Based on pneumatic flexible pinching multi-working condition gripper

Abstract

The present invention provides a pneumatic flexible pinching multi-working-mode gripper, comprising: a rigid pressure-bearing cover, a rigid sealing ring, a flexible air cavity, and a plurality of flexible multi-material fingers; the rigid sealing ring and the flexible air cavity are arranged in the rigid pressure-bearing cover, and the flexible air cavity is sealed on the rigid pressure-bearing cover by the rigid sealing ring; an air source input hole is provided on the rigid pressure-bearing cover, and the air source input hole is connected to the flexible air cavity; one end of the flexible multi-material finger is connected to the flexible air cavity, and the end of the flexible multi-material finger away from the flexible air cavity is set as a gripping end. The flexible pinching multi-working-mode gripper of the present invention has a compact structure, is lightweight, is easy to drive, and is suitable for grasping fragile or delicate objects in a small space.

Description

Technical Field

[0001] The present invention relates to the technical field of soft robots, and in particular to a pneumatic flexible pinching multi-working-mode gripper. Background Art

[0002] A soft pneumatic gripper is a robotic gripper composed of a soft material with a low Young's modulus. Its structure deforms under a certain pressure to achieve gripping. Soft pneumatic grippers exhibit strong adaptability in their interaction with the external environment, eliminating the need for additional force feedback controllers. They can adapt their shape to the object they interact with and are less likely to damage it. Therefore, they are often used in industrial automation to grip fragile items such as jewelry, eggs, and compact powder.

[0003] When it comes to grasping small or fragile items in confined spaces, current robotic end-point grippers lack the advantages of being lightweight, compact, simple to drive, and flexible, creating the risk of collision damage to both the environment and the robot. This often requires additional control costs for the end-point grippers as a remedy. Furthermore, current soft robot designs often struggle to balance factors like gripping force and deformation range. Consequently, they often fall short of ideal performance in practical applications, leaving room for improvement.

[0004] Patent document with publication number CN207027311U discloses a new type of flexible chuck, comprising a clamping portion and a connecting portion made of elastic material, wherein the clamping portion comprises at least two mutually cooperating fingertips for clamping, with a finger gap formed between each fingertip, and a finger cavity provided inside each fingertip, the connecting portion comprising a connecting cavity, which is connected to each finger cavity, and a connecting port provided on the connecting portion that communicates with the connecting cavity, the fingertip comprising an inner wall near the finger gap and an outer wall away from the finger gap, the thickness of the inner wall being less than that of the outer wall, or the elastic modulus of the inner wall being less than that of the outer wall. However, the thin-walled structural design of the patent document itself determines that the upper limit of the output force is low when the material modulus and the driving air pressure are not changed.

[0005] Patent document CN109015724A discloses a pneumatic soft gripper comprising a pneumatic soft actuator and a clamping device. The pneumatic soft actuator is a hollow cylindrical structure with an air cavity and a semicircular cross-section. Three pneumatic soft actuators are evenly distributed around the circumference of the gripper. One end of each pneumatic soft actuator is fixed to a designed clamping device. Under the action of air pressure, the free end bends toward the center of the circle, and the three pneumatic soft actuators work together to achieve grasping. However, this patent document suffers from limited gripping space and a limited range of objects that can be grasped.

[0006] Patent document CN111360866B discloses a pneumatic soft gripper with an automatically adjustable workspace, comprising a palm opening and closing mechanism, a top connector, and multiple pneumatic soft fingers. The palm opening and closing mechanism is positioned above the multiple pneumatic soft fingers, and the top connector is positioned above the palm opening and closing mechanism and is securely connected to the palm opening and closing mechanism. The pneumatic soft fingers comprise a multi-cavity actuator, a soft strain sensor, and a connecting base. The soft strain sensor is securely connected to the multi-cavity actuator, which is securely connected to the connecting base. However, this patent document suffers from the drawback of being unable to balance factors such as gripping output force and deformation stroke. Summary of the Invention

[0007] In view of the defects in the prior art, the purpose of the present invention is to provide a pneumatic flexible pinching multi-working mode gripper.

