WORKPIECE REMOVAL DEVICE, WORKPIECE REMOVAL METHOD AND CONTROL DEVICE

Abstract

A device for removing workpieces, a method for removing workpieces, and a control device for efficiently removing workpieces from a container are presented.The workpiece removal device is equipped with: a robot equipped with a hand for removing a workpiece from a container; a shape-fixing unit for fixing the shape of the hand, the container, and the workpiece; a sensor configured to detect the container and the workpiece within it; a removal position / position determination unit for determining a removal position and a removal position for the hand when the detected workpiece is removed by hand; a locking unit for determining an intermediate position in which the hand is located above and inside the container, and in which the hand's position becomes the removal position when the removal process of the detected workpiece is carried out; and an operating control unit to cause the hand to move from the intermediate position to the removal position solely by a translational movement.

Description

TECHNICAL AREA

[0001] Embodiments of the present invention relate to a workpiece picking device, a method for picking up workpieces and a control device. STATE OF THE ART

[0002] A device is known from the prior art that is configured to detect the positions and orientations of randomly stacked workpieces and picks up an identified workpiece using a robot. Such a device is known in which randomly stacked workpieces are detected by a camera to obtain a two-dimensional image, or in which the workpieces are measured by a three-dimensional measuring instrument to obtain a set of three-dimensional points, and in which the position of the item is identified by pattern matching using the two-dimensional image or the set of three-dimensional points (see, for example, patent documents 1 and 2).

[0003] Also known is a device for picking up objects which is configured to identify the positions and orientations of randomly stacked workpieces using various three-dimensional measuring instruments without performing a pattern comparison, and picks up the identified workpieces (see e.g. patent document 3). Patent document 1: Japanese patent application disclosure JP 2004-295 223 A Patent document 2: Japanese patent application disclosure JP 2011-179 909 A Patent Document 3: Japanese Patent Application Publication JP 2015-089 590 A BRIEF DESCRIPTION OF THE INVENTION Problems to be solved with the invention

[0004] Several workpieces randomly stacked in a container are in different positions. To pick up the workpieces with a robot, it is necessary to tilt a hand attached to the robot according to the workpiece's position. However, if the hand's position is changed immediately before picking up the workpiece, it could damage the container and / or other workpieces in the vicinity.

[0005] There are various methods for detecting obstacles that could hinder a robot using an optical 3D sensor. However, the optical sensor can only detect surface information about the upper part of the container, and the 3D optical sensor may not be able to detect 3D data at all. Therefore, it is difficult to reliably predict and avoid obstructions using optical sensors.

[0006] Furthermore, a technology for automatic path generation has been proposed to determine a robot's trajectory in such a way that the robot does not interfere with its surroundings. However, implementing such a technology requires a powerful processing unit and considerable processing time. Means of solving the problems

[0007] One aspect of the present invention is a workpiece picking device comprising: a robot with a hand configured to pick up a workpiece in a container; a shape-locking unit configured to lock the shapes of the hand, the container, and the workpiece; a sensor configured to detect the container and the workpiece within the container; a pick-up position / pick-up attitude locking unit configured to determine a pick-up position and a pick-up attitude of the hand when the hand picks up a detected workpiece; a pick-up position locking unit configured to determine an intermediate position where the hand is positioned above and inside the container, and where the position of the hand represents the pick-up attitude when the hand performs an operation to pick up the detected workpiece;and an operational control unit configured to move the hand from the intermediate position to the picking position only by means of a translational movement.

[0008] Another aspect of the present invention is a method for picking up workpieces using a robot with a hand configured to pick up a workpiece in a container, the method comprising the following steps: defining the shapes of the hand, the container, and the workpiece; detecting the container and the workpiece within the container; determining a picking position and a picking position of the hand when the hand picks up a detected workpiece; determining an intermediate position in which the hand is positioned above and within the container and in which the position of the hand represents the picking position when the hand performs an operation to pick up the detected workpiece; and moving the hand from the intermediate position to the picking position solely by a translational movement.

