JPH1011146A - Device for correcting stop posture of mobile object - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect the deviation of a mobile object such as an industrial robot from the position of an orign after working by improving the measuring accuracy of a rotational angle. SOLUTION: A mark sheet 2 on which prescribed matchmarks are written at a prescribed interval is arranged on a prescribed position on the surface of an object 20 to which a mobile object 10 is applied and a CCD camera 1C and a two-shaft inclination angle detecting function 1G are fitted to the prescribed positions of the mobile object 10. A matchmark on the mark sheet 2 is detected by the camera 1C and a position and a posture error between the prescribed position of the object and that of the mobile object are detected based on the matchmark detection data and the detection value of the function 1G and the position and the posture errors are corrected. It is suitable to use a two-dimensional gyro as the inclination angle detecting function 1G.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of an apparatus for correcting a stop posture of a moving body such as an industrial robot which needs to confirm and correct its position, such as a moving body.

[0002]

2. Description of the Related Art Generally, a moving body such as an industrial robot is made and used so as to perform a position correction at a stop based on a taught position by teaching the moving position in advance. However, while the moving body is moving and performing the work, the posture at the time of the stop is not constant due to the movement, and an error occurs, so that the required operation cannot be performed at the position taught first. Therefore, for example, it is necessary to set the position before the movement of the moving body as the origin position, return to the origin position after the work is completed once, detect an error after the movement at the origin position, and correct it. A conventional moving body stop posture correction device used for such a purpose is configured as shown in FIG. 4, for example. In FIG. 4, reference numeral 1C denotes a mark sheet 2 at a predetermined position of a working machine provided at the tip of the arm of the industrial robot.
The CCD camera 1a provided in a posture facing the camera 1a is a code for transmitting image data of the CCD camera 1C and supplying power. The mark sheet 2 includes one or a plurality of predetermined shapes having predetermined marks at appropriate intervals. In FIG. 4, six matching marks 2a are arranged at positions forming a rectangular shape. It is assumed that the mark sheet 2 is attached to a predetermined position of a ground device that holds a work, a cassette, and the like to be transferred. In the above configuration, the back of the robot body (not shown) and each arm (not shown)
Is stopped as instructed, the CCD camera 1C captures the mark 2a, and the mutual shape of the captured six mark images is used to determine the degree of deviation from the origin indicating the reference position.
They are detected and corrected three-dimensionally as quantities such as length and angle.

[0003]

By the way, it is difficult to accurately measure all three-dimensional axes by the above-described attitude measuring means of the conventional stop attitude correcting apparatus.
That is, as shown in FIG. 5, all the three-dimensional axes to be measured are position information of three axes x, y, and z, and three axes of α, β, and δ with respect to three axes of x, y, and z. Rotation information is required. C
For example, an image as shown in FIG. 6 is obtained according to the state of the stop posture of the CD camera with respect to the mark sheet. In (A), (B), and (C) of FIG.
When the axis, the y-axis, and the z-axis are taken, it is assumed that a is a reference image in a state in which a desired stop posture is satisfied, and b is a captured image. That is, FIG. (A) shows a situation in which rotation [delta] ₁ with respect to the z-axis with y ₁ shifts to x _1, y direction in the x-direction, and FIG. (B) is rotated alpha ₁ relative to the x-axis status (C) shows a state in which there has been no rotation in the axial direction and has moved in the z-axis direction. By the way, the achievable dimensions of the above-mentioned mark sheet naturally have a limit in practice, for example,
The dimensions are such as 0 mm x 80 mm. Therefore, as is apparent from FIG. 6, it is difficult to sufficiently increase the measurement accuracy of a minute rotation error about the x-axis. Similarly, it is also difficult to sufficiently increase the measurement accuracy of a minute rotation error about the y-axis. SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems (problems) of the prior art, and to provide a stop posture correction device for a moving body with improved measurement accuracy of a rotation angle.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a stop posture correcting apparatus for a moving body according to the present invention has a predetermined position provided at a predetermined position on the surface of a target body on which the moving body acts. A mark sheet on which a mark is written, a CCD camera at a predetermined position of the moving body and a biaxial inclination angle detection function,
A match mark on the mark sheet is detected by the D camera, and a position and posture error between a predetermined position of the target object and a predetermined position of the moving body is detected based on the detection data of the match mark and the detection value of the inclination angle detection function. The position and posture errors are configured to be corrected. The tilt angle detection function includes 2
A dimensional gyro may be used. With this configuration, the error due to the rotation angle is also measured with high accuracy, and the stopping posture of the moving object with respect to the target object can be accurately corrected.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a combination of an industrial robot, which is an example of a moving body equipped with a stop posture correcting device of the present invention, and a ground apparatus on which a cassette to be transferred by the industrial robot is arranged. FIG. 2 shows an outline of a control function incorporated in the above-described stop posture correcting apparatus, and FIG. 3 shows a flow showing an operation when the control function is constituted by a computer or the like. In FIG. 1, reference numeral 10 denotes an industrial robot (hereinafter, referred to as a robot) which is a moving body, and a plurality of arms 12 and 13 are connected to a robot main body.
A gripping function unit 1 provided with a mechanism for gripping a transferred object to be transferred by the robot is connected to a tip end of the robot. The arms 12 and 13 and the gripping function unit 1 are configured to rotate with each other. In addition, gripping function unit 1
Is mounted with a CCD camera 1C whose imaging direction is fixed in a predetermined direction (downward in the figure), and measures the inclination angles in the x-axis direction and the y-axis direction, that is, the rotation angles α and β shown in FIG. The two-dimensional inclination angle detection function 1G, for example, 2
A dimensional gyro (hereinafter described as a gyro) is provided. A mechanism 1H for gripping the object to be transferred is coupled to the tip of the gripping function unit 1 so as to be movable in accordance with conditions such as the structure of the object to be transferred. 20 is a gripping function unit 1
Is a reference object for the stop posture of the vehicle, and is composed of a ground device 21 and a cassette 22, and the cassette 22 is placed on, for example, the upper surface of the ground device 21. The mark sheet 2 is disposed at a predetermined position above the ground device 21 in a reference posture.

