Bionic flagellum actuator based on bacterial flagellum structure and preparation method

Abstract

The invention provides a bionic flagellum actuator based on a bacterial flagellum structure and a preparation method. The bionic flagellum actuator comprises a flexible hook which is of a pre-bent arc-shaped structure, mechanical interfaces with protruding platforms are arranged at the two ends of the flexible hook, and a reinforcing framework is embedded in the flexible hook; the flagellum filament is of a gradient cross section circular truncated cone structure and is composed of a silica gel base body, an internal elastic support and an external woven mesh pipe. The modular interface comprises a hook end flange connecting piece and a driving end quick release buckle; the flexible hooks and the flagellum filaments are mechanically interlocked through the protruding platform to be integrally formed in a casting mode, the woven net pipe restrains radial expansion of the flagellum filaments, and the elastic support induces directional bending deformation. The actuator has high flexibility, high environmental adaptability and easy maintainability, can adapt to different load scenes by adjusting the material hardness, the section gradient and the pre-bending angle, and provides an efficient and low-cost solution for the field of flexible driving.

Description

Technical Field

[0001] The present invention relates to the field of flexible driving, precision operation and bionic propulsion technology, and more specifically, to a bionic flagella actuator based on a bacterial flagella structure and a preparation method thereof. Background Art

[0002] In recent years, the combination of bionics and soft robotics has driven the rapid development of flexible actuators. Traditional rigid actuators rely on multi-joint serial structures to achieve complex movements, and have defects such as high power consumption, poor environmental adaptability, and easy damage to fragile targets. In this context, flexible drive technology inspired by biological flagella has gradually become a research hotspot. Existing soft actuators are mostly driven by pneumatics, hydraulics, or shape memory alloys. For example, pneumatic bending artificial muscles deform by inflation, but their ends often use rigid connection structures, resulting in insufficient flexibility when interacting with the driven object; and one-piece silicone actuators, although highly elastic, have problems such as low tensile strength, easy fatigue fracture, and difficulty in modular replacement. In addition, existing preparation processes (such as direct ink writing and laser sintering) have limited ability to realize complex cross-sectional structures and are expensive, which limits the large-scale application of actuators.

[0003] In terms of material selection, existing studies mostly use single-hardness silicone, which makes it difficult to balance deformation sensitivity and load capacity. For example, although low-hardness silicone (such as Dragon Skin 10) can achieve large deformation, it has poor tear resistance and is prone to failure after long-term use; high-hardness silicone (such as Smooth-Silence 960) has high mechanical strength, but it leads to reduced driving efficiency. In terms of structural design, most actuators use a cylindrical or flat plate shape with a uniform cross-section, which cannot simulate the gradient mechanical properties of biological flagella, resulting in uneven stress distribution during movement, which is prone to local deformation loss or energy loss.

[0004] To address the above problems, there is an urgent need for a bionic flagellar actuator that is highly elastic, fatigue-resistant, and easy to maintain. The driving efficiency can be improved through structural innovation and material optimization, and a high-precision dynamic model can be established to guide design and control. Summary of the Invention

[0005] In response to the technical problems raised above, a bionic flagellar actuator based on the structure of bacterial flagella and a preparation method are provided. Based on the biomimetic principles of bacterial flagella, this invention designs a bionic flagellar actuator that combines high elasticity, fatigue resistance, and modularity. This actuator achieves efficient actuation and precise control through a gradient cross-section structure, material optimization, and dynamic modeling.

[0006] The technical means adopted in the present invention are as follows:

[0007] A bionic flagella actuator based on a bacterial flagella structure, comprising:

[0008] The flexible hook adopts a pre-bent arc structure, with mechanical interfaces with protruding platforms at both ends and a reinforced skeleton embedded inside;

[0009] The flagellar filament is a truncated cone-shaped structure with a gradient cross section, consisting of a silicone matrix, an internal elastic support, and an external braided mesh tube;

[0010] Modular interface, including hook-end flange connector and drive-end quick-release buckle, supports rapid actuator replacement and multi-degree-of-freedom assembly;

[0011] The flexible hook and the flagellar filament are mechanically interlocked and integrally cast through the protrusion platform. The braided mesh tube constrains the radial expansion of the flagellar filament, and the elastic bracket induces directional bending deformation.

