Modular bistable flexible grasping device and sea-air cross-medium robot

Abstract

The application discloses a modular bistable flexible grasping device and a sea-air cross-medium robot, and relates to the technical field of robots, in particular to a modular bistable flexible grasping device and a sea-air cross-medium robot. The modular bistable flexible grasping device comprises a mounting base, an excitation driving unit and at least two bistable execution units. The bistable execution unit comprises a bistable bending spring and a connecting assembly. Each bistable bending spring is circumferentially arranged on the mounting base through the connecting assembly. The bistable bending spring has two stable states of an unfolded configuration and a closed configuration in a natural state, and remains in any configuration without continuous energy input. The excitation driving unit comprises a driving source and a driving assembly. The driving source is mounted on the mounting base, and the driving assembly is connected to the output end of the driving source. The driving assembly is in transmission connection with the root of each bistable bending spring, so as to drive the bistable bending spring to switch between the unfolded configuration and the closed configuration. The application can realize a fast, stable and low-disturbance grasping action, and has a light structure.

Description

Technical Field

[0001] This invention relates to the field of special-purpose robots, specifically to a modular bistable flexible grasping device for a sea-air cross-medium robot and a sea-air cross-medium robot. Background Technology

[0002] Aquamarine-sea cross-medium robots are an emerging type of robot capable of operating in both water and air and repeatedly crossing the water-air interface, with broad application prospects in both military and civilian fields. Currently, although a certain research progress has been made in environmental monitoring, aquamarine-sea cross-medium robots still suffer from limited functionality in practical applications and generally lack effective underwater precision operation capabilities.

[0003] Existing underwater grasping devices still face the following key challenges in being integrated into sea-and-air cross-medium robots and achieving effective underwater operations: Structural redundancy and excessive weight: Traditional rigid gripping mechanisms typically employ complex structures with multiple transmission components such as motors, linkages, and gears connected in series. While these systems have high integration, they are also quite heavy. The payload capacity of cross-media robots is extremely limited, placing stringent demands on the lightweight design of the mounting equipment. Existing flexible gripping solutions, while pneumatic or hydraulic drives can achieve rapid response, result in large and heavy auxiliary systems such as drive pumps, air sources, and control valve assemblies, which also struggle to meet the mounting constraints of cross-media platforms. Using small, lightweight drive pumps often comes at the cost of reduced drive efficiency and output force, leading to low overall system energy efficiency. Therefore, gripping devices not only require lightweight structural design but also need breakthroughs at the drive principle level to achieve coordinated weight reduction of the drive system and the actuator.

[0004] High energy consumption and limited continuous operation: Most existing flexible grasping devices rely on continuous energy input to maintain the grasping closure state, resulting in high overall energy consumption. For cross-media robots that rely on limited onboard energy to perform long-duration tasks, high energy consumption means a significantly shortened operating window. In particular, schemes that use active drive to maintain the grasping state continue to consume energy during standby or target holding phases, resulting in low energy utilization and making it difficult to meet the stringent endurance requirements of practical applications.

[0005] Slow dynamic response and weak underwater disturbance resistance: The underwater environment, with its high density and high viscosity, places higher demands on the dynamic response capabilities of the grasping mechanism. Traditional grasping devices, due to long transmission chains and drive lag, struggle to complete the closing action within millisecond-level time windows. In dynamic scenarios involving water flow disturbances, platform attitude fluctuations, or target movement, a slow grasping response directly impacts the success rate. Furthermore, even if the grasping device can close, if its structural design does not adequately consider hydrodynamic characteristics, the device's own movement and interaction with the fluid during grasping or target transfer can easily generate additional disturbance forces, leading to target slippage or positional deviation. Especially when using an envelope-type grasping mechanism, if the solid structure of the grasping device is too large, it will compress the water during the closing process, forming a local jet that reacts against the target object, severely affecting grasping accuracy. Therefore, grasping devices need to optimize their hydrodynamic performance at the structural level to reduce fluid resistance and disturbances during movement, thereby improving the stability and success rate of underwater operations.

[0006] Limited Functionality and Difficulty in Structural Reconfiguration: For diverse underwater operations, gripping mechanisms must possess reconfigurable functionality. For example, when collecting samples from jellyfish, octopuses, or other soft-bodied organisms, the gripping device must have excellent enveloping properties to achieve non-destructive encapsulation; while when collecting seabed sediments, ores, or regular structural components, a simple two-finger gripping configuration suffices, offering greater precision and efficiency. However, existing gripping devices are mostly fixed in configuration, with the number of fingers, their layout, and gripping modes unable to be flexibly adjusted according to the task, limiting their applicability in multi-tasking scenarios. Therefore, gripping devices should adopt a modular design concept, supporting rapid switching between structural form and functional modes to adapt to different operational objects, environmental conditions, and task objectives, achieving "one machine, multiple uses" operational capabilities.

[0007] In summary, for the special application scenarios of marine and air cross-media robots, there is an urgent need to develop an underwater grasping device that combines lightweight structure, low energy consumption, rapid response capability, low water resistance, and modular reconfigurability to meet their requirements for precise, efficient, and stable operation on diverse targets in complex underwater environments.

