Cognitive feedback based method for luffing stabilization of a dolly sonar transmit beam

Abstract

This invention provides a method for stabilizing the pitch of a dipping sonar transmission beam based on cognitive feedback. Based on the design concepts of phased beamforming and cognitive sonar, this method uses the target detection and tracking information feedback of the sonar to stabilize the pitch of the transmission beam using phased beamforming. This method ensures that the main lobe of the beam always points to the tracked target, effectively improving the signal-to-mixing ratio and identification accuracy of the dipping sonar for that target.

Description

TECHNICAL FIELD

[0001] The present application relates to the underwater active detection technical field, specifically, it relates to a kind of based on cognitive feedback's hoist and drop type sonar launch beam pitch stabilizing method. BACKGROUND

[0002] Flexible hoist and drop type sonar has the advantages of freely selecting underwater branch machine hoist and drop depth, far away from platform self interference, good adaptability, etc., common such as ship hoist and drop type small target detection sonar, helicopter hoist and drop anti-submarine sonar, etc., but at the same time, underwater branch machine of hoist and drop type sonar is easily influenced by marine environmental factors, and posture abnormality such as underwater posture tilt, shaking and rotation is generated, which leads to the decline of sonar detection capability.

[0003] Underwater branch machine of hoist and drop type active sonar usually adopts horizontal circumference omnidirectional launch form.Assuming that the installation platform hovers in stationary state, hoist and drop underwater branch machine of sonar to still water, then the circumference omnidirectional launch beam main lobe plane of hoist and drop type sonar should be kept in horizontal plane.But in actual working environment, due to the impact of sea current, surge, etc., underwater branch machine will not be able to keep vertical state, and the omnidirectional launch beam main lobe plane of hoist and drop sonar will deviate from horizontal plane, so that the effective sound source level of launch beam in horizontal direction will be reduced.

[0004] If the launch beam in 360° circumference range can be stabilized in horizontal plane under the condition of transducer array tilt, there are currently two main methods: one method is to install a quick-response mechanical servo stabilizing device on underwater branch machine, and according to the real-time measurement information of attitude sensor, the transducer array is adjusted to horizontal plane by using the stabilizing device, and the stabilizing device is usually a large-scale hydraulic device, which is bulky, low in precision and difficult to hoist; the other method is to expand sonar hardware to support three-dimensional directivity launch or horizontal circumference rapid scanning launch, which will greatly increase the scale and complexity of sonar transmitter and transducer array, and it is currently difficult to realize on hoist and drop type sonar. SUMMARY

[0005] In view of the defects in the prior art, the purpose of the present application is to provide a kind of based on cognitive feedback's hoist and drop type sonar launch beam pitch stabilizing method, to solve the problem that the effective sound source level of the launch beam of the hoist and drop type sonar is lost due to the posture tilt, shaking, etc.of underwater branch machine, so that the launch beam cannot keep horizontal or stabilize the direction of the current tracking target.

[0006] According to the hoist and drop type sonar launch beam pitch stabilizing method based on cognitive feedback provided by the present application, the following steps are included:

[0007] Step 1: according to the attitude angle information of underwater branch machine, the transformation matrix corresponding to each attitude angle is obtained, and the vector rotation transformation relationship between underwater branch machine coordinate system and geodetic coordinate system is established;

[0008] Step 2: According to the detection trajectory of the tracking target by the sonar, the feedback azimuth of the beam tilt stability is determined as the azimuth of the tracking target, and the tilt angle of the underwater device at the feedback azimuth is calculated through the azimuth vector of the tracking target in the underwater device coordinate system;

[0009] Step 3: Taking the tilt angle of the underwater device at the feedback azimuth of the tracking target as the guide angle of the preformed phased beam of the sonar transmitting transducer array, the phase shift transmission control is performed on each layer of transmitting elements to complete the omnidirectional phased tilt transmission.

[0010] Step 4: Steps 1 to 3 are repeated in a loop, and according to the real-time updated attitude angle measurement data and the azimuth information of the tracking target, the sonar transmission state is adjusted through the tilt angle to make the phased tilt transmission beam main lobe continuously aim at the tracking target, thereby realizing multi-cycle phased beam tilt stability.

[0011] Preferably, the attitude angle information includes the roll angle, pitch angle and heading angle of the underwater device obtained based on the navigation and attitude sensor embedded in the underwater device of the dangled sonar.

[0012] Preferably, the transformation matrix corresponding to each attitude angle adopts the cosine transformation matrix corresponding to each attitude angle.