[0012] Furthermore, the pre-bending angle of the flexible hook is 30°-60°, the arc length is 50-80 mm, the internal reinforcement skeleton is stainless steel wire, and a mechanical interlocking is formed with the silicone matrix through the protruding platform to prevent dislocation under high-speed driving.

[0013] Furthermore, the gradient cross-section of the flagellar filament satisfies the upper base radius of 1-2 mm, the lower base radius of 20-25 mm, and the height of 200-300 mm, and the cross-sectional area decays exponentially along the axial direction to match the mechanical distribution characteristics of biological flagella.

[0014] Furthermore, the silicone matrix is ​​Dragon Skin 30 or Smooth-Silence 936 material, and the hardness and tear strength are controlled by adjusting the A / B component ratio. The hardness is Shore A30-60 and the tear strength is 108-115pli.

[0015] Furthermore, the elastic support is asymmetrically distributed along the axial direction of the flagellar filament, limiting unilateral tensile deformation to induce bending. A polyurethane material is selected, and the Young's modulus is 5-10 times that of the silicone matrix. It is asymmetrically embedded in the flagellar filament in a pre-compressed state, generating a nonlinear restoring force during the driving process, thereby improving the controllability of deformation.

[0016] Furthermore, the braided mesh tube is made of nylon fibers wound at a 60° crossing angle to restrict radial expansion and enhance tensile strength. The fiber spacing decreases along the axial direction, and the density at the end is 3-5 times that of the root to balance the gradient requirements of bending stiffness and tensile strength.

[0017] Furthermore, the driving end of the modular interface is provided with a magnetic positioning pin and a multi-stage sealing ring, the coaxiality error is less than 0.1 mm, and fluid infiltration is prevented.

[0018] Furthermore, the dynamic model of the bionic flagellar actuator describes the actuator posture transformation through Lie group Lie algebra, and establishes the strain-stress-external load equilibrium equation, which specifically includes:

[0019] Define the arc length parameter s and time t, and convert the three-dimensional deformation into a six-dimensional velocity spinor through antisymmetric mapping;

[0020] The hyperelastic constitutive relation of silicone material is introduced to calculate the nonlinear strain energy density;

[0021] Couple the fluid resistance matrix to solve the mapping relationship between dynamic deformation and propulsion force.

[0022] The present invention also provides a method for preparing the above-mentioned bionic flagella actuator based on the bacterial flagella structure, comprising:

[0023] S1. Design and 3D print hook and flagellar filament molds, including:

[0024] S11. Use SOLIDWORKS software to construct a separate mold for the hook and flagellar filament. The hook mold contains an arc-shaped cavity and a protruding platform inlay groove. The flagellar filament mold is a two-piece frustum-shaped structure with an observation hole and a demoulding slot at the end.

[0025] S12. Select light-curing resin (R4600) to print the mold. The surface roughness of the hook mold is Ra ≤ 3.2 μm, and the inner wall of the flagellar mold is polished to Ra ≤ 1.6 μm.

[0026] S13. Design a boss and groove with a width of 5mm and a height of 3mm on the mold contact surface, with a fit tolerance of H7 / g6, and fasten them with M3 bolts;

[0027] S2. Preparation and casting of a silica gel matrix, specifically including:

[0028] S21. Mix the silicone components in a weight ratio of 1A:1B (Dragon Skin 30) or 10A:1B (Smooth-Silence 936) and weigh using a high-precision electronic scale (±0.1g accuracy).