[0008] According to the present invention, a pneumatic flexible pinching multi-working mode gripper is provided, comprising: a rigid pressure-bearing cover, a rigid sealing ring, a flexible air cavity, and a plurality of flexible multi-material fingers;

[0009] The rigid sealing ring and the flexible air cavity are arranged in the rigid pressure-bearing cover, and the flexible air cavity is sealed on the rigid pressure-bearing cover by the rigid sealing ring; an air source input hole is provided on the rigid pressure-bearing cover, and the air source input hole is connected to the flexible air cavity;

[0010] One end of the flexible multi-material finger is connected to the flexible air cavity, and one end of the flexible multi-material finger away from the flexible air cavity is configured as a grasping end.

[0011] Preferably, the flexible air cavity is provided with a bottom rotating surface for connecting the flexible multi-material finger;

[0012] The flexible multi-material finger is provided with a revolving curved surface adapted to the bottom revolving surface; the flexible multi-material finger is connected and arranged on the flexible air cavity through the revolving curved surface and the bottom revolving surface.

[0013] Preferably, the bottom revolving surface is a curved surface with a concave middle and a convex edge.

[0014] Preferably, the rigid pressure-bearing cover and the flexible air cavity are arranged in a cylindrical shape as a whole;

[0015] The flexible multi-material fingers are arranged in a wedge shape as a whole; there are three flexible multi-material fingers, and the three flexible multi-material fingers are arranged in a circumferential array on the flexible air cavity.

[0016] Preferably, the bottom revolving surface and the revolving curved surface are bonded together.

[0017] Preferably, the rigid pressure-bearing cover is provided with a first connecting hole;

[0018] The peripheral side wall of the flexible multi-material finger close to one end of the flexible air cavity is connected to the rigid pressure-bearing cover through the first connecting hole.

[0019] Preferably, the gas source input hole also serves as a second connection hole, and an external mobile device is connected to the rigid pressure cover through the second connection hole;

[0020] The rigid pressure-bearing cover is provided with a third connecting hole, and the rigid sealing ring clamps the flexible air cavity and is arranged on the rigid pressure-bearing cover through the third connecting hole.

[0021] Preferably, the flexible multi-material finger comprises a soft structure and a reinforcement structure;

[0022] The soft structure is made of Agilus30 Clear material, and the reinforcement structure is made of a mixture of VeroBlackPlus material and Agilus30 Clear material.

[0023] Preferably, the rigid pressure-bearing cover and the rigid sealing ring are made of resin material;

[0024] The flexible air cavity is made of polyurethane rubber casting with a shear modulus of 0.5 MPa;

[0025] The flexible multi-material finger is manufactured in one piece using a multi-material polymer jet 3D printing process, and contains a combination of materials with multiple moduli, with the material shear modulus ranging from 0.2 MPa to 15 MPa.

[0026] Preferably, when positive pressure is applied to the flexible air cavity, the expansion of the flexible air cavity causes the plurality of flexible multi-material fingers to open;

[0027] When negative pressure is introduced into the flexible air cavity, the contraction of the flexible air cavity causes the plurality of flexible multi-material fingers to collapse.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. The pneumatically driven flexible pinching multi-mode gripper disclosed herein is in a retracted state when no driving air pressure is present, making it easy to access narrow spaces. The three flexible fingers are simultaneously driven by a single air cavity at the base, simplifying the operation. The gripper operates under either positive or negative pressure, allowing it to operate in two different modes to accommodate objects with different shapes. For example, positive pressure can be used to support objects with holes, such as vials, bearings, and nuts; negative pressure can be used to grip objects from the outside.