[0013] Preferably, the vector rotation transformation relationship between the underwater device coordinate system and the geodetic coordinate system is:

[0014] r2=R ΨΘΦ r1

[0015] Wherein, the conversion matrix R ΨΘΦ =ΨΘΦ, Ψ, Θ, Φ are the cosine transformation matrices corresponding to the three attitude angles, and r1, r2 are the analytical expressions of the same space vector in the underwater device coordinate system and the geodetic coordinate system, respectively.

[0016] Preferably, the calculation method of the tilt angle is:

[0017]

[0018] Wherein, β is the tilt angle of the underwater device at the feedback azimuth, r1=(x1;y1;z1), and r1 is the analytical expression of the current azimuth of the tracking target in the underwater device coordinate system;

[0019] Preferably, the transmitting elements of each layer are arranged along the direction perpendicular to the horizontal plane.

[0020] Preferably, the phase shift transmission control is to calculate the transmission pulse phase delay of each channel of the sonar transmitting transducer array according to the guide angle, and control the phased tilt transmission beam of the transmitting elements.

[0021] Preferably, the method for calculating the phase delay of the transmitted pulse is as follows:

[0022]

[0023] Where i takes values ​​from 1 to N, N is the number of channels in the sonar transmitting transducer array, d is the spacing between adjacent channels, λ is the wavelength of the sound pulse signal, and β is the tilt angle of the underwater sub-unit in the feedback orientation.

[0024] Preferably, the sonar transmitting transducer array is a circumferential omnidirectional transmitting transducer array.

[0025] Preferably, if the transmitted beam of the feedback azimuth is kept horizontal, the pitch angle of the tracked target in the direction perpendicular to the horizontal plane in the geodetic coordinate system is 0°; if the difference between the tracked target and the sonar depth is large or the sound speed gradient changes greatly, such that the transmitted beam of the feedback azimuth is on the same horizontal plane as the tracked target, then different pitch stabilization angles of the transmitted beam are set by the sonar display and control console so that the main lobe sound ray of the transmitted beam can continuously point to the tracked target.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. This invention is based on the design concepts of phased beamforming and cognitive sonar. It utilizes the target detection and tracking information feedback of sonar to perform phased beam pitch stabilization, which can improve the adaptability of dipping active sonar. Under the same conditions, it does not require the installation of attitude servo stabilization devices on the underwater sub-unit, nor does it require expanding the hardware such as the transducer array and transmitter of the underwater sub-unit from two-dimensional to three-dimensional. It can achieve phased beam pitch with a smaller underwater sub-unit equipment scale.

[0028] 2. This invention has high timeliness and accuracy, and can resist the impact of harsh marine environments on the performance of dipping sonar. It adjusts the vertical pitch angle of the sonar transmission beam in real time according to the target tracking information, so that the main lobe of the beam is always aimed at the tracked target, thereby improving the signal-to-mix ratio and identification accuracy of the target. Attached Figure Description

[0029] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0030] Figure 1 This is a schematic diagram of coordinate system rotation transformation;

[0031] Figure 2 This is a schematic diagram of beam pitch when the underwater sub-unit is tilted.

[0032] Figure 3 This is a schematic diagram of the delay control for each transmission channel;

[0033] Figure 4 This is a schematic diagram of the implementation process of the present invention;

[0034] Figure 5 It is a beam directivity curve;

[0035] Figure 6 It is a circular undulation diagram of beam gain for phased-array elevation. Detailed Implementation

[0036] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0037] This invention proposes a method for stabilizing the elevation of a dipping sonar transmission beam based on cognitive feedback, which mainly includes the following steps:

[0038] Step 1: Based on the attitude angle information of the underwater sub-unit, obtain the transformation matrix corresponding to each attitude angle, and establish the vector rotation transformation relationship between the underwater sub-unit coordinate system and the geodetic coordinate system.

[0039] Specifically, the coordinate system transformation matrix is ​​generated first:

[0040] Based on the attitude sensor embedded in the dipping sonar submersible, the roll angle θ and pitch angle of the submersible are obtained. Given a heading angle ψ, calculate the cosine transform matrix corresponding to each attitude angle:

[0041]

[0042]

[0043]

[0044] Then, based on the transformation matrix R ΨΘΦ =ΨΘΦ, establish the vector rotation transformation relationship between the underwater sub-unit coordinate system and the geodetic coordinate system:

[0045] r2=R ΨΘΦ r1 (4)

[0046] Where r1 and r2 are the analytical expressions of the same spatial vector in the underwater sub-machine coordinate system and the geodetic coordinate system, respectively.

