Workpiece holding device, workpiece holding method, program, and control device

Abstract

To suppress a situation that when a work-piece is suctioned and held, the other work-piece is suctioned and held at the same time.SOLUTION: A work-piece holding device comprises: holding means that suctions and holds a work-piece one by one out of a plurality of work-pieces put in a three-dimensional space; first information obtaining means that obtains three-dimensional information about the plurality of work-pieces; candidate calculating means that calculates a plurality of candidate holding points, the points being candidates for holding points for the work-pieces at the time when the holding means holds the work-pieces respectively, on the basis of the three-dimensional information about the plurality of work-pieces obtained by the first information obtaining means; second information obtaining means that obtains information about the other work-pieces existing in a predetermined range respectively out of the candidate holding points for the work-pieces; and control means that selects one candidate holding point of the plurality of candidate holding points, on the basis of the information about the work-pieces obtained by the second information obtaining means, and controls the holding means so that the holding means holds the work-pieces at the selected candidate holding point.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a workpiece holding device for holding a workpiece, a workpiece holding method, a program, and a control device. [Background technology]

[0002] A technique is known in which a workpiece holding point is determined by pattern matching with a previously created 3D model pattern using 3D measurement information of the workpiece (see Patent Document 1). Also known is a technique in which a workpiece's maximum height position is detected based on the 3D measurement information of the workpiece, and the maximum height position is set as the workpiece holding point (see Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2009-128191 A [Patent Document 2] JP 2016-028836 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the technology of Patent Document 1 requires the creation of a 3D model pattern for each workpiece in advance, and therefore cannot handle, for example, a wide variety of workpieces. Also, in the technology of Patent Document 2, for example, if there are other workpieces around the maximum height position, there is a risk that the other workpieces will be sucked in at the same time when the workpiece at the maximum height position is sucked in.

[0005] The present invention has been made to solve such problems, and its main object is to provide a work holding device, a work holding method, a program, and a control device that can prevent other workpieces from being simultaneously sucked in and held when a workpiece is sucked in and held. [Means for solving the problem]

