Workpiece taking-out device, workpiece taking-out method, and control device

Abstract

The invention provides a workpiece taking-out device, a taking-out method and a control device, which can effectively take out a workpiece in a container. The workpiece taking-out device includes: a robot on which a robot hand for taking out a workpiece in a container is mounted; a shape setting unit that sets the shapes of the manipulator, the container, and the workpiece; a sensor configured to detect the container and the workpiece in the container; a take-out position / posture determination unit that determines a take-out position and a take-out posture of the robot when the detected workpiece is taken out by the robot; a relay position determination unit that determines a relay position at which the manipulator is positioned above and inside the container and the posture of the manipulator is the take-out posture when the detected workpiece is taken out; and an operation control unit that moves the robot from the relay position to the take-out position only by translational movement.

Description

Technical Field

[0001] Embodiments of the present invention relate to a workpiece taking-out device, a workpiece taking-out method, and a control device. Background Art

[0002] Conventionally, there are well-known devices that recognize the position and posture of bulk objects and take out the recognized objects using a robot. As such devices, there are known devices that recognize the position of objects using pattern matching on a two-dimensional image of bulk objects obtained by photographing the bulk objects with a camera and a three-dimensional point set measured with a three-dimensional measuring machine (for example, see Patent Documents 1 and 2).

[0003] In addition, there is known an article taking-out device that can recognize the position and posture of bulk articles and take out the articles using various three-dimensional measuring machines without performing pattern matching (see, for example, Patent Document 3).

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2004-295223

[0007] Patent Document 2: Japanese Patent Application Publication No. 2011-179909

[0008] Patent Document 3: Japanese Patent Application Publication No. 2015-089590 Summary of the invention

[0009] Problems to be solved by the invention

[0010] The workpieces in bulk in the container are in various postures. When taking out the workpieces in various postures by the robot, the manipulator mounted on the robot needs to be tilted according to the posture of the workpiece. However, if the posture of the manipulator is changed according to the posture of the workpiece before taking out the workpiece, the manipulator may interfere with the workpieces located in the container or around the workpiece to be taken out during the posture change.

[0011] There are methods for detecting obstacles that may interfere with the robot using three-dimensional vision sensors, but the only information that can be obtained by the vision sensor is the surface information of the upper surface of the container, and the three-dimensional vision sensor sometimes fails to obtain three-dimensional data. Therefore, it is difficult to reliably predict and avoid interference using the vision sensor.

[0012] In addition, an automatic path generation technology has been proposed to obtain a movement trajectory of a robot in a manner that does not interfere with the surrounding environment. However, in order to realize this technology, a high-performance computing processor and a large amount of processing time are required.

[0013] Means for solving problems

[0014] One method disclosed herein is a workpiece removal device, comprising: a robot equipped with a manipulator for removing a workpiece from a container; a shape setting unit, which sets the shape of the manipulator, the container, and the workpiece; a sensor, which is configured to detect the container and the workpiece in the container; a removal position posture determination unit, which calculates the removal position and removal posture of the manipulator when the manipulator removes the detected workpiece; a relay position determination unit, which determines that the manipulator is located at a relay position above and inside the container and the posture of the manipulator is the removal posture when performing the action of removing the detected workpiece; and a motion control unit, which moves the manipulator from the relay position to the removal position only by translation.

[0015] Another embodiment of the present disclosure is a workpiece removal method, which uses a robot equipped with a manipulator for removing workpieces from a container, and the workpiece removal method includes the following processing: setting the shapes of the manipulator, the container, and the workpiece; detecting the container and the workpiece in the container; calculating the removal position and removal posture of the manipulator when the manipulator removes the detected workpiece; when removing the detected workpiece, determining that the manipulator is located above and inside the container and the posture of the manipulator is a relay position of the removal posture; and moving the manipulator from the relay position to the removal position only by translation.

[0016] Another embodiment of the present disclosure is a control device, which is a robot equipped with a manipulator for taking out a workpiece in a container, and a control device configured to detect the container and the workpiece, comprising: a shape setting unit, which sets the shape of the manipulator, the container, and the workpiece; a taking-out position posture determination unit, which calculates the taking-out position and taking-out posture of the manipulator when the manipulator takes out the detected workpiece; a relay position determination unit, which determines a relay position in which the manipulator is located above and inside the container and the posture of the manipulator is the taking-out posture when taking out the detected workpiece; and a motion control unit, which moves the manipulator from the relay position to the taking-out position only by translation.

