Underwater bionic flexible actuator based on electrostatic hydraulic drive

Abstract

The application relates to an underwater bionic flexible actuator based on electrostatic hydraulic driving, which comprises a driving module, a pitching control module and a power supply module; the pitching control module is arranged on the driving module, and the power supply module is connected with the driving module and the pitching control module respectively; the driving module is used for realizing the forward movement of the actuator, and the driving module comprises a flexible undulating fin, two side hardened layers, an elastic hinge layer, a first intermediate hardened layer and a first hydraulic amplification self-healing driver; the pitching control module is used for realizing the floating movement and the sinking movement of the actuator, and the pitching control module comprises a second intermediate hardened layer, a pitching unit and a second hydraulic amplification self-healing driver. Compared with the prior art, the application can realize effective multidirectional swimming through simple preparation and control of the modules; the specific flexible material and the flexible structure have elasticity and chemical resistance.

Description

Technical Field

[0001] This invention relates to the field of soft actuators, and in particular to an underwater biomimetic flexible actuator based on electrostatic hydraulic drive. Background Technology

[0002] Traditional actuators are primarily composed of rigid components, offering high rigidity, powerful motion, and precision. However, they have limitations and shortcomings in certain applications, potentially generating significant vibration, noise, and impact during operation, and failing to effectively mimic the muscular and skeletal systems of living organisms. In recent years, biomimetic flexible actuators, designed by imitating the structure and movement principles of biological organisms, have emerged, bringing numerous new opportunities and attracting widespread attention as a novel actuation technology. Compared to traditional actuators constructed with rigid materials, biomimetic flexible actuators utilize flexible materials and structures, mimicking the muscular and skeletal systems of living organisms, exhibiting superior flexibility, deformability, and adaptability. These actuators can better reduce vibration and noise generation, achieving more natural and efficient movement and manipulation. Existing biomimetic flexible actuators are mostly based on shape memory alloy actuators and pneumatic actuators, which suffer from environmental sensitivity, high energy consumption, complex control, and slow response speeds, significantly reducing their expected effectiveness in soft robotics and related fields. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the existing technology by providing an underwater biomimetic flexible actuator based on electrostatic hydraulic drive, which has excellent driving performance and can achieve multi-stage parallel operation. Effective multi-directional swimming can be achieved through simple module fabrication and control. Utilizing specific flexible materials and structures, it possesses elasticity and chemical resistance; furthermore, the use of a pre-stretched elastic hinge layer provides elastic restoring force, maximizing energy utilization.

[0004] The objective of this invention can be achieved through the following technical solutions: This invention proposes an underwater biomimetic flexible actuator based on electrostatic hydraulic drive. By applying selective constraints through different types of hydraulically amplified self-healing actuators, multi-directional movement of the actuator is achieved. It can be applied in underwater exploration, underwater development, underwater biomimetic robots, water quality testing, and other technical fields. Multi-directional movement is achieved by coordinating the hydraulically amplified self-healing actuators in the drive module and pitch control module with other mechanisms to realize the actuator's forward, upward, and downward movements.

[0005] This invention provides an underwater biomimetic flexible actuator based on electrostatic hydraulic drive, comprising a drive module, a pitch control module, and a power supply module; the pitch control module is mounted on the drive module, and the power supply module is connected to both the drive module and the pitch control module. The drive module is used to propel the actuator forward. The drive module includes: a flexible undulating fin, two hardened layers on both sides, an elastic hinge layer, a first intermediate hardened layer, and a first hydraulically amplified self-healing actuator. The flexible undulating fin is connected to the two hardened layers on both sides. The first hydraulically amplified self-healing actuator is adhered to the first intermediate hardened layer. The elastic hinge layer is symmetrically adhered to the underside of the first intermediate hardened layer and is in a pre-stretched state. The first intermediate hardened layer and the two hardened layers on both sides are hinged together by the elastic hinge layer. The elastic hinge layer provides elastic restoring force for the bent joint. After bending at the joint between the two hardened layers and the first intermediate hardened layer, due to hydrostatic pressure, the joint may not recover in time or fully. The elastic hinge layer provides a certain amount of elastic restoring force, which can reduce the occurrence of untimely or incomplete recovery to some extent.