[0047] Step 2: Based on the sonar's detection trajectory of the tracked target, determine the feedback azimuth of the beam elevation stabilization as the location of the tracked target. Calculate the tilt angle of the underwater sub-unit at the feedback azimuth using the azimuth vector of the tracked target in the underwater sub-unit's coordinate system. Specifically, if the transmitted beam at the feedback azimuth is kept horizontal, the elevation angle of the tracked target perpendicular to the horizontal plane in the geodetic coordinate system is 0°. If the depth difference between the tracked target and the sonar is large, or the sound velocity gradient changes significantly, causing the transmitted beam at the feedback azimuth to be outside the same horizontal plane as the tracked target, then different transmitted beam elevation stabilization angles are set on the sonar control console to ensure that the main lobe of the transmitted beam continuously points towards the tracked target.

[0048] The method for calculating the tilt angle is as follows:

[0049]

[0050] Where ββ is the tilt angle of the underwater sub-unit in the feedback orientation, and r1=(x1;y1;z1), r1 is the analytical expression of the current orientation of the tracking target in the coordinate system of the underwater sub-unit.

[0051] Specifically, calculate the tilt angle of the underwater sub-unit in the feedback orientation:

[0052] Once the sonar detects a target and establishes a tracking trajectory, the target's azimuth α can be used as the feedback azimuth for beam elevation stabilization. Assuming the underwater sub-unit is at a similar depth to the target, and the transmitted beam at that azimuth needs to be kept horizontal, the azimuth vector of the tracked target in the geodetic coordinate system can be represented by r2 = (sinα; cosα; 0). If the elevation angle of the transmitted beam at that azimuth is η, then the azimuth vector of the tracked target in the geodetic coordinate system can be represented by r2 = (sinα; cosα; tanη). The expression for r2 in the underwater sub-unit's coordinate system is r1 = (x1; y1; z1):

[0053]

[0054] The tilt angle β of the underwater submersible at this feedback orientation is calculated as follows:

[0055]

[0056] Step 3: Using the tilt angle of the underwater sub-unit at the target feedback azimuth as the guiding angle for the phased beam pre-forming of the sonar transmitting transducer array, phase-shift transmission control is performed on each layer of transmitting elements to complete omnidirectional phased elevation transmission. Each layer of transmitting elements is arranged perpendicular to the horizontal plane. Phase-shift transmission control calculates the phase delay of the transmission pulses of each channel of the sonar transmitting transducer array based on the guiding angle, controlling the phased elevation transmission beam of the transmitting elements. The sonar transmitting transducer array adopts a circular omnidirectional transmitting transducer array.

[0057] The method for calculating the phase delay of the transmitted pulse is as follows:

[0058]

[0059] Where i takes values ​​from 1 to N, N is the number of channels in the sonar transmitting transducer array, d is the spacing between adjacent channels, λ is the wavelength of the sound pulse signal, and β is the tilt angle of the underwater sub-unit in the feedback orientation.

[0060] Specifically, time delay generation and phased-controlled transmission: the tilt angle of the underwater sub-unit at the feedback azimuth of the tracking target is used as the guiding angle for the phased-controlled beam preformation of the sonar transmitting transducer array, and phase-shift transmission control is performed on each layer of transmitting elements arranged along the z-axis.

[0061] If the sonar transmitting transducer array is an N-channel array with adjacent spacing d, and the wavelength λ of the detected acoustic pulse signal is given, the phase delay of the transmitted pulse in each channel is as follows:

[0062]

[0063] Where i takes values ​​from 1 to N.

[0064] Step 4: Repeat steps 1 to 3 in a loop. Based on the real-time updated attitude angle measurement data and the azimuth information of the tracked target, adjust the beam pre-forming guide angle to ensure the main lobe of the phased-array pitch transmission beam continuously aims at the tracked target, achieving multi-cycle phased-array pitch stabilization. Specifically, update the transformation matrix R based on the real-time attitude measurement data from the sonar underwater sub-unit's attitude sensor. ΨΘΦ =ΨΘΦ; Based on the target azimuth information fed back by the sonar software, update the tilt angle β of the underwater sub-unit at that azimuth; calculate and update the delay φ of each transmission channel. i This allows the main lobe of the phased-array pitch-transmitted beam to continuously aim at the tracked target until the target disappears or a new master control command is received.