[0008] The above background information is provided only to aid in understanding the concept and technical solution of this invention. It does not necessarily belong to the prior art of this patent application. In the absence of clear evidence that the above information was disclosed on the filing date of this patent application, the above background information should not be used to evaluate the novelty and inventiveness of this application. Summary of the Invention

[0009] To address the aforementioned technical problems, this invention proposes a modular bistable flexible grasping device and a sea-air cross-medium robot. This device can achieve fast, stable, and low-disturbance grasping actions without relying on continuous energy input to maintain the grasping state. Furthermore, it has a lightweight structure and is easy to modularly reconfigure according to task requirements to meet the stringent requirements of sea-air cross-medium robot platforms.

[0010] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention discloses a modular bistable flexible grasping device, comprising a mounting base, an excitation and driving unit, and at least two bistable execution units, wherein... The bistable actuation unit includes a bistable bending spring and a connecting assembly. Each of the bistable bending springs is mounted on the mounting base in a circumferential arrangement through the connecting assembly. The bistable bending spring has two stable states in its natural state: an unfolded configuration and a closed configuration, and remains in either configuration without continuous energy input. The excitation driving unit includes a driving source and a driving component. The driving source is mounted on the mounting base, and the driving component is connected to the output end of the driving source. The driving component is respectively connected to the root of each of the bistable bending springs to drive the bistable bending springs to switch between the unfolded configuration and the closed configuration.

[0011] Preferably, the bistable bending spring is composed of a U-shaped spring base and a spring clip, wherein the two ends of the U-shaped spring base are fastened and fixed by the spring clip to form a pre-compression stress.

[0012] Preferably, the U-shaped spring substrate is made of polypropylene with a thickness of 0.5mm to 1.2mm.

[0013] Preferably, the mounting base has multiple mounting interfaces along the circumferential direction. The connecting assembly includes a spring clip fixing member and a locking ring. One end of the spring clip fixing member is fixedly connected to the root of the bistable bending spring clip. The other end of the spring clip fixing member has a protruding column. The end of the column is inserted into the mounting interface and passes through the mounting base to be fixedly connected with the locking ring.

[0014] Preferably, the excitation driving unit adopts a rotary iris driving mechanism, the driving source drives the driving component to rotate, and the driving component drives the root of each bistable bending spring to move in the radial direction, so as to drive the bistable bending spring to switch between the unfolded configuration and the closed configuration.

[0015] Preferably, the driving assembly includes a central driving member, a limiting plate, and at least two connecting rods. The output end of the driving source is connected to the central driving member to drive the central driving member to rotate. The limiting plate is mounted on the mounting base. The central driving member has a curved groove, and the limiting plate has radially distributed straight guide grooves. The first end of each connecting rod is simultaneously limited in the curved groove and the straight guide groove, and the second end of each connecting rod is fixedly connected to the root of each bistable bending spring.

[0016] Preferably, each of the bistable bending springs has a root connection interface at its root, and the second end of each connecting rod is connected to the root connection interface of each of the bistable bending springs.

[0017] Preferably, the drive assembly further includes at least two guide members, which are fixedly connected to the mounting base or the limiting plate. The guide members have guide holes, and the second end of each connecting rod passes through the guide hole.

[0018] Preferably, the bistable actuation unit further includes a mesh barrier, which is attached and fixed to the inner and / or outer side of the bistable bending spring.

[0019] Secondly, the present invention discloses a sea-air cross-medium robot, including a robot body, wherein the robot body is equipped with a modular bistable flexible grasping device as described in the first aspect.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: The modular bistable flexible grasping device disclosed in the present invention uses a bistable bending spring with bistable characteristics as the execution unit, and is combined with an excitation drive unit for synchronous excitation, so that the entire device only needs energy input at the moment of configuration switching, and does not need continuous power supply during the grasping state maintenance phase, thus achieving an extremely low energy consumption level; moreover, the potential energy reversal mechanism of the bistable structure makes the configuration switching process extremely fast, and can achieve fast, stable, and low-disturbance grasping action without the need for air source and cable transmission. In addition, the structure is lightweight and easy to be modularly reconfigured according to task requirements to adapt to cross-media robot platforms with stringent requirements for load capacity, energy consumption and response speed.

[0021] In a further embodiment, the present invention also has the following beneficial effects: (1) The bistable bending spring is formed by fastening the two ends of the U-shaped spring base through the spring lock. The U-shaped structure not only helps to form pre-compression stress to achieve bistable characteristics, but also the hollow area naturally formed on its inner side helps to reduce water resistance and fluid disturbance during the grabbing process, and improve the stability of underwater grabbing.

[0022] (2) By limiting the U-shaped spring substrate to use polypropylene material with a specific thickness range, while ensuring that the spring has good bistable characteristics and sufficient stiffness, the weight of the actuator is further realized. Moreover, the polypropylene material provides good elasticity, memory and corrosion resistance, making it suitable for underwater environments.

[0023] (3) The bistable actuator adopts a modular design and can be detachably installed on the mounting base through specific connecting components. This allows users to quickly replace different numbers (e.g., two-finger, four-finger) or different parameters of bistable actuators according to different work objects (e.g., soft organisms that need to be enveloped for grasping or regular objects that need to be gripped). This realizes the reconfigurability of the grasping device's functional mode and improves the equipment's versatility and task adaptability. Furthermore, through the cooperation of the spring clip fixing part, column, mounting interface and locking ring, the actuator can be quickly installed and locked, making operation simple.

