Pickup Device

Abstract

To provide a pickup device that can reduce damage of a cable caused by motion of a robot, without designing the robot newly.SOLUTION: The pickup device comprises: a robot having a robot hand part; a cable connected to the robot from the outside of the robot; a first fixed part fixed to the cable, outside the robot; a second fixed part fixed to the cable, at a position farther away from the robot hand part than the first fixed part; and a tension applying mechanism that applies tension to a first cable portion through the first fixed part, where a second cable portion is maintained in a loosened state.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a pickup device. [Background technology]

[0002] Due to labor shortages in factories, etc., there is a growing demand for robotic pickup devices that pick up parts. In addition, in recent years, the movements required of robots have become more extensive and complex in order to realize automated assembly of a wide variety of parts.

[0003] The robot used in the pickup device has a robot hand for picking and placing parts. The robot is also connected to a cable for driving the motor for the robot hand, for example. The cable must be laid out so that it is not damaged by the robot's operation or its presence does not adversely affect the robot's operation. Patent Document 1 describes a technology related to an articulated welding robot with a cable running inside the robot arm. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-122405 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, with the technology described in Patent Document 1, it is necessary to design a new robot in order to change the structure of the robot arm in accordance with the cable layout, which increases costs.

[0006] An object of the present invention is to provide a pickup device that can reduce damage to cables caused by the operation of a robot without requiring a new robot design. [Means for solving the problem]

[0007] The pickup device of the present invention comprises a robot having a robot hand unit, a cable connected to the robot from outside the robot, a first fixed unit fixed to the cable outside the robot, a second fixed unit fixed to the cable at a position farther from the robot hand unit than the first fixed unit, and a tension applying mechanism that applies tension to the first cable portion between the robot hand unit and the first fixed unit via the first fixed unit, and the second cable portion between the first fixed unit and the second fixed unit is maintained in a slack state. [Effects of the Invention]

[0008] According to the present invention, damage to cables caused by the operation of a robot can be reduced without having to design a new robot. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic side view showing the configuration of a pickup device according to a first embodiment of the present invention. [Figure 2] 1 is a schematic front view showing the configuration of a pickup device according to a first embodiment of the present invention. [Figure 3] FIG. 2 is a perspective view showing a configuration example of a robot hand unit. [Figure 4] FIG. 2 is a diagram illustrating an example of a cable configuration. [Figure 5] FIG. 2 is an enlarged view of a first fixing portion. [Figure 6] 10A and 10B are diagrams illustrating an example of the configuration of a first cable cover fixture. [Figure 7] FIG. 10 is an enlarged view of the second fixing portion. [Figure 8] FIG. 2 is a block diagram showing the configuration of a robot control system in the pickup device. [Figure 9] 10 is a flowchart showing a procedure for a robot control process. [Figure 10]FIG. 6 is a schematic diagram showing the configuration of a pickup device according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In this specification and the drawings, components having substantially the same functions or configurations are designated by the same reference numerals, and redundant description will be omitted.

[0011] First Embodiment FIG. 1 is a schematic side view showing the configuration of a pickup device according to a first embodiment of the present invention, and FIG. 2 is a schematic front view showing the configuration of a pickup device according to the first embodiment of the present invention. As shown in FIGS. 1 and 2, the pickup device 10 includes a robot 12, a cable 14, a first fixed portion 16, a second fixed portion 18, and a tension applying mechanism 20.

[0012] The robot 12 is a multi-axis robot. In this embodiment, as an example, the robot 12 is a six-axis robot. The robot 12 is a so-called robot arm having a waist 21, a lower arm 22, an upper arm 24, and a wrist 26. A robot hand 28 is attached to the wrist 26 located at the tip of the robot arm. The robot hand 28 is disposed facing downward. The robot hand 28 has the function of picking and placing components (not shown). The robot hand 28 moves within a robot operating range 15 defined in a three-dimensional space (XYZ space). The robot operating range 15 is a range within which the robot hand 28 moves to pick and place components. The robot operating range 15 is determined by the working conditions of the robot 12, such as the size and shape of the components, the position to pick the components, and the position to place the components. In addition, the range of motion of the wrist 26 is set to ±180 degrees, and the movement path of the robot hand 28 is determined so as to be within the above range of motion by performing joint coordinate transformation from the Cartesian coordinates from the motion start position to the motion completion position using an inverse kinematic equation.

