A Topographic Correction Method for Marine Engineering Mapping Based on Multibeam Bathymetry

Abstract

This invention relates to the field of marine engineering surveying technology, specifically providing a method for topographic correction in marine engineering surveying based on multibeam bathymetry. By synchronously acquiring multi-source data, a ground vibration-sound velocity coupling model is constructed to generate a dynamic sound velocity correction term. Static sound velocity profiles, internal wave disturbance terms, and sound velocity correction terms are fused to establish a spatiotemporally evolving time-shifted sound velocity field. Based on the ship's attitude and the time-shifted sound velocity field, dynamic spatial repositioning calculation is achieved through a dual-axis decoupled rotation matrix. Spatial adaptive filtering technology is employed to suppress tunneling noise. The topographic deformation rate is calculated using continuous periodic data, and a deformation threshold is dynamically set using soil mechanics parameters to trigger graded safety warnings. A high-precision three-dimensional topographic model eliminating sound velocity errors and noise interference is output. This invention solves the problems of insufficient compensation for geological activity interference, inadequate suppression of tunneling noise, and large dynamic environment repositioning errors in traditional surveying, significantly improving the reliability of topographic measurements in complex sea areas.

Description

Technical Field

[0001] This invention relates to the field of marine engineering surveying technology, and specifically to a method for topographic correction in marine engineering surveying based on multibeam bathymetry. Background Technology

[0002] Multibeam bathymetry (MBB) is a high-precision mapping technology that uses shipborne sonar arrays to transmit multiple sound waves to the seabed and retrieves the echo signals to invert the seabed topography. This technology is widely used in engineering fields such as subsea pipeline laying, platform site selection, and channel dredging. Its core advantage lies in its ability to efficiently acquire large-scale, high-resolution three-dimensional seabed topographic data. However, in actual marine environments, existing technologies still face measurement distortion problems caused by multiple interference factors, resulting in three highs and one low defect in traditional mapping data: high noise (tunneling effect causes false undulations in the topographic surface, masking micro-topographic features); high bias (dynamic sound velocity disturbances and ship attitude coupling errors introduce systematic elevation shifts); high latency (deformation risk assessment relies on manual interpretation, resulting in insufficient response speed); and low reliability (low data credibility in complex geological areas, restricting the precise design and safe operation and maintenance of critical projects such as subsea pipelines and anchorages). Specifically, this manifests in the following ways:

[0003] Traditional methods assume a static sound velocity field and rely solely on static sound velocity profiles for ray correction. However, seafloor geological activity causes instantaneous disturbances in water sound velocity. Existing technologies lack mechanisms to perceive and compensate for dynamic sound velocity changes, leading to systematic biases in depth sounding data from complex deep-sea geological areas, severely impacting the accuracy of topographic representation. In side-scan sonar measurements, the tunneling effect caused by multiple reflections from the seabed introduces high-frequency noise into the raw data. Existing filtering methods are mostly empirical post-processing, struggling to distinguish between real micro-topographic features and acoustic artifacts, resulting in blurring or distortion of key structures such as trenches and reef edges, failing to meet the precision requirements of fine engineering projects like pipeline trench inspection. Ship attitude correction typically uses simplified geometric models, neglecting the inter-axis coupling effect of rotation matrices under complex motion; sound velocity correction relies on static profiles, ignoring internal waves and spatiotemporal dynamic disturbances caused by geological activity. Separate processing of these two methods amplifies ray tracking errors, significantly reducing the accuracy of footprint coordinate repositioning. Existing topographic deformation monitoring relies heavily on periodic data comparisons, lacking real-time risk assessment models that integrate soil mechanical parameters. Empirical thresholds cannot dynamically reflect the coupling effect of geological conditions and topographic dip angle, leading to delayed or false landslide warnings and making it difficult to support proactive decision-making for engineering safety and prevention.

