A biomimetic soft gripper based on an elephant trunk

Abstract

This invention discloses a biomimetic soft gripper based on an elephant trunk, comprising: a flexible mechanism and at least two soft pneumatic actuators. The flexible mechanism has a notch and an internal cavity. The at least two soft pneumatic actuators are disposed within the cavity of the flexible mechanism and are evenly arranged along the circumference of the wall of the notch. Each soft pneumatic actuator is connected to a first air tube. After each soft pneumatic actuator draws negative pressure, it bends towards and compresses the wall of the notch. This invention can effectively adapt to objects of different shapes during gripping and improves gripping stability.

Description

Technical Field

[0001] This invention relates to the field of robotics, and more particularly to a biomimetic soft gripper based on an elephant trunk. Background Technology

[0002] During a robot's grasping task, contact between a hard gripper and a hard object can cause impact, potentially damaging the object or pushing it off its intended path. A widely adopted solution is to add flexible materials to the robot's end effector, using "soft grippers" for grasping. Soft grippers are classified into three types based on their actuation method: driven grippers, variable stiffness grippers, and controllable adhesion grippers. Current soft grippers generally suffer from two major problems: firstly, their applicability is not wide enough; secondly, the gripping force cannot be kept constant.

[0003] A flexible pneumatic actuator is a typical soft gripper. Due to its elasticity and deformability, it can achieve various complex shape changes, thus generating different motion modes such as extension, bending, and torsion. The movement of a flexible pneumatic actuator is usually controlled by adjusting the inflow and outflow of gas. It can also be precisely operated using manual, electronic, or automatic control systems. Flexible pneumatic actuators possess high flexibility, adapting to different working environments and tasks. Compared to traditional rigid mechanical structures, their structural design is more flexible, and the materials are lighter. However, due to structural limitations, flexible pneumatic actuators are not fully compatible with the size of the objects they grip, limiting their applicability.

[0004] Suction cups are a typical type of soft gripper, offering fast and reliable grasping capabilities. These grippers are widely used for repetitive and predictable pick-and-place tasks, particularly in highly integrated and automated factories. However, to extend this capability to tasks with greater variation or more agile factory environments, the inherent limitations of suction cups must be overcome. Suction cups have limitations in terms of the size of objects they can pick up; objects typically need to be at least as large as the suction cup aperture. Furthermore, surface textures and irregularities lead to significant vacuum pressure losses, making it impossible to maintain a constant holding force.

[0005] Therefore, those skilled in the art are dedicated to providing a biomimetic soft gripper based on an elephant trunk, which can not only effectively adapt to different shapes of objects during the gripping process, but also achieve high gripping stability. Summary of the Invention

[0006] In view of the deficiencies in the prior art, the technical problem to be solved by the present invention is how to provide a soft gripper that can adapt to objects of different shapes and improve gripping stability.

[0007] To achieve the above objectives, the present invention provides a biomimetic soft gripper based on an elephant trunk, comprising: a flexible mechanism and at least two soft pneumatic actuators. The flexible mechanism has a notch and an interior cavity. The at least two soft pneumatic actuators are disposed within the cavity of the flexible mechanism and are evenly arranged along the circumference of the wall of the notch. Each soft pneumatic actuator is connected to a first air tube. After each soft pneumatic actuator draws negative pressure, it bends towards the wall of the notch and squeezes the wall of the notch.

[0008] Preferably, the flexible mechanism is made of silicone.

[0009] Preferably, the notch is in the shape of an inverted funnel.

[0010] Preferably, each of the soft pneumatic actuators includes a base, a plurality of supports located on one side of the base, and a sealing cloth. The supports are connected to the base at intervals, and the sealing cloth is wrapped around the outside of the base and the supports, forming a sealed cavity inside the sealing cloth. One end of the first air tube is placed inside the sealed cavity of the sealing cloth.

[0011] Preferably, the base and the support are made of silicone.

[0012] Furthermore, it also includes a base connected to one end of the flexible mechanism, the base sealing the cavity of the flexible mechanism; the first air tube passes through the base.

