Robot hand, transfer robot, and method for holding workpiece

Abstract

Provided is a robot hand 20 comprising: an attachment member 21; a plurality of claw portions 31A-31C which are attached to the attachment member 21 and which can be opened and closed; and a biasing mechanism 40 which is attached to the attachment member 21. The plurality of claw portions 31A-31C hold one or more workpieces W inside the plurality of claw portions by an opening and closing action. The biasing mechanism 40 elastically presses the one or more workpieces W toward inner walls 33 of the claw portions 31A-31C so as to stabilize holding of the one or more workpieces W by the plurality of claw portions 31A-31C.

Description

Robot hand, transfer robot, and workpiece holding method

[0001] The technology disclosed in this specification relates to a technology for holding a workpiece.

[0002] One type of robot hand has multiple claws. Patent Document 1 discloses the following regarding a robot hand.

[0003] The robot hand, which grasps and manipulates an object using multiple grasping fingers (claw portions), is characterized by comprising multiple grasping fingers, including at least one grasping finger having a grasping surface consisting of a curved portion and a grasping surface consisting of a flat portion, an opening / closing drive mechanism for opening and closing each of the grasping fingers, and a mechanism capable of changing the grasping surface of the grasping fingers that comes into contact with the object depending on the shape of the object.

[0004] Japanese Patent Application Laid-Open No. 2018-126806

[0005] Robot hands that grip workpieces with multiple jaws have the problem of unstable workholding, causing the gripped workpiece to move or fall when being transported, especially when the robot hand is transporting multiple workpieces at once or workpieces with asymmetric shapes.

[0006] (1) A robot hand disclosed in this specification includes a mounting member, a plurality of claws attached to the mounting member in an openable and closable manner, and a biasing mechanism attached to the mounting member. The plurality of claws hold one or more workpieces inside the plurality of claws by opening and closing the plurality of claws, and the biasing mechanism elastically presses the one or more workpieces against inner walls of the claws, thereby stabilizing the holding of the one or more workpieces by the plurality of claws. Note that holding a workpiece inside the plurality of claws means, for example, as shown in FIG. 5, storing one or more workpieces in the internal space of the plurality of claws and maintaining the state of the workpieces so that they do not fall.

[0007] In this configuration, the biasing mechanism elastically presses the workpiece against the inner wall of the claw, generating a moderate frictional force between the claw and the workpiece. This allows the robot hand to hold the workpiece stably. In particular, when holding multiple workpieces at once, the workpieces are closely attached to each other while overlapping, improving stability.

[0008] (2) In the robot hand described in (1), the biasing mechanism may be a mechanism that includes an expansion member located inside the plurality of claw portions, and that elastically presses one or more of the workpieces against the inner wall of the claw portion by expanding the expansion member through the supply of air.

[0009] In this configuration, the elasticity of the expansion member can prevent excessive stress from being applied to a part of the workpiece, thereby reducing damage to the workpiece.

[0010] (3) In the robot hand described in (2), the expansion member may have a plurality of bulging surface portions that bulge toward the gaps between the plurality of claw portions when expanded inside the plurality of claw portions.

[0011] In this configuration, the bulging surface fills the gaps between the claws, making it possible to prevent the workpiece from falling through the gaps between the claws.

[0012] (4) In the robot hand described in (1), the biasing mechanism may include a biasing plate located inside the plurality of claw portions, and may be a mechanism that presses one or more of the workpieces against the inner wall of the claw portion by moving the biasing plate in a direction from the mounting member side toward the tip of the claw portion.

[0013] The technology disclosed in this specification can be applied to a transfer robot equipped with a robot hand, and also to a method for holding a workpiece.

[0014] The configuration of the present invention allows the robot hand to stably hold the workpiece.

