JPS5997873A - Method of correcting positional displacement of work in 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 [Technical Field of the Invention] The present invention relates to a method for correcting positional deviation of a workpiece in a robot.

[Technical background of the invention and its problems]

In a robot having a two-axis articulated arm that can be controlled by orthogonal coordinates, a workpiece, such as an operation panel, is carried to a predetermined position on the inspection table, and the inspection is performed based on predetermined reference orthogonal coordinates for the inspection table. The arm is rotated so that the inspection mechanism at the tip of the arm is located on the taught coordinates corresponding to the position of the object to be inspected, such as a switch or key, on the workpiece on the table.

In such a robot, in order to accurately position the tip of the arm over the object to be inspected on the inspection table, the workpiece must be set accurately at a predetermined position on the inspection table without shifting. must have been done.

For this reason, in the past, a suitable jig was used to place the workpiece at a predetermined position on the inspection table.

However, in order to use such a jig, it is necessary to provide a mechanism for operating the jig each time each work is carried onto the inspection table.

Furthermore, it is difficult to place large workpieces such as carriages and dispensers at predetermined positions on the inspection table using jigs.

On the other hand, if the above-mentioned jig is not used and the workpiece carried onto the inspection table is not in the specified position, that is, if the position is shifted, the workpiece on the inspection table should not be moved and the arm can be moved. There are ways to correct the movement. To do this, the position of the workpiece on the inspection table can be measured using a visual recognition mechanism such as a camera and its data processing device, and the movement of the robot's arm can be corrected based on the measurement results. it is conceivable that. However, in this method,
requires the use of expensive visual recognition mechanisms, and
There are restrictions on its mounting position.

[Purpose of the invention]

The present invention was made based on the above circumstances, and
The present invention aims to provide a method for correcting positional deviation of a workpiece in a robot, which allows the tip of an arm to be accurately positioned on a predetermined position on the workpiece without using a jig, a camera, or the like.

[Summary of the invention]

The present invention detects both end positions of the workpiece on the X-axis of the reference orthogonal coordinates and one end position of the workpiece on the X-axis of the coordinates using a sensor provided at the tip of the articulated arm between the two axes. The reference point of the workpiece is calculated based on the signal and the signal from the arm tip position detection means, and the reference point of the workpiece is moved in the X-axis direction and the Y-axis direction from the reference position on the coordinates based on the three position calculation values. Calculating the shifted distance and the angle at which the workpiece rotated from the reference position on the coordinates, and based on the calculated value of the distance and the calculated value of the angle,
The present invention is characterized in that the method for correcting positional deviation of a workpiece in a robot changes the value of the taught coordinate in the relational expression between the rotation angle of each axis of the arm and the coordinate.

[Embodiments of the invention]

FIG. 1 is a diagram showing the relationship between a two-axis articulated arm that can be controlled by orthogonal coordinates and a workpiece on an inspection table in a robot according to the present invention, and FIG. 2 is a block diagram of the control device of the robot. Figure 3 is a diagram showing the tip of the arm of the robot.

As shown in FIG. 1, 1 is a workpiece placed on a robot inspection table, and 2 is an arm of the robot.

The arm 2 consists of a first arm 2a and a second arm 2b.

As shown in FIG. 3, the head 3 at the tip of the first arm 2a is provided with a manipulator 4 for inspecting the workpiece 1, and a non-contact type manipulator 4 for detecting the end of the workpiece is provided surrounding the manipulator 4. A magnetic sensor 5 is provided. The head 3 is aligned with a plane (reference orthogonal coordinate plane) on the inspection table so that the workpiece 1 on the inspection table can be inspected and, as will be described later, the edge of the workpiece 1 can be accurately detected. Go up and down in orthogonal directions.

As shown in FIG. 1, the base end of the first arm 2a and the tip of the second arm 2b are connected via the first motor 6, and the second
The base end of the arm 2b is connected to the robot body via a second motor 7. The first arm 2a is rotated by the drive of the first motor 6, and the second arm 2b is rotated by the drive of the second motor 7. Thus, the manipulator 4 at the tip of the first arm 2a can be moved to the reference orthogonal coordinates of the examination table. It is possible to locate on arbitrary (taught) coordinates in .

As shown in FIG. 2, 8 is an arithmetic processing unit, 9 is a first servo interface, 10 is a second servo interface,
11 is a first driver for driving the first motor 6;
2 is a second driver for driving the second motor 7. The first motor 6 is connected via a first servo interface 9 and a first driver 11, and the second motor 7 is connected to
Second servo interface 10 and second driver 12
The respective drives are controlled by the arithmetic processing unit 8 via the arithmetic processing unit 8. The arithmetic processing unit 8 calculates the reference orthogonal coordinates of the examination table as (x, y) and the rotation angle of the first arm 2a as θ.
A patent that features the rotation angle of arm 2b and the following coordinate transformation formulas (1) and (2) θ1=f (x+y) ・・・・・・・・・・・・
... (1) θ2 = g (x, y) ...
...Based on (2), the first arm 2a and the second
Rotate arm 2b by 01 and θ2, respectively,
Position the tip of the first arm 2a on the taught coordinates (x, y). Therefore, when the workpiece 1 is correctly placed at a predetermined position on the inspection table, the tip of the first arm 2a is The manipulator 4 of the part can be accurately positioned on the workpiece 1 to be inspected.