[0004] The present invention aims to design a topographic correction method for marine engineering mapping based on multibeam bathymetry to overcome the above-mentioned defects, and realize the technological transformation of marine engineering mapping from static measurement to geological activity perception, dynamic correction and risk prediction. Summary of the Invention

[0005] To address the problems existing in the background art, the present invention provides a method for topographic correction in marine engineering mapping based on multibeam bathymetry, which includes the following steps:

[0006] S1: Multi-source data synchronous acquisition; seabed echo signals are acquired via a shipborne multibeam transducer array; the roll angle output by the ship's attitude instrument is acquired synchronously. Pitch angle heave value Earth's pulsating displacement field was collected using an array of seabed vibration sensors. Static sound velocity profiles were obtained using a sound velocity profiler. ;

[0007] S2: Earth pulsation-sound velocity coupling modeling; calculating the sound velocity correction term based on the earth pulsation displacement field:

[0008] ;

[0009] in This is the correction factor for the speed of sound; The sound velocity-strain coupling coefficient is determined through acoustic experiments on soil. This is ground motion displacement; The operation of finding the derivative of earth pulsations;

[0010] S3: Time-shifted sound velocity field construction; fusion of static sound velocity profile and dynamic correction terms:

[0011] ;

[0012] in For time-shifted sound velocity field; For depth Static sound velocity profile; internal wave This is the sound speed disturbance term caused by internal waves;

[0013] S4: Dynamic spatial repositioning processing; calculation of footprint coordinates based on hull attitude and time-shift sound velocity field.

[0014] ;

[0015] in The footprint coordinates are in the matrix coordinate system; This is the rotation matrix about the X / Y axes; For roll correction angle; For pitch correction angle; These are the measured roll angle and pitch angle, respectively. The distance at which sound rays travel; The beam incidence angle;

[0016] S5: Tunneling effect suppression processing; the following cancellation algorithm is used:

[0017] ;

[0018] in It is an adaptive weight vector; It is the covariance matrix; The guide vector for the desired direction; For the number of snapshots; For the first Each snapshot data vector; Represents the conjugate transpose operator;

[0019] S6: Calculation of terrain deformation rate; Calculation of terrain change rate based on continuous periodic data:

[0020] ;

[0021] in This represents the rate of change of terrain elevation. for Elevation value at any given time; For measurement period;

[0022] S7: Engineering safety early warning; when the rate of change in terrain elevation exceeds the critical threshold, i.e. An alarm will be triggered at any time;

[0023] in The elastic modulus of the soil; The internal friction angle of the soil; This refers to the soil density. The slope angle of the terrain;

[0024] S8: Correct terrain output; generate a 3D terrain model that eliminates tunneling effects and sound speed errors.

[0025] Furthermore, the specific process of S1 includes:

[0026] S1.1: Shipborne multibeam transducer array with pulse repetition frequency Emitting sound waves and receiving echo signals from the seabed ;in:

[0027] The pulse repetition frequency; The pulse period; For the first The time-domain signal of each array element;

[0028] S1.2: The ship's attitude sensor uses a sampling rate Output roll angle Pitch angle heave value ;in:

[0029] The attitude data sampling rate; The angle of rotation about the ship's X-axis; The angle of rotation about the Y-axis of the hull; This refers to the vertical displacement.

[0030] S1.3: The seabed vibration sensor array is arranged in a spatial grid to collect ground pulsation displacement fields. ;in:

[0031] This is ground motion displacement; In planar coordinates; For time; The amplitude; The vibration frequency; Phase angle;

[0032] S1.4: Obtaining static sound velocity profiles using a sound velocity profiler ;in:

[0033] For depth The static speed of sound at that location; Surface sound velocity; The sound speed gradient; For water depth;

[0034] S1.5: Multi-source data time synchronization is achieved through the FPGA-PPS time synchronization module, reducing synchronization error. ;in This is the time synchronization error.

[0035] Furthermore, the specific process of S2 includes:

[0036] S2.1: Earth-moving displacement field Perform time differentiation:

[0037] ;

[0038] in This is a partial differential operator; For time increments;

[0039] S2.2: Calibrate the coupling coefficient through soil acoustic experiments:

[0040] ;

[0041] in The sound velocity-strain coupling coefficient; measured. This refers to the change in sound velocity measured in the laboratory.

[0042] S2.3: Calculate the sound speed correction term:

[0043] ;

[0044] in This is the correction factor for the speed of sound.

[0045] Furthermore, the specific process of S3 includes:

[0046] S3.1: Internal wave disturbance term measured using a CTD sensor:

[0047] ;

[0048] Among them, internal waves The sound speed disturbance caused by internal waves; Temperature coefficient; This refers to the change in temperature. Salinity coefficient; This represents the change in salinity.