[0015] Diagram showing the configuration of a transfer robotSide view of a robot hand with the claws closedBottom view of a robot hand with the claws closedSide view of a robot hand with the claws openBottom view of a robot hand with the claws openCross-section of a robot handDiagram showing the state before inflation of a balloon memberDiagram showing the state after inflationFlowchart of workpiece transfer operationDiagram showing the workpiece transfer operationSide view of a robot hand with the claws closedDiagram showing the opening and closing structure of the clawsDiagram showing the structure of a drive unit that opens and closes the clawsDiagram showing the structure of a drive unit that opens and closes the clawsSide view of a robot hand

[0016] 1, the transfer robot 10 includes a controller 11, a robot body 13, an air supply device 17, and a robot hand 20. The controller 11 includes a control unit 11A and a storage unit 11B.

[0017] The control unit 11A controls the robot body 13, the robot hand 20, and the air supply device 17. The storage unit 11B stores a control program for the transfer robot 10 and data required for executing the control program.

[0018] The robot body 13 is, for example, an industrial robot such as a SCARA robot or an articulated robot. In this embodiment, an articulated robot is exemplified, and the robot body 13 includes a rotating base 14 and a robot arm 15.

[0019] The robot body 13 is motor-driven to control the posture and direction of the robot arm 15, thereby being able to move the robot hand 20 attached to the tip of the robot arm 15 to any position.

[0020] The air supply device 17 is connected to a balloon member (described later) 41 of the robot hand 20 via an air hose 17A, and supplies air to the balloon member 41.

[0021] The robot hand 20 is attached to the tip of the robot arm 15 and grips the workpiece W. The robot hand 20 has an attachment member 21, a drive unit 23, three claws 31A to 31C, and a biasing mechanism 40. Hereinafter, the claw 31 will be referred to collectively as the three claws 31A to 31C.

[0022] 2A and 3A are side views of the robot hand 20, and 2B and 3B are bottom views of the robot hand 20. Fig. 2 shows a state in which the claws 31 are open, and Fig. 3 shows a state in which the claws 31 are closed.

[0023] The mounting member 21 has a lower base 21A, an upper base 21B, a connecting wall 21C, and a housing portion 21D.

[0024] The lower base 21A and the upper base 21B are circular, with the upper base 21B positioned above the lower base 21A. A joint 22 to which the air hose 17A is connected is attached to the top surface of the upper base 21B.

[0025] The connecting wall 21C is located on the outer periphery of the lower base 21A and the upper base 21B, and connects the two bases 21A and 21B vertically.

[0026] The housing portion 21D is located below the lower base 21A. The housing portion 21D is cylindrical with an open bottom. A balloon member 41 (described later) is housed in the center of the housing wall 21D.

[0027] The drive unit 23 is made up of a hollow motor 25, a screw gear 26, and three helical gears 27A to 27C.

[0028] The hollow motor 25 is attached to the underside of the upper base 21B. The screw gear 26 is located below the hollow motor 25 and is connected to the motor shaft of the hollow motor 25. The hollow motor 25 and the screw gear 26 are formed with a shaft hole that passes through them vertically, and an air tube 45 is disposed inside.

[0029] Three helical gears 27A to 27C are rotatably attached to the upper surface of the lower base 21A. The three helical gears 27A to 27C are arranged at equal intervals (120-degree intervals) and each meshes with the screw gear 26. The screw gear 26 and the helical gear 27 form a worm gear.

[0030] 2, the three claws 31A, 31B, and 31C are disposed at equal intervals (120-degree intervals) on the lower base 21A. The three claws 31A, 31B, and 31C have tip portions 32 that are bent inward.

[0031] The three claws 31A, 31B, and 31C are attached to the three helical gears 27A to 27C of the lower base 21A via links 35, respectively.

[0032] When the hollow motor 25 is driven, the screw gear 26 and the helical gears 27A to 27C each rotate, causing the three links 35 to rotate around the axis C. As a result, the three claws 31A to 31C rotate integrally with the three links 35 around the axis C, and the three claws 31A to 31C can be controlled to an open state (see FIG. 2) or a closed state (see FIG. 3).

[0033] When the three claws 31A to 31C are closed (see FIG. 3), the bent tip portions 32 are close to each other, so that the workpiece W can be held inside the three claws 31A to 31C.

