A dynamic beam control method for forward-looking sonar of underwater vehicle

Abstract

The present invention provides a dynamic beam control method for a forward-looking sonar of an underwater vehicle, belonging to the technical field of underwater active detection. The present invention aims to solve the problems that the existing beam control method controls the beam by adjusting the signal amplitude at different positions for a specific array element spacing, is limited to the beam width and sidelobe suppression and cannot adjust the emission angle in real time, and the beam emission width is constrained by the acoustic array and is difficult to adjust for airworthiness after being determined. Based on the design concept of phased beam forming, the present invention divides the forward-looking sonar emission acoustic array into a plurality of sub-matrices, utilizes the heading and route information of the forward-looking sonar installation platform, performs phase control on the amplitude and azimuth of the emission beam, and can make the main lobe of the beam always point to the true heading of the platform, effectively improve the detection capability and early warning capability of the forward-looking sonar, effectively illuminate the heading side blind area, timely observe the route situation, ensure navigation safety, and expand the overall detection range.

Description

Technical Field

[0001] The present invention relates to the field of underwater active detection technology, and in particular to a dynamic beam control method for a forward-looking sonar of an underwater vehicle. Background Art

[0002] When underwater vehicles are navigating, they need to face dangerous and complex marine environments. In addition to the influence of waves and currents in the water, the navigation safety of the vehicle is also affected by obstacles such as seabed reefs and floating objects in the water, which seriously threaten the safety of underwater navigation. At present, there have been many publicly reported navigation safety accidents. In order to ensure the detection of obstacles in front of the platform, people have proposed an active sonar system solution, named forward-looking sonar. Forward-looking sonar usually uses a beam that emits a certain angle in the horizontal and vertical dimensions forward. The angle of the beam is determined by the mechanical structure of the sonar. The active transmission beam angle is affected by the ocean environment on the platform, which reduces the effective sound source level of the transmitted beam in the vertical and horizontal directions.

[0003] For example, the patent with announcement number CN110471334A discloses a phased array beam control device, a firmware upgrade method and a radar, including a first FPGA module for real-time processing of beam phase data; a second FPGA module for outputting corresponding instructions to multiple RF transceiver components according to the data processed by the first FPGA module; a clock and synchronization signal module for generating a clock signal and synchronizing it to the first FPGA module and the second FPGA module; a first DDR module for storing process data generated by the first FPGA module; a FLASH module for storing configuration information required for loading; a power supply module for powering the first FPGA module and the second FPGA module, and a single phased array beam control device composed of the first FPGA module and the second FPGA module. However, the existing beam transmission width is constrained by the acoustic array, and it is difficult to adjust the airworthiness after determination; mechanical scanning segmented transmission beams are mostly used, and it is difficult to achieve full digital control; the beam control method adjusts the beam by adjusting the signal amplitude at different positions for a specific array element spacing, which is mainly limited to beam width and sidelobe suppression, and the transmission angle cannot be adjusted in real time.

[0004] Therefore, a dynamic beam control method for forward-looking sonar of underwater vehicle is proposed. Summary of the invention

[0005] The purpose of the present invention is to provide a dynamic beam control method for a forward-looking sonar of an underwater vehicle, aiming to solve the problem in the above-mentioned background technology that the existing beam control method controls the beam by adjusting the signal amplitude at different positions for a specific array element spacing, is limited to the beam width and sidelobe suppression and cannot adjust the transmission angle in real time, and the beam transmission width is constrained by the acoustic array and is difficult to adjust for airworthiness after determination.