[0029] S22, placing the mixed colloid in a vacuum degassing machine and degassing at a pressure of -0.1 MPa for 10-15 minutes until no bubbles are visible;

[0030] S23, evenly apply vaseline release agent on the inner wall of the mold, assemble the split mold and pre-fix the elastic bracket and the braided mesh tube;

[0031] S24, tilt the silicone injection until it overflows the observation hole, let it stand and cure for 16-24 hours, trim the burrs after demoulding and perform secondary curing for 6 hours;

[0032] S3. Assemble the actuator and perform performance testing, including:

[0033] S31, embed the hook and the flagellar filament through the protrusion platform, apply a preload of 5-10N and cure for 24 hours;

[0034] S32. Install the modular interface and tighten the flange bolts using a torque wrench (0.5-2 N·m);

[0035] S33. Test the tensile strength (≥500 psi) and fatigue life (10^6 cycles of deformation attenuation ≤15%) using a tensile testing machine;

[0036] S34, based on laser displacement sensor and high-speed camera to collect bending angle (≥90°), torsional stiffness (0.1-0.3N·m / rad) and response time (≤0.5s);

[0037] S35, no-load test, apply a 0.1-0.5Hz sinusoidal drive signal, and record the deformation hysteresis angle (≤5°) and resonant frequency (≥10Hz);

[0038] S36, load test, hang 0.1-1kg weight, measure the end displacement attenuation rate (≤20%) and creep amount (≤5% initial deformation).

[0039] Furthermore, in step S22, the volume of the colloid after vacuum degassing does not exceed 50% of the container capacity, the curing temperature is controlled at 20-25°C, and the humidity is ≤60%.

[0040] Compared with the prior art, the present invention has the following advantages:

[0041] 1. The present invention provides a bionic flagella actuator based on the bacterial flagella structure, which has high flexibility, strong environmental adaptability and easy maintenance. It can adapt to different load scenarios by adjusting the material hardness, cross-sectional gradient and pre-bending angle, providing an efficient and low-cost solution for the field of flexible drive.

[0042] 2. The present invention provides a bionic flagella actuator based on the bacterial flagella structure, which optimizes stress distribution through gradient cross-section and braided mesh tube design, and its tensile strength is increased by more than 40% compared with the actuator with uniform cross-section.

[0043] 3. The present invention provides a bionic flagella actuator based on the bacterial flagella structure. The modular interface supports rapid replacement and multi-scenario adaptation, reducing maintenance costs by 60%.

[0044] 4. The present invention provides a bionic flagella actuator based on the bacterial flagella structure. The dynamic model prediction accuracy based on Cosserat rod theory reaches 90%, which can guide parametric drive control.

[0045] 5. The present invention provides a bionic flagella actuator based on the bacterial flagella structure. The split casting process takes into account both complex structure and surface smoothness, and the yield rate is increased to more than 95%.

[0046] In summary, the present invention solves the problems of weak driving force, short life, and rough modeling of existing flexible actuators through bionic structural innovation, material composite and high-precision modeling. It can be widely used in medical robots, underwater grasping and bionic propulsion fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0048] Figure 1 Schematic diagram of the overall structure of the bionic flagella actuator of the present invention.

[0049] Figure 2 Schematic diagram of the split mold and casting process of the present invention.

[0050] Figure 3 This is the Cosserat rod theoretical modeling and simulation results of the present invention.

[0051] In the figure: 1. Hook; 2. Flagellar filament; 3. Glue injection port; 4. Observation hole. DETAILED DESCRIPTION

[0052] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0053] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0054] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0055] Unless otherwise specified, the relative arrangement of the parts and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be clear that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to actual proportional relationships. The technology, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be considered as a part of the specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of the exemplary embodiments can have different values. It should be noted that similar numbers and letters represent similar items in the following drawings, and therefore, once an item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0056] In the description of the present invention, it should be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "horizontal, vertical, vertical, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention: the directional words "inside and outside" refer to the inside and outside relative to the outline of each component itself.

[0057] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used herein to describe the spatial positional relationship of a device or feature to other devices or features as shown in the figures. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figures. For example, if the device in the drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below their position devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0058] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0059] like Figure 1 As shown, the present invention provides a bionic flagella actuator based on a bacterial flagella structure, comprising:

[0060] The flexible hook adopts a pre-bent arc structure, with mechanical interfaces with protruding platforms at both ends and a reinforced skeleton embedded inside;

[0061] The flagellar filament is a truncated cone-shaped structure with a gradient cross section, consisting of a silicone matrix, an internal elastic support, and an external braided mesh tube;

[0062] Modular interface, including hook-end flange connector and drive-end quick-release buckle, supports rapid actuator replacement and multi-degree-of-freedom assembly;

[0063] The flexible hook and the flagellar filament are mechanically interlocked and integrally cast through the protrusion platform. The braided mesh tube constrains the radial expansion of the flagellar filament, and the elastic bracket induces directional bending deformation.

