A variable stiffness wrist-digits composite soft actuator

Abstract

The utility model belongs to the field of robot technology provides a kind of wrist-claw composite soft actuator of variable stiffness, comprising: woven type gripper, woven type mechanical arm and connecting piece, wherein: woven type gripper is made of multiple groups of gripping dynamic muscle tendon and the winding dynamic muscle tendon that is circumferentially wound in the outer periphery of gripping dynamic muscle tendon;Woven type mechanical arm is made of multiple parallel and interval arrangement longitudinal dynamic muscle tendon and the spiral dynamic muscle tendon that is woven in the outer periphery of longitudinal dynamic muscle tendon.Compared with prior art, the utility model has the advantages that by the weaving technology of pneumatic artificial muscle, the integrated composite structure design of wrist (mechanical arm) and claw part (gripper) is realized, driving, bearing structure and stiffness adjusting mechanism are deeply fused in single flexible woven body, without introducing traditional rigid element, active, wide-range variable stiffness control can be realized, and weaving forming process simplifies manufacturing process, reduces cost, improves the integrity and reliability of structure simultaneously.

Description

Technical Field

[0001] This utility model belongs to the field of robotics technology, specifically relating to a variable stiffness wrist-claw composite soft actuator. Background Technology

[0002] Soft robots, due to their high compliance, environmental adaptability, and inherent safety, demonstrate significant advantages in interacting with non-cooperative targets or in human-robot collaborative tasks. Among them, soft grippers and soft robotic arms, as typical execution units, have been applied in several cutting-edge fields. However, traditional soft actuators are generally made of low-modulus elastic materials (such as silicone and latex), which makes it difficult to maintain compliance while ensuring high load capacity, creating an inherent contradiction between "compliance, stiffness, and load."

[0003] To improve load performance, existing technologies attempt to introduce variable stiffness mechanisms such as particle blockage, interlayer friction, phase change materials, or rigid skeletons. However, these methods often rely on additional rigid components or complex structures, which not only weakens the intrinsic compliance of soft robots but also increases system weight, assembly difficulty, and failure risk. For example, Chinese patent CN106584507A discloses a fully flexible pneumatic robotic arm that mimics octopus tentacles. Although it achieves structural and actuation integration, it lacks active stiffness variation capability. Patent CN110733032A proposes an airbag-driven robotic arm, which reduces airtightness requirements but cannot dynamically adjust between compliance and stiffness, limiting its applicability in precision operations. Therefore, using weaving technology to construct a composite soft actuator that combines wrist movement and claw grasping functions with active stiffness variation capability remains a technological gap. Utility Model Content

[0004] The purpose of this invention is to address the aforementioned problems in the existing technology by proposing a variable stiffness wrist-claw composite soft actuator that features a simple structure, good stability, and the ability to achieve active, wide-range variable stiffness control.

[0005] The objective of this utility model can be achieved by addressing the following technical problem: a variable stiffness wrist-claw composite soft actuator is proposed, comprising a woven gripper, a woven robotic arm, and a connector, wherein:

[0006] The woven gripper consists of multiple sets of gripping tendons and a wrapping tendon that is circumferentially wrapped around the outer periphery of the gripping tendons;

[0007] The woven robotic arm consists of multiple parallel and spaced longitudinal kinetic tendons and spiral kinetic tendons woven around the periphery of the longitudinal kinetic tendons. The gripping stiffness and the overall stiffness of the robotic arm can be changed by adjusting the internal air pressure of the gripping kinetic tendon and the spiral kinetic tendon, respectively.

[0008] The woven gripper and the woven robotic arm are connected to an external pneumatic system via the connector;

[0009] When the actuator is working, the grasping tendon can open or close due to the change in air pressure inside the wrapped tendon; and when there is an air pressure difference between the multiple longitudinal tendons, the woven robotic arm can be bent or extended.

[0010] In the aforementioned variable stiffness wrist-claw composite soft actuator, the helical kinetic tendon is helically woven around the periphery of the longitudinal kinetic tendon.

[0011] In the aforementioned variable stiffness wrist-claw composite soft actuator, the grasping tendon, longitudinal tendon, winding tendon, and spiral tendon are all composed of a highly elastic latex tube as the inner cavity and an outer woven mesh covering.

[0012] In the aforementioned variable stiffness wrist-claw composite soft actuator, the coiling tendon is spirally wound around the periphery of the grasping tendon.