[0030] 2. This invention combines topology optimization design methods with an additive manufacturing process using multi-material polymer injection. The gripper can output a large grasping force under both positive and negative pressure. At 160kPa, the blocking force of a single finger can reach 1.6N, and at -80kPa, it can reach -0.9N.

[0031] 3. The gripper of the present invention is compact and lightweight, and is suitable for use as an end effector of a robot. The gripper has a size of 40*40*73mm and a total weight of 89g. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0033] Figure 1 This is a structural diagram of the pneumatic flexible pinching multi-working mode gripper of the present invention;

[0034] Figure 2 is a structural diagram of the flexible multi-material finger of the present invention;

[0035] Figure 3 This is an assembly cross-sectional view of the pneumatic flexible pinching multi-working mode gripper of the present invention;

[0036] Figure 4 It is an exploded view of the assembly of the pneumatic flexible pinching multi-working mode gripper of the present invention.

[0037] The figure shows:

[0038] Rigid pressure cover 1 Flexible air cavity 3

[0039] Airtight bolt 101 Bottom rotating surface 301

[0040] Fixing bolt 102 Flexible multi-material finger 4

[0041] Air source input hole 103 reinforcement structure 401

[0042] First connection hole 104 Software structure 402

[0043] Rigid sealing ring 2 revolution surface 403 DETAILED DESCRIPTION

[0044] The present invention will be described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several changes and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0045] Example 1:

[0046] like Figures 1 to 4 As shown, this embodiment provides a pneumatic flexible pinching multi-working condition gripper, including: a rigid pressure cover 1, a rigid sealing ring 2, a flexible air cavity 3 and a plurality of flexible multi-material fingers 4, the rigid sealing ring 2 and the flexible air cavity 3 are arranged in the rigid pressure cover 1, the flexible air cavity 3 is sealed on the rigid pressure cover 1 through the rigid sealing ring 2, an air source input hole 103 is provided on the rigid pressure cover 1, the air source input hole 103 is connected to the flexible air cavity 3, one end of the flexible multi-material finger 4 is connected to the flexible air cavity 3, and the end of the flexible multi-material finger 4 away from the flexible air cavity 3 is set as a gripping end.

[0047] When positive pressure is applied to the flexible air cavity 3 , the expansion of the flexible air cavity 3 causes the multiple flexible multi-material fingers 4 to open; when negative pressure is applied to the flexible air cavity 3 , the contraction of the flexible air cavity 3 causes the multiple flexible multi-material fingers 4 to close.

[0048] A first connection hole 104 is provided on the rigid pressure-bearing cover 1 , and the peripheral side wall of the flexible multi-material finger 4 close to one end of the flexible air cavity 3 is connected to the rigid pressure-bearing cover 1 through the first connection hole 104 .

[0049] The air source input hole 103 also serves as the second connection hole. The external mobile device is connected to the rigid pressure cover 1 through the second connection hole. The rigid pressure cover 1 is provided with a third connection hole. The rigid sealing ring 2 clamps the flexible air cavity 3 on the rigid pressure cover 1 through the third connection hole.

[0050] The flexible air cavity 3 is provided with a bottom rotating surface 301 for connecting the flexible multi-material finger 4, and the flexible multi-material finger 4 is provided with a rotating curved surface 403 adapted to the bottom rotating surface 301. The flexible multi-material finger 4 is connected to the flexible air cavity 3 through the rotating curved surface 403 and the bottom rotating surface 301.

[0051] The rigid pressure-bearing cover 1 and the flexible air chamber 3 are cylindrical in shape, while the flexible multi-material fingers 4 are wedge-shaped. Three flexible multi-material fingers 4 are arranged in a circular array on the flexible air chamber 3. The bottom revolving surface 301 and the revolving curved surface 403 are bonded together. The bottom revolving surface 301 is a curved surface with a concave center and convex edges.