[0064] During specific implementation, as a preferred embodiment of the present invention, the pre-bending angle of the flexible hook is 30°-60°, the arc length is 50-80mm, the internal reinforcement skeleton is stainless steel wire, and a mechanical interlock is formed with the silicone matrix through the protrusion platform to prevent dislocation under high-speed drive. In this embodiment, the hook body of the flexible hook adopts a pre-bent arc structure, the arc length is set to 50mm, the pre-bending angle is 45°, the bending radius is 30mm, and the arc curvature is optimized by the cubic spline function to ensure that the stress concentration coefficient is ≤1.5. The two ends of the flexible hook are designed as trapezoidal protrusion platform mechanical interfaces, the platform size is 10mm long and 5mm wide × 3mm high, the spacing between adjacent protrusions is 2mm, and the platform surface is processed with M3 threaded holes (depth 5mm, distance 0.5mm) for rigid connection with the flagellar filaments. A 304 stainless steel wire skeleton with a diameter of 1mm is embedded in the hook body of the flexible hook, asymmetrically distributed along the arc centerline (offset 2mm), and the end extends to 5mm from the protrusion platform and is fixed by laser welding.

[0065] In specific implementation, as a preferred embodiment of the present invention, the gradient cross-section of the flagellar filament satisfies the upper base radius of 1-2mm, the lower base radius of 20-25mm, and the height of 200-300mm, and the cross-sectional area decays along the axial direction according to an exponential function to match the mechanical distribution characteristics of biological flagella. In this embodiment, the flagellar filament has a truncated cone-shaped gradient cross-section with the following geometric parameters: upper radius of 1mm, lower base radius of 25mm, height of 300mm, and cross-sectional area decays along the axial direction according to an exponential function (reduction coefficient k = 0.02mm -1 The mold is divided into two parts, the inner wall is diamond polished to Ra ≤ 1.6μm, a rectangular observation hole with a diameter of 2mm is set at the end, and a tapered injection port is designed at the bottom (inclination angle 15°, straight 8mm).

[0066] In a preferred embodiment of the present invention, the silicone substrate is Dragon Skin 30 or Smooth-Silence 936. Hardness and tear strength are controlled by adjusting the A / B ratio, resulting in a hardness of 30-60 Shore A and a tear strength of 108-115 pli. In this example, Smooth-Silence 936 (36 Shore A, 650 psi tensile strength) is used as the silicone substrate, with an A:B ratio of 10:1. 0.5 wt% carbon black powder (20 nm particle size) is added to enhance UV resistance.

[0067] During specific implementation, as a preferred embodiment of the present invention, the elastic support is asymmetrically distributed along the axial direction of the flagellar filament, limiting unilateral tensile deformation to induce bending. A polyurethane material with a Young's modulus 5-10 times that of a silicone matrix is ​​selected. The elastic support is asymmetrically embedded in the flagellar filament in a pre-compressed state, generating a nonlinear restoring force during the actuation process, thereby improving the controllability of deformation. In this embodiment, the elastic support is a polyurethane rod (diameter 2mm, Young's modulus 1.2GPa, elongation at break 350%), offset 2mm along the axis of the flagellar filament, and pre-compressed by 5% at both ends using a 3D printing fixture (material PLA).

[0068] In practice, as a preferred embodiment of the present invention, the braided mesh tube is made of nylon fibers wound at a 60° cross angle to constrain radial expansion and enhance tensile strength. The fiber spacing decreases axially, and the density at the end is 3-5 times that at the root to balance the gradient requirements of bending stiffness and tensile strength. In this embodiment, the braided mesh tube uses nylon 66 fibers (diameter 0.2mm, tensile strength 800MPa), wound at a 60° cross angle, with the density in the end area increased to 30 fibers / cm (10 fibers / cm at the root), and the braiding tension is controlled to 0.5-1.0N.

