JP3332666B2 - Article storage box position detection method and article storage box gripping device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an article storage device for detecting a mounting position of a box-shaped magazine for storing an article such as an assembly member or a workpiece to be gripped and transferred by a robot finger or the like. The present invention relates to a method for detecting a position of a box and an article storage box holding device.

[0002]

2. Description of the Related Art Conventionally, as a method of detecting a mounting position of a box-shaped magazine for storing an assembly member or a workpiece to be mounted at an arbitrary position, image processing using a camera is generally performed. Has been adopted. In this case, as shown in FIG. 2, a camera 12 for image processing is attached to a ceiling portion where the article gripping robot 10 is placed, or a finger that grips an article provided at a distal end portion of the robot arm. 11 (called a hand eye).

[0003]

However, in the conventional example configured as described above, since a photographing device such as the camera 12 and the illumination 13 is required, the cost and the size of the device are increased. In addition, when a camera is mounted on the ceiling, the range that can be recognized by the camera is narrowed, so that a plurality of cameras are required to perform image processing over a wider range, which also incurs high costs.

Further, when a plurality of cameras are mounted, it is necessary to align the camera coordinates with the robot coordinates (hereinafter referred to as calibration) for each camera, and the initial setting is complicated. On the other hand, in the case of a hand-eye, since the camera is attached to the tip of the robot arm, the weight of the tip increases, and the allowable load of the arm that grips the article decreases by the weight of the camera. This was the cause of the generated vibration.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and a first object of the present invention is to provide a method for detecting the position of an article storage box which is inexpensive, small, and capable of realizing a quick detection time, and an article storage box grip. It is to provide a device. A second object is to provide a method for detecting the position of an article storage box and an article storage box gripping device that can improve detection accuracy.

A third object is to provide a method for detecting the position of an article storage box which is not affected by the surface shape of the article to be gripped, and an article storage box gripping device.

[0007]

In order to solve the above-mentioned problems and achieve the object, a method for detecting the position of an article storage box according to the present invention comprises the following procedures. That is, a gripper for gripping an article storage box for storing a large number of articles and transferring the article to a predetermined position, and the article storage box provided on the gripper,
To detect two points on the first edge forming the outer shape of the box
At least two light sensors, and orthogonal to the first edge
At least one for detecting one of the second edges
Between two optical sensors and an optical sensor for detecting the first edge
In the article storage box gripping device having a distance of 1/2 or more of the length of the first edge portion , the flat surface can be placed at any position within the operation area of the gripping means. a position detecting method of an article storage box for detecting the position of the placed article storage box, wherein
An optical sensor for detecting the second edge is located at the second edge.
At least half the length from the intersection of the first edge and the second edge
The gripping means so as to scan the range of the object.
Control process to control the operation of the product storage box once in the diagonal direction
And two positions of the first edge by the control step.
Position information and one position information of the second edge portion are detected.
A detecting step, and position information detected by the detecting step
And a calculating step of calculating the position of the center of gravity of the article storage box based on the length of the side of the article storage box.

The article storage box holding device of the present invention is as follows.
Is provided. That is, an object for storing many articles
Gripper to grip the product storage box and transfer it to a predetermined position
A step, wherein the article storage box is in an operation area of the gripping means.
And an article storage box handle placed flat at an arbitrary position.
In the holding device, provided at the tip of the gripping means,
Detecting two locations on the first edge forming the outer shape of the article storage box
At least two light sensors for directing the first edge
At least for detecting one of the intersecting second edges
An optical sensor and an optical sensor for detecting the second edge
At the second edge between the first edge and the second edge
Scan a range of more than 1/2 length from the intersection
The gripping means in an oblique direction with respect to the article storage box.
Control means for controlling the operation once, and
The two pieces of position information of the first edge and the one of the second edge
Detecting means for detecting position information of a location;
Therefore, the detected position information and the length of the side of the article storage box
Calculating the position of the center of gravity of the article storage box based on
Means .

[0009] Preferably, the method and apparatus described above are used.
The optical axis diameter emitted from the optical sensor is
Large enough to be undetectable due to the surface shape of the
The diameter is set to a predetermined size.
The amount of deviation of the detection position of the sensor due to
You .

[0010]

[0011]

[0012]

As described above, the method for detecting the position of the article storage box and the article storage box gripping device according to the present invention are constituted, so that the two positions of the first edge of the article storage box to be gripped and the first edge of the first edge are provided. And one of the second edges orthogonal to the edge of
Since the position with respect to the article storage box gripping device can be calculated based on the detection result, it is possible to realize an inexpensive, compact, and fast detection time.

Further, by limiting the scanning range of the sensor, the detection accuracy can be improved. Also, by setting the diameter of the optical axis irradiated from the sensor to a diameter that is not affected by the surface shape of the article or the article storage box, the article storage box can be accurately detected. In addition, position deviation of an article caused by a large optical axis diameter can be corrected by storing an initial set value in advance by calibration.