[0017] Effects of the Invention

[0018] According to the present invention, the intermediate position is located above and inside the container, and the manipulator does not change its posture after the intermediate position, but only approaches the object to be taken out by translation. Therefore, the manipulator can perform efficient taking-out operation without interfering with the container or other workpieces. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1It is a schematic structural diagram of a workpiece removal device according to an embodiment.

[0020] Figure 2 This is a flowchart showing an example of the process at the time of setting.

[0021] Figure 3 This is a flowchart showing an example of processing when taking out is performed.

[0022] Figure 4 This is a schematic diagram showing an example of a movement path of the robot. DETAILED DESCRIPTION

[0023] Figure 1 The workpiece removal device 10 has: at least one robot 12; a three-dimensional visual sensor 14; and a control device 16, which is connected to the robot 12 and the sensor 14 by wire or wirelessly to control the robot 12 and the sensor 14.

[0024] The robot 12 is, for example, an industrial vertical multi-joint robot of a serial link structure, comprising: a base 18 installed in a specified place such as a production line in a factory; a rotating body 20 rotatably mounted on the base 18; a first arm (upper arm) 22 rotatably mounted relative to the rotating body 20; a second arm (forearm) 24 rotatably mounted relative to the first arm 22; a wrist (mechanical interface) 26 rotatably mounted on the second arm 24; and a robot manipulator 28 mounted on the wrist 26. The robot 12 is configured to take out workpieces 32 randomly stacked in a container 30 one by one.

[0025] In this embodiment, the three-dimensional sensor 14 is configured to detect the position of the container 30 and the workpiece 32 in the container 30 according to instructions from the control device 16. For example, it can use a stereo camera that detects the three-dimensional position based on the parallax captured by two two-dimensional cameras, a TOF (Time of Flight) camera that captures distance images using the light flight time method, etc.

[0026] The robot 12 is configured to be able to perform various operations such as taking out a workpiece according to a command sent from the control device 16. The control device 16 has a processor and a storage unit (memory, etc.), and can control the sensor 14 that detects the container 30 and the workpiece 32 in the container 30 in addition to controlling the robot 12. In the present embodiment, the processor of the robot control device 16 has the functions of a shape setting unit that sets the shapes of the robot 28, the container 30, and the workpiece 32; a taking-out position and posture determination unit that determines the taking-out position and taking-out posture of the robot 28 when the robot 28 takes out the detected workpiece 32; a relay position determination unit that determines the relay position (described later) in which the robot 28 is located above and inside the container 30 and the posture of the robot 28 is the taking-out posture when taking out the detected workpiece 32; and an action control unit that moves the robot 28 from the relay position to the taking-out position only by translation. However, the present disclosure is not limited to this. For example, a computer (not shown) such as a personal computer (PC) having a processor and a storage unit (memory, etc.) connected to the control device 16 in a wired or wireless manner may generate a robot's action program, etc., and the generated program, etc. may be sent from the computer to the control device 16.

[0027] Figure 2 This is a flowchart showing an example of processing performed as a setting before the workpiece removal device 10 actually removes the workpiece 32. First, in step S1, the shape and size of the container 30 in which the workpieces 32 are bulked are set. Next, in step S2, the shape, size, and positions of representative points such as the tool tip point (TCP) of the robot manipulator 28 are set.

[0028] Next, in step S3, the shape and size of the workpiece 32 are set. Finally, in step S4, the position and posture of the robot 28 relative to the workpiece 32 are set, that is, the position and posture of the robot 28 relative to the workpiece 32 when the robot 28 takes out the workpiece 32. In addition, the settings of steps S1-S4 can be performed by the user through an input unit such as an appropriate user interface (not shown), or can be automatically performed by the control device 14 or a processor of another computer based on a 3D model of the container, the robot, and the workpiece.