[0069] In specific implementation, as a preferred embodiment of the present invention, the drive end of the modular interface is equipped with a magnetic locating pin and a multi-stage sealing ring, with a coaxial error of less than 0.1mm and preventing fluid infiltration. In this embodiment, the hook end connection: a stainless steel bolt (strength grade 8.8, torque 1.2N·m) is installed in the M3 threaded hole of the hook protrusion platform. The bolt head is embedded 3mm into the silicone matrix. The gap is filled with epoxy resin glue (3M DP420, mixing ratio 10:1), and the curing condition is 24 hours (temperature 25°C). The connection is tensile tested (load 0-100N) to ensure that the interface tensile strength is ≥200N and the displacement is ≤0.5mm. The drive end interface: The drive end flange is machined from aluminum alloy 6061 (tensile strength 310MPa), with an inner diameter of 12mm (tolerance H7) and an outer diameter of 25mm. Three evenly spaced M4 threaded holes (depth 8mm) are opened on the end face. The flange is bonded to the end of the flagellar filament via a vulcanization process: vulcanization temperature: 150°C, pressure: 2 MPa, time: 30 minutes. The adhesive used is silicone rubber RTV-118 (shear strength: 2.5 MPa). A neodymium iron boron magnet (grade N52, 3 mm diameter x 1 mm thickness) is embedded in the flange end face and mates with a magnetic locating pin (3 mm diameter x 5 mm length) on the motor shaft. The coaxiality error is ≤ 0.08 mm (measured using a coordinate measuring machine).

[0070] In specific implementation, as a preferred embodiment of the present invention, the dynamic model of the bionic flagella actuator describes the actuator posture transformation through Lie group Lie algebra, and establishes the strain-stress-external load balance equation, which specifically includes:

[0071] Define the arc length parameter s and time t, and convert the three-dimensional deformation into a six-dimensional velocity spinor through antisymmetric mapping;

[0072] The hyperelastic constitutive relation of silicone material is introduced to calculate the nonlinear strain energy density;

[0073] Couple the fluid resistance matrix to solve the mapping relationship between dynamic deformation and propulsion force.

[0074] In this embodiment, the dynamic behavior of the actuator is modeled using the Cosserat rod theory, including:

[0075] Parameter definition:

[0076] Geometric description: including arc length s∈[0,300mm] and pose transformation matrix g(s,t)=[R(s,t),p(s,t)]∈SE(3);

[0077] Strain vector: including ξ(s,t)=[ε x ,ε y ,ε z ,κ x ,κ y ,κ z ] T and reference strain ξ0=[0,0,0,0,0,0] T .

[0078] Equilibrium equations: including internal force balance, momentum balance and constitutive relations, in order:

[0079]

[0080] n=K s (ξ-ξ0), m=K b (ξ-ξ0)

[0081] Among them, K s =diag(EA,GA,GA),K b =diag(GJ,EI,EI);

[0082] Numerical solution:

[0083] Discretization: 10 cells, spatial step Δs = 30 mm, time step Δt = 0.001 s;

[0084] Boundary conditions: the driving end is fixed (p(0,t)=0, R(0,t)=I), and there is no external force on the free end (n(L,t)=0, m(L,t)=0);

[0085] Simulation results (such as Figure 3 shown):

[0086] Deformation response: Under 10Hz sinusoidal drive, the end bending angle is 92.3° (measured error ≤ 2%);

[0087] Mechanical properties: Steady-state propulsion force 0.85N, power consumption 2.1W, efficiency 40.5%;

[0088] Stress distribution: Maximum Von Mises stress is 2.1 MPa (hook connection), which is lower than the yield strength of silicone (4.5 MPa);

[0089] The present invention also provides a method for preparing the above-mentioned bionic flagella actuator based on the bacterial flagella structure, comprising:

[0090] S1. Design and 3D print hook and flagellar filament molds, including:

[0091] S11. Use SOLIDWORKS software to construct a separate mold for the hook and flagellar filament. The hook mold contains an arc-shaped cavity and a protruding platform inlay groove. The flagellar filament mold is a two-piece frustum-shaped structure with an observation hole and a demoulding slot at the end.

[0092] S12. Select light-curing resin (R4600) to print the mold. The surface roughness of the hook mold is Ra ≤ 3.2 μm, and the inner wall of the flagellar mold is polished to Ra ≤ 1.6 μm.

