Soft robot gripper and working method thereof

Abstract

The invention discloses a soft robot gripper and a working method thereof. The soft robot gripper comprises a base; the number of the clamping fingers is two, the clamping fingers are symmetrically arranged, and each clamping finger comprises a first joint and a second joint; the first SMA driving assembly comprises a first shape memory alloy, a first tendon and a first elastic bag; the second SMA driving assembly comprises a second shape memory alloy, a second tendon and a second elastic bag; two ends of the communicating pipe are respectively communicated to the first elastic bag and the second elastic bag; and the temperature control mechanism is connected with the first shape memory alloy and the second shape memory alloy. The first SMA driving assembly and the second SMA driving assembly are in a linkage relation through the first elastic bag and the second elastic bag which communicate with each other, when the first shape memory alloy extends, the second shape memory alloy can be contracted, and therefore the shape memory alloy can be driven to restore in place; and the temperature control mechanism can cool the shape memory alloy, so that the recovery of the shape memory alloy is accelerated.

Description

Technical Field

[0001] The present application relates to the field of robotics, and in particular to a soft robot gripper and a working method thereof. Background Art

[0002] In recent years, soft robots have attracted significant attention due to their compliance, strong environmental adaptability, and safety in human-robot collaboration, and their actuation methods are becoming increasingly diverse. Shape memory alloys (SMAs), a typical thermoactive smart material, offer high power density, simple actuation, and high contraction stress. They are widely used to actuate the deformation of soft robots and hold significant application value. Currently, SMA-driven soft grippers are developing rapidly and hold broad application prospects. Since grippers must achieve controllable opening and closing motion, the bidirectional actuation performance of SMAs is crucial. Existing implementation approaches include coupling elastomers with unidirectional SMAs to create antagonistic unidirectional SMA structures, and using bidirectional memory effect SMAs. The coupling of antagonistic SMAs with elastomer SMAs overcomes the limitation of bidirectional memory effect SMAs, which suffer from significant reductions in efficiency and stability under external loads. Antagonistic mechanisms employ multiple independent unidirectional SMAs to construct an antagonistic system. While bidirectional motion can be achieved, this topology requires complex thermodynamic coordination. Elastomers, on the other hand, utilize only a small number of independent SMAs, making control simpler and more convenient.

[0003] However, the elastomer solution is limited by its short development time and incomplete technology. Current soft grippers based on this approach still have limitations: since the one-way shape memory alloy can only extend through external force, although the introduction of the elastomer can extend the SMA, the SMA's elongation rate is limited by the efficiency of the ambient cooling. It is necessary to passively wait for the SMA to cool before extending it, and the driving time is long and uncontrollable. Secondly, the restoring force of the elastomer cannot be dynamically adjusted, making it difficult to achieve precise displacement control, which significantly limits the system's responsiveness and control accuracy.

[0004] On the other hand, soft robotic grippers need to open and close frequently to complete grasping and releasing movements. If traditional pneumatic, hydraulic, or mechanical mechanisms were used to drive these grippers, the overall structure would become extremely complex and redundant, hindering miniaturization. If shape-memory alloy actuators were used to control the gripper's opening and closing, simplifying the actuator structure while ensuring that it maintains grip accuracy even after repeated opening and closing poses a technical challenge currently facing the soft robotics field. Summary of the Invention

[0005] This application aims to solve at least one of the technical problems existing in the prior art. To this end, this application proposes a soft robotic gripper with more immediate SMA recovery, a simpler structure, and high gripping accuracy after multiple opening and closing cycles.

[0006] This application also proposes a working method for the above-mentioned soft robot gripper.

[0007] According to the first aspect of the present application, the soft robot gripper includes:

[0008] base;

[0009] There are two clamping fingers, which are symmetrically arranged. The clamping fingers include a first joint and a second joint. The first joint is hinged to the base, and the second joint is hinged to the first joint.

