Fishing net damage detecting and positioning device based on flexible sensing

Abstract

The invention relates to the technical field of fishing net detection, and discloses a fishing net damage detection and positioning device based on flexible sensing, the fishing net damage detection and positioning device comprises a fishing net body and steel ropes arranged at the upper and lower ends of the fishing net body, and one side of the fishing net body is provided with a plurality of warp sensing belt assemblies and weft sensing fiber assemblies which are arranged at equal intervals; a mesh-level sensing node assembly is arranged at the intersection of the warp sensing belt assembly and the weft sensing fiber assembly, and a plurality of bionic flexible supporting assemblies are arranged between the warp sensing belt assembly and the weft sensing fiber assembly; according to the device, the bending radius of the sensing device is reduced to 10mm through the flexible substrate, high-frequency bending during fishing net dragging can be borne, and meanwhile, the signal attenuation rate is low; according to the device, the stress concentration at the node is greatly reduced through the elastic buffer groove, the friction of the carbon nanotube sensing layer is isolated through the elastic substrate, and the service life is greatly prolonged; according to the device, a differential positioning algorithm is combined with a dense flexible sensing unit array, so that accurate positioning of a damaged position is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of fishing net detection, and in particular to a fishing net damage detection and positioning device based on flexible sensing. Background Art

[0002] Fishing net breakage is a common problem in fisheries. Existing fishing net breakage detection devices typically employ a fiber Bragg grating (FBG) sensing network. This FBG sensing network employs single-mode optical fiber with a Bragg grating (Bragg) point set every ten meters. Stainless steel clamps secure the optical fiber to the steel rope at the edge of the net using a breakage clamp. When the net breaks, causing local tension changes, the FBG attached to the net surface deforms with the net, causing the grating wavelength to change. A fiber optic spectrometer in the vessel's cabin scans the reflected light spectrum returned by the optical fiber in real time, measuring the wavelength offset of each grating. The damaged area is determined based on the spatial position of the grating on the optical fiber and the temporal sequence of the wavelength offsets.

[0003] However, this device structure has limitations. Fishing nets bend at a high frequency during trawling operations, while the bending radius of optical fibers needs to be greater than 30 mm, which cannot adapt to the high-frequency bending of fishing nets. At the same time, the interlaced friction of the longitude and latitude lines of the fishing net will cause optical fiber wear, especially at the mesh nodes, which is prone to stress concentration and causes grating wavelength drift errors. In addition, optical fibers have a certain rigidity, while fishing nets are flexible woven structures, and the deformation characteristics of the two are not matched. When a small tear occurs in the fishing net, the optical fiber may not be able to capture the local strain change due to the lack of synchronous deformation, resulting in missed detection. To cover a large area of ​​fishing nets, the grating spacing is usually set to be greater than 10, but damage smaller than this spacing may be between two gratings, making it impossible to locate the specific position. Summary of the Invention

[0004] The purpose of the present invention is to provide a fishing net damage detection and positioning device based on flexible sensing to solve the problems raised in the background technology.

[0005] To achieve the above objectives, the present invention provides the following technical solutions: a flexible sensing-based fishing net damage detection and positioning device, comprising a fishing net body and steel ropes disposed at the upper and lower ends of the fishing net body; a plurality of equally spaced warp sensing belt assemblies disposed on one side of the fishing net body; a plurality of equally spaced weft sensing fiber assemblies disposed perpendicularly to the warp sensing belt assemblies; a mesh-level sensing node assembly disposed at the intersection of the warp sensing belt assembly and the weft sensing fiber assemblies; a plurality of bionic flexible support assemblies disposed between the warp sensing belt assembly and the weft sensing fiber assemblies; and an electrical signal transmission assembly disposed at the edge of the fishing net body. The fishing net body comprises a warp rope and a longitudinal rope, and both ends of the warp rope are connected to steel ropes; The float keeps the fishing net body on the water surface or at a specific depth, maintaining the shape of the net body and facilitating fishing. The sinker makes the bottom of the fishing net body sink into the water, preventing the target organisms from escaping from the bottom, while ensuring that the net body is expanded vertically.

[0006] The warp sensing belt assembly includes a composite film made of carbon nanotubes and silicone rubber, which is laid along the warp direction of the net rope and has a built-in serpentine silver nanowire electrode. The weft sensing fiber assembly includes a fiber Bragg grating embedded in a PU elastic matrix. A composite film made of elastic silicone rubber as the substrate and coated with a carbon nanotube conductive network on the surface senses strain through the piezoresistive effect, realizing the structural characteristics of the flexible substrate and reducing the bending radius of the sensing device to ten millimeters. This greatly increases the number of high-frequency bending times that the device can withstand when trawling the fishing net. A miniature fiber grating with a spacing of five millimeters is integrated on the flexible substrate, and the grating size is reduced to two millimeters through ultraviolet etching technology. Combined with the continuous response of the carbon nanotube sensing layer, it can detect extremely small tears. Silver nanowire electrodes are used to enhance the conductivity of the flexible substrate. Utilizing their good conductivity and sensitivity to environmental changes, they can sense the stress and stretching of the fishing net body.

