Flexible bionic sensor, bionic whisker array unit and underwater vehicle

Abstract

The invention relates to a flexible bionic sensor, a bionic whisker array unit and an underwater vehicle. The flexible bionic sensor comprises a flexible corrugated sleeve, a shell, at least four friction nanometer power generation units, a collision unit and a beard shaft. A sealing cavity is formed in the flexible corrugated sleeve, and one end of the sealing cavity is a deformable corrugated part; an opening is formed in one side of the shell, the shell is connected into the sealing cavity, and the opening faces the corrugated part; the friction nanometer power generation units are uniformly connected in the circumferential direction of the inner wall of the shell; the collision unit comprises an elastic body and a collision body. According to the underwater sensing unit, by simulating the structure of seal beards and integrating the triboelectric nano-generator in a contact separation mode, tiny flow field interference is converted into electric signals, so that various near-field information including flow velocity, attack angle and wake information of a three-dimensional flow field can be obtained at the same time, and meanwhile, the defects of an existing underwater sensing unit are overcome; the method has the advantages of short response time, high sensitivity, high signal-to-noise ratio, no environmental limitation and the like.

Description

Technical Field

[0001] The present invention relates to the field of perception and navigation technology, and in particular to a flexible bionic sensor, a bionic whisker array unit and an underwater vehicle. Background Art

[0002] In the fields of ocean research, maritime search and rescue, and environmental monitoring, the flow field perception capability of underwater robots or vehicles is crucial. Commonly used perception tools for these devices include optical sensors and acoustic sensors, but they each have their own shortcomings. For example, the performance of optical sensors may be affected by environmental factors such as water turbidity and lighting conditions; optical sensors have high requirements for alignment and calibration. Sound waves may encounter multiple paths when propagating underwater, which will affect the accuracy and reliability of acoustic sensors; there may be delays in acoustic sensor signal processing, etc. The above shortcomings will limit the sensor's ability to perceive flow fields, thereby limiting the accuracy and reliability of sensor perception. Summary of the invention

[0003] Based on this, it is necessary to provide a flexible bionic sensor, a bionic whisker array unit and an underwater vehicle to address the problem that the existing underwater sensing units have limited flow field sensing capabilities in complex underwater environments.

[0004] A flexible bionic sensor is used to sense the flow field changes in the environment and generate corresponding electrical signals; the flexible bionic sensor comprises:

[0005] The whisker axis is used to sense the flow field changes in the environment and generate corresponding vibrations;

[0006] A flexible bellows sleeve, the interior of which forms a sealed cavity, and one end of which is a deformable bellows portion;

[0007] a housing mounted in the sealed cavity;

[0008] At least four friction nano-power generation units are uniformly fixed circumferentially on the inner wall of the housing;

[0009] A collision unit comprises an elastomer and a collision body; one end of the elastomer is connected to the inner wall of the shell away from the corrugated portion, and the other end is connected to the collision body; one end of the whisker shaft passes through the corrugated portion and is connected to the collision body; in an initial state, the elastomer, the collision body and the whisker shaft are located on the same axis, and the distance between the axis and each friction nano power generation unit is equal; the collision body is located in the shell, and is used for colliding with the friction nano power generation unit after being affected by the whisker shaft to generate corresponding vibration, and the friction nano power generation unit generates a corresponding electrical signal after the collision.

[0010] As a preferred example, an opening is provided on one side of the shell facing the corrugated portion; the whisker axis passes through the opening and is connected to the collision body; the inner cavity of the shell is set to a cubic shape, and the four inner walls of the shell perpendicular to the opening are all connected to the friction nano power generation unit.

[0011] As a preferred example, the friction nano power generation unit includes an elastic sleeve, a conductive ink layer and a thin film layer; the conductive ink layer and the thin film layer are respectively connected to the two opposite inner walls of the elastic sleeve; the outer side of one end of the elastic sleeve connecting the conductive ink layer or the thin film layer is connected to the inner wall of the outer shell, and the outer side of the other end corresponds to the collision body.

