JP5196156B2 - Work picking method in bulk picking equipment - Google Patents

Description

  The present invention relates to a work picking method for picking out works one by one by a robot in a bulk picking apparatus.

The bulk picking device refers to a device that individually recognizes the position / posture of a workpiece from loosely stacked components placed in a messy manner and takes out the workpieces one by one by a robot.
For example, Patent Documents 1 and 2 have been proposed as work picking methods to be applied to such a bulk picking apparatus.

Patent Document 1 aims to continue the pick-up operation even when it is determined that the pick-up cannot be performed.
Therefore, as shown in FIGS. 4 (A) and 4 (B), this apparatus detects all objects detected by the visual recognition device 53 in S2 when the visual recognition device 53 cannot detect the objects in S1. As a result of the interference check, when it is determined that it cannot be picked up, the manipulator 54 is operated in the box in S3, and the parts are detected again by the visual recognition device 53 in S1, and the picking up operation is continued. .
In FIG. 4A, 51 and 52 are cameras, 55 is a robot controller, and 56 is a communication line.

Patent Document 2 aims to reduce alarm output and operation stop frequency as much as possible by trying a gripping operation again when a gripping error occurs.
Therefore, as shown in FIGS. 5 (A) and 5 (B), this apparatus and method are configured to move a hand 64 provided so as to be able to move forward and backward to grip a hand receiver 67 of a conveyed product 65. In the gripping device of 65, when a gripping error detecting means (65, 66, 60) for detecting a gripping error of the handle 67 by the hand 64 and a gripping error detecting means are detected, the hand 64 is moved backward. The control unit 60 controls to change the advance amount of the hand 64 and advance again to grip the handle 67.
In FIGS. 5A and 5B, reference numeral 63 denotes a pusher.

JP 2000-263480 A, “Bin Picking Device” Japanese Patent No. 3540676, “Grip device and gripping method for transported object”

  The method of Patent Document 1 has a problem that it takes time to grip the next workpiece because the manipulator is operated in the box when the visual recognition device cannot detect the object.

  In the apparatus and method of Patent Document 2, when a gripping error is detected by the gripping error detection means, the hand is moved backward for retrying, and the amount of advancement of the hand is changed to move forward again. Therefore, the operation efficiency is low. There was a problem. Or, since it has a structure in which the hand is engaged with the gripping part of the workpiece by retreating the hand, it is necessary to move backward once after moving to the advance position when a gripping error is detected. There was a problem of low efficiency.

  In addition, when gripping a workpiece with a suction pad type hand against loosely stacked parts placed in a messy manner, even if the gripping state is good when the hand is in close contact with the workpiece, In some cases, gripping may fail due to detachment of the workpiece when the workpiece is taken out due to entanglement or adsorption failure.

  In addition, distance sensors that measure the three-dimensional shape of loosely stacked workpieces have large detection errors (errors in the depth direction), so gripping errors often occur even when the hand is moved to the detection position. There was a high problem.

  The present invention has been developed to solve the above-described conventional problems. That is, the object of the present invention is to detect a gripping error accurately and retry efficiently even if there are entanglements or gripping defects between workpieces, and the workpiece gripping target position includes an error. It is another object of the present invention to provide a work picking method in a bulk picking apparatus that can grip a work in a short time, thereby shortening the picking time and increasing the success rate of picking and the operating rate of the apparatus.

According to the present invention, for a plurality of workpieces stacked in a messy and bulky manner,
Advance the robot hand to the workpiece gripping target position, check the gripping state,
If the gripping state is not good, change the workpiece gripping target position and repeat the forward movement without retracting the robot hand until the gripping state is reached ,
When the gripping state is good, the robot hand is retracted to take out the workpiece, and the gripping state is confirmed again.If the gripping state is not good by the confirmation, the workpiece gripping target position is changed, and again, There is provided a work picking method in a bulk picking apparatus characterized by moving a robot hand to a work gripping target position .

  Also, after measuring the stacked workpieces three-dimensionally with a distance sensor and comparing the obtained measurement results with the 3D CAD model of the workpiece, the robot hand is moved after recognizing the three-dimensional position and orientation of each workpiece. Move to the hand standby position.

According to the method of the present invention, to check the gripping state by the work gripping target position, when the grasping condition is not good, the forward without retracting the robot hand until gripping state by changing the work gripping target position Since this is repeated , even if the workpiece gripping target position includes an error, the workpiece is not retracted until the gripping can be confirmed, so that the operation efficiency is good.

  In addition, when the gripping state is good, the robot hand is moved backward to take out the workpiece, the gripping state is confirmed again, and when the gripping state is not good, the workpiece gripping target position is changed, and the robot hand is again Since the workpiece is moved to the workpiece gripping target position, it is possible to accurately detect a gripping error even if there are entanglements between workpieces or gripping failure.