[0013] Furthermore, the cavity of the flexible mechanism is filled with blocking particles.

[0014] Preferably, it further includes a second air tube that passes through the base, with one end of the second air tube located inside the cavity.

[0015] Preferably, it further includes a third air tube, which passes through the base and one end of the third air tube is located in the recess.

[0016] Preferably, the flexible mechanism and the soft pneumatic actuator are made using a mold.

[0017] The present invention has at least the following beneficial technical effects:

[0018] The biomimetic soft gripper based on an elephant trunk provided by this invention can achieve multimodal gripping: the adhesion force is controlled by a suction cup, the stiffness of the soft suction cup is changed by particle blocking, and a soft pneumatic actuator is embedded to achieve precise gripping, so that the soft gripper can adapt to diverse task requirements.

[0019] The biomimetic soft gripper based on an elephant trunk provided by this invention introduces an adjustable stiffness mechanism, solving the problem of insufficient gripping force in flexible grippers, thus enabling it to have stronger gripping ability while maintaining flexibility. The biomimetic soft gripper with both stiffness and flexibility can improve gripping ability and adaptability while protecting objects from damage.

[0020] The biomimetic soft gripper based on an elephant trunk provided by this invention, through the precise design and coordinated use of its components, enables the biomimetic soft gripper to exhibit extremely high efficiency and stability in practical applications.

[0021] The following will further explain the concept, specific structure, and technical effects of the present invention in conjunction with the accompanying drawings, so as to fully understand the purpose, features, and effects of the present invention. Attached Figure Description

[0022] Figure 1 This is an assembly diagram of the elephant trunk-based bionic soft gripper according to an embodiment of the present invention.

[0023] Figure 2 This is a schematic diagram of the base according to an embodiment of the present invention;

[0024] Figure 3 This is a schematic diagram of a soft pneumatic actuator according to an embodiment of the present invention;

[0025] Figure 4 This is a schematic diagram of the inner and outer silicone molds according to an embodiment of the present invention.

[0026] In the figure, 1-flexible mechanism, 11-notch, 12-cavity, 2-base, 3-first air pipe, 4-soft pneumatic actuator, 41-base, 42-support body, 5-blocking particle, 6-connecting component, 7-second air pipe, 8-third air pipe. Detailed Implementation

[0027] The preferred embodiments of the present invention are described below to make the technical content clearer and easier to understand. The present invention can be embodied in many different forms, and the scope of protection of the present invention is not limited to the embodiments mentioned herein.

[0028] In the accompanying drawings, components with the same structure are indicated by the same numerical designation, and components with similar structures or functions are indicated by similar numerical designations. The dimensions and thicknesses of each component shown in the drawings are arbitrary, and the present invention does not limit the dimensions and thicknesses of each component. To make the illustrations clearer, the thickness of some components has been appropriately exaggerated in the drawings.

[0029] This invention, inspired by the two finger-like protrusions at the end of an elephant's trunk, employs a biomimetic design to provide a biomimetic soft gripper based on the elephant's trunk. Addressing the limited application of single-mode grippers, this biomimetic soft gripper utilizes a multi-modal grasping scheme. It controls adhesion through a suction cup and alters the stiffness of the suction cup by incorporating particle blocking, enabling various grasping modes such as pinching, wrapping, and clamping. To address the issue of inconsistent gripping force, a gripper design combining rigidity and flexibility is employed, with an embedded pneumatic actuator for precise grasping. This biomimetic soft gripper combines the gripping method of an elephant's trunk with the advantages of pneumatic actuators, solving the problem of robust gripping of objects of different shapes, surfaces, and sizes. It not only effectively adapts to different object shapes but also achieves high gripping stability. Compared to traditional rigid grippers, the biomimetic soft gripper offers greater diversity in form and structure.