[0013] FIG. 3 is a perspective view showing an example of the configuration of the robot hand unit. 3, the robot hand unit 28 has a pair of grippers 30, a camera 32, a lighting device 34, a robot hand motor, and various sensors (not shown). The various sensors include, for example, a displacement sensor, a gripping force sensor, and a proximity sensor.

[0014] The pair of grippers 30 function as two fingers in the robot hand unit 28. The pair of grippers 30 are movable toward or away from each other, i.e., capable of opening and closing. The pair of grippers 30 open and close in accordance with the drive of a robot hand motor. The pair of grippers 30 have the function of gripping a component in order to pick it up and releasing the grip of the component in order to place it. The camera 32 is a camera for recognizing objects. Objects recognized by the camera 32 include components to be picked and placed. The lighting device 34 is a device that irradiates light onto the area photographed by the camera 32. The lighting device 34 is, for example, an LED lighting device that uses an LED (light emitting diode) as a light source.

[0015] In the following description, the mounting surface 12a of the robot 12 is defined as a horizontal reference plane, and two orthogonal axial directions parallel to this horizontal reference plane are defined as the X direction and the Y direction. The direction perpendicular to the X direction and the Y direction is defined as the Z direction. The X direction and the Y direction are both parallel to the horizontal direction, and the Z direction is parallel to the vertical direction.

[0016] 1 and 2, the cable 14 is connected to the robot 12 from the outside of the robot 12. By connecting the cable 14 to the robot 12 in this way, it is not necessary to design a new robot in order to run the cable inside the robot arm. Therefore, existing robots, including general-purpose robots, can be used as the robot 12.

[0017] The cable 14 is connected to the robot 12 from the side opposite to the orientation of the robot hand unit 28. In this embodiment, since the robot hand unit 28 is disposed facing downward, the cable 14 is connected to the robot 12 from the side opposite to the orientation of the robot hand unit 28, i.e., from above. Furthermore, one end 14a of the cable 14 is connected to the robot hand unit 28 from above the robot 12. By connecting the cable 14 to the robot 12 in this manner, the cable 14 is less likely to interfere with the upper arm 24 or robot hand unit 28 of the robot 12 while the robot 12 is operating.

[0018] The robot hand unit 28 may be positioned facing upward instead of downward. In this case, the cable 14 is connected to the robot 12 from below.

[0019] As shown in FIG. 4 , the cable 14 includes three cable wires 36 and a cable cover 38 that encases the cable wires 36. One end of the cable wires 36 is electrically connected to electronic devices mounted on the robot hand unit 28, such as a robot hand motor, a camera 32, and a lighting device 34. The other end of the cable wires 36 is electrically connected to a power supply, a drive board, an image processing board, and other devices (not shown). The number of cable wires 36 is determined depending on the number of electronic devices mounted on the robot hand unit 28. Therefore, the number of cable wires 36 is not limited to three, and may be two or less, or four or more. The cable cover 38 functions to bundle the multiple cable wires 36 and to protect the cable wires 36. The cable cover 38 is made of a resin such as polyamide, nylon 6, or polypropylene. The cable cover 38 is preferably made of a corrugated tube with appropriate flexibility.

[0020] One method for determining the size of the cable cover 38 is to calculate the cable space factor based on the inner diameter of the cable cover 38 and the sum of the cross-sectional areas of the cables 36, and then determine the size so that the cable space factor is equal to or less than a reference value. To prevent connectors from entering the interior of the cable cover 38, it is preferable to fix each cable 36 to the cable cover 38 at both ends of the cable cover 38. It is desirable for each cable 36 to have high flexibility. It is also preferable to determine the fixing position of the cable cover 38 taking into account the bending radius of the cable 36. The cable covers 38 do not all need to be one piece. For example, it is possible to configure the robot hand unit 28 to the second fixing unit 18 with a single cable cover 38, and to configure the portion beyond the second fixing unit 18 with a different cable cover. Furthermore, configuring the portion beyond the second fixing unit 18 with a half-split cable cover makes it easier to replace the cables 36, etc.