[0049] S3.2: Integrating static and dynamic sound velocity components:

[0050] ;

[0051] in This is a time-shifted sound velocity field.

[0052] Furthermore, the specific process of S4 includes:

[0053] S4.1: Calculate the roll correction angle:

[0054] ;

[0055] in This is the equivalent roll rotation angle; It is the arcsine function; It is a sine function; It is a cosine function; This is the measured roll angle; For pitch correction angle;

[0056] S4.2: Calculate the pitch correction angle:

[0057] ;

[0058] in This is the equivalent pitch rotation angle; This is the measured pitch angle;

[0059] S4.3: Construct the rotation matrix:

[0060] ;

[0061] in This is a rotation matrix about the X-axis; This is the rotation matrix around the Y-axis;

[0062] S4.4: Calculate the lower footprint coordinates in the matrix coordinate system:

[0063] ;

[0064] in The coordinates are in the matrix coordinate system; The distance at which sound rays travel; The incident angle of the beam is denoted as .

[0065] Furthermore, the specific process of S5 includes:

[0066] S5.1: Constructing the blocking matrix:

[0067] ;

[0068] in For blocking matrices; It is the identity matrix; For guiding vector; The mirror beam angle; It is the conjugate transpose operator; Norm operators;

[0069] S5.2: Calculate the adaptive weight vector:

[0070] ;

[0071] in It is an adaptive weight vector; It is the covariance matrix; For the first Each snapshot data vector; For the number of snapshots; The matrix inversion operator;

[0072] S5.3: Output beam after sidelobe suppression:

[0073] ;

[0074] in For output signal; The input signal vector.

[0075] Furthermore, the specific process of S6 includes:

[0076] S6.1: Spatiotemporal registration of continuous periodic bathymetry data:

[0077] ;

[0078] in This represents the change in elevation. for Elevation at any moment; For measurement intervals;

[0079] S6.2: Calculate the deformation rate field:

[0080] ;

[0081] in denoted as the deformation rate.

[0082] Furthermore, the specific process of S7 includes:

[0083] S7.1: Calculate the critical shear strength of the soil:

[0084] ;

[0085] in It is the critical shear strength; For effective cohesion; Effective normal stress; The effective internal friction angle;

[0086] S7.2: Establishing a deformation rate threshold model:

[0087] ;

[0088] in The deformation rate threshold; The elastic modulus of the soil; This refers to the soil density. The slope angle of the terrain;

[0089] S7.3: Trigger a tiered alert:

[0090] .

[0091] Furthermore, the specific process of S8 includes:

[0092] S8.1: Generate a 3D terrain model:

[0093] ;

[0094] in The corrected elevation; For tide level correction; This is the correction amount for the sound speed error;

[0095] S8.2: Calculate the slope field:

[0096] ;

[0097] in This is the gradient operator.

[0098] This invention also provides a marine engineering mapping topography correction system based on multibeam bathymetry, comprising:

[0099] The shipborne multibeam transducer array is installed at the bottom of the survey vessel and connected to the input of the dynamic spatial positioning processing unit and the tunneling effect suppression processing unit via data cables.

[0100] The ship attitude instrument is fixed to the deck of the measuring ship and connected to the input end of the dynamic space positioning processing unit through a data interface;

[0101] The seabed vibration sensor array is deployed at the location of the seabed spatial grid and connected to the input end of the ground vibration-sound velocity coupling modeling unit via underwater cables;

[0102] The sound velocity profiler is suspended in the water below the measuring vessel and connected to the input of the time-shifted sound velocity field construction unit via a signal line;

[0103] The CTD sensor, deployed coaxially with the sound velocity profiler, is connected to the input of the time-shifted sound velocity field construction unit via a shared data bus;

[0104] The FPGA-PPS timing module is integrated into the control cabin of the survey vessel. Its clock output is connected to the clock interfaces of the shipborne multibeam transducer array, ship attitude instrument, seabed vibration sensor array, sound velocity profiler and CTD sensor through synchronization signal lines.

[0105] The ground vibration-sound velocity coupling modeling unit is deployed in the shipboard processing industrial control computer. Its input end receives data from the seabed vibration sensor array, and its output end is connected to the correction input port of the time-shifted sound velocity field construction unit through a data bus.