[0030] like Figure 1 As shown, in a specific embodiment of the present invention, the bionic soft gripper has at least a flexible mechanism 1 and a soft pneumatic actuator 4. The flexible mechanism 1 has a notch 11, which is inverted funnel-shaped; the interior of the flexible mechanism 1 is a cavity 12. The soft pneumatic actuator 4 is disposed in the cavity 12 and is arranged circumferentially along the wall of the notch 11; when the soft pneumatic actuator 4 is evacuated to a vacuum, it bends and bends towards the wall of the notch 11, applying pressure to the wall of the notch 11. After the wall of the notch 11 is compressed, it can act on the object inside the notch 11 to grasp the object. A first air pipe 3 is connected to the soft pneumatic actuator 4, through which negative pressure is applied to the soft pneumatic actuator 4.

[0031] In this embodiment, the flexible mechanism 1 is made of silicone material. Using silicone material can ensure that the flexible mechanism 1 has appropriate rigidity. The flexibility and elasticity of silicone allow it to closely fit the surface of the object being grasped, thereby improving the stability and reliability of the grasping.

[0032] like Figure 3 As shown, the soft pneumatic actuator 4 in this embodiment is approximately finger-shaped, having a base 41 resembling a palm and multiple supports 42 resembling fingers, with the supports 42 spaced apart on one side of the base 41. A sealing cloth is wrapped around the outer sides of the base 41 and the supports 42. Specifically, in this embodiment, the sealing cloth is wrapped around the sides of the base 41 and the supports 42, sealingly connecting the sealing cloth to the base 41 and the supports 42, thus forming a sealed cavity between the sealing cloth and the two supports 42 at the beginning and end. Figure 3 In the view shown, the head support 42 has holes, allowing the first air tube 3 to be inserted into the sealed cavity and draw negative pressure for the soft pneumatic actuator 4. To improve the effect of drawing negative pressure, holes are also made in the middle support 42, allowing communication between the internal spaces.

[0033] The soft pneumatic actuator 4 is made of silicone, enabling it to produce soft motion, thus adapting to objects of different shapes and providing better gripping performance. Silicone adhesive is used to adhere the first air tube 3 where it passes through the support body 42, ensuring no gas leakage at the connection point; the sealing cloth is also connected to the base 41 and support body 42 using adhesive. The base 41 and support body 42 are integrally molded.

[0034] There are multiple flexible pneumatic actuators 4, which are evenly distributed around the circumference of the wall of the recess 11. When the flexible pneumatic actuator 4 bends, it simultaneously squeezes the wall of the recess 11 to grip the object. In this embodiment, there are two flexible pneumatic actuators 4, which are diagonally distributed along the wall of the recess 11.

[0035] like Figure 1 As shown, a base 2 is provided at the end of the cavity 12 of the flexible mechanism 1. The base 2 is sealed to the flexible mechanism 1 to achieve the sealing of the cavity 12. Figure 2 As shown, the base 2 has multiple holes for multiple air tubes to pass through it.

[0036] The cavity 12 of the flexible mechanism 1 is filled with blocking particles 5, which fill the space of the cavity 12. The blocking particles 5 can be grains such as millet or other lightweight particles. A second air pipe 7 runs through the base 2, with one end of the second air pipe 7 placed inside the cavity 12, allowing for vacuuming of the cavity 12. The blocking particles 5 have a filling function, preventing the first air pipe 3 from becoming blocked due to deformation when vacuuming is performed, thus ensuring the stability and reliability of the system. The blocking particles 5 also have a stiffness adjustment function; through contact with the wall of the recess 11 and the flexible pneumatic actuator 4, they increase the stiffness of the wall of the recess 11 and simultaneously harden the flexible pneumatic actuator 4, thereby increasing its holding force.

[0037] like Figure 1 As shown, a third air pipe 8 also runs through the base 2. One end of the third air pipe 8 is connected to the notch 11. A vacuum can be drawn through the third air pipe 8 to make the notch 11 a suction cup, which can then adsorb objects at the end of the flexible mechanism 1, thereby achieving multimodal grasping. The presence of the blocking particles 5 can increase the stiffness of the suction cup; the hybrid mode, in conjunction with the soft pneumatic actuator 4, can change the aperture of the suction cup, further adapting to the grasping of different objects.