[0007] The PU elastic matrix can protect the fiber Bragg grating and give it good flexibility and elastic deformation ability, so that it can maintain the stability of the optical signal at a small bending radius. The weft sensing fiber component and the warp sensing belt component cooperate to form a two-dimensional sensing network, which can collaboratively and comprehensively sense the force and deformation of the fishing net body in the water, and realize accurate perception of contact pressure, position, sliding and other information.

[0008] The mesh-level sensor node assembly includes an annular elastic buffer groove, a metal bellows, a locking steel rope, a locking mesh rope, a woven frame and a micro-flexible sensing unit. The woven frame is made of high-strength Kevlar fiber. The annular elastic buffer groove is arranged on one side of the cross node of the woven frame. The elastic buffer groove is embedded in the metal bellows and locked to the woven frame by the locking steel rope. The micro-flexible sensing unit is embedded inside the metal bellows.

[0009] High-strength Kevlar fiber is used as the supporting skeleton to form a flexible network with warp and weft crossed according to the weaving rules of the fishing net, which greatly improves the integrity of the flexible sensing device and has good firmness. The metal bellows is fixed to the elastic buffer groove by locking steel ropes, which can protect the micro flexible sensing unit and prevent the optical fiber from being worn by the interlaced friction of the warp and weft lines of the fishing net. At the same time, the metal bellows can use its own corrugated structure to elastically deform, absorb and disperse concentrated stress, and avoid stress directly acting on the optical fiber, resulting in grating wavelength drift error.

[0010] Furthermore, a number of floats are equidistantly attached to the upper steel rope, and a number of sinkers are provided on the lower steel rope. The warp rope and the longitudinal rope are cross-connected and perpendicular to each other. The floats are connected to the steel rope through float steel, and the sinkers are penetrated by the steel rope. The braided frame structure is arranged in a one-to-one correspondence with the warp rope and the longitudinal rope of the fishing net body, and the micro flexible sensing unit is electrically connected to the warp sensing belt assembly and the weft sensing fiber assembly.

[0011] Furthermore, the composite film is symmetrically arranged on one side of the warp rope, the PU elastic matrix is ​​provided with a spiral groove, and the optical fiber Bragg grating is embedded in the spiral groove and arranged in a spiral structure.

[0012] The fiber Bragg grating is spirally embedded in the PU elastic matrix, which increases the perceptual sensitivity per unit area of ​​the fiber Bragg grating and improves the sensing accuracy.

[0013] Furthermore, the micro flexible sensing unit includes a barium titanate piezoelectric nanofiber membrane, a graphene film and a micro silver wire. The barium titanate piezoelectric nanofiber membrane and the graphene film are embedded in the metal bellows, the barium titanate piezoelectric nanofiber membrane is arranged on the inner side, and the graphene film is arranged on the outer side. The composite film abuts the metal bellows, and the PU elastic matrix abuts the outer side of the composite film.

[0014] Barium titanate piezoelectric nanofiber membrane utilizes the piezoelectric effect. When subjected to external impact and vibration, the electric dipole inside the barium titanate piezoelectric nanofiber membrane changes, resulting in polarization, and charges accumulate on the surface of the membrane, thereby converting mechanical energy into electrical signals and realizing sensitive detection of impact vibration.

[0015] Furthermore, the barium titanate piezoelectric nanofiber membrane, graphene film, composite film and optical fiber Bragg grating are electrically connected through micro silver wires, the interwoven nodes of the braided frame are tied and fixed to the composite film and the PU elastic matrix through locking net ropes, and the braided frame is adhered to one side of the fishing net body with waterproof glue.

[0016] The graphene film is based on the piezoresistive effect. When the fishing net is locally deformed, the graphene piezoresistive film will also deform accordingly, which will cause the conductive path of the graphene to change, and then the resistance value of the film to change. The barium titanate piezoelectric nanofiber membrane and the graphene film will electrically transmit the received change signals to the fiber grating through micro silver wires, thereby sensing the local deformation of the fishing net. Each cross node of the fishing net body is equipped with a flexible sensing unit for real-time monitoring, which greatly improves the positioning accuracy of the broken fishing net and realizes the rapid positioning of the specific position.

[0017] Furthermore, the bionic flexible support component includes several porous support frames, one end of the porous support frame is connected to the composite film, and the other end is connected to the woven frame. Fixed ropes are provided on both sides of the porous support frame, and the fixed ropes pass through the porous support frame and the composite film and are locked with the woven frame. The porous support frame is made of polylactic acid and is biomimetic in the form of a coral branch structure.

