Workpiece removal device

Abstract

The present invention provides a workpiece taking-out device that can stabilize the cycle time even though it involves an operation of reversing the workpiece. The workpiece taking-out system includes: a workpiece taking-out device for taking out a workpiece; and a control device for setting the taking-out order of the workpiece. The control device includes: a storage unit that stores the setting posture, which is the posture when the workpiece is set on the jig; a current posture detection unit that detects the current posture of the workpiece; a change amount calculation unit that calculates the change amount between the setting posture and the current posture; a taking-out candidate determination unit that compares the change amount with a threshold value and determines the workpiece to be the priority taking-out candidate based on the result of the comparison; and a taking-out instruction unit that outputs a first instruction to the workpiece taking-out device to make it take out the priority taking-out candidate workpiece.

Description

Technical Field

[0001] The present invention relates to a workpiece taking-out device. Background Art

[0002] Sometimes, it is necessary to take out a workpiece from a state where workpieces are scattered and stacked and set it on a prescribed jig. At this time, in order to efficiently calculate the position and posture of the workpiece using three-dimensional matching, there is known a technique of excluding a part of the measurement data used in the three-dimensional matching based on the position and posture of the workpiece calculated by a position and posture calculation device (for example, refer to Patent Document 1).

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2017-102529 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] In the case where the workpiece has front and back sides, sometimes a reverser that is separately provided from the jig and reverses the front and back sides of the workpiece is used to reverse the front and back sides of the workpiece and then set the workpiece on the jig. When the workpiece is reversed, compared with the case of directly setting the workpiece on the jig, it takes time corresponding to the amount of work for reversing the workpiece. Therefore, when reverse operations are continuously performed, there is a case where the cycle time during the reverse operation becomes long and hinders subsequent processes.

[0008] There is a need for a technique related to a workpiece taking-out device that can stabilize the cycle time when taking out a workpiece although it involves an operation of reversing the workpiece.

[0009] Solution to the Problem

[0010] One aspect of the present disclosure includes: a workpiece taking-out device for taking out a workpiece; and a control device for setting the taking-out order of the workpiece, wherein the control device includes: a storage unit that stores the posture when the workpiece is set on the jig, i.e., the setting posture; a current posture detection unit that detects the current posture of the workpiece, i.e., the current posture; a change amount calculation unit that calculates the change amount between the setting posture and the current posture; a comparison unit that compares the change amount with a threshold value; a taking-out candidate determination unit that determines the workpiece with the change amount less than the threshold value as a priority taking-out candidate; and a taking-out instruction unit that outputs a first instruction to the workpiece taking-out device to make it take out the workpiece that is the priority taking-out candidate.

[0011] Effects of the Invention

[0012] According to one aspect, although there is an operation of reversing the workpiece, the cycle time for taking out the workpiece can be stabilized. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 FIG. is a diagram showing the overall structure of a workpiece take-out system according to one embodiment.

[0014] Figure 2 FIG. is a functional block diagram of a workpiece take-out device according to one embodiment.

[0015] Figure 3 FIG. is a diagram showing the set posture of a workpiece according to one embodiment.

[0016] Figure 4 FIG. is a diagram showing a method for detecting the current posture of a workpiece according to one embodiment.

[0017] Figure 5 FIG. is a diagram showing a method for detecting the current posture of a workpiece according to one embodiment.

[0018] Figure 6A FIG. is a diagram showing an outline of a method for calculating the amount of change between the set posture and the current posture in one embodiment.

[0019] Figure 6B FIG. is a diagram showing an outline of a method for calculating the amount of change between the set posture and the current posture in one embodiment.

[0020] Figure 7 FIG. is a diagram showing a method for determining a preferred take-out candidate according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, embodiments of the present invention will be described by referring to Figures 1 to 7 to.

[0022] 〔1 Overall Structure〕

[0023] Figure 1 FIG. shows the overall structure of the workpiece take-out system 1 according to the present embodiment. The workpiece take-out system 1 includes a control device 10 and a workpiece take-out device 20. The control device 10 and the workpiece take-out device 20 are set as a one-to-one corresponding group and are connected in a communicable manner. Regarding the connection between the control device 10 and the workpiece take-out device 20, they may be directly connected via a connection interface, or may be connected via a network such as a LAN.

[0024] The control device 10 is a device that controls the workpiece take-out device 20 to perform a specified operation. In particular, in the present embodiment, the control device 10 can set the take-out order in which the workpiece take-out device 20 takes out the workpiece.