[0006] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: A dynamic beam control method for a forward-looking sonar of an underwater vehicle, comprising the following implementation steps: S1, acoustic array design and sub-array division: according to the working frequency set by the forward-looking sonar, according to the array element interval preset by the acoustic array, the array elements are arranged in a plane with a predetermined length and width, and a number of transmitting arrays are divided, and the basic structure of the acoustic array is constructed to lay the foundation for subsequent beam control; S2, transmitting sub-array beam control: the transmitting beam of the transmitting sub-array is subjected to amplitude weighting processing, and the steering angle is calculated according to the steering angle. The acoustic array of the forward-looking sonar transmits pulses in each channel with a phase delay to control the switching of the forward-looking sonar beam angle; S3, adjust the beam according to the navigation status: track the navigation status of the underwater vehicle, and when the underwater vehicle changes its course, rises or dives, immediately adjust the direction of the transmitting sub-array beam in real time; S4, beam splicing and receiving processing: centrally integrate the numerous beams of the transmitting sub-array for beam splicing processing. In the information receiving link, let all array elements participate together to collect and capture effective information, and assist in obtaining target information to achieve detection and positioning.

[0007] Furthermore, in S2, the specific implementation steps of performing amplitude weighting processing on the transmit beam of the transmit subarray are as follows:

[0008] S201: Determine the detection target and focusing effect, and select the amplitude weighting coefficient range according to the working frequency of the forward-looking sonar; S202: For each transmitting subarray, weight the transmitting beam according to the preset coefficient; S203: Establish a beam propagation model, substitute the weighted beam parameters, and simulate the propagation path and energy distribution; S204: According to the simulation results and steering angle of the beam propagation model, use the trigonometric function algorithm to calculate the phase delay of the transmitting pulse of each channel of the forward-looking sonar array; S205: Perform beam steering on each channel of the forward-looking sonar array, and control the pitch or deflection beam of the transmitting subarray to achieve the focusing function.

[0009] Furthermore, in S202, the calculation formula for the transmit beam weighting process is as follows: Let the number of transmit subarrays be N, and the initial beam amplitude of the i-th transmit subarray be , the selected weighting coefficient is , the steering angle is , the weighted beam amplitude The calculation formula is: ,in The initial phase offset related to the steering angle is Obtained by the following conversion: .

[0010] Furthermore, in S203, the calculation formula of the beam propagation model is as follows: Let the initial energy of the beam be , the propagation distance is , the dielectric attenuation coefficient is , the beam frequency is , time is , the wave speed is , the energy distribution formula of the beam propagation model is: ,in, The part represents the attenuation effect of the medium on the beam energy, which increases with the propagation distance. As increases, the energy decays exponentially; The part represents the wave characteristics of the beam during propagation, reflecting the phase change of the beam with time and distance.

[0011] Furthermore, after simulating the beam propagation path and energy distribution, the beam propagation model calculates the phase delay of the transmitted pulse of each channel. , Indicates the channel number, using trigonometric functions combined with beam propagation speed and array element spacing , the formula is as follows: ,in For the The angle between the channels and the reference direction, To take into account the additional phase angle after the steering angle correction, .

[0012] Furthermore, in S1, array elements are arranged horizontally and vertically at equal intervals on the acoustic array, each array element in the horizontal direction is led out individually, and two adjacent array elements in the vertical direction are connected in parallel and led out as a single virtual array element.

[0013] Furthermore, in S1, the beam pointing of a single sub-array of the acoustic array is controlled within the vertical ±30° and horizontal ±45° observation ranges by transmitting phase, and the transmitting power is independently controlled.

[0014] Furthermore, in S3, when the underwater vehicle surfaces, in order to avoid collision with obstacles, the point of interest of the underwater vehicle is the area above the vehicle. Due to the deviation of the area below, beam steering control is used to irradiate all the transmitting sub-array angles to the area above the vehicle.

[0015] Furthermore, in the above S4, the steps of stitching the transmitting subarray beams are as follows: S401, determine the stitching target angle range: clarify the target range that needs to cover 90° in the horizontal direction and 60° in the vertical direction, and formulate subsequent operations based on this; S402, obtain the beam parameters of each subarray: extract the parameters of each transmitting subarray including beam amplitude, phase, and frequency information as the basic data for subsequent processing; S403, calculate the beam stitching offset: calculate the offset based on the target angle range and the beam parameters of each subarray using the trigonometric function method Calculate the angle offset required for splicing the beams of each subarray; S404, adjust the angle of the transmitting subarray: adjust the transmitting angle of each transmitting subarray by controlling the channels of the sonar acoustic array according to the calculated offset; S405, perform beam splicing operation: splice the beams of each transmitting subarray according to the adjusted angle, and ensure the target coverage range in the horizontal and vertical directions by beam overlap; S406, verification and fine-tuning: test the spliced ​​beam to verify whether the expected coverage range is achieved. If not, perform fine-tuning until the requirements are met.