[0024] (4) By designing the excitation drive unit as a rotary iris drive mechanism and using a single drive source to synchronously drive all bistable execution units through the drive components, the coordinated action of the multi-finger mechanism is realized. This not only ensures the consistency and reliability of the grasping action, but also greatly simplifies the drive structure, reduces the number of parts and the overall weight, which is beneficial to the lightweight design of cross-media robots.

[0025] (5) Through the cooperation of the central drive component, the limiting plate, and the connecting rod, the rotational motion of the drive source is accurately converted into the radial linear motion of each connecting rod. The transmission chain is short, the efficiency is high, and the response is fast, which further improves the lightweight and fast response characteristics of the device. Furthermore, by adding a guide component and providing a guide hole for the second end of the connecting rod, the stability and accuracy of the connecting rod during the movement process are further enhanced.

[0026] (6) By setting up mesh barriers, the ability to capture and retain specific targets (such as small organisms) can be enhanced without seriously affecting the mechanical properties and movement of the shrapnel, thus expanding the application scenarios of the device.

[0027] (7) The present invention also provides a sea-air cross-medium robot, which, by being equipped with any of the above-mentioned modular bistable flexible grasping devices, enables the robot to obtain lightweight, low-energy, fast-response, and reconfigurable underwater grasping capabilities, significantly enhancing its active operation and work capabilities underwater.

[0028] Other beneficial effects of the embodiments of the present invention will be further described below. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the overall structure of the four-finger gripping device of the present invention in the closed state; Figure 2This is a schematic diagram of the overall structure of the four-finger gripping device of the present invention in the unfolded state; Figure 3 This is a schematic diagram of the overall structure of the two-finger gripping device of the present invention in the closed state; Figure 4 This is a schematic diagram of the bistable execution unit in this invention; Figure 5 This is a side top view of the excitation driving unit in this invention; Figure 6 This is a side-view of the excitation drive unit in this invention; Figure 7 This is a schematic diagram of the modular mounting base in this invention.

[0030] Explanation of reference numerals in the attached figures: 1-Bistable actuator, 11-Bistable bending spring, 12-Spring fixing component, 121-Female buckle seat, 1211-Column, 122-Male buckle cover, 13-Locking ring, 14-Root connection interface, 15-Spring buckle latch; 2-Actuation drive unit, 21-Miniature servo motor, 22-Rudder disk, 23-Center drive component, 231-Curved groove, 24-Lower limiting plate, 241-Linear guide groove, 25-Connecting rod, 26-Guide component; 3-Modular mounting base, 31-Mounting interface, 32-Central drive component fixing slot, 33-Lower limit plate fixing slot; 4-Grip device mounting base. Detailed Implementation

[0031] The embodiments of the present invention will be described in detail below. It should be emphasized that the following description is merely exemplary and is not intended to limit the scope and application of the present invention.

[0032] It should be noted that when a component is referred to as "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as "connected to" another component, it can be directly connected to or indirectly connected to that other component. Furthermore, a connection can be used for both fixing and circuit / signal connectivity.

[0033] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention 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. Therefore, they should not be construed as limitations on the present invention.

[0034] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of the present invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0035] To address the technical challenges faced by existing underwater grasping devices when integrated into sea-and-air cross-medium robots, such as structural redundancy, excessive weight, high energy consumption, slow dynamic response, and limited functional modes, this invention provides a modular bistable flexible grasping device based on the bistable structural principle. This device aims to enhance the active operation capabilities of cross-medium robots in underwater environments, enabling precise, rapid, non-destructive, and low-energy grasping of complex targets.

[0036] like Figures 1 to 3 As shown, the modular bistable flexible gripping device disclosed in the preferred embodiment of the present invention includes a mounting base, an excitation and driving unit 2, and at least two bistable execution units 1. The mounting base includes a modular mounting base 3 and a gripping device mounting base 4. The bistable execution unit 1 includes bistable bending springs and connecting components. Each bistable bending spring is mounted on the modular mounting base in a circumferential arrangement through the connecting components. The bistable bending springs have two stable states in their natural state: an unfolded configuration and a closed configuration, and remain in either configuration without continuous energy input. The excitation and driving unit 2 includes a driving source and a driving component. The driving source is mounted on the modular mounting base, and the driving component is connected to the output end of the driving source. The driving component is drivenly connected to the root of each bistable bending spring to drive the bistable bending springs to switch between the unfolded and closed configurations.

[0037] There can be two, three, four, or more bistable execution units 1, arranged in a circular direction, each of which is an independent structural module. Figure 1 and Figure 2 The overall structure of the four-finger configuration, which includes four bistable actuation units 1, is shown in both the closed and expanded states. Figure 3 The structure of the bifinite configuration containing two bistable execution units 1 in the closed state is shown.