[0065] The following embodiments implement the cognitive feedback-based beam stabilization method for dipping-type sonar based on the present invention, using a flexible dipping-type small target detection sonar. Under normal detection conditions, once the sonar establishes a tracking trajectory for a target, the beam elevation stabilization control function can be activated. Embodiment 1 assumes that the target and the dipping sonar are at roughly the same depth, ensuring that the beam transmitted in the target's azimuth remains in the horizontal plane. Embodiment 2 assumes a significant difference in depth between the target and the sonar, or a large change in sound velocity gradient, and sets different beam elevation stabilization angles via the sonar control console, ensuring that the main lobe of the transmitted beam continuously points towards the tracked target.

[0066] Example 1

[0067] Step 1: Generate the coordinate system transformation matrix

[0068] An underwater submersible coordinate system X'Y'Z' can be defined, with the origin at the center of the submersible. The three coordinate axes x', y', and z' point east, north, and vertically upward, respectively. When the underwater submersible is vertical and its heading angle accurately points north, the underwater submersible coordinate system X'Y'Z' coincides with the geodetic coordinate system XYZ.

[0069] The attitude sensor embedded in the dipping sonar submersible acquires real-time attitude data such as roll, pitch, and heading. The upward angle on the x' axis can be defined as the roll angle θ, and the downward angle on the y' axis as the pitch angle. The clockwise rotation angle about the z' axis is the heading angle ψ. The coordinate system rotation transformation is illustrated as follows: Figure 1 As shown.

[0070] In the current cycle, if the roll angle θ = 2° and the pitch angle of the underwater sub-unit's attitude sensor is... With a heading angle ψ = 0°, calculate the coordinate system transformation matrix R according to formulas (1) to (3). ΨΘΦ =ΨΘΦ.

[0071] Substituting the z' axis of the underwater sub-unit, i.e. the attitude vector r1 = (0; 0; 1) of the underwater sonar sub-unit in its own coordinate system, into formula (4), we can obtain the real-time attitude vector r2 = (-0.0349; 0.1045; 0.9939) of the underwater sub-unit in the geodetic coordinate system. The tilt direction of the underwater sub-unit is 341.5266° and the tilt angle is 6.3234°.

[0072] Step 2: Calculate the tilt angle of the underwater submersible at the feedback azimuth.

[0073] Once the sonar detects an underwater target and establishes a tracking trajectory for that target, it acquires the target's horizontal azimuth and distance information in real time. With the y-axis pointing north as 0° and clockwise as positive, the target's azimuth α is assumed to be at a similar depth to the underwater sub-unit and the target. The azimuth vector of the target in the geodetic coordinate system during the current cycle is represented by r2 = (sinα; cosα; 0).

[0074] In the current cycle, if the azimuth of the tracked target is α = 20°, according to formula (5), the azimuth vector r1 = (0.3418; 0.9358; -0.864) of the target in the underwater sub-unit coordinate system is obtained, and the angle β = 4.9539° between the azimuth vector and the vertical plane X'OY' of the underwater sub-unit is calculated.

[0075] Step 3, Delay Generation and Phased Transmission

[0076] The tilt angle of the underwater sub-unit at the target tracking feedback azimuth, i.e., the angle β between the target's azimuth vector and the sonar sub-unit's X'OY' plane, is used as the guiding angle for the pre-formation of the phased beam of the sonar transmitter transducer array. Phase-shift transmission control is then applied to each layer of transmitting elements arranged along the z' axis, achieving omnidirectional phased beam elevation. This results in the main lobe of the transmitting beam pointing outwards from a single plane in all directions around the underwater sub-unit's circumference, instead presenting a conical shape in three-dimensional space. A schematic diagram of the beam elevation under the tilted state of the underwater sub-unit is shown below. Figure 2 As shown.

[0077] Assume the dipping sonar uses a circular omnidirectional transmitting transducer array. This array consists of N=8 channels of circular transducers in the vertical direction, with an array spacing of λ / 2 between adjacent channels. The phased elevation angle β = 4.9539° is shown in the diagram below. Figure 3 As shown in Table 1, the phase delay of each transmission channel is calculated according to formula (7):

[0078] Table 1. Pitch-to-Elevation Phase Delay Table for Each Channel

[0079] Channel number 1 2 3 4 5 6 7 8 Phase delay (radians) 0 0.2713 0.5426 0.8139 1.0852 1.3564 1.6277 1.8990

[0080] The beam directivity curves of phased-array transmission and in-phase transmission are as follows: Figure 4 As shown, in the direction of phased pitch angle β = 4.9539°, the normalized amplitude of the beam output increases from 0.8178 to 1, and the beam gain is increased by 1.7471dB.