[0093] S13. Design a boss and groove with a width of 5mm and a height of 3mm on the mold contact surface, with a fit tolerance of H7 / g6, and fasten them with M3 bolts;

[0094] In this embodiment, if Figure 2 As shown, the three-dimensional model of the hook mold is established using SOLIDWORKS2022 software. The mold is divided into two pieces, the upper and lower parts. The contact surface is set with grooves and bosses with a width of 5.3mm and a depth of 3.2mm, and the matching tolerance is H7 / g6. The light-curing resin R4600 (tensile strength 50MPa, elongation at break 8%) is selected to print the mold. The printing layer thickness is 0.05mm, the UV intensity is 15mW / cm2, and after printing, it is ultrasonically cleaned with ethanol for 10 minutes (frequency 40kHz) and post-cured in a 60°C oven for 2 hours. The inner surface of the mold cavity is sprayed with a polytetrafluoroethylene coating (thickness 10μm) to reduce the demoulding resistance, and the surface roughness Ra≤3.2μm.

[0095] The flagellar filament mold consists of two halves, the inner wall of which is diamond-polished to Ra ≤ 1.6 μm. A 2 mm diameter rectangular observation hole is located at the end, and a tapered injection port (15° tilt, 8 mm vertical) is designed at the bottom. Using a layered casting process, the lower half of the mold is first mounted horizontally on a vibrating platform (0.1 mm amplitude, 10 Hz frequency). A braided mesh tube is then laid, and an elastic support is secured with a clamp. Then, 50% by volume of silicone rubber (25°C) is injected. The mold is tilted 30° to allow the gel to flow to the observation hole at the end, and the mold is allowed to stand for 10 minutes to eliminate flow marks. The remaining silicone rubber is then injected, covering the elastic support and mesh tube. After closing the mold, a pressure of 0.5 MPa (holding time 5 minutes) is applied, and the mold is cured for 36 hours (25°C, humidity ≤ 60%). Finally, the mold is demolded and placed in a thermostat for a secondary cure of 12 hours (60°C). Finally, the surface is polished using 800 grit sandpaper.

[0096] S2. Preparation and casting of a silica gel matrix, specifically including:

[0097] S21. Mix the silicone components in a weight ratio of 1A:1B (Dragon Skin 30) or 10A:1B (Smooth-Silence 936) and weigh using a high-precision electronic scale (±0.1g accuracy).

[0098] S22, placing the mixed colloid in a vacuum degassing machine and degassing at a pressure of -0.1 MPa for 10-15 minutes until no bubbles are visible;

[0099] S23, evenly apply vaseline release agent on the inner wall of the mold, assemble the split mold and pre-fix the elastic bracket and the braided mesh tube;

[0100] S24, tilt the silicone injection until it overflows the observation hole, let it stand and cure for 16-24 hours, trim the burrs after demoulding and perform secondary curing for 6 hours;

[0101] In this embodiment, Dragon Skin 30 silicone rubber was mixed in a ratio of A:B = 1:1 (weight ratio), stirred at 300 rpm for 5 minutes, and vacuum degassing was performed at -0.095 MPa for 15 minutes until no bubbles (diameter > 0.2 mm) were visible in the colloid. Vaseline release agent (thickness 0.1 mm) was evenly applied to the inner wall of the mold, and silicone rubber was injected after pre-fixing the stainless steel wire skeleton. The mold was allowed to cure for 24 hours (temperature 25 ± 2 ° C, humidity 50 ± 5%). After demolding, the flash was trimmed using a precision blade (blade angle 30°), and an M3 threaded hole (tapping torque 0.8 N·m) was machined on the surface of the hook protrusion platform.

[0102] S3. Assemble the actuator and perform performance testing, including:

[0103] S31, embed the hook and the flagellar filament through the protrusion platform, apply a preload of 5-10N and cure for 24 hours;

[0104] S32. Install the modular interface and tighten the flange bolts using a torque wrench (0.5-2 N·m);

[0105] S33. Test the tensile strength (≥500 psi) and fatigue life (10^6 cycles of deformation attenuation ≤15%) using a tensile testing machine;

[0106] S34, based on laser displacement sensor and high-speed camera to collect bending angle (≥90°), torsional stiffness (0.1-0.3N·m / rad) and response time (≤0.5s);

[0107] S35, no-load test, apply a 0.1-0.5Hz sinusoidal drive signal, and record the deformation hysteresis angle (≤5°) and resonant frequency (≥10Hz);

[0108] S36, load test, hang 0.1-1kg weight, measure the end displacement attenuation rate (≤20%) and creep amount (≤5% initial deformation).