[0006] The pitch control module is used to realize the upward and downward movement of the actuator. The pitch control module includes: a second intermediate hardened layer, a pitch unit, and a second hydraulic amplification self-healing actuator. The pitch unit and the second hydraulic amplification self-healing actuator are both installed on the second intermediate hardened layer. There are two sets of the second hydraulic amplification self-healing actuator, which are respectively located at the front end and the rear end of the second intermediate hardened layer. When the second hydraulic amplification self-healing actuator at the front end or the rear end is energized, the end of the second hydraulic amplification self-healing actuator near the pitch unit will arch up, changing the tilt degree of the base of the pitch unit, thereby causing the actuator to float or sink.

[0007] The power supply module includes an STM32 microcontroller, a small high-voltage driver board, and an optocoupler. The STM32 microcontroller controls the voltage and frequency of the small high-voltage driver board in real time, and the optocoupler and resistor discharge residual charge, thus controlling the voltage output of the driver module and the pitch control module.

[0008] Furthermore, the first hydraulic amplification self-healing actuator is bag-shaped, with its interior forming a first cavity. The first hydraulic amplification self-healing actuator facilitates adhesion to the hardened layer and provides selective constraint. It is made of a first polyethylene film and a first double-sided conductive adhesive tape, which includes a positive conductive tape and a negative conductive tape, possessing a certain degree of elasticity and flexibility. The first cavity of the first hydraulic amplification self-healing actuator is uniformly filled with a liquid dielectric. The first hydraulic amplification self-healing actuator is symmetrically attached to the opposite side of the elastic hinge layer using cloth-based double-sided adhesive tape, used to drive the hardened layers on both sides to swing, thereby driving the flexible oscillating fin.

[0009] The first hydraulic amplification self-healing actuator has a flat structure under normal conditions. When the two skirts of the first double-sided conductive adhesive tape are energized, the tape gradually adheres due to Maxwell stress, pumping liquid and causing the area without the tape to arch, thus causing the joint to bend. After de-energization, the liquid flows back, evenly filling the first cavity, and the hardened layers on both sides return to their initial positions. Cyclic energization and de-energization can cause the hardened layers on both sides and the flexible oscillating fin to swing back and forth, thereby realizing the forward movement of the actuator.

[0010] In the initial state, the first hydraulic amplification self-healing actuator has no current flowing through the first double-sided conductive tape. The first bag cavity is filled with a uniform liquid dielectric. The joints of the first intermediate hardened layer and the two side hardened layers are in a horizontal state, and the elastic hinge layer is in a pre-stretched state. At this time, the arc length of the first polyethylene film surface is L + ΔL0. When a DC voltage on the order of kilovolts is applied to the first double-sided conductive tape, the positive conductive tape is connected to the positive terminal of the power supply, and the negative conductive tape is connected to the negative terminal of the power supply. Maxwell stress is generated between the two conductive tapes, gradually pulling the two conductive tapes closer until they are almost touching. Pressurization and pumping of the liquid dielectric in the first bag cavity cause the area without conductive tape to arch, applying tension to the two side hardened layers and causing a large-angle bend θ at the joint. The elastic hinge layer is in a stretched state. At this time, the surface length of the first polyethylene film is the length of the polyethylene film at the horizontal position plus the length of the polyethylene film at the arched position, i.e., Z + l, and Z + l = L + ΔL0. After power is cut off, the Maxwell stress between the two layers of conductive adhesive tape disappears, the optocoupler and resistor of the power supply module discharge, the liquid flows back, the first hydraulic amplification self-healing actuator returns to its initial state, and the hardened layers on both sides return to their initial positions under the elastic restoring force of the elastic hinge layer. By cyclically switching the power on and off at a certain frequency, the reciprocating oscillation of the hardened layers on both sides can be achieved.

[0011] Furthermore, the second hydraulic amplification self-healing actuator is made of a second polyethylene film and a second double-sided conductive adhesive tape, and is in the shape of a long bag. Its interior forms a second bag cavity. The second hydraulic amplification self-healing actuator is a folded hydraulic amplification self-healing actuator. The second bag cavity of the second hydraulic amplification self-healing actuator is uniformly filled with liquid dielectric. After being folded, it is symmetrically pasted on the front and rear sides of the pitch unit, and has good flexibility.

[0012] Furthermore, the pitch unit includes a connecting rod, a base, a bearing mounting base, and a bearing. Both ends of the connecting rod are connected to the bearings, the bearings are located inside the bearing mounting base, and the base is located on the connecting rod and is rotatable.

