Soft robot structure

Abstract

The application discloses a kind of soft manipulator structures, it includes hard connection base and at least three soft fingers;The root of soft finger is fixedly connected to the one end of hard connection base away from soft arm, and soft finger is distributed at preset angle along the circumference of hard connection base;Wherein, the inside of soft finger is distributed with multiple cell structures, cell structure is diamond cell, and diamond cell is unevenly arranged in the inside of soft finger;The inside of soft finger is provided with a reference axis eccentrically arranged, the reference axis extends along the length direction of finger and is located at the position close to the inside of hard connection base;Diamond cell is distributed radially along the radial direction of soft finger with reference axis as reference, and extends from reference axis to the outer circumferential side of soft finger, so that finger can be stably bent in the direction of near palm, and bending in the direction of far palm is limited.The application has the advantages of effectively preventing reverse flexion of soft finger, improving gripping stability and load capacity.

Description

Technical Field

[0001] This invention relates to the field of underwater robot grasping technology, and more specifically, to a soft manipulator structure. Background Technology

[0002] The demand for underwater operations, such as marine resource exploration, underwater archaeology, and biological sample collection, continues to grow. Underwater gripping devices, as the core end effector of operational robots, directly impact task performance. While traditional rigid manipulators possess high gripping force and positioning accuracy, they are prone to damaging underwater targets with fragile surfaces, irregular shapes, or soft materials, and struggle to adapt to complex, unstructured environments. Soft continuum gripping devices, with their high degrees of freedom, passive compliance, and environmental adaptability, are gradually becoming a research focus in the field of underwater operations. Existing soft gripping devices are mostly manufactured using silicone molding or thermoplastic polyurethane 3D printing. Their internal structures are often designed as uniformly distributed lattices or axially repeating cells, exhibiting isotropic bending stiffness characteristics. The driving methods primarily employ fluid actuation or multiple rope antagonistic traction, achieving target object envelopment through active control of finger deformation.

[0003] However, existing technologies have significant drawbacks in complex underwater environments. The isotropic design of the soft finger structure results in the same low stiffness characteristics in both the grasping direction (bending towards the palm) and the opposite force direction (facing away from the palm). When grasping heavy loads or encountering water currents, the fingers are prone to uncontrolled backward flexing, severely weakening grasping stability and load-bearing capacity. Furthermore, the single-configuration soft gripper lacks adaptive adjustment capabilities, making it unable to simultaneously achieve flexible approach over a large area and precise locking operation in a small area when facing targets with uncertain spatial positions and varying shapes. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a soft robotic hand structure that effectively prevents the reverse flexion of the soft fingers and improves grasping stability and load capacity.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A soft robotic hand structure includes a rigid connecting base and at least three soft fingers. The roots of the soft fingers are fixedly connected to the end of the rigid connecting base away from the soft forearm, and the soft fingers are distributed at a predetermined angle along the circumference of the rigid connecting base. Each soft finger contains multiple rhomboid cells, which are non-uniformly arranged within the soft finger. An eccentrically positioned reference axis is defined within the soft finger, extending along the length of the finger and located near the inner side of the rigid connecting base. The rhomboid cells are radially distributed along the radial direction of the soft finger, with the reference axis as a reference, and extend from the reference axis towards the outer periphery of the soft finger. The topological configuration of the rhomboid cells is configured such that the finger can be stably bent in the proximal direction, while bending is restricted in the distal direction.

[0006] As a preferred embodiment of the present invention, the rhomboid cell forms a porous structure on the sidewall of the soft finger, the porous structure being divided into at least two regions with different average bending stiffness in the circumferential direction of the soft finger; the at least two regions include a first region and a second region, the average bending stiffness of the first region being less than the average bending stiffness of the second region; the first region is located on the side closer to the palm, and the second region is located on the side farther from the palm.

[0007] As a preferred embodiment of the present invention, a longitudinal rib is provided at the center of the second region. The longitudinal rib extends along the length direction of the soft finger and penetrates the rhomboid cell in that direction. The longitudinal rib and the reference axis are located on the same plane.