[0013] In the aforementioned variable stiffness wrist-claw composite soft actuator, the connecting member includes a base and a connecting disk, wherein,

[0014] The base has a plurality of connecting tube heads arranged in a ring at equal intervals on the side wall away from the connecting plate, and fixing tubes are formed on the opposite side walls of the base and the connecting plate. The latex tube is sleeved on the connecting tube head and the fixing tube to tie the longitudinal kinetic tendon and the grasping kinetic tendon together tightly on the base, and to tie the end of the longitudinal kinetic tendon away from the base to the connecting plate.

[0015] In the aforementioned variable stiffness wrist-claw composite soft actuator, the base and the connecting disc have an initial end and an end respectively formed on their opposite sidewalls, and the two ends of the helical tendon are respectively connected to the initial end and the end.

[0016] In the aforementioned variable stiffness wrist-claw composite soft actuator, a first connecting joint is formed on the side wall of the base, and a second connecting joint and a third connecting joint are formed on the side wall of the connecting plate opposite to the base. The first connecting joint is used to deliver gas to the grasping tendon, the second connecting joint is connected to the longitudinal tendon, and the third connecting joint is connected to the helical tendon.

[0017] In the aforementioned variable stiffness wrist-claw composite soft actuator, the bending angle range of the multiple longitudinal tendons when there is a pressure difference is 0°-50°.

[0018] In the aforementioned variable stiffness wrist-claw composite soft actuator, each of the gripping tendons has a gripping part and a connecting part that are interconnected. The connecting part is connected to the connecting tube head, and the gripping part and the connecting part are arranged at an angle and in a U-shape.

[0019] In the aforementioned variable stiffness wrist-claw composite soft actuator, the ends of both the second and third connecting joints are formed with extension rings, which can cooperate with the sealing ring to maintain airtightness with the external air circuit system.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] (1) The variable stiffness wrist-claw composite soft actuator of this utility model realizes the integrated composite structure design of wrist (mechanical arm) and claw (gripper) through the weaving technology of pneumatic artificial muscle. The drive, load-bearing structure and stiffness adjustment mechanism are deeply integrated into a single flexible weaving body. Active and wide-range variable stiffness control can be achieved without the introduction of traditional rigid components. Moreover, the weaving molding process simplifies the manufacturing process, reduces costs, and improves the integrity and reliability of the structure.

[0022] (2) By spirally wrapping the spiral kinetic tendon around the periphery of the longitudinal kinetic tendon, an effective radial constraint force can be generated during inflation, maximizing the "weaving blocking effect" and thus significantly improving the overall stiffness of the robotic arm without excessively sacrificing flexibility.

[0023] (3) The structure of using high-elasticity latex tubing as the inner cavity and high-strength braided mesh as the outer covering serves as the basic unit for various dynamic tendons. It has excellent airtightness and large deformation capacity, providing a reliable and stable driving and bearing foundation for the actuator. At the same time, it is easy to integrate and form, reducing manufacturing complexity. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the overall structure of this application;

[0025] Figure 2 This is a schematic diagram of the longitudinal muscular tendon;

[0026] Figure 3 This is a schematic diagram of the spiral agonist tendon;

[0027] Figure 4 This is a structural diagram of the base;

[0028] Figure 5 yes Figure 4 Rear view;

[0029] Figure 6 This is a structural diagram of the connecting plate;

[0030] Figure 7 yes Figure 6 Rear view.

[0031] In the diagram, 1 is a woven gripper; 10 is a gripping tendon; 100 is a gripping part; 101 is a connecting part; 2 is a woven robotic arm; 20 is a longitudinal tendon; 21 is a helical tendon; 30 is a latex tube; 31 is a woven mesh; 4 is a connector; 40 is a base; 400 is a connecting tube end; 401 is the initial end; 402 is the first connecting joint; 41 is a connecting plate; 410 is the final end; 411 is the second connecting joint; 412 is the third connecting joint; 420 is a fixing tube; and 421 is an extension ring. Detailed Implementation

[0032] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings to further illustrate the technical solutions of the present invention. However, the present invention is not limited to these embodiments.

[0033] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0034] like Figures 1 to 7 As shown, this utility model discloses a variable stiffness wrist-claw composite soft actuator, which includes a woven gripper 1, a woven robotic arm 2, and a connector 4.