FIG. 2 is a connection diagram showing a configuration of a control function for executing the stop posture correcting apparatus of the present invention. 1C, a processing unit (hereinafter referred to as a CCD camera) for processing an electronic signal captured by the CCD camera described with reference to FIG.
The gyro (inclination angle detection function) described in (1) and (2) include the electronic signal processing unit. The signals output from the CCD camera 1C and the gyro 1G are input to a signal (data) processing function unit 2C. The signal (data) processing function unit 2C also has a function of processing an operation signal of the robot, and receives a command signal SM from an upper system and / or a manual operation function of the robot 10. The command signal SM is a signal transmitted through a signal transmission line transmitted from a plurality of signal sources, but is represented by one input here. The signal (data) processing function unit 2C is mainly composed of, for example, a computer, processes input signals, and outputs an operation signal to a driving unit 3 such as each arm of the robot. The drive unit to be operated by the robot is composed of a plurality of elements, but is represented by one block 3 here.

Next, a signal processing operation according to the present invention executed by the signal (data) processing function unit 2C will be described with reference to FIG. In FIG. 3, when the mechanical units such as the robot main body and each arm stop at a predetermined position in accordance with a command transmitted from a host system or the like, a three-dimensional centering command is output inside the signal processing function unit 2C (step 1). . When the three-dimensional centering command is output, in a visual function mode for processing an image signal of the CCD camera, a video signal imaged by the CCD camera is captured (S1), and a matching mark is extracted (S2). That is, the diameter of each combination mark and the distance between each combination mark are obtained from the imaging signal. From these values, the center of gravity value of the combination mark (coordinates indicating the position of the center of gravity)
Is calculated and recorded in a predetermined storage function (S3). Thereafter, 1 is added to the counter function provided in the signal processing function unit 2C (S4), and the above-described operations from S1 to S4 are performed until the counter function content value reaches a preset number N, for example, 5. Is repeated (S5). Counter function content value is N
(S5), the content value of the counter function is reset, and the average value (data) of the center-of-gravity values of the above-described N matching marks is obtained (S6). The magnitude of the center of gravity value and the position data are compared with reference point data provided in the signal processing function unit 2C, and a rotation angle component related to rotation about the x axis and a rotation angle related to rotation about the y axis are calculated. Except for the components, the three-dimensional stopping posture of the other gripping function units is calculated (S7).

On the other hand, when the three-dimensional centering command is output, in the inclination angle detection function mode for processing the output signal of the gyro, the data of the gyro is fetched (S1-
1) Output the value (data) of the rotation angle (φ) about the x axis as the center of rotation (S2-1), and output the value (data) of the rotation angle (θ) about the y axis as the center of rotation. (S3-
1).

The data obtained in the visual function mode and the data obtained in the tilt angle detection function mode are combined to obtain the three-dimensional stopping posture of the gripping function unit 1. Therefore, the three-dimensional stopping posture of the gripping function unit 1 is compared with a previously specified command value. Is calculated (step 2), and a correction command for correcting the above-mentioned deviation is output to the drive function of each mechanism of the robot (step 3). The stop posture of each mechanism is corrected by this correction command (step 4), and the robot proceeds to the next step operation, and holds, for example, a cassette.