[0029] Figure 3 1 is a flowchart showing an example of processing when the workpiece removal device 10 removes the workpiece 32. First, in step S11, three-dimensional data of the container 30 and the workpiece 32 in the container 30 is obtained. Specifically, the sensor 14 is used to obtain image data or a three-dimensional point group of the container 30 and the workpiece 32.

[0030] Next, in step S12, the position of container 30 is detected. Specifically, the position of container 30 is determined by a method such as model matching using the three-dimensional data of container 30 acquired in step S11 and the shape and size of container 30 set in step S1.

[0031] Next, in step S13, the position of the workpiece 32 in the container 30 is detected. Specifically, as in step S12, the position of the workpiece 32 is determined by a method such as model matching using the three-dimensional data of the workpiece 32 obtained in step S11 and the shape and size of the workpiece 32 set in step S3. At this time, the posture of the workpiece 32 can also be determined.

[0032] Next, in step S14, the removal position and posture of the robot 28 relative to the workpiece 32 are obtained. Specifically, based on the position (or position and posture) of the workpiece 32 detected in step S13 and the removal position and posture of the robot set in the above-mentioned step S4, the removal position and removal posture of the robot 28 when removing the detected workpiece 32 are obtained.

[0033] Next, in step S15, the intermediate position that the robot 28 should pass through before reaching the removal position obtained in step S14 is determined. The intermediate position in this embodiment refers to a position that the robot 28 (representative point, etc.) must pass through before reaching the workpiece 32 to be removed. At this intermediate position, the robot 28 is located above and inside the container 30 in the state of assuming the above-mentioned removal posture. Here, "above the container" means Figure 1 The space above the upper end 38 of the container 30 in the vertical direction as shown in the figure, and the "inner side of the container" refers to the space above the upper end 38 of the container 30 in the vertical direction as shown in the figure. Figure 1 As shown by reference numeral 40 , the space is obtained by scanning the opening of the container 30 vertically upward.

[0034] As a specific method for calculating the relay position, for example, there is a method of using the CAD data of the robot 28 to determine whether the robot 28 interferes with the container 30 or the workpiece 32. However, generally speaking, a robot robot has a complex shape, and therefore, although the calculation using the CAD data is accurate, the operation processing may take time.

[0035] Therefore, for example, the shape of the robot 28 may be approximated to include at least one basic shape of a sphere, a cylinder, a polygonal prism, and a polyhedron that includes the shape, and the relay position may be obtained in such a manner that the entire basic shape is located above and inside the container 30. Alternatively, a convex hull (convex polyhedron) that includes the robot 28 may be obtained based on the CAD data of the robot 28, and the relay position may be obtained in such a manner that each vertex of the convex hull is located above and inside the container 30. In either case, the calculation time can be greatly shortened compared to using the CAD data directly.

[0036] In addition, in step S15, for the workpiece to be taken out, it is sometimes impossible to calculate or determine the relay position that satisfies the above condition (the relay position is located above and inside the container). In this case, since it can be determined that there is a problem with which workpiece should be taken out, it is preferred not to perform the work of taking out the workpiece to be taken out, but to start again from the work of taking out another workpiece as the object of taking out.

[0037] Next, in step S16, the robot 28 is moved to the intermediate position obtained in step S15. Here, the robot 12 is controlled so as to be in the removal posture obtained in step S14 before the robot 28 reaches the intermediate position. Figure 1 As shown, when the approach direction of the robot 28 relative to the object workpiece 32 is the z direction of the coordinate system 34 set for the workpiece 32, the robot 28 presents a picking posture at the relay position in which the z direction of the coordinate system 36 set for the robot 28 is parallel to the z direction of the coordinate system 34.

[0038] Next, in step S17, the robot 28 is translated (moved in parallel) from the intermediate position to the workpiece removal position. Figure 1 As shown in FIG. 1 , the robot 28 moves along the moving path 42 without changing its posture from the relay position to the object workpiece 32 to be removed. In addition, the moving path from the relay position to the object workpiece 32 to be removed may be a simple straight line or may be a straight line. Figure 1 Such a structure may include straight lines in different directions connected by at least one bending point, and may also include curved lines at least partially.