[0012] As a preferred example, a blind hole is formed at one end of the collision body away from the elastic body, and one end of the whisker shaft extends into the blind hole and is fixed to the collision body.

[0013] As a preferred example, the elastic body is set as a spring or an elastic rod; the collision body is set as a sphere made of PLA material.

[0014] As a preferred example, the whisker shaft includes a transmission rod and an elliptical cylinder located outside the flexible corrugated sleeve; one end of the transmission rod is connected to the collision body, and the other end passes through the corrugated part and is coaxially connected to the elliptical cylinder.

[0015] As a preferred example, the length ratio of the major axis to the minor axis of the elliptical cylinder is 12.4:5.

[0016] As a preferred example, the flexible bionic sensor further comprises a base; one end of the flexible bellows sleeve away from the bellows portion is connected to the base; and one side of the housing away from the bellows portion is connected to the base.

[0017] A bionic whisker array unit comprises at least four flexible bionic sensors as described above; a plurality of the flexible bionic sensors are commonly connected to a fixing seat.

[0018] An underwater vehicle comprises a vehicle body and at least one bionic whisker array unit as described above; the bionic whisker array unit is installed at the head position of the vehicle body.

[0019] The beneficial effects of the present invention are:

[0020] 1. The present invention imitates the structure of seal whiskers and integrates a friction electric nanogenerator in contact-separation mode to convert tiny flow field disturbances into electrical signals, thereby being able to simultaneously obtain a variety of near-field information, including flow velocity, angle of attack and wake information of the three-dimensional flow field. At the same time, the present invention overcomes the shortcomings of existing underwater sensing units, is not affected by water quality, propagation path, etc., and has the advantages of short response time, high sensitivity, high signal-to-noise ratio, and no environmental restrictions.

[0021] 2. The present invention can identify the continuous change of the angle of attack and accurately detect the upstream wake vortex characteristics. The underwater vehicle using the present invention can provide effective near-flow field information based on the perception of bionic whiskers, help the underwater vehicle complete local navigation tasks, and bring revolutionary improvements to applications such as marine research, search and rescue, and environmental monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The overall structure diagram of the flexible bionic sensor in the embodiment;

[0023] Figure 2 Schematic diagram of the internal structure of the flexible bionic sensor in the embodiment;

[0024] Figure 3 A schematic diagram of the structure of a friction nano power generation unit in an embodiment;

[0025] Figure 4 It is a schematic diagram of the structure of installing a bionic whisker array unit on an underwater vehicle in an embodiment;

[0026] Figure 5 is a graph showing the relationship between the voltage output main frequency signal of the friction nano power generation unit and the flow rate in the embodiment;

[0027] Figure 6 is a graph showing the relationship between the voltage output information of the friction nano power generation unit and the angle of attack in the embodiment;

[0028] Figure 7 It is a simulation diagram of the whisker shaft at different attack angles in the embodiment;

[0029] Figure 8 Graph showing the relationship between the flexible bionic sensor and the front shedding eddy current in the embodiment.

[0030] In the figure: a flexible corrugated sleeve 1, a corrugated portion 11, an outer shell 2, a friction nano power generation unit 3, an elastic sleeve 31, a conductive ink layer 32, a film layer 33, an elastomer 4, a collision body 5, a transmission rod 6, an elliptical cylinder 7, a base 8, and a vehicle body 9. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions 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. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] It should be noted that when a component is referred to as being "mounted on" another component, it may be directly on the other component or there may be a central component. When a component is considered to be "set on" another component, it may be directly set on the other component or there may be a central component at the same time. When a component is considered to be "fixed to" another component, it may be directly fixed on the other component or there may be a central component at the same time.

[0033] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "or / and" used herein includes any and all combinations of one or more of the related listed items.

