A synthetic aperture side-scan sonar device conformally designed with an unmanned surface vessel (USV) and the USV.

Abstract

This invention discloses a synthetic aperture side-scan sonar device and an unmanned surface vessel (USV) with a conformal design, relating to the field of USV technology. The synthetic aperture side-scan sonar device is used in USVs with hull-mounted receiving slots. Specifically, it includes a synthetic aperture sonar array assembly and a sonar electronics box. The synthetic aperture sonar array assembly comprises two synthetic aperture sonar arrays, located on opposite sides of the USV and embedded within the receiving slots in the hull. The receiving slot has a mounting surface for installing the synthetic aperture sonar arrays, parallel to the central axis of the USV. The sonar electronics box is located inside the USV's cabin and is connected to the two synthetic aperture sonar arrays for signal transmission. The synthetic aperture side-scan sonar device provided by this invention can be integrated with the USV, without affecting the hull's speed or navigation safety, while ensuring stable and reliable sonar performance.

Description

Technical Field

[0001] This invention relates to the field of unmanned surface vessel (USV) technology, and specifically to a synthetic aperture side-scan sonar device and USV that are conformally designed with USV. Background Technology

[0002] Synthetic aperture sonar is a high-resolution underwater imaging device that uses the movement of a small aperture array to create an equivalent large aperture. It has high imaging accuracy and long detection range, and is widely used in marine surveying, underwater target detection, seabed topography imaging and other scenarios.

[0003] Currently, traditional sonar arrays are limited by their long dimensions, inflexibility, the need for stable and secure installation, and the requirements for high-speed hull movement, making direct mounting on the hull plating difficult. They are typically secured using external brackets. This method causes the brackets and sonar to protrude beyond the hull, disrupting the hull's lines, increasing drag, and affecting high-speed performance. It also easily leads to exceeding the hull width limit, posing a significant safety hazard. Furthermore, external brackets have lower installation precision, making it difficult to ensure the sonar array's attitude stability. They are susceptible to interference from water currents and air bubbles, affecting image quality. Moreover, repeated disassembly and reassembly are required for use at sea, making operation cumbersome and inconvenient.

[0004] Therefore, the sonar devices currently carried by unmanned surface vessels (USVs) have technical problems such as affecting the speed and navigation safety of the vessel and reducing the performance of the sonar. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned technical deficiencies and propose a synthetic aperture side-scan sonar device and unmanned surface vessel (USV) with conformal design, thereby solving the technical problem that the sonar installation structure of USVs affects the speed of the vessel, navigation safety and sonar performance.

[0006] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a synthetic aperture side-scan sonar device conformally designed for an unmanned surface vessel (USV). This device is used on USVs with accommodating slots in their hulls. Specifically, it includes a synthetic aperture sonar array assembly and a sonar electronics box. The synthetic aperture sonar array assembly comprises two synthetic aperture sonar arrays, located on opposite sides of the USV and embedded within the accommodating slots in the hull. The accommodating slot has a mounting surface for installing the synthetic aperture sonar arrays, parallel to the central axis of the USV. The sonar electronics box is located inside the USV's cabin and is connected to the two synthetic aperture sonar arrays via signal transmission.

[0007] In some embodiments, the synthetic aperture sonar array includes a transmitting array and a receiving array, with the transmitting array located at the front end of the receiving array, which is the end of the receiving array close to the bow of the unmanned surface vessel.

[0008] In some embodiments, the receiving array includes a front receiving array and a rear receiving array, with the front receiving array located between the transmitting array and the rear receiving array, and the transmitting array, the front receiving array, and the rear receiving array connected end to end in sequence.

[0009] In some embodiments, the hull bilge of the unmanned surface vessel is provided with a parallel midbody, the length of which is not less than 95% of the length of the synthetic aperture sonar array, and the parallel midbody is provided with a receiving slot for embedding the synthetic aperture sonar array.

[0010] In some embodiments, the synthetic aperture sonar array is fixedly mounted on the mounting surface of the receiving slot by fasteners, the synthetic aperture sonar array and the sonar electronics box are connected by cables, and a sealing structure is provided between the mounting surface and the synthetic aperture sonar array.

[0011] In some embodiments, the angle α1 between the central axis of the synthetic aperture sonar array and the horizontal plane satisfies -2°≤α1≤2°.

