WO2025057425A1 - Robot hand, transfer robot, and method for holding workpiece - Google Patents

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

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

One type of robot hand has multiple claws. Patent Document 1 discloses the following regarding the robot hand:

A robot hand that grasps and manipulates an object with multiple grasping fingers (claws) is characterized by having multiple grasping fingers including at least one grasping finger having a grasping surface made of a curved portion and a grasping surface made of a flat portion, an opening/closing drive mechanism that opens and closes each of the grasping fingers, and a mechanism that can change the grasping surface of the grasping fingers that comes into contact with the object depending on the shape of the object.

JP 2018-126806 A

Robot hands that grip a workpiece with multiple jaws have the problem of unstable gripping of the workpiece, causing the gripped workpiece to move or fall when being carried. This is particularly problematic when the robot hand is carrying multiple workpieces at once or when carrying workpieces with asymmetric shapes.

(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 operations, and the biasing mechanism stabilizes the holding of the one or more workpieces by the plurality of claws by elastically pressing the one or more workpieces against an inner wall of the claws.
In addition, holding a workpiece inside the multiple claws means, for example, as shown in Figure 5, storing one or more workpieces in the internal space of the multiple claws and maintaining the state of the workpieces so that they do not fall.

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 stably hold the workpiece. In particular, when holding multiple workpieces at once, the workpieces are closely in contact with each other while overlapping each other, improving stability.

(2) In the robot hand described in (1), the biasing mechanism may include an expansion member located inside the multiple claws, and may be a mechanism that elastically presses one or more of the workpieces against the inner wall of the claws by supplying air to expand the expansion member.

In this configuration, the elasticity of the expansion member can prevent excessive stress from being applied to a part of the workpiece. This reduces damage to the workpiece.

(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 claw portions when in an expanded state inside the claw portions.

In this configuration, the bulging surface fills the gap between the claws, preventing the workpiece from falling through the gap.

(4) In the robot hand described in (1), the biasing mechanism may include a biasing plate located inside the multiple claws, and may be a mechanism for pressing one or more of the workpieces against the inner wall of the claw by moving the biasing plate in a direction from the attachment member side toward the tip of the claw.

The technology disclosed in this specification can be applied to a transfer robot equipped with a robot hand. The technology disclosed in this specification can also be applied to a method of holding a workpiece.

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

Diagram showing the configuration of the transfer robot Side view of a robotic hand with its jaws closed Bottom view of the robot hand with the jaws closed Side view of a robotic hand with its claws open Bottom view of the robot hand with the claws open Cross-section of a robot hand FIG. 1 is a diagram showing a state before the balloon member is inflated; FIG. 13 is a diagram showing the state after the balloon member is inflated. Flowchart of workpiece transfer operation Diagram showing the workpiece transfer operation Side view of a robotic hand with its jaws closed Diagram showing the opening and closing structure of the claw Diagram showing the structure of the drive unit that opens and closes the claw Diagram showing the structure of the drive unit that opens and closes the claw Side view of a robotic hand

<Embodiment 1>
1. Transfer robot 10
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.

The control unit 11A controls the robot body 13, the robot hand 20, and the air supply device 17. The memory unit 11B stores the control program for the transfer robot 10 and data required to execute the control program.

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 shown as an example, and the robot body 13 includes a rotating table 14 and a robot arm 15.

The robot body 13 is motor-driven to control the posture and direction of the robot arm 15, allowing the robot hand 20 attached to the tip of the robot arm 15 to be moved to any position.

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.

The robot hand 20 is attached to the tip of the robot arm 15 and grasps 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, claw 31 will be used as a general term for the three claws 31A to 31C.

FIGS. 2A and 3A are side views of the robot hand 20, and FIGS. 2B and 3B are bottom views of the robot hand 20. FIG. 2 shows the claw portion 31 in an open state, and FIG. 3 shows the claw portion 31 in a closed state.

The mounting member 21 has a lower base 21A, an upper base 21B, a connecting wall 21C, and a storage section 21D.

The lower base 21A and upper base 21B are circular, with the upper base 21B located 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.

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.

The storage section 21D is located at the bottom of the lower base 21A. The storage section 21D is cylindrical with an open bottom. The balloon member 41, which will be described later, is stored in the center of the storage wall 21D.

The drive unit 23 consists of a hollow motor 25, a screw gear 26, and three helical gears 27A to 27C.

The hollow motor 25 is attached to the underside of the upper base 21B. The screw gear 26 is located at the bottom of 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 have shaft holes that penetrate vertically, and an air tube 45 is arranged inside.

In addition, 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.

As shown in FIG. 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 bent inward.

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

When the hollow motor 25 is driven, the screw gear 26 and the helical gears 27A-27C each rotate, causing the three links 35 to rotate around axis C. As a result, the three claws 31A-31C rotate around axis C together with the three links 35, making it possible to control the three claws 31A-31C between an open state (see Figure 2) and a closed state (see Figure 3).

When the three claws 31A to 31C are closed (see Figure 3), the bent tips 32 are close to each other, allowing the workpiece W to be held inside the three claws 31A to 31C.

The biasing mechanism 40 elastically presses the workpiece W held by the robot hand 20 against the inner walls 33 of the claws 31A, 31B, and 31C, thereby stabilizing the holding of the workpiece W by the robot hand 20.

Embodiment 1 discloses a biasing mechanism 40 that uses a balloon member 41. As shown in FIG. 4, the biasing mechanism 40 is made up of a balloon member 41 and an air tube 45. The balloon member 41 is an example of the "expansion member" of the present invention.

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

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.

By supplying air through the air tube 45, the balloon member 41 can be inflated inside the three claws 31A to 31C, as shown in Figure 3. By releasing or sucking the air from the balloon member 41, the inflated balloon member 41 can be deflated.