[0009] Another aspect of the present invention is a controller for a robot with a hand configured to pick up a workpiece in a container, and for a sensor configured to detect the container and the workpiece in the container, wherein the controller comprises: a shape-locking unit configured to lock the shapes of the hand, the container, and the workpiece; a pick-up position / pick-up attitude locking unit configured to determine a pick-up position and a pick-up attitude of the hand when the hand picks up a detected workpiece; a pick-up attitude locking unit configured to determine an intermediate position at which the hand is positioned above and inside the container, and at which the position of the hand represents the pick-up attitude when the hand performs an operation to pick up the detected workpiece;and an operations control unit configured to move the hand from the intermediate position to the grasping position only by means of a translational movement. Effect of the invention

[0010] According to the present invention, the intermediate position is located above and inside the container, and the hand does not change its position after reaching the intermediate position, approaching the object to be grasped only by a translational movement. Therefore, an efficient gripping process can be carried out without the hand affecting the container or other workpieces. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a schematic configuration view of a workpiece gripping device according to one embodiment; Fig. 2 is a flowchart showing an example of a hiring process; Fig. Figure 3 is a flowchart showing an example of a process for picking up workpieces, and Fig. Figure 4 is a schematic view of an example of a hand movement path. DESCRIPTION OF THE EXECUTION FORMS

[0011] Fig. Figure 1 is a schematic configuration view of a workpiece gripping device according to a preferred embodiment. The workpiece gripping device 10 includes at least one robot 12, a three-dimensional sensor 14, and a controller 16 which is wirelessly or wired connected to the robot 12 and the sensor 14 and is configured to control the robot 12 and the sensor 14.

[0012] For example, robot 12 is an industrial articulated robot with a serial connection structure and has a base 18 installed at a predetermined location, such as a factory production line, a rotary body 20 rotatably attached to the base 18, a first arm (upper arm) 22 rotatably attached to the rotary body 20, a second arm (lower arm) 24 rotatably attached to the first arm 22, a wrist section (mechanical interface) 26 rotatably attached to the second arm 24, and a robot hand 28 attached to the wrist section 26. Robot 12 is configured to pick up one workpiece 32 after another, which are randomly stacked in a container 30.

[0013] In this embodiment, the three-dimensional sensor 14 is configured to detect the position of the container 30 and the workpiece 32 within the container 30 based on instructions from the controller 16. For example, a stereo camera can be used that is configured to detect the three-dimensional position based on the parallax of the images captured by two two-dimensional cameras, or a TOF (Time of Flight) camera that is configured to detect a distance image using an optical time-of-flight method.

[0014] The robot 12 is configured to perform various operations, such as picking up a workpiece based on a command transmitted by the controller 16. The controller 16 includes a processor and a memory unit (memory, etc.) and can control the robot 12 and the sensor 14, which detects the container 30 and the workpieces 32 inside the container 30.In this embodiment, the processor of the robot controller 16 has the functions of a shape-locking unit for locking the shapes of the hand 28, the container 30, and the workpiece 32; a pick-up position / pick-up position locking unit for determining the pick-up position and pick-up position of the hand 28 when the hand 28 picks up the detected workpiece 32; a pick-up position locking unit for determining an intermediate position (described later) in which the hand 28 is positioned above and inside the container 30 and in which the position of the hand 28 represents the pick-up position when the hand 28 performs a pick-up operation on the detected workpiece 32; and an operating control unit for moving the hand 28 from the intermediate position to the pick-up position by a purely translational movement. However, the present invention is not limited as such. For example,A computer (not shown), such as a personal computer (PC), which is connected to the controller 16 either wired or wirelessly and has a processor and a storage unit (memory, etc.), can generate a motion program of the robot so that the generated program can be transferred from the computer to the controller 16.

[0015] Fig. Figure 2 is a flowchart showing an example of a process to be carried out as a setup before the actual picking up of the workpieces 32 by the workpiece pick-up device 10. First, in step S1, the shape and size of the container 30, in which the workpieces 32 are randomly stacked, are defined. Next, in step S2, the shape and size of the robot hand 28 and the position of an intermediate point, such as a tool center point (TCP), are defined.

[0016] Next, in step S3, the shape and size of the workpiece 32 are defined. Finally, in step S4, the picking position and orientation of the hand 28 relative to the workpiece 32 are set; that is, the position and orientation of the hand 28 relative to the workpiece 32 when the hand 28 picks up the workpiece 32. It should be noted that the settings in steps S1 to S4 can be made by a user via an input device (not shown), such as a suitable user interface, or can be performed automatically by the controller 16 or a processor of another computer based on 3D models of the container, the hand, and the workpiece, etc.