[0014]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a schematic diagram showing the relationship between the sensor position of the finger and the scan position and direction with respect to the magazine. FIG. 3 is a side view showing the component gripping robot device of the present embodiment. In FIGS. 1 and 3, a box-shaped magazine 1 is placed at an arbitrary position and is a box for storing an assembly member, a workpiece, or the like. A plurality of the magazines 1 are stacked on a mounting member usually called a pallet 2 and are provided for supplying an assembly member or a workpiece to be used for assembling a certain apparatus. The component gripping robot 10 functions as a handling robot that grips the magazine 1 and has a finger 11 that grips the magazine at its tip. The magazines are held one by one by controlling the handling robot 11, and are transferred from, for example, an arbitrary component supply position to another used magazine placement position. Further, a plurality of optical sensors 14 are attached to a part of the finger 11 which is located above the magazine mounting position.

FIG. 1 shows the relationship between the sensor position of the finger and the scan position and direction with respect to the magazine by viewing FIG. 3 from above. As shown in FIG. 1, two sensors 14a and 14b are attached along one side direction 15 of the finger, and only one sensor 14c is attached near the center of the other side 16 orthogonal to the one side direction 15. 5
Is a connecting portion between the robot arm and the finger 11.
The handling robot 10 scans the finger 11 in the direction of arrow S1 above the magazine 1 so that each of the sensors 14 to 14c detects an edge portion of the magazine (an outer edge of the magazine) and takes in the position information. The distance 6 between the sensors 14a and 14b needs to be at least 1/2 the length of one edge portion 17 of the magazine 1 when scanning the finger 11. Further, the sensor 14c needs to be scanned from the middle point 7 of the other edge portion 18 of the magazine 1 toward the arrow S2.

<Optical Diameter Irradiated from Sensor> FIGS. 4 and 5 are diagrams for explaining the principle of setting the optical axis diameter of the optical sensor shown in FIGS. 1 and 3, and FIG. FIG. 5 shows a case where the shaft diameter is small, and FIG. 5 shows a case where the optical shaft diameter is large. First,
In determining the optical axis diameter of the optical sensor of this embodiment, as shown in FIG. 4, when the optical axis diameter emitted from the sensor is small, for example, assembling in a magazine as shown in FIG. If the surface shape of the workpiece 20 such as a member or a workpiece to be processed exceeds a certain curvature, light that should be reflected on the workpiece 20 will not return to the sensor 14, and the sensor may malfunction. Also, when light is applied to the gap formed between the work 20 and the magazine 11 as shown in FIG. 4B, if the surface shape of the gap has a certain curvature, the gap portion In this case, light reflected on the sensor does not return to the sensor, and the sensor may malfunction.

In view of such a problem, in this embodiment, as shown in FIG. 5, the diameter d of the optical axis irradiated from the sensor is increased. By increasing the optical axis diameter d in this manner,
As shown in FIG. 5A, the light hitting the surface of a magazine other than the work is reflected regardless of the curvature or shape of the work 20. It operates normally and the edge of the magazine can be detected. Further, as shown in FIG. 5B, even if a part of the light is irradiated to the gap between the work 20 and the magazine 11 and is not normally reflected, the light hitting the surface of the magazine other than the work is not affected. Because it will be reflected
The sensor operates normally, and the edge portion of the magazine can be detected.

<Control block of handling robot>
FIG. 6 shows a circuit block configuration of a control circuit system for controlling the handling robot. In FIG. 6, the teaching pendant 31 includes a display unit 32 and an instruction unit 33.
Having. The display unit 32 is input / output means for inputting position information for teaching the position of the finger to the robot, and for displaying and outputting the input result. The instruction unit 33 is a switch for instructing the robot to start or stop operation.

The controller 34 constitutes a central part for actually controlling the robot in accordance with instructions from the teaching pendant 31, and includes an interface circuit 35, a CPU 3
6, a ROM 37, a RAM 38, a position detection signal capturing means 40, and a servo control circuit 41. The interface circuit 35 exchanges control data with the teaching pendant 31. The CPU 36 performs servo control and finger trajectory planning calculation based on the control data. R
The OM 37 stores a control program for operating the CPU 36, a program for calculating the center of gravity of the magazine, and the like. The CPU 36 reads these programs from the ROM 37 when the power is turned on. RA
M38 stores a detection signal and the like output from the sensor. The position detection signal capturing means 40 is a circuit which captures the position information of the magazine detected by the sensor as a sensor detection signal. The servo control circuit 41 drives and controls a servomotor for controlling the robot arm and the fingers.
The handling robot 10 is connected to the controller 34 and its operation is controlled.