[0109] Example 1 (Performance Test and Comparison)

[0110] Mechanical properties testing

[0111] Tensile test (ASTM D412 standard): tensile strength 650 psi (38% increase compared to the actuator with uniform cross-section), elongation at break 420%; elastic modulus 0.58 MPa (linear range 0-300% strain).

[0112] Fatigue life test (ISO 6943 standard): 10 6 After the second cycle, the deformation attenuation rate is 12.7% and there is no delamination at the interface.

[0113] Dynamic response test

[0114] Bending performance: rise time 0.42s, overshoot ≤5%, steady-state error ±1.5mm (repeatability σ=0.3mm);

[0115] Torsional stiffness: Torsional stiffness 0.25 N·m / rad (linearity R2=0.993), hysteresis loop area ≤3%.

[0116] Environmental adaptability test

[0117] Temperature cycle (-20℃~60℃): tensile strength attenuation rate ≤3%;

[0118] Medium resistance (artificial seawater, hydraulic oil): volume expansion rate ≤1.5%, hardness change ΔShore A ≤2.

[0119] Example 2 (Variable Parameter Optimization and Application)

[0120] Pre-bend angle optimization:

[0121] Design variables: hook pre-bend angle θ = 30°, 45°, 60°, and arc length fixed at 50 mm;

[0122] Test results: When θ = 45°, the end bending angle is the largest (92.3°) and the energy efficiency is the highest (42.1%); when θ = 60°, the propulsion force is increased to 0.92N, but the response time is extended to 0.55s.

[0123] Braided network tube density gradient adjustment:

[0124] Plan: Root density 10 roots / cm, middle 20 roots / cm, end 30 roots / cm;

[0125] Results: The tensile strength was increased to 720 psi (uniform density group: 650 psi); the bending stiffness gradient was matched, and the controllability of the terminal deformation was improved by 15%.

[0126] Example 3 (Material Replacement)

[0127] Silicone is replaced with Ecoflex 00-30 (Shore A hardness 28, tensile strength 200 psi): suitable for low-load precision operations (such as medical clamping), the bending angle is increased to 110°, but the fatigue life is reduced to 5×10 5 Second-rate.

[0128] The elastic bracket is replaced with a carbon fiber rod (diameter 1.5 mm, Young's modulus 200 GPa): the torsional stiffness is increased to 0.35 N·m / rad, which is suitable for high-frequency drive (≥20 Hz).

[0129] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A bionic flagella actuator based on bacterial flagella structure, characterized in that: include: The flexible hook adopts a pre-bent arc structure, with mechanical interfaces with protruding platforms at both ends and a reinforced skeleton embedded inside; The flagellar filament is a truncated cone-shaped structure with a gradient cross section, consisting of a silicone matrix, an internal elastic support, and an external braided mesh tube; Modular interface, including hook-end flange connector and drive-end quick-release buckle; The flexible hook and the flagellar filament are mechanically interlocked and integrally cast through the protrusion platform. The braided mesh tube constrains the radial expansion of the flagellar filament, and the elastic bracket induces directional bending deformation.

2. A bionic flagella actuator based on bacterial flagella structure according to claim 1, characterized in that: The flexible hook has a pre-bending angle of 30°-60° and an arc length of 50-80 mm. The internal reinforcement skeleton is made of stainless steel wire, and mechanical interlocking is formed with the silicone matrix through the protruding platform.

3. The bionic flagella actuator based on bacterial flagella structure according to claim 1, characterized in that: The gradient cross section of the flagellar filament satisfies the following conditions: an upper base radius of 1-2 mm, a lower base radius of 20-25 mm, and a height of 200-300 mm, and the cross section area decays along the axial direction according to an exponential function.