[0010] a first SMA drive assembly comprising a first shape memory alloy, a first tendon, and a first elastic bladder, wherein two ends of the first elastic bladder are respectively connected to the first joint and the base, one end of the first tendon is connected to the first joint, and the other end of the first tendon is connected to the first shape memory alloy;

[0011] a second SMA actuation assembly comprising a second shape memory alloy, a second tendon, and a second elastic bladder, wherein two ends of the second elastic bladder are respectively connected to the second joint and the first joint, one end of the second tendon is connected to the second joint, and the other end of the second tendon is connected to the second shape memory alloy;

[0012] a connecting tube, two ends of which are connected to the first elastic bladder and the second elastic bladder respectively;

[0013] A temperature control mechanism is connected to the first shape memory alloy and the second shape memory alloy, and is used to heat or cool the first shape memory alloy and the second shape memory alloy.

[0014] The soft robotic gripper according to the embodiment of the present application has at least the following beneficial effects: the first elastic sac and the second elastic sac are interconnected, so that the first SMA drive component and the second SMA drive component are linked to each other, and when the first shape memory alloy is stretched, the second shape memory alloy can be contracted, and vice versa, thereby driving the shape memory alloy to return to its position; and the temperature control mechanism can cool the shape memory alloy, thereby accelerating its recovery.

[0015] According to some embodiments of the present application, the hinge axis between the first joint and the base, and the hinge axis between the first joint and the second joint are respectively arranged at diagonal positions of the first joint.

[0016] According to some embodiments of the present application, the first elastic sac is arranged between the first tendon and the hinge axis between the first joint and the base, and the second elastic sac is arranged between the second tendon and the hinge axis between the first joint and the second joint.

[0017] According to some embodiments of the present application, both the first elastic bladder and the second elastic bladder are bellows.

[0018] According to some embodiments of the present application, fluid flows through the first elastic sac, the second elastic sac, and the connecting tube, and the fluid is gas, liquid, or a gas-liquid mixture.

[0019] According to some embodiments of the present application, the temperature control mechanism includes a first temperature control mechanism and a second temperature control mechanism, the first temperature control mechanism is connected to the first shape memory alloy, and the second temperature control mechanism is connected to the second shape memory alloy.

[0020] According to some embodiments of the present application, the first temperature control mechanism includes a first heating wire and a first fan, the first heating wire is connected to the first shape memory alloy, and the first fan is used to cool the first shape memory alloy.

[0021] According to some embodiments of the present application, the second temperature control mechanism includes a second heating wire and a second fan, the second heating wire is connected to the second shape memory alloy, and the second fan is used to cool the second shape memory alloy.

[0022] According to some embodiments of the present application, the first shape memory alloy is installed in the base, and the second shape memory alloy is installed in the first joint.

[0023] According to the second aspect of the present application, the working method for the above-mentioned soft robot gripper includes a releasing method and a clamping method;

[0024] Wherein, the release method includes:

[0025] heating the second shape memory alloy so that the second shape memory alloy contracts to drive the second tendon to retract;

[0026] The second tendon drives the second joint to turn outward;

[0027] The second elastic bladder contracts, and the pressure inside the second elastic bladder increases, forcing the fluid to flow from the second elastic bladder to the first elastic bladder;

[0028] The first elastic sac stretches, driving the first joint to flip outward, completing the outward extension movement of the robot gripper, and at the same time, the first elastic sac drives the first tendon to extend;

[0029] The first shape memory alloy is driven by the first tendon to contract;

[0030] The clamping method comprises:

[0031] heating the first shape memory alloy so that the first shape memory alloy contracts to drive the first tendon to retract;

[0032] The first tendon drives the first joint to turn inward;

[0033] The first elastic bladder contracts, and the pressure inside the first elastic bladder increases, forcing the fluid to flow from the first elastic bladder to the second elastic bladder;

[0034] The second elastic sac stretches, driving the second joint to flip inward, completing the adduction movement of the robot gripper, and at the same time, the second elastic sac drives the second tendon to extend;

[0035] The second shape memory alloy is driven by the second tendon to contract.

[0036] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become obvious from the description below, or will be learned through practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings are used to provide a further understanding of the technical solutions disclosed in this application and constitute a part of the specification. Together with the embodiments disclosed in this application, they are used to explain the technical solutions disclosed in this application and do not constitute a limitation on the technical solutions disclosed in this application.