[0035] Please refer to Figure 1 and Figure 2 In this embodiment, a flexible bionic sensor is provided, which includes a flexible corrugated sleeve 1, an outer shell 2, four friction nano-power generation units 3, a collision unit and a whisker shaft. The flexible corrugated sleeve 1 can be made of silicone material as a whole, one end of which is set to a deformable and shaking corrugated part 11, and the other end is fixed to the base 8 by epoxy resin adhesive, so that a sealed cavity is formed inside the flexible corrugated sleeve 1 to ensure the water tightness of the flexible bionic sensor. The outer shell 2 is made of hard material, and one end of it is provided with an opening, and is arranged in the direction of the corrugated part 11. The other end of the outer shell 2 is fixed to the base 8. The outer shell 2 is entirely located in the sealed cavity, and the flexible corrugated sleeve 1 is wrapped on the outer wall of the outer shell 2. The inner cavity of the outer shell 2 is set to a square shape, that is, except for one side with an opening, the inner cavity of the outer shell 2 includes five faces. The four friction nano-power generation units 3 are fixed on four faces perpendicular to the opening side. A friction nano-power generation unit 3 is fixed on each face. The friction nano-power generation unit 3 can use a friction nano-generator in contact-separation mode. As Figure 3As shown, the friction nano power generation unit 3 includes an elastic sleeve 31, a conductive ink layer 32 and a FEP film layer 33. The conductive ink layer 32 and the film layer 33 are respectively connected to the two opposite inner walls of the elastic sleeve 31, and the whole is encapsulated to form a unit. The elastic sleeve 31 can be made of silicone. The outer side of one end of the elastic sleeve 31 connected to the conductive ink layer 32 or the film layer 33 is connected to the inner wall of the shell 2, and the outer side of the other end corresponds to the collision body 5. When the two materials set in the friction nano power generation unit 3 are vertically contacted and separated, due to contact electrification and electrostatic induction effects, current will be generated in the external circuit. In some other embodiments, the conductive ink layer 32 and the FEP film layer 33 can be replaced by some other friction materials to improve the sensitivity and durability of the sensing unit, so that a higher charge density is generated during the contact and separation process, thereby enhancing the strength and stability of the signal.

[0036] The collision unit includes an elastomer 4 and a collision body 5. In this embodiment, the elastomer 4 is a spring, and a structure or material that is elastic and can quickly return to its original position, such as a plastic elastic rod or a metal elastic rod, can also be used. The collision body 5 can be a sphere made of PLA material. The spherical collision body 5 is arranged on the central axis of the space surrounded by the four friction nano-power generation units 3, so that the distance between the collision body 5 and the four friction nano-power generation units 3 is equal in the initial state (that is, when the whisker shaft is not subjected to force). At the same time, two blind holes are symmetrically opened on the collision body 5. One of the blind holes is fixed to one end of the elastomer 4. The other end of the elastomer 4 is fixedly connected to the middle position of the inner wall of the outer shell 2 away from the corrugated portion 11 (that is, the side of the outer shell 2 away from the opening). The other blind hole is fixed to the whisker shaft.