[0013] Furthermore, the two side hardened layers and the first intermediate hardened layer have a flat structure. The overall shape of the two side hardened layers is wing-shaped to improve swimming speed and reduce forward drag. The two side hardened layers and the first intermediate hardened layer are made of 1mm thick black acrylic sheet. The overall shape of the two side hardened layers and the first intermediate hardened layer is cut by a CNC laser engraving machine.

[0014] Furthermore, the pre-stretch length of the elastic hinge layer is 1 mm to provide elastic restoring force when the joint is bent. The elastic hinge layer is made of polydimethylsiloxane (PDMS) film. Preferably, the tensile strength is 4.2 MPa, the elastic modulus is 0.6 MPa, and the pre-stretch length is 1 mm.

[0015] Furthermore, the flexible wave fin is blade-shaped and symmetrically bonded to the hardened layers on both sides. The joint fits together and can swing up and down with the reciprocating motion of the hardened layers on both sides, presenting a periodic wave motion, which propels the actuator forward. The flexible wave fin is made of a silicone film with a thickness of 0.2mm.

[0016] Furthermore, both the first hydraulic amplification self-healing actuator and the second hydraulic amplification self-healing actuator are made of transparent polyethylene film, double-sided conductive tape, and dimethyl silicone oil with a viscosity of 0.65 cst, using a CNC heat sealing machine. The dimethyl silicone oil is the liquid dielectric of the first hydraulic amplification self-healing actuator and the second hydraulic amplification self-healing actuator.

[0017] Furthermore, the first polyethylene film consists of two 30μm thick polyethylene films stacked together. Double-sided conductive tape is applied to both sides of the stacked polyethylene films. One side of the stacked polyethylene films is then covered with an 80μm thick polyethylene film, and the other side with a 30μm thick polyethylene film. This ensures that the hydraulically amplified self-healing actuator, after being energized, can undergo significant deformation without being punctured or damaged. Polyethylene film has advantages such as wear resistance, chemical resistance, and low cost. It also possesses rubber-like elasticity and plasticity, allowing it to melt and bond under high temperatures, exhibiting certain self-healing properties. This satisfies the requirements of heat sealing and handheld soldering iron sealing operations in this invention.

[0018] Furthermore, the bearing is a deep groove ball bearing, and the base, connecting rod, and bearing mounting seat are manufactured using 3D printing.

[0019] The working principle of this invention is as follows: Step 1: The first hydraulically amplified self-healing actuator and the elastic hinge layer of the drive module are used to apply selective constraints and elastic restoring forces to the hardened layers on both sides of the drive module, thereby driving the flexible wave fin and realizing the forward movement of the actuator.

[0020] Step 2: Power on and off the two sets of second hydraulic amplification self-healing actuators of the pitch control module respectively, thereby changing the tilt degree of the pitch unit and realizing the pitch movement of the actuator.

[0021] Step 3: Apply a DC high voltage of kilovolts to the first double-sided conductive tape of the first hydraulic amplification self-healing driver of the drive module. Maxwell stress gradually tightens the first double-sided conductive tape filled with fluid between the two layers, pressurizes and pumps the fluid, and the hydrostatic pressure plus selective constraint causes the joint to bend downward.

[0022] Step 4: De-energize the first double-sided conductive tape of the first hydraulic amplification self-healing actuator in Step 3. The two layers of the first double-sided conductive tape lose the effect of Maxwell stress and are discharged through the optocoupler and resistor of the power supply module. The liquid flows back and, under the elastic restoring force of the elastic hinge layer, the joint recovers to the upward side.

[0023] Step 5: Apply a DC high voltage of kilovolts to the double-sided conductive tape of the hydraulic amplification self-healing actuator on the front side of the pitch unit of the pitch control module. Maxwell stress gradually tightens the double-sided conductive tape, pressurizes and pumps the fluid, and the folded hydraulic amplification self-healing actuator arches up at the part without double-sided conductive tape, changing the tilt degree of the pitch mechanism and realizing the upward movement of the actuator.

[0024] Step 6: De-energize the second hydraulic amplification self-healing actuator on the front side of the pitch unit of the pitch control module, restore the arched second hydraulic amplification self-healing actuator, apply a DC high voltage of kilovolts to the second double-sided conductive tape of the rear second hydraulic amplification self-healing actuator, and the folded rear second hydraulic amplification self-healing actuator arches up, causing the pitch unit to tilt in the other direction, thereby realizing the actuator's sinking movement.

