JPS6353608A - Industrial robot - Google Patents

Abstract

PURPOSE:To execute the highly accurate work with a simple device by counting a deviation quantity from a work position from the rotation angle of one point of an arm when a non-contacting type sensor detects a worked position and thus, correcting work information. CONSTITUTION:An industrial robot 12, when car body parts 11 are conveyed, drives an arm 13 so that an optical axis generated by an optical fiber sensor 27 can be vertical to panels 11a and 11b and detects an overlapping part 14 of the panels 11a and 11b. Then, the rotation angle theta of a second joint 18 is detected from the signal of an encoder 23. A control device 25 counts a deviation quantity (t) from the work position of the overlapping part 14 with a data table from the rotation angle theta and this corrects a welding work program. The data table adopts the correlation of the rotation angle theta and the deviation quantity (t) measured by the standard car body parts beforehand. Thereafter, since the panels 11a and 11b of the parts 11 are welded with a torch 26 in accordance with a corrected welding program, it is welded with a high accuracy.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a teaching playback type industrial robot that performs work by reproducing previously taught motions, and more particularly relates to a teaching playback type industrial robot that performs work by reproducing previously taught motions. The present invention relates to an industrial robot that detects a positional deviation of a robot and corrects a reproduction operation based on the positional deviation.

(Prior Art) A teaching playback type industrial robot stores a series of work information as a program in a storage device, and a work object (hereinafter referred to as a work) that is sequentially transported to a predetermined work position according to the program. Perform the same task repeatedly. Such industrial robots have high operational reliability and are capable of highly accurate machining of workpieces of the same shape located at predetermined working positions.

However, in the general manufacturing process, the dimensions of the workpiece are allowed to have dimensional tolerances and the dimensions of the workpiece are slightly different, and it is difficult to accurately position the workpiece at a predetermined working position. There is a drawback in that the parts deviate from the predetermined working positions, making it impossible to process the workpiece with high precision even with the above-mentioned robot. Particularly in the manufacturing process of automobile bodies, the workpieces are large and the dimensional tolerances are large, so the drawbacks are significant.

As a countermeasure to these shortcomings, industrial robots have been put into practical use that use contact sensors such as limit switches to detect the part of the workpiece to be worked on and compensate for deviations. There are other problems, such as low reliability of detection due to constraints such as shape, etc., and complicated movement of the arm to bring the sensor into uniform contact during detection.

Therefore, in such industrial robots, it is desirable to recognize the object to be worked on using a non-contact sensor such as a visual sensor and compensate for the deviation of the workpiece part from the working position. Compensation for deviations using such a non-contact sensor has been carried out by reusing, for example, the technique of a pattern inspection apparatus described in Japanese Patent Publication No. 56-51387.

This pattern inspection device processes an image signal of a two-dimensional pattern in time series using an image pickup device, and locally compares the signal with a reference pattern signal to inspect for defects.

(Problem to be solved by this invention) However,
In the pattern inspection device described in the above-mentioned Japanese Patent Publication No. 56-51387, an imaging device is essential and the entire device is large, and the processing of the signal is also complicated, so it is desirable to simplify the 4W configuration. This cannot be applied to industrial robots. In particular, when industrial robots process automobile body parts, it is known from experience that the position of the workpiece to be worked on is unevenly distributed in one direction. Applying a pattern inspection device only increases the cost of the device, and the practical effect cannot be expected compared to the cost incurred.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an industrial robot with a simple configuration and low cost that can reliably compensate for the deviation of the workpiece part from the working position.

(Means for Solving the Problems) As shown in FIG.
A point a is equipped with a work tool B at the tip of a rotatable arm A, and a point a is provided with a work tool B at the tip of a rotatable arm A. In an industrial robot that repeatedly performs the same work, a work part sensor C is provided on the arm A and is capable of detecting a work part W of the work object W in a non-contact manner as the arm A rotates; An angle sensor D that detects the rotation angle of the arm A at a predetermined point a when the part sensor C detects the work part W of the work object W, and an angle sensor D based on the output signal of the angle sensor D. a deviation calculation means E that calculates an amount of deviation of the work area W of the work object W in one direction from the work position, and the work information is calculated based on the deviation amount calculated by the deviation calculation means e. It is characterized by comprising a correction means F for correction.

(Function) According to the industrial robot according to the present invention, the non-contact type work part sensor detects the work part of the work object by rotating the arm, and the work part sensor detects the work part. The amount of deviation of the part to be worked in one direction from the working position is calculated based on the rotation angle of one predetermined point of the arm when the arm is rotated, and the work information is corrected based on this amount of deviation. Therefore, the amount of deviation can be reliably detected without being restricted by the shape of the object to be worked on, allowing the industrial robot to perform work with high precision. Since only the amount of deviation in one direction is detected based on the rotation angle at one point on the arm, a simple optical sensor or ultrasonic sensor can be used as the work area sensor, and subsequent signal processing becomes complicated. This makes it possible to simplify the overall configuration and reduce costs.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIGS. 2 and 3 show an industrial robot according to an embodiment of the present invention, with FIG. 2 being an overall view and FIG. 3 being a block diagram.