[0018] The porous support frame can provide support between the composite film and the woven frame to ensure the stability of the structure. The coral branch structure further enhances the support strength. At the same time, the porous structure has a certain degree of flexibility and elasticity. When the fishing net is subjected to external force, it can better adapt to deformation and evenly transfer stress to the entire structure, avoiding stress concentration in certain local areas, thereby protecting sensitive components such as fiber gratings from the influence of excessive stress and improving the accuracy and stability of sensing.

[0019] Furthermore, the electrical signal transmission component includes a shape memory alloy wire and an elastic microchannel, the elastic microchannel is filled with liquid metal LM, the shape memory alloy wire is embedded in the elastic microchannel, and the elastic microchannel is embedded on one side of the steel rope.

[0020] Furthermore, the elastic microchannel is electrically connected to a controller, the controller is provided with a display screen, and the controller is electrically connected to a fiber Bragg grating.

[0021] The shape memory alloy wire is made of nickel-titanium alloy. When the fishing net is damaged and the tension is abnormal, the mechanical stress causes the alloy wire to reach the phase transition temperature and then shrink. The deformation causes the elastic microchannel wrapped around it to deform. Due to the good conductivity of liquid metal LM, the deformation will change the electrical properties in the microchannel, generating an electrical signal. The electrical signal is fed back to the controller, which analyzes whether the strain corresponding to the electrical signal exceeds the threshold. If the threshold is exceeded, the wavelength scanning of the fiber Bragg grating is triggered to start self-detection.

[0022] Furthermore, a signal discrimination component is provided on the back side of the braided frame, and the signal discrimination component includes a packaging box, a cable, a MEMS acceleration sensor, a miniature hydrophone, a stainless steel hoop, and a processor. The intersection of the braided frame fits the back side of the packaging box and is fixed by micro screws. The MEMS acceleration sensor and the miniature hydrophone are encapsulated inside the packaging box by polyurethane glue.

[0023] Furthermore, the cable is electrically connected to adjacent packaging boxes, the cable is fixed to the braided frame through a stainless steel hoop, the processor is electrically connected to the cable and the controller, and the processor has an ADC chip and a wavelet packet transform chip built in.

[0024] When the fishing net is in an area with a large number of fish, the instantaneous strain signal generated when the fish hit the fishing net is similar to the damage and tearing signal characteristics, which can easily lead to false alarms; a signal discrimination component is added to one side of the woven frame. When the flexible sensing layer detects strain changes, the MEMS accelerometer and the micro hydrophone receive the strain data. The strain data is transmitted to the processor via a cable, and the acceleration and sound pressure signals are synchronously used by the ADC chip. The processed acceleration waveform will be displayed on the display. When the unidirectional acceleration peak perpendicular to the fishing net is greater than ten g, it can be judged as a fish impact, while the tearing deformation parallel to the fishing net is a multi-directional strain coupling with a smaller peak value. At the same time, the wavelet packet transform chip decomposes the frequency band energy of the signal in real time. The low frequency band corresponds to fish impact, and the high frequency band corresponds to fiber tearing.

[0025] Compared with the existing technology, the present invention provides a fishing net damage detection and positioning device based on flexible sensing, which has the following beneficial effects: 1. This fishing net damage detection and positioning device based on flexible sensing reduces the bending radius of the sensing device to ten millimeters through a flexible substrate. It can withstand high-frequency bending during fishing net trawling, and has a low signal attenuation rate.

[0026] 2. This fishing net damage detection and positioning device based on flexible sensing significantly reduces stress concentration at the nodes through elastic buffer grooves, and the carbon nanotube sensing layer isolates friction through the elastic base, greatly increasing its service life.

[0027] 3. This fishing net damage detection and positioning device based on flexible sensing can detect changes in tiny spacing tears through the continuous response of the microstructured grating spacing and the carbon nanotube sensing layer, greatly reducing the missed detection rate.

[0028] 4. This fishing net damage detection and positioning device based on flexible sensing achieves accurate positioning of the damaged position through a differential positioning algorithm combined with a dense array of flexible sensing units. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic diagram of the overall structure of the front side of the present invention; Figure 2 Schematic diagram of the flexible sensing layer structure of the present invention; Figure 3 This is a schematic diagram of the structure of the fishing net body of the present invention; Figure 4 Schematic diagram of the structure of the meridian sensor belt assembly of the present invention; Figure 5 Schematic diagram of the structure of the weft sensing fiber assembly of the present invention; Figure 6 This is a schematic diagram of the mesh-level sensor node assembly structure of the present invention; Figure 7Schematic diagram of the micro flexible sensing unit structure of the present invention; Figure 8 This is a schematic structural diagram of the bionic flexible support component of the present invention; Figure 9 This is a schematic structural diagram of the electrical signal transmission component of the present invention; Figure 10 Schematic diagram of the signal discrimination component structure of the present invention.