[0016] Furthermore, in S403, the beam splicing offset is calculated as follows: Let the horizontal target coverage angle be , the vertical target coverage angle is , No. The horizontal beamwidth of the transmitting subarray is , the vertical beam width is The total number of subarrays is , then the horizontal beam stitching offset ; Beam stitching offset in vertical direction .

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: a dynamic beam control method for a forward-looking sonar of an underwater vehicle proposed in the present invention can make the main lobe of the beam always point to the true heading of the platform, thereby significantly improving the detection capability and early warning capability of the forward-looking sonar, effectively illuminating the side blind area of ​​the heading, timely observing the route conditions, ensuring navigation safety, and expanding the overall detection range. Beam focusing is achieved through amplitude weighting, and beam performance is optimized. Phase shift transmission control can accurately adjust the beam angle. A full digital beam control method and a full-transmit and full-receive array design are adopted to obtain a greater spatial gain under the condition of limited acoustic array size. Phased transmission of more than 1,000 channels is achieved for the first time, providing a hardware foundation for beam optimization control, realizing an integrated and lightweight design, and enhancing the system integration and adaptability; the beam pointing and opening angle can also be adjusted according to the platform's navigation posture and the obstacle avoidance target situation, reducing reverberation interference, improving the echo image signal-to-noise ratio, creating good conditions for autonomous detection and classification of targets, and improving the overall detection performance. In the collision avoidance sonar of unmanned underwater vehicles, the problems of target identification and autonomous collision avoidance can be solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the overall process of the present invention; Figure 2 A schematic diagram of the beam direction change processing logic of the present invention; Figure 3 It is a schematic diagram of the acoustic array array of the present invention; Figure 4 It is a schematic diagram of the transmit beam sideslip compensation of the present invention; Figure 5 It is a schematic diagram of focusing the transmission beam of the present invention; Figure 6 It is a schematic diagram of the transmitting beam following steering of the present invention; Figure 7 It is a polar coordinate schematic diagram of the transmit beam amplitude-angle distribution of the present invention; Figure 8 It is a schematic diagram of the radiation direction of the transmission beam of the present invention; Fig. 9 It is a schematic diagram of the transmission beam splicing of the present invention; Fig.10 It is a schematic diagram of the overall structure of the acoustic array of the present invention; Fig.11 It is a schematic diagram of the acoustic array assembly structure of the present invention.

[0019] In the figure: 1. substrate; 11. sealing groove; 12. protrusion; 13. first O-ring; 2. acoustic array flat panel; 3. multi-channel transmitting and receiving module; 4. energy storage capacitor; 5. pressure-bearing watertight shell; 6. pressure-bearing watertight cover plate; 61. reinforced grille; 62. second O-ring; 7. power module; 8. integrated processing and control module; 9. watertight connector. DETAILED DESCRIPTION

[0020] 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.

[0021] In order to solve the problem that the existing beam control method controls the beam by adjusting the signal amplitude at different positions for a specific array element spacing, is limited to the beam width and sidelobe suppression and cannot adjust the transmission angle in real time, and the beam transmission width is constrained by the acoustic array and is difficult to adjust after it is determined, please refer to Figure 1-Figure 9 , provide the following preferred technical solutions:

[0022] A dynamic beam control method for a forward-looking sonar of an underwater vehicle includes the following specific implementation steps:

[0023] Step 1: Acoustic array design and sub-array division. According to the acoustic array design operating frequency f, in a plane with a length of d and a width of I (d, I>15000 / f), n array elements are arranged in the length direction according to the array element interval of 3000 / f, where n=[df / 3000], and m array elements are arranged in the width direction, where m=[If / 3000]. Then the acoustic array is divided into p*q transmitting arrays at an interval of [4500 / f]*[7500 / f]. Each transmitting array can transmit a separate beam. After the beams of these transmitting arrays are spliced, a detection range of H: 16.6p° is formed in the horizontal range and V: 10q° is formed in the vertical range. In this way, the basic architecture of the acoustic array is constructed, laying the foundation for subsequent beam control.

