JPH08376B2 - Robot controller capable of switching position correction methods - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a robot controller, and more particularly to switching of a position correction method for position correction between a teaching point and a work position in a teaching playback type robot. is there.

2. Description of the Related Art Conventional position correction methods for robots include a method of designating parallel and rotational movement components of a correction amount (or a corrected position) (hereinafter, this method will be referred to as method A), and a method of preliminarily using a robot controller. There is a method (hereinafter, this method is referred to as method B) in which the actually measured positions of the three reference points stored in are designated and the correction amount is calculated therefrom.

The method A is, as shown in FIG. 3, taught point PT (X
T, YT, ZT) and the working point detected by the image sensor, that is, the incremental amount (Xc-XT, Yc) between the correction points Pc (Xc, Yc, Zc).
-YT, Zc-ZT), or in the case of absolute specification, the position is corrected by specifying the position (Xc, Yc, Zc) of the correction point in the sensor coordinate system (Os-Xs-Ys-Zs). further,
With this correction, the fourth
As shown in the figure, the axis which is the gripping direction of the hand 3'of the work 6 detected by the camera 7 of the image sensor, that is, in the case of FIG. 4, the Yt axis is the sensor coordinate system (Os-Xs-Ys-Zs). Xs −
The axis Yt ′ projected on the Ys plane and the predefined tool coordinate system (TCP-Xt-Yt-Zc) are used for incremental correction, between the Yt ′ axis and the Yt axis around the axis parallel to the Zs axis. Rotation amount, and in the case of absolute correction, the Yt 'axis
The angle formed by the Yt 'axis and the Xs axis around the axis parallel to the Zs axis is used as the correction amount, and the parallel and rotational movement components of the correction amount are designated and corrected.

On the other hand, in the above method B, as shown in FIG. 5, three points P1, P2, P3 that are not on the same straight line on the work object as reference points are taught, and the reference point positions P1, P2, P3 are taught. And the positions P1 ', P corresponding to the reference point position measured by the image sensor during the reproduction operation.
This is a method of calculating the correction matrix from 2 ', P3' (correction points) and calculating the deviation and rotation of the work object.The method is calculated by the robot controller and by the image sensor. There are two cases in which the correction matrix is transmitted from the sensor side to the robot controller, and the correction matrix [c] is obtained by the robot controller or the sensor side as follows.

Set the coordinate system of the taught reference points P1, P2, P3 to (,,)
Then, the line segment P1P2 direction is the X axis, If the Y axis is the axis that is orthogonal to i in the plane P1P2P3 and the side with P3 is positive, and the intersection with the X axis is P4, then as shown in FIG. However Also, if the Z axis is determined so as to form a right-handed system, == ... (3) Similarly, the coordinate system created by the correction points P1'P2'P3 ' However, And the positions of points P1 and P1 'on these coordinate systems are P1 = (P1
X, P1Y, P1Z), P1 '= (P1X', P1Y ', P1Z')
Define matrices [A] and [B] of 4 rows.

From the above two matrices [A] and [B], the correction matrix [C] is [C] = [B] × [A] ^-1 (6) where [A] ^-1 is the inverse of the matrix [A] A matrix is obtained, and the correction matrix [C] is obtained and correction is performed.

In the two position correction methods described above, the position correction method A or B is set in the storage unit that stores the designation of the position correction method by parameter setting according to the work target, and the control device is set in this storage unit. Based on the command, the selected position correction method A or B is executed.

Problems to be Solved by the Invention As described above, in the conventional robot, the position correction method is executed by only one selected correction method.
When one robot performs work at a plurality of points and needs to correct the position at each work position, it is unavoidable to apply the position correction method of either A or B at all the points. There is no problem if the position correction method currently selected is suitable, but the position correction method A is suitable for one work target, the position correction method B is suitable for the other work target, and the robot is When working continuously, one of the position corrections is accurate, but the other cannot be corrected accurately.

Therefore, it is an object of the present invention to provide a robot control device capable of switching the position correction method at any time during the operation of the robot.

Means for Solving Problems According to the present invention, data of a storage unit that stores designation of a selected position correction method executed by a control device is programmed by a switching command code programmed in an operation program of a robot or a work target of a robot. The above-mentioned problem was solved by rewriting with a signal from an image sensor for detecting the position and switching the position correction method at an arbitrary point during the operation of the robot.

When teaching the work motion to the work robot and creating a motion program, select the position correction method that is suitable for the position correction of multiple work points and select each work point with the selected position correction method. When the switching command code is programmed to specify the position correction method and the position correction method is specified, if the switching command code is read during the playback operation of the robot, the data in the storage unit that specifies the position correction method is rewritten. As a result, the correction process is performed by the designated position correction method. In addition, the rewriting of the data in the storage unit that specifies the position correction method is performed by rewriting so that the position correction method suitable for each work target is specified by the signal from the image sensor, so that the optimum position suitable for each work target can be obtained. Perform the correction method.

Embodiment FIG. 1 is an explanatory diagram of the operation of a robot performed by an embodiment of the robot controller of the present invention. A robot controller 1 is connected to a controller 2 of the image sensor, and the robot controller 1 is connected to a robot mechanism 3. In the present embodiment, the work 6 conveyed by the parts feeder 4 is gripped by the robot hand and the work 6 is stacked at each stacking position on the pallet 5. Reference numeral 7 is a first camera for detecting the position of the work 6 of the parts feeder 4, and 8 is a second camera for detecting the position of the pallet 5. In the case of such work, in order to detect the work 6 on the parts feeder 4 with the camera 7 and correct the position of the robot, the work detected by the position correction method A described above with respect to the teaching reference position of the work 6 is detected. The work 6 can be gripped more accurately when the position and rotation of 6 are corrected.