[0030] In the figure: 1. Fishing net body; 2. Steel rope; 3. Warp-direction sensing belt assembly; 4. Weft-direction sensing fiber assembly; 5. Mesh-level sensing node assembly; 6. Bionic flexible support assembly; 7. Electrical signal transmission assembly; 11. Warp-direction net rope; 12. Longitudinal net rope; 13. Float; 14. Sinker; 141. Float steel; 31. Composite film; 32. Snake-shaped silver nanowire electrode; 41. Fiber Bragg grating; 42. PU elastic matrix; 43. Spiral groove; 51. Annular elastic buffer groove; 52. Metal bellows; 53. Locking steel rope; 54. 4. Locking net rope; 55. Braided frame; 56. Barium titanate piezoelectric nanofiber membrane; 57. Graphene film; 58. Micro silver wire; 61. Porous support frame; 62. Fixing rope; 71. Shape memory alloy wire; 72. Elastic microchannel; 73. Controller; 74. Display; 8. Signal discrimination component; 81. Packaging box; 82. Cable; 83. MEMS accelerometer; 84. Micro hydrophone; 85. Stainless steel hoop; 86. Processor; 861. ADC chip; 862. Wavelet packet transform chip. DETAILED DESCRIPTION

[0031] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts are within the scope of protection of the present invention. Example 1

[0032] See also Figures 1-9 A fishing net damage detection and positioning device based on flexible sensing includes a fishing net body 1 and steel ropes 2 provided at the upper and lower ends of the fishing net body 1. A plurality of equally spaced warp sensing belt assemblies 3 are provided on one side of the fishing net body 1. A plurality of weft sensing fiber assemblies 4 are equally spaced and perpendicular to the warp sensing belt assemblies 3. A mesh-level sensing node assembly 5 is provided at the intersection of the warp sensing belt assembly 3 and the weft sensing fiber assemblies 4. A plurality of bionic flexible support assemblies 6 are provided between the warp sensing belt assembly 3 and the weft sensing fiber assemblies 4. An electrical signal transmission assembly 7 is provided at the edge of the fishing net body 1. The fishing net body 1 includes a warp rope 11 and a longitudinal rope 12. The warp rope 11 is connected to a steel rope 2 at both ends. A plurality of floats 13 are evenly spaced on the upper steel rope 2, and a plurality of sinkers 14 are provided on the lower steel rope 2. The float 13 keeps the fishing net body 1 on the water surface or at a specific depth, maintaining the shape of the net body and facilitating fishing. The sinker 14 sinks the bottom of the fishing net body 1 into the water to prevent target organisms from escaping from the bottom and ensures that the net body is vertically expanded.

[0033] The warp sensing belt assembly 3 includes a composite film 31 made of carbon nanotubes and silicone rubber. The composite film 31 is laid along the warp rope 11 and has a built-in serpentine silver nanowire electrode 32. The weft sensing fiber assembly 4 includes a fiber Bragg grating 41 embedded in a PU elastic matrix 42. A composite film 31 made of an elastic silicone rubber substrate and coated with a carbon nanotube conductive network is used to sense strain through the piezoresistive effect, realizing the structural characteristics of the flexible substrate. The bending radius limit of the sensing device is reduced to ten millimeters, thereby greatly improving the number of high-frequency bending times that the device can withstand when trawling the fishing net. A micro-fiber Bragg grating with a spacing of five millimeters is integrated on the flexible substrate, and the grating size is reduced to two millimeters through ultraviolet etching technology. Combined with the continuous response of the carbon nanotube sensing layer, it can detect extremely small tears. The silver nanowire electrode 32 is used to improve the conductivity of the flexible substrate. Utilizing its good conductivity and sensitivity to environmental changes, it can sense the stress and stretching degree of the fishing net body 1.

[0034] The PU elastic matrix 42 can protect the optical fiber Bragg grating 41 and give it good flexibility and elastic deformation ability, so that it can maintain the stability of the optical signal at a smaller bending radius. The weft sensing fiber component 4 and the warp sensing belt component 3 cooperate to form a two-dimensional sensing network, which can collaboratively and comprehensively sense the force and deformation of the fishing net body 1 in the water, and realize accurate perception of contact pressure, position, sliding and other information.