[0081] In the horizontal omnidirectional circular azimuth, the circular fluctuation of the phased-array pitch beam gain is as follows: Figure 5 As shown, compared to the gain of the transmitted beam projected in the horizontal plane without vertical beam control, phased beam pitch stabilization compensates for the 1.75 dB gain loss caused by attitude tilt in the guidance azimuth. Within the 360° horizontal circular plane, varying degrees of beam gain compensation are achieved in a 133° sector, while the beam gain is further lost in the remaining 227° sector. Therefore, achieving phased beam stabilization in the guidance azimuth comes at the cost of temporarily reducing beam gain in other azimuths.

[0082] Step 4, Multi-period phased beam pitch stabilization

[0083] In the next pulse cycle, steps 1 to 3 are repeated cyclically. Based on the real-time updated attitude measurement data and the azimuth information of the tracked target, the transmitter state is adaptively adjusted so that the main lobe of the phased-array elevation beam continuously aims at the tracked target, improving the sonar's signal-to-mixing ratio and identification accuracy, until the tracked target disappears or a new master control command is received. The implementation process of this invention is illustrated below. Figure 6 As shown.

[0084] Example 2

[0085] Step 21, Generate coordinate system transformation matrix

[0086] An underwater submersible coordinate system X'Y'Z' can be defined, with the origin at the center of the submersible. The three coordinate axes x', y', and z' point east, north, and vertically upward, respectively. When the underwater submersible is vertical and its heading angle accurately points north, the underwater submersible coordinate system X'Y'Z' coincides with the geodetic coordinate system XYZ. Based on the attitude sensor, real-time attitude data such as roll, pitch, and heading of the underwater submersible are acquired, and a coordinate transformation matrix R is generated. ΨΘΦ =ΨΘΦ.

[0087] Step 22: Calculate the tilt angle of the underwater submersible in the feedback azimuth.

[0088] Once the sonar detects an underwater target and establishes a tracking trajectory for that target, it acquires the target's horizontal azimuth and distance information in real time. With the y-axis pointing north as 0° and clockwise as positive, the target's azimuth α can be selected or entered into the sonar host's display and control interface to set the sonar beam elevation angle at the target's azimuth. For example, the elevation angle η can take values ​​such as -2°, 0°, and 2°. The azimuth vector r2 = (sinα; cosα; tanη) represents the direction of the main lobe of the transmitted beam at the target's azimuth in the current cycle. The angle β between this azimuth vector and the vertical plane X'OY' of the underwater sub-unit is calculated according to formulas (5) to (6).

[0089] Step 23, Delay Generation and Phased Transmission

[0090] The angle β between the main lobe vector of the transmitted beam at the current location of the tracked target and the X'OY' plane of the sonar sub-unit is used as the guiding angle for the phased beam pre-formation of the sonar transmitting transducer array. Phase shift transmission control is performed on each layer of transmitting elements arranged along the z' axis to complete the phased elevation of the omnidirectional transmitted beam.

[0091] Step 24, Multi-period phased beam pitch stabilization

[0092] In the next pulse cycle, steps 21 to 23 are repeated. Based on the real-time updated attitude measurement data and the azimuth information of the tracked target, the transmitter state is adaptively adjusted to ensure that the main lobe of the phased-array elevation beam continuously aims at the tracked target. In step 22, considering the changes in the target trajectory or the vertical gradient of the sound velocity, and based on the A-type display amplitude, B-type display history intensity, and changes in the target echo at different elevation angles in adjacent pulse cycles, the current value of the elevation angle η is changed or reassigned to maximize the signal-to-mixing ratio of the target echo, until the tracked target disappears or a new master control command is received. The implementation process of this invention is illustrated as follows. Figure 6 As shown.

[0093] Those skilled in the art will understand that, besides implementing the system and its various devices, modules, and units provided by this invention in the form of purely computer-readable program code, the same functions can be achieved entirely through logical programming of the method steps, making the system and its various devices, modules, and units of this invention function in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers. Therefore, the system and its various devices, modules, and units provided by this invention can be considered as a hardware component, and the devices, modules, and units included therein for implementing various functions can also be considered as structures within the hardware component; alternatively, the devices, modules, and units for implementing various functions can be considered as both software modules implementing the method and structures within the hardware component.