[0012] In some embodiments, the angle α2 between the central axis of the synthetic aperture sonar array and the vertical plane passing through the bow satisfies -2°≤α2≤2°.

[0013] In some embodiments, the angle α3 between the array surface normal of the synthetic aperture sonar array and the horizontal plane satisfies 28°≤α3≤32°.

[0014] In some embodiments, the sonar electronics box includes an air-cooled chassis with an air inlet on the lower surface and an air outlet on the upper surface.

[0015] Secondly, the present invention also provides an unmanned surface vessel (USV) comprising the aforementioned synthetic aperture side-scan sonar device.

[0016] Compared with existing technologies, this invention provides a synthetic aperture side-scan sonar device conformally designed for use with unmanned surface vessels (USVs). Two synthetic aperture sonar arrays are embedded into receiving slots on both sides of the USV hull, achieving conformal integrated installation that does not protrude from the hull or disrupt the hull's lines, thus improving navigation safety. Simultaneously, the synthetic aperture sonar arrays are stably mounted on the hull shell without affecting sonar performance. The mounting surface is parallel to the hull's centerline, ensuring the array's attitude and heading are consistent, improving imaging accuracy. The sonar electronics box is located inside the hull, providing stable signal transmission and good protection. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of an unmanned surface vessel (USV) with a synthetic aperture side-scan sonar device provided in an embodiment of the present invention. Figure 1 ; Figure 2 This is a schematic diagram of an unmanned surface vessel (USV) with a synthetic aperture side-scan sonar device provided in an embodiment of the present invention. Figure 2 ; Figure 3 This is a schematic diagram of the structure of a synthetic aperture sonar array provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the structural dimensions of the transmission array provided in the embodiment of the present invention. Figure 1 ; Figure 5 This is a schematic diagram of the structural dimensions of the transmission array provided in the embodiment of the present invention. Figure 2 ; Figure 6 This is a schematic diagram of the structural dimensions of the receiving array provided in an embodiment of the present invention. Figure 1 ; Figure 7 This is a schematic diagram of the structural dimensions of the receiving array provided in an embodiment of the present invention. Figure 2 ; Figure 8 This is a schematic diagram of the installation structure of the synthetic aperture sonar array provided in an embodiment of the present invention; Figure 9 This is a schematic diagram of the sonar transmission synchronization signal link connection provided in an embodiment of the present invention; Figure 10 This refers to the setting of the computational domain and boundary conditions for hull simulation provided in this embodiment of the invention. Figure 1 ; Figure 11 This refers to the setting of the computational domain and boundary conditions for hull simulation provided in this embodiment of the invention. Figure 2 ; Figure 12 This is a schematic diagram of the Overset mesh division for hull simulation provided in this embodiment of the invention; Figure 13 This is a schematic diagram of the computational domain cutting body mesh division for hull simulation provided in an embodiment of the present invention.

[0018] Explanation of reference numerals in the attached figures: 10. Unmanned surface vessel; 100. Synthetic Aperture Side-Scan Sonar Device; 110. Synthetic Aperture Sonar Array; 111. Transmitter Array; 112. Front Receiver Array; 113. Rear Receiver Array; 120. Sonar Electronics Box; 121. Air Inlet; 122. Air Outlet; 200. Hull; 210. Reservoir. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0020] Synthetic aperture sonar is a high-resolution underwater imaging device that uses the movement of a small-aperture array to create an equivalent large-aperture image. It boasts high imaging accuracy and long detection range, and is widely used in marine mapping, underwater target detection, and seabed topography imaging. However, current sonar devices mounted on unmanned surface vessels (USVs) suffer from technical problems that affect the vessel's speed and navigation safety, and reduce sonar performance.

[0021] To address the technical problem that the sonar installation structure of unmanned surface vessels (USVs) affects the speed, navigation safety, and sonar performance of the vessel, this invention provides a synthetic aperture side-scan sonar device that is conformally designed with the USV. This synthetic aperture side-scan sonar device can be integrated with the USV, without affecting the speed and navigation safety of the vessel, while ensuring stable and reliable sonar performance.

[0022] It should be noted that the synthetic aperture side-scan sonar device provided by the present invention is used in, but not limited to, high-speed unmanned surface vessels, planing boats, reconnaissance and detection boats, marine monitoring platforms and various underwater vehicles. For ease of explanation, this invention will only use the application of the synthetic aperture side-scan sonar device to a high-speed unmanned surface vessel as an example. The principle of the device applied to other types of navigation equipment is essentially the same as that applied to high-speed unmanned surface vessels, and will not be described in detail here.