[0008] In a preferred embodiment of the present invention, the number of soft fingers is three, arranged in a configuration of one short and two long soft fingers, with the two long soft fingers symmetrically arranged relative to the short soft fingers. A finger root soft body connects the short soft fingers to the rigid connecting base. The finger root soft body contains multiple cell structures, which are rhomboid cells, evenly distributed within the finger root soft body. These rhomboid cells are radially distributed along the radial direction of the finger root soft body, with the central axis as a reference, and extend from the central axis toward the outer periphery of the finger root soft body. The short soft fingers and the finger root soft body together form a soft thumb. The long soft fingers, the soft thumb, and the rhomboid cells within both are integrally printed from an elastic material.

[0009] In a preferred embodiment of the present invention, the length of the soft thumb is less than the length of the long soft finger; both the long soft finger and the soft thumb are tapered with a root diameter greater than a tip diameter.

[0010] As a preferred embodiment of the present invention, the soft robotic hand structure further includes a soft forearm, one end of which is a base connection end for connecting to an external mechanism; the other end of the soft forearm is connected to the end of the rigid connecting base away from the soft finger.

[0011] As a preferred embodiment of the present invention, the flexible forearm has a hollow, conical structure, and the diameter of its base connection end is larger than the diameter of the end near the rigid connection base; the sidewall of the flexible forearm has a mesh structure, and the sidewall of the flexible forearm is provided with a plurality of reinforcing ribs extending along the length direction of the flexible forearm, and the plurality of reinforcing ribs are evenly spaced along the circumference of the flexible forearm; the flexible forearm and the reinforcing ribs are integrally printed from an elastic material.

[0012] As a preferred embodiment of the present invention, the flexible forearm, the rigid connecting base, the long flexible finger, the short flexible finger, and the finger root soft body are all provided with channels through which drive ropes can pass, and the channels are made of plastic tubes; wherein, the number of channels for driving the bending of the flexible forearm is not less than 3, and they are evenly arranged along the circumference of the flexible forearm; the number of channels for driving the bending of the long flexible finger is two, and they are symmetrically arranged on both sides of the first region of the long flexible finger; the number of channels for driving the bending of the short flexible finger is two, and they are symmetrically arranged on both sides of the first region of the short flexible finger; the number of channels for driving the bending of the finger root soft body is not less than 3, and they are spaced apart along the circumference of the finger root soft body on the side of the finger root soft body facing the long flexible finger.

[0013] As a preferred embodiment of the present invention, the end sidewall of the soft forearm near the rigid connecting base, the end sidewall of the finger root soft body near the short soft finger, the end of the long soft finger, and the end of the short soft finger are all provided with anchoring holes adapted to the number of their own channels, and the anchoring holes are used to connect the drive rope.

[0014] As a preferred embodiment of the present invention, the soft forearm and the rigid connecting base, the rigid connecting base and the long soft finger, the rigid connecting base and the finger root soft body, and the finger root soft body and the short soft finger are all connected by end face flanges.

[0015] As can be seen from the above, the soft robotic hand structure of the present invention, compared with the prior art, has the following advantages: Through the non-uniformly arranged rhomboid cell structure inside the soft finger, radially distributed with an eccentric reference axis, it is configured to stably bend in the direction near the palm while restricting bending in the direction far from the palm, thereby effectively preventing reverse buckling. This solves the problem of reverse buckling instability of soft fingers when grasping heavy objects or encountering water flow impact, significantly improving the load stability of underwater operations. Therefore, the present invention has the advantages of effectively preventing reverse buckling of soft fingers and improving grasping stability and load capacity. Attached Figure Description

[0016] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0017] Figure 1 This is an isometric view of an embodiment of the present invention; Figure 2 This is an isometric view of a long, soft finger in an embodiment of the present invention; Figure 3 This is a side view of the long, soft finger in an embodiment of the present invention; Figure 4 This is an isometric view of a short, soft finger in an embodiment of the present invention; Figure 5 This is an isometric view of the finger root software in an embodiment of the present invention; Figure 6 This is an isometric view of the soft forearm in an embodiment of the present invention.

[0018] Explanation of markings in the diagram: Rigid connecting base 10; soft finger 20; long soft finger 20a; short soft finger 20b; finger root soft 20c; soft thumb 20d; rhomboid cell 21; longitudinal rib 22; first region 20A; second region 20B; soft forearm 30; base connecting end 31; mesh structure 32; reinforcing rib 33; channel 40; anchoring hole 50. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0020] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0021] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0022] In the description of this application, it should be noted that if terms such as "upper," "lower," "inner," or "outer" are used to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the invention is usually placed during use, they 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, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0023] Furthermore, the terms "first" and "second" are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0024] It should be noted that, where there is no conflict, the features in the embodiments of this application can be combined with each other.