[0006] In order to achieve the above object, one aspect of the present invention is to A holding means for sucking and holding each of a plurality of workpieces placed in a three-dimensional space; A first information acquisition means for acquiring three-dimensional information of the plurality of workpieces; a candidate calculation means for calculating a plurality of holding candidate points which are candidates for holding points of the workpieces when the holding means holds each of the workpieces based on the three-dimensional information of the plurality of workpieces acquired by the first information acquisition means; A second information acquisition means for acquiring information on other works existing within a predetermined range from each of the workpiece holding candidate points; A control means for selecting one of the plurality of holding candidate points based on the information of the workpiece acquired by the second information acquisition means, and controlling the holding means so that the holding means holds the workpiece at the selected holding candidate point; A work holding device comprising: It is. In this aspect, the information on the workpiece is information on the presence or absence of the other workpiece, The control means may select a holding candidate point where no other workpiece is present within the predetermined range from among the plurality of holding candidate points, based on information on the presence or absence of the other workpiece. In this one aspect, the second information acquisition means may generate information indicating that there is another work within a specified range when it determines, based on the three-dimensional information of the multiple workpieces acquired by the first information acquisition means, that there is a maximum point, other than the candidate holding point, within a specified range from the candidate holding point of each of the workpieces, where the height direction coordinate value is a maximum. In this embodiment, the second information acquisition means may generate information indicating that there is another work within the specified range when three-dimensional information of a work within the specified range is cut at a horizontal plane perpendicular to the height direction at multiple different height positions, and a cut surface that is discontinuous exists at at least one of the height positions. In this embodiment, the control means may select one of a plurality of candidate holding points at which no other workpieces are present within the specified range, based on the distance between the candidate holding point and other workpieces outside the specified range. In this embodiment, the information on the workpiece is distance information between each of the holding candidate points and other workpieces within the predetermined range, The control means may select one candidate point to retain from among the plurality of candidate points to retain based on the distance information. In this one aspect, the control means may select, from the plurality of candidate holding points, the candidate holding point having the largest integral value of the distance between the candidate holding point and other workpieces within a predetermined range, based on the distance information. In this one aspect, the candidate calculation means may calculate, based on three-dimensional information of a plurality of workpieces acquired by the first information acquisition means, a maximum point at which the coordinate value in the height direction of the workpiece is maximum as the retention candidate point. In this aspect, the candidate calculation means may determine a local maximum point having an area equal to or larger than a predetermined area as the retaining candidate point from among the retaining candidate points that are the local maximum points. In order to achieve the above object, one aspect of the present invention is to Acquiring three-dimensional information of a plurality of workpieces placed in a three-dimensional space; calculating a plurality of candidate holding points which are candidates for holding points of each workpiece when the holding means sucks and holds each workpiece based on the acquired three-dimensional information of the plurality of workpieces; acquiring information on other works present within a predetermined range from each of the workpiece holding candidate points; A step of selecting one of the plurality of holding candidate points based on the acquired workpiece information, and controlling the holding means so that the holding means holds the workpiece at the selected holding candidate point; A method for holding a workpiece, may be also possible. In order to achieve the above object, one aspect of the present invention is to A process of acquiring three-dimensional information of a plurality of workpieces placed in a three-dimensional space; A process of calculating a plurality of candidate holding points which are candidates for holding points of each workpiece when the holding means sucks and holds each workpiece based on the acquired three-dimensional information of the plurality of workpieces; A process of acquiring information on other works that exist within a predetermined range from the holding candidate point of each of the works; A process of selecting one of the plurality of holding candidate points based on the acquired workpiece information, and controlling the holding means so that the holding means holds the workpiece at the selected holding candidate point; A program that causes a computer to execute may be also possible. In order to achieve the above object, one aspect of the present invention is to A first information acquisition means for acquiring three-dimensional information of a plurality of workpieces placed in a three-dimensional space; a candidate calculation means for calculating a plurality of holding candidate points which are candidates for holding points of the workpieces when the holding means holds each of the workpieces based on the three-dimensional information of the plurality of workpieces acquired by the first information acquisition means; A second information acquisition means for acquiring information on other works existing within a predetermined range from each of the workpiece holding candidate points; A control means for selecting one of the plurality of holding candidate points based on the information of the workpiece acquired by the second information acquisition means, and controlling the holding means so that the holding means holds the workpiece at the selected holding candidate point; A control device comprising: may be also possible. Effect of the Invention

[0007] According to the present invention, it is possible to provide a work holding device, a work holding method, a program, and a control device that can suppress simultaneous suction and holding of another work when suctioning and holding a work. [Brief description of the drawings]

[0008] [Figure 1] 1 is a block diagram showing a schematic system configuration of a work holding device according to an embodiment of the present invention; [Diagram 2]1 is a block diagram showing a schematic system configuration of a control device according to an embodiment of the present invention; [Diagram 3] FIG. 4 is a diagram showing a convex portion of a workpiece. [Figure 4] 11 is a diagram for explaining a method for detecting other workpieces within a predetermined range. FIG. [Diagram 5] 4 is a flowchart showing a flow of a workpiece holding method according to the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] EMBODIMENT 1 Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a schematic system configuration of a work holding device according to this embodiment. The work holding device 1 according to this embodiment can suck, hold, and move workpieces one by one from among a plurality of workpieces arranged in a three-dimensional space. The plurality of workpieces are parts randomly piled up in a box or on a plane. The plurality of workpieces includes parts of any shape, such as a planar shape or a three-dimensional shape.

[0010] The workpiece holding device 1 according to this embodiment includes a robot arm 2, a control device 3, and a three-dimensional vision sensor 4.

[0011] The robot arm 2 is a specific example of a holding means. The robot arm 2 is configured as a multi-joint arm having, for example, a plurality of links 21, joints (wrist joints, elbow joints, shoulder joints, etc.) 22 that rotatably connect the links 21, and an end effector 23 provided at the tip of the links 21 to suck and hold the workpiece.