[0038] like Figure 4As shown, the bistable actuation unit 1 is composed of a bistable bending spring 11 with bistable characteristics. In this embodiment, the bistable bending spring 11 is made of polypropylene (PP) with a thickness of 0.5-1.2 mm. The manufacturing process is as follows: a sheet-like structure made of polypropylene is pre-cut into a U-shape to form a U-shaped spring substrate. The two ends of the U-shaped spring substrate are then fastened together using spring clips 15. The spring clips 15 are circular male-female clip structures, including mating male and female clips, which reliably connect the two ends of the U-shaped spring substrate after fastening. Because PP material has good elasticity and memory properties, and the two ends of the U-shaped spring substrate are pre-compressed after fixing, the bistable bending spring 11 has two stable states, forming a clear bistable energy barrier: in the unfolded state, the bottom of the bistable bending spring 11 arches outward; in the closed state, the bottom of the bistable bending spring 11 contracts inward. Switching between the two stable states requires overcoming the elastic barrier of the U-shaped spring substrate. After switching, it can maintain itself in either stable state without external force, thus obtaining bistable characteristics. Therefore, the bistable bending spring 11 in this embodiment has two directional stable configurations in its natural state, and exhibits the following characteristics after assembly: Figures 1 to 3 The expanded and closed configurations in [the text]. (See reference.) Figure 2 In the unfolded configuration, the bistable bending spring 11 unfolds radially; Reference Figure 1 and Figure 3 In the closed configuration, the bistable bending spring 11 contracts inward to form an envelope space, forming a cage-like structure that enables compliant grasping of the target. The bistable characteristic allows each bistable actuator 1 to stably maintain any configuration without continuous energy input.

[0039] In addition to using polypropylene, which has good fatigue resistance, the U-shaped spring substrate of the bistable bending spring 11 can also be made of other engineering plastics or composite materials with high fatigue resistance in some other embodiments.

[0040] The bistable bending spring 11 is formed from a U-shaped spring substrate with a U-shaped structure. After the two ends of the U-shaped spring substrate are fastened and fixed by spring clips 15, a permeable hollow area is naturally formed on its inner side. Based on the basic principles of fluid mechanics, this can reduce local jet disturbance. The mechanism is as follows: When the gripping device switches from the unfolded state to the closed state, the volume of the envelope space enclosed by the springs decreases rapidly, and the water inside needs to be discharged. For solid springs, water can only be discharged from the narrow gap between the end of the spring and the target, resulting in a sharp increase in water velocity, forming a local jet impact on the target, causing the target to deviate or escape. However, the embodiment of the present invention adopts a U-shaped hollow structure, and the inner side of the spring is a naturally hollow area. During the closing process, the water can be discharged from the following paths: ① Hollow area on the inner side of the spring: the water flows out directly through the inner side of the U-shape, with a large flow area; ② Gap between the springs: the water is discharged from the gap between the fingers; ③ Opening at the end of the spring: the water is discharged from the bottom of the envelope space. Furthermore, according to the fluid continuity equation Q = A·v (flow rate = flow area × velocity), under the same drainage flow rate Q, the larger the flow area A, the smaller the velocity v. This invention provides additional drainage channels through a U-shaped hollow structure, significantly increasing the total flow area, thereby reducing the water discharge velocity and the impact force on the target. This not only effectively reduces local jet disturbance and improves grasping stability, but also effectively reduces the fluid resistance of the grasping device during underwater movement, improving grasping accuracy.

[0041] The root of the bistable bending spring 11 is mounted on the modular mounting base 3 via a connecting assembly. (Reference) Figure 4 The connecting assembly includes a spring clip fixing member 12 and a locking ring 13, used to install the bistable bending spring clip 11 onto the modular mounting base 3. The spring clip fixing member 12 includes a female buckle 121 and a male buckle cap 122, wherein the female buckle 121 is fixed to one side of the root of the bistable bending spring clip 11, and the male buckle cap 122 is connected to the female buckle 121 by a male-female fastening method, clamping and fixing the root of the bistable bending spring clip 11. A column 1211 protrudes from the female buckle 121, and the end of the column 1211 is inserted into the mounting interface 31 provided on the modular mounting base 3 and protrudes from the modular mounting base 3 to be fixedly connected with the locking ring 13. That is, the locking ring 13 is used to fit on the upper part of the spring clip fixing member 12 after the spring clip fixing member 12 is fitted onto the modular mounting base 3, so that the bistable bending spring clip 11 is fixed on the modular mounting base 3. The bistable bending spring 11 is also provided with a root connection interface 14 at its root for connecting to the connecting rod 25 of the excitation drive unit 2.

[0042] The perforated, water-permeable structure of the bistable bending spring 11 in this embodiment is naturally formed by the U-shaped spring substrate itself, without the need for additional processing of through holes or mesh structures. The key geometric parameters of the U-shaped spring substrate include width W, length L, and opening angle θ. Width W affects the spring stiffness and the contact area with the fluid; length L affects the size of the envelope space and the response speed; and opening angle θ affects the size of the perforated area and the water flow. These parameters collectively influence the underwater performance of the bistable bending spring 11. When forming the perforated structure and selecting parameters, priority should be given to ensuring the reliable flipping and gripping functions of the bistable structure. Based on this, U-shaped springs with different aspect ratios and opening angles exhibit differences in excitation speed and excitation difficulty: springs with larger aspect ratios (narrow and long) have faster excitation speeds but lower stiffness, suitable for scenarios requiring rapid response; springs with smaller aspect ratios (wide and short) have higher stiffness but slower excitation speeds, suitable for scenarios requiring greater gripping force. Users can select appropriate spring parameters as needed based on specific operational requirements (such as target size, water flow conditions, grasping speed requirements, etc.).