[0025] Traditional underwater grasping devices are prone to damage when dealing with fragile, irregular, or soft targets. Furthermore, when grasping heavy loads or subjected to water flow impacts, the isotropic structure of the fingers can easily lead to reverse flexing, severely affecting grasping stability and load capacity. In addition, existing control strategies often require high power consumption to maintain attitude, resulting in high energy consumption and easy material fatigue and creep, making it difficult to meet the requirements of high-frequency, long-cycle underwater operations.

[0026] For this, see Figures 1 to 6 This invention proposes a soft robotic hand structure, which includes a rigid connecting base 10 and at least three soft fingers 20. The components work together to achieve stable underwater grasping. The specific structure and working principle are as follows: A rigid connecting base 10 is fixed to the other end of the flexible forearm 30, serving as a rigid transition component between the flexible forearm 30 and the flexible fingers 20, ensuring connection reliability and mechanical transmission stability. The roots of at least three flexible fingers 20 are fixed to the end of the rigid connecting base 10 away from the flexible forearm 30, and are distributed at a preset angle (e.g., uniform or non-uniform distribution) along the circumference of the rigid connecting base 10 to adapt to the envelope grasping requirements of target objects of different shapes.

[0027] The core design highlight of this embodiment lies in the internal structure of the soft finger 20: it contains multiple cell structures, which are rhomboid cells 21, and these rhomboid cells 21 are arranged in a non-uniform manner. By adjusting the cell density, size, and shape, differentiated mechanical responses in different areas of the soft finger 20 are achieved. An eccentric reference axis is pre-set inside the soft finger 20. This axis extends along the length of the finger and is biased towards the outer side of the rigid connecting base 10 (i.e., the side away from the direction of finger bending towards the palm, the back of the hand), serving as the reference for the arrangement of the rhomboid cells 21.

[0028] The rhomboid cell 21 extends radially outward from the reference axis along the soft finger 20. Its topological configuration is optimized: when the soft finger 20 bends towards the palm (i.e., away from the back of the hand where the reference axis is located), the rhomboid cell 21 can adapt to deformation, reduce bending resistance, and ensure stable and smooth bending action; when the finger is subjected to an external force in the direction away from the palm (i.e., towards the back of the hand where the reference axis is located), the rhomboid cell 21 can quickly lock and provide high bending stiffness, effectively limiting reverse buckling phenomenon and avoiding grasping failure due to reverse deformation during the grasping process, thus adapting to the usage requirements of complex underwater operating environments.

[0029] To facilitate understanding of the technical solution in this embodiment, the following provides further explanation of key terms: Rigid connecting base 10: Made of rigid materials (such as metal, hard plastic, composite materials), it serves as a transition component between the soft forearm 30 and the soft finger 20. It is fixed to the soft forearm 30 by means of bonding, bolting, or integral molding to ensure the stability of mechanical transmission and the reliability of connection.

[0030] Soft finger 20: The core execution component of the gripping device, it is integrally molded from elastic materials such as silicone and thermoplastic polyurethane (TPU), and has a specific internal structural design. It can bend and deform through the traction of the drive rope, thereby enveloping and clamping the target object.

[0031] Cellular structure: refers to the repetitive geometric units (which can be hollow or filled) formed inside the soft material. Its shape, size and arrangement directly determine the overall mechanical properties of the soft structure. The rhomboid cell 21 used in this embodiment is the key structure to realize the anti-reverse bending function of the soft finger 20.

[0032] Reference axis: A geometric reference line set inside the soft finger 20, which does not coincide with the geometric center axis of the finger, but is biased away from the side of the finger that bends towards the palm (i.e., the back of the hand side), and is used to locate the arrangement of the rhomboid cells 21 to ensure that the topological configuration of the cell structure meets the anti-reverse buckling design requirements.