[0025] Step 7: By repeating steps 3 and 4, periodic oscillations are generated, which in turn produce a stable propulsive force, enabling the actuator to move forward. Steps 5 and 6 are used to achieve the actuator's upward and downward movements.

[0026] The manufacturing process of the first and second hydraulic amplification self-healing actuators includes material preparation, cutting of double-sided conductive tape, cutting and heat sealing of film, assembly of actuators, and sealing test of actuators.

[0027] Compared with the prior art, the present invention has the following advantages: This actuator, modeled after a manta ray, boasts excellent driving performance. This invention enables multi-stage parallel operation, thereby enhancing the driving capability of the flexible actuator. Effective multi-directional movement can be achieved through simple module fabrication and control. Employing specific flexible materials and structures, it possesses elasticity and chemical resistance. Specifically, upon collision with external objects, it can generate a larger deformation relative to the object, effectively solving the problem of component damage caused by external impacts; it can also withstand and resist corrosion, erosion, and damage to its surface and interior by chemical substances to a certain extent. Furthermore, the pre-stretched elastic hinge layer provides elastic restoring force, maximizing energy utilization. Attached Figure Description

[0028] Figure 1 This is a structural diagram of the driver module.

[0029] Figure 2a This is a top view of the driver module.

[0030] Figure 2b This is a front view of the driver module.

[0031] Figure 2c This is a top view of the drive module.

[0032] Figure 3 This is a schematic diagram of a hydraulically amplified self-healing actuator for a pitch control module.

[0033] Figure 4 This is a structural diagram of the pitch control module.

[0034] Figure 5 This is a flowchart illustrating the manufacturing process of a hydraulic amplification self-healing actuator.

[0035] Figure 6 This is a structural diagram of the actuator.

[0036] Figure 7a Schematic diagram of the first hydraulic amplification self-healing actuator Figure 1 .

[0037] Figure 7b The second schematic diagram shows the principle of the first hydraulic amplification self-healing actuator.

[0038] Reference numerals: 2-1: Flexible undulating fin; 2-2: Hardened layers on both sides; 2-3: Elastic hinge layer; 2-4: First intermediate hardened layer; 2-5: First hydraulic amplification self-healing actuator; 4-1: Second polyethylene film; 4-2: Second double-sided conductive tape; 5-1: Second intermediate hardened layer; 5-2: Pitch unit; 5-3: Second hydraulic amplification self-healing actuator; 7-7: Bearing; 7-8: Base; 7-9: Connecting rod; 7-10: Bearing fixing seat; 8-3: First polyethylene film; 8-4: First cavity; 8-5: Positive conductive tape; 8-6: Negative conductive tape. Detailed Implementation

[0039] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. Component models, material names, connection structures, control methods, algorithms, and other features not explicitly described in this technical solution are considered common technical features disclosed in the prior art.

[0040] Example 1 This embodiment provides an underwater biomimetic flexible actuator based on electrostatic hydraulic drive, including a drive module, a pitch control module, and a power supply module; the pitch control module is located on the drive module, and the power supply module is connected to both the drive module and the pitch control module; like Figure 1 , Figure 2a , 2b As shown in Figure 2c, the drive module is used to realize the forward movement of the actuator. The drive module includes: a flexible undulating fin 2-1, two hardened layers 2-2 on both sides, an elastic hinge layer 2-3, a first intermediate hardened layer 2-4, and a first hydraulically amplified self-healing actuator 2-5. The flexible undulating fin 2-1 is connected to the two hardened layers 2-2 on both sides. The first hydraulically amplified self-healing actuator 2-5 is adhered to the first intermediate hardened layer 2-4. The elastic hinge layer 2-3 is symmetrically adhered to the lower side of the first intermediate hardened layer 2-4. The elastic hinge layer 2-3 is in a pre-stretched state. The first intermediate hardened layer 2-4 and the two hardened layers 2-2 are hinged through the elastic hinge layer 2-3. The elastic hinge layer 2-3 provides elastic restoring force for the bent joint. After bending at the joint between the two hardened layers 2-2 and the first intermediate hardened layer 2-4, due to hydrostatic pressure, the joint may not recover in time or fully. The elastic hinge layer 2-3 provides a certain elastic restoring force, which can reduce the occurrence of untimely or incomplete recovery to a certain extent.