In Figure 2, (11) is divided into two panels (lla) (
car body parts (object to be worked on) having
(12) is an industrial robot equipped with a swingable arm (13). The vehicle body part (11) is a panel (lla
) (llb) (worked part) (14) is welded by an industrial robot (12) to join the panels (11a) (1lb) together. The arm (13) of the industrial robot (12) includes a first member (17) rotatably connected to the base (15) via a first joint (1B), and a first member (17) connected to the first member (17). A second member (19) rotatably connected via a second joint (18), and a hand rotatably connected to the second arm member (19) via a third joint (20). (
21). 1st Jyoin) (1,
6), second joint (18) and third joint (
20) have these joins) (1B) (1
8) a pulse motor (not shown) that drives (20);
Encoder for detecting rotation angle of joint (1B) (18) (20) (angle sensor (22) (23) (24)
is provided. The pulse motor is connected to a control device (25) and rotates according to a drive pulse signal inputted from the control device (25), and also has an encoder (22) (2
3) (24) is connected to a control device (25) and rotates the pulse motor in response to a drive pulse signal output from the control device (25) to the pulse motor (join) (
1B) Outputs a digital signal indicating the rotation of (18) and (20).

The hand (21) has a panel (ll) of the car body part (11).
a) A MIG welding machine torch (213) for welding (llb) is provided, and a panel (lla)
An optical fiber sensor (work site sensor) (27) that non-contact detects the overlapping portion (14) of (llb) is arranged in parallel with the torch (26). Optical fiber sensor (27)
is connected to the control device (25) to emit and receive light, and the intensity of the received reflected light, that is, the panel (lla) (
The control device (25) sends a voltage signal according to the distance to
Output to.

This optical fiber sensor (25) has a panel (lla) (
llb) is detected by the intensity of reflected light.

The control device (25) has, as shown in FIG. 3, a well-known computer (28) consisting of an input/output interface (Ilo), a memory (M) and a central processing unit (CPU). This computer (
The pulse motor and encoders (22), (23), and (24) are connected to the drive circuit (28), and the optical fiber sensor (27) is connected to the A/D converter (30). The encoder (22
), (23), and (24) are connected to a counter (31) that counts the digital signals output from the terminals. This computer (28) is connected to an external storage device (not shown), and this storage device stores a welding work program (work information), a program for detecting the amount of deviation, a data table for searching the amount of deviation, etc. has been done. This computer (2
8) corresponds to a deviation calculation means and a correction means.

Next, the operation of this embodiment will be explained.

In this industrial robot (12), when a vehicle body part (11) is conveyed by a conveyor or the like, the optical axis of the light emitted by the optical fiber sensor (27) is aligned with the panel (lla) (+
The overlapping portion (14) of the panels (lla) (Ilb) is detected by driving the arm (13) perpendicularly to the optical fiber sensor (27) by changing the output potential of the optical fiber sensor (27). When the output potential of the sensor (27) changes, the rotation angle of the second join 1-(1B) is 0, that is, the member (
17) Detect the rotation angle θ of (19) from the output signal of the counter (31) that counts the digital signal of the encoder (23). Then, the computer (28) calculates this rotation angle θ
Based on the above data table, the amount of deviation t of the overlapping portion (14) from the working position in one direction is calculated, and based on this amount of deviation, the welding work program is corrected only for the one direction in which the welding work program is deviated. In addition, the above data table is based on rotation O measured in advance using standard vehicle body parts (11).
The correlation between the amount of deviation and the amount of deviation t is adopted.

Thereafter, the industrial robot (12) uses the torch (13) of the arm (13) according to the corrected welding work program.
26) Panel (l la) of car body part (11)
Weld (llb). Therefore, car body parts (11)
Even if the panels (11a) (1lb) are displaced from the working position, these panels (lla) (llb) will be welded with high precision.

(Effects of the Invention) As explained above, according to the industrial robot according to the present invention, when the arm is rotated and the non-contact sensor detects the work area of the work object, one point on the arm The amount of deviation of the part to be worked from the working position is calculated based on the rotation angle, and the work information is corrected based on the amount of deviation. Therefore, highly accurate work can be performed without increasing the size of the entire device and without complicating signal processing.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an industrial robot according to the present invention. 2 and 3 show an industrial robot according to an embodiment of the present invention, with FIG. 2 being an overall schematic diagram and FIG. 3 being a block diagram. 11... Vehicle body parts (work object W) 12... Industrial robot 13... Arm A 14... Overlapping part (worked part W) 18... Second
Joint (rotation point a) 23...Encoder (angle sensor D) 25...Control device 26...Torch (work tool B)

Claims (1)

[Scope of Claims] A working tool is provided at the tip of an arm that is rotatable at least at one point in the middle, and the work tool is provided at the tip of an arm that is rotatable at least one point in the middle, and the work tool is installed at a work site of a work object located at a predetermined work position based on work information taught in advance. In an industrial robot that repeatedly performs the same work using the work tool, the work part sensor is provided on the arm and is capable of detecting a work part of the work object in a non-contact manner as the arm rotates; an angle sensor that detects a rotation angle at a predetermined point of the arm when the sensor detects the work area of the work object; It is characterized by comprising: a deviation calculation means for calculating the amount of deviation of the part from the work position in one direction; and a correction means for correcting the work information based on the deviation amount calculated by the deviation calculation means. industrial robot.