[0023] This application provides a synthetic aperture side-scan sonar device 100 conformally designed for use with unmanned surface vessels, such as... Figure 1 and Figure 2 As shown, the synthetic aperture side-scan sonar device 100 is used in an unmanned surface vessel 10 with a receiving slot in its hull. Specifically, it includes a synthetic aperture sonar array assembly and a sonar electronics box 120. The synthetic aperture sonar array assembly includes two synthetic aperture sonar arrays 110, which are located on both sides of the unmanned surface vessel 10 and embedded in the receiving slots 210 of the hull 200. The receiving slots 210 have mounting surfaces for installing the synthetic aperture sonar arrays 110, and the mounting surfaces are parallel to the central axis of the unmanned surface vessel. The sonar electronics box 120 is located inside the cabin of the unmanned surface vessel 10 and is connected to the two synthetic aperture sonar arrays 110 for signal transmission.

[0024] The synthetic aperture sonar array 110 is a high-resolution underwater imaging technique that utilizes the movement of a small-aperture array to effectively form a large-aperture array. By coherently processing the received echo signals, it can achieve higher resolution and a longer detection range than traditional sonar.

[0025] The unmanned surface vessel 10 has receiving slots 210 on both sides of its hull 200. Each receiving slot 210 has a mounting surface for installing a synthetic aperture sonar array 110, and these mounting surfaces are parallel to the central axis of the unmanned surface vessel. The synthetic aperture sonar array 110 is symmetrically and horizontally installed in the receiving slots 210 on both sides of the unmanned surface vessel 10, thus integrating the synthetic aperture sonar array 110 with the unmanned surface vessel 10 into a conformal design. The specific installation requirements for the synthetic aperture sonar array 110 will be described later through embodiments and will not be described here.

[0026] The synthetic aperture sonar array 110 includes a transmitting array 111 and a receiving array, such as... Figure 3 As shown, the transmitting array 111, driven by an electrical signal, transmits acoustic detection signals underwater, forming an active detection beam that covers the target detection area. The receiving array is used to receive echo signals reflected from underwater targets or the seabed, convert the acoustic signals into electrical signals, and transmit them to the sonar electronics box 120 for processing, providing raw data for subsequent imaging and detection.

[0027] For example, the transmitting array 111 is located at the front end of the receiving array, with the front end being the end of the receiving array closest to the bow of the unmanned surface vessel 10. The structure and installation dimensions of the transmitting array 111 are as follows: Figure 4 and Figure 5 As shown; the structure and installation dimensions of the receiver array are as follows. Figure 6 and Figure 7 As shown, by placing the transmitting array 111 near the bow, the acoustic wave transmission and echo reception paths can be optimized, inter-array interference can be reduced, and the signal-to-noise ratio and resolution of synthetic aperture sonar imaging can be improved.

[0028] For example, such as Figure 3 As shown, the receiving array includes a front receiving array 112 and a rear receiving array 113. The front receiving array 112 is located between the transmitting array 111 and the rear receiving array 113. The transmitting array 111, the front receiving array 112, and the rear receiving array 113 are connected end-to-end in sequence. By adopting the structure of connecting the transmitting array 111, the front receiving array 112, and the rear receiving array 113 end-to-end in sequence, the effective receiving aperture is expanded, the imaging coverage and distance resolution are improved, and the system layout is compact and reasonable.

[0029] The power supply constraints and requirements of the synthetic aperture sonar array 110 can be determined according to actual needs. For example, the nominal input voltage of the synthetic aperture sonar array 110 is 48VDC, and the dynamic range of the input voltage is 46VDC-50VDC. The average power of the synthetic aperture sonar array 110 during operation is 180W. When the system is powered on, the peak power of the payload SAS (Synthetic Aperture Sonar) is 300W, lasting for approximately 20 seconds.

[0030] The sonar electronics box 120 is used to provide power supply, signal transmission control, echo signal reception, data acquisition and processing for the synthetic aperture sonar array 110, and transmit the processed detection data to the shipboard control system to realize underwater imaging and target detection functions.