[0017] Fig. Figure 3 is a flowchart showing an example of a process in which the workpiece 32 is picked up by the workpiece gripper 10. First, in step S11, 3D data of the container 30 and the workpiece 32 inside the container 30 are detected. Specifically, this involves image data or a three-dimensional point cloud of the container 30 and the workpiece 32, acquired using the sensor 14.

[0018] Next, in step S12, the position of container 30 is determined. Specifically, the position of container 30 is determined based on a procedure such as model matching using the 3D data of container 30 obtained in step S11 and the shape and size of container 30 defined in step S1 described above.

[0019] Next, in step S13, the position of workpiece 32 in container 30 is determined. More precisely, the position of workpiece 32 is determined similarly to step S12, based on a method such as model matching, using the 3D data of workpiece 32 obtained in step S11 and the shape and size of workpiece 32 defined in step S3 described above. At this point, the orientation of workpiece 32 can also be determined.

[0020] Next, in step S14, the picking position and picking orientation of hand 28 relative to workpiece 32 are determined. Specifically, based on the position (or position and orientation) of workpiece 32 determined in step S13 and the picking position and picking orientation of hand established in step S4 described above, the picking position and picking orientation of hand 28 when picking up the identified workpiece 32 are determined.

[0021] Next, in step S15, an intermediate position is determined that the hand 28 must pass through before reaching the picking position determined in step S14. In this embodiment, the intermediate position is a position through which the hand 28 (or the intermediate points thereof, etc.) must pass before reaching the workpiece 32 to be picked up, and at the intermediate position, the hand 28 is positioned above and inside the container 30 while assuming the picking position as described above. Here, "above ... the container" refers to a space vertically above an upper end 38 of the container 30, as shown in Fig. 1 shown, and “within the container” to a space obtained by pushing the opening of the container 30 vertically upwards, as indicated by the reference sign 40 in Fig. 1 shown.

[0022] One specific method for calculating the intermediate position might involve using CAD data of hand 28 to determine whether or not there is an obstruction between hand 28 and container 30 or workpiece 32. However, since a robot hand typically has a complex shape, calculations using CAD data are accurate, but processing the calculations can be very time-consuming.

[0023] Therefore, the shape of hand 28 can, for example, be approximated to a basic shape containing at least one sphere, cylinder, polygonal prism, or polyhedron, and the intermediate position can be determined such that a significant portion of the basic shape is positioned above and inside container 30. Alternatively, a convex hull (convex polyhedron) containing hand 28 can be determined from the CAD data, and the intermediate position can be determined such that each vertex of the convex hull is positioned above and inside container 30. In either case, the computation time can be significantly reduced compared to using CAD data.

[0024] Furthermore, in step S15 there may be cases where the intermediate position that fulfills the aforementioned condition (the intermediate position lies above and inside the container) cannot be calculated or determined for the workpiece to be removed. In this case, it can be assumed that there was a problem with which workpiece should be picked up, so it is preferable not to pick up the workpiece that was intended for picking up and to repeat the process by picking up a different workpiece.

[0025] Next, in step S16, hand 28 is moved to the intermediate position determined in step S15. The robot 12 is controlled so that, upon reaching the intermediate position, hand 28 assumes the grasping position defined in step S14. For example, if, as in Fig. As shown in Figure 1, the approach direction of the hand 28 relative to the workpiece 32 to be picked up is the z-direction of a coordinate system 34 set for the workpiece 32, the hand 28 presents the picking position at the intermediate position such that the z-direction of a coordinate system 36 set for the hand 28 is parallel to the z-direction of the coordinate system 34.

[0026] Next, in step S17, hand 28 is moved (translationally moved) from the intermediate position to the workpiece's picking position. As in Fig. As shown in Figure 1, the hand 28 moves, for example, from the intermediate position to the workpiece 32 to be picked up along a path of movement 42 without changing its position. It should be noted that the path of movement from the intermediate position to the workpiece to be picked up can be a simple straight line or can contain straight lines in different directions connected by at least one bending point, as shown in Figure 1. Fig. 1 shown, or at least may contain a partial curve.