[0012] Each joint 22 is provided with a rotation sensor such as an encoder that detects rotation information of the joint 22, an actuator such as a servo motor that drives the joint 22, and a force sensor that detects the operating force of the joint 22. The force sensor is, for example, a torque sensor that detects the torque of the joint 22. Each joint 22 is provided with a reduction mechanism, etc.

[0013] The end effector 23 attracts and holds the workpiece in a non-contact manner by using an attractive force such as magnetic force or air pressure. The end effector 23 is configured to, for example, electromagnetically attract the workpiece by generating magnetic force and to release the electromagnetically attracted workpiece by stopping the generation of the magnetic force.

[0014] The control device 3 performs various types of arithmetic processing and control processing for the robot arm 2. The control device 3 has a hardware configuration of a normal computer including, for example, a processor 3a such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit), an internal memory 3b such as a RAM (Random Access Memory) or a ROM (Read Only Memory), a storage device 3c such as an HDD (Hard Disk Drive) or an SSD (Solid State Drive), an input / output I / F 3d for connecting peripheral devices such as a display, and a communication I / F 3e for communicating with devices outside the device.

[0015] The three-dimensional vision sensor 4 is a specific example of a first information acquisition means. The three-dimensional vision sensor 4 acquires three-dimensional information of a plurality of workpieces. The three-dimensional information of the workpieces includes information on the shape, position (three-dimensional coordinates, etc.), and posture of each workpiece.

[0016] The three-dimensional vision sensor 4 is provided, for example, on the end effector 23 or link 21 of the robot arm 2. The three-dimensional vision sensor 4 is composed of a camera, a laser sensor, etc. The three-dimensional vision sensor 4 outputs the acquired three-dimensional information of the workpiece to the control device 3.

[0017] 2 is a block diagram showing a schematic system configuration of the control device according to this embodiment. The control device 3 according to this embodiment has a candidate calculation unit 31, a work information acquisition unit 32, and a robot control unit 33.

[0018] The candidate calculation unit 31 is a specific example of a candidate calculation means. Based on the three-dimensional information of the workpiece acquired by the three-dimensional vision sensor 4, the candidate calculation unit 31 calculates a plurality of candidate holding points that are candidates for holding points (suction points) of the workpiece when the end effector 23 of the robot arm 2 sucks and holds the workpiece.

[0019] For example, the candidate calculation unit 31 calculates depth information indicating the height position of each workpiece based on the three-dimensional information of the workpiece acquired by the three-dimensional vision sensor 4. The candidate calculation unit 31 detects convex parts protruding in the height direction based on the calculated depth information of each workpiece (FIG. 3).

[0020] The candidate calculation unit 31 performs binarization based on the calculated depth information, for example, by setting points at or above a predetermined height as 1 and points below the predetermined height as 0, and detects points that are 1 as convex parts. The candidate calculation unit 31 may set the convex parts detected as described above as holding candidate points. This allows convex parts that are easy for the end effector 23 to suck and hold to be set as holding candidate points.

[0021] Furthermore, the candidate calculation unit 31 may set as a holding candidate point, from among the detected convex parts, a convex part having an end face area for suction by the end effector 23 equal to or greater than a threshold value. This makes it possible to narrow down, from among the convex parts that are easy for the end effector 23 to suction and hold, points having a large suction area and therefore easier to suction and hold, as holding candidate points.

[0022] The candidate calculation unit 31 may calculate, as a holding candidate point, a maximum point where the coordinate value of the workpiece in the height direction is maximum, based on the three-dimensional information of the workpiece acquired by the three-dimensional vision sensor 4. This allows a maximum point that protrudes greatly in the height direction and is easy for the end effector 23 to suck and hold to be set as a holding candidate point.

[0023] Furthermore, the candidate calculation unit 31 may set local maximum points having a predetermined area or more as holding candidate points from among the holding candidate points that are the above-mentioned local maximum points. This makes it possible to narrow down the holding candidate points to points having a large suction area and easier to be attracted and held by the end effector 23 from among the local maximum points that are easy to be attracted and held by the end effector 23.