[0031] like Figure 2 As shown, the sonar electronics box 120 is located inside the cabin of the unmanned surface vessel 10 and is connected to two composite aperture sonar arrays 110 via watertight cables. These connections include, but are not limited to, connections using watertight cables. For example, the two composite aperture sonar arrays 110 have a total of six watertight cables leading out, and the sonar electronics box 120 is connected to the transmitting array 111, the front receiving array 112, and the rear receiving array 113 of the two composite aperture sonar arrays 110 via these watertight cables.

[0032] In this embodiment, by embedding the two synthetic aperture sonar arrays 110 into the receiving slots 210 on both sides of the hull of the unmanned surface vessel 10, conformal integrated installation is achieved, which does not protrude from the hull or disrupt the hull's lines, thus improving navigation safety. Simultaneously, the synthetic aperture sonar arrays 110 are stably installed on the outer shell of the hull 200 without affecting sonar performance. The mounting surface is parallel to the hull's central axis, ensuring the array's attitude and heading are consistent, improving imaging accuracy. The sonar electronics box is located inside the hull, providing stable signal transmission and good protection.

[0033] In some embodiments, the hull bilge of the unmanned surface vessel 10 is provided with a parallel midbody, the length of which is not less than 95% of the length of the synthetic aperture sonar array 110, and the parallel midbody is provided with a receiving slot 210 for embedding the synthetic aperture sonar array 110.

[0034] In this embodiment, the unmanned surface vessel 10 has a parallel midbody structure at the bilge position. This parallel midbody is a region of the bilge with a straight profile and a basically unchanged cross-sectional shape, providing a flat and continuous mounting surface for the synthetic aperture sonar array 110. To ensure that the sonar array is installed stably and as a whole in the straight region, and to avoid warping or deformation of the array due to hull profile contraction or bending, the length of the parallel midbody is not less than 95% of the length of the synthetic aperture sonar array. For example, the length of the parallel midbody can be equal to or greater than the length of the synthetic aperture sonar array 110, so that the main body of the array can be reliably arranged in the straight section, ensuring the accuracy of the installation attitude. Meanwhile, a receiving slot 210 adapted to the shape of the synthetic aperture sonar array 110 is provided at the parallel midbody, which is used to embed the array into the hull and achieve conformal installation with the hull, so that the array does not protrude from the hull surface and does not disrupt the hull's streamline, thereby ensuring the speed and navigation safety of the unmanned surface vessel when it travels at high speed.

[0035] In some embodiments, the synthetic aperture sonar array 110 is fixedly mounted on the mounting surface of the receiving groove 210 by fasteners, the synthetic aperture sonar array 110 is connected to the sonar electronics box 120 by cables, and a sealing structure is provided between the mounting surface and the synthetic aperture sonar array 110.

[0036] In this embodiment, the synthetic aperture sonar array 110 and the sonar electronics box 120 inside the submarine are connected by a watertight cable for communication. The synthetic aperture sonar array 110 is fixed to the mounting surface by fasteners, including but not limited to screws. The watertight cable connected to the array passes through the mounting surface and interacts with the sonar electronics box 120 inside the submarine to exchange control signals and data signals. To effectively prevent water from seeping into the submarine through the mounting surface gap and cable penetration holes, and to improve the long-term reliability and safety of the system, a sealing structure is provided between the mounting surface and the synthetic aperture sonar array 110. This sealing structure is a watertight isolation structure, including but not limited to sealing colloids, sealing rings, etc.

[0037] In some embodiments, the angle α1 between the central axis of the synthetic aperture sonar array 110 and the horizontal plane satisfies -2°≤α1≤2° (not shown in the figure).

[0038] In this embodiment, the angle α1 between the central axis of the synthetic aperture sonar array 110 and the horizontal plane can specifically be -2°, -1°, 0°, 1°, 2°, or any value between two adjacent values ​​mentioned above. By controlling the angle between the central axis of the synthetic aperture sonar array 110 and the horizontal plane within ±2°, the horizontal attitude of the array is ensured, and the imaging geometric accuracy is improved.

[0039] In some embodiments, the angle α2 between the central axis of the synthetic aperture sonar array 110 and the vertical plane passing through the bow satisfies -2°≤α2≤2° (not shown in the figure).