[0038] Figure 1 A three-dimensional diagram of the soft robot gripper according to the first embodiment of the present application;

[0039] Figure 2 This is a cross-sectional view of the soft robot gripper according to the first embodiment of the present application;

[0040] Figure 3 This is a schematic diagram of the release process of the soft robot gripper in the working method of the embodiment of the second aspect of the present application;

[0041] Figure 4 This is a schematic diagram of the gripping process of the soft robot gripper in the working method of the second embodiment of the present application.

[0042] Figure markings: 100-base, 200-clamping finger, 210-first joint, 220-second joint; 310-first shape memory alloy, 320-first tendon, 330-first elastic bag, 410-second shape memory alloy, 420-second tendon, 430-second elastic bag, 500-connecting pipe, 610-first fan, 620-second fan. DETAILED DESCRIPTION

[0043] The following describes in detail embodiments of the present application. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application and are not to be construed as limiting the present application.

[0044] In the description of this application, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. 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, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on this application.

[0045] In the description of this application, "several" means more than one, "plurality" means more than two, "greater than," "less than," and "exceed" are understood to exclude the number itself, while "above," "below," and "within" are understood to include the number itself. The use of "first" and "second" in the description is solely for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, implicitly specifying the number of the indicated technical features, or implicitly specifying the order of the indicated technical features.

[0046] In the description of this application, unless otherwise clearly defined, terms such as setting, installing, and connecting should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in this application based on the specific content of the technical solution.

[0047] In the description of this application, reference to the terms "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of this application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples.

[0048] In recent years, soft robots have attracted significant attention due to their compliance, strong environmental adaptability, and safety in human-robot collaboration, and their actuation methods are becoming increasingly diverse. Shape memory alloys (SMAs), a typical thermoactive smart material, offer high power density, simple actuation, and high contraction stress. They are widely used to actuate the deformation of soft robots and hold significant application value. Currently, SMA-driven soft grippers are developing rapidly and hold broad application prospects. Since grippers must achieve controllable opening and closing motion, the bidirectional actuation performance of SMAs is crucial. Existing implementation approaches include coupling elastomers with unidirectional SMAs to create antagonistic unidirectional SMA structures, and using bidirectional memory effect SMAs. The coupling of antagonistic SMAs with elastomer SMAs overcomes the limitation of bidirectional memory effect SMAs, which suffer from significant reductions in efficiency and stability under external loads. Antagonistic mechanisms employ multiple independent unidirectional SMAs to construct an antagonistic system. While bidirectional motion can be achieved, this topology requires complex thermodynamic coordination. Elastomers, on the other hand, utilize only a small number of independent SMAs, making control simpler and more convenient.

[0049] However, the elastomer solution is limited by its short development time and incomplete technology. Current soft grippers based on this approach still have limitations: since the one-way shape memory alloy can only extend through external force, although the introduction of the elastomer can extend the SMA, the SMA's elongation rate is limited by the efficiency of the ambient cooling. It is necessary to passively wait for the SMA to cool before extending it, and the driving time is long and uncontrollable. Secondly, the restoring force of the elastomer cannot be dynamically adjusted, making it difficult to achieve precise displacement control, which significantly limits the system's responsiveness and control accuracy.

[0050] On the other hand, soft robotic grippers need to open and close frequently to complete grasping and releasing movements. If traditional pneumatic, hydraulic, or mechanical mechanisms were used to drive these grippers, the overall structure would become extremely complex and redundant, hindering miniaturization. If shape-memory alloy actuators were used to control the gripper's opening and closing, simplifying the actuator structure while ensuring that it maintains grip accuracy even after repeated opening and closing poses a technical challenge currently facing the soft robotics field.

[0051] In this regard, the present application proposes a soft robotic gripper, which enables the first SMA drive component and the second SMA drive component to achieve a linkage relationship with each other through the interconnected first elastic sac and the second elastic sac. When the first shape memory alloy stretches, the second shape memory alloy can be contracted, and vice versa, thereby driving the shape memory alloy to return to its position; and the temperature control mechanism can cool the shape memory alloy, thereby accelerating its recovery.

