JPH06143166A - Method for correcting displacement in position of articulated robot - Google Patents

Abstract

PURPOSE:To provide a method through which displacement in a position is simply corrected without teaching again even when permanent deformation is left at each joint as a result of an articulated robot being brought into erroneous collision with a work. CONSTITUTION:A reference plate 14 is attached to the tip of an articulated robot and displacement sensors 5, 6, and 7 and industrial cameras 8 and 9 are mounted in the vicinity of the work region of the articulated robot when the articulated robot is brought into a reference posture. By detecting the position posture of the reference plate 14, a new reference origin is set.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a displacement correction method for an articulated robot, and is improved so that the displacement can be corrected particularly easily.

[0002]

2. Description of the Related Art A large amount of industrial robots have been introduced into the industrial world, which has made it possible to improve the efficiency of a high-mix low-volume production system and free it from heavy labor work. FIG. 1 shows an articulated robot 1 which is a type of industrial robot and its controller 2.

This multi-joint robot 1 has six joints 1.
a, 1b, 1c, 1d, 1e, 1f, which has six degrees of freedom, and has six movements: body rotation a, upper arm tilt b, forearm tilt c, wrist up / down bending d, wrist rotation e, and holding part drive f. I do.

When teaching the articulated robot 1, the articulated robot may collide with a work due to carelessness or error. In addition, if there is a dimensional defect of the work during playback work, the articulated robot 1
May collide with the work.

When the articulated robot 1 collides with the work in this way, the gears and arms of the joints are permanently deformed and the positions of the arms are displaced, so that the teaching program including an error from the teaching point cannot be used. In order to deal with such a situation, conventionally, the following two measures have been taken.

(I) When the number of programs is small, teaching is performed again to create a new teaching program, and a playback operation is performed using this new teaching program.

(Ii) When the number of programs is large, the deviation amounts of the joints 1a to 1f are accurately measured by various methods, and the joint angle parameters are corrected by the measured amount to correct all programs. I do.

[0008]

However, the method (i) described above is troublesome because the teaching must be performed again, while the method (ii) accurately measures the deviation angle of the joint angle. Since it is difficult to correct the program, there is also a problem that the program cannot be corrected accurately, and that there is no extra space for installing the measuring device in the actual manufacturing line.

The present invention has been made in view of the above prior art, and an object of the present invention is to attach a reference plate to an articulated robot to correct the displacement before and after the collision of the articulated robot.

[0010]

The configuration of the present invention which achieves such an object is used when operating each joint according to a program with each joint of each joint when the articulated robot is in the reference posture as a reference origin. In the misregistration correction method,

A correction device equipped with a plurality of displacement sensors and an industrial camera (ITV camera) is installed near the work area of the articulated robot, and a reference point such as a hole or a corner is provided at the tip of the articulated robot. Attached reference plate,
The articulated robot is moved so as to face the correction device, and the joint angle of each joint at this time, the output of the displacement sensor, and the reference point coordinates in the industrial camera are recorded. Make sure that the reference plate does not come off the displacement sensor and that the reference point does not come off the industrial camera.

After that, when a permanent displacement occurs in each joint due to impact or the like on the articulated robot, the reference plate attached to the tip of the articulated robot and the correction device are in the same state as described above. The multi-joint robot is moved so as to face each other, and at this time, the output of the displacement sensor and the coordinate in the industrial camera, which are recorded in advance, are moved to be equal. When the output of the displacement sensor and the reference point coordinates in the industrial camera become equal, the difference between each joint and the joint angle recorded in advance is calculated, and the reference origin of each joint is set by the calculated difference. It is characterized by shifting.

[0013]

Embodiments will be described in detail below with reference to the embodiments shown in the drawings. As shown in FIG. 1, the articulated robot 1 has one basic posture defined, and the joint angles of the joints 1a to 1f when this basic posture is taken are used as reference origins in accordance with the program to joints 1a to 1f. If is activated.

On the other hand, as shown in FIG. 2, a conveyor 3 that conveys a work is arranged in front of the multi-joint robot 1, and the work area A is directly in front of the multi-joint robot 1. Next to the work area A, the correction device 4 is fixedly installed above the conveyor 3 at a position where it does not interfere with the conveyance of the work. The position of the correction device 4 does not change even if the work is conveyed by the conveyor 3.

As shown in FIG. 3, the correction device 4 includes three displacement sensors 5, 6, 7, two industrial cameras 8, 9, an image processing unit 10, a displacement measuring unit 11, and an information processing unit 12. And a display 13. On the other hand, a reference plate 14 shown in FIG. 4 is attached to the tip of the articulated robot 1. The reference plate 14 has two reference holes 15 and 16 as reference points.

The reference plate 14 includes three displacement sensors 5,
4, 6 and 7 are moved by the articulated robot so as to face each other as shown in FIG. 4, and at this time, the two industrial cameras 8 and 9 face the reference holes 15 and 16 of the reference plate 14, respectively. Become. It should be noted that three or more displacement sensors are required for plane recognition, and two industrial cameras are generally provided to capture two reference points on the reference plate. When two reference points are included in the field of view of one camera, one industrial camera may be used.

Further, instead of the reference holes 15 and 16, LEDs are used.
An invariant one such as a light or a corner of a reference plate may be used. In the case of the reference holes 15 and 16, the center of gravity of the holes is treated as the reference point.