[0035] The woven gripper 1 consists of multiple gripping tendons 10 and a coiled tendon wrapped around the outer periphery of the gripping tendons 10. The woven robotic arm 2 consists of multiple parallel and spaced longitudinal tendons 20 and a spiral tendon 21 woven around the outer periphery of the longitudinal tendons 20. The gripping stiffness and the overall stiffness of the robotic arm can be changed by adjusting the internal air pressure of the gripping tendons 10 and the spiral tendons 21 respectively. The woven gripper 1 and the woven robotic arm 2 are connected to the external air system through the connector 4. When the actuator is working, the gripping tendons 10 can open or close due to the change in the internal air pressure of the coiled tendons. The woven robotic arm 2 can bend or extend when there is an air pressure difference between the multiple longitudinal tendons 20.

[0036] Specifically, such as Figures 1 to 7As shown, the braided gripper 1 in this embodiment mainly consists of five sets of U-shaped longitudinal tendons 20 and circumferentially wrapped tendons. When compressed gas (the pressure range is usually 0–0.25 MPa) is injected into the wrapped tendons, they expand radially and contract axially, applying a circumferential constraint force to the internal gripping tendons 10. This forces the multiple sets of U-shaped gripping tendons 10 to move towards the center, thereby driving the braided gripper 1 to close and complete the gripping of the target object. When the wrapped tendons are deflated, they return to their initial length. Under the action of the material's elastic restoring force, the gripper automatically opens, realizing the release action. During or after the gripping process, a certain pressure (e.g., 0–0.2 MPa) is injected into the gripping tendons 10, causing them to expand internally and limiting the local deformation ability of the gripping structure, thereby actively improving the overall structural stiffness and gripping stability of the gripper. The woven robotic arm 2 in this embodiment includes at least three (three are used as an example in this embodiment) parallel and spaced longitudinal kinetic tendons 20 (the coiled kinetic tendons in this embodiment have the same structure as the spiral kinetic tendons 21, which will not be described again here). By adjusting the air pressure value in the three longitudinal kinetic tendons 20, the robotic arm is driven to bend towards the low-pressure side. If all longitudinal kinetic tendons 20 are inflated / deflated simultaneously, the overall extension and contraction movement is realized, thereby realizing continuous bending, extension and contraction and other multi-degree-of-freedom flexible movements in two-dimensional or three-dimensional space, simulating the dexterous operation ability of a biological wrist. During the robotic arm's task execution, air pressure is injected into the spiral kinetic tendons 21, causing them to expand along the spiral path and tightly wrap around the longitudinal kinetic tendons 20. After being pressurized, this structure generates radial constraint on the longitudinal tendons, effectively inhibiting the bending or stretching deformation of the longitudinal tendons under external force, thereby significantly improving the tensile stiffness, bending stiffness and resistance to external disturbances of the robotic arm. Therefore, the actuator in this embodiment integrates the woven gripper 1 and the woven robotic arm 2 into one unit, and adopts a coordinated pneumatic pressure control mechanism of gripping tendon 10 / winding tendon and longitudinal tendon 20 / spiral tendon 21 respectively, to achieve decoupled control of gripping action and wrist movement; at the same time, the gripper can be driven to open and close by adjusting the air pressure of the winding tendon, and the robotic arm can be bent or extended by adjusting the air pressure difference of the longitudinal tendon 20. The structure is highly integrated and has no rigid joints, which significantly improves the compliance, environmental adaptability and control flexibility of the actuator, and has the ability to actively change stiffness, thus solving the core problem of traditional soft actuators being "flexible but not strong".

[0037] The grasping tendon 10, longitudinal tendon 20, winding tendon, and spiral tendon 21 are all composed of a highly elastic latex tube 30 as the inner cavity and an outer woven mesh 31 covering it.

[0038] like Figure 2As shown, this embodiment uses a high-elasticity latex tube 30 as the core, covered by a high-strength braided mesh 31. The high-elasticity latex tube 30 ensures good sealing and resilience, while the high-strength braided mesh 31 effectively converts internal pressure into axial contractile force. A single tendon can generate tens of Newtons of tension. Combined with multiple tendons in parallel, this gives the actuator excellent load-bearing capacity. Therefore, when compressed air is introduced into the inner cavity of the latex tube 30 of any tendon, the latex tube 30 expands radially under the internal air pressure. Because the outer braided mesh 31 has a fixed braiding angle and its fiber length is essentially imextensible, the radial expansion forces the braiding angle to decrease, thereby causing the tendon to shorten axially and generate contractile force. The latex-braided composite structure has good fatigue resistance and can withstand tens of thousands of inflation and deflation cycles. It achieves a high degree of integration of driving, load-bearing, and stiffness adjustment functions, not only improving the overall performance of the actuator but also providing a reliable technical path for soft robots to move towards practical application and engineering.