[0024] The candidate calculation unit 31 may further determine whether or not the workpiece can be held at each of the candidate holding points narrowed down as described above, based on the three-dimensional information of the workpiece acquired by the three-dimensional vision sensor 4. The candidate calculation unit 31 may determine whether or not the workpiece can be held by determining whether or not there is interference with another workpiece when the workpiece is held at each candidate holding point. The candidate calculation unit 31 may set the candidate holding points determined to be capable of being held as the final multiple candidate holding points.

[0025] The candidate calculation unit 31 outputs the plurality of retention candidate points calculated as described above to the robot control unit 33.

[0026] However, in a conventional workpiece holding device, when sucking in and holding a workpiece at a candidate holding point, there is a risk that other workpieces in the vicinity will be sucked in at the same time.

[0027] In contrast, the work holding device 1 of this embodiment acquires information on other workpieces that are present within a predetermined range from the candidate holding point of each workpiece, selects one of the multiple candidate holding points based on the acquired information on the other workpieces, and controls the robot arm 2 so that the robot arm 2 holds the workpiece at the selected candidate holding point.

[0028] This allows a candidate holding point that is unlikely to simultaneously attract other workpieces to be selected in consideration of the state of other workpieces around the candidate holding point for each workpiece, and the workpiece can be held at that candidate holding point. Therefore, when sucking and holding a workpiece, it is possible to prevent sucking and holding other workpieces at the same time.

[0029] The workpiece information acquisition unit 32 is a specific example of a second information acquisition means. The workpiece information acquisition unit 32 acquires information on other works that exist within a predetermined range from the holding candidate point of each workpiece (hereinafter, other workpiece information).

[0030] The predetermined range is set in advance in the workpiece information acquisition unit 32. The predetermined range is a range that is affected by the attractive force (magnetic force, etc.) of the end effector 23, and is set based on the attractive force. The predetermined range is set, for example, by taking into account a buffer in addition to the height at which the end effector 23 attracts the workpiece or another workpiece when the end effector 23 approaches a candidate holding point for the workpiece.

[0031] The other work information is, for example, information indicating whether or not other works exist within a predetermined range (presence or absence).

[0032] The work information acquiring unit 32 may determine whether or not there is a maximum point, other than the holding candidate point, whose coordinate value in the height direction is a maximum, within a predetermined range from the holding candidate point of each work, based on the three-dimensional information of the multiple workpieces acquired by the three-dimensional vision sensor 4. When determining that there is a maximum point other than the holding candidate point within the predetermined range, the work information acquiring unit 32 may generate information indicating that another workpiece is present within the predetermined range.

[0033] If there is another workpiece within the specified range, that workpiece will have a maximum point that protrudes in the height direction, and by detecting that maximum point as described above, other workpieces within the specified range can be easily detected.

[0034] The work information acquiring unit 32 may also determine whether or not there is a cut surface that is discontinuous at at least one height position when the three-dimensional information of the work within the predetermined range is cut at a horizontal plane perpendicular to the height direction at a plurality of different height positions. When it is determined that there is a cut surface that is discontinuous at at least one height position, the work information acquiring unit 32 may generate information indicating that there is another work within the predetermined range.

[0035] If other workpieces exist within the specified range, there will be other piles of workpieces in the height direction (Z direction) other than the pile of workpieces that includes the candidate holding point. Therefore, when the pile of workpieces is cut with a horizontal plane perpendicular to the height direction, the cut surface will be discontinuous. By detecting such discontinuous cross sections, other workpieces within the specified range can be detected easily and with high accuracy.

[0036] For example, as shown in Figure 4(a), when the workpiece is cut at the height position of the first layer, only the peak of workpiece A that includes the candidate holding point is cut, so the cut surface includes only the cut surface of workpiece A and is continuous.

[0037] Next, if the workpiece is cut at a height position of the second layer, which is lower than the first layer, the cut will be made in the middle of the pile of workpiece A that includes the candidate holding point and in the middle of the pile of other workpiece B, and the cut surface will be discontinuous, including the cut surface of workpiece A and the cut surface of other workpiece B.

[0038] Furthermore, if the workpiece is cut at a height position of the third layer, which is lower than the second layer, the pile of workpiece A including the candidate holding point and the pile of other workpiece B will be cut, so the cut surface will include the cut surface of workpiece A and the cut surface of other workpiece B, but since workpiece A and other workpiece B overlap, the cut surface will be continuous.

