.

In the present invention, a force detection device is installed between the robot's hand and the workpiece, thereby determining the force acting on the workpiece, and from this, determining the deflection Iir between the robot's hand and the workpiece. Hand position
fi (takes a configuration that corrects f. With a configuration like jin,
In any case, it is possible to reliably and easily position the workpiece at a predetermined position.

Hereinafter, one embodiment of the present invention will be described based on FIG. The illustrated embodiment shows a hand portion of a robot to which the method of the present invention is applied. In this example, as shown in FIG. 6, a force detection device 10 is attached to the hand of a robot. The force detector 10 of this example detects force in the horizontal direction. That is, the present invention is applied to a system comprising a robot arm 7, a horizontal force detection device 10 attached to the tip 2 of this arm, and a hand 3 attached to this force detection device 10. This force detector (flo is a beam-shaped detection part 6
This beam has a rectangular cross section, and the force is detected and obtained from the deflection of the surface 8 corresponding to the long side of the rectangle. Since the horizontal force is detected here, the surface 8 is located in the vertical direction, and the horizontal force is easy to detect, but the vertical IM direction force is not detected due to its high rigidity. . Note that the rectangular cross section here refers to the cross section of the beam-shaped detection unit 6 viewed in the axial direction of the arm 7, that is,
It refers to the surface corresponding to the Tamen line cross section.

Next, the operation of this embodiment will be described using FIG. 4.

First, it will be explained that the horizontal force detection device 10 can determine the deviation t of the workpiece position from the robot hand position. In FIG. 4, a point Pe is the center position of the assembly of the robot 4, and a point O is the hand position of the robot. Parts A, H, C
', l) are respectively work 4. Hand 3. Horizontal force detection &W1u, a represents bond arm 7.

The length of these members kti + the second moment of area is lL
, the section modulus is ll, and the longitudinal elastic modulus is A! (t = A.

B, (,", l) ), and the external force acting on point P is F. If we consider that point O is fixed, then the point P is bent as follows: It can be determined as the sum of the deflections of the individual members caused by

That is, member C is dy'cFx F(L)+lB+xc)dr(H=
Shoulder=-7CI ``'''(') The deflection '/c and slope y'c of the torso side end of section 19 are yc=fff (xc
)dxc+y'c=ff (xc)cLxc
Therefore, similarly for [7 side II, A'/"5-17 (xB)tLxH F, x y A=fif r x4) tt, x, l where f'-4>= Eiy'A = ff(xA)dxi, and by calculating these deflections and inclinations by correcting h[, the position of point P with respect to point O can be found.Here, the only unknown quantity is F, and since the others are known, the position of point P of member C Attach the strain gauge 11 to the point Q and find the position of the point P by finding -(F-f. That is, when the strain ε at the point Q is found by the strain gauge, σQ-ε・Ec=z ,”=””Q/l(from F:ε@h
c*Zc/,.

is found. Therefore, since F is known υ, the position of point P can be found. The member C has a rectangular cross section as described above, and the strain gauge 11 is attached to the long side face 8, and the long side face 8 is vertical, so that the force in the horizontal direction is easy to check, and the force in the direction of the image is determined by the stiffness. It is necessary to raise the temperature so that it is not detected.

If the force detection device 12 is made of the member Ct-parallel leaf spring structure as shown in FIG. 5, the correction of the neck of the members C' and BfJJ can be eliminated and the opening 1n can be simplified.

This force detector 12 has a structure in which two beams 91 and 92 each having a rectangular cross section are combined in parallel.

Note that here, the deflection t of the robot arm l (member D)
Although the explanation has been made assuming that the robot arm 7 does not deflect, the above-mentioned turbidity can be applied, and the deflection t of the robot arm 7 can be calculated based on F obtained from the force detection device 10. The position of point P can be corrected by calculation.

In the above explanation, correction of positional deviation in the horizontal direction was described, but based on exactly the same idea, it is possible to correct positional deviation in the Taruyama direction, etc. by installing a device that detects force in a fixed direction. It goes without saying.

In addition, in this explanation, the assembly position P of the workpiece is determined and corrected with the U-bot hand position, but by using a force detection device, the external force at the time of teaching is determined, and the same force as that external force is applied at the time of positioning. '', it goes without saying that the position can be corrected to the state where it is.

As described above, a force detection device is attached to the robot's hand, and the deviation between the robot's hand position (reference position) and the gripped workpiece position l11 (position required for assembly) is determined using this device. Since the position can be corrected, variations in the position of the workpiece caused by deflection of the member can be reduced, and positioning accuracy can be improved.

“It also has economical effects, such as eliminating the need for a positional deviation correction device that was previously required.

It should be noted that, as a matter of course, the present invention is not limited to the illustrated embodiment.

[Brief explanation of drawings]

FIG. 1 is a 100-sided diagram showing a prior art device in which a workpiece is gripped (7). FIG. 2 is an explanatory diagram showing that variations in workpiece position occur in the device of FIG. 1. Fig. 3 is a perspective view of one embodiment of the present invention, Fig. 4 is an explanatory diagram showing that the workpiece position to be corrected is determined by the force detection device in a fundamental manner. Fig. 5 is a perspective view of an embodiment of the present invention. It is a perspective view of an example of 1... robot 2... arm tip 4.
...Parts (work) 7...Robot arms 6, 9
1.92...Detection part (beam) 10.12...Force detection device representative patent attorney Usui 1) Toshiyuki 1st 3rd figure 4 Figure, ---1 Kiku 5 Figure 7,

Claims (1)

[Claims] 1. A force detection device [attached to the tip of the arm of the robot;
A method for correcting the position of a robot, characterized in that the force acting on the member held by the robot and the deflection caused by the force are determined by the force detection device, and the position of the member held by the robot is corrected based on the force acting on the member held by the robot. 2. The force detection device includes a detection section having a beam with a rectangular cross section, and the detection section has a structure capable of detecting force from the deflection of a surface corresponding to the long side of the beam. A method for correcting the position of a robot according to claim 1. 3. The robot position correction method according to claim 2, wherein the detection section of the force detection device is constructed by combining two parallel beams with a rectangular cross section.