[0035] The mesh-level sensor node assembly 5 includes an annular elastic buffer groove 51, a metal bellows 52, a locking steel rope 53, a locking net rope 54, a braided frame 55 and a micro-flexible sensor unit. The braided frame 55 is made of high-strength Kevlar fiber. The braided frame 55 structure is arranged in a one-to-one correspondence with the warp net rope 11 and the longitudinal net rope 12 of the fishing net body 1. The annular elastic buffer groove 51 is arranged on one side of the cross node of the braided frame 55. The elastic buffer groove 51 is embedded in the metal bellows 52 and locked to the braided frame 55 through the locking steel rope 53. The micro-flexible sensor unit is embedded in the inner side of the metal bellows 52. The micro-flexible sensor unit is electrically connected to the warp sensor belt assembly 3 and the weft sensor fiber assembly 4.

[0036] High-strength Kevlar fiber is used as the supporting skeleton to form a flexible network with warp and weft crossed according to the weaving rules of the fishing net, which greatly improves the integrity of the flexible sensing device and has good firmness. The metal bellows 52 is fixed to the elastic buffer groove 51 by the locking steel rope 53, which can protect the micro flexible sensing unit and prevent the optical fiber from being worn by the interlaced friction of the warp and weft lines of the fishing net. At the same time, the metal bellows 52 can use its own corrugated structure to elastically deform, absorb and disperse concentrated stress, and avoid stress directly acting on the optical fiber, resulting in grating wavelength drift error.

[0037] Furthermore, the warp net rope 11 and the longitudinal net rope 12 are cross-connected and perpendicular to each other, the float 13 is connected to the steel rope 2 through the float steel 141, and the sinker 14 is penetrated by the steel rope 2.

[0038] Furthermore, the composite film 31 is symmetrically arranged on one side of the warp rope 11 , the PU elastic matrix 42 is provided with a spiral groove 43 , and the fiber grating 41 is embedded in the spiral groove 43 and arranged in a spiral structure.

[0039] The fiber Bragg grating 41 is spirally embedded in the PU elastic matrix 42, which increases the perceptual sensitivity per unit area of ​​the fiber Bragg grating and improves the sensing accuracy.

[0040] Furthermore, the micro flexible sensing unit includes a barium titanate piezoelectric nanofiber membrane 56, a graphene film 57 and a micro silver wire 58. The barium titanate piezoelectric nanofiber membrane 56 and the graphene film 57 are embedded in the metal bellows 52. The barium titanate piezoelectric nanofiber membrane 56 is arranged on the inner side, and the graphene film 57 is arranged on the outer side. The composite film 31 abuts the metal bellows 52, and the PU elastic matrix 42 abuts the outer side of the composite film 31.

[0041] The barium titanate piezoelectric nanofiber membrane 56 utilizes the piezoelectric effect. When subjected to external impact and vibration, the electric dipole inside the barium titanate piezoelectric nanofiber membrane changes, resulting in polarization, and charges are accumulated on the surface of the membrane, thereby converting mechanical energy into electrical signals, realizing sensitive detection of impact vibration.

[0042] Furthermore, the barium titanate piezoelectric nanofiber membrane 56, the graphene film 57, the composite film 31 and the optical fiber Bragg grating 41 are electrically connected through micro silver wires 58, the interwoven nodes of the braided frame 55 are tied and fixed to the composite film 31 and the PU elastic matrix 42 by locking net ropes 54, and the braided frame 55 is adhered to one side of the fishing net body 1 by waterproof glue.

[0043] The graphene film 57 is based on the piezoresistive effect. When the fishing net is locally deformed, the graphene piezoresistive film also deforms accordingly, which causes the conductive path of the graphene to change, and then the resistance value of the film to change. The barium titanate piezoelectric nanofiber membrane 56 and the graphene film 57 electrically transmit the received change signal to the fiber grating 41 through the micro silver wire 58, thereby sensing the local deformation of the fishing net. Each cross node of the fishing net body 1 is equipped with a corresponding flexible sensing unit for real-time monitoring, which greatly improves the positioning accuracy of the broken fishing net and realizes rapid positioning of the specific position.

[0044] Furthermore, the bionic flexible support component 6 includes several porous support frames 61, one end of the porous support frame 61 is connected to the composite film 31, and the other end is connected to the woven frame 55. Fixed ropes 62 are provided on both sides of the porous support frame 61. The fixed ropes 62 pass through the porous support frame 61 and the composite film 31 and are locked with the woven frame 55. The porous support frame 61 is made of polylactic acid and has a bionic coral branch structure.

[0045] The porous support frame 61 can provide support between the composite film 31 and the braided frame 55 to ensure the stability of the structure. The coral branch structure further enhances the support strength. At the same time, the porous structure has a certain degree of flexibility and elasticity. When the fishing net is subjected to external force, it can better adapt to deformation and evenly transfer stress to the entire structure to avoid stress concentration in certain local areas, thereby protecting sensitive components such as optical fiber Bragg gratings from the influence of excessive stress and improving the accuracy and stability of sensing.