[0106] The time-shifted sound velocity field construction unit is integrated into the shipborne processing industrial control computer. Its static sound velocity input terminal is connected to the sound velocity profiler, its internal wave disturbance input terminal is connected to the CTD sensor, its correction input terminal is connected to the ground pulsation-sound velocity coupling modeling unit, and its output terminal is connected to the sound velocity input port of the dynamic space repositioning processing unit through a high-speed data channel.

[0107] The dynamic spatial positioning processing unit runs on the shipborne industrial control computer. Its attitude data input end is connected to the ship's attitude instrument, its sound velocity field input end is connected to the time-shifted sound velocity field construction unit, its beam data input end is connected to the tunnel effect suppression processing unit, and its coordinate output end is connected to the terrain deformation rate calculation unit through a data link.

[0108] The tunnel effect suppression processing unit has a built-in multi-beam signal processing board. Its original signal input end is connected to the shipborne multi-beam transducer array, and the suppressed signal output end is connected to the dynamic space repositioning processing unit through the board interface.

[0109] The terrain deformation rate calculation unit is deployed on the data processing server. Its input end receives the elevation coordinates output by the dynamic spatial positioning processing unit, and the change rate output end is connected to the monitoring interface of the engineering safety early warning unit through the network.

[0110] The engineering safety early warning unit is integrated into the monitoring platform. Its terrain deformation rate input terminal is connected to the terrain deformation rate calculation unit, and its early warning signal output terminal is connected to the corrected terrain output unit through the alarm bus.

[0111] The terrain output unit is deployed on a graphics workstation. Its terrain data input end receives the three-dimensional coordinates from the dynamic spatial positioning processing unit, its early warning status input end is connected to the engineering safety early warning unit, and its output end is connected to the display terminal to generate a three-dimensional terrain model.

[0112] The beneficial effects achieved by this invention are as follows:

[0113] This invention, based on a graded alarm mechanism using a deformation rate threshold model, dynamically calculates critical shear strength using topographic mechanical parameters, enabling a shift from empirical judgment to quantitative assessment of geological risks. This invention transforms raw, disturbed data into a high-precision topographic model usable in engineering, meeting the accuracy requirements of complex engineering projects such as subsea pipeline laying. It establishes a measurement-correction-early warning safety control system, providing core technical support for marine engineering. Specifically:

[0114] First, this invention constructs a dynamic coupling model of ground vibration and sound velocity. By capturing the ground vibration displacement field in real time through a seabed vibration sensor array, and combining the coupling coefficient calibrated by the acoustics of the soil, a quantitative compensation mechanism for geological micro-vibration and sound velocity disturbance is established. This breakthrough solves the problem of ignoring the influence of seabed geological activity on sound velocity in traditional surveying. Through displacement field time differential operation and sound velocity correction term generation, dynamic elimination of ground vibration interference is achieved, upgrading the static sound velocity assumption to a geological activity-sensing sound velocity model, which significantly improves the measurement reliability of complex geological areas in the deep sea.

[0115] Secondly, this invention designs an adaptive tunneling effect suppression method, introducing spatial filtering from the radar field into acoustic mapping. By constructing a blocking matrix to filter out mirror interference and using the inverse of the covariance matrix to calculate the optimal weight vector, it effectively overcomes the problem of multiple seabed reflections unique to side-scan sonar. This method abandons traditional empirical filtering methods and directly suppresses acoustic interference sources through spatial signal processing. While maintaining the integrity of topographic features, it eliminates high-frequency noise, resulting in a qualitative improvement in the identification of seabed micro-topographic features. It is particularly suitable for the detailed mapping of critical structures such as pipelines and trenches.

[0116] Third, this invention proposes a four-dimensional time-shifting sound velocity field construction and dynamic spatial positioning method. By integrating static sound velocity profiles, internal wave disturbance terms, and ground pulsation correction terms, a spatiotemporally dynamic sound velocity model is established. Combined with an original dual-axis decoupling algorithm, the ship's roll and pitch are transformed into independent rotation matrices, achieving accurate footprint positioning under complex motion. This simultaneously solves the two major problems of water environment disturbance and ship attitude interference, enabling the sound ray tracking accuracy to leap from planar correction to spatiotemporal four-dimensional correction, and changing the traditional spatial positioning method of multibeam bathymetry. Attached Figure Description

[0117] Figure 1 This is a flowchart of the marine engineering mapping topography correction method based on multibeam bathymetry of the present invention;

[0118] Figure 2 This is a functional framework diagram of a marine engineering mapping and topographic correction system based on multibeam bathymetry;

[0119] Figure 3 These are the original and corrected topographic maps generated in Example 1. The original topographic map shows uncorrected multibeam bathymetry data, presenting rough seabed topographic features including ground vibration interference and tunneling effect noise. The corrected topographic map shows the topographic results after sound velocity error compensation and tunneling effect suppression.