[0025] The workpiece taking-out device 20 is a device that takes out workpieces one by one from a plurality of workpieces piled up haphazardly. The workpiece taking-out device 20 can be, for example, a robot. In this case, the robot is, for example, a 6-axis multi-joint robot and has a hand that can hold a workpiece machined by a machine tool or a workpiece to be machined thereafter.

[0026] The workpiece taking-out device 20 takes out and transports, for example, workpieces according to the motion instructions generated by the motion program set in the control device 10.

[0027] 〔Structure of the control device〕

[0028] Figure 2 is a functional block diagram of the control device 10. As Figure 2 shown, the control device 10 includes a storage unit 100 and a control unit 110.

[0029] The storage unit 100 stores the setting posture, that is, the posture when the workpiece is set on the jig.

[0030] When the storage unit 100 stores the setting posture, prior to this, the operator of the control device 10 first performs a teaching operation on the control device 10.

[0031] More specifically, first, the operator teaches the physical shape model of the workpiece to the control device 10 using the 3D CAD data of the workpiece. Second, the operator teaches the control device 10 the setting posture in which the workpiece is set on the jig.

[0032] Figure 3 shows an example of the setting posture in which the workpiece 30 is set on the jig 50 taught to the control device 10.

[0033] In Figure 3 the example shown, the workpiece 30 is composed of a first rectangular parallelepiped 30A and a second rectangular parallelepiped 30B. The lengths of the first rectangular parallelepiped 30A and the second rectangular parallelepiped 30B in the width direction are the same, and the axes of the two perpendicular to the width direction are 90° to each other.

[0034] In addition, the jig 50 includes a first rectangular parallelepiped 50A, a second rectangular parallelepiped 50B, and a third rectangular parallelepiped 50C. The first rectangular parallelepiped 50A is connected to the second rectangular parallelepiped 50B and the third rectangular parallelepiped 50C. The first rectangular parallelepiped 50A supports the first rectangular parallelepiped 30A of the workpiece 30 from below the first rectangular parallelepiped 30A of the workpiece 30. On the other hand, the second rectangular parallelepiped 50B and the third rectangular parallelepiped 50C press the first rectangular parallelepiped 20A of the workpiece 30 from above the first rectangular parallelepiped 20A of the workpiece 30. In addition, the rectangular parallelepiped 30B is arranged between the second rectangular parallelepiped 50B and the third rectangular parallelepiped 50C of the jig 50 in a state separated from the second rectangular parallelepiped 30B of the workpiece 30.

[0035] Further, in the workpiece coordinate system of the workpiece 30, the axis in the long side direction of the first rectangular parallelepiped 30A is defined as the X-axis, and the axis in the normal direction of the first rectangular parallelepiped 30A, which is included in the second rectangular parallelepiped 30B of the workpiece 30, is defined as the Z-axis. Additionally, the axis orthogonal to both the X-axis and the Z-axis is defined as the Y-axis.

[0036] As an example, the operator of the control device 10 teaches the control device 10 Figure 3 the physical shape model of the workpiece 30 and the setting posture set on the jig 50 as shown. Thereby, the storage unit 100 can store the posture when the workpiece 30 is set on the jig 50, that is, the setting posture.

[0037] The control unit 110 includes a CPU, a ROM, a RAM, a CMOS memory, etc., which are configured to be able to communicate with each other via a bus to form the control unit 110, and the structure is well-known to those skilled in the art.

[0038] The CPU is a processor for controlling the entire control device 10. The CPU is configured to: read the system program and application program stored in the ROM via the bus and control the entire control device 10 according to the system program and application program. Thus, as Figure 2 shown, the control unit 110 implements the functions of the current posture detection unit 111, the change amount calculation unit 112, the take-out candidate determination unit 113, the take-out instruction unit 114, the reverse instruction unit 115, and the timing setting unit 116.

[0039] The current posture detection unit 111 detects the current posture of the workpiece 30, that is, the current posture.

[0040] Figure 4 and Figure 5 are diagrams showing examples of the detection method for the current posture detected by the current posture detection unit 111. As Figure 4 shown, a 3D sensor 70 is provided above the workpiece take-out device 20, which is a robot, and the tray 35 that stores a plurality of workpieces 30 piled up in a scattered manner. The current posture detection unit 111 uses the image sensed by the 3D sensor 70 to detect the current position and posture of the workpiece 30.