Regarding the correction method by the correction device 4,
Explain along the work procedure. Each joint angle when the articulated robot 1 is in the reference posture
Is predetermined. That is, each joint 1 serving as the reference origin
The joint angles of a, 1b, 1c, 1d, 1e, 1f are θ _a01，
θ_b01, Θ_c01, Θ_d01, Θ_e01, Θ_f01Has become. Attach the reference plate 14 to the tip of the articulated robot 1.
It In this state, inching operation of the articulated robot 1 is performed.
Then, the reference plate 14 faces the correction device 4. At this time,
The quasi plate 14 does not come out of the measurement area of the displacement sensors 5 to 7.
Similarly, the reference holes 15 and 16 are similar to the industrial camera 8 and
Make sure you stay within the 9's field of view.

As described above, when the reference plate 14 and the correction device 4 face each other, the joints 1a, 1b, 1c, 1d, 1e, 1f displayed on the display surface 2a of the controller 2 are shown.
Joint angles θ _a11 , θ _b11 , θ _c11 , θ _d11 , θ _e11 , θ
_f11 , output values of displacement sensors 5 to 7, industrial camera 8,
Record the coordinates of the reference point on the 9 field of view. When the recording is completed, the reference plate 14 is attached to the articulated robot 1.
Remove from and perform teaching and actual work.

When a shock is applied to the multi-joint robot 1 during teaching or actual work and the joint is permanently deformed, the reference plate 14 is attached to the multi-joint robot 1 again.
Then, the reference plate 14 and the correction device 4 are made to face each other in the same manner as. After that, the articulated robot 1 is operated by inching so that the output values of the displacement sensors 5 to 7 and the reference point coordinates of the industrial cameras 8 and 9 match the values recorded in.
When they match, the joint angles θ _a12 , θ _b12 , θ _c12 , θ _d12 , θ _e12 , and θ _f12 displayed on the display surface 2a are recorded. Then, as shown in the following formula, the difference between this joint angle and the joint angle before the collision is obtained.

Δθ _a = θ _a12 −θ _a11 Δθ _b = θ _b12 −θ _b11 Δθ _c = θ _c12 −θ _c11 Δθ _d = θ _d12 −θ _d11 Δθ _e = θ _e12 −θ _e11 Δθ _f = θ _f12 −θ _f11

Then, as described below, the reference origin of each joint is shifted by the above angle difference. θ _a01 → θ _a01 + Δθ _a = θ _a02 θ _b01 → θ _b01 + _Δ θ _b = θ _b02 θ _c01 → θ _c01 + Δθ _c = θ _c02 θ _d01 → θ _d01 + Δθ _d = θ _d02 θ _e01 → θ _e01 + Δθ _e = θ _{e02 θ f01 → θ f01 + Δθ f} = θ f02

[0023] After that, the joint angle theta _a02 determined in this _{way, θ b02, θ c02, θ} d02, θ e0 2, the theta _f02 as a new reference origin, executes the program. In this case, since the deformation of the articulated robot 1 is compensated by changing the reference origin of the program, the desired machining can be executed without changing the program.

In the above-mentioned embodiment, the articulated robot having 6 degrees of freedom is corrected, but the present invention can be similarly applied to the articulated robot having other types of degrees of freedom. Is.

[0025]

As described above in detail with reference to the embodiments, the present invention has the following effects. (1) Since the deformation of the articulated robot is compensated by shifting the reference origin, it is not necessary to change the program. (2) Since a non-contact measuring device such as a displacement sensor or an industrial camera is used to eliminate the intervention of the operator's intention, it is possible to avoid the correction error due to the individual difference of the operator. (3) Since the correction work is performed at a position close to the work area, there is almost no deviation in the work area.

[Brief description of drawings]

FIG. 1 is a perspective view showing an articulated robot.

FIG. 2 is a plan view showing an arrangement of an articulated robot.

FIG. 3 is a conceptual diagram showing a configuration of a correction device.

FIG. 4 is a perspective view of a reference plate.

[Explanation of symbols]

 1a, 1b, 1c, 1d, 1e, 1f Joints 2 Controller 3 Conveyor 4 Correction device 5, 6, 7 Displacement sensor 8, 9 Industrial camera 10 Image processing unit 11 Displacement measurement unit 12 Information processing unit 13 Display 14 Reference plate

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location // B25J 9/06 A 8611-3F

Claims (1)

[Claims] 1. A displacement correction method used when operating each joint according to a program, using each joint angle as a reference origin when the articulated robot is in a reference posture, and a plurality of displacements near a work area of the articulated robot. A correction device including a sensor, an industrial camera, and an image processing device is arranged, and a reference plate is attached to the tip of the articulated robot, and the joint angle of each joint angle when the reference plate is faced to the correction device, The output of the displacement sensor and the coordinates of two or more reference points in the field of view of the industrial camera are recorded in advance, and then, if a position shift occurs during the operation of the articulated robot, the articulated robot The multi-joint robot is moved so that the reference plate attached to the end of the joint faces the correction device, and the difference between the joint angle of each joint at this time and the joint angle obtained in advance is calculated. A method for correcting misalignment of a multi-joint robot, characterized in that the reference origin of each joint is shifted by this difference.