In the handling robot described above, the edge of the magazine is detected by the sensor, and the center of gravity of the magazine is calculated from the position coordinates of the finger at that time, whereby the position of the magazine placed at an arbitrary position can be determined. The grasping operation is performed by grasping the positional relationship with the finger. less than,
A method of calculating the position of the center of gravity of the magazine will be described. <Method of Calculating Center of Gravity> Next, a method of calculating the center of gravity of a magazine placed at an arbitrary position from the information detected by the sensor as described above will be described. FIGS. 7A and 7B
FIG. 4 is a schematic diagram for explaining a method of calculating the position of the center of gravity of the magazine. In calculating the position of the center of gravity described below, the handling robot takes in the position coordinates of a magazine or a finger based on its own spatial coordinate system. Therefore, the coordinates shown below mean position coordinates based on the origin of a handling robot (not shown).

First, in FIG. 7A, the sensor 14 is scanned, and the intersection A (x1, y) of the scanning direction of the sensors 14a, 14b and one edge portion 17 of the magazine.
1) When the equation of a straight line passing through B (x2, y2) is obtained, Y-y1 = (y2-y1). (X-x1) / (x2-x1) (Equation 1)

In the equation 1, (y2-y1) /
If (x2-x1) = m, then Y = m. (X-x1) + y1 (Equation 1 '). On the other hand, from Expression 1 ′, the intersection C (x3,
The equation of the perpendicular passing through y3) is obtained as follows: Y = −1 / m · (X−x3) + y3 (Equation 2) Here, when the intersection D is obtained from Expression 1 ′ and Expression 2, m · (X−x1) + y1 = −1 / m · (X−x3) + y3 Therefore, X = (mx1 + x3 / my1 + y3) / (M + 1 / m) (Equation 3)

When Y is obtained by substituting equation 3 into equation 1 ', Y = m ｛{(mx1 + x3 / my1 + y3) / (m + 1 / m) -x1} + y1 (Equation 4) . The intersection D obtained from Equations 3 and 4 is the coordinates of one corner of the magazine. Here, as shown in FIG. 7B, the length of one side 17 of the magazine is L1, and the other side 1 is
8 is L2, the deviation angle θ of the magazine from the finger
1 (θ2 = θ1 + 90 °), this intersection D (X,
Y) to the point E (cx1, cy) on the diagonal of the magazine
1) When F (cx2, cy2) is obtained, cx1 = X + L1 · cos θ1 cy1 = Y + L1 · sin θ1 cx2 = X + L2 · cos θ2 cy2 = Y + L2 · sin θ2, and the center of gravity (MX, MY) becomes MX = (CX2 + X2) , MY = (CY1 + CY
2) / 2. Note that the inclination θ1 of the finger with respect to the magazine is the inclination m of the straight line in Expression 1 ′.

In the above calculation method, since the position coordinates of the finger are taken in when the intersections A, B, and C are detected, the robot is instructed to position the finger by using the offset amount of the center of gravity H of the finger with respect to the center of gravity G of the magazine as an offset. By letting the deviation amount be (OX, OY),
The position of the center of gravity is as follows: X = (CX1 + CX2) / 2 + OXY = (CY1 + CY2) / 2 + OY

<Control of Handling Robot> Next, the operation up to gripping of the magazine by the handling robot using the above-described magazine calculation method will be described. FIG.
4 is a flowchart describing an article gripping operation of the handling robot of the present embodiment. In FIG. 8, when the process is started, first, in step S1, the finger 11 is moved above the magazine 1. Next, in step S2, the scan arrow S 1 direction indicated finger 11 in Figure 1.
Thereafter, in step S3, it is determined whether or not a detection signal has been input from the sensors 14a to 14c provided on the finger 11 to the controller 34. If the detection signal has been input (YES in step S3), the process proceeds to step S4. If no input has been made (NO in step S3),
Wait until a detection signal is input.

In step S4, the controller 34 takes in the position coordinates of the finger 11 in the spatial coordinate system of the handling robot. Then, step S5
In, the controller calculates the coordinates of the center of gravity of the magazine for the finger 11 from the input signal from the sensor and the position coordinates of the finger. In step S6, the teaching pendant 31 teaches the position with the amount of deviation of the finger from the center of gravity of the magazine as an offset, and the finger 11 is adjusted to the center of gravity of the magazine 1 in advance, and the finger is moved. Then, step S7
Then, the control up to the magazine gripping operation by the handling robot of this embodiment is ended by gripping the magazine 1 with the finger 11.

<Effects of the Embodiment> According to the embodiment described above, the magazine 1 is detected by detecting two points A and B on one side of the magazine 1 to be gripped and one point C on the other side orthogonal to this side. Since the position of the handling robot in the coordinate system and the position of its center of gravity can be calculated, the deviation amount can be easily taught to the robot.