On the other hand, when the workpieces 6 are stacked on the pallet 5, the position and rotational posture of the pallet 5 pose a problem, so the reference points 3 taught by the position correction method B and the 3 points detected by the camera 8 are given. It is better to correct the position by.

Therefore, the position correction method A is used when the work 6 is held on the parts feeder 4, and the position correction method B is used when the work 6 is stacked on the pallet 5.

FIG. 2 is a view showing a main part of the robot control device 1 and a connection relationship between the robot control device 1 and other elements. The robot control device 1 has a central processing unit (hereinafter referred to as CPU) 10, The CPU 10 includes a ROM 11 storing a control program, a RAM 12 used for temporary storage of data, a data memory 13 for storing system parameters and setting data, a teaching program input from a teaching operation panel 17, and a serial memory. A communication controller 14 and a servo circuit 16 for driving and controlling the servo motors of the respective axes of the robot mechanism section 3 are connected by a bus 15. The serial communication controller 14 is connected to the controller 2 of the image sensor and the teaching operation panel 17.

The data memory 13 has a system parameter section for storing the validity and invalidity manually set by the teaching operation panel 17 of the position correction methods A and B, and the position correction method set as valid is adopted and both are valid. If set to, for example, the position correction method B is preferentially used.

Further, the setting data storage section of the data memory 13 is provided with a storage section for storing a designation code of a position correction method to be used. For example, in the present embodiment, the setting register 70 is used and "0" is stored in the register. If so, the position correction method in which the parameter is set by the manual operation is selected, that is, the position correction method by the manual operation is adopted as in the conventional case. If "1" is stored, the position correction method A is adopted, and if "2" is stored, the position correction method B is adopted.

So, as a code to select the position correction method A, B,
For example, a code S63 is provided, and the code S63, the setting register number 70 that specifies the position correction method, and the selected position correction specification code (0, 1, 2) are used to correct the position correction method A, B can be selected by switching. That is, the format of this switching command is as follows.

S63,70, X; (X = 0,1,2) (7) In the equation (7), if the value of X is "0", "0" is set in the setting register 70, The position correction method manually set as the system parameter is selected, and it becomes the same as the conventional one. Also, the value of X is "1"
Then, "1" is set in the register 70 and the position correction method A is selected. Register when the value of X is "2"
“2” is set in 70, and the position correction method B is selected.

For example, if the following is programmed in the program for performing the operation shown in FIG. 1, the optimum position correction method will be selected and executed.

G45 is a G code for instructing to perform position correction. When the work 6 is taken from the parts feeder 4 by the above program, the position and orientation of the work 6 of the image taken from the camera 7 by the position correction method A is used. Then, the position of the robot is corrected from the position and orientation taught in advance as the reference position. Further, when the work 6 is stacked on the pallet 5, the sensor control unit 2 or the sensor control unit 2 is operated from the positions corresponding to the three reference positions previously taught by the position correction method B and the three reference positions of the image captured from the camera 8. The robot controller 1 calculates the correction matrix and controls the position of the robot.

As described above, the position correction method based on the image obtained by the camera 7 is A, and the position correction method based on the image obtained by the camera 8 is B. The position correction method is determined by the camera corresponding to the work. The setting data of the register 70 may be switched to "1" or "2" by a command from the control unit 2 to select the position correction method suitable for each work.

EFFECTS OF THE INVENTION Since the present invention enables the position correction method to be used at any time during the operation of the robot, the optimum position correction method according to the work of the robot is selected to determine the teaching point and the work position. It is possible to correct the position between the two, and to make the robot operate accurately. In addition, according to the configuration in which the position correction method is selected by rewriting the data in the storage unit by programming the switching command code in the operation program of the robot, regardless of the deployment position of the image sensor or the number of individual image sensors, Since the position correction method can be selected completely arbitrarily according to the needs at that time, even when performing various tasks using a single image sensor, it is always the most suitable for the task. A position correction method can be selected to perform position correction between the teaching point and the work position.

[Brief description of drawings]

FIG. 1 is a diagram for explaining the operation of a robot performed according to an embodiment of the present invention, and FIG. 2 is a diagram showing a connection relationship between a main part of a robot control device and other elements according to the embodiment, FIGS. FIG. 4 is an explanatory view of the position correction method A, and FIGS. 5 and 6 are explanatory views of the position correction method B. 1 ... Robot control device, 2 ... Sensor control unit, 3 ...
Robot mechanism, 4 ... Parts feeder, 5 ... Pallet, 6,7 ... Camera.

Claims (1)

[Claims] 1. A plurality of position correction methods for correcting an error between a teaching point and a work position are stored in advance according to the work content of a robot, and one position correction method is selected from among these to select the position. In a robot control device that performs correction, data in a storage unit that stores designation of a position correction method executed by the control device is changed by a switching command code programmed in a robot operation program or a work target of the robot. Switching the position correction method so that the position correction method suitable for the work to be performed on the work target is selected by rewriting with the signal from the image sensor that detects the position correction method, and the position correction method is switched at any time during the robot operation. Possible robot controller.