[0041] In particular, as Figure 5 shown, the current posture detection unit 111 detects the above-mentioned X-axis and Z-axis for each workpiece 30. These detected X-axis and Z-axis are used in the change amount calculation unit 112 described later.

[0042] The change amount calculation unit 112 calculates the change amount between the setting posture and the current posture.

[0043] Figure 6A and Figure 6BIt is a diagram showing an outline of a calculation method for the amount of change between a set pose and the current pose. As Figure 6A and Figure 6B shown, the above-mentioned X-axis, Y-axis, and Z-axis are set for the workpiece 30. In particular, Figure 6A shows the X-axis, Y-axis, and Z-axis when the workpiece 30 is in the set pose. Additionally, Figure 6B shows the X-axis, Y-axis, and Z-axis (Z' axis) when the workpiece 30 is in the current pose.

[0044] In Figure 6A , the pose vector in the Z direction when the workpiece 30 is in the set pose is set as REF_Z. Additionally, in Figure 6B , the pose vector in the Z direction when the workpiece 30 is in the current pose is set as FOUND_Z.

[0045] The change amount calculation unit 112 calculates the inner product of REF_Z and FOUND_Z, i.e., REF_Z·FOUND_Z, as the change amount between the set pose and the current pose.

[0046] The extraction candidate determination unit 113 compares the change amount calculated by the change amount calculation unit 112 with a threshold value, and determines the workpiece 30 as the preferred extraction candidate based on the result of this comparison.

[0047] When the detected current pose is close to the pose placed on the jig 50, the value of the change amount calculated by the change amount calculation unit 112, i.e., the inner product REF_Z·FOUND_Z, is close to 1. When the poses differ by nearly 90°, the value of this inner product REF_Z·FOUND_Z is close to 0. Additionally, when the Z-axis direction is reversed, the value of the inner product REF_Z·FOUND_Z becomes negative.

[0048] Therefore, when the value of the inner product REF_Z·FOUND_Z related to a certain workpiece 30 is less than 0, or when the value of this inner product REF_Z·FOUND_Z is less than a specified threshold value, the extraction candidate determination unit 113 sets that the workpiece 30 needs to perform a reverse action and reduces the extraction priority of this workpiece 30. Conversely, the other workpieces 30 are determined as the preferred extraction candidates.

[0049] Figure 7 Shows this specific example. As Figure 7 shown, the extraction candidate determination unit 113 marks the workpieces 30 whose inner product REF_Z·FOUND_Z value is less than 0 or is above a specified threshold value in the image sensed by the 3D sensor 70 (represented by an ellipse in Figure 7 ), and determines the other workpieces 30 as the preferred extraction candidates.

[0050] The extraction instruction unit 114 outputs a first instruction to the workpiece extraction device 20 for extracting the workpiece 30 of the priority extraction candidate determined by the extraction candidate determination unit 113. Thereby, the workpiece extraction device 20 preferentially extracts the workpiece 30 determined by the extraction candidate determination unit 113.

[0051] When the rotation angle of the workpiece 30 in the current posture with respect to the workpiece 30 in the set posture, calculated based on the value of the inner product REF_Z·FOUND_Z, is equal to or greater than a specified value, the reverse instruction unit 115 outputs a second instruction for reversing the workpiece 30 after extracting the workpiece 30. Thereby, the workpiece extraction device 20 reverses the workpiece 30 not determined by the extraction candidate determination unit 113 and then extracts it.

[0052] The timing setting unit 116 sets the output timing of the second instruction output by the reverse instruction unit 115 to a specified timing. Thereby, it is no longer necessary to continuously perform the extraction of the workpiece 30 that needs to be reversed, and the cycle time can be stabilized.

[0053] Here, the "specified timing" refers to a timing with a certain degree or more of time remaining before the next process. The "specified timing" can also be, for example, a timing that does not affect the cycle of the next process. More specifically, it can be a buffer is provided for storing the workpiece in a posture that can already be set on the jig in advance, and the "specified timing" is such that the workpiece is completely stored in this buffer, etc. In addition, the "specified timing" can also be a timing at which the workpiece taken out without being reversed cannot be recognized.

[0054] 〔3 Operations of the Embodiment〕

[0055] In the workpiece extraction system 1 according to the present embodiment, the control device 10 calculates the change amount between the set posture, which is the posture when the workpiece 30 is set on the jig 50, and the current posture, which is the current posture of the workpiece 30, and determines the workpiece 30 as the priority extraction candidate based on the comparison result between the change amount and the threshold value. On this basis, the workpiece extraction device 20 preferentially extracts the workpiece 30 determined as the priority extraction candidate, and extracts the other workpieces 30 at a specified timing.