[0043] In addition to width W, length L, and opening angle θ, the geometric parameters of a bistable bending spring also include thickness h, radius of curvature ρ, and bending path L_path. These parameters can be optimized based on the size and mechanical properties of the target object to achieve non-destructive gripping. Specifically, the thickness h can be selected based on the mechanical properties of the target object: for fragile targets such as soft organisms, a thinner spring (0.6-0.8mm) is used to reduce gripping force and avoid damage; for hard targets such as sediments, a thicker spring (0.8-1.2mm) is used to provide sufficient gripping force. The thickness range of the spring is determined by mechanical calculations and prototype testing based on the elastic modulus and yield strength of the polypropylene material and the target gripping force requirements. The radius of curvature ρ can be selected based on the size of the target object: the radius of curvature determines the size of the envelope space in the closed state, usually taken as half of the target diameter D (ρ≈D / 2), so that the spring can envelop the target after closure. The approximate relationship between the radius of curvature and the target diameter is initially set based on the spatial geometry requirements of the envelope gripping, and can be adjusted within a certain range according to the target shape in practical applications. The bending path L_path can be selected based on the size of the target object and the required degree of envelope: the bending path is usually 0.8-1.2 times the length of the spring, and the excitation force and response speed can be balanced by adjustment.

[0044] The excitation drive unit 2 employs a rotary iris drive mechanism. The drive source drives the drive assembly to rotate, and the drive assembly moves the roots of each bistable bending spring 11 radially, thereby driving the bistable bending spring 11 to switch between an unfolded configuration and a closed configuration. Specifically, the drive source uses a servo motor, which drives the drive assembly to move axially or circumferentially, synchronously driving the root connection points of each bistable bending spring 11, causing the bistable bending spring 11 to cross the potential barrier and rapidly flip from an unfolded configuration to a closed configuration, completing the dynamic excitation of the grasping action. Specifically, as shown... Figure 5 and Figure 6 As shown, the excitation drive unit 2 includes a micro servo motor 21, a servo disk 22, a central drive component 23, a lower limiting plate 24, a connecting rod 25, and a guide component 26, forming a rotary iris drive mechanism. The micro servo motor 21 is fixed on the gripping device mounting base 4, and its output shaft is connected to the servo disk 22. The central drive component 23 is installed in the central drive component fixing slot 32 of the modular mounting base 3 and can rotate under the drive of the servo disk 22. The central drive component 23 has a curved groove 231. The lower limiting plate 24 is installed in the lower limiting plate fixing slot 33 of the modular mounting base 3, and has several radially distributed straight guide grooves 241. The guide component 26 is fixed to the outside of the modular mounting base 3 and has holes. One end of the connecting rod 25 is connected to the curved groove 231 of the central drive member 23 and the straight guide groove 241 of the lower limiting piece 24 by a half thread screw; the other end of the connecting rod 25 is cylindrical and passes through the guide hole of the guide member 26, and is connected to the root connection interface 14 on the bistable bending spring 11 in the middle. Its driving principle is as follows: the rotational motion of the micro servo motor 21 drives the central drive component 23 to rotate through the servo disk 22; the curved groove 231 on the central drive component 23 drives the connecting rod 25 to move; since one end of the connecting rod 25 is connected to both the curved groove 231 of the central drive component 23 and the straight guide groove 241 of the lower limiting plate 24 by a half-threaded screw, under the double limiting action, the connecting rod 25 can only make precise radial linear sliding along the straight guide groove 241; the hole in the middle of the connecting rod 25 is connected to the root connection interface 14 on the bistable bending spring 11, transmitting the radial motion to the root of the bistable bending spring 11, so that the bistable bending spring 11 crosses the potential barrier and completes the flip. This excitation drive unit 2 directly converts the rotational motion of the micro servo motor 21 into the radial synchronous motion of multiple bistable actuators 1, with a compact structure, high transmission accuracy, and multi-finger synchronous precise excitation. Among them, the guide component 26 is fixed and only plays a limiting and guiding role, ensuring that the motion trajectory of the connecting rod 25 is accurate and reliable.

[0045] like Figure 7As shown, the modular mounting base 3 serves as a support platform, on which several standard mounting interfaces 31 arranged in a circular array are provided for independently installing each bistable actuator 1. The mounting interface 31 is a circular hole; the bottom of the spring clip fixing member 12 (female buckle 121) at the root of the bistable bending spring 11 is provided with a cylindrical rod that matches the mounting interface 31, so that the mounting interface 31 matches the spring clip fixing member 12 at the root of the bistable bending spring 11, enabling quick installation and removal of the bistable actuator 1. During installation, the cylindrical rod on the spring clip fixing member 12 at the root of the bistable bending spring 11 is inserted into the circular hole of the modular mounting base 3, and then the locking ring 13 is fitted onto the cylindrical rod and pushed to a position tightly against the modular mounting base 3. The locking ring 13 is an open circular ring with a certain degree of elasticity. It is fitted onto the cylindrical rod of the female buckle 121, forming an interference fit. Once the locking ring 13 is engaged, its elastic deformation generates a clamping force, securing the bistable actuator 1 to the modular mounting base 3 and preventing loosening. Disassembly can be performed by hand, pulling out (or pushing away) the locking ring 13, and then pulling the cylindrical rod out of the hole in the mounting interface 31. The entire process requires no tools and is simple and quick. In this embodiment, the modular mounting base 3 supports the rapid replacement of different numbers and configurations of bistable actuators to adapt to the needs of different work objects and task scenarios. The modular mounting base 3 has a central drive component fixing groove 32 for installing and limiting the central drive component 23; its lower part has a lower limiting plate fixing groove 33 for installing and limiting the lower limiting plate 24.