[0021] The cable 14 does not necessarily have to be provided with the cable cover 38. In that case, the cable 14 will be in a so-called bundled state, in which a predetermined number of cable wires 36 are bundled together.

[0022] 1 and 2 , the first fixed portion 16 is fixed to the cable 14 outside the robot 12, and the second fixed portion 18 is also fixed to the cable 14 outside the robot 12. Both the first fixed portion 16 and the second fixed portion 18 are located outside the robot motion range 15. Both the first fixed portion 16 and the second fixed portion 18 are fixed to a cable cover 38. The cable length from the robot hand portion 28 to the first fixed portion 16 is shorter than the cable length from the robot hand portion 28 to the second fixed portion 18. In other words, the second fixed portion 18 is fixed to the cable 14 at a position farther from the robot hand portion 28 than the first fixed portion 16. In this specification, the portion of the cable 14 between the robot hand portion 28 and the first fixed portion 16 is defined as a first cable portion 41, and the portion of the cable 14 between the first fixed portion 16 and the second fixed portion 18 is defined as a second cable portion 42.

[0023] The tensioning mechanism 20 is a mechanism that applies tension to the first cable portion 41 via the first fixing portion 16. The tensioning mechanism 20 is disposed outside the robot motion range 15. The first cable portion 41 is maintained in a tensioned state by the tensioning mechanism 20 during operation of the robot 12. In contrast, the second cable portion 42 is maintained in a slack state during operation of the robot 12. The amount of slack in the second cable portion 42 is set so that the second cable portion 42 is disposed outside the robot motion range 15 even when the second cable portion 42 is in its slackest state during operation of the robot 12. In other words, the second cable portion 42 is always disposed outside the robot motion range 15 in a slack state during operation of the robot 12.

[0024] The cable length from the robot hand unit 28 to the first fixed unit 16, i.e., the length of the first cable portion 41, is set to satisfy the condition that tension can be applied to the first cable portion 41 by the tensioning mechanism 20 regardless of whether the robot hand unit 28 is located at the farthest position or the closest position to the main body 20a of the tensioning mechanism 20 within the robot operating range 15. In other words, the first cable portion 41 is always maintained in a tensioned state during operation of the robot 12.

[0025] The tension applying mechanism 20 is configured, for example, by a spring balancer. A spring balancer is a device that applies tension by utilizing the tension of a spring. The tension applying mechanism 20 includes a main body 20a that houses a rotating drum and a spring (not shown), and an extendable wire 20b. The wire 20b is wound around the rotating drum inside the main body 20a. The spring applies torque to the rotating drum to wind up the wire 20b. However, the tension applying mechanism 20 is not limited to a spring balancer.

[0026] The tension applying mechanism 20 is attached to a safety fence 45. The safety fence 45 is installed at a suitable distance from the robot motion range 15 to prevent workers from coming into contact with the robot 12 while the robot 12 is in operation. The safety fence 45 is configured by appropriately combining a vertical frame 45a installed vertically and a horizontal frame 45b installed horizontally. A hook (not shown) is attached to the upper part of the main body 20a of the tension applying mechanism 20, and the main body 20a of the tension applying mechanism 20 is suspended from the horizontal frame 45b using this hook. Here, the position of the tension applying mechanism 20 (main body 20a) in the horizontal direction is near the center position of the robot motion range 15. In other words, the main body 20a of the tension applying mechanism 20 is located near the center position of the robot motion range 15. This makes it possible to minimize variations (fluctuations) in the tension applied by the tension applying mechanism 20 to the first cable portion 41.

[0027] Meanwhile, the tip of the wire 20b pulled out from the main body 20a of the tensioning mechanism 20 is connected to the first fixed portion 16. The wire 20b applies tension to the first cable portion 41 in a direction that pulls the first fixed portion 16 toward the main body 20a. The strength of the tension applied by the tensioning mechanism 20 to the first cable portion 41 is set appropriately depending on the weight and bendability of the cable 14, within a range that does not impose an excessive load on the cable 14. Based on the operating principle of a spring balancer, the tensioning mechanism 20 applies a substantially constant tension to the first cable portion 41 regardless of the amount of expansion or contraction of the wire 20b. Therefore, while the robot 12 is operating, the direction and amount of expansion of the wire 20b change depending on the displacement of the robot hand 28, but the tension applied to the first cable portion 41 by the tensioning mechanism 20 is maintained substantially constant.