[0037] The whisker shaft includes a transmission rod 6 made of carbon fiber and an elliptical cylinder 7 located outside the flexible corrugated sleeve 1. One end of the transmission rod 6 extends into the blind hole on the collision body 5 and is fixed thereto, and the other end passes through the corrugated portion 11 and is coaxially connected to the elliptical cylinder 7. The elliptical cylinder 7 can sense the vibration external force of the external flow field, and transmit the external force to the collision body 5 through the transmission rod 6, thereby driving the collision body 5 to impact the friction nano power generation unit 3, causing the friction nano power generation unit 3 to deform in the corresponding direction, thereby generating an electrical signal. Furthermore, the shape ratio of the elliptical cylinder 7 can be further designed, and the ratio of its major axis to minor axis length is 12.4:5. This ratio can effectively suppress fluid-induced vibrations and help optimize the accuracy of flow field perception. In addition, the shape of the elliptical cylinder 7 in the whisker shaft can also be replaced by other shapes, such as a cylinder, a prism or a custom shape, to optimize the perception of specific flow field characteristics. The choice of alternative shapes will be based on their dynamic response and perception efficiency under specific flow conditions. In the specific process of generating current, the conductive ink layer 32 contacts the FEP film layer 33, resulting in an overlap of the electron clouds between the two layers. Since the electronegativity of the film layer 33 is higher than that of the conductive ink layer 32, electrons migrate from the conductive ink layer 32 to the deeper potential well of the film layer 33, thereby generating a voltage signal. When the external stimulus disappears, the elastic deformation of the elastic sleeve 31 causes the film membrane to separate from the electrode of the conductive ink layer 32. This separation generates a dipole moment and a potential difference between the two contact surfaces because the positive and negative friction charges are no longer arranged on the same plane. Subsequently, the free electrons are transferred through the external circuit to balance the local electric field. This causes the electrode of the conductive ink layer 32 to be positively charged until the distance between the conductive ink layer 32 and the film layer 33 is equal. At this point, no more friction electrification or electrostatic induction is generated between the two layers. Finally, the charge distribution returns to the initial state, completing the cycle. During this process, the generated electrical signals are analyzed through some deep learning models and mapped to aspects such as the speed, angle and obstacle estimation of the underwater robot, so that the near-field flow field of the underwater vehicle can be effectively perceived, providing accurate information for three-dimensional path planning and obstacle detection.

[0038] In another embodiment, a bionic whisker array unit is also proposed based on the above-mentioned flexible bionic sensor. The bionic whisker array unit includes at least four flexible bionic sensors as described above. Multiple flexible bionic sensors can be fixed on the same fixing seat and symmetrically distributed along the symmetry plane of the fixing seat. An underwater vehicle and an underwater robot are also proposed. The underwater vehicle includes a vehicle body 9 and at least one bionic whisker array unit as described above. The bionic whisker array unit is installed at the head position of the vehicle body 9, such as Figure 4As shown, the length direction of the elliptical cylinder 7 is perpendicular to the forward direction of the vehicle body 9, simulating the whisker arrangement of a seal. The underwater robot includes a robot body and at least one bionic whisker array unit as described above. The bionic whisker array unit is also installed at the head position of the robot body, and is used to sense the approach flow field information of the underwater vehicle or underwater robot. In particular, the flexible bionic sensor can identify the continuous change of the angle of attack, and the detection accuracy of the upstream wake vortex characteristics exceeds 80%. The flexible bionic sensor is fixed on the autonomous underwater vehicle, and the path estimation and upstream wake perception are realized through the deep learning processing of multi-channel signals, and the root mean square error (RMSE) of the verification data is about 0.02, which can help the underwater vehicle complete the local navigation task, and bring revolutionary improvements to applications such as marine research, search and rescue, and environmental monitoring.

[0039] The design of the flexible bionic sensor of the present invention is inspired by the whiskers of the spotted seal and can sense the speed and direction of the water flow. One of the key points of the flexible bionic sensor is the elliptical whisker axis, and its dynamic characteristics can respond to the flow velocity and the angle change between the whisker axis and the flow direction. In a test pool with a size of 6000mm×3000mm×1500mm, the flexible bionic sensor provided in the above embodiment is installed on a towing platform. The towing platform can move independently along the x-axis and y-axis, with a speed range from 0mm / s to 500mm / s. The upper computer collects analog signals from the friction nano power generation unit 3, converts them into digital signals through amplifiers and AD7606, and stores them on the minimum system board. As Figure 5 As shown in the figure, when the flexible bionic sensor is installed on the towing platform, the output main frequency changes at different speeds. It can be seen from the figure that there is a linear relationship between the main frequency band of the flexible bionic sensor and the flow velocity.