[0046] Furthermore, the electrical signal transmission component 7 includes a shape memory alloy wire 71 and an elastic microchannel 72 . The elastic microchannel 72 is filled with liquid metal LM. The shape memory alloy wire 71 is embedded in the elastic microchannel 72 , and the elastic microchannel 72 is embedded on one side of the steel rope 2 .

[0047] Furthermore, the elastic microchannel 72 is electrically connected to a controller 73 . The controller 73 is provided with a display screen 74 . The controller 73 is electrically connected to the fiber Bragg grating 41 .

[0048] The shape memory alloy wire 71 is a nickel-titanium alloy. When the fishing net is damaged and the tension is abnormal, the mechanical stress causes the alloy wire to reach the phase transition temperature and then shrink. The deformation causes the elastic microchannel 72 wrapped around it to deform. Due to the good conductivity of the liquid metal LM, the deformation will change the electrical characteristics in the microchannel and generate an electrical signal. The electrical signal is fed back to the controller 73. The controller 73 analyzes whether the strain corresponding to the electrical signal exceeds the threshold. When the threshold is exceeded, the wavelength scanning of the fiber Bragg grating 41 is triggered to start self-detection. Example 2

[0049] See also Figure 10The difference between the second embodiment and the first embodiment is that a signal discrimination component 8 is provided on the back side of the braided frame 55. The signal discrimination component 8 includes a packaging box 81, a cable 82, a MEMS acceleration sensor 83, a micro hydrophone 84, a stainless steel hoop 85, and a processor 86. The intersection of the braided frame 55 is attached to the back side of the packaging box 81 and fixed by micro screws. The MEMS acceleration sensor 83 and the micro hydrophone 84 are encapsulated inside the packaging box 81 by polyurethane glue.

[0050] The cable 82 is electrically connected to the adjacent packaging box 81 and fixed to the braiding frame 55 through the stainless steel hoop 85 . The processor 86 is electrically connected to the cable 82 and the controller 73 . The processor 86 has an ADC chip 861 and a wavelet packet transform chip 862 built in.

[0051] When a fishing net is located in an area with a large number of fish, the instantaneous strain signal generated by the fish impacting the net has characteristics similar to those of damage and tearing, which can easily lead to false alarms. Therefore, a signal discrimination component 8 is added to one side of the braided frame 55. When the flexible sensing layer detects a strain change, the MEMS accelerometer 83 and the micro-hydrophone 84 receive the strain data. This data is transmitted via cable 82 to the processor 86. The ADC chip 861 simultaneously processes the acceleration and sound pressure signals, and the resulting acceleration waveform is displayed on the display 74. A unidirectional acceleration peak greater than 10 g perpendicular to the net is considered a fish impact, while a tearing deformation parallel to the net is a multi-directional strain coupling with a smaller peak. Simultaneously, a wavelet packet transform chip 862 decomposes the signal's frequency band energy in real time, with low frequencies corresponding to fish impact and high frequencies to fiber tearing.

[0052] The specific usage and function of this embodiment are as follows: During use, the controller 73 and processor 86 are first placed on a vessel, and the fishing net body 1 is placed in the water. The float 13 keeps the fishing net body 1 at the water surface or a specific depth, maintaining the shape of the net body and facilitating fishing. The sinker 14 sinks the bottom of the fishing net body 1 into the water to prevent target organisms from escaping from the bottom, while ensuring that the net body is vertically deployed. The shape memory alloy wire 71 is made of nickel-titanium alloy. When the fishing net is damaged and abnormal tension occurs, mechanical stress causes the alloy wire to reach a phase transition temperature, causing it to shrink. This deformation causes the elastic microchannel 72 surrounding it to deform. Due to the excellent conductivity of the liquid metal LM, this deformation changes the electrical properties within the microchannel, generating an electrical signal. This electrical signal is fed back to the controller 73, which analyzes whether the strain corresponding to the electrical signal exceeds a threshold. If the threshold is exceeded, the controller triggers the wavelength scanning of the fiber Bragg grating 41 to begin self-detection. The barium titanate piezoelectric nanofiber membrane 56 utilizes the piezoelectric effect. When subjected to external impact and vibration, the electric dipole inside the barium titanate piezoelectric nanofiber membrane changes, generating polarization and collecting charge on the membrane surface, thereby converting mechanical energy into an electrical signal and realizing sensitive detection of impact and vibration. The graphene film 57 is based on the piezoresistive effect. When the fishing net is locally deformed, the graphene piezoresistive film also deforms, which causes the conductive path of the graphene to change, thereby changing the resistance value of the film. The barium titanate piezoelectric nanofiber membrane 56 and the graphene film 57 electrically transmit the received change signal to the fiber Bragg grating 41 through the micro silver wire 58. When the signal returned by the fiber Bragg grating 41 shows that the resistance change rate of the flexible sensing unit in a certain area is greater than 20% and the grating wavelength offset of the adjacent flexible sensing units is greater than three picometers, the controller 73 calculates the approximate coordinates of the damaged area through a differential algorithm, and uses the sensitive detection of the barium titanate piezoelectric nanofiber membrane 56 to further narrow the coordinate area and display it on the display screen 74. Each cross node of the fishing net body 1 is equipped with a corresponding flexible sensing unit for real-time monitoring, which greatly improves the positioning accuracy of the broken fishing net and realizes rapid positioning of the specific position.