[0034] The biasing mechanism 40 stabilizes the holding of the workpiece W by the robot hand 20 by elastically pressing the workpiece W held by the robot hand 20 against the inner walls 33 of the claw portions 31A, 31B, and 31C.

[0035] The first embodiment discloses a biasing mechanism 40 that uses a balloon member 41. As shown in Fig. 4, the biasing mechanism 40 is made up of the balloon member 41 and an air tube 45. The balloon member 41 is an example of the "expansion member" of the present invention.

[0036] The balloon member 41 is a bag-shaped member made of an elastic material such as rubber. The balloon member 41 is attached to the inside of the three claws 31A to 31C, specifically, to the center of the storage section 21D. The balloon member 41 has an air inlet 42 for introducing air.

[0037] The air tube 45 passes vertically through the upper base 21B, the shaft hole of the hollow motor 25, the shaft hole of the screw gear 26, and the lower base 21A. One end of the air tube 45 is connected to the joint 22 on the top surface of the upper base, and the other end is connected to the air supply port 42 of the balloon member 41.

[0038] 3, the balloon member 41 can be inflated inside the three claws 31A to 31C by supplying air through the air tube 45. The inflated balloon member 41 can be deflated by releasing or sucking the air from the balloon member 41.

[0039] To release the air from the balloon member 41, for example, a valve provided on the air supply path may be opened to the atmosphere. To suck in the air, a diffuser or the like may be used to apply negative pressure to the balloon member 41 through the air supply path.

[0040] 3, the balloon member 41 has three bulging surface portions 43AB, 43BC, and 43CA. The three bulging surface portions 43AB, 43BC, and 43CA are provided on the outer surface of the balloon member 41 at equal intervals (120 degree intervals).

[0041] The three bulging surface portions 43A, 43BC, 43CA are located between the claw portions 31, and when the balloon member 41 is inflated, they bulge out from the surface of the balloon member 41 to fill the gaps between the claw portions 31.

[0042] Specifically, the bulging surface portion 43AB fills the gap between the claw portion 31A and the claw portion 31B, the bulging surface portion 43BC fills the gap between the claw portion 31B and the claw portion 31C, and the bulging surface portion 43CA fills the gap between the claw portion 31C and the claw portion 31A.

[0043] 3. Transferring Operation of Workpiece W Figure 6 is a flowchart of the transferring operation of workpiece W, and Figure 7 is an explanatory diagram of the transferring operation of workpiece W. In this embodiment, a case will be described in which a plurality of workpieces (e.g., screws, bolts, etc.) W stacked in bulk on tray T1 are transferred to tray T2 (see Figure 1). Before the operation starts, balloon member 41 is stored in storage section 21D in a deflated state.

[0044] When the transfer operation starts, the control unit 11A first moves the robot hand 20 above the tray T1, then opens the three claws 31A to 31C of the robot hand 20 and lowers the robot hand 20 toward the bulk-stacked workpieces W (S10).

[0045] As the robot hand 20 descends, the tip portions 32 of the claws 31A to 31C are inserted into the workpieces W randomly piled on the tray T1.

[0046] Thereafter, the control unit 11A operates the drive unit 23 to switch the claws 31A to 31C from the open state (the state in FIG. 2) to the closed state (the state in FIG. 3). As a result, some of the multiple workpieces W stacked in bulk can be held inside the three claws 31A to 31C (S20, see FIG. 5A).

[0047] Thereafter, the control unit 11A drives the air supply device 17 to supply air to the balloon member 41 of the robot hand 20.

[0048] When air is supplied, the balloon members 41 expand inside the three claws 31A to 31C and press the workpiece W against the inner walls 33 of the claws 31A to 31C (see FIG. 5B). This brings the workpiece W into close contact with the inner walls 33, thereby increasing the stability of the workpiece W held by the robot hand 20.

[0049] Next, the control unit 11A raises the robot hand 20 holding the plurality of workpieces W, and then moves it above the tray T2 (S40).