[0027] Finally, in step S18, the workpiece 32 to be picked up is grasped by hand 28 by gripping or suction, etc. When picking up another workpiece, the steps S11 to S18 mentioned above are repeated.

[0028] Fig.Figure 4 is a schematic view illustrating an example of a method for determining the intermediate position. If a workpiece 32a is identified as the target to be grasped and the intermediate position is determined such that the hand 28 moves from the intermediate position to the workpiece 32a along a single straight line (path of movement) 44, another workpiece 32b may interfere with the hand 28. To grasp the workpiece 32a, however, the hand 28 must move along the straight line 44, at least in the immediate vicinity of the workpiece 32a.

[0029] By determining the intermediate position such that the hand 28 moves along a path of movement that is a certain distance away from the workpiece 32a to be picked up and has an upwardly displaced part, it is therefore possible to pick up the workpiece 32a to be picked up and at the same time reliably avoid interference with the other workpieces 32b, as reference numeral 46 shows.

[0030] According to the embodiment described above, the intermediate position is located above and inside the container 30, and the hand 28 does not change its position after the intermediate position, approaching the target to be picked up only by a translational movement. Therefore, the hand 28 does not interfere with the container 30 or the other workpieces 32 and can carry out the picking process smoothly. REFERENCE SIGN SIGN LIST 10 workpiece gripping device 12 robots 14 Sensor 16 Robot control 28 robot hands 30 containers 32, 32a, 32b Workpiece 42, 44, 46 Path of movement QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2004-295 223 A

[0003] JP 2011-179 909 A

[0003] JP 2015-089 590 A

[0003]

Claims

[1] Workpiece gripping device comprising: a robot with a hand configured to pick up a workpiece in a container; a shape-setting unit configured to set the shapes of the hand, the container, and the workpiece; a sensor configured to detect the container and the workpiece in the container; a picking position / picking posture determining unit configured to determine a picking position and a picking posture of the hand when the hand picks up a detected workpiece; a picking position / picking posture detecting unit configured to determine an intermediate position at which the hand is positioned above and inside the container and at which the position of the hand is the picking position when the hand performs an operation to pick up the detected workpiece; and an operation control unit configured to move the hand from the intermediate position to the picking position only by a translational movement. [2] The workpiece gripping device according to claim 1, wherein the intermediate position determining unit is configured to approximate the shape of the hand to a basic shape including at least one of a sphere, a cylinder, a polygonal prism, and a polyhedron, and determines the intermediate position such that the entire basic shape is positioned above and within the container. [3] The workpiece pick-up device according to claim 1, wherein the intermediate position determining unit is configured to determine a convex hull enclosing the hand and determine the intermediate position such that each vertex of the convex hull is positioned above and within the container. [4] A workpiece picking-up device according to claim 1, wherein the operation control unit is configured to control the robot not to perform the operation of picking up the detected workpiece when the intermediate position cannot be set above and inside the container. [5] A workpiece pick-up device according to claim 1, wherein the intermediate position detecting unit is configured to determine the intermediate position such that the hand is moved away from the detected workpiece by a predetermined distance along a moving path, the moving path having a portion shifted upward. [6] A method of picking up workpieces using a robot having a hand configured to pick up a workpiece in a container, the method comprising the following steps: Determining the shapes of the hand, the container, and the workpiece; Detecting the container and the workpiece in the container; Determining a picking position and a picking posture of the hand when the hand picks up a detected workpiece; Determining an intermediate position in which the hand is located above and inside the container and in which the position of the hand represents the picking position when the hand performs an operation to pick up the detected workpiece; and Moving the hand from the intermediate position to the picking position only by a translational movement. [7] Control of a robot having a hand configured to pick up a workpiece in a container and having a sensor configured to detect the container and the workpiece in the container, the control comprising: a shape-setting unit configured to set the shapes of the hand, the container, and the workpiece; a picking position / picking posture determining unit configured to determine a picking position and a picking posture of the hand when the hand picks up a detected workpiece; a picking position / picking posture detecting unit configured to determine an intermediate position at which the hand is positioned above and inside the container and at which the position of the hand represents the picking position when the hand performs an operation to pick up the detected workpiece; and an operation control unit configured to move the hand from the intermediate position to the picking position only by a translational movement.

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