[0046] The gripping device mounting base 4 is located at the top of the device and is used to fix the entire gripping device to the cross-media robot platform.

[0047] The modular mounting base 3, in addition to supporting the excitation drive unit 2, also provides a standard mechanical and electrical interface with the cross-medium robot platform. For electrical connections, the power supply and control cables for the micro servo 21 use standard DuPont wires, directly leading out from the micro servo 21. After exiting, the cables run along the frame structure of the cross-medium robot platform, ultimately passing through the waterproof chamber interface and entering the interior of the waterproof chamber, where they connect to the servo control board and flight control system. The cable layout fully considers space avoidance with the various moving parts of the gripping device (such as the bistable bending spring 11, connecting rod 25, guide 26, etc.), ensuring that the cables do not interfere with or entangle with any components during the deployment, closure, and movement of the gripping device. It should be noted that this embodiment of the invention claims protection for the gripping device itself; the frame, waterproof chamber, and its internal servo control board, flight control system, etc., are components of the cross-medium robot platform and are therefore not shown in the accompanying drawings. The gripping device is connected to the platform only through a mechanical interface. The electrical connection is handled and integrated by the platform. The gripping device itself does not have wire holes or wiring channels to avoid increasing structural complexity and potential interference risks.

[0048] Users can flexibly choose the number and layout of bistable execution units 1 according to the requirements of the task: when performing tasks requiring high envelope, such as soft biological sampling, four sets of bistable execution units 1 can be installed to form a four-finger configuration, such as... Figure 1 and Figure 2 As shown; when performing tasks such as grasping sediments or regular objects, two sets of bistable actuators 1 can be installed to form a two-finger configuration, such as... Figure 3 As shown. Each execution unit can be installed and replaced independently, enabling rapid reconfiguration of the gripping device's structure and functional mode.

[0049] In a further embodiment, for operational scenarios requiring higher envelope performance, such as marine life capture, a mesh structure, such as a fishing net, can be completely covered on the outside of each bistable bending spring 11. The mesh structure is fixed to the curved surface of each individual bistable bending spring 11, covering the inner and / or outer surfaces of the bistable bending spring 11, with its edges substantially flush with the edges of the bistable bending spring 11 and not crossing the gaps between the bistable bending springs 11. When the grasping device switches from the extended state to the closed state, the mesh structure covering the outside of each bistable bending spring 11 retracts synchronously with the spring, forming multiple independent flexible barriers within the grasping space, restricting the movement of captured organisms, and further improving the grasping success rate. The mesh structure can be selected with different mesh sizes according to the size of the target organism. Since it adopts the method of independent application of single elastic pieces, it does not affect the mechanical properties and flipping performance of the bistable bending elastic piece 11 itself, nor does it interfere with the relative movement between each bistable bending elastic piece 11. At the same time, it avoids the generation of redundant wrinkles or additional fluid resistance in the unfolded state of the mesh structure.

[0050] During operation, the gripping device is initially in the deployed state (e.g., Figure 2 (As shown). When gripping is required, the micro servo motor 21 drives the central drive component 23 to move via the servo disk 22. The central drive component 23 pushes the connecting rod 25 to slide radially along the linear guide groove 241 of the lower limiting plate 24, while simultaneously pushing the root of each bistable actuator 1, causing the bistable bending spring 11 to cross the potential barrier and quickly flip from the unfolded configuration to the closed configuration (as shown). Figure 1 As shown), the grasping action is completed. Due to the existence of bistable characteristics, the grasping device can stably maintain the closed state without continuous energy input. When it is necessary to release the target, the micro servo motor 21 is reversed, causing the bistable bending spring 11 to flip from the closed configuration back to the unfolded configuration.

[0051] The specific process by which connecting rod 25 pushes the bistable bending spring 11 to cross the barrier is explained as follows: First, the force transmission path is as follows: the micro servo motor 21 drives the central drive component 23 to rotate, and the curved slot 231 on the central drive component 23 drives the connecting rod 25 to move through the cylinder at one end of the connecting rod 25 (this cylinder is, for example, a half-threaded screw, which passes through both the curved slot 231 of the central drive component 23 and the straight guide slot 241 of the lower limiting plate 24); the cylinder at the other end of the connecting rod 25 passes through the hole of the guide component 26 and is directly connected to the root connection interface 14 of the bistable bending spring 11. Therefore, the connecting rod 25 transmits the driving force to the root of the spring by pushing / pulling the root connection interface 14.