[0120] Figure 4 This is an error diagram between the corrected terrain and the actual terrain in Example 1. Detailed Implementation

[0121] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. In addition, the forms of the various structures described in the following embodiments are merely illustrative. The present invention is not limited to the structures described in the following embodiments. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0122] Reference Figures 1-4This invention designs a marine engineering mapping topography correction system based on multibeam echo sounding, consisting of multiple sets of physical equipment and processing units. These structures are deployed hierarchically on the survey vessel, underwater, and control center. The shipborne area includes: a multibeam transducer array, a ship attitude instrument, an FPGA-PPS timing module, and an industrial control computer, containing a dynamic spatial positioning unit, a tunneling effect suppression unit, and a sound velocity modeling unit. The underwater area includes: a seabed vibration sensor array, a sound velocity profiler, and a CTD sensor. The shore-based control center area includes: a data processing server for calculating topography deformation rate, an alarm server, and a graphics workstation for correcting topography output.

[0123] The shipborne multibeam transducer array is installed at the keel position on the bottom of the survey vessel. It is connected via armored data cables to the beam data input port of the dynamic spatial positioning processing unit and the raw signal input port of the tunneling effect suppression processing unit, respectively, for emitting sound waves and acquiring raw seabed echo signals. The attitude instrument is fixed at the center of gravity of the survey vessel's deck and is directly connected to the attitude data input port of the dynamic spatial positioning processing unit via a waterproof data interface, transmitting roll, pitch, and heave values ​​in real time.

[0124] The underwater sensing equipment is deployed via a dedicated carrier: the seabed vibration sensor array is laid out on the seabed in a 50m×50m spatial grid and connected to the displacement signal input port of the ground pulsation-sound velocity coupling modeling unit via tensile underwater cables to capture the ground pulsation displacement field; the sound velocity profiler and CTD sensor are coaxially suspended 10m below the hull and connected in parallel to the time-shifted sound velocity field construction unit via shielded signal lines and data buses, respectively. The sound velocity profiler is connected to the static sound velocity input port, and the CTD sensor is connected to the internal wave disturbance input port.

[0125] The core of the time synchronization is the FPGA-PPS timing module, which is integrated into the main cabinet of the control room of the survey vessel. Its clock output is connected to the PPS clock interface of the shipborne multibeam transducer array, ship attitude instrument, seabed vibration sensor array, sound velocity profiler and CTD sensor through five synchronization signal lines, ensuring that the timestamp error of all data is ≤1ms.

[0126] The ground vibration-sound velocity coupling modeling unit and the time-shifting sound velocity field construction unit are integrated in the same processing slot of the shipboard industrial control computer, and the two interact through the backplane data bus. The input end of the ground vibration-sound velocity coupling modeling unit receives displacement data from the seabed vibration sensor array, and the output end is directly connected to the correction input port of the time-shifting sound velocity field construction unit through the internal bus. The output end of the time-shifting sound velocity field construction unit is connected to the sound velocity input port of the dynamic space repositioning processing unit through the PCIe high-speed channel.

[0127] The tunneling effect suppression processing unit is built into the FPGA chip of the multi-beam signal processing board. Its original signal input terminal is directly connected to the shipborne multi-beam transducer array through the onboard circuit, and the suppressed signal output terminal is connected to the beam data input port of the dynamic spatial positioning processing unit through the LVDS interface between the boards.

[0128] The dynamic spatial positioning processing unit runs on the main processor of the shipborne industrial control computer and receives four types of inputs: ship attitude data, time-shifted sound velocity field data, beam signal after tunneling effect suppression, and time synchronization signal from the timing module; its coordinate output is connected to the input buffer of the terrain deformation rate calculation unit via gigabit Ethernet.