[0039] In this way, when other workpieces exist within the predetermined range, if the workpiece is cut at gradually changing height positions on a horizontal plane perpendicular to the height direction, a cut surface that is discontinuous will exist at at least one height position. By detecting this discontinuous cut surface, other workpieces within the predetermined range can be simply and easily detected.

[0040] The number of cuts and the interval between cuts can be set arbitrarily. For example, if the number of cuts is increased and the interval between cuts is decreased, the accuracy of the determination of the presence or absence of the other workpiece is improved, but the amount of calculation increases accordingly. Therefore, it is preferable to set the optimal number of cuts and the interval between cuts by taking into consideration the accuracy of the determination of the presence or absence of the other workpiece and the amount of calculation.

[0041] The workpiece information acquisition unit 32 outputs the workpiece information indicating the presence or absence of other workpieces acquired as described above to the robot control unit 33.

[0042] The robot control unit 33 is a specific example of a control means. The robot control unit 33 controls the operation of the robot arm 2. For example, the robot control unit 33 performs feedback control of the robot arm 2 by controlling the actuator of each joint based on rotation information (rotation angle, etc.) from a rotation sensor of each joint and an operating force from a force sensor. The robot control unit 33 also controls the attraction force of the end effector 23 to control the attraction and release of the workpiece by the end effector 23. In this way, the robot control unit 33 can hold and move the workpiece by controlling the robot arm 2.

[0043] The robot control unit 33 selects one holding candidate point from the multiple holding candidate points calculated by the candidate calculation unit 31.

[0044] The robot control unit 33 controls the robot arm 2 based on the three-dimensional information of the workpiece acquired by the three-dimensional vision sensor 4 so that the end effector 23 of the robot arm 2 holds the workpiece at the holding candidate point.

[0045] The robot control unit 33 selects a candidate holding point where no other workpieces exist within a predetermined range from among a plurality of candidate holding points, based on the workpiece information indicating the presence or absence of other workpieces from the workpiece information acquisition unit 32. This makes it possible to select a candidate holding point where no other workpieces exist in the vicinity, and by suctioning and holding the workpiece at that candidate holding point, it is possible to prevent other workpieces from being sucked in and held at the same time.

[0046] Here, when there are multiple candidate holding points where no other workpieces exist within a predetermined range, the robot control unit 33 narrows down the candidate holding points. For example, the robot control unit 33 selects one candidate holding point from multiple candidate holding points where no other workpieces exist within a predetermined range, based on the distance between the other workpieces outside the predetermined range and the candidate holding point. This makes it possible to select an optimal candidate holding point that is difficult to simultaneously suck in other workpieces outside the predetermined range and can suck in and hold only the workpiece to be held, taking into account the distance between the other workpieces outside the predetermined range and the candidate holding point.

[0047] The robot control unit 33 may select a candidate holding point that is the largest distance away from other workpieces outside the predetermined range from among a plurality of candidate holding points where no other workpieces exist within a predetermined range.

[0048] As a result, after narrowing down the candidate holding points to those where no other workpieces exist within a predetermined range, it is possible to further select from the narrowed down candidate holding points the candidate holding point that is the furthest away from other workpieces outside the predetermined range and the least likely to attract other workpieces outside the predetermined range. Therefore, when sucking and holding a workpiece at that candidate holding point, it is possible to more reliably prevent other workpieces from being sucked and held at the same time.

[0049] For example, the robot control unit 33 selects one candidate holding point by using an evaluation function related to the distance between the candidate holding point and another workpiece outside a predetermined range.

[0050] This evaluation function may be defined as the inverse of the distance between the holding candidate point and other workpieces outside the predetermined range, so that the evaluation value decreases as the distance between the holding candidate point and other workpieces outside the predetermined range increases.