[0052] In addition, this application also proposes a working method for the above-mentioned soft robot gripper.

[0053] Reference Figure 1 and Figure 2 The soft robotic gripper in the embodiment of the first aspect of the present application includes a base 100, gripping fingers 200, a first SMA drive assembly, a second SMA drive assembly, a connecting pipe 500, and a temperature control mechanism. The base 100 and gripping fingers 200 together constitute the main structure of the soft robotic gripper. The gripping fingers 200 are hinged to the base 100 and can rotate about the hinge axis to complete the gripping and release of objects. The gripping fingers 200 include two joints, and the first and second SMA drive assemblies respectively control the two joints of the gripping fingers 200. The first and second SMA drive assemblies are each equipped with an elastic bladder containing fluid. The connecting pipe 500 connects the elastic bladders in the two drive assemblies to achieve a coordinated drive effect between the two drive assemblies. The temperature control mechanism acts on the first and second SMA drive assemblies to transfer heat or cold to the drive assemblies. By changing the temperature of the shape memory alloy, it causes a change in the morphology of the shape memory alloy, thereby controlling the soft robotic gripper.

[0054] Specifically, in this embodiment, there are two symmetrically arranged gripping fingers 200. It will be readily understood that the number of gripping fingers 200 may also be three or more, with the gripping and releasing actions being accomplished through the combined control of multiple gripping fingers 200. The gripping fingers 200 include a first joint 210 and a second joint 220. The first joint 210 is hingedly connected to the base 100, and the second joint 220 is hingedly connected to the first joint 210.

[0055] The first SMA actuation assembly includes a first shape memory alloy 310, a first tendon 320, and a first elastic bladder 330. The first elastic bladder 330 is connected to the first joint 210 and the base 100 at both ends, with one end of the first tendon 320 connected to the first joint 210 and the other end of the first tendon 320 connected to the first shape memory alloy 310. The first shape memory alloy 310 is mounted in the base 100. When the length of the first shape memory alloy 310 changes, a force is applied to the first joint 210 via the first tendon 320, thereby driving the first joint 210 to rotate about its hinge axis, thereby causing the first elastic bladder 330 to deform.

[0056] The second SMA actuation assembly includes a second shape memory alloy 410, a second tendon 420, and a second elastic bladder 430. The two ends of the second elastic bladder 430 are connected to the second joint 220 and the first joint 210, respectively. One end of the second tendon 420 is connected to the second joint 220, and the other end of the second tendon 420 is connected to the second shape memory alloy 410. The second shape memory alloy 410 is mounted in the first joint 210. When the length of the second shape memory alloy 410 changes, a force is applied to the second joint 220 via the second tendon 420, thereby driving the second joint 220 to rotate about its hinge axis, thereby causing the second elastic bladder 430 to deform.

[0057] The two ends of the connecting tube 500 are connected to the first elastic sac 330 and the second elastic sac 430, respectively, enabling interconnection between the first elastic sac 330 and the second elastic sac 430. For example, when the first shape memory alloy 310 contracts due to heat, the first elastic sac 330 contracts, its internal pressure increases, and fluid flows from the first elastic sac 330 into the second elastic sac 430, causing the second elastic sac 430 to expand and elongate. When the second shape memory alloy 410 contracts due to heat, the second elastic sac 430 contracts, its internal pressure increases, and fluid flows from the second elastic sac 430 into the first elastic sac 330, causing the first elastic sac 330 to expand and elongate. This achieves the linkage between the first and second SMA drive components, and makes it easier for the shape memory alloy to return to its original position, improving clamping accuracy and preparing for subsequent frequent opening and closing.

[0058] The temperature control mechanism is connected to the first shape memory alloy 310 and the second shape memory alloy 410 , and is used to heat or cool the first shape memory alloy 310 and the second shape memory alloy 410 , so that the shape memory alloys can convert thermal energy into mechanical energy.

[0059] Furthermore, the hinge axis between the first joint 210 and the base 100, and the hinge axis between the first joint 210 and the second joint 220 are respectively arranged at diagonal positions of the first joint 210, so as to facilitate the control of the first joint 210 and the second joint 220 to flip in different directions.