[0040] In this embodiment, the vertical plane passing through the bow refers to the plane that passes through the foremost point of the bow and extends vertically upwards and downwards. The angle α2 between the central axis of the synthetic aperture sonar array 110 and the vertical plane passing through the bow can specifically be -2°, -1°, 0°, 1°, 2°, or any value between two adjacent values ​​mentioned above. By controlling the angle between the central axis of the synthetic aperture sonar array 110 and the hull's symmetry plane within ±2°, the array's pointing direction is ensured to be consistent with the heading, avoiding left and right skew that could cause image distortion and positioning errors.

[0041] In some embodiments, such as Figure 8 As shown, the angle α3 between the array surface normal of the synthetic aperture sonar array 110 and the horizontal plane satisfies 28°≤α3≤32°.

[0042] In this embodiment, the angle α3 between the normal of the synthetic aperture sonar array 110 and the horizontal plane can be 28°, 29°, 30°, 31°, 32°, or any value between two adjacent values ​​mentioned above. By controlling the angle between the normal of the synthetic aperture sonar array 110 and the horizontal plane to 28°–32°, the beam is directed towards the seabed at the optimal angle, balancing detection coverage and imaging resolution, thus improving the overall detection effect.

[0043] In some embodiments, such as Figure 2 As shown, the sonar electronics box 120 includes an air-cooled chassis, with an air inlet 121 on the lower surface of the air-cooled chassis and an air outlet 122 on the upper surface of the air-cooled chassis.

[0044] In this embodiment, the sonar electronics box 120 is an air-cooled chassis with a rectangular structure and main dimensions of 416mm × 283.2mm × 151mm. It has an air inlet 121 on the lower surface and an air outlet 122 on the upper surface, and there should be no obstructions within at least 5cm of the air inlet and outlet. The sonar electronics box 120 weighs 11kg. The sonar electronics box 120 adopts a bottom-inlet, top-outlet air-cooled structure, utilizing natural convection to enhance heat dissipation, improve the operational stability and lifespan of electronic components, and adapt to long-term continuous operation.

[0045] Secondly, such as Figure 1 and Figure 2 As shown, this application also provides an unmanned surface vessel 10, which includes the synthetic aperture side-scan sonar device 100 described above.

[0046] In this embodiment, with the continuous deepening of marine resource development and marine scientific research, unmanned surface vessels (USVs), as flexible and efficient marine exploration platforms, have received increasingly widespread attention. USVs include, but are not limited to, high-speed USVs, planing boats, and reconnaissance vessels. They typically carry underwater synthetic aperture side-scan sonar devices 100, involving sensor selection, signal processing algorithms, data transmission and storage, system stability and reliability, etc., and can complete tasks such as high-resolution imaging and precise measurement of underwater targets. This application embeds two synthetic aperture sonar arrays 110 into the receiving slots 210 on both sides of the USV 10 hull, forming a conformal integrated design. This design does not affect the vessel's speed and navigation safety, while ensuring the sonar is firmly mounted on the hull plating and that its performance is not affected.

[0047] When the synthetic aperture sonar array 110 is in operation, it requires the unmanned surface vessel (USV) platform to provide sensing information such as the USV's forward velocity, position, attitude, and water depth. The accuracy requirements for each sensor are shown in Table 1.

[0048] Table 1 Sensor accuracy requirements for payload SAS imaging

[0049] The better the stability of the unmanned surface vessel (USV) during navigation, the better the payload-based SAS imaging effect. To avoid a decrease in payload-based SAS imaging effect, the attitude and speed of the USV during navigation should meet the requirements shown in Table 2.

[0050] Table 2. SAS Imaging Flight Conditions

[0051] Because different sonar devices are installed on the unmanned surface vessel (USV) platform, in order to avoid acoustic interference between the sonar devices, it is necessary to first ensure that the operating frequency bands of the sonar devices do not overlap, and secondly, to synchronize the acoustic emission times of the sonar devices.

[0052] Based on the synthetic aperture principle, the acoustic wave emission interval must be strictly fixed during payload SAS operation. The payload SAS equipment has a reserved transmission synchronization interface. In internal synchronization mode, the payload SAS outputs a high-level signal to the transmission synchronization interface simultaneously with its acoustic wave emission. This pulse signal from the payload SAS transmission synchronization interface can be used as a synchronization source for other sonar transmissions, ensuring that all sonars emit acoustic waves simultaneously. A schematic diagram of the sonar transmission synchronization signal link connection is shown below. Figure 9 As shown.