[0024] Step 2: Transmitting subarray beam control, amplitude weighting of the transmitting beam of each transmitting subarray to achieve the focusing function of the total detection beam. When the verticality of the transmitting subarray decreases, the horizontal beam directivity index increases under the same transmitting energy. The phase delay of the transmitting pulse of each channel of the forward-looking sonar acoustic array is calculated according to the steering angle. By performing beam steering on each channel of the sonar acoustic array, the transmitting subarray phased transmission pitch or deflection beam is controlled to achieve flexible changes in the beam angle of the forward-looking sonar system to meet different exploration needs;

[0025] In step 2, the specific implementation steps of amplitude weighted processing of the transmitting beam of the transmitting subarray are as follows: S201: determine the detection target and focusing effect, and select the amplitude weighted coefficient range according to the working frequency of the forward-looking sonar; S202: for each transmitting subarray, weight the transmitting beam according to the preset coefficient; S203: establish a beam propagation model, substitute the weighted beam parameters, and simulate the propagation path and energy distribution; S204: according to the simulation results and steering angle of the beam propagation model, use the trigonometric function algorithm to calculate the phase delay of the transmitting pulse of each channel of the base array of the forward-looking sonar sound; S205: perform beam steering on each channel of the forward-looking sonar sound base array, and control the pitch or deflection beam of the transmitting subarray to achieve the focusing function.

[0026] In S202, the calculation formula for the transmit beam weighting process is as follows: Let the number of transmit subarrays be , No. The initial beam amplitude of the transmitting subarray is , the selected weighting coefficient is , the steering angle is , the weighted beam amplitude The calculation formula is: ,in is the initial phase offset related to the steering angle, according to the steering angle Obtained by the following conversion: .

[0027] In S203, the calculation formula of the beam propagation model is as follows: Let the initial energy of the beam be , the propagation distance is , the dielectric attenuation coefficient is , the beam frequency is , time is , the wave speed is , the energy distribution formula of the beam propagation model is: ,in, The part represents the attenuation effect of the medium on the beam energy, which increases with the propagation distance. As increases, the energy decays exponentially; The part represents the wave characteristics of the beam during propagation, reflecting the phase change of the beam with time and distance.

[0028] After the beam propagation model simulates the beam propagation path and energy distribution, it calculates the phase delay of the transmitted pulse of each channel. hour, Indicates the channel number, using trigonometric functions combined with beam propagation speed and array element spacing , the formula is as follows: ,in For the The angle between the channels and the reference direction, To take into account the additional phase angle after the steering angle correction, .

[0029] Step 3: Adjust the beam according to the navigation status. When the underwater vehicle changes its heading, the beams of each transmitting sub-array are adjusted in real time to ensure that the beam points to the navigation direction, achieving accurate detection and wider angle detection range coverage. When the underwater vehicle floats up, the transmitting sub-array angle irradiates the area above the vehicle, and adjusts the angle downward accordingly when diving to ensure navigation safety.

[0030] Step 4: Beam stitching and receiving processing. Splice the transmitting sub-array beams and adjust the transmitting angle. Through beam stitching and overlapping, it can cover 90° in the horizontal direction and 60° in the vertical direction. During reception, all array elements participate in beam forming. The beam width is 2.23° in both vertical and horizontal directions. Beam forming is performed at intervals of 1.5°. 40 beams are formed in the vertical direction and 60 beams are formed in the horizontal direction, totaling 2400 receiving beams to obtain target information and realize detection and positioning functions.