[0052] The flexible multi-material finger 4 includes a soft structure 402 and a reinforcement structure 401 . The soft structure 402 is made of Agilus30Clear material, and the reinforcement structure 401 is made of a mixture of VeroBlackPlus material and Agilus30 Clear material. The VeroBlackPlus material and Agilus30 Clear material are mixed in a certain ratio.

[0053] The rigid pressure cover 1 and the rigid sealing ring 2 are made of resin material, the flexible air cavity 3 is made of polyurethane rubber casting with a shear modulus of 0.5 MPa, and the flexible multi-material finger 4 is made of one-piece molding using a multi-material polymer injection 3D printing process. It contains a combination of materials with multiple moduli, and the material shear modulus covers the range of 0.2 MPa to 15 MPa.

[0054] Working principle:

[0055] When the air source enters the flexible air cavity 3 through the air source input hole 103, since the bottom rotating surface 301 is a curved surface with a concave middle and a convex edge, if the input pressure is positive, the center of the bottom rotating surface 301 will bulge toward the grasping end of the gripper. When the bottom rotating surface 301 is deformed, it will drive the rotating curved surface 403 of the flexible multi-material finger 4 bonded to it. The edge of the flexible multi-material finger 4 is fixed by the first connecting hole 104 of the rigid pressure-bearing cover 1. Under the constraint of this boundary condition and the loading of force, the flexible multi-material finger 4 will cause the end finger to produce an opening action. On the contrary, if the input pressure is negative, the above deformation direction is opposite, which will cause the end finger to produce a closing action.

[0056] Example 2:

[0057] Those skilled in the art may understand this embodiment as a more specific description of Embodiment 1.

[0058] like Figures 1 to 4 As shown, this embodiment provides a pneumatic flexible pinching multi-working condition gripper, including a rigid pressure cover 1, a rigid sealing ring 2, a flexible air cavity 3, flexible multi-material fingers 4 and bolt fasteners and other structures.

[0059] The rigid pressure cover 1 is cylindrical in shape as a whole and has a threaded hole on its top for connecting to the outside (such as a robotic arm) and serving as an air source input hole 103. A circle of through holes is arranged around the hole for connecting to the rigid sealing ring 2, which is fixed by airtight bolts 101. The bottom of the rigid pressure cover 1 has bolt holes arranged 120 degrees circumferentially for fixing the flexible multi-material fingers 4, which are fixed by fixing bolts 102.

[0060] The rigid sealing ring 2 is annular in shape and has eight threaded holes spaced 45 degrees apart around the circumference for connection to the rigid pressure cover 1. Once assembled, the sealing ring clamps the flexible air chamber 3, forming a complete airtight structure with the rigid pressure cover 1.

[0061] The flexible air chamber 3, which is generally cylindrical, is embedded in the rigid pressure cover 1. Its bottom surface is a curved surface with a concave center and a convex edge, representing the bottom revolved surface 301. This surface is bonded to the mating surface (i.e., revolved surface 403) at the top of the flexible multi-material finger 4. This component is also secured by three bolts arranged 120 degrees around the bottom circumference of the rigid pressure cover 1.

[0062] The flexible multi-material finger 4 is composed of three identical individual flexible fingers arranged in a circular array, appearing to be gathered together. The flexible finger is wedge-shaped overall, with a long aspect ratio. A revolved surface 403 is located at its top, bonded to the curved bottom surface of the flexible air cavity 3. The multi-material finger is primarily composed of Agilus30 Clear material, with a small portion of reinforcement structure composed of a mixture of VeroBlackPlus and Agilus30 Clear materials in a specific ratio. The reinforcement structure extends from the top curved surface to the finger tip, exhibiting symmetry but possessing complex topological connections.

[0063] The internal material distribution of the flexible multi-material finger 4 is designed using structural topology optimization technology, with the maximum working stroke as the design goal, while taking into account the interactive force of the object on the gripper during grasping.