[0028] FIG. 5 is an enlarged view of the first fixing part. As shown in FIG. 5, the first fixing portion 16 is configured by a first cable cover fixing device 51. As shown in FIG. 6, the first cable cover fixing device 51 has a gripping member 51a and a pressing member 51b. The gripping member 51a is a member that grips the cable cover 38. The pressing member 51b is a member that presses the cable cover 38. The pressing member 51b is configured to be detachable from the gripping member 51a. When fixing the first cable cover fixing device 51 to the cable cover 38, first, the cable cover 38 is fitted into the gripping member 51a, and then the pressing member 51b is attached to the gripping member 51a. In this way, the first cable cover fixing device 51 is fixed to the cable cover 38.

[0029] On the other hand, the first fixing portion 16 and the tension applying mechanism 20 are connected by a joint portion 55, as shown in Fig. 5. The joint portion 55 has a pair of joint members 55a, 55b, a connecting shaft portion 55c that rotatably connects the pair of joint members 55a, 55b, a connecting stud 55d detachably attached to one joint member 55a, and a connecting stud 55e detachably attached to the other joint member 55b. In contrast, the first cable cover fixing device 51 has a bracket 51c. The bracket 51c is fixed to the gripping member 51a by screws or the like. The bracket 51c also has a connecting hole 51d.

[0030] When connecting the first fixed part 16 and the tensioning mechanism 20 with the joint part 55, the connecting stud 55d removed from the joint member 55a is inserted into the hole 51d of the bracket 51c and attached to the joint member 55a. This connects the joint member 55a to the first cable cover fastener 51. Meanwhile, for the tensioning mechanism 20, the tip of the wire 20b is attached to the connecting stud 55e. A hook or carabiner (not shown) is attached to the tip of the wire 20b, and this hook or carabiner is hooked onto the connecting stud 55e. By rotatably connecting the first fixed part 16 and the tensioning mechanism 20 with the joint part 55 in this way, twisting of the wire 20b during operation of the robot 12 can be suppressed, and the load applied to the tensioning mechanism 20 (main body part 20a) can be reduced.

[0031] FIG. 7 is an enlarged view of the second fixing portion. As shown in FIG. 7, the second fixing portion 18 is formed by a second cable cover fixing device 52. The second cable cover fixing device 52 is fixed to the vertical frame 45a of the safety fence 45 by screws or the like. The second cable cover fixing device 52 fixes the cable cover 38 in a state where it grips the cable cover 38. The second cable cover fixing device 52 may have the same structure as the first cable cover fixing device 51 (FIG. 6). Also, as shown in FIG. 3, when the portion that fixes one end 14a of the cable 14 to the robot hand unit 28 is defined as the third fixing portion 19, the third fixing portion 19 may be formed by a third cable cover fixing device 53. The third cable cover fixing device 53 may have the same structure as the first cable cover fixing device 51.

[0032] FIG. 8 is a block diagram showing the configuration of a robot control system in the pickup device. In FIG. 8, the control unit 60 is a robot controller that controls the operation of the robot 12. The control unit 60 is electrically connected to six motors 61, 62, 63, 64, 65, and 66. The six motors 61 to 66 are drive sources for operating the robot 12, which is a six-axis robot. The control unit 60 supplies motor current to each of the motors 61, 62, 63, 64, 65, and 66. The control unit 60 also monitors the motor current supplied to each of the motors 61, 62, 63, 64, 65, and 66. The control unit 60 also limits the rotation angle of the wrist 26 and the robot hand 28 to a predetermined range so that excessive load is not applied to the cable 14 (particularly the first cable portion 41) during operation of the robot 12.

[0033] FIG. 9 is a flowchart showing the procedure of the robot control process. First, the control unit 60 supplies motor current to each of the motors 61, 62, 63, 64, 65, and 66, causing the robot 12 to perform a pick-and-place operation (step S1).