[0053] To better understand this invention, the following is combined with... Figures 1 to 9 The technical solution of the present invention will be described in detail below: 1. Installation technical requirements are determined.

[0054] The synthetic aperture sonar array 110 is a high-resolution underwater imaging technique that utilizes the movement of a small-aperture array to effectively form a large-aperture array. By coherently processing the received echo signals, it can achieve higher resolution and a longer detection range than traditional sonar.

[0055] The synthetic aperture sonar array 110 is symmetrically and horizontally installed on both sides of the unmanned surface vessel. The size of the synthetic aperture sonar array 110 on one side can be determined according to actual needs. For example, the main body size of the synthetic aperture sonar array 110 is ≤1580mm×80mm×50mm, that is, length×width×height.

[0056] After the synthetic aperture sonar array 110 is installed on the hull, the installation attitude requirements are as follows: (1) The central axis of the array is kept horizontal, with an angle of ≤±2° with the horizontal plane.

[0057] (2) The angle between the central axis of the array and the vertical symmetry plane of the bow is ≤ ±2°.

[0058] (3) The angle between the normal of the array surface and the horizontal plane is maintained at 30°±2°.

[0059] The synthetic aperture sonar array 110 operates at speeds ranging from 3 knots to 6 knots. During operation, the surface of the synthetic aperture sonar array 110 should not be obstructed in any way (including structural obstructions or bubble turbulence).

[0060] It should be noted that, in order to avoid cavitation of the transmitting array 111 of the synthetic aperture sonar array 110 and to reduce acoustic interference on the water surface, the water depth of the transmitting array 111 and the receiving array should be kept at no less than 0.5m when they are in operation.

[0061] 2. Hull form requirements.

[0062] (1) A parallel mid-body area is set in the bilge of the ship, with a length not less than 95% of the length of the array. The mounting surface is parallel to the center line of the ship, so as to ensure that the array is flat and fits well and has an accurate posture.

[0063] (2) The synthetic aperture sonar array 110 is fixed to the mounting surface by fasteners. The array cable passes through the cabin and connects to the sonar electronic box 120 inside the boat. A sealing structure is set between the synthetic aperture sonar array 110 and the mounting surface to achieve watertight fit and prevent water from seeping into the boat.

[0064] (3) The installation device is conformally integrated with the hull and transitions smoothly without damaging the hull line or affecting the main performance indicators such as speed.

[0065] 3. Evaluation of the installation location of the synthetic aperture sonar array mounting slot.

[0066] The calculation of the skid point and skid position for U / V-shaped angled high-speed boats is based on the balance between hydrodynamic lift and gravity, combined with hull line parameters (lift angle, keel width, etc.) and empirical coefficients, to determine the submerged length during the skid stage (i.e., the distance from the skid point to the stern). The skid point refers to the critical position where the hull transitions from a displaced state to a skid state, and is usually expressed as the "distance from the skid point to the stern." This length is the longitudinal length of the hull that remains in contact with the water during the skid stage.

[0067] For example, the ship has a length L = 7.15m, a beam B = 2.85m, a gross weight W = 6.2t, a speed v = 30 knots ≈ 15.43m / s, a bottom stern angle β = 27°, a keel width b = 0.58m, a center of gravity distance from stern lg = 2.09m, and a seawater density ρ = 1025kg / m³. 3 The acceleration due to gravity is g = 9.81 m / s². 2 .

[0068] The calculation principle and empirical coefficients show that during initial slippage, the hydrodynamic lift FL begins to significantly bear the weight, and the equilibrium equation is: G≈FL (ignoring the secondary effect of buoyancy, lift dominates during the slippage stage). The hydrodynamic lift formula is: FL=0.5ρv²SLCL, where: SL is the lift area (submerged length Ls × average cross-sectional width Baavg); CL is the lift coefficient, for U / V-shaped angled boats, CL=k sin(2β) (k=0.85, based on the "High-Speed ​​Boat Design Manual").

[0069] Step 1: Calculate the average cross-sectional width Bavg.

[0070] The cross-sectional width of a U / V-shaped angled hull at draft d is determined by the keel width and the heave angle: Bavg = b + 2dtanβ; (d is taken as the design draft of 0.6m, tan27) ≈0.5095) Bavg=0.58+2×0.6×0.5095≈1.19m.