As shown in FIG. 2, the output signal from the magnetic sensor 5 is input to the arithmetic processing unit 8 via the third servo interface 13. The two motors 6 and 7 have a first
An encoder 14 and a second encoder 15 are each attached. The first encoder 14 detects the rotation angle and direction of the first arm 2a, and the second encoder 15 detects the rotation angle and direction of the second deme 2b. The output signal from the first encoder 14 is input to the first amplifier down counter 16, and the deviation (number of pulses) from the reference value in the reference orthogonal coordinates is counted there. Similarly, the output signal from the second encoder 15 is input to the second up-down counter 17, and the deviation (number of pulses) from the reference value in the reference orthogonal coordinates is counted there.

The output signals from the two counters 16 and 17 are the first
, are input to the arithmetic processing unit 8 via the second servo interfaces 9 and 10, and based on these signals, the position ( coordinates) are calculated by the processing unit 8.

As shown in FIG. 1, before the workpiece 1 placed on the inspection table is inspected by the manipulator 4, the following operations are performed (in FIG. 1 indicates a workpiece placed at a predetermined position on the inspection table, and the solid line code 1 indicates a workpiece placed on the inspection table shifted from the predetermined position. (performed for work 1).

■) Move the first arm 2a and the second arm 2b,
The magnetic sensor 5 scans along the X-axis and the Y-axis of the reference orthogonal coordinates, and detects both ends of the workpiece 10 on the X-axis and one end of the workpiece 1 on the Y-axis.

2) Based on the output signal from the magnetic sensor 5 and the output signals from the first and second up/down counters 16 and 17, the positions of both ends of the workpiece 1 (XI, The one end position (yl) of the workpiece 1 on the axis is calculated by the processing unit 8.

3) As a result of 2), the width t (reading value) of workpiece 1 and the angle α (reading value) between the antiparallel and the side of workpiece 1 (see Figure 1)
As shown in Fig. 1, the workpiece 10 reference point a is
Reference position b in reference orthogonal coordinates (a+b is workpiece 1
Distance △X shifted in the X-axis direction (+) from (matches when the is placed on a predetermined position on the examination table), and a distance Δy similarly shifted in the Y-axis direction (+), The processing unit 8 calculates the angle θ by which the workpiece 1 is rotated from the reference position (the position indicated by the chain line in FIG. 1) on the reference orthogonal coordinates based on the following equations (8), (4), and (5).

jan (α-θ) 10D ・・・・・・・・・・・・(4)
4) Using △X, △y, and θ obtained in this way,
Corresponds to the teaching coordinates (x, y) when the workpiece 1 is placed at a fixed position on the reference orthogonal coordinates with respect to the workpiece 1 placed at a position shifted on the inspection table (solid line position in Figure 1) The corrected taught coordinates (x'+y) are calculated using the following formula (6
) is calculated by the calculation processing unit 8.

5) Corrected taught coordinates (X' obtained in 4).

y') to the coordinate transformation formulas (1) and (2) described above, (
x, y), and the arithmetic processing unit 8 calculates θ1 and θ2.

Therefore, by performing the above 1) to 5) prior to the inspection by the manipulator 4, the 17th
- The tip of the arm 2a can be accurately positioned.

Although the above description has been made regarding a two-axis articulated arm, the present invention can also be applied to a robot having an arm with three or more axes by increasing the number of measurement points of the sensor relative to the end of the workpiece.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to correct the positional shift of the workpiece on the inspection table without moving the workpiece, and the tip of the arm can be corrected without moving the workpiece. can be accurately positioned on a predetermined position.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the relationship between the arm of the robot according to the present invention and the workpiece on the inspection table, Fig. 2 is a block diagram of the control device of the robot, and Fig. 3 shows the tip of the arm of the robot. It is a diagram. 1...Work, 2...Arm, 2a...
・First arm, 2b... Second arm, 5... Magnetic sensor, 8... Arithmetic processing unit, 9, 11.1
3... pointer ace, 10.12... driver, 14.15... encoder, 16.17... up/down counter Application agent Patent attorney Kikuchi Part 5 Part 2 Figure

Claims (1)

[Claims] The positions of both ends of the workpiece on the X-axis of the reference orthogonal coordinates and the position of one end of the workpiece on the Y-axis of the coordinates are 2.
Calculation is performed based on a workpiece end detection signal from a sensor provided at the tip of the interaxial articulated arm and a signal from the arm tip position detection means, and the position of the workpiece is calculated based on the three position calculation values. The distance by which the reference point deviates from the reference position on the coordinates in the X-axis direction and the Y-axis direction and the angle by which the workpiece is rotated from the reference position on the coordinates are calculated, and the calculated value of the distance and the angle are calculated. A method for correcting positional deviation of a workpiece in a robot, characterized in that the value of a taught coordinate in a relational expression between the rotation angle of each axis of the arm and the coordinate is changed based on the calculated value.