[0034] Next, the control unit 60 monitors the motor current supplied to each of the motors 61, 62, 63, 64, 65, and 66 (step S2). The motor current corresponds to the load applied to the tensioning mechanism 20 while the robot 12 is operating. The reason for this is as follows: if, for example, the tensioning mechanism 20 breaks and the wire 20b becomes locked while the robot 12 is operating, the wire 20b becomes tightly pulled, increasing the load applied to the tensioning mechanism 20. Furthermore, if the wire 20b becomes tightly pulled, the load applied to the robot 12 also increases, and therefore the motor current supplied to each of the motors 61, 62, 63, 64, 65, and 66 increases. Therefore, the magnitude of the load applied to the tensioning mechanism 20 can be detected from the motor current. Note that the load applied to the tensioning mechanism 20 may also be detected using a parameter other than the motor current.

[0035] Next, the control unit 60 determines whether the value of any of the motor currents supplied to the motors 61, 62, 63, 64, 65, and 66 has exceeded a predetermined threshold (step S3). A motor current value exceeding the threshold corresponds to a load of a predetermined value or more being applied to the tensioning mechanism 20 while the robot 12 is operating. The threshold should be set to a value that does not apply an excessive load to the cable 14. The threshold should be set for each motor 61, 62, 63, 64, 65, and 66 according to the specifications of the individual motors.

[0036] If the motor currents supplied to the motors 61, 62, 63, 64, 65, and 66 are all less than the threshold value (No in step S3), the control unit 60 proceeds to step S4.

[0037] Next, in step S4, the control unit 60 determines whether pick and place of all components has been completed. If pick and place of all components has not been completed (No in step S4), the control unit 60 returns to step S1 and causes the robot 12 to continue the pick and place operation. If pick and place of all components has been completed (Yes in step S4), the control unit 60 ends the series of processes at that point.

[0038] Furthermore, if the value of any of the motor currents supplied to the motors 61, 62, 63, 64, 65, and 66 is equal to or greater than the threshold value (if Yes in step S3), the control unit 60 immediately stops the operation of the robot 12 (step S5) and then ends the series of processes. At this time, the control unit 60 may perform a process to notify the worker that the operation of the robot 12 has been stopped (emergency stop) because a load equal to or greater than a predetermined value has been applied to the tensioning mechanism 20. Possible notification processes include, for example, a process to sound an alarm, a process to turn on or flash a warning light, a process to send alarm information to the worker's mobile device, etc.

[0039] In this way, by stopping the operation of the robot 12 when the motor current value exceeds a threshold value while the robot 12 is operating, it is possible to prevent excessive load from being applied to the cable 14 due to damage to the tensioning mechanism 20, etc.

[0040] As described above, in the first embodiment of the present invention, the cable 14 is connected to the robot 12 from outside the robot 12. Therefore, there is no need to newly design the robot 12 to match the layout of the cable 14. In other words, the robot 12 may be an existing robot, including a general-purpose robot. Furthermore, in the first embodiment of the present invention, tension is applied to the first cable portion 41, which is close to the robot hand unit 28, by the tensioning mechanism 20 via the first fixing portion 16, and slack is provided to the second cable portion 42, which is farther from the robot hand unit 28. This reduces the likelihood of the cable 14 interfering with the robot 12 or surrounding objects during operation of the robot 12, and also reduces the likelihood of excessive force being applied to the cable 14. This reduces damage to the cable 14 caused by the operation of the robot 12. Therefore, according to the first embodiment of the present invention, the robot 12 can be used for a long period of time while suppressing damage to the cable 14, and a low-cost, highly versatile pickup device 10 can be realized.

[0041] Furthermore, in the first embodiment of the present invention, the first fixed part 16 and the second fixed part 18 are both arranged outside the robot operation range 15. This makes it possible to prevent the robot hand part 28 from interfering with the first fixed part 16 or the second fixed part 18 while the robot 12 is operating.

[0042] Furthermore, in the first embodiment of the present invention, the second cable portion 42 is arranged outside the robot operation range 15. This makes it possible to prevent the robot hand unit 28 from interfering with the second cable portion 42 while the robot 12 is operating.