[0038] The base 2 is also equipped with several connecting components 6 for connecting the first air pipe 3, the second air pipe 7, the third air pipe 8, and the base 2. The connections are sealed to ensure a tight seal within the cavity 12. The connecting components 6 include adhesives, bolts, nuts, etc. One end of the soft pneumatic actuator 4 is fixed to the base 2 via the connecting components 6.

[0039] In this embodiment, the biomimetic soft gripper, flexible mechanism 1, and soft pneumatic actuator 4 are molded using a mold and silicone injection molding. Figure 4 The image shows a 3D printed mold. This mold processing method ensures that the flexible mechanism 1 and the soft pneumatic actuator 4 have appropriate rigidity.

[0040] The bionic soft gripper of this embodiment features an operation control system that includes vacuum pressure control and motion control of the soft pneumatic actuator 4. The vacuum pressure of the suction cup and cavity 12 is controlled by a solenoid valve, and a regulator limits the pressure within the suction cup to ensure the vacuum level is lower than that of the cavity 12. This prevents the suction cup wall from collapsing inward during startup and ensures sufficient holding force. Simultaneously, compressed air controls the movement of the soft pneumatic actuator 4 via a proportional valve, maintaining a constant pressure within the cavity 12 and keeping it below the level at which the actuator 4 might burst. This precise pressure control system ensures stable operation of the soft pneumatic actuator 4 under various operating conditions, providing reliable gripping performance. Through this structure and control method, the multimodal bionic soft gripper offers excellent gripping capabilities when facing objects of different shapes, surfaces, and sizes. The precise design and coordinated use of each component enable the bionic soft gripper to exhibit extremely high efficiency and stability in practical applications.

[0041] In implementing multimodal hybrid grasping, algorithmic constraints can be combined to enable the robot to select a grasping strategy based on the shape and size of the object. This strategy is based on three basic shapes: cylinder, sphere, and cuboid. By identifying individual primitives in the object and extracting their dimensions, a prediction algorithm is used to select a grasping mode with strong matching. For each basic shape, size constraints are defined for each grasping mode to achieve successful grasping based on simple geometric parameter prediction.

[0042] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A biomimetic soft gripper based on an elephant trunk, characterized in that, include: The system comprises a flexible mechanism, at least two flexible pneumatic actuators, a base, a second air pipe, and a third air pipe. The flexible mechanism has a notch and an internal cavity. The at least two flexible pneumatic actuators are disposed within the cavity of the flexible mechanism and are evenly arranged along the circumference of the wall of the notch. Each flexible pneumatic actuator is connected to a first air pipe. After each flexible pneumatic actuator draws negative pressure, it bends towards and compresses the wall of the notch. The base is connected to one end of the flexible mechanism and seals the cavity of the flexible mechanism. The first air pipe passes through the base. The second air tube passes through the base, with one end of the second air tube located inside the cavity; the third air tube passes through the base, with one end of the third air tube located inside the recess; the cavity of the flexible mechanism is filled with blocking particles.

2. The elephant trunk-based bionic soft gripper as described in claim 1, characterized in that, The flexible mechanism is made of silicone.

3. The elephant trunk-based bionic soft gripper as described in claim 1, characterized in that, The notch is shaped like an inverted funnel.

4. The elephant trunk-based bionic soft gripper as described in claim 1, characterized in that, Each of the soft pneumatic actuators includes a base, a plurality of supports located on one side of the base, and a sealing cloth. The supports are connected to the base at intervals. The sealing cloth is wrapped around the outside of the base and the supports, forming a sealed cavity inside the sealing cloth. One end of the first air tube is placed inside the sealed cavity of the sealing cloth.

5. The elephant trunk-based bionic soft gripper as described in claim 4, characterized in that, The base and the support are made of silicone.

6. The elephant trunk-based bionic soft gripper as described in claim 1, characterized in that, The flexible mechanism and the soft pneumatic actuator are made using molds.

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