[0051] The distance between the candidate holding point and other workpieces outside the specified range is, for example, the integral value of the distance between the suction holding surface (tool bottom surface) of the end effector 23 when holding the workpiece at the candidate holding point and other workpieces outside the specified range. When the suction holding surface of the end effector 23 is brought closer to the candidate holding point of the workpiece to be held in order to suck and hold the workpiece at the candidate holding point, the other workpieces closer to the suction holding surface of the end effector 23 are more affected by the suction force, so the above distance is calculated.

[0052] Therefore, it is preferable to select the candidate holding point for which the integral value of the distance between the candidate holding point and other workpieces outside the specified range, i.e., the distance between the suction holding surface of the end effector 23 and other workpieces outside the specified range, is the largest and the above evaluation value is the smallest.

[0053] For example, the evaluation function J is defined as follows:

number

[0054] (u, v) is the position of a point (pixel) in a depth image. u is the abscissa value and v is the ordinate value. For example, if the image is 640x480, u and v are 0≦u<640 and 0≦v<480, respectively.

[0055] d(u, v) is the depth value of the depth image at point (u, v). Specifically, depth is the distance from the camera (3D vision sensor 4) to the object being photographed, and is expressed in meters and takes a non-negative value. However, the value 0 is special, and means that the camera was unable to obtain the depth of the object at that position.

[0056] There are various reasons why image capture may not be possible, but the most common is when the direction of the camera's light source is different from the direction in which the light hits the subject and is reflected back to the camera's sensor, causing the light to be blocked by an obstacle and not reflected back.

[0057] d tis the depth at the holding candidate point currently being focused on. D is the distance over which the suction force acts downward from the holding candidate point. Δ is the threshold of the cut-off height set to binarize the depth image, and d t from d t to d

[0058] Ω0 is the set of points in the depth image where the depth could not be obtained as described above. Ω t is the set of points that are in the same region (within a predetermined region) as the holding candidate point and where the depth is less than dt + D (closer to the camera), that is, d(u, v) < dt + D.

[0059] Note that in the above evaluation function J, by dividing by the total number of pixels excluding the mountains including the holding candidate points and the holes with depth = 0, the influence per effective pixel is normalized.

[0060] As described above, the robot control unit 33 calculates an evaluation value calculated by taking the sum over all points that are not in the same region (outside the predetermined region) as the currently focused holding candidate point and where 0 < d(u, v) < dt + D using the evaluation function J.

[0061] Subsequently, the work holding method according to the present embodiment will be described. FIG. 5 is a flowchart showing the flow of the work holding method according to the present embodiment. Note that the control process shown in FIG. 5 is repeatedly executed every predetermined time.

[0062] The three-dimensional vision sensor 4 acquires the three-dimensional information of the work and outputs it to the control device 3 (step S101).

[0063] The candidate calculation unit 31 of the control device 3 calculates a plurality of holding candidate points of the end effector 23 of the robot hand based on the three-dimensional information of the work acquired by the three-dimensional vision sensor 4 (step S102).

[0064] The workpiece information acquisition unit 32 acquires other workpiece information of each of the other workpieces that exist within a predetermined range from the holding candidate point of each workpiece calculated by the candidate calculation unit 31 (step S103).

[0065] The robot control unit 33 selects one holding candidate point from among the multiple holding candidate points based on the other workpiece information from the workpiece information acquisition unit 32 (step S104).

[0066] The robot control unit 33 controls the robot arm 2 so that the end effector 23 of the robot arm 2 holds the workpiece at the selected candidate holding point (step S105).

[0067] As described above, the work holding device 1 according to this embodiment acquires information on other workpieces that are present within a predetermined range from the candidate holding point of each workpiece, selects one of the multiple candidate holding points based on the acquired information on the other workpieces, and controls the robot arm 2 so that the robot arm 2 holds the workpiece at the selected candidate holding point.

[0068] This allows other workpieces around the candidate holding point of each workpiece to be taken into consideration, and allows the selection of a candidate holding point that is unlikely to simultaneously suck in and hold another workpiece, and allows the workpiece to be sucked in and held at that candidate holding point. Therefore, when sucking in and holding a workpiece, it is possible to prevent the sucking in and holding of another workpiece at the same time.