[0056] 〔4 Effects Achieved by the Embodiment〕

[0057] (1) The workpiece taking-out system involved in the above-described embodiment (for example, the above-mentioned "workpiece taking-out system 1") includes: a workpiece taking-out device (for example, the above-mentioned "workpiece taking-out device 20") for taking out a workpiece (for example, the above-mentioned "workpiece 30"); and a control device (for example, the above-mentioned "control device 10") for setting the taking-out order of the workpiece. The control device includes: a storage unit (for example, the above-mentioned "storage unit 100") for storing the posture when the workpiece is set on the jig, that is, the setting posture; a current posture detection unit (for example, the above-mentioned "current posture detection unit 111") for detecting the current posture of the workpiece, that is, the current posture; a change amount calculation unit (for example, the above-mentioned "change amount calculation unit 112") for calculating the change amount between the setting posture and the current posture; a taking-out candidate determination unit (for example, the above-mentioned "taking-out candidate determination unit 113") for comparing the change amount with a threshold value and determining the workpiece as the priority taking-out candidate based on the result of the comparison; and a taking-out instruction unit (for example, the above-mentioned "taking-out instruction unit 114") for outputting a first instruction to the workpiece taking-out device to make it take out the workpiece of the priority taking-out candidate.

[0058] Thus, although there is an operation of reversing the workpiece, the cycle time can be stabilized.

[0059] (2) In the workpiece taking-out system described in (1), the change amount calculation unit calculates the inner product of the vectors in an arbitrary axial direction in the workpiece coordinate system of the workpiece in the setting posture and the vectors in the arbitrary axial direction in the current posture as the change amount between the setting posture and the current posture.

[0060] Thus, the process of stabilizing the cycle time can be performed by simple calculation.

[0061] (3) In the workpiece taking-out system described in (2), the control device further includes: a reverse instruction unit (for example, the above-mentioned "reverse instruction unit 115"). When the rotation angle of the workpiece in the current posture relative to the workpiece in the setting posture calculated based on the inner product is equal to or greater than a specified value, the reverse instruction unit outputs a second instruction for reversing the workpiece after taking out the workpiece; and a timing setting unit (for example, the above-mentioned "timing setting unit 116") for setting the timing of the output of the second instruction to a specified timing.

[0062] Thus, continuous reverse operations of the workpiece 30 are suppressed, and the cycle time when taking out the workpiece becomes stable.

[0063] Description of Reference Numerals

[0064] 1: Workpiece removal system; 10: Control device; 20: Workpiece removal device; 30: Workpiece; 50: Fixture; 100: Storage unit; 110: Control unit; 111: Current posture detection unit; 112: Variation calculation unit; 113: Removal candidate determination unit; 114: Removal instruction unit; 115: Reverse instruction unit; 116: Timing setting unit.

Claims

1. A workpiece taking-out system, comprising: A workpiece taking-out device for taking out a workpiece from a plurality of workpieces, the workpiece taking-out device transporting the taken-out workpiece and setting it on a jig; and A control device for setting the taking-out order of the plurality of workpieces, Among them, The control device includes: A storage unit that stores in advance, by a teaching operation, the posture when the taken-out workpiece is set on the jig, i.e., the setting posture; A current posture detection unit that detects the current posture of each workpiece among the plurality of workpieces, i.e., the current posture; A variation amount calculation unit that calculates the variation amount between the setting posture and the current posture; A taking-out candidate determination unit that compares the variation amount with a threshold value and determines, based on the result of the comparison, the workpiece to be the preferred taking-out candidate; And A taking-out instruction unit that outputs a first instruction to the workpiece taking-out device to cause it to take out the workpiece that is the preferred taking-out candidate.

2. The workpiece taking-out system according to claim 1, wherein The variation amount calculation unit calculates the inner product of the vectors in an arbitrary axial direction in the workpiece coordinate system of the workpiece in the setting posture and the vectors in the arbitrary axial direction in the current posture as the variation amount between the setting posture and the current posture.

3. The workpiece taking-out system according to claim 2, wherein The control device further includes: A reverse instruction unit that, when the rotation angle of the workpiece in the current posture relative to the workpiece in the setting posture calculated based on the inner product is equal to or greater than a specified value, outputs a second instruction for causing the workpiece to reverse after taking out the workpiece; And A timing setting unit that sets the timing of outputting the second instruction to a specified timing.

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