[0039] Preferably, in this embodiment, the spiral kinetic tendon 21 is spirally woven around the longitudinal kinetic tendon 20, and the weaving angle is preferably 30°-50° to ensure that an effective radial constraint force is generated during inflation, thereby significantly improving the overall rigidity of the robotic arm without excessively sacrificing flexibility, and avoiding excessive rigidity due to too small an angle, thus losing flexibility.

[0040] More preferably, in this embodiment, the spiral tendon is spirally wound around the periphery of the grasping tendon 10, and the braiding angle is preferably in the range of 45°-60°, so that it can be efficiently converted into the closing force of the grasping fingers when inflated and contracted, and at the same time, the latex tube 30 rebounds to achieve a rapid opening and release action when deflated; this angle range ensures high efficiency and high repeatability of the grasping action, and enhances the overall rigidity of the grasping structure through radial compression in the grasping state to prevent slippage, which is particularly suitable for grasping irregular or easily deformable objects.

[0041] The connector 4 includes a base 40 and a connecting plate 41. The side wall of the base 40 away from the connecting plate 41 has a plurality of connecting tube heads 400 distributed in a ring at equal intervals. Fixing tubes 420 are formed on the opposite side walls of the base 40 and the connecting plate 41. The latex tube 30 is sleeved on the connecting tube heads 400 and the fixing tubes 420 to tie the longitudinal kinetic tendon 20 and the grasping kinetic tendon 10 together on the base 40, and to tie the end of the longitudinal kinetic tendon 20 away from the base 40 to the connecting plate 41.

[0042] like Figure 1 , Figures 4 to 7As shown, in this embodiment, the braided gripper 1 and the braided robotic arm 2 are integrated and connected via a connecting plate 41 made of 3D printed resin material. The overall structure is connected to the external air supply system via the base 40. The tension of the dynamic tendons between the base 40 and the connecting plate 41 helps to preload the flexible structure, reduce initial relaxation, and improve response speed and motion accuracy. The base 40 and the connecting plate 41 integrate the dual functions of mechanical fixation and air interface. The overall structure is compact, and the number of connecting tube heads 400 can be flexibly increased or decreased according to the actuator's degrees of freedom, which facilitates the development of products of different specifications (such as 4-finger grippers, 6-degree-of-freedom wrists, etc.). In addition, it is precisely because of the double-end fixing structure of the base 40 and the connecting plate 41, combined with the connecting tube head 400 and the fixing tube 420 to tighten the latex tube 30, that reliable anchoring and air sealing of all dynamic tendons at both ends are achieved. This structure avoids the problems of easy leakage and easy detachment of traditional bonding or clamping methods, improves the long-term working stability and assembly consistency of the actuator, and provides a standardized interface for subsequent air integration.

[0043] The base 40 and the connecting plate 41 have an initial end 401 and an end 410 respectively on their opposite sidewalls, and the two ends of the spiral kinetic tendon 21 are connected to the initial end 401 and the end 410 respectively.

[0044] like Figure 1 As shown, during the manufacturing process, a high-elasticity latex tube 30 is inserted into a high-strength braided mesh 31 to form a helical tendon 21. Then, starting from the base 40, it is spirally wound along the outer surface of three parallel longitudinal tendons 20 with a constant pitch. Before this, the proximal end of the helical tendon 21 is pre-connected to the initial end 401, providing a starting reference for subsequent spiral winding, until the helical tendon 21 extends to the position of the connecting plate 41. After winding, the distal end of the helical tendon 21 is inserted and tightened to the end end 410 of the connecting plate 41, ensuring that it is reliably constrained in both the axial and circumferential directions. The two ends of the helical tendon 21 are fixed to the initial end 401 of the base 40 and the end end 410 of the connecting plate 41, respectively, to ensure that a helical constraint force is applied evenly along the entire length of the robotic arm when it is inflated, avoiding local stress concentration or slippage, thereby achieving uniform reinforcement of stiffness along the axial direction and improving the dimensional stability and bending resistance of the robotic arm under load.

[0045] A first connecting joint 402 is formed on the side wall of the base 40, and a second connecting joint 411 and a third connecting joint 412 are formed on the side wall of the connecting plate 41 away from the base 40. The first connecting joint 402 is used to deliver gas to the grasping tendon 10, the second connecting joint 411 is connected to the longitudinal tendon 20, and the third connecting joint 412 is connected to the helical tendon 21.