4. The bionic flagella actuator based on bacterial flagella structure according to claim 1, characterized in that: The silicone matrix is ​​Dragon Skin 30 or Smooth-Silence 936 material. The hardness and tear strength are controlled by adjusting the A / B component ratio. The hardness is Shore A30-60 and the tear strength is 108-115 pli.

5. The bionic flagella actuator based on bacterial flagella structure according to claim 1, characterized in that: The elastic support is asymmetrically distributed along the axial direction of the flagellar filament to limit unilateral tensile deformation to induce bending. The polyurethane material is selected, and the Young's modulus is 5-10 times that of the silicone matrix. It is asymmetrically embedded in the flagellar filament in a pre-compressed state.

6. The bionic flagella actuator based on bacterial flagella structure according to claim 1, characterized in that: The braided mesh tube is wound with nylon fibers at a cross angle to restrict radial expansion and enhance tensile strength. The fiber spacing decreases along the axial direction, and the density at the end is 3-5 times that of the root.

7. The bionic flagella actuator based on bacterial flagella structure according to claim 1, characterized in that: The driving end of the modular interface is provided with a magnetic positioning pin and a multi-stage sealing ring, and the coaxiality error is less than 0.1 mm.

8. The bionic flagella actuator based on bacterial flagella structure according to claim 1, characterized in that: The dynamic model of the bionic flagellar actuator describes the actuator posture transformation through Lie group Lie algebra and establishes the strain-stress-external load balance equation, which specifically includes: Define the arc length parameter s and time t, and convert the three-dimensional deformation into a six-dimensional velocity spinor through antisymmetric mapping; The hyperelastic constitutive relation of silicone material is introduced to calculate the nonlinear strain energy density; Couple the fluid resistance matrix to solve the mapping relationship between dynamic deformation and propulsion force.

9. A method for preparing a bionic flagella actuator based on a bacterial flagella structure according to any one of claims 1 to 8, characterized in that: include: S1. Design and 3D print hook and flagellar filament molds, including: S11. Use SOLIDWORKS software to construct a separate mold for the hook and flagellar filament. The hook mold contains an arc-shaped cavity and a protruding platform inlay groove. The flagellar filament mold is a two-piece frustum-shaped structure with an observation hole and a demoulding slot at the end. S12. Use a light-curing resin to print the mold. The surface roughness of the hook mold is Ra ≤ 3.2 μm, and the inner wall of the flagellar filament mold is polished to Ra ≤ 1.6 μm. S13. Design a boss and groove with a width of 5mm and a height of 3mm on the mold contact surface, with a fit tolerance of H7 / g6, and fasten them with M3 bolts; S2. Preparation and casting of a silica gel matrix, specifically including: S21. Mix the silica gel components in a weight ratio of 1A:1B or 10A:1B and weigh using a high-precision electronic scale; S22, placing the mixed colloid in a vacuum degassing machine and degassing at a pressure of -0.1 MPa for 10-15 minutes until no bubbles are visible; S23, evenly apply vaseline release agent on the inner wall of the mold, assemble the split mold and pre-fix the elastic bracket and the braided mesh tube; S24, tilt the silicone injection until it overflows the observation hole, let it stand and cure for 16-24 hours, trim the burrs after demoulding and perform secondary curing for 6 hours; S3. Assemble the actuator and perform performance testing, including: S31, embed the hook and the flagellar filament through the protrusion platform, apply a preload of 5-10N and cure for 24 hours; S32. Install the modular interface and tighten the flange bolts using a torque wrench. S33. Testing the tensile strength and fatigue life using a tensile testing machine; S34, collecting bending angle, torsional stiffness and response time based on laser displacement sensor and high-speed camera; S35, no-load test, apply a 0.1-0.5Hz sinusoidal drive signal, and record the deformation hysteresis angle and resonant frequency; S36, load test, hang 0.1-1kg weight, measure the end displacement attenuation rate and creep amount.

10. The method for preparing a bionic flagella actuator based on a bacterial flagella structure according to claim 9, characterized in that: In step S22, the volume of the colloid after vacuum degassing does not exceed 50% of the container capacity, the curing temperature is controlled at 20-25°C, and the humidity is ≤60%.

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