[0039] Finally, in step S18, the workpiece 32 to be taken out is taken out by gripping, suction, etc. of the robot 28. When another workpiece is taken out, the above-mentioned steps S11 to S18 are repeated.

[0040] Figure 4This is a schematic diagram for explaining an example of processing for obtaining the intermediate position. Assuming that a workpiece 32a is detected as a pick-up target, if the intermediate position is determined so that the robot 28 moves along a straight line (movement path) 44 from the intermediate position to the workpiece 32a, there is a possibility that another workpiece 32b will interfere with the robot 28. On the other hand, in order to pick up the workpiece 32a, the robot 28 needs to move along the straight line 44 at least in the vicinity of the workpiece 32a.

[0041] Therefore, as shown by reference symbol 46, by determining the relay position in a manner that causes the robot 28 to move along a moving path that shifts a portion of the moving path away from the removal target workpiece 32a by a fixed distance upward, interference with other workpieces 32b can be reliably avoided and the removal target workpiece 32a can be removed.

[0042] According to the above embodiment, the intermediate position is located above and inside the container 30, and the robot 28 does not change its posture after the intermediate position, but only moves to approach the object to be taken out by translation. Therefore, the robot 28 can perform a smooth taking-out operation without interfering with the container 30 or other workpieces 32.

[0043] Description of Reference Numerals

[0044] 10 Workpiece removal device

[0045] 12 Robot

[0046] 14 Sensors

[0047] 16 Control Devices

[0048] 28 Robot Manipulator

[0049] 30 Containers

[0050] 32, 32a, 32b Workpiece

[0051] 42, 44, 46 Movement paths.

Claims

1. A workpiece removal device, characterized in that: The workpiece removal device comprises: A robot equipped with a manipulator for taking out workpieces from a container; A shape setting unit, which sets the shapes of the robot, the container, and the workpiece; a sensor configured to detect the container and a workpiece within the container; a picking-up position and posture determining unit for determining a picking-up position and a picking-up posture of the robot when the robot picks up the detected workpiece; a relay position determination unit that determines a relay position in which the robot is located above and inside the container and the posture of the robot is the taking-out posture when taking out the detected workpiece; and The motion control unit moves the robot from the relay position to the removal position only by translation.

2. The workpiece removal device according to claim 1, characterized in that: The relay position determination unit approximates the shape of the robot to a basic shape including at least one of a sphere, a cylinder, a polygonal prism, and a polyhedron, and determines the relay position so that the entire basic shape is located above and inside the container.

3. The workpiece removal device according to claim 1, characterized in that: The relay position determination unit obtains a convex hull that includes the robot hand, and determines the relay position so that each vertex of the convex hull is located above and inside the container.

4. The workpiece removal device according to claim 1, characterized in that: When the intermediate position cannot be set above and inside the container, the operation control unit controls the robot so as not to perform the removal operation of the detected workpiece.

5. The workpiece removal device according to claim 1, characterized in that: The intermediate position determination unit determines the intermediate position so that the robot moves along a movement path obtained by shifting a portion of the movement path away from the detected workpiece by a fixed distance upward.

6. A method for removing a workpiece, using a robot equipped with a manipulator for removing a workpiece from a container, characterized in that: The workpiece removal method includes the following processing: Setting the shapes of the manipulator, the container, and the workpiece; detecting the container and the workpiece in the container; Calculating a taking-out position and a taking-out posture of the robot when the robot takes out the detected workpiece; When taking out the detected workpiece, determining that the robot is located above and inside the container and the posture of the robot is a relay position of the taking-out posture; and The robot arm is moved from the relay position to the removal position only by translational movement.

7. A control device comprising a robot equipped with a manipulator for taking out a workpiece in a container, and a sensor configured to detect the container and the workpiece, characterized in that: The control device has: A shape setting unit, which sets the shapes of the robot, the container, and the workpiece; a picking-up position and posture determining unit for determining a picking-up position and a picking-up posture of the robot when the robot picks up the detected workpiece; a relay position determination unit that determines a relay position in which the robot is located above and inside the container and the posture of the robot is the taking-out posture when taking out the detected workpiece; and The motion control unit moves the robot from the relay position to the removal position only by translation.

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