[0129] The terrain deformation rate calculation unit runs on the data processing server. It receives the elevation coordinate sequence output by the dynamic spatial positioning processing unit through the fiber optic network, calculates the deformation rate field, and then transmits it to the monitoring interface of the engineering safety early warning unit via the TCP / IP protocol.

[0130] The engineering safety early warning unit is integrated into the alarm server of the monitoring platform. When the deformation rate exceeds the critical threshold calculated by the soil mechanical parameters, it sends a graded alarm signal to the corrected terrain output unit through the RS485 alarm bus.

[0131] The terrain correction output unit is deployed on a graphics workstation. Its terrain data input end receives the three-dimensional coordinates of the dynamic spatial positioning processing unit through DisplayPort, and the early warning status input end parses the alarm signal of the engineering safety early warning unit. Finally, it outputs to the display terminal through the HDMI interface to render the three-dimensional terrain model, slope map and dynamic risk heat map.

[0132] In this system, shipborne and underwater sensors form a physical sensing network, achieving microsecond-level synchronization under the control of the FPGA-PPS timing module; the shipborne industrial control computer completes sound speed correction, geometric positioning, and signal optimization; the shore-based server calculates the terrain deformation rate and triggers threshold alarms; and the graphics workstation integrates geometric coordinates and alarm status to generate engineering safety visualization products.

[0133] The process chain is as follows: from the seabed vibration sensor array to the underwater cable, to the ground pulsation-sound velocity coupling modeling unit, to the backplane bus, to the time-shifted sound velocity field construction unit, to the PCIe channel, to the dynamic spatial positioning processing unit; the tunneling effect suppression chain is as follows: from the shipborne multibeam transducer array to the onboard circuit, to the tunneling effect suppression processing unit, to the LVDS interface, to the dynamic spatial positioning processing unit; the dynamic spatial positioning processing unit is as follows: from the Ethernet, to the terrain deformation rate calculation unit, to TCP / IP, to the engineering safety early warning unit, to the RS485 bus, to the terrain correction output unit.

[0134] Based on the above system, this invention also designs a marine engineering mapping topography correction method based on multibeam bathymetry, which includes the following steps:

[0135] S1: Multi-source data synchronous acquisition; seabed echo signals are acquired via a shipborne multibeam transducer array; the roll angle output by the ship's attitude instrument is acquired synchronously. Pitch angle heave value Earth's pulsating displacement field was collected using an array of seabed vibration sensors. Static sound velocity profiles were obtained using a sound velocity profiler. ;

[0136] S2: Earth pulsation-sound velocity coupling modeling; calculating the sound velocity correction term based on the earth pulsation displacement field:

[0137] ;

[0138] in This is the sound speed correction amount (m / s); The sound velocity-strain coupling coefficient (m² / s) is determined through acoustic experiments on soil. The displacement due to ground pulsation (m); The operation of finding the derivative of earth pulsations;

[0139] S3: Time-shifted sound velocity field construction; fusion of static sound velocity profile and dynamic correction terms:

[0140] ;

[0141] in The time-shifted sound velocity field (m / s); For depth Static sound velocity profile (m / s); internal wave The sound velocity disturbance term caused by internal waves (m / s);

[0142] S4: Dynamic spatial repositioning processing; calculation of footprint coordinates based on hull attitude and time-shift sound velocity field.

[0143] ;

[0144] in The footprint coordinates (m) are in the matrix coordinate system. This is the rotation matrix about the X / Y axes; For the roll correction angle (°); For the pitch correction angle (°); These are the measured roll angle and pitch angle (°); The distance the sound ray travels (m); The beam incidence angle is (°).

[0145] S5: Tunneling effect suppression processing; the following cancellation algorithm is used:

[0146] ;

[0147] in It is an adaptive weight vector; It is the covariance matrix; The guide vector for the desired direction; For the number of snapshots; For the first Each snapshot data vector; Represents the conjugate transpose operator;

[0148] S6: Calculation of terrain deformation rate; Calculation of terrain change rate based on continuous periodic data:

[0149] ;

[0150] in The rate of change of terrain elevation (m / s); for Elevation value at any given time (m); The measurement period is in seconds.