  Therefore, even if there are entanglements between workpieces, gripping defects, etc., it is possible to accurately detect a gripping error and retry efficiently, and even if the workpiece gripping target position contains errors, Thus, the picking time can be shortened, and the success rate of picking and the operating rate of the apparatus can be increased.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the common part in each figure, and the overlapping description is abbreviate | omitted.

  FIG. 1 is an overall configuration diagram of a bulk picking apparatus including a workpiece supply apparatus according to the present invention.

  This bulk picking device includes a distance sensor 20, a robot 22, a robot hand 24, and a three-dimensional object recognition device 26.

The distance sensor 20 is controlled by the distance sensor control device 21 and measures the three-dimensional shape of the workpiece 1 stacked in the workpiece supply device 10.
The robot 22 is controlled by the robot control device 28, takes out the target workpiece 1 from the workpiece supply device 10, and arranges it in an alignment tray (not shown).
The robot hand 24 is attached to the hand of the robot 22 to hold the workpiece 1 and is controlled by the hand control device 25.
The three-dimensional object recognition device 26 communicates distance information and position information with the distance sensor control device 21 and the robot control device 28, and recognizes the three-dimensional position and posture of the target workpiece 1.
Furthermore, the robot controller 28 receives a gripping state from the hand controller 25 and transmits a gripping command.

In this example, the robot 22 is an articulated robot. However, the present invention is not limited to this, and other types may be used as long as the workpiece can be taken out from above the workpiece supply apparatus 10.
In this example, the distance sensor 20 is a laser radar that performs measurement based on the principle of triangulation using laser light. The distance sensor 20 can obtain the three-dimensional shape information of the object by scanning the laser beam two-dimensionally.

  The above-described bulk picking device measures the three-dimensionally measured workpiece 1 with the distance sensor 20 and collates the obtained measurement result with the 3D CAD model of the workpiece to thereby determine the three-dimensional position and posture of each workpiece. Recognize

  Compared with the image processing system bulk picking device using a camera, this bulk picking device can handle (1) a complex shape as a workpiece, and (2) when the workpiece is tilted, the overlapping In this case, it is possible to take out stably even when foreign matter is mixed.

FIG. 2 is a configuration diagram of the robot hand of FIG.
In this example, the robot hand 24 is an air suction type having a suction pad 24a at the lower end, and picks up the central plane portion of the work 1 to take out the work.
Furthermore, the robot hand 24 or the hand control device 25 includes a suction device (not shown) and a grip detection device (not shown).
The suction device sucks air from the inside of the suction pad 24a to reduce the pressure. The grip detection device detects a state in which the work is attracted to the suction pad 24a (referred to as “grip state”) from a pressure change inside the suction pad 24a.

In this figure, moving the robot hand 24 toward the work 1 (lowering in the figure) is called “advance”, and conversely moving in the direction away from the work (upward in the figure) is “retreat”. Call.
The target position at which the suction surface (lower surface in the drawing) of the suction pad 24a grips the workpiece is referred to as a “work gripping target position”, and the suction surface (lower surface in the drawing) is above the workpiece gripping target position. The position for waiting away is called the “hand standby position”.

  FIG. 3 is a flowchart showing the work picking method of the present invention. As shown in this figure, the work picking method of the present invention comprises steps S1 to S10. Here, the gripping of the workpiece will be described by an air adsorption type.

  Using the above-described bulk picking device, the workpiece 1 stacked in bulk is three-dimensionally measured by the distance sensor 20, and the obtained measurement result is collated with the 3D CAD model of the workpiece, whereby the three-dimensional position and posture of each workpiece are collated. Then, the workpiece picking operation (gripping operation) of the present invention is started.

  First, the robot hand 24 is moved to the hand standby position (step S1). This movement can be performed at high speed without the possibility of interference with the workpiece.

  Next, suction is started (step S2), the robot hand 24 is advanced to a workpiece gripping target position (hereinafter referred to as a workpiece suction target position) (step S3), and the gripping state (that is, the suctioning state) is confirmed (step S4). . These steps S2, S3, and S4 may be performed continuously or concurrently.

Next, when the suction state is good in step S4 (YES), the robot hand 24 is moved backward to take out the workpiece (step S5), and the suction state is confirmed again (step S6).
If the suction state is good in step S6 (YES), the workpiece has been successfully gripped and taken out even if the workpieces are entangled, and the gripping operation is completed in the present invention.

  If the suction state is not good in step S4 (NO), gripping of the workpiece at the workpiece suction target position has failed, the number of retries is confirmed (step S7), and the set number of retries has not been exceeded (step S7). In the case of NO), the workpiece suction target position is changed (step S8), and the robot hand 24 is advanced until the suction state is reached.