[0052] Secondly, the mechanical process of overcoming the potential barrier is as follows: the bistable bending spring 11 has two stable states (expanded state and closed state), and there is a potential energy peak (potential barrier) between the two states. The process of pushing the bistable bending spring 11 from the expanded state to the closed state is as follows: ① Initial stage (elastic deformation stage): the connecting rod 25 applies a radial thrust F to the root of the bistable bending spring 11 through the root connection interface 14. This force generates a bending moment M=F·L at the root of the spring (L is the lever arm from the point of application of the thrust to the fixed point of the bistable bending spring 11), causing the bistable bending spring 11 to undergo elastic deformation. At this time, the spring begins to deviate from the expanded stable state, and the system potential energy gradually increases. ② Critical point (potential barrier peak): as the thrust continues to increase, the deformation of the bistable bending spring 11 gradually accumulates, and the system potential energy reaches its maximum value (potential barrier peak). At this time, the bistable bending spring 11 is in an unstable equilibrium state, and a small disturbance can trigger a flip. ③ Flipping Stage (Potential Energy Release Stage): When the deformation exceeds the potential barrier apex, the elastic potential energy stored inside the bistable bending spring 11 is released instantaneously, driving the bistable bending spring 11 to quickly flip towards the closed stable state. At this time, even if the external force is removed, the bistable bending spring 11 will automatically complete the flipping and stabilize in the closed state.

[0053] Furthermore, the relationship between the displacement and the trajectory of the end of the spring is as follows: the radial displacement of the root connection interface 14 and the circumferential displacement of the end of the bistable bending spring 11 are nonlinearly related. This nonlinear relationship can be described by the potential energy-displacement curve of the bistable bending spring 11: the potential energy curve has two troughs (steady state) and one peak (potential barrier). The root displacement drives the bistable bending spring 11 to climb from one trough to the peak, and then quickly fall to another trough.

[0054] To verify the response speed of the present invention, multiple grasping experiments were conducted on the prototype. The test results showed that the average time from receiving the control signal to complete closure of the grasping device was 0.58 seconds (580 milliseconds). This response speed has reached the millisecond level, which can meet the response requirements of the grasping mechanism in the dynamic underwater environment.

[0055] The control logic of the gripping device in this embodiment is as follows: the micro servo motor 21 rotates between two fixed angles (0° for unfolding and 90° for closing), and the servo motor is controlled to rotate forward or backward via a PWM signal. The controller only needs to send two fixed PWM signals: one corresponding to the angle of the closed configuration and one corresponding to the angle of the unfolded configuration, and no intermediate position feedback is required. In practical applications, functions such as current detection can also be added to sense abnormal loads and prevent the mechanism from jamming. During gripping, the controller sends the PWM signal corresponding to the angle of the closed configuration, and the servo motor rotates forward to the set angle (e.g., 90°), causing the gripping device to close; during release, the controller sends the PWM signal corresponding to the angle of the unfolded configuration, and the servo motor rotates backward to the set angle (e.g., 0°), causing the gripping device to unfold. By alternately sending two fixed angle signals, the gripping device can be repeatedly activated. Due to its bistable characteristics, the gripping device can maintain itself without continuous power supply after reaching the target state, and the servo motor can be powered off.

[0056] The modular bistable flexible gripping device disclosed in the preferred embodiment of the present invention has the following advantages: (1) Lightweight structure and compact drive system: The present invention uses a bistable bending spring as the gripping execution unit, which eliminates the complex linkage transmission structure in the traditional rigid gripping device; at the same time, it utilizes the bistable characteristics to achieve configuration self-holding, and a rotary iris drive mechanism, which only requires a single servo motor to complete the synchronous and precise excitation of multiple bistable springs, significantly reducing the overall weight and structural complexity of the gripping device, and effectively solving the problem of load-bearing limitation on cross-medium platforms.

[0057] (2) Extremely low energy consumption and strong endurance: Based on the working principle of bistable structure, the present invention only requires energy input at the moment of configuration switching, and does not need continuous power supply during the grasping state maintenance phase, which greatly reduces the overall energy consumption and extends the endurance of the cross-medium robot in underwater operation.

[0058] (3) Fast response speed and high underwater stability: The potential energy reversal mechanism of the bistable structure enables the grasping device to complete the configuration switch from unfolding to closing within a millisecond time window. After multiple experimental tests, the average response time is 0.58 seconds (580 milliseconds), which can meet the stringent requirements of the underwater dynamic environment for the response speed of the grasping mechanism. At the same time, the spring adopts a U-shaped hollow structure design, which effectively reduces the local jet disturbance caused by water compression during the enveloping grasping process, and improves the grasping success rate and target holding stability.

[0059] (4) Modular and reconfigurable with strong task adaptability: The present invention adopts a modular design with independent installation of execution units, which supports the rapid combination and replacement of execution units with different numbers (such as two fingers, four fingers) and different layouts, so that one drive system can adapt to various operation scenarios such as soft biological envelope grasping and sediment clamping grasping, and realize "one machine for multiple uses".

[0060] (5) Non-destructive grasping and target-friendly: The bistable spring forms a flexible envelope space during the closing process, which can adaptively fit the irregular target surface and avoid damage caused by rigid contact. It is particularly suitable for non-destructive collection of underwater biological samples.