[0151] S7: Engineering safety early warning; when the rate of change in terrain elevation exceeds the critical threshold, i.e. An alarm will be triggered at any time;

[0152] in The elastic modulus of soil (kPa); The internal friction angle of the soil (°); Soil density (kg / m³); The terrain inclination angle (°);

[0153] S8: Correct terrain output; generate a 3D terrain model that eliminates tunneling effects and sound speed errors.

[0154] The specific process of S1 includes:

[0155] 1.1: Shipborne multibeam transducer array with pulse repetition frequency Emitting sound waves and receiving echo signals from the seabed ;in:

[0156] The pulse repetition frequency (Hz); The pulse period is (s). For the first The time-domain signal (V) of each array element;

[0157] 1.2: The ship's attitude sensor uses a sampling rate Output roll angle Pitch angle heave value ;in:

[0158] The attitude data sampling rate (Hz); The angle of rotation (°) around the ship's X-axis; The angle of rotation (°) around the Y-axis of the ship's hull; The vertical displacement is expressed in meters (m).

[0159] 1.3: The seabed vibration sensor array is deployed according to a spatial grid to collect the ground pulsation displacement field. ;in:

[0160] The displacement due to ground pulsation (m); For plane coordinates (m); Time (s); The amplitude is (m). The vibration frequency (Hz); Phase angle (rad);

[0161] 1.4: Obtaining Static Sound Velocity Profiles with a Sound Velocity Profiler ;in:

[0162] For depth The static speed of sound at that location (m / s); Surface sound velocity (m / s); The sound speed gradient is (s⁻²). Water depth (m);

[0163] 1.5: Multi-source data time synchronization is achieved through the FPGA-PPS time synchronization module, reducing synchronization errors. ;in The time synchronization error is (s).

[0164] 3. A method for topographic correction in marine engineering mapping based on multibeam bathymetry, characterized in that the specific process of S2 includes:

[0165] 2.1: Earth-based pulsating displacement field Perform time differentiation:

[0166] ;

[0167] in This is a partial differential operator; The time increment is (s);

[0168] 2.2: Calibration of coupling coefficients through soil acoustic experiments:

[0169] ;

[0170] in The sound velocity-strain coupling coefficient (m² / s); Measured The measured change in sound velocity (m / s) in the laboratory.

[0171] 2.3: Calculate the sound speed correction term:

[0172] ;

[0173] in This is the sound speed correction factor (m / s).

[0174] The specific process of S3 includes:

[0175] 3.1: Measurement of internal wave disturbance term using a CTD sensor:

[0176] ;

[0177] Among them, internal waves The sound speed disturbance (m / s) caused by internal waves; Temperature coefficient; The change in temperature (°C); Salinity coefficient; The change in salinity (psu);

[0178] 3.2: Integrating static and dynamic sound velocity components:

[0179] ;

[0180] in The sound velocity field is time-shifted (m / s).

[0181] The specific process of S4 includes:

[0182] 4.1: Calculate the roll correction angle:

[0183] ;

[0184] in The equivalent roll rotation angle (°); It is the arcsine function; It is a sine function; It is a cosine function; The measured roll angle is (°). For the pitch correction angle (°);

[0185] 4.2: Calculate the pitch correction angle:

[0186] ;

[0187] in Equivalent pitch rotation angle (°); The measured pitch angle (°);

[0188] 4.3: Constructing the rotation matrix:

[0189] ;

[0190] in This is a rotation matrix about the X-axis; This is the rotation matrix around the Y-axis;

[0191] 4.4: Calculate the footprint coordinates in the matrix coordinate system:

[0192] ;

[0193] in The coordinates are in the matrix coordinate system (m). The distance the sound ray travels (m); The beam incidence angle is (°).

[0194] The specific process of S5 includes:

[0195] 5.1: Constructing the blocking matrix:

[0196] ;

[0197] in For blocking matrices; It is the identity matrix; For guiding vector; The mirror beam angle (°); It is the conjugate transpose operator; Norm operators;

[0198] 5.2: Calculate the adaptive weight vector:

[0199] ;

[0200] in It is an adaptive weight vector; It is the covariance matrix; For the first Each snapshot data vector; For the number of snapshots; The matrix inversion operator;

[0201] 5.3: Output beam after sidelobe suppression:

[0202] ;

[0203] in For output signal; The input signal vector.

[0204] The specific process of S6 includes:

[0205] 6.1: Spatiotemporal registration of continuous periodic bathymetry data:

[0206] ;

[0207] in Elevation change (m); for Elevation at any moment (m); The measurement interval is (s).