[0033] Therefore, the soft manipulator structure provided in the embodiments of this application addresses the core technical pain points of existing underwater soft grasping devices, specifically including: soft fingers are prone to reverse flexion, which leads to grasping failure; the soft structure has a uniform mechanical response, making it difficult to achieve precise envelope grasping of the target object. To address the aforementioned technical issues, this embodiment achieves significant technical results through multi-dimensional optimization design: First, relying on the topological design of the eccentric reference axis (biased towards the back of the hand, away from the direction of finger bending towards the palm) and the non-uniformly arranged rhomboid cells 21 inside the soft finger 20, the reverse bending phenomenon of the finger can be effectively suppressed, significantly improving the stability and reliability of the grasping process and adapting to complex underwater operating conditions; Second, the non-uniform arrangement design of the rhomboid cells 21 enables different mechanical responses in different areas of the soft finger 20, and combined with the multi-finger collaborative arrangement method, it can accurately envelop target objects of different shapes and sizes, improving grasping adaptability; Third, the integrated structural design of the rhomboid cells 21 and the eccentric reference axis inside the soft finger 20 can fully utilize the elastic potential energy of the material itself to achieve reverse drive reset, saving the energy consumption and hardware cost required for reverse drive, effectively reducing the dependence on continuous high power consumption drive, and thus extending the service life of the device in underwater high-frequency operating scenarios.

[0034] For example, see Figure 3 The rhomboid cell 21 forms a porous structure on the sidewall of the soft finger 20, which is divided into at least two regions with different average bending stiffness in the circumferential direction of the soft finger 20; the at least two regions include a first region 20A and a second region 20B, the average bending stiffness of the first region 20A is less than the average bending stiffness of the second region 20B; when the soft finger 20 bends under the traction of the drive rope, the first region 20A corresponds to the inner side of the bend and the second region 20B corresponds to the outer side of the bend.

[0035] It is understood that the porous structure is not simply a surface perforation, but rather a continuation of the internal rhombic cell topology 21 on the outer wall, and its geometry and distribution directly affect local mechanical properties. For example, by adjusting the cell wall thickness, pore size, or arrangement density, the sidewalls can exhibit differentiated material filling rates, thus forming a visible porous morphology on a macroscopic scale. Based on this, the porous structure can be designed with circumferential stiffness partitioning. In actual manufacturing, this can be achieved by changing the size, wall thickness, arrangement density, or material properties of the cells in different regions. For example, larger, more open, or thinner cells can be used in the first region 20A to reduce its average bending stiffness; while in the second region 20B, smaller, denser, or thicker cells can be used to increase its stiffness. This stiffness difference is key to achieving directional bending: the first region 20A is flexible and easily deformable, while the second region 20B is rigid and tensile-resistant. This design ensures that the finger has good flexibility in the predetermined direction while maintaining sufficient support in the reverse direction.

[0036] When the drive rope pulls the fingers to bend towards the palm, the low-stiffness first region 20A is naturally located on the inner side of the bend (compression side), while the high-stiffness second region 20B is located on the outer side of the bend (tension side). This correspondence is predetermined during the design and manufacturing stages and is achieved by matching the drive direction with the stiffness distribution.

[0037] Therefore, this embodiment constructs a differentiated stiffness distribution in a porous structure, so that when the soft finger 20 is bent, the inner side is easy to compress and deform, and can compliantly wrap around the object; while the outer side can effectively resist stretching and reverse buckling, significantly improving its anti-interference ability and stability when grasping heavy objects or withstanding water flow impact, thereby overcoming the defect of traditional isotropic soft fingers 20 being prone to instability.

[0038] For example, see Figure 1 and Figure 3 A longitudinal rib 22 is provided at the center of the second region 20B. The longitudinal rib 22 extends along the length direction of the soft finger 20 and passes through the rhomboid cell 21 in that direction. The longitudinal rib 22 and the reference axis are located on the same plane.

[0039] The longitudinal rib 22 is a strip-shaped or rod-shaped reinforcing structure used to provide concentrated support and additional stiffness for the second region 20B. In a specific implementation, the longitudinal rib 22 can be integrally formed with the finger body, for example, by simultaneous manufacturing through 3D printing. The longitudinal rib 22 extends along its length, so that its supporting effect covers the entire effective working length of the finger, thereby providing a uniform reinforcement effect. It is worth noting that the longitudinal rib 22 penetrating the rhomboid cell 21 means that its structure radially divides the inner cavity of the cell. For example, the solid part of the longitudinal rib 22 passes through the rhomboid cell 21 and divides its inner cavity into two triangular chambers. This design maintains the topological continuity of the cell while forming a structural connection between the longitudinal rib 22 and the cell wall, enhancing the integrity and stiffness continuity of the overall structure and helping to prevent cell instability or collapse under stress. Furthermore, the longitudinal rib 22 is set to be coplanar with the reference axis. This configuration ensures that the support direction of the longitudinal rib 22 is consistent with the bending reference of the soft finger 20, thereby optimizing the force transmission path during bending and enabling the longitudinal rib 22 to effectively resist the reverse bending moment and suppress unexpected twisting or instability.