[0061] In summary, this invention employs a bistable structure based on the U-shaped spring sheet itself, and directly drives the spring sheet to flip through a rotary iris mechanism to achieve envelope grasping. It eliminates the need for an air source and rope transmission, and has the advantages of lighter structure, lower energy consumption, faster response, and higher modularity. It is particularly suitable for cross-media robot platforms with stringent requirements for load capacity, energy consumption, and response speed.

[0062] Another preferred embodiment of the present invention discloses a sea-air cross-medium robot, which includes a robot body and is equipped with a modular bistable flexible grasping device as described in the preferred embodiment above.

[0063] The sea-air cross-medium robot of this invention has strict requirements on load capacity, energy consumption and response speed. It adopts a pure mechanical + spring self-drive to achieve bistable flexible grasping. Its advantages are: (1) Lighter structure: No need for air pump, air chamber, rope and other components, the weight of the whole machine is greatly reduced; (2) Lower energy consumption: No need for continuous air supply, only power consumption at the moment of servo motor activation; (3) Faster response: Short transmission chain, no pneumatic delay, and millisecond-level grasping can be achieved; (4) Higher modularity: The execution unit can be replaced independently to adapt to multiple operation scenarios; (5) Better underwater adaptability: The U-shaped hollow structure naturally reduces water resistance and avoids disturbance.

[0064] The background section of this invention may include background information about the problems or circumstances surrounding the invention, rather than a description of prior art by others. Therefore, the content included in the background section is not an admission of prior art by the applicant.

[0065] The above description provides a further detailed explanation of the present invention in conjunction with specific / preferred embodiments, and it should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various substitutions or modifications can be made to these described embodiments without departing from the concept of the present invention, and all such substitutions or modifications should be considered within the scope of protection of the present invention. In the description of this specification, the reference to terms such as "an embodiment," "some embodiments," "preferred embodiment," "example," "specific example," or "some examples," etc., indicates that the specific features, structures, materials, or characteristics described in connection with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions 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 suitable manner in one or more embodiments or examples. Furthermore, those skilled in the art can combine and integrate different embodiments or examples and features of different embodiments or examples described in this specification without contradiction. Although the embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions, and modifications can be made herein without departing from the scope defined by the appended claims.

Claims

1. A modular bistable flexible gripping device, characterized in that, It includes a mounting base, an excitation drive unit, and at least two bistable actuation units, wherein, The bistable actuation unit includes a bistable bending spring and a connecting assembly. Each of the bistable bending springs is mounted on the mounting base in a circular array through the connecting assembly. The bistable bending spring has two stable states in its natural state: an unfolded configuration and a closed configuration, and remains in either configuration without continuous energy input. The excitation driving unit includes a driving source and a driving component. The driving source is mounted on the mounting base, and the driving component is connected to the output end of the driving source. The driving component is respectively drivenly connected to the root of each of the bistable bending springs to drive the bistable bending springs to switch between the unfolded configuration and the closed configuration. The excitation driving unit adopts a rotary iris driving mechanism. The driving source drives the driving component to rotate. The driving component drives the root of each bistable bending spring to move in the radial direction, so as to drive the bistable bending spring to switch between the unfolded configuration and the closed configuration. The driving assembly includes a central driving component, a limiting plate, and at least two connecting rods. The output end of the driving source is connected to the central driving component to drive the central driving component to rotate. The limiting plate is mounted on the mounting base. The central driving component has a curved groove, and the limiting plate has radially distributed straight guide grooves. The first end of each connecting rod is simultaneously limited in the curved groove and the straight guide groove, and the second end of each connecting rod is fixedly connected to the root of each bistable bending spring.

2. The modular bistable flexible gripping device according to claim 1, characterized in that, The bistable bending spring is composed of a U-shaped spring base and a spring lock, wherein the two ends of the U-shaped spring base are fastened and fixed by the spring lock.

3. The modular bistable flexible gripping device according to claim 2, characterized in that, The U-shaped spring substrate is made of polypropylene with a thickness of 0.5mm to 1.2mm.

4. The modular bistable flexible gripping device according to claim 1, characterized in that, The mounting base has multiple mounting interfaces along the circumferential direction. The connecting assembly includes a spring clip fixing member and a locking ring. One end of the spring clip fixing member is fixedly connected to the root of the bistable bending spring clip. The other end of the spring clip fixing member has a protruding column. The end of the column is inserted into the mounting interface and passes through the mounting base to be fixedly connected with the locking ring.

5. The modular bistable flexible gripping device according to claim 1, characterized in that, Each of the bistable bending springs has a root connection interface at its root, and the second end of each of the connecting rods is connected to the root connection interface of each of the bistable bending springs.

6. The modular bistable flexible gripping device according to claim 5, characterized in that, The drive assembly further includes at least two guide members, which are fixedly connected to the mounting base or the limiting plate. Guide holes are provided on the guide members, and the second end of each connecting rod passes through the guide hole.

7. The modular bistable flexible gripping device according to claim 1, characterized in that, The bistable actuation unit further includes a mesh barrier, which is attached and fixed to the inner and / or outer side of the bistable bending spring.

8. A sea-air cross-medium robot, characterized in that, It includes a robot body, on which a modular bistable flexible gripping device as described in any one of claims 1 to 7 is mounted.

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