[0071] Step 2: Calculate the lift coefficient CL. CL=k sin(2β)=0.85×sin(54°)≈0.85×0.8090≈0.688; (k=0.85).

[0072] Step 3: Calculate the immersion length Ls at the starting point of the slippage.

[0073] The lift balances the gravity: 60822 = 0.5 × 1025 × (15.43)2 × Ls × 1.19 × 0.688; Simplifying, we get: Ls≈0.5×1025×238.1×1.19×0.68860822≈2.75m.

[0074] Step 4: Determine the starting position.

[0075] The distance from the starting point to the tail is the immersion length Ls; Distance from bow: L Ls=7.15 2.75 = 4.40m.

[0076] 4. Structural design.

[0077] (1) The structural dimensions of the installation device are matched with the hull components; for example, the synthetic aperture sonar array assembly includes 2 transmitting arrays and 4 receiving arrays, and each side of the unmanned surface vessel is equipped with 1 transmitting array and 2 receiving arrays. Both the transmitting and receiving arrays adopt a modular design, with the 2 transmitting arrays having the same structural design and the 4 receiving arrays having the same structural design. The main dimensions of a single transmitting array are: length 230mm × width 74mm × height 40mm, and the weight of a single transmitting array is 3.0kg. The external dimensions of the transmitting array are as follows: Figure 4 and Figure 5 As shown. The main dimensions of a single receiver array are: 640mm (length) × 74mm (width) × 40mm (height), and the weight of a single receiver array is 7.5kg. The external dimensions of the receiver array are as follows. Figure 6 and Figure 7 As shown.

[0078] (2) The dimensions of the mounting surface meet the requirements for array installation.

[0079] (3) The front profile meets the hydrodynamic design requirements and has low resistance at low speeds.

[0080] (4) The overall structure meets the watertight requirements.

[0081] 5. CFD resistance assessment.

[0082] Speed ​​refers to the maximum speed a ship can travel at its design draft in still water, and it is a crucial performance indicator in ship design. In conventional ship design, to ensure the speed target is met, an optimized hull form is fabricated into a model, and model tests are conducted in a towing tank. This vessel employs the relatively mature CFD method, utilizing STAR-CCM+ software to construct a digital tank for speed evaluation, ensuring that the design of the synthetic aperture sonar device meets both the array's own requirements and the overall hull performance specifications.

[0083] Computational domain and mesh generation: In accordance with the ITTC Ship CFD Modeling Guidelines, the inflow surface, outflow surface, side boundaries, top boundary, and bottom boundary are set at 2 times the ship's length, 4 times the ship's length, 2.5 times the ship's length, 1.5 times the ship's length, and 2.5 times the ship's length, respectively.

[0084] Boundary conditions: such as Figure 10 and Figure 11 As shown, in order to more realistically simulate the motion of unmanned vessels in water, the top, bottom, and side boundaries of the computational domain are all set as velocity inlet conditions.

[0085] Grid division: such as Figure 12As shown, structured mesh technology is the preferred technique for computational fluid dynamics due to its high accuracy, simple logical relationships, and high efficiency in flow field calculation. However, generating structured meshes for flow fields with complex shapes is a time-consuming task requiring extensive experience. Overlapping mesh technology divides the computational domain into several simple subdomains and meshes each subdomain separately, thereby greatly reducing the difficulty of generating structured meshes while ensuring mesh generation quality and improving mesh generation efficiency.

[0086] The computational domain was meshed using an automatic volumetric mesh generation method, and the mesh generation result is as follows: Figure 13 As shown.

[0087] Numerical calculations: The drag at speeds of 2kN, 4kN, 6kN, 8kN, 10kN, 12kN, 14kN, 16kN, 18kN, 20kN, 22kN, 24kN, 26kN, 28kN, 30kN, and 32kN was evaluated. The results were compared and analyzed before and after the conformal design of the synthetic aperture sonar array, as shown in Table 3.

[0088] Table 3. Comparison of drag before and after adding a synthetic aperture sonar array to the hull.

[0089] When using STAR-CCM+ for numerical simulation, the VOF (Volume Fluid Function) method is employed for free surface capture. As a typical method for free surface tracking, the VOF method boasts high computational efficiency and accuracy, and is widely used in the industry.