[0050] Thereafter, the control unit 11A lowers the robot hand 20 above the tray T2. When the robot hand 20 has lowered to a predetermined height, the control unit 11A releases the air from the balloon member 41. As a result, the balloon member 41 returns from the inflated state to the deflated state (S50).

[0051] Thereafter, the control unit 11A operates the drive unit 23 to switch the claws 31A to 31C from the closed state (the state in FIG. 3) to the open state (the state in FIG. 2), thereby releasing the robot hand 20 from its grip, and the multiple workpieces W fall onto the tray T2 (S60).

[0052] By repeating this operation, multiple works W stacked in bulk on the tray T1 can be transferred to the tray T2.

[0053] 3. Description of Effects In this embodiment, the biasing mechanism 40 presses multiple workpieces W held by the robot hand 20 against the inner walls 33 of the claws 31A to 31C. This generates an appropriate frictional force between the claws 31 and the workpieces W, stabilizing the holding of the workpieces W by the robot hand 20. This makes it possible to prevent the workpieces W from falling off the robot hand 20 during transportation.

[0054] Furthermore, this configuration uses the balloon member 41 in the biasing mechanism 40, so when the workpiece W is held by the robot hand 20, the elasticity of the balloon member 41 can prevent excessive stress from being applied to a part of the workpiece W. Therefore, damage to the workpiece W can be reduced.

[0055] In addition, in this configuration, the bulging surface portions 43AB, 43BC, 43CA fill the gaps between the claw portions, so that the workpiece W can be prevented from falling through the gaps between the claw portions while being transported.

[0056] Furthermore, with this configuration, when releasing the workpiece W from the robot hand 20, the balloon member 41 is deflated before the claws 31A to 31C are opened. By opening the claws 31A to 31C after deflating the balloon member 41, the elasticity of the balloon member 41 can be prevented from scattering the workpiece W around when the claws 31A to 31C are opened.

[0057] Second Embodiment The first embodiment discloses a biasing mechanism 40 using a balloon member 41. The second embodiment discloses a biasing mechanism 140 using a biasing plate 141.

[0058] The biasing mechanism 140 includes a biasing plate 141 and an air cylinder 143. The biasing plate 141 is disk-shaped and is housed inside the three claws 31A to 31C, specifically in the housing portion 21D of the mounting member 21.

[0059] The air cylinder 143 is attached to the top surface of the upper base 21B, and includes a cylinder body 144, a piston 145, a rod 146, and a coil spring 147.

[0060] The cylinder body 144 has a cylindrical shape and houses therein a piston 145. The rod 146 is attached to the piston 145.

[0061] The rod 146 passes through the bottom wall of the cylinder body 144, the shaft hole of the hollow motor 25, the shaft hole of the screw gear 26, and the lower base 21A, and is connected to the biasing plate 141 of the accommodation portion 21D.

[0062] The coil spring 147 is fitted onto the outer periphery of the rod 146 inside the cylinder body 144. By supplying air to the cylinder body 144, the biasing plate 141 can be moved up and down reciprocally via the rod 146.

[0063] 8, when the biasing plate 141 is moved downward (toward the tip 32 of the claw 31), the biasing plate 141 presses the multiple workpieces W against the inner wall 33 of the claw 31. This allows the robot hand 20 to stably hold the workpieces W.

[0064] Third Embodiment In the first and second embodiments, the claw portion 31 is opened and closed by rotating the link 35. As shown in Fig. 9, the claw portion 31 can also be opened and closed by a sliding movement in an oblique direction.

[0065] 10 shows one embodiment of a drive unit 240 that opens and closes the claw 31. The drive unit 240 is composed of a motor 241, a gear 243, and a screw shaft 245. When the motor 241 is driven, power is transmitted via the gear 243, and the screw shaft 245 moves in an oblique direction. This allows the claw 31 attached to the tip of the screw shaft 245 to be opened and closed.

[0066] Other Embodiments The technology disclosed in this specification is not limited to the embodiments described above and illustrated with reference to the drawings, and the following embodiments, for example, are also included within the technical scope.