[0046] This embodiment provides three types of tendons with completely independent air passages by setting a first connecting connector 402 on the base 40 and setting a second and third connecting connector 412 on the connecting plate 41. The air pressure can be adjusted separately without interfering with each other, supporting independent and precise control of each tendon. This provides a hardware foundation for complex tasks (such as bending, changing stiffness, and grasping simultaneously), while simplifying the pipeline layout of the external pneumatic control system and improving system integration and reliability.

[0047] Preferably, in this embodiment, the bending angle range of the multiple longitudinal moving tendons 20 when there is an air pressure difference is 0°-50°. This range ensures that the robotic arm has sufficient motion flexibility to adapt to the multi-posture operation requirements in unstructured environments, while avoiding excessive bending that could lead to internal tendon stretching failure or buckling instability of the outer braided structure, thus ensuring that the actuator achieves high-precision trajectory tracking within a safe working range.

[0048] Each grasping tendon 10 has a grasping part 100 and a connecting part 101 that are interconnected. The connecting part 101 is connected to the connecting tube head 400. The grasping part 100 and the connecting part 101 are arranged at an angle and in a U-shape.

[0049] like Figure 1 As shown, each grasping tendon 10 is designed with a U-shaped grasping part 100 and a connecting part 101, which are set at an angle. This allows the grasping part 100 to naturally form an envelope-like grasping shape under the drive of the wrapped tendon, effectively conforming to targets of different shapes. The U-shaped arrangement, combined with the angled design of the grasping part 100 and the connecting part 101, allows the grasping fingers to naturally form a converging arc trajectory when closed. This enables adaptive envelope grasping of spheres, cylinders, and irregular objects without complex control, improving the success rate and stability of the grasping.

[0050] Both the second connecting joint 411 and the third connecting joint 412 have an extension ring 421 at their ends. The extension ring 421 can work with the sealing ring to maintain airtightness with the external air circuit system, significantly improving the airtightness and vibration resistance at the connection with the external air circuit system. This structure can maintain a long-term seal under frequent insertion and removal or dynamic operating conditions, preventing air leakage from causing control failure. Preferably, the connecting joints in this embodiment can all adopt standard quick-connect pneumatic interfaces (such as φ4 or φ6mm). The internal flow channel is precisely designed to avoid sharp bends or abrupt changes in cross-section, ensuring smooth gas flow and rapid response. The latex tube 30 and the joint are sealed by clamps or heat shrink seals. Combined with the guide hole inside the base 40 / connecting plate 41 and the fixing tube 420, it effectively prevents detachment or leakage under high pressure.

[0051] The working principle of this utility model of a variable stiffness wrist-claw composite soft actuator is as follows:

[0052] During manufacturing, a high-elasticity latex tube 30 is first inserted into a specially woven mesh 31 to prepare various types of moving tendons. Then, five grasping moving tendons 10 are arranged in a U-shaped path on a special weaving mold, and wrapped with a circumferential weaving method to form the main body of the woven gripper 1. For the robotic arm, three longitudinal moving tendons 20 are arranged in parallel, and a spiral moving tendon 21 is wrapped around the outside at a set weaving angle. Finally, the woven gripper and the robotic arm are assembled through a connecting plate 41. A quick-connect pneumatic connector is used to connect the pneumatic circuits of each moving tendon to ensure airtightness. The entire structure is then installed on the base 40 to complete the integrated assembly of the actuator.

[0053] When the actuator is working, it inflates the coiled kinetic tendon (pressure range 0–0.25 MPa), causing it to expand radially and contract axially (the principle is the same as described above, and will not be elaborated here), driving the gripper to close and achieve the gripping action. Conversely, deflating the tendon achieves the releasing action. By adjusting the internal air pressure of the coiled kinetic tendon (0–0.2 MPa), the rigidity of the gripper structure can be actively enhanced. Experiments show that its gripping force can be increased by up to 81.25 N, significantly improving the gripping stability of objects of different shapes and sizes. The woven robotic arm 2 achieves multi-degree-of-freedom bending and stretching movements by differentially controlling the air pressure of the three longitudinal muscles (referring to the difference in air pressure between the three longitudinal kinetic tendons 20). By adjusting the air pressure in the helical kinetic tendon 21, the wrist rigidity can be further enhanced, increasing its tensile strength by up to 120% and its resistance to external interference by 4.77 times, and the rigidity adjustment process hardly affects its motion accuracy.