[0040] Through the above arrangement, the longitudinal rib 22 forms a continuous rigid support in the second region 20B. When the fingers bend towards the palm, the longitudinal rib 22 located on the outer side of the bend can effectively improve the tensile and buckling resistance of the second region 20B, thereby significantly enhancing the load stability and anti-interference ability of the overall structure while maintaining the inner flexibility.

[0041] For example, see Figures 1 to 5The number of soft fingers 20 is set to three, and they adopt an asymmetrical configuration of one short and two long fingers. Specifically, the two long soft fingers 20a are arranged symmetrically relative to the short soft fingers 20b. This layout simulates the grasping principle of a biological hand, adapting to objects of different sizes and shapes through differences in finger length, thereby improving the flexibility of grasping operations. In actual arrangement, the three soft fingers 20 can be distributed at equal angles of 120 degrees on the rigid connecting base 10, with the short finger and the two long fingers forming a symmetrical relationship; alternatively, depending on the specific grasping task, a non-equidistant angle distribution can be adopted, but the core configuration of one short and two long fingers with symmetry of the long fingers is always maintained.

[0042] The short, flexible finger 20b is not directly connected to the rigid connecting base 10, but rather transitions through a soft finger root 20c. This soft finger root 20c is essentially a built-in flexible structure that provides the short finger with additional degrees of freedom of movement, enabling it to independently pitch or yaw, thereby more actively adjusting its opposition posture. The soft finger root 20c can be a separate flexible module, connected by adhesive or mechanical means; a better approach is to incorporate it into a one-piece design, making it a natural extension of the base of the short, flexible finger 20b.

[0043] To achieve the desired flexibility, multiple rhomboid cells 21 are uniformly arranged within the finger root soft body 20c. These cell structures form internal cavities, effectively reducing the overall stiffness of this region and making it a flexible joint with controllable performance. Unlike the cells with gradient variations within the finger body, the uniform arrangement here aims to ensure that the finger root soft body 20c has a consistent and controllable flexible response in all directions. These cells can be integrally formed using 3D printing technology or formed using a soluble core mold casting method.

[0044] Specifically, these rhomboid cells 21 extend radially outward from the central axis of the finger root soft body 20c. This arrangement allows for a more uniform distribution of internal stress in the finger root soft body 20c during bending, while also enhancing its radial structural stability and effectively preventing irregular local collapse or unstable deformation under stress.

[0045] The short soft finger 20b and the finger root soft body 20c, which possesses the aforementioned characteristics, together constitute a functional unit—the soft thumb 20d. It integrates the grasping function of the short finger with the joint flexibility of the finger root soft body 20c, enabling the entire device to achieve a palm-to-palm grasping action similar to that of a human hand.

[0046] As a key functional finger of the gripper, the soft thumb 20d is designed to be shorter than the two long soft fingers 20a. This biomimetic length difference optimizes the envelope space formed when the thumb and long fingers work together, enabling it to adapt to a wider range of object sizes and facilitating operations in confined spaces.

[0047] Furthermore, both the long flexible finger 20a and the flexible thumb 20d adopt a tapered shape with a large diameter at the base and a small diameter at the tip. This design allows the finger base to have higher stiffness to effectively transmit driving force and resist reverse buckling; while the tip maintains good flexibility to better conform to the surface of the object and achieve a stable envelope.

[0048] In terms of manufacturing process, the long soft finger 20a, the soft thumb 20d, and their internal complex rhomboid cell structure 21 are all integrally formed from elastic materials using 3D printing technology. For example, thermoplastic polyurethane (TPU) and other materials can be used for fused deposition modeling (FDM). Integral molding ensures the integrity of the structure and the consistency of the materials, avoiding the risk of failure caused by connections, thereby significantly improving the reliability and durability of the entire gripping device.