[0208] 6.2: Calculation of the deformation rate field:

[0209] ;

[0210] in The deformation rate is denoted as (m / s).

[0211] The specific process of S7 includes:

[0212] 7.1: Calculation of critical shear strength of soil:

[0213] ;

[0214] in Critical shear strength (kPa); Effective cohesion (kPa); Effective normal stress (kPa); The effective internal friction angle (°);

[0215] 7.2: Establishing a deformation rate threshold model:

[0216] ;

[0217] in The deformation rate threshold (m / s); The elastic modulus of soil (kPa); Soil density (kg / m³); The terrain inclination angle (°);

[0218] 7.3: Triggering a tiered alert: .

[0219] The specific process of S8 includes:

[0220] 8.1: Generating a 3D terrain model:

[0221] ;

[0222] in The corrected elevation (m); Tide level correction (m); The sound velocity error correction amount (m);

[0223] 8.2: Calculation of the slope field:

[0224] ;

[0225] in This is the gradient operator.

[0226] Example 1: This example focuses on a seabed topographic mapping scenario near an offshore oil platform. The area is currently undergoing a subsea pipeline laying project and has the following environmental characteristics: there are weak geothermal pulsations caused by geological tectonic activity on the seabed; there are internal wave activities in the water body causing sound speed disturbances; the survey vessel is affected by sea conditions, resulting in roll and pitch; and there is tunneling interference in side-scan sonar measurements.

[0227] The specific implementation process of Embodiment 1 of the present invention is as follows:

[0228] Shipborne multi-beam transducer array with pulse repetition frequency Emitting sound waves ( (with pulse period), receiving seabed echo signals. ( (Numbering of array elements).

[0229] The ship's attitude sensor outputs the roll angle in real time at a sampling rate of 100 Hz. (about the ship's X-axis), pitch angle (around the Y-axis) and heave value (Vertical displacement).

[0230] The seabed vibration sensor array is arranged in a 50 m × 50 m spatial grid to collect ground vibration displacement fields. ,in For amplitude, The vibration frequency, This is the phase angle.

[0231] Acquiring static sound velocity profiles using a sound velocity profiler ;

[0232] Synchronization control: Synchronization pulses are sent to all devices via the FPGA-PPS timing module to ensure timestamp accuracy. ms.

[0233] For displacement field Perform time differentiation:

[0234]

[0235] Coupling coefficient calibration: The change in sound velocity was measured through soil acoustic experiments. Calculate coefficients .

[0236] Generate sound speed correction term:

[0237]

[0238] Internal wave disturbances are measured using a coaxially deployed CTD sensor.

[0239]

[0240] By integrating static and dynamic components, a four-dimensional sound velocity field is constructed:

[0241]

[0242] Calculate the equivalent rotation angle:

[0243]

[0244] Construct the rotation matrix:

[0245]

[0246] Calculate the footprint coordinates in the matrix coordinate system:

[0247]

[0248] Construct a blocking matrix to filter out mirror interference:

[0249]

[0250] The desired direction guide vector, The mirror beam angle;

[0251] Calculate the covariance matrix ( (Number of snapshots).

[0252] Solving for the adaptive weight vector:

[0253]

[0254] Output suppressed signal: .

[0255] Elevation data for continuous periods Perform spatiotemporal registration:

[0256]

[0257] Calculate the deformation rate field:

[0258]

[0259] Calculate the critical shear strength of the soil:

[0260]

[0261] Set the deformation rate threshold:

[0262]

[0263] Tiered alarm triggering:

[0264] like An orange alert has been triggered.

[0265] like Red alert triggered.

[0266] Generate a 3D terrain model:

[0267]

[0268] Calculate the slope field: .

[0269] Figure 3 These are the original and corrected topographic maps generated in Example 1. The original topographic map shows uncorrected multibeam bathymetry data, presenting rough seabed topographic features including ground pulsation interference and tunneling effect noise. The corrected topographic map shows the topographic results after sound velocity error compensation and tunneling effect suppression. Figure 4 This is an error map of the original measured terrain and the corrected terrain in Example 1.

[0270] from Figure 3 The original topographical measurements show the following characteristics: the overall elevation is approximately 0.1–