[0041] like Figure 4As shown, the pitch control module is used to realize the upward and downward movement of the actuator. The pitch control module includes: a second intermediate hardened layer 5-1, a pitch unit 5-2, and a second hydraulic amplification self-healing actuator 5-3. The pitch unit 5-2 and the second hydraulic amplification self-healing actuator 5-3 are both installed on the second intermediate hardened layer 5-1. There are two sets of the second hydraulic amplification self-healing actuator 5-3, which are respectively located at the front end and the rear end of the second intermediate hardened layer 5-1. When the second hydraulic amplification self-healing actuator 5-3 at the front end or the rear end is energized, the end of the second hydraulic amplification self-healing actuator 5-3 near the pitch unit 5-2 will arch up, changing the tilt degree of the base 7-8 of the pitch unit 5-2, thereby causing the actuator to float or sink.

[0042] The power supply module includes an STM32 microcontroller, a small high-voltage driver board, and an optocoupler. The STM32 microcontroller controls the voltage and frequency of the small high-voltage driver board in real time, and the optocoupler and resistor discharge residual charge, thus controlling the voltage output of the driver module and the pitch control module.

[0043] In a specific embodiment, the first hydraulic amplification self-healing actuator 2-5 is bag-shaped, with its interior forming a first cavity 8-4. The first hydraulic amplification self-healing actuator 2-5 facilitates adhesion to the hardened layer and provides selective constraint. The first hydraulic amplification self-healing actuator 2-5 is made of a first polyethylene film 8-3 and a first double-sided conductive adhesive tape. The first double-sided conductive adhesive tape includes a positive conductive tape 8-5 and a negative conductive tape 8-6, possessing a certain degree of elasticity and flexibility. The first cavity 8-4 of the first hydraulic amplification self-healing actuator 2-5 is uniformly filled with a liquid dielectric. The first hydraulic amplification self-healing actuator 2-5 is symmetrically attached to the opposite sides of the elastic hinge layer 2-3 using cloth-based double-sided adhesive tape, used to drive the hardened layers 2-2 on both sides to swing, thereby driving the flexible oscillating fin 2-1.

[0044] The first hydraulic amplification self-healing actuator 2-5 is normally a flat structure. When the two skirts of the first double-sided conductive adhesive tape are energized, the tape gradually adheres due to Maxwell stress, pumping liquid and causing the area without the tape to arch, leading to bending of the joint. After power is cut off, the liquid flows back, evenly filling the first cavity 8-4, and the hardened layers 2-2 on both sides return to normal. Figure 1 The initial position. By cyclically switching the power on and off, the hardened layers 2-2 on both sides and the flexible undulating fin 2-1 can be made to swing back and forth, thereby realizing the forward movement of the actuator.

[0045] like Figure 7aThe first hydraulic amplified self-healing actuator 2-5 is in its initial state, with no current flowing through the first double-sided conductive adhesive tape. The first cavity 8-4 is filled with a uniform liquid dielectric. The joint between the first intermediate hardened layer 2-4 and the two side hardened layers 2-2 is in a horizontal state. The elastic hinge layer 2-3 is in a pre-stretched state. At this time, the arc length of the surface of the first polyethylene film 8-3 is L+ΔL0. Figure 7b As shown, when a DC voltage on the order of kilovolts is applied to the first double-sided conductive tape, with the positive conductive tape 8-5 connected to the positive terminal of the power supply and the negative conductive tape 8-6 connected to the negative terminal, Maxwell stress is generated between the two layers of conductive tape, gradually pulling them closer until they are almost touching. Pressurization and pumping of the liquid dielectric in the first cavity 8-4 cause the area without conductive tape to arch, applying tension to the hardened layers 2-2 on both sides, resulting in a large-angle bend θ at the joint. The elastic hinge layer 2-3 is in a stretched state. At this time, the surface length of the first polyethylene film 8-3 is the sum of the length of the polyethylene film at the horizontal position and the length of the polyethylene film at the arched position, i.e., Z+l, where Z+l=L+ΔL0. After power is cut off, the Maxwell stress between the two layers of conductive tape disappears, the optocoupler and resistor of the power supply module discharge, the liquid flows back, and the first hydraulic amplification self-healing actuator 2-5 returns to its original position. Figure 7a In its initial state, the hardened layers 2-2 on both sides return to their initial position under the elastic restoring force of the elastic hinge layer 2-3. By cyclically switching the power on and off at a certain frequency, the hardened layers 2-2 on both sides can be made to swing back and forth.