  Steps S4, S7, and S8 are performed continuously without stopping each operation, so even if the workpiece suction target position includes an error, the operation advances without retreating until the suction state is confirmed. The adsorption state can be repeatedly confirmed in step S4.

If the suction state is not good in step S6 (NO), the gripping / unloading of the workpiece has failed due to entanglement or suction failure between the workpieces, and the number of retries is confirmed in the same manner (step S7). If the number has not exceeded (NO), the workpiece suction target position is changed (step S8), and the robot hand 24 is moved again to the workpiece suction target position (step S3).
If the suction state is not good in step S6 (NO), the suction may be temporarily stopped, and then the suction may be started again to perform the retry.

  Steps S6, S7, and S8 are continuously performed without stopping each operation other than the suction, so even if the gripping / unloading of the workpiece fails due to entanglement or suction failure between the workpieces, the suction state Until it is confirmed, the retry can be repeated while changing the workpiece suction target position, and the suction state can be repeatedly confirmed in step S6.

The change amount (change distance) of the workpiece suction target position in step S8 is preferably set so that the forward movement amount exceeds the error of the workpiece suction target position by the set number of retries. Further, in order to be able to operate even if the workpiece stacking state changes during the retry operation, three-dimensional measurement is performed with the sensor 20 in step S8, and the obtained measurement result is compared with the 3D CAD model of the workpiece, You may recognize again the three-dimensional position and attitude | position of an individual workpiece | work.
When the number of retries is exceeded in step S7 (YES), that is, when the advance amount exceeds a predetermined set distance, a suction error is warned as the retry number over (S9) (S10), and the gripping operation is completed.

  According to the work picking method of the present invention described above, the robot hand 24 is moved backward to take out the work (step S5), the suction state is confirmed again (step S6), and if the suction state is not good (NO), Since the workpiece suction target position is changed (step S8) and the robot hand 24 is moved forward until the suction state is reached, even if there are entanglements between the workpieces or suction failure, it is possible to accurately detect a gripping error and retry efficiently. can do.

  Further, the robot hand 24 is advanced to the workpiece suction target position (step S3), the suction state is confirmed (step S4), and if the suction state is not good (NO), the workpiece suction target position is changed (step S8). ) Since the robot hand 24 is moved forward until the gripping state is reached, the workpiece can be gripped in a short time even if the workpiece suction target position includes an error.

  Therefore, since the method of the present invention does not move backward until gripping can be confirmed, the operation is efficient, and accurate gripping errors can be detected. Therefore, the operation rate of the unmanned system is improved and the recovery work by humans is reduced. Even if the workpiece gripping target position includes an error, it can be gripped satisfactorily.

The robot hand 24 described above is an air adsorption type. However, the present invention is not limited to this example. As long as the workpieces 1 can be taken out one by one, an electromagnetic type or a combination of picking with a claw and a proximity sensor may be used. Good.
For example, even when the robot hand is a combination of picking with an electromagnetic type or a claw and a proximity sensor, the robot hand can be similarly applied by simply changing the grip confirmation means.

  In addition, this invention is not limited to embodiment mentioned above, Of course, a various change can be added in the range which does not deviate from the summary of this invention.

It is a whole block diagram of the bulk picking apparatus which performs the work picking method of this invention. It is a block diagram of the robot hand of FIG. It is a flowchart which shows the work picking method of this invention. It is a schematic diagram of the apparatus of patent document 1. FIG. It is a schematic diagram of the apparatus and method of patent document 2. FIG.

Explanation of symbols

1 work, 10 work supply device,
12 container body, 12a outer wall, 12b bottom plate,
14 workpiece moving device, 15 inclined member, 16 vibration device,
20 distance sensor, 21 distance sensor control device,
22 robots, 24 robot hands,
24a suction pad, 25 hand control device,
26 3D object recognition device, 28 Robot control device

Claims (3)

For multiple workpieces stacked in a mess
Advance the robot hand to the workpiece gripping target position, check the gripping state,
If the gripping state is not good, change the workpiece gripping target position and repeat the forward movement without retracting the robot hand until the gripping state is reached ,
When the gripping state is good, the robot hand is retracted to take out the workpiece, and the gripping state is confirmed again.If the gripping state is not good by the confirmation, the workpiece gripping target position is changed, and again, A work picking method in a bulk picking apparatus, wherein the robot hand is moved to a work gripping target position . 3D measurement of the stacked workpieces with a distance sensor, and by comparing the obtained measurement results with the 3D CAD model of the workpiece, the 3D position and orientation of each workpiece are recognized, and then the robot hand is placed on standby. The workpiece picking method in the bulk picking apparatus according to claim 1 , wherein the workpiece picking device moves to a position. 3. The bulk picking according to claim 1, wherein the change amount of the workpiece gripping target position is set so that the advance amount of the robot hand exceeds the error of the workpiece gripping target position by the number of retry times set. Work picking method in an apparatus.

Images