[0031] Specifically, array elements are arranged in a plane according to the design operating frequency and relevant dimensions of the acoustic array and divided into transmitting arrays. Each transmitting array transmits a separate beam that is spliced ​​into a specific detection range. At the same time, the transmitting sub-array beam amplitude can be weighted to achieve focusing. The phase delay can be calculated according to the steering angle to control the pitch or deflection of the transmitting sub-array beam, thereby achieving beam angle change, and the transmitting beam can be adaptively controlled according to the heading, route, attitude, deflection rate and speed of the underwater vehicle. For example, the sub-array beam is adjusted when the heading changes, and the irradiation area is changed accordingly when surfacing or diving. When diving, the beam pointing can be accurately controlled in response to different states, suspected obstacles can be focused, and the detection capability of the turning area can be improved. The effect is significant, and the main lobe of the beam can always point to the true heading of the platform, thereby improving the detection and early warning capabilities, expanding the detection range, optimizing the beam performance, improving the system integration and adaptability, and improving the echo image quality. It has important application value in the sonar systems of various underwater vehicles and can effectively solve the problems of difficult target identification and weak autonomous collision avoidance capabilities.

[0032] like Figure 1 and Figure 10-11As shown, this embodiment shows the specific structure of the acoustic array of the forward-looking sonar transmission beam control method, including the following technical solutions: a device for the dynamic beam control method of the forward-looking sonar of an underwater vehicle, including a substrate 1 and an acoustic array plate 2 fixedly arranged on the outer wall of one side of the substrate 1, a sealing groove 11 is opened on the outer wall of the substrate 1 away from the acoustic array plate 2, a protrusion 12 is fixedly arranged on the bottom plate at the middle of the sealing groove 11, a multi-channel transmitting and receiving module 3 is fixedly connected to the outer wall at the middle of the protrusion 12, an energy storage capacitor 4 is fixedly connected to the outer wall of one side of the multi-channel transmitting and receiving module 3, and the sealing groove 11 is provided with a sealing groove 11. A pressure-bearing watertight shell 5 is fixedly connected inside, and the pressure-bearing watertight shell 5 is sleeved on the side wall of the protrusion 12, and a pressure-bearing watertight cover plate 6 is fixedly connected to the outer wall of the end port of the pressure-bearing watertight shell 5. The pressure-bearing watertight cover plate 6 is a convex structure, and an isolation ring that is movably engaged between the inner walls of the end port of the pressure-bearing watertight shell 5 is arranged on one side of the outer wall. A reinforcing grid 61 is fixedly connected between the inner walls of the isolation ring, and a power module 7 and a comprehensive processing and control module 8 are fixedly connected to the outer wall of the pressure-bearing watertight cover plate 6 in the grid of the reinforcing grid 61 in sequence, and a watertight connector 9 is fixedly connected to the outer wall of the pressure-bearing watertight shell 5 away from the isolation ring. The end of the protrusion 12 extends to the outside of the port of the sealing groove 11, and a first O-type sealing ring 13 is fixedly sleeved on the side wall at the end of the protrusion 12, and the outer end of the first O-type sealing ring 13 is flush with the side wall of the protrusion 12. A second O-ring 62 is fixedly embedded on the outer wall of the isolation ring. The second O-ring 62 is provided with two rings. When the isolation ring is engaged between the inner walls of the ports of the pressure-bearing watertight shell 5, the second O-ring 62 is in contact with the inner walls of the ports of the pressure-bearing watertight shell 5 for watertightness. The acoustic array of the collision avoidance forward-looking sonar selects a working center frequency of 40kHz, and adopts a 2304-element flat array and a 1152-channel transmitting and receiving unit to realize three-dimensional active phased detection and obtain a real-time three-dimensional echo image of the target; the structure adopts an integrated and lightweight design, and the pressure-bearing watertight shell 5 (electronic compartment) and the acoustic array flat panel 2 (acoustic array) form a whole, simplifying the UUV platform installation interface, with an outline size of 900×900×600mm, of which the diameter of the electronic compartment is 770mm, realizing the modularization of the forward-looking sonar.