[0067] (1) In the above-described first embodiment, an example is shown in which multiple workpieces W are transferred by the robot hand 20. The number of workpieces W to be transferred is not limited to multiple, and may be one. For example, this can be used when transferring a workpiece W that is difficult to stabilize when held by the robot hand 20, such as one with an asymmetrical shape.

[0068] (2) In the first embodiment, the number of claws 31 is three. The number of claws 31 may be two, or four or more. The shape of the claws 31 is not limited to the shape disclosed in the first embodiment. They may be shovel-shaped or spoon-shaped.

[0069] (3) In the second embodiment, the air cylinder 143 is used to drive the biasing plate 141, but a motor or the like may also be used.

[0070] (4) In the first embodiment, the robot hand 20 has no finger joints. As shown in FIG. 11 , the robot hand 320 may have finger joints 331 and 332.

[0071] (5) In the first embodiment, the workpiece W held by the robot hand 20 is biased using the balloon member 41. The biasing of the workpiece W is not limited to the balloon member 41, and any member that expands to increase its surface area when supplied with air can be applied.

[0072] (6) In the first embodiment, the balloon member 41 is used to bias the workpiece W held by the robot hand 20. The balloon member 41 can also be used to adjust the number of workpieces W held by the robot hand 20. Specifically, the number of workpieces W held can be adjusted by inflating the balloon member 41 inside the robot hand before holding a workpiece and controlling its size (balloon volume). For example, the number of workpieces W can be reduced by inflating the balloon member 41 too much and reducing the volume of the hand. Conversely, the number of workpieces can be increased by inflating the balloon member 41 only slightly and increasing the volume of the hand.

[0073] REFERENCE SIGNS LIST 10 Transfer robot 11 Controller 13 Robot body 20 Robot hand 21 Mounting member 23 Drive unit 31A to 31C Claw portion 40 Urging mechanism 41 Balloon member (expanding member) 43AB, 43BC, 43CA Bulging surface portion 45 Air tube 140 Urging mechanism 141 Urging plate 143 Air cylinder

Claims

1. A robot hand comprising: a mounting member; a plurality of claw portions attached to the mounting member in an openable and closable manner; and a biasing mechanism attached to the mounting member, wherein the plurality of claw portions hold one or more workpieces inside the plurality of claw portions by opening and closing actions, and the biasing mechanism stabilizes the holding of the one or more workpieces by the plurality of claw portions by elastically pressing the one or more workpieces against the inner walls of the claw portions.

2. A robot hand as described in claim 1, wherein the biasing mechanism includes an expansion member positioned inside the multiple claw portions, and is a mechanism for elastically pressing one or more of the workpieces against the inner wall of the claw portion by expanding the expansion member through the supply of air.

3. A robot hand as described in claim 2, wherein the expansion member has a plurality of bulging surface portions which bulge toward the gaps between the plurality of claw portions when in an expanded state inside the plurality of claw portions.

4. A robot hand as described in claim 1, wherein the biasing mechanism includes a biasing plate located inside the multiple claw portions, and the biasing plate is moved in a direction from the mounting member side toward the tip of the claw portion to press one or more of the workpieces against the inner wall of the claw portion.

5. A transfer robot comprising: a robot hand according to any one of claims 1 to 4; a robot body that moves the robot hand to an arbitrary position; and a control unit.

6. A transfer robot as described in claim 5, wherein the control unit: holds one or more workpieces inside the multiple claw portions of the robot hand; elastically presses the one or more workpieces held by the multiple claw portions against the inner walls of the multiple claw portions by the biasing mechanism; and then initiates an operation of lifting up the one or more workpieces held by the multiple claw portions.

7. A method for holding one or more workpieces, comprising: holding one or more workpieces inside a plurality of claw portions with the plurality of claw portions; and elastically pressing the one or more workpieces held by the plurality of claw portions against the inner walls of the claw portions with a biasing mechanism, thereby stabilizing the holding of the one or more workpieces by the plurality of claw portions.

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