[0040] In order to simulate different flow field conditions, an angle of attack (also called angle of attack) varying from 0° to 90° is defined, which is the angle between the long axis of the elliptical cylinder whisker shaft and the flow field direction. Using ANSYS Fluent fluid-structure coupling simulation software, the vortex characteristics of the flexible bionic sensor at different angles of attack are studied. The simulation results show that with the increase of the angle of attack, the size and frequency of the vortex will increase. In practical applications, the output signal amplitude and frequency of the flexible bionic sensor will change with the change of the angle of attack. Especially in the angle of attack range of 0° to 30°, the whisker shaft of the elliptical cylinder can effectively suppress self-excited vibration, thereby reducing the amplitude and frequency of the output signal. When the angle of attack is greater than 30°, the whisker shaft will produce obvious amplitude vibration, and the amplitude increases with the increase of the angle of attack. The simulation results are shown in the figure. Figure 6 shown.

[0041] Through fast Fourier transform (FFT) analysis, we can extract the dominant frequency signal from the original signal obtained from the friction nano power generation unit 3. These signals are mainly composed of the fundamental frequency caused by flow resistance and the main frequency caused by vortex-induced vibration (VIV). During the operation of the towing platform, the flexible bionic sensor can detect the periodic forces caused by the asymmetric vortex street. These external forces will periodically act on the collision body 5 in the flexible bionic sensor, and then hit the friction nano power generation unit 3. In addition, the effect of speed on the output of the flexible bionic sensor at an angle of attack of 90° was studied using ANSYS Fluent fluid-solid coupling simulation software. The results show that the frequency of the Karman vortex street behind the flexible bionic sensor increases significantly with the increase of speed, such as Figure 7 As shown in the simulation results, α is the angle of attack (angle of attack). On a rotating experimental platform, the flexible bionic sensor can simulate different water flow velocities, and the dominant frequency of the output signal increases with the increase of flow velocity, which proves that the flexible bionic sensor can effectively respond to changes in flow field velocity. Finally, through the analysis of vortex street parameters, the flexible bionic sensor can identify the vortex-induced vibration (VIV) caused by the Karman vortex street generated by the cylindrical blunt body. This shows that the flexible bionic sensor can suppress flow-induced vibration (WIV) at an angle of attack of 0° and has the ability to measure VIV.

[0042] The design of flexible bionic sensors is inspired by the perception ability of marine organisms, especially the ability of harbor seals to sense the speed and direction of water flow through their whiskers. By simulating this biological perception mechanism, flexible bionic sensors are able to measure and respond to flow changes in underwater environments. To study the response of flexible bionic sensors to vortex shedding frequency, we conducted experiments in a circulating water tank equipped with a particle image velocimeter (PIV). In the experiment, the flexible bionic sensor was placed on a test bench together with a cylindrical blunt body to simulate an obstacle in the water flow. The design of the test bench ensures the stability of the water flow while allowing us to adjust the flow rate by changing the motor speed. In the experiment, we observed that as the size of the cylinder increased, the subsequent shedding vortex also increased accordingly and the frequency decreased. This phenomenon is consistent with the theoretical prediction of vortex shedding frequency. We further studied the response characteristics of the flexible bionic sensor to vortices of different distances and sizes. The experimental results show that the flexible bionic sensor is able to detect the periodic oscillations caused by WIV through its friction nano-power generation unit 3 and generate corresponding voltage signals, such as Figure 8 shown.

[0043] In addition, we studied the vibration response of the flexible bionic sensor at different flow rates. The results show that the size of the upstream cylinder and the distance from the flexible bionic sensor have a significant effect on its vibration response. Larger upstream objects can cause vibrations in the flexible bionic sensor at a longer distance, and the maximum amplitude corresponds to a higher equivalent flow rate. Finally, we combined the flexible bionic sensor with an autonomous underwater vehicle (AUV) to test the flexible bionic sensor's ability to perceive obstacles ahead and to assess the AUV's own motion posture. Through a deep learning model, we were able to extract the AUV's state information, such as speed and angle, from the flexible bionic sensor's signal and accurately predict its trajectory. These experimental results demonstrate the potential application value of flexible bionic sensors in underwater vehicle navigation.