[0069] EMBODIMENT 2 In this embodiment, the work information may be distance information between each holding candidate point and other workpieces within a predetermined range. The work information acquisition unit 32 acquires distance information between each holding candidate point and other workpieces within a predetermined range based on the three-dimensional information of the multiple workpieces acquired by the three-dimensional vision sensor 4.

[0070] The robot control unit 33 selects one holding candidate point from the multiple holding candidate points calculated by the candidate calculation unit 31 based on distance information between each holding candidate point acquired by the work information acquisition unit 32 and other workpieces within a specified range.

[0071] This allows a candidate point for holding a workpiece to be selected that is unlikely to simultaneously attract other workpieces, taking into consideration the distance between the candidate point for holding each workpiece and other surrounding workpieces, and allows the workpiece to be attracted and held at that candidate point. Therefore, when attracting and holding a workpiece, it is possible to prevent the attracting and holding of other workpieces at the same time.

[0072] For example, the robot control unit 33 may select a holding candidate point having the largest integral value of the distance between the holding candidate point and other workpieces within a predetermined range from among the multiple holding candidate points calculated by the candidate calculation unit 31, based on distance information between each holding candidate point and other workpieces within a predetermined range acquired by the workpiece information acquisition unit 32. This makes it possible to select a holding candidate point having the largest distance between the holding candidate point of each workpiece and other surrounding workpieces, making it less likely to simultaneously suck in other workpieces.

[0073] For example, the robot control unit 33 may select a holding candidate point for which the evaluation value of the evaluation function J regarding the distance between the holding candidate point and other workpieces within a predetermined range is the smallest.

[0074] For example, the present invention can also be realized by causing a processor to execute a computer program to perform the processing shown in FIG.

[0075] The program can be stored and provided to a computer using various types of non-transitory computer readable media. The non-transitory computer readable media includes various types of tangible storage media. Examples of the non-transitory computer readable media include magnetic recording media (e.g., flexible disks, magnetic tapes, hard disk drives), magneto-optical recording media (e.g., magneto-optical disks), CD-ROMs (Read Only Memory), CD-Rs, CD-R / Ws, and semiconductor memories (e.g., mask ROMs, PROMs (Programmable ROMs), EPROMs (Erasable PROMs), flash ROMs, and RAMs (random access memories)).

[0076] The program may be provided to the computer by various types of transitory computer readable media. Examples of the transitory computer readable medium include an electric signal, an optical signal, and an electromagnetic wave. The transitory computer readable medium can provide the program to the computer via a wired communication path such as an electric wire and an optical fiber, or via a wireless communication path.

[0077] Each unit constituting the control device 3 according to each of the above-mentioned embodiments can be realized not only by a program, but also in whole or in part by dedicated hardware such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array). [Explanation of symbols]

[0078] 1 workpiece holding device, 2 robot arm, 3 control device, 4 three-dimensional vision sensor, 21 link, 22 joint section, 23 end effector, 31 candidate calculation section, 32 workpiece information acquisition section, 33 robot control section

Claims

1. A holding means for sucking and holding a workpiece one by one from among a plurality of workpieces placed in a three-dimensional space; A first information acquisition means for acquiring three-dimensional information of the plurality of workpieces; a candidate calculation means for calculating a plurality of holding candidate points which are candidates for holding points of the workpieces when the holding means holds each of the workpieces based on the three-dimensional information of the plurality of workpieces acquired by the first information acquisition means; A second information acquisition means for acquiring information on other works existing within a predetermined range from each of the workpiece holding candidate points; A control means for selecting one of the plurality of holding candidate points based on the information of the workpiece acquired by the second information acquisition means, and controlling the holding means so that the holding means holds the workpiece at the selected holding candidate point; Equipped with The information on the workpiece is information on the presence or absence of the other workpiece, The control means selects a retention candidate point where no other workpiece is present within the predetermined range from among the plurality of retention candidate points based on information on the presence or absence of the other workpiece, The second information acquisition means generates information indicating that another workpiece is present within the predetermined range when the three-dimensional information of the workpiece within the predetermined range is cut at a plurality of different height positions along a horizontal plane perpendicular to the height direction and a cut surface that is discontinuous at at least one of the height positions exists. Work holding device.