[0090] Based on the above derivation and analysis, the 4.4-meter section at the stern of the hull is suitable for the installation of an array device. Within the sonar operating speed range of 4–6 knots, resistance has a limited impact on the hull speed; even at high speeds, the impact of resistance on speed is relatively small. Actual ship trials have verified that the design specifications are met.

[0091] 6. Manufacturing and installation process.

[0092] Parts fabrication → Digital nesting → CNC blanking → Component assembly → On-site structure installation → Array trial installation → Welding → Array wiring installation → Cable conduit sealing → Tightness test → Cable conduit sealing.

[0093] 7. Onboard ship testing.

[0094] Actual ship tests show that the device in this application is installed in an accurate and watertight manner, and the ship's navigation performance and sonar imaging effect both meet the design specifications.

[0095] In this embodiment, the synthetic aperture side-scan sonar device provided by this application solves the problems of traditional external mounting brackets exceeding installation width limits, non-compliance with maritime regulations, significant navigation safety hazards, and cumbersome disassembly and assembly. This application employs a conformal fusion design to embed the sonar array into the hull's receiving slot, without protruding from the hull or disrupting the hull's lines, eliminating the need for repeated disassembly and assembly. This ensures stable sonar installation while balancing the unmanned surface vessel's (USV) speed and navigation safety. The array's installation attitude is precise, resulting in high image fidelity; the installation area is located in front of the hull's skidding point, without increasing drag, immersion in water, or affecting navigation speed; the structure and penetration parts are watertight and reliable, allowing for long-term underwater operation. This solution has been verified on a real vessel, demonstrating strong practicality and its applicability to other underwater detection equipment, expanding the application scenarios of USVs and reducing testing and usage costs.

[0096] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A synthetic aperture side scan sonar device designed to be conformal with an unmanned surface vehicle, for an unmanned surface vehicle having a hull with a containment slot, characterized in that, include: A synthetic aperture sonar array assembly includes two synthetic aperture sonar arrays, which are located on both sides of the unmanned surface vessel (USV) and embedded in receiving slots in the hull. The receiving slots have mounting surfaces for mounting the synthetic aperture sonar arrays, and the mounting surfaces are parallel to the central axis of the USV. The sonar electronics box is located inside the cabin of the unmanned surface vessel and is connected to the signals of the two sets of synthetic aperture sonar arrays.

2. The synthetic aperture side scan sonar apparatus of claim 1, wherein, The synthetic aperture sonar array includes a transmitting array and a receiving array. The transmitting array is located at the front end of the receiving array, which is the end of the receiving array close to the bow of the unmanned surface vessel.

3. The synthetic aperture side scan sonar apparatus of claim 2, wherein, The receiving array includes a front receiving array and a rear receiving array. The front receiving array is located between the transmitting array and the rear receiving array. The transmitting array, the front receiving array, and the rear receiving array are connected end to end in sequence.

4. The synthetic aperture side scan sonar apparatus of claim 1, wherein, The unmanned surface vessel has a parallel midbody on its hull bilge, the length of which is not less than 95% of the length of the synthetic aperture sonar array, and the parallel midbody has a receiving slot for embedding the synthetic aperture sonar array.

5. The synthetic aperture side scan sonar apparatus of claim 4, wherein, The synthetic aperture sonar array is fixedly mounted on the mounting surface of the receiving slot by fasteners. The synthetic aperture sonar array is connected to the sonar electronics box by cables. A sealing structure is provided between the mounting surface and the synthetic aperture sonar array.

6. The synthetic aperture side scan sonar apparatus of claim 4, wherein, The angle α1 between the central axis of the synthetic aperture sonar array and the horizontal plane satisfies -2°≤α1≤2°.

7. The synthetic aperture side scan sonar apparatus of claim 4, wherein, The angle α2 between the central axis of the synthetic aperture sonar array and the vertical plane passing through the bow satisfies -2°≤α2≤2°.

8. The synthetic aperture side scan sonar apparatus of claim 4, wherein, The angle α3 between the array surface normal of the synthetic aperture sonar array and the horizontal plane satisfies 28°≤α3≤32°.

9. The synthetic aperture side scan sonar apparatus of claim 1, wherein, The sonar electronics box includes an air-cooled chassis, with an air inlet on the lower surface and an air outlet on the upper surface.

10. An unmanned surface vessel, characterized in that, Includes the synthetic aperture side-scan sonar device as described in any one of claims 1-9.

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