[0053] A composite film 31 made of an elastic silicone rubber substrate and coated with a carbon nanotube conductive network is used to sense strain through the piezoresistive effect, realizing the structural characteristics of the flexible substrate. The bending radius limit of the sensing device is reduced to ten millimeters, thereby greatly improving the number of high-frequency bending times that the device can withstand when trawling the fishing net. A micro-fiber Bragg grating with a spacing of five millimeters is integrated on the flexible substrate, and the grating size is reduced to two millimeters through ultraviolet etching technology. Combined with the continuous response of the carbon nanotube sensing layer, it can detect extremely small tears. The silver nanowire electrode 32 is used to improve the conductivity of the flexible substrate. Utilizing its good conductivity and sensitivity to environmental changes, it can sense the stress and stretching degree of the fishing net body 1.

[0054] The PU elastic matrix 42 can protect the optical fiber Bragg grating 41 and give it good flexibility and elastic deformation ability, so that it can maintain the stability of the optical signal at a smaller bending radius. The weft sensing fiber component 4 and the warp sensing belt component 3 cooperate to form a two-dimensional sensing network, which can collaboratively and comprehensively sense the force and deformation of the fishing net body 1 in the water, and realize accurate perception of contact pressure, position, sliding and other information.

[0055] High-strength Kevlar fiber is used as the supporting skeleton to form a flexible network with warp and weft crossed according to the weaving rules of the fishing net, which greatly improves the integrity of the flexible sensing device and has good firmness. The metal bellows 52 is fixed to the elastic buffer groove 51 by the locking steel rope 53, which can protect the micro flexible sensing unit and prevent the optical fiber from being worn by the interlaced friction of the warp and weft lines of the fishing net. At the same time, the metal bellows 52 can use its own corrugated structure to elastically deform, absorb and disperse concentrated stress, and avoid stress directly acting on the optical fiber, resulting in grating wavelength drift error.

[0056] When the fishing net is in an area with a large number of fish, the instantaneous strain signal generated when the fish hit the fishing net is similar to the damage and tearing signal characteristics, which can easily lead to false alarms. A signal identification component 8 is added to one side of the braided frame 55. When the flexible sensing layer detects the strain change, the MEMS acceleration sensor 83 and the micro hydrophone 84 receive the strain data. The strain data is transmitted to the processor 86 via the cable 82. The acceleration and sound pressure signals are synchronously used by the ADC chip 861. The processed acceleration waveform will be displayed on the display screen 74. When the unidirectional acceleration peak perpendicular to the fishing net is greater than ten g, it can be judged as a fish impact, while the tearing deformation parallel to the fishing net is a multi-directional strain coupling with a smaller peak value. At the same time, the wavelet packet transform chip 862 decomposes the frequency band energy of the signal in real time. The low frequency band corresponds to the impact of the fish school, and the high frequency band corresponds to the fiber tearing.

[0057] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A fishing net damage detection and positioning device based on flexible sensing, comprising a fishing net body (1) and steel ropes (2) provided at the upper and lower ends of the fishing net body (1), characterized in that: A plurality of warp sensing belt assemblies (3) are provided on one side of the fishing net body (1), a plurality of weft sensing fiber assemblies (4) are provided at equal intervals in a direction perpendicular to the warp sensing belt assemblies (3), a mesh-level sensing node assembly (5) is provided at the intersection of the warp sensing belt assemblies (3) and the weft sensing fiber assemblies (4), a plurality of bionic flexible support assemblies (6) are provided between the warp sensing belt assemblies (3) and the weft sensing fiber assemblies (4), and an electrical signal transmission assembly (7) is provided on the edge of the fishing net body (1); The fishing net body (1) comprises a warp rope (11) and a longitudinal rope (12), and both ends of the warp rope (11) are connected to steel ropes (2); The longitudinal sensing belt assembly (3) includes a composite film (31), the composite film (31) is made of carbon nanotubes and silicone rubber, the composite film (31) is laid along the longitudinal direction of the net rope (11), and the composite film (31) has a built-in serpentine silver nanowire electrode (32). The latitudinal sensing fiber assembly (4) includes a fiber Bragg grating (41), and the fiber Bragg grating (41) is embedded in a PU elastic matrix (42); The mesh-level sensor node assembly (5) includes an annular elastic buffer groove (51), a metal bellows (52), a locking steel rope (53), a locking mesh rope (54), a braided frame (55) and a micro-flexible sensor unit. The braided frame (55) is made of high-strength Kevlar fiber. The annular elastic buffer groove (51) is arranged on one side of the cross node of the braided frame (55). The elastic buffer groove (51) is embedded in the metal bellows (52) and locked on the braided frame (55) by the locking steel rope (53). The micro-flexible sensor unit is embedded inside the metal bellows (52).