Further, the scanning range of the sensor 14 is
By limiting to one direction, detection accuracy can be improved.
In addition, by setting the diameter of the optical axis irradiated from the sensor 14 to a large diameter that is not affected by the surface shape of the magazine or the work, the edge of the magazine can be accurately detected.

The deviation of the magazine detection position caused by the thick optical axis can be accurately corrected by storing an initial set value in advance by calibration. The present invention can be applied to a modification or a modification of the above embodiment without departing from the gist of the invention. For example, in this embodiment, a laser beam sensor is used as a magazine detection sensor, but an ultrasonic sensor may be used.

[0030]

As described above, since the method for detecting the position of the article storage box and the article storage box gripping device according to the present invention are constituted, the two positions of the first edge of the article storage box to be gripped and the two positions are described. Since the first edge and one point of the second edge orthogonal to the first edge are detected, and the position with respect to the article storage box gripping device can be calculated based on the detection result, it is inexpensive, small, and quick in detection time. Can be realized.

Further, by limiting the scanning range of the sensor, the detection accuracy can be improved. Also, by setting the diameter of the optical axis irradiated from the sensor to a diameter that is not affected by the surface shape of the article or the article storage box, the article storage box can be accurately detected. In addition, position deviation of an article caused by a large optical axis diameter can be corrected by storing an initial set value in advance by calibration.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a relationship between a sensor position of a finger and a scan position and a direction of a magazine according to an embodiment of the present invention.

FIG. 2 is a diagram showing a conventional position detection method.

FIG. 3 is a diagram showing a position detection method according to an embodiment of the present invention.

FIG. 4 is a diagram illustrating a change in a position detection operation based on a change in the diameter of an optical axis emitted from a sensor.

FIG. 5 is a diagram illustrating a change in a position detection operation based on a change in the diameter of an optical axis emitted from a sensor.

FIG. 6 is a block diagram of a control system of the article gripping robot according to the present invention.

FIG. 7 is a diagram illustrating a method of calculating a center of gravity position of a magazine.

FIG. 8 is a flowchart up to a gripping operation by the article gripping robot of the present embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Magazine 2 ... Pallet 10 ... Handling robot 11 ... Finger 14 ... Sensor 20 ... Work 31 ... Teaching pendant 34 ... Controller

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01B 11/00 G05D 3/12

Claims (4)

(57) [Claims] 1. A multiple article gripping an article storage box for storing, a gripping means for transferring a predetermined position, before
Provided on the holding means, before forming the outer shape of the article storage box.
At least two for detecting two locations on the first edge
And a second edge portion orthogonal to the first edge portion.
At least one optical sensor for detecting one location,
The distance between the optical sensors for detecting the first edge is the first distance.
In an article storage box gripping device having a length equal to or longer than half the length of an edge portion, an article for detecting a position of an article storage box placed two-dimensionally at an arbitrary position within an operation area of the gripping means. A method for detecting the position of a storage box, wherein an optical sensor for detecting the second edge is provided on the second edge.
And at least １ ／ from the intersection of the first edge and the second edge
Forward the gripping means so as to scan a range of length
Control to control the operation of the storage box once in the diagonal direction
Step and two positions of the first edge by the control step.
For detecting information and position information of one of the second edges
The position information detected by the detecting step and the article collection.
Position detecting method of the article storage box, characterized in that it comprises a calculation step of calculating the center of gravity of the article storage box on the basis of the length of the side of the pay box. 2. An optical axis diameter emitted from the optical sensor is:
The size is set so as not to be undetectable due to the surface shape of the article or the article storage box, and the shift amount of the detection position of the sensor by setting the optical axis diameter to a predetermined size is corrected in advance. The method for detecting the position of an article storage box according to claim 1 . 3. A gripping means for gripping an article storage box for storing a number of articles and transferring the article to a predetermined position.
And the article storage box is within the operating area of the gripping means.
An article storage box gripping device placed two-dimensionally on an arbitrary position, provided at the tip of the gripping means, and configured to detect at least two first edges forming the outer shape of the article storage box.
Two optical sensors , at least one optical sensor for detecting one point of a second edge orthogonal to the first edge, and an optical sensor for detecting the second edge are the second optical sensor; On the edge of
And at least １ ／ from the intersection of the first edge and the second edge
Forward the gripping means so as to scan a range of length
Control to control the operation of the storage box once in the diagonal direction
Means, and two positions of the first edge by the control means.
For detecting information and position information of one of the second edges
Means, the position information detected by the detection means and the article collection
And a calculating means for calculating a position of a center of gravity of the article storage box based on a length of a side of the storage box. 4. The optical axis diameter emitted from the optical sensor is:
The size is set so as not to be undetectable due to the surface shape of the article or the article storage box, and the shift amount of the detection position of the sensor by setting the optical axis diameter to a predetermined size is corrected in advance. The article storage box holding device according to claim 3 .