[0049] Through the above design, this embodiment improves the performance of the grasping device. Specifically, the layout of one short and two long fingers, along with the introduction of a soft thumb 20d, achieves a palm-to-palm grasping mode similar to that of a human hand, enhancing adaptability. The uniformly and radially arranged rhomboid cells 21 within the soft finger root 20c provide a stable and controllable flexible joint for the thumb. The combination of the isotropic omnidirectional adjustment function of the proximal segment (i.e., the soft finger root 20c) and the anisotropic strong locking function of the distal segment (i.e., the short soft finger 20b) allows for both flexible approach over a large area and precise locking operation in a small area when facing targets with uncertain spatial positions and varying shapes. The conical shape design and one-piece manufacturing method ensure flexibility at the tip while enhancing the structural strength and overall reliability of the root, enabling it to stably and efficiently grasp diverse objects in complex underwater environments.

[0050] For example, see Figure 1 and Figure 6 The soft robotic arm structure also includes a soft forearm 30, one end of which is a base connection end 31 for connecting to an external mechanism; the other end of the soft forearm 30 is connected to the end of the rigid connecting base 10 away from the soft finger 20.

[0051] Understandably, the flexible forearm 30 is made of flexible material, possessing excellent flexibility and deformation capability. Its core function is to connect to external mechanisms and provide basic support for the entire gripping device. It can be formed through processes such as molding and additive manufacturing, and its interior can be designed as hollow or specifically filled structures, balancing flexibility and support strength. The reasonable combination of the flexible forearm 30 and the rigid connecting base 10 balances the overall flexibility of the device and the stability of mechanical transmission, enabling stable docking with external working platforms and effectively expanding the application scenarios of the device.

[0052] For example, see Figure 6The soft forearm 30 is designed with a hollow conical structure. The base connection end 31, which connects to the external mechanism, has a larger diameter, while the end near the rigid connecting base 10 has a smaller diameter. This tapered geometry results in a gradual decrease in the forearm's stiffness from the base to the end. The base connection end 31 thus possesses higher load-bearing and impact resistance to adapt to loads and external disturbances; the end is more flexible, facilitating flexible adjustment of the grasper's spatial position underwater.

[0053] To achieve both lightweight design and high flexibility, the sidewalls of the soft forearm 30 are designed as a mesh structure 32 rather than a solid structure. This mesh structure 32 is mainly composed of diamond-shaped holes. The diamond-shaped holes facilitate greater structural deformation, achieving lightweight design while maintaining overall flexibility.

[0054] To further enhance axial stiffness and bending resistance, and to prevent unexpected lateral bending or twisting during driving or under load, several longitudinal reinforcing ribs 33 are provided along the length of the sidewall of the flexible forearm 30. These reinforcing ribs 33 are evenly spaced in the circumferential direction of the flexible forearm 30, thereby ensuring that the forearm has an isotropic mechanical response when bending in all directions, simplifying motion control.

[0055] From a manufacturing perspective, the entire soft forearm 30, including its conical shell, mesh sidewalls, and longitudinal reinforcing ribs 33, is integrally molded from an elastic material (such as TPU) using 3D printing technology. This integral molding process eliminates assembly interfaces, ensuring the structural integrity and reliability while simplifying the production process.

[0056] Through the above design, the soft forearm 30 in this embodiment achieves a balance between stiffness gradient distribution and omnidirectional compliant bending capability while maintaining lightweight construction. Its structure not only effectively supports the end effector and resists underwater impacts, but also enables precise and stable spatial movement through its flexible deformation, providing a reliable and flexible motion base for the entire grasping device.

[0057] For example, see Figures 2 to 6The flexible forearm 30, rigid connecting base 10, long flexible finger 20a, short flexible finger 20b, and finger root flexible 20c are all provided with channels 40 for the drive rope to pass through. The channels 40 are made of plastic tubes. There are at least three channels 40 for driving the flexible forearm 30 to bend, evenly distributed around the circumference of the flexible forearm 30; there are two channels 40 for driving the long flexible finger 20a to bend, symmetrically arranged on both sides of the first region 20A of the long flexible finger 20a; there are also two channels 40 for driving the short flexible finger 20b to bend, symmetrically distributed on both sides of the first region 20A of the short flexible finger 20b. In other embodiments, there may be one channel 40, located at the center of the first region 20A of the short flexible finger 20b; there are at least three channels 40 for driving the finger root flexible 20c to bend, spaced apart around the circumference of the finger root flexible 20c on the side facing the long flexible finger 20a.

[0058] The soft forearm 30 near the rigid connecting base 10, the soft finger root 20c near the short soft finger 20b, the end of the long soft finger 20a, and the end of the short soft finger 20b are all provided with anchoring holes 50 that match the number of their own channels 40, for fixing the drive rope.