2. The fishing net damage detection and positioning device based on flexible sensing according to claim 1, characterized in that: The warp rope (11) and the longitudinal rope (12) are cross-connected and perpendicular to each other; the float (13) is connected to the steel rope (2) through the float steel (141); the sinker (14) is penetrated by the steel rope (2); the braided frame (55) structure is arranged in a one-to-one correspondence with the warp rope (11) and the longitudinal rope (12) of the fishing net body (1); and the micro-flexible sensing unit is electrically connected to the warp sensing belt assembly (3) and the weft sensing fiber assembly (4).

3. The fishing net damage detection and positioning device based on flexible sensing according to claim 2, characterized in that: A plurality of floats (13) are equidistantly attached to the upper steel rope (2), and a plurality of sinkers (14) are provided on the lower steel rope (2). The composite film (31) is symmetrically arranged on one side of the warp rope (11). The PU elastic matrix (42) is provided with a spiral groove (43), and the optical fiber Bragg grating (41) is embedded in the spiral groove (43) and is arranged in a spiral structure.

4. The fishing net damage detection and positioning device based on flexible sensing according to claim 3, characterized in that: The micro flexible sensing unit includes a barium titanate piezoelectric nanofiber membrane (56), a graphene film (57) and a micro silver wire (58), wherein the barium titanate piezoelectric nanofiber membrane (56) and the graphene film (57) are embedded in the metal bellows (52), the barium titanate piezoelectric nanofiber membrane (56) is arranged on the inner side, and the graphene film (57) is arranged on the outer side thereof, the composite film (31) abuts the metal bellows (52), and the PU elastic matrix (42) abuts the outer side of the composite film (31).

5. The fishing net damage detection and positioning device based on flexible sensing according to claim 4, characterized in that: The barium titanate piezoelectric nanofiber film (56), the graphene film (57), the composite film (31) and the optical fiber Bragg grating (41) are electrically connected via micro silver wires (58); the interwoven nodes of the braided frame (55) are bound and fixed to the composite film (31) and the PU elastic matrix (42) via locking net ropes (54); and the braided frame (55) is adhered to one side of the fishing net body (1) via waterproof glue.

6. The fishing net damage detection and positioning device based on flexible sensing according to claim 1, characterized in that: The bionic flexible support assembly (6) comprises a plurality of porous support frames (61), one end of the porous support frame (61) is connected to the composite film (31), and the other end is connected to the braided frame (55), and fixing ropes (62) are provided on both sides of the porous support frame (61), and the fixing ropes (62) pass through the porous support frame (61) and the composite film (31) and are locked with the braided frame (55), and the porous support frame (61) is made of polylactic acid and has a bionic coral branch structure.

7. The fishing net damage detection and positioning device based on flexible sensing according to claim 1, characterized in that: The electrical signal transmission component (7) comprises a shape memory alloy wire (71) and an elastic microchannel (72), wherein the elastic microchannel (72) is filled with liquid metal LM, the shape memory alloy wire (71) is embedded in the elastic microchannel (72), and the elastic microchannel (72) is embedded on one side of the steel rope (2).

8. The fishing net damage detection and positioning device based on flexible sensing according to claim 7, characterized in that: The elastic microchannel (72) is electrically connected to a controller (73), the controller (73) is provided with a display screen (74), and the controller (73) is electrically connected to a fiber grating (41).

9. The fishing net damage detection and positioning device based on flexible sensing according to claim 6, characterized in that: A signal discrimination component (8) is provided on the back side of the braided frame (55), and the signal discrimination component (8) includes a packaging box (81), a cable (82), a MEMS acceleration sensor (83), a micro hydrophone (84), a stainless steel hoop (85), and a processor (86). The intersection of the braided frame (55) fits the back side of the packaging box (81) and is fixed by micro screws. The MEMS acceleration sensor (83) and the micro hydrophone (84) are encapsulated inside the packaging box (81) by polyurethane glue.

10. The fishing net damage detection and positioning device based on flexible sensing according to claim 9, characterized in that: The cable (82) is electrically connected to adjacent packaging boxes (81), the cable (82) is fixed to the braided frame (55) through a stainless steel hoop (85), the processor (86) is electrically connected to the cable (82) and the controller (73), and the processor (86) has an ADC chip (861) and a wavelet packet transform chip (862) built in.

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