[0046] like Figure 3 As shown, in a specific embodiment, the second hydraulic amplification self-healing actuator 5-3 is made of a second polyethylene film 4-1 and a second double-sided conductive adhesive tape 4-2, and is in the shape of a long bag. Its interior forms a second bag cavity. The second hydraulic amplification self-healing actuator 5-3 is a folded hydraulic amplification self-healing actuator. The second bag cavity of the second hydraulic amplification self-healing actuator 5-3 is uniformly filled with liquid dielectric. After being folded, it is symmetrically pasted on the front and rear sides of the pitch unit 5-2, and has good flexibility.

[0047] like Figure 6 As shown, in a specific embodiment, the pitch unit 5-2 includes a connecting rod 7-9, a base 7-8, a bearing fixing seat 7-10, and a bearing 7-7. Both ends of the connecting rod 7-9 are connected to the bearing 7-7, the bearing 7-7 is located inside the bearing fixing seat 7-10, and the base 7-8 is located on the connecting rod 7-9 and can rotate.

[0048] In a specific embodiment, the two side hardened layers 2-2 and the first intermediate hardened layer 2-4 have a flat structure. The overall shape of the two side hardened layers 2-2 is wing-shaped to improve swimming speed and reduce forward resistance. The two side hardened layers 2-2 and the first intermediate hardened layer 2-4 are made of 1mm thick black acrylic sheet. The overall shape of the two side hardened layers 2-2 and the first intermediate hardened layer 2-4 is cut by a CNC laser engraving machine.

[0049] In a specific embodiment, the pre-stretch length of the elastic hinge layer 2-3 is 1 mm, which is used to provide elastic restoring force when the joint is bent. The elastic hinge layer 2-3 is made of polydimethylsiloxane (PDMS) film. Preferably, the tensile strength is 4.2 MPa, the elastic modulus is 0.6 MPa, and the pre-stretch length is 1 mm.

[0050] In a specific embodiment, the flexible wave fin 2-1 is blade-shaped and symmetrically bonded to the two hardened layers 2-2 on both sides. The connection is well-fitted and can swing up and down with the reciprocating motion of the two hardened layers 2-2, presenting a periodic wave motion, which propels the actuator forward. The flexible wave fin 2-1 is made of a silicone film with a thickness of 0.2mm.

[0051] In a specific embodiment, both the first hydraulic amplification self-healing actuator 2-5 and the second hydraulic amplification self-healing actuator 5-3 are made of transparent polyethylene film, double-sided conductive tape and dimethyl silicone oil with a viscosity of 0.65 cst, and are prepared by a CNC heat sealing machine. The dimethyl silicone oil is the liquid dielectric of the first hydraulic amplification self-healing actuator 2-5 and the second hydraulic amplification self-healing actuator 5-3.

[0052] In a specific embodiment, the first polyethylene film 8-3 is composed of two layers of polyethylene film with a thickness of 30μm stacked together. Double-sided conductive tape is applied to both sides of the stacked polyethylene film. Then, an 80μm thick polyethylene film is applied to one side of the stacked polyethylene film, and a 30μm thick polyethylene film is applied to the other side. This ensures that the hydraulic amplification self-healing actuator, after being energized, can undergo significant deformation without being punctured or damaged. Polyethylene film has advantages such as wear resistance, chemical resistance, and low cost. It also possesses rubber-like elasticity and plasticity, and under high-temperature conditions, it can melt and bond, exhibiting certain self-healing properties, thus satisfying the requirements of heat sealing and handheld soldering iron sealing operations in this invention.

[0053] In a specific implementation, bearing 7-7 is a deep groove ball bearing 684, and base 7-8, connecting rod 7-9 and bearing fixing seat 7-10 are manufactured by 3D printing.

[0054] In a specific implementation, the actuator has a length of 280mm-300mm and a width of 110mm.

[0055] The working principle of this invention is as follows: Step 1: The first hydraulically amplified self-healing actuator 2-5 and the elastic hinge layer 2-3 of the drive module are used to apply selective constraint and elastic recovery force to the hardened layers 2-2 on both sides of the drive module, thereby driving the flexible wave fin 2-1 and realizing the forward movement of the actuator.

[0056] Step 2: Power on and off the two sets of second hydraulic amplification self-healing actuators 5-3 of the pitch control module respectively, thereby changing the tilt degree of the pitch unit and realizing the pitch movement of the actuator.

[0057] Step 3: Apply a DC high voltage of kilovolts to the first double-sided conductive tape of the first hydraulic amplification self-healing actuator 2-5 of the drive module. Maxwell stress gradually tightens the first double-sided conductive tape filled with fluid between the two layers, pressurizes and pumps the fluid, and the hydrostatic pressure plus selective constraint causes the joint to bend downward.