[0060] Furthermore, the first elastic bag 330 is disposed between the first tendon 320 and the hinge axis between the first joint 210 and the base 100 , and the second elastic bag 430 is disposed between the second tendon 420 and the hinge axis between the first joint 210 and the second joint 220 .

[0061] Specifically, the first elastic bladder 330 and the second elastic bladder 430 can be air bladders, water bladders, or other elastomeric structures capable of expansion and contraction. In this embodiment, the first elastic bladder 330 and the second elastic bladder 430 are both bellows. The characteristic of bellows is that their deformation direction is predictable, preventing excessive lateral deformation from interfering with the robot gripper structure.

[0062] The fluid flowing through the first elastic bladder 330, the second elastic bladder 430, and the connecting tube 500 can be a gas, a liquid, or a gas-liquid mixture. The specific type of fluid can be adjusted and replaced according to actual conditions. As for the volume of fluid filled in the first elastic bladder 330 and the second elastic bladder 430, as well as the ratio of gas to liquid in the gas-liquid mixture, they can also be increased or decreased according to actual conditions. By adjusting the ratio of gas to liquid in the gas-liquid mixture, the gripping force of the gripper can be changed. The greater the proportion of liquid, the greater the fluid pressure and the greater the gripping force, thereby improving the rigidity of the SMA drive assembly.

[0063] Furthermore, the temperature control mechanism includes a first temperature control mechanism and a second temperature control mechanism. The first temperature control mechanism is connected to the first shape memory alloy 310 to transfer heat thereto, and the second temperature control mechanism is connected to the second shape memory alloy 410 to transfer heat thereto.

[0064] Furthermore, the first temperature control mechanism includes a first heating wire and a first fan 610. The first heating wire is connected to the first shape memory alloy 310. When current is passed through the first heating wire, it generates heat, thereby transferring heat to the first shape memory alloy 310. The first fan 610 is used to cool the first shape memory alloy 310 and accelerate its recovery.

[0065] Furthermore, the second temperature control mechanism includes a second heating wire and a second fan 620. The second heating wire is connected to the second shape memory alloy 410. When current is supplied to the second heating wire, it heats up, thereby transferring heat to the second shape memory alloy 410. The second fan 620 is used to cool the second shape memory alloy 410.

[0066] A working method for the above-mentioned soft robot gripper in an embodiment of the second aspect of the present application includes a releasing method and a clamping method;

[0067] Among them, reference Figure 3 , the release method includes the following steps:

[0068] S110. The second shape memory alloy 410 is heated, and the second shape memory alloy 410 contracts to drive the second tendon 420 to retract;

[0069] S120. The second tendon 420 drives the second joint 220 to flip outward;

[0070] S130. The second elastic bladder 430 contracts, and the pressure inside the second elastic bladder 430 increases, forcing the fluid to flow from the second elastic bladder 430 to the first elastic bladder 330;

[0071] S140. The first elastic capsule 330 stretches, driving the first joint 210 to flip outward, completing the outward movement of the robot gripper, while the first elastic capsule 330 drives the first tendon 320 to extend;

[0072] S150. The first shape memory alloy 310 is driven by the first tendon 320 to contract, and the first shape memory alloy 310 returns to its original position to wait for the next extension.

[0073] Reference Figure 4 , the gripping methods include:

[0074] S210. The first shape memory alloy 310 is heated, and the first shape memory alloy 310 contracts to drive the first tendon 320 to retract;

[0075] S220. The first tendon 320 drives the first joint 210 to flip inward;

[0076] S230. The first elastic sac 330 contracts, and the pressure inside the first elastic sac 330 increases, forcing the fluid to flow from the first elastic sac 330 to the second elastic sac 430;

[0077] S240. The second elastic capsule 430 stretches, driving the second joint 220 to flip inward, completing the adduction movement of the robot gripper, while the second elastic capsule 430 drives the second tendon 420 to extend;

[0078] S250. The second shape memory alloy 410 is driven by the second tendon 420 to contract, and the second shape memory alloy 410 returns to its original position to wait for the next extension.