[0064] The rigid pressure cover 1 and rigid sealing ring 2 are made of a high-strength resin material. The flexible air chamber 3 is cast from polyurethane rubber with a shear modulus of approximately 0.5 MPa. The flexible multi-material finger 4 is integrally molded using a multi-material polymer injection 3D printing process. It contains a combination of materials with a shear modulus ranging from 0.2 MPa to 15 MPa.

[0065] The pneumatic flexible pinching gripper has two working states. When positive pressure is applied to the flexible air cavity 3, the expansion of the air cavity causes the flexible multi-material fingers 4 to open; when negative pressure is applied, the air cavity contracts, causing the fingers to close.

[0066] This embodiment discloses a pneumatic flexible pinching multi-working condition gripper, comprising a rigid pressure-bearing cover 1, a rigid sealing ring 2, a flexible air cavity 3 and a flexible multi-material finger 4. The gripper body has a fingertip structural feature of three circumferential periodic arrays, and the flexible multi-material finger mating surface is glued to the flexible air cavity bottom rotary mating surface. The flexible multi-material finger and the flexible air cavity are assembled through the rigid pressure-bearing cover and the rigid sealing ring, and the pneumatic load is connected to the flexible air cavity through the pressure-bearing cover interface. The flexible multi-material finger is designed using a structural topology optimization method. The design variable is the topological distribution of the internal soft and hard materials, so that when the air pressure load of the flexible air cavity is transmitted, the optimal expansion and contraction functional effect and grasping performance can be produced at the end of the gripper. The multi-material flexible pinching multi-working condition gripper has a compact structure, light weight, and is easy to drive. It is suitable for grasping fragile or delicate objects in a small space.

[0067] Example 3:

[0068] Those skilled in the art may understand this embodiment as a more specific description of Embodiment 1.

[0069] This embodiment provides a pneumatic flexible pinching multi-working mode gripper. This pinching gripper adopts a structural topology optimization design method and an advanced multi-material additive manufacturing process, which greatly simplifies the structural shape and drive arrangement. This embodiment adopts the following technical solutions:

[0070] The pinching gripper includes a rigid pressure cover 1, a rigid sealing ring 2, a flexible air cavity 3, a flexible multi-material finger 4, and a bolt fastener. The rigid sealing ring 2 and the flexible air cavity 3 are embedded in the rigid pressure cover 1 to form a single-connected airtight chamber. During pressurization or vacuuming, only the rotating surface at the bottom of the flexible air cavity 3 is deformed. The flexible multi-material finger 4 is a solid structure without an internal cavity. Its multi-material distribution is obtained by the structural topology optimization design method. It fits the rotating surface of the flexible air cavity 3 and is fixed to the bolt hole at the bottom of the rigid pressure cover 1. The flexible finger adopts the polymer injection 3D printing process, which can define the soft and hard material distribution inside the structure as needed. During the design process, the goal is to maximize the opening and closing stroke of the finger under air pressure drive. At the same time, the interactive force from the object during grasping is taken into account to design the distribution of soft and hard materials inside the structure. In the preferred example, the Neo-Hookean hyperelastic material model is used to analyze its deformation response under air pressure, and the adjoint displacement method is used to solve its target sensitivity. For the optimization results, this embodiment adopts a voxel blending approach to approximate the physical properties of multiple materials and complete the post-processing flow.

[0071] The usage conditions of this embodiment can be explained as follows: its driving form is pneumatic drive. When positive pressure is introduced, the air cavity expands and pushes open the base of the gripper, and the three fingers open synchronously, with an ultimate pressure resistance of 180kPa; when negative pressure is introduced, the air cavity contracts and pulls the base of the gripper, and the three fingers close synchronously, with an ultimate pressure resistance of -100kPa.

[0072] Furthermore, the rigid pressure cover 1 and the rigid sealing ring 2 are made of a high-strength resin material.

[0073] Furthermore, the flexible air cavity 3 is cast from polyurethane rubber with a shear modulus of approximately 0.5 MPa.