[0094] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A method for stabilizing the pitch of a suspended sonar transmission beam based on cognitive feedback, characterized in that, Includes the following steps: Step 1: Based on the attitude angle information of the underwater sub-unit, obtain the transformation matrix corresponding to each attitude angle, and establish the vector rotation transformation relationship between the underwater sub-unit coordinate system and the geodetic coordinate system; Step 2: Based on the sonar's detection trajectory of the tracked target, determine the feedback azimuth of the beam pitch stabilization as the azimuth of the tracked target, and calculate the tilt angle of the underwater sub-unit at the feedback azimuth using the azimuth vector of the tracked target in the underwater sub-unit coordinate system. Step 3: Using the tilt angle of the underwater sub-unit in the feedback position of the tracking target as the guiding angle of the phased beam preformation of the sonar transmitting transducer array, phase shift transmission control is performed on each layer of transmitting elements to complete the all-round phased elevation transmission. Step 4: Repeat steps 1 to 3 in a loop. Based on the real-time updated attitude angle measurement data and the azimuth information of the tracked target, adjust the sonar transmission state by tilting the sonar to continuously aim the main lobe of the phased-array pitch transmission beam at the tracked target, thereby achieving multi-cycle phased-array pitch stabilization. Calculate the tilt angle in the feedback azimuth: Once the sonar detects the target and establishes a tracking trajectory for it, the target's location... As feedback azimuth for beam pitch stabilization, if the underwater sub-unit is at a similar depth to the target, the transmitted beam in that azimuth must be kept horizontal. This represents the azimuth vector of the tracked target in the geodetic coordinate system; if the elevation angle of the transmitted beam at that azimuth is... ,but This represents the azimuth vector of the tracked target in the geodetic coordinate system. Expression form in the underwater submachine coordinate system for: （5） Calculate the tilt angle of the underwater submersible at the feedback orientation. for: （6） Wherein, the transformation matrix , , , These are the cosine transform matrices corresponding to the three attitude angles. , These are the analytical expressions of the same spatial vector in the underwater sub-coordinate system and the geodetic coordinate system, respectively.

2. The method for pitch stabilization of a suspended sonar transmission beam based on cognitive feedback according to claim 1, characterized in that, The attitude angle information includes the roll angle, pitch angle, and heading angle of the underwater submersible, obtained from the attitude sensors embedded in the dipping sonar submersible.

3. The method for stabilizing the pitch of a suspended sonar transmission beam based on cognitive feedback according to claim 1, characterized in that, The transformation matrix corresponding to each attitude angle is the cosine transformation matrix corresponding to each attitude angle.

4. The method for pitch stabilization of a suspended sonar transmission beam based on cognitive feedback according to claim 1, characterized in that, The emission elements in each layer are arranged in a direction perpendicular to the horizontal plane.

5. The method for pitch stabilization of a suspended sonar transmission beam based on cognitive feedback according to claim 1, characterized in that, The phase-shift transmission control calculates the phase delay of the transmission pulse of each channel of the sonar transmitting transducer array based on the guiding angle, and controls the phased elevation transmission beam of the transmitting element.

6. The method for pitch stabilization of a suspended sonar transmission beam based on cognitive feedback according to claim 5, characterized in that, The method for calculating the phase delay of the transmitted pulse is as follows: in The value ranges from 1 to N, where N is the number of channels in the sonar transmitting transducer array. The spacing between adjacent channels. To detect the wavelength of the acoustic pulse signal, The tilt angle of the underwater submersible at the feedback orientation.

7. The method for pitch stabilization of a suspended sonar transmission beam based on cognitive feedback according to claim 1, characterized in that, The sonar transmitting transducer array adopts a circumferential omnidirectional transmitting transducer array.

8. The method for pitch stabilization of a suspended sonar transmission beam based on cognitive feedback according to claim 1, characterized in that, If the transmitted beam of the feedback azimuth is kept horizontal, the pitch angle of the tracked target in the direction perpendicular to the horizontal plane in the geodetic coordinate system is 0°. If the difference between the depth of the tracked target and the sonar is large or the sound speed gradient changes greatly, so that the transmitted beam of the feedback azimuth and the tracked target are not in the same horizontal plane, then different pitch stabilization angles of the transmitted beam are set by the sonar display and control console so that the main lobe sound ray of the transmitted beam can continuously point to the tracked target.

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