[0033] Taking into account the platform installation mechanical structure interface design and the convenience of hardware circuit module division, it was finally determined that 48 array elements would be evenly spaced horizontally and vertically in the collision avoidance sonar array, totaling 48×48=2304 elements. The element spacing was 17.5mm and the effective size of the array surface was 840mm×840mm.

[0034] Each array element in the horizontal direction is led out separately, and two adjacent array elements in the vertical direction are connected in parallel on the circuit as a single virtual array element. The whole array leads out 48×24=1152 channels in total, and the array elements use composite rod transducers shared by both transmitting and receiving. When transmitting, the whole array is divided into 48 sub-arrays, each of which consists of 8 vertical array elements and 6 horizontal array elements, and is independently driven by 24 power amplifiers to form a beam; the beam pointing of a single sub-array can be arbitrarily adjusted within the vertical ±30° and horizontal ±45° observation range through the transmission phase control, and the transmission power can also be independently controlled; the whole array is driven by 1152 independent power amplifiers, and the beam pointing and amplitude weighting of 48 sub-arrays can be adjusted according to the platform working mode, motion posture and obstacle target state to optimize the illumination range, highlight suspicious targets, and reduce reverberation interference. When receiving, the whole array performs two-dimensional array beamforming processing to obtain the vertical and horizontal angle information of the target, and combines echo ranging to achieve three-dimensional imaging of the target.

[0035] Among them, the multi-channel transmitting and receiving module 3 adopts a 6U standard height board design and is installed in two chassis on the back of the substrate 1, minimizing the connection length between the front-end acoustic array flat panel 2 circuit and the multi-channel transmitting and receiving module 3, reducing noise interference; the power supply module 7 and the integrated processing and control module 8 have large power consumption and are close to the pressure-bearing watertight cover plate 6 for heat dissipation; two O-rings are used between the pressure-bearing watertight shell 5 and the substrate 1 and the pressure-bearing watertight cover plate 6 to achieve watertightness.

[0036] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0037] Although 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 the embodiments without departing from the principles and spirit of the invention, and the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A dynamic beam control method for a forward-looking sonar of an underwater vehicle, characterized in that: The implementation steps include: S1. Acoustic array design and sub-array division: according to the working frequency set by the forward-looking sonar, according to the array element interval preset by the acoustic array, the array elements are arranged in a plane with a predetermined length and width, and several transmitting arrays are divided to construct the basic structure of the acoustic array to lay the foundation for subsequent beam control; S2. Transmitting sub-array beam control: amplitude-weighted processing is performed on the transmitting beam of the transmitting sub-array, and the phase delay of the transmitting pulse of each channel of the acoustic array of the forward-looking sonar is calculated according to the steering angle, and the forward-looking sonar beam angle is controlled to switch; S3. Beam adjustment according to navigation status: tracking the navigation status of the underwater vehicle, when the underwater vehicle changes its course, floats up or dives, the pointing direction of the transmitting sub-array beam is adjusted immediately and in real time; S4. Beam splicing and receiving processing: the numerous beams of the transmitting sub-array are centrally integrated for beam splicing processing, and in the information receiving link, all array elements are allowed to participate together to collect and capture effective information. , assist in obtaining target information to achieve detection and positioning; in the said S2, the specific implementation steps of amplitude weighted processing of the transmitting beam of the transmitting subarray are as follows: S201: determine the detection target and focusing effect, and select the amplitude weighted coefficient range according to the working frequency of the forward-looking sonar; S202: for each transmitting subarray, weight the transmitting beam according to the preset coefficient; S203: establish a beam propagation model, substitute the weighted beam parameters, and simulate the propagation path and energy distribution; S204: according to the simulation results and steering angle of the beam propagation model, use the trigonometric function algorithm to calculate the phase delay of the transmitting pulse of each channel of the array of the forward-looking sonar sound; S205: perform beam driving on each channel of the forward-looking sonar sound array, and control the pitch or deflection beam of the transmitting subarray to achieve the focusing function; in the said S202, the calculation formula of the transmitting beam weighted processing is as follows: let the number of transmitting subarrays be N, and the initial beam amplitude of the i-th transmitting subarray be , the selected weighting coefficient is , the steering angle is , the weighted beam amplitude The calculation formula is: ,in is the initial phase offset related to the steering angle, according to the steering angle Obtained by the following conversion: In S203, the calculation formula of the beam propagation model is as follows: Let the initial energy of the beam be , the propagation distance is , the dielectric attenuation coefficient is , the beam frequency is , time is , the wave speed is , the energy distribution formula of the beam propagation model is: ,in, The part represents the attenuation effect of the medium on the beam energy, which increases with the propagation distance. As increases, the energy decays exponentially; The part represents the wave characteristics of the beam during propagation, reflecting the phase change of the beam with time and distance.