[0079] The embodiments of the present application have been described in detail above with reference to the accompanying drawings. However, the present application is not limited to the above embodiments. Various modifications can be made within the scope of knowledge possessed by ordinary technicians in the relevant technical field without departing from the purpose of the present application. In addition, the embodiments of the present application and the features of the embodiments can be combined with each other unless there is a conflict.

Claims

1. A soft robot gripper, characterized in that: include: base; There are two clamping fingers, which are symmetrically arranged. The clamping fingers include a first joint and a second joint. The first joint is hinged to the base, and the second joint is hinged to the first joint. a first SMA drive assembly comprising a first shape memory alloy, a first tendon, and a first elastic bladder, wherein two ends of the first elastic bladder are respectively connected to the first joint and the base, one end of the first tendon is connected to the first joint, and the other end of the first tendon is connected to the first shape memory alloy; a second SMA actuation assembly comprising a second shape memory alloy, a second tendon, and a second elastic bladder, wherein two ends of the second elastic bladder are respectively connected to the second joint and the first joint, one end of the second tendon is connected to the second joint, and the other end of the second tendon is connected to the second shape memory alloy; a connecting tube, two ends of which are connected to the first elastic bladder and the second elastic bladder respectively; A temperature control mechanism is connected to the first shape memory alloy and the second shape memory alloy, and is used to heat or cool the first shape memory alloy and the second shape memory alloy.

2. The soft robot gripper according to claim 1, characterized in that: The hinge axis between the first joint and the base, and the hinge axis between the first joint and the second joint are respectively arranged at diagonal positions of the first joint.

3. The soft robot gripper according to claim 2, characterized in that: The first elastic bag is arranged between the first tendon and the hinge axis between the first joint and the base, and the second elastic bag is arranged between the second tendon and the hinge axis between the first joint and the second joint.

4. The soft robotic gripper according to claim 1, characterized in that: The first elastic bag and the second elastic bag are both bellows.

5. The soft robot gripper according to claim 1, characterized in that: Fluid flows through the first elastic bag, the second elastic bag and the connecting tube, and the fluid is gas, liquid or a gas-liquid mixture.

6. The soft robotic gripper according to claim 1, characterized in that: The temperature control mechanism includes a first temperature control mechanism and a second temperature control mechanism, the first temperature control mechanism is connected to the first shape memory alloy, and the second temperature control mechanism is connected to the second shape memory alloy.

7. The soft robot gripper according to claim 6, characterized in that: The first temperature control mechanism includes a first heating wire and a first fan. The first heating wire is connected to the first shape memory alloy. The first fan is used to cool the first shape memory alloy.

8. The soft robot gripper according to claim 6, characterized in that: The second temperature control mechanism includes a second heating wire and a second fan, the second heating wire is connected to the second shape memory alloy, and the second fan is used to cool the second shape memory alloy.

9. The soft robotic gripper according to claim 1, characterized in that: The first shape memory alloy is installed in the base, and the second shape memory alloy is installed in the first joint.

10. A method for operating the soft robot gripper according to any one of claims 1 to 9, characterized in that: including release methods and gripping methods; Wherein, the release method includes: heating the second shape memory alloy so that the second shape memory alloy contracts to drive the second tendon to retract; The second tendon drives the second joint to turn outward; The second elastic bladder contracts, and the pressure inside the second elastic bladder increases, forcing the fluid to flow from the second elastic bladder to the first elastic bladder; The first elastic sac stretches, driving the first joint to flip outward, completing the outward extension movement of the robot gripper, and at the same time, the first elastic sac drives the first tendon to extend; The first shape memory alloy is driven by the first tendon to contract; The clamping method comprises: heating the first shape memory alloy so that the first shape memory alloy contracts to drive the first tendon to retract; The first tendon drives the first joint to turn inward; The first elastic bladder contracts, and the pressure inside the first elastic bladder increases, forcing the fluid to flow from the first elastic bladder to the second elastic bladder; The second elastic sac stretches, driving the second joint to flip inward, completing the adduction movement of the robot gripper, and at the same time, the second elastic sac drives the second tendon to extend; The second shape memory alloy is driven by the second tendon to contract.

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