[0058] Step 4: De-energize the first double-sided conductive tape of the first hydraulic amplification self-healing actuator 2-5 in Step 3. The two layers of the first double-sided conductive tape lose the effect of Maxwell stress and are discharged through the optocoupler and resistor of the power supply module. The liquid flows back and the joint recovers to the upper side under the elastic restoring force of the elastic hinge layer 2-3.

[0059] Step 5: Apply a DC high voltage of kilovolts to the double-sided conductive tape of the hydraulic amplification self-healing actuator on the front side of the pitch unit of the pitch control module. Maxwell stress gradually tightens the double-sided conductive tape, pressurizes and pumps the fluid, and the folded hydraulic amplification self-healing actuator arches up at the part without double-sided conductive tape, changing the tilt degree of the pitch mechanism and realizing the upward movement of the actuator.

[0060] Step 6: De-energize the second hydraulic amplification self-healing actuator 5-3 on the front side of the pitch unit 5-2 of the pitch control module, restore the arched second hydraulic amplification self-healing actuator 5-3, apply a DC high voltage of kilovolts to the second double-sided conductive tape of the rear second hydraulic amplification self-healing actuator 5-3, and the rear folded second hydraulic amplification self-healing actuator 5-3 arches up, causing the pitch unit 5-2 to tilt in the other direction, realizing the actuator's sinking movement.

[0061] Step 7: By repeating steps 3 and 4, periodic oscillations are generated, which in turn produce a stable propulsive force, enabling the actuator to move forward. Steps 5 and 6 are used to achieve the actuator's upward and downward movements.

[0062] The manufacturing process of the first hydraulic amplification self-healing actuator 2-5 and the second hydraulic amplification self-healing actuator 5-3 is as follows: Figure 5As shown, the process includes material preparation, cutting of double-sided conductive tape, cutting and heat sealing of film, assembly of driver, and testing of driver sealing.

[0063] Components not described in detail in this embodiment are all existing components that can be purchased through public channels.

[0064] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. An underwater biomimetic flexible actuator based on electrostatic hydraulic drive, characterized in that, It includes a drive module, a pitch control module, and a power supply module; the pitch control module is mounted on the drive module, and the power supply module is connected to both the drive module and the pitch control module. The drive module is used to realize the forward movement of the actuator. The drive module includes: a flexible oscillating fin (2-1), two hardened layers (2-2), an elastic hinge layer (2-3), a first intermediate hardened layer (2-4), and a first hydraulic amplification self-healing actuator (2-5). The flexible oscillating fin (2-1) is connected to the two hardened layers (2-2). The first hydraulic amplification self-healing actuator (2-5) is adhered to the first intermediate hardened layer (2-4). The elastic hinge layer (2-3) is symmetrically adhered to the lower side of the first intermediate hardened layer (2-4). The elastic hinge layer (2-3) is in a pre-stretched state. The first intermediate hardened layer (2-4) and the two hardened layers (2-2) are hinged through the elastic hinge layer (2-3). The first hydraulic amplification self-healing actuator (2-5) is symmetrically attached to the opposite side of the elastic hinge layer (2-3) with double-sided cloth adhesive to drive the two hardened layers (2-2) to swing, thereby driving the flexible oscillating fin (2-1). The pitch control module is used to realize the upward and downward movement of the actuator. The pitch control module includes: a second intermediate hardened layer (5-1), a pitch unit (5-2), and a second hydraulic amplification self-healing actuator (5-3). The pitch unit (5-2) and the second hydraulic amplification self-healing actuator (5-3) are both installed on the second intermediate hardened layer (5-1). There are two sets of the second hydraulic amplification self-healing actuator (5-3), which are respectively located at the front end and the rear end of the second intermediate hardened layer (5-1). When the second hydraulic amplification self-healing actuator (5-3) at the front end or the rear end is energized, the end of the second hydraulic amplification self-healing actuator (5-3) near the pitch unit (5-2) will arch up, changing the tilt degree of the base (7-8) of the pitch unit (5-2), thereby realizing the upward or downward movement of the actuator.