2. The workpiece holding device according to claim 1, The control means selects one holding candidate point from among a plurality of holding candidate points where no other workpieces are present within the predetermined range, based on a distance between the holding candidate point and other workpieces outside the predetermined range. Work holding device.

3. The workpiece holding device according to claim 1, The information on the workpiece is distance information between each of the retention candidate points and other workpieces within the predetermined range, The control means selects one retention candidate point from among the plurality of retention candidate points based on the distance information. Work holding device.

4. The workpiece holding device according to claim 1, The candidate calculation means calculates a maximum point, at which a coordinate value in a height direction of the workpiece is a maximum, as the holding candidate point based on the three-dimensional information of the plurality of workpieces acquired by the first information acquisition means. Work holding device.

5. A step in which a first information acquisition means acquires three-dimensional information of a plurality of workpieces placed in a three-dimensional space; A step in which a candidate calculation means calculates a plurality of holding candidate points which are candidates for holding points of each workpiece when the holding means sucks and holds each workpiece, based on the acquired three-dimensional information of the plurality of workpieces; A step in which a second information acquisition means acquires information on other works that exist within a predetermined range from the holding candidate point of each of the works; A step of controlling the holding means to select one of the plurality of holding candidate points based on the acquired workpiece information, and to control the holding means so that the holding means holds the workpiece at the selected holding candidate point; Including, The information on the workpiece is information on the presence or absence of the other workpiece, The control means selects a retention candidate point where no other workpiece is present within the predetermined range from among the plurality of retention candidate points based on information on the presence or absence of the other workpiece, The second information acquisition means generates information indicating that another workpiece is present within the predetermined range when the three-dimensional information of the workpiece within the predetermined range is cut at a plurality of different height positions along a horizontal plane perpendicular to the height direction and a cut surface that is discontinuous at at least one of the height positions exists. Workpiece holding method.

6. A process of acquiring three-dimensional information of a plurality of workpieces placed in a three-dimensional space; A process of calculating a plurality of candidate holding points which are candidates for holding points of each workpiece when the holding means sucks and holds each workpiece based on the acquired three-dimensional information of the plurality of workpieces; A process of acquiring information on other works that exist within a predetermined range from the holding candidate point of each of the works; A process of selecting one of the plurality of holding candidate points based on the acquired workpiece information, and controlling the holding means so that the holding means holds the workpiece at the selected holding candidate point; Run the following on your computer: The information on the workpiece is information on the presence or absence of the other workpiece, Based on the information on the presence or absence of other workpieces, a retention candidate point where no other workpieces are present within the predetermined range is selected from among the plurality of retention candidate points; When the three-dimensional information of the workpiece within the predetermined range is cut at a plurality of different height positions on a horizontal plane perpendicular to the height direction, if there is a cut surface that is discontinuous at at least one of the height positions, information is generated indicating that another workpiece is present within the predetermined range. program.

7. A first information acquisition means for acquiring three-dimensional information of a plurality of workpieces placed in a three-dimensional space; a candidate calculation means for calculating a plurality of holding candidate points which are candidates for holding points of the workpieces when the holding means holds each of the workpieces based on the three-dimensional information of the plurality of workpieces acquired by the first information acquisition means; A second information acquisition means for acquiring information on other works existing within a predetermined range from each of the workpiece holding candidate points; A control means for selecting one of the plurality of holding candidate points based on the information of the workpiece acquired by the second information acquisition means, and controlling the holding means so that the holding means holds the workpiece at the selected holding candidate point; Equipped with The information on the workpiece is information on the presence or absence of the other workpiece, The control means selects a retention candidate point where no other workpiece is present within the predetermined range from among the plurality of retention candidate points based on information on the presence or absence of the other workpiece, The second information acquisition means generates information indicating that another workpiece is present within the predetermined range when the three-dimensional information of the workpiece within the predetermined range is cut at a plurality of different height positions along a horizontal plane perpendicular to the height direction and a cut surface that is discontinuous at at least one of the height positions exists. Control device.

Images