[0059] The flexible forearm 30 and the rigid connecting base 10, the rigid connecting base 10 and the long flexible finger 20a and the finger root flexible 20c respectively, and the finger root flexible 20c and the short flexible finger 20b are all connected by end face flanges.

[0060] To address the technical pain points of increased friction in the drive rope, insufficient drive efficiency, and unstable component connections, this embodiment focuses on optimizing the drive rope threading channel 40 and the component connection structure, as detailed below: The core function of the drive rope channel 40 is to provide a smooth, low-friction guiding path for the drive rope, ensuring that the driving force is efficiently and accurately transmitted to each soft component. Based on this requirement, plastic tubes are preferred for the channel 40, specifically polytetrafluoroethylene (PTFE), polyethylene (PE), or polyvinyl chloride (PVC) tubes. These materials have a low coefficient of friction, which can significantly reduce the resistance during the movement of the drive rope, thereby reducing drive energy consumption and extending the service life of the drive rope.

[0061] Based on the driving characteristics of each soft component, the number and arrangement of channels 40 are specifically designed: the soft arm 30 needs to achieve stable movement in three-dimensional space underwater, so it has no less than 3 driving channels 40, which are evenly arranged in the circumference. For example, 3 channels 40 are distributed at 120° intervals, and 4 channels 40 are distributed at 90° intervals. This can avoid local stress concentration and improve the stability and control accuracy of the arm bending.

[0062] Both the long and short soft fingers 20b have two drive channels 40, which are symmetrically arranged on both sides of their respective first regions 20A (low-stiffness regions). This design can precisely guide the fingers to bend along a preset low-stiffness direction, making full use of the non-uniform stiffness characteristics of the soft fingers 20. While achieving flexible envelopment of the target object, it effectively restricts reverse buckling and ensures grasping stability.

[0063] The finger root soft body 20c has no fewer than three driving channels 40, which are arranged circumferentially at intervals on the side facing the long soft finger 20a. Typically, three or four channels 40 can be provided, which can flexibly adjust the palmar angle of the short soft finger 20b (which together with the finger root soft body 20c constitutes the soft thumb 20d) relative to the long soft finger 20a, adapt to target objects of different shapes, and optimize the grasping envelope effect.

[0064] The reliability of the connection between the drive rope and the software components directly affects the control accuracy. Therefore, anchoring holes 50 are set at each key location, which are matched with the number of channels 40. The drive rope can be anchored in the anchoring holes 50 by knotting, pressing sleeves or fixing beads, etc., to effectively prevent the drive rope from slipping under force and ensure efficient transmission of driving force and accurate control response.

[0065] In terms of component connection, all connection nodes adopt end face flange connection, which can be connected by bolts and nuts, quick release clamps, or reinforced with adhesive. This provides a firm and reliable mechanical fixation, reduces the risk of loosening between components, enhances the structural integrity and durability of the entire gripping device, and is suitable for impact and water flow disturbance conditions in complex underwater environments.

[0066] Through the above design scheme, this embodiment can effectively solve the core pain points of the existing technology and greatly improve the accuracy, durability and operational stability of the underwater grasping device: the plastic tube channel 40 uses low friction characteristics to reduce the running resistance of the drive rope, reduce the energy consumption of the drive motor, alleviate the wear of the drive rope and the channel 40, and extend the service life of the device; the optimization of the number and position of the channel 40, combined with the structure of the soft components themselves (such as the conical hollow structure of the soft forearm 30, the mesh sidewall, the non-uniform arrangement of the rhomboid cells 21 of the soft fingers, the eccentric reference axis and the low bending stiffness design of the first region 20A), realizes the precise driving and stable operation of each component.

[0067] The matching design of the anchoring hole 50 and the channel 40 ensures the reliability of the drive rope connection and guarantees the accurate execution of control commands. The end flange connection enhances the connection stability of each component, preventing loosening of components due to impact and vibration during underwater operations, and further improving the overall rigidity and operational reliability of the device. Thus, this embodiment, through the refined design of the drive rope channel 40 and the connection method of the components, achieves improved drive efficiency, mitigates material fatigue, and reduces the risk of reverse buckling, ultimately ensuring high-precision, high-efficiency, and long-life operation of the underwater grasping device in complex underwater environments.