2. The underwater biomimetic flexible actuator based on electrostatic hydraulic drive according to claim 1, characterized in that, The first hydraulic amplification self-healing actuator (2-5) is bag-shaped, with its interior forming a first cavity (8-4). The first hydraulic amplification self-healing actuator (2-5) is easy to bond with the hardened layer and provides selective constraint. The first hydraulic amplification self-healing actuator (2-5) is made of a first polyethylene film (8-3) and a first double-sided conductive tape. The first double-sided conductive tape includes a positive conductive tape (8-5) and a negative conductive tape (8-6). The positive conductive tape (8-5) is adhered to one side of the first polyethylene film (8-3), and the negative conductive tape (8-6) is adhered to the other side of the first polyethylene film (8-3). The first cavity (8-4) of the first hydraulic amplification self-healing actuator (2-5) is uniformly filled with a liquid dielectric.

3. The underwater biomimetic flexible actuator based on electrostatic hydraulic drive according to claim 1, characterized in that, The second hydraulic amplification self-healing actuator (5-3) is made of a second polyethylene film (4-1) and a second double-sided conductive tape (4-2), and is in the shape of a long bag. Its interior forms a second bag cavity. The second hydraulic amplification self-healing actuator (5-3) is a folded hydraulic amplification self-healing actuator. The second bag cavity of the second hydraulic amplification self-healing actuator (5-3) is uniformly filled with liquid dielectric. After being folded, the second hydraulic amplification self-healing actuator (5-3) is symmetrically pasted on the front and rear sides of the pitch unit (5-2).

4. The underwater biomimetic flexible actuator based on electrostatic hydraulic drive according to claim 1, characterized in that, The pitch unit (5-2) includes a connecting rod (7-9), a base (7-8), a bearing mounting seat (7-10), and a bearing (7-7). Both ends of the connecting rod (7-9) are connected to the bearing (7-7). The bearing (7-7) is located inside the bearing mounting seat (7-10). The base (7-8) is located on the connecting rod (7-9) and is rotatable.

5. The underwater biomimetic flexible actuator based on electrostatic hydraulic drive according to claim 1, characterized in that, The two hardened layers (2-2) and the first intermediate hardened layer (2-4) are flat structures. The overall shape of the two hardened layers (2-2) is wing-shaped, which is used to improve the swimming speed and reduce forward resistance. The two hardened layers (2-2) and the first intermediate hardened layer (2-4) are made of black acrylic sheet with a thickness of 1mm.

6. The underwater biomimetic flexible actuator based on electrostatic hydraulic drive according to claim 1, characterized in that, The pre-stretch length of the elastic hinge layer (2-3) is 1 mm, which is used to provide elastic restoring force when the joint is bent. The elastic hinge layer (2-3) is made of polydimethylsiloxane PDMS film.

7. The underwater biomimetic flexible actuator based on electrostatic hydraulic drive according to claim 1, characterized in that, The flexible wave fin (2-1) is blade-shaped and symmetrically bonded to the two hardened layers (2-2) on both sides. The connection is well-fitted and can swing up and down with the reciprocating motion of the two hardened layers (2-2), presenting a periodic wave motion, which propels the actuator forward. The flexible wave fin (2-1) is made of a silicone film with a thickness of 0.2mm.

8. The underwater biomimetic flexible actuator based on electrostatic hydraulic drive according to claim 1, characterized in that, The first hydraulic amplification self-healing actuator (2-5) and the second hydraulic amplification self-healing actuator (5-3) are both made of transparent polyethylene film, double-sided conductive tape and dimethyl silicone oil with a viscosity of 0.65 cst, and are prepared by CNC heat sealing machine. The dimethyl silicone oil is the liquid dielectric of the first hydraulic amplification self-healing actuator (2-5) and the second hydraulic amplification self-healing actuator (5-3).

9. The underwater biomimetic flexible actuator based on electrostatic hydraulic drive according to claim 2, characterized in that, The first polyethylene film (8-3) is made of two layers of polyethylene film with a thickness of 30μm stacked together. After double-sided conductive tape is attached to both sides of the stacked polyethylene film, a layer of polyethylene film with a thickness of 80μm is attached to one side of the stacked polyethylene film and a layer of polyethylene film with a thickness of 30μm is attached to the other side, so as to ensure that the hydraulic amplification self-healing actuator can generate large deformation without being broken down or damaged after being powered on.

10. An underwater biomimetic flexible actuator based on electrostatic hydraulic drive according to claim 4, characterized in that, The bearing (7-7) is a deep groove ball bearing 684, and the base (7-8), connecting rod (7-9) and bearing fixing seat (7-10) are all made by 3D printing.

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