[0043] Second Embodiment FIG. 10 is a schematic diagram showing the configuration of a pickup device according to the second embodiment of the present invention. In the pickup device 10A according to the second embodiment, the robot 12 is provided so as to be movable in the horizontal direction H. The tensioning mechanism 20 and the second fixed portion 18 are attached to a support member 70. The support member 70 is movably attached to a guide rail 72. The guide rail 72 is arranged above the robot 12 in an orientation parallel to the horizontal direction H, which is the movement direction of the robot 12. As in the first embodiment, the first fixed portion 16, the second fixed portion 18, the tensioning mechanism 20, and the second cable portion 42 are arranged outside the robot operation range 15.

[0044] In the pickup device 10A configured as described above, when the robot 12 moves in the horizontal direction H, the support member 70 moves along the guide rail 72. Therefore, the tensioning mechanism 20 and the second fixing part 18 attached to the support member 70 move in the horizontal direction H to follow the movement of the robot 12. As a result, even when the robot 12 moves, the load applied to the cable 14 can be suppressed, and damage to the cable 14 can be reduced.

[0045] <Modifications, etc.> The technical scope of the present invention is not limited to the above-described embodiments, but also includes forms in which various modifications and improvements are made within the scope that can derive specific effects obtained by the constituent elements of the invention or by a combination of those constituent elements.

[0046] For example, in the above embodiment, the robot 12 is a six-axis robot, but the present invention is not limited to this, and a robot other than a six-axis robot may be used. [Explanation of symbols]

[0047] 10...Pickup device 12...Robot 14…Cable 15...Robot operating range 16...First fixed part 18…Second fixed part 20...Tensioning mechanism 28...Robot Hand Section 32...Camera 34…Lighting equipment 36…Cable wiring 38...Cable cover 41...First cable section 42...Second cable section 51...First cable cover fixing device 52...Second cable cover fixing device 55...Joint part 60...Control unit

Claims

1. a robot having a robot hand; a cable connected to the robot from outside the robot; a first fixing portion fixed to the cable outside the robot; a second fixing portion fixed to the cable at a position farther from the robot hand unit than the first fixing portion; a tension applying mechanism that applies tension to a first cable portion between the robot hand unit and the first fixed unit via the first fixed unit; a plurality of motors for operating the robot; a control unit that monitors a motor current supplied to the motor and stops the operation of the robot when a load equal to or greater than a predetermined value is applied to the tension applying mechanism during operation of the robot; Equipped with A second cable portion between the first fixed portion and the second fixed portion is maintained in a slack state. Pickup device.

2. The first fixed portion and the second fixed portion are each disposed outside a robot motion range. The pickup device according to claim 1 .

3. The second cable portion is positioned outside the robot's operating range.

3. The pickup device according to claim 1 or 2.

4. The horizontal position of the tension applying mechanism is near the center of the robot's operating range. The pickup device according to any one of claims 1 to 3.

5. A joint portion that rotatably connects the first fixed portion and the tension applying mechanism is provided. The pickup device according to any one of claims 1 to 4.

6. The cable includes a predetermined number of cable wirings and a cable cover that encloses the cable wirings, The pickup device according to any one of claims 1 to 5, wherein each of the first fixing portion and the second fixing portion is fixed to the cable cover.

7. A first cable cover fixture constituting the first fixing portion and a second cable cover fixture constituting the second fixing portion are fixed to the cable cover. The pickup device according to claim 6.

8. The cable is connected to the robot from the side opposite to the orientation of the robot hand unit. The pickup device according to any one of claims 1 to 7.

9. One end of the cable is connected to the robot hand unit. The pickup device according to any one of claims 1 to 8.

10. The robot is movably provided, The tension applying mechanism and the second fixing part are provided to be movable so as to follow the movement of the robot. The pickup device according to any one of claims 1 to 9.

11. The tension applying mechanism is constituted by a spring balancer. The pickup device according to any one of claims 1 to 10.

12. The cable has a cable wiring connected to an electronic device mounted on the robot hand unit. The pickup device according to any one of claims 1 to 11.

13. The electronic device includes at least one of a motor for a robot hand, a camera, and a lighting device. The pickup device according to claim 12.

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