2. The method for dynamic beam control of a forward-looking sonar of an underwater vehicle according to claim 1, characterized in that: The beam propagation model simulates the beam propagation path and energy distribution, and then calculates the phase delay of the transmitted pulse of each channel. , Indicates the channel number, using trigonometric functions combined with beam propagation speed and array element spacing , the formula is as follows: ,in For the The angle between the channels and the reference direction, Considering the additional phase angle after steering angle correction, .

3. The method for dynamic beam control of a forward-looking sonar of an underwater vehicle according to claim 1, characterized in that: In S1, array elements are arranged horizontally and vertically at equal intervals on the acoustic array, each array element in the horizontal direction is led out separately, and two adjacent array elements in the vertical direction are connected in parallel as a single virtual array element.

4. The method for dynamic beam control of a forward-looking sonar of an underwater vehicle according to claim 1, characterized in that: In S1, the beam pointing of a single sub-array of the acoustic array is controlled within the vertical ±30° and horizontal ±45° observation ranges by transmitting phase, and the transmitting power is independently controlled.

5. The method for dynamic beam control of a forward-looking sonar of an underwater vehicle according to claim 1, characterized in that: In S3, when the underwater vehicle surfaces, in order to avoid collision with obstacles, the point of interest of the underwater vehicle is the area above the vehicle. Due to the deviation of the area below, beam steering control is used to irradiate the transmitting sub-array angles to the area above the vehicle.

6. The method for dynamic beam control of a forward-looking sonar of an underwater vehicle according to claim 1, characterized in that: In the above S4, the steps of splicing the transmitting subarray beams are as follows: S401, determine the splicing target angle range: clarify the target range that needs to cover 90° in the horizontal direction and 60° in the vertical direction, and formulate subsequent operations based on this; S402, obtain the beam parameters of each subarray: extract the parameters of each transmitting subarray including beam amplitude, phase, and frequency information as the basic data for subsequent processing; S403, calculate the beam splicing offset: according to the target angle range and the beam parameters of each subarray, use the trigonometric function method to calculate the offset of each subarray. The angle offset required for subarray beam splicing; S404, adjust the transmitting subarray angle: according to the calculated offset, adjust the transmitting angle of each transmitting subarray by controlling each channel of the sonar acoustic array; S405, perform beam splicing operation: according to the adjusted angle, splice the beams of each transmitting subarray, and ensure the target coverage range in the horizontal and vertical directions through beam overlap; S406, verification and fine-tuning: test the spliced ​​beam to verify whether the expected coverage range is achieved. If not, perform fine-tuning until the requirements are met.

7. The method for dynamic beam control of a forward-looking sonar of an underwater vehicle according to claim 6, characterized in that: In S403, the beam splicing offset is calculated as follows: Let the horizontal target coverage angle be , the vertical target coverage angle is , the horizontal beamwidth of the i-th transmitting subarray is , the vertical beam width is , the total number of sub-arrays is n, then the horizontal beam stitching offset is ; Beam stitching offset in vertical direction .

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