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

As shown in FIG. 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).

The three bulging surface portions 43A, 43BC, and 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.

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

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

When the transfer operation starts, the control unit 11A first moves the robot hand 20 to above the tray T1. Then, the three claws 31A to 31C of the robot hand 20 are opened, and the robot hand 20 is lowered toward the bulk-stacked workpieces W (S10).

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

Then, 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). This makes it possible to hold some of the multiple workpieces W stacked in bulk inside the three claws 31A to 31C (S20, see FIG. 5A).

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

By supplying air, the balloon member 41 expands inside the three claws 31A to 31C, pressing 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 workpiece W, increasing the stability of the workpiece W held by the robot hand 20.

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

Then, 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 in the balloon member 41. This causes the balloon member 41 to return from the expanded state to the deflated state (S50).

Then, 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). This releases the robot hand 20 from its grip, and the multiple workpieces W fall onto the tray T2 (S60).

By repeating this operation, multiple workpieces W stacked randomly on tray T1 can be transferred to tray T2.

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, making it possible to stably hold the workpieces W by the robot hand 20. Therefore, it is possible to prevent the workpieces W from falling off the robot hand 20 during transportation.

In addition, because this configuration uses a balloon member 41 in the biasing mechanism 40, the elasticity of the balloon member 41 can prevent excessive stress from being applied to a part of the workpiece W when it is held by the robot hand 20. This reduces damage to the workpiece W.

In addition, this configuration allows the bulging surface portions 43AB, 43BC, and 43CA to fill the gaps between the claws, preventing the workpiece W from falling through the gaps between the claws while the workpiece W is being transported.

In addition, 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 deflating the balloon member 41 before opening the claws 31A to 31C, the elasticity of the balloon member 41 can be prevented from scattering the workpiece W around when the claws 31A to 31C are opened.

<Embodiment 2>
The first embodiment discloses the biasing mechanism 40 using the balloon member 41. The second embodiment discloses the biasing mechanism 140 using the biasing plate 141.

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

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

The cylinder body 144 is cylindrical and houses a piston 145 inside. The rod 146 is attached to the piston 145.

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 storage section 21D.

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 back and forth in the vertical direction via the rod 146.

Therefore, as shown in FIG. 8, when the biasing plate 141 is moved downward (toward the tip 32 of the claw portion 31), the biasing plate 141 presses the multiple workpieces W against the inner wall 33 of the claw portion 31. This makes it possible to stably hold the workpieces W by the robot hand 20.

<Embodiment 3>
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.

Figure 10 shows one form of the drive unit 240 that opens and closes the claw portion 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 portion 31 attached to the tip of the screw shaft 245 to be opened and closed.

<Other embodiments>
The technology disclosed in this specification is not limited to the embodiments described above and illustrated in the drawings, and for example, the following embodiments are also included within the technical scope.

(1) In the above embodiment 1, 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 just one. For example, this can be used when transferring a workpiece W whose posture is difficult to stabilize when held by the robot hand 20, such as an asymmetrical shape.

(2) In the above embodiment 1, 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 embodiment 1. They may be shovel-shaped or spoon-shaped.

(3) In the above embodiment 2, an air cylinder 143 is used to drive the biasing plate 141, but a motor or the like may also be used.

(4) In the above embodiment 1, the robot hand 20 has a structure that does not have finger joints. As shown in FIG. 11, the robot hand 320 may have a structure that has finger joints 331 and 332.

(5) In the above embodiment 1, the balloon member 41 is used to bias the workpiece W held by the robot hand 20. 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 air is supplied thereto can be used.

(6) In the above embodiment 1, 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 the workpieces and controlling its size (balloon volume). For example, the number of workpieces held can be reduced by inflating the balloon member 41 significantly and reducing the volume of the hand. Conversely, the number of workpieces held can be increased by inflating the balloon member 41 only slightly and increasing the volume of the hand.

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

Claims (7)

A robotic hand,
A mounting member;
A plurality of claw portions attached to the mounting member in an openable and closable manner;
a biasing mechanism attached to the mounting member,
The plurality of claw portions hold one or a plurality of workpieces inside the plurality of claw portions by opening and closing operations,
The robot hand, wherein the biasing mechanism stabilizes the holding of the one or more workpieces by the multiple claw portions by elastically pressing the one or more workpieces against the inner walls of the claw portions. The robot hand according to claim 1 ,
The biasing mechanism of the robot hand includes an expansion member positioned inside the multiple claw portions, and elastically presses one or more of the workpieces against the inner wall of the claw portion by supplying air to expand the expansion member. The robot hand according to claim 2,
The robot hand, wherein the expansion member has a plurality of bulging surface portions that bulge toward the gaps between the claw portions when in an expanded state inside the claw portions. The robot hand according to claim 1 ,
The robot hand is a mechanism in which 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. A transfer robot,
The robot hand according to any one of claims 1 to 4,
a robot body that moves the robot hand to an arbitrary position;
A transfer robot including a control unit. The transfer robot according to claim 5,
The control unit is
One or more workpieces are held inside the claws by the claws of the robot hand,
The one or more workpieces held by the plurality of claw portions are elastically pressed against inner walls of the plurality of claw portions by the biasing mechanism;
The transfer robot then begins the operation of lifting the one or more workpieces held by the multiple claw portions. A method for holding one or more workpieces, comprising:
One or more workpieces are held by a plurality of claws on the inner side of the plurality of claws,
A method for holding a workpiece, comprising: elastically pressing one or more workpieces held by a plurality of claw portions against an inner wall of the claw portion using a biasing mechanism, thereby stabilizing the holding of the one or more workpieces by the plurality of claw portions.

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