[0054] It should be noted that the control system in this embodiment uses multiple electro-proportional valves (such as SMC ITV1030-212N) to independently control the air pressure of each group of moving tendons. The control system is uniformly scheduled by a microcontroller or programmable logic controller to achieve coordinated operation of gripping, motion and stiffness adjustment. Users can set the target posture, gripping force and stiffness mode of the actuator through host computer software or external commands to achieve flexible and precise task control.

[0055] Therefore, this actuator possesses multi-degree-of-freedom motion capabilities, actively controllable stiffness adjustment, and excellent compliance adaptability. It can grasp objects of various shapes, such as sheets, cylinders, and spheres, making it suitable for target manipulation in unstructured environments, human-machine collaboration, disaster relief, space exploration, and medical surgery. Its integrated braided structure avoids complex processes such as bonding and stitching, reducing potential failure points and achieving a high degree of integration between structure, drive, and stiffness. It maintains high compliance while possessing high load capacity and high reliability.

[0056] It should be noted that in this invention, the use of terms such as "first," "second," and "a" is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified. The terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two elements or the interaction between two elements, unless otherwise explicitly specified. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0057] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0058] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A variable stiffness wrist-claw composite soft actuator, characterized in that, The actuator includes a woven gripper, a woven robotic arm, and a connector, wherein: The woven gripper consists of multiple sets of gripping tendons and a wrapping tendon that is circumferentially wrapped around the outer periphery of the gripping tendons; The woven robotic arm consists of multiple parallel and spaced longitudinal kinetic tendons and spiral kinetic tendons woven around the periphery of the longitudinal kinetic tendons. The gripping stiffness and the overall stiffness of the robotic arm can be changed by adjusting the internal air pressure of the gripping kinetic tendon and the spiral kinetic tendon, respectively. The woven gripper and the woven robotic arm are connected to an external pneumatic system via the connector; When the actuator is working, the grasping tendon can open or close due to the change in air pressure inside the wrapped tendon; and when there is an air pressure difference between the multiple longitudinal tendons, the woven robotic arm can be bent or extended.

2. The variable stiffness wrist-claw composite soft actuator according to claim 1, characterized in that, The spiral kinetic tendon is spirally woven around the periphery of the longitudinal kinetic tendon.

3. The variable stiffness wrist-claw composite soft actuator according to claim 1, characterized in that, The grasping tendon, longitudinal tendon, winding tendon, and spiral tendon are all composed of a highly elastic latex tube as the inner cavity and an outer woven mesh covering.

4. A variable stiffness wrist-claw composite soft actuator according to claim 2, characterized in that, The coiled kinetic tendon is spirally wrapped around the periphery of the grasping kinetic tendon.

5. A variable stiffness wrist-claw composite soft actuator according to claim 3, characterized in that, The connector includes a base and a connecting plate, wherein... The base has a plurality of connecting tube heads arranged in a ring at equal intervals on the side wall away from the connecting plate, and fixing tubes are formed on the opposite side walls of the base and the connecting plate. The latex tube is sleeved on the connecting tube head and the fixing tube to tie the longitudinal kinetic tendon and the grasping kinetic tendon together tightly on the base, and to tie the end of the longitudinal kinetic tendon away from the base to the connecting plate.

6. A variable stiffness wrist-claw composite soft actuator according to claim 5, characterized in that, The base and the connecting plate have an initial end and an end respectively on their opposite sidewalls, and the two ends of the spiral kinetic tendon are respectively connected to the initial end and the end.

7. A variable stiffness wrist-claw composite soft actuator according to claim 5, characterized in that, The base sidewall has a first connecting joint, and the connecting plate has a second connecting joint and a third connecting joint on the sidewall opposite to the base. The first connecting joint is used to deliver gas to the grasping tendon, the second connecting joint is connected to the longitudinal tendon, and the third connecting joint is connected to the helical tendon.

8. A variable stiffness wrist-claw composite soft actuator according to claim 1, characterized in that, The bending angle range of the multiple longitudinal kinetic tendons when there is a pressure difference is 0°-50°.

9. A variable stiffness wrist-claw composite soft actuator according to claim 5, characterized in that, Each of the grasping tendons has a grasping portion and a connecting portion that are interconnected. The connecting portion is connected to the connecting tube head. The grasping portion and the connecting portion are arranged at an angle and in a U-shape.

10. A variable stiffness wrist-claw composite soft actuator according to claim 7, characterized in that, Both the second and third connecting joints have extension rings at their ends, which can work with the sealing ring to maintain airtightness with the external air circuit system.

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