[0074] Furthermore, the flexible multi-material finger 4 is integrally formed by a multi-material polymer injection 3D printing process, and the shear modulus of the internal material combination ranges from 0.2 MPa to 15 MPa.

[0075] The flexible pinching multi-working mode gripper of the present invention has a compact structure, is lightweight, and is easy to drive, and is suitable for grasping fragile or delicate objects in a narrow space.

[0076] In the description of this application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0077] The above describes specific embodiments of the present invention. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. The embodiments of this application and the features in the embodiments may be combined with each other in any manner unless there is a conflict.

Claims

1. A pneumatic flexible pinching multi-working mode gripper, characterized in that: include: A rigid pressure-bearing cover (1), a rigid sealing ring (2), a flexible air cavity (3), and a flexible multi-material finger (4); The rigid sealing ring (2) and the flexible air cavity (3) are arranged in the rigid pressure-bearing cover (1), and the flexible air cavity (3) is sealed on the rigid pressure-bearing cover (1) through the rigid sealing ring (2); an air source input hole (103) is provided on the rigid pressure-bearing cover (1), and the air source input hole (103) is connected to the flexible air cavity (3); One end of the flexible multi-material finger (4) is connected to the flexible air cavity (3), and one end of the flexible multi-material finger (4) away from the flexible air cavity (3) is set as a grasping end; The flexible air cavity (3) is provided with a bottom rotating surface (301) for connecting the flexible multi-material finger (4); The flexible multi-material finger (4) is provided with a revolving curved surface (403) adapted to the bottom revolving surface (301); the flexible multi-material finger (4) is connected to the flexible air cavity (3) via the revolving curved surface (403) and the bottom revolving surface (301); The bottom revolving surface (301) and the revolving curved surface (403) are bonded together; When positive pressure is introduced into the flexible air cavity (3), the expansion of the flexible air cavity (3) causes the plurality of flexible multi-material fingers (4) to open; When negative pressure is introduced into the flexible air cavity (3), the contraction of the flexible air cavity (3) causes the plurality of flexible multi-material fingers (4) to collapse; The bottom revolving surface (301) is a curved surface with a concave center and a convex edge; The rigid pressure-bearing cover (1) and the flexible air cavity (3) are arranged in a cylindrical shape as a whole; The flexible multi-material fingers (4) are arranged in a wedge shape as a whole; the flexible multi-material fingers (4) are arranged in three, and the three flexible multi-material fingers (4) are arranged in a circumferential array on the flexible air cavity (3).

2. The pneumatic flexible pinching multi-working mode gripper according to claim 1 is characterized in that: The rigid pressure-bearing cover (1) is provided with a first connecting hole (104); The peripheral side wall of the flexible multi-material finger (4) close to one end of the flexible air cavity (3) is connected to the rigid pressure-bearing cover (1) through the first connecting hole (104).

3. The pneumatic flexible pinching multi-working mode gripper according to claim 1 is characterized in that: The gas source input hole (103) also serves as a second connection hole, and an external mobile device is connected to the rigid pressure-bearing cover (1) via the second connection hole; The rigid pressure-bearing cover (1) is provided with a third connection hole, and the rigid sealing ring (2) clamps the flexible air cavity (3) through the third connection hole and is arranged on the rigid pressure-bearing cover (1).

4. The pneumatic flexible pinching multi-working mode gripper according to claim 1 is characterized in that: The flexible multi-material finger (4) comprises a soft structure (402) and a reinforcement structure (401); The soft structure (402) is made of Agilus30 Clear material, and the reinforcement structure (401) is made of a mixture of VeroBlackPlus material and Agilus30 Clear material.

5. The pneumatic flexible pinching multi-working mode gripper according to claim 1 is characterized in that: The rigid pressure-bearing cover (1) and the rigid sealing ring (2) are made of resin material; The flexible air cavity (3) is made of polyurethane rubber casting, and has a shear modulus of 0.5 MPa.

Images