[0044] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0045] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A flexible bionic sensor, It is characterized in that It is used to sense the flow field changes in the environment and generate corresponding electrical signals; The flexible bionic sensor comprises: The whisker axis is used to sense the flow field changes in the environment and generate corresponding vibrations; A flexible bellows sleeve (1) having a sealed cavity formed therein and a deformable bellows portion (11) at one end thereof; A housing (2) mounted in the sealed cavity; At least four friction nano-power generation units (3) are evenly fixed circumferentially on the inner wall of the housing (2); A collision unit comprises an elastic body (4) and a collision body (5); one end of the elastic body (4) is connected to the inner wall of the outer shell (2) away from the corrugated portion (11), and the other end is connected to the collision body (5); one end of the whisker axis passes through the corrugated portion (11) and is connected to the collision body (5); in an initial state, the elastic body (4), the collision body (5) and the whisker axis are located on the same axis, and the distance between the axis and each friction nano power generation unit (3) is equal; the collision body (5) is located in the outer shell (2), and is used for colliding with the friction nano power generation unit (3) after being affected by the whisker axis to generate corresponding vibration, and the friction nano power generation unit (3) generates a corresponding electrical signal after the collision.

2. The flexible bionic sensor according to claim 1, It is characterized in that The outer shell (2) is provided with an opening on one side facing the corrugated portion (11); the whisker shaft passes through the opening and is connected to the collision body (5); the inner cavity of the outer shell (2) is arranged in a square shape, and the four inner walls of the outer shell (2) perpendicular to the opening are all connected to the friction nano power generation unit (3).

3. The flexible bionic sensor according to claim 1, It is characterized in that The friction nano power generation unit (3) comprises an elastic sleeve (31), a conductive ink layer (32) and a thin film layer (33); the conductive ink layer (32) and the thin film layer (33) are respectively connected to two opposite inner side walls of the elastic sleeve (31); the outer side of one end of the elastic sleeve (31) connected to the conductive ink layer (32) or the thin film layer (33) is connected to the inner wall of the outer shell (2), and the outer side of the other end corresponds to the collision body (5).

4. The flexible bionic sensor according to claim 1, It is characterized in that A blind hole is provided at one end of the collision body (5) away from the elastic body (4), and one end of the whisker shaft extends into the blind hole and is fixed to the collision body (5).

5. The flexible bionic sensor according to claim 1, It is characterized in that The elastic body (4) is configured as a spring or an elastic rod; and the collision body (5) is configured as a sphere made of PLA material.

6. The flexible bionic sensor according to claim 1, It is characterized in that The whisker shaft comprises a transmission rod (6) and an elliptical cylinder (7) located outside the flexible corrugated sleeve (1); one end of the transmission rod (6) is connected to the collision body (5), and the other end passes through the corrugated part (11) and is coaxially connected to the elliptical cylinder (7).

7. The flexible bionic sensor according to claim 6, It is characterized in that The length ratio of the major axis to the minor axis of the elliptical cylinder (7) is 12.4:

5.

8. The flexible bionic sensor according to claim 1, It is characterized in that The flexible bionic sensor also comprises a base (8); one end of the flexible corrugated sleeve (1) away from the corrugated portion (11) is connected to the base (8); and one side of the housing (2) away from the corrugated portion (11) is connected to the base (8).

9. A bionic whisker array unit, It is characterized in that It comprises at least four flexible bionic sensors according to any one of claims 1 to 8; a plurality of the flexible bionic sensors are commonly connected to a fixing seat.

10. An underwater vehicle, It is characterized in that It comprises an aircraft body (9) and at least one bionic whisker array unit as claimed in claim 9; the bionic whisker array unit is installed at the head position of the aircraft body (9).

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