[0068] The above description is merely an embodiment of the present invention and is not intended to limit the scope of protection of the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A soft robotic arm structure, characterized in that, include: Rigid connecting base; as well as At least three soft fingers are fixedly connected at their base to one end of the rigid connecting base away from the soft forearm, and the soft fingers are distributed at a predetermined angle along the circumference of the rigid connecting base. The soft finger contains multiple cell structures, which are rhomboid cells, and these rhomboid cells are not uniformly distributed inside the soft finger. The soft finger has an eccentrically positioned reference axis inside, which extends along the length of the finger and is located near the inner side of the rigid connecting base. The rhomboid cells are radially distributed along the radial direction of the soft finger, with the reference axis as the reference, and extend from the reference axis toward the outer periphery of the soft finger. The topological configuration of the rhomboid cell is configured such that the finger can be stably bent in the direction near the palm, while bending is restricted in the direction far from the palm.

2. The soft robotic arm structure according to claim 1, characterized in that, The rhomboid cells form a porous structure on the sidewall of the soft finger, which is divided into at least two regions with different average bending stiffness in the circumferential direction of the soft finger; the at least two regions include a first region and a second region, wherein the average bending stiffness of the first region is less than that of the second region; the first region is located on the side closer to the palm, and the second region is located on the side farther from the palm.

3. The soft robotic arm structure according to claim 2, characterized in that, A longitudinal rib is provided at the center of the second region. The longitudinal rib extends along the length of the soft finger and passes through the rhomboid cell in that direction. The longitudinal rib is located on the same plane as the reference axis.

4. The soft robotic arm structure according to claim 2, characterized in that, The soft fingers consist of three fingers, arranged in a configuration of one short and two long fingers, with the two long fingers symmetrically arranged relative to the short fingers. A finger root soft element connects the short soft finger to the rigid connecting base. The finger root soft element contains multiple rhomboid cell structures, evenly distributed within it. These rhomboid cells are radially distributed along the central axis of the finger root soft element, extending from its central axis towards its outer periphery. The short soft finger and the finger root soft element together form a soft thumb. The long soft finger, the soft thumb, and the rhomboid cells within both are integrally printed from an elastic material.

5. The soft robotic arm structure according to claim 4, characterized in that, The length of the soft thumb is less than the length of the long soft finger; both the long soft finger and the soft thumb are tapered with a base diameter greater than a tip diameter.

6. The soft robotic arm structure according to claim 4, characterized in that, It also includes a soft forearm, one end of which is a base connection end for connecting to an external mechanism; the other end of the soft forearm is connected to the end of the rigid connecting base away from the soft finger.

7. The soft robotic arm structure according to claim 6, characterized in that, The flexible forearm has a hollow, conical structure, with the diameter of its base connection end being larger than the diameter of the end closest to the rigid connection base. The sidewall of the flexible forearm has a mesh structure, and the sidewall of the flexible forearm is provided with multiple reinforcing ribs extending along the length of the flexible forearm. The multiple reinforcing ribs are evenly spaced along the circumference of the flexible forearm. The flexible forearm and the reinforcing ribs are integrally printed from an elastic material.

8. The soft robotic arm structure according to claim 7, characterized in that, The flexible forearm, the rigid connecting base, the long flexible finger, the short flexible finger, and the finger root soft body are all provided with channels through which drive ropes can pass. These channels are made of plastic tubes. Specifically, there are at least three channels for driving the bending of the flexible forearm, evenly distributed along the circumference of the flexible forearm; two channels for driving the bending of the long flexible finger, symmetrically arranged on both sides of the first region of the long flexible finger; two channels for driving the bending of the short flexible finger, symmetrically arranged on both sides of the first region of the short flexible finger; and at least three channels for driving the bending of the finger root soft body, spaced apart along the circumference of the finger root soft body on the side of the finger root soft body facing the long flexible finger.

9. The soft robotic arm structure according to claim 8, characterized in that, The soft forearm near the rigid connecting base, the soft root near the short soft finger, the end of the long soft finger, and the end of the short soft finger are all provided with anchoring holes adapted to the number of their own channels. The anchoring holes are used to connect the drive rope.

10. The soft robotic arm structure according to claim 7, characterized in that, The flexible forearm is connected to the rigid connecting base, the rigid connecting base is connected to the long flexible finger, the rigid connecting base is connected to the finger root flexible component, and the finger root flexible component is connected to the short flexible finger via end face flanges.

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