The present invention is not limited to the above description of the flow. For example, in the above-described flow, it has been described that the robot body and each arm and other mechanical units are stopped at predetermined positions in Step 1, and then the stop posture correction operation is performed. When approaching, the above-described correction operation may be activated to continuously and repeatedly process the image data obtained by the CCD camera and the output data of the two-dimensional gyro, so as to stop at the correct stop posture. It has been described that the correction command is output in step 3 and the correction is executed in step 4. However, after issuing the correction command, each of the visual function mode and the tilt angle detection function mode is operated while operating each mechanism. Returning to S1 and S1-1, C
The image data obtained by the CD camera and the output data of the two-dimensional gyro may be continuously and repeatedly processed to stop at a correct stop posture. In the visual function mode, it has been described that the center of gravity value of the matching mark is obtained, and the shift amount of the stop posture is obtained by the data indicating the center of gravity. The deviation value of the stopping posture may be obtained by comparing the diameter value of each of the matching marks and the mutual positional relationship with a reference pattern.

The above-described embodiment shows an example to which the present invention is applied, and can be modified as follows, for example. Although the mark sheet has been described as being constituted by six circular marks each arranged in a rectangular shape, the mark data on the imaged mark sheet and the data indicating the reference stop posture are compared on a computer. If the shift amount of the stop posture is obtained, the number and shape of the matching marks may be set arbitrarily and appropriately. For example, the matching mark may be made into one quadrilateral, or any other suitable shape, number, and arrangement graphic, and a processing function corresponding to this graphic may be provided. Although the stop posture correction apparatus of the present invention has been described as being mounted on the signal (data) processing function unit of the robot (moving body),
A dedicated signal (data) processing function may be configured, or the visual function and the tilt angle detection function may be individually dedicated signal (data) processing functions. Further, all functions or predetermined functions described in the flow may be configured by hardware using electronic components, or may be processed by a computer program. The above-described flow is an example for executing the function according to the present invention, and the flow and the function capable of executing the flow may be formed in an order and configuration necessary for executing the above-described function. In the above-described embodiment, the moving body is an industrial robot, and a description has been given of an example of the structure. However, it is obvious that a moving body having another structure can be easily realized by applying the above technical idea. In the present invention, the imaging function is described as a CCD camera.
A camera and a corresponding image detection function may be used. If a two-dimensional gyro is used as the tilt angle detection function,
Although a proven characteristic can be obtained, another inclination angle sensor may be used as long as a desired measurement angle accuracy is obtained.

[0012]

Since the present invention has the above-described configuration, it is possible to easily and reliably detect and determine the error of the predetermined position of the moving body from the target values of the three moving axes and the three rotating axes. Can be performed. In addition,
If a two-dimensional gyro is used as the tilt angle detection function, it has a track record as a tilt angle sensor, which facilitates design and assembly.

[Brief description of the drawings]

FIG. 1 is a schematic side view showing a configuration of a moving object and a target object to which the present invention is applied.

FIG. 2 is a schematic block diagram illustrating a configuration of a signal processing function to which the present invention is applied.

FIG. 3 is a schematic flowchart illustrating an embodiment of the present invention.

FIG. 4 is a schematic perspective view illustrating an example of a visual function used in both the present invention and the prior art.

FIG. 5 is a vector diagram illustrating types of displacement of a moving object.

6A and 6B are diagrams for explaining the theory of determining a stop posture shift in the visual function example shown in FIG. 4. FIG. 6A is a diagram in which a position shift in the x-axis and y-axis directions and a rotation δ with respect to the z-axis are combined. If
FIG. 7B shows the case of rotation α with respect to the x-axis, and FIG. 7C shows the case of position shift in the z-axis direction.

[Explanation of symbols]

 1: gripping unit 1C: CCD camera 1G: tilt angle detection function (two-dimensional gyro) 2: mark sheet 2a: matching mark 10: moving body (industrial robot) 11: moving body (industrial robot) body 12, 13: Arm 20: Target object 21: Ground equipment 22: Transferred object (cassette)

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[Procedure amendment]

[Submission date] August 9, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction contents]

On the other hand, when the three-dimensional centering command is output, in the inclination angle detection function mode for processing the output signal of the gyro, the data of the gyro is fetched (S1-
1) Output the value (data) of the rotation angle (α) with the x axis as the center of rotation (S2-1), and output the value (data) of the rotation angle (β) with the y axis as the center of rotation (S3-
1).

Claims (2)

[Claims] 1. A mark sheet in which predetermined mating marks provided at predetermined intervals on a surface of an object on which a moving body acts are provided. A CCD camera and a two-axis tilt angle detecting function are provided at a predetermined position of the moving body. Detecting a matching mark on the mark sheet by the CCD camera, and determining a position between the predetermined position of the target object and the predetermined position of the moving body based on detection data of the matching mark and a detection value of the tilt angle detection function. And a posture / posture error, and corrects the position / posture error. 2. The apparatus according to claim 1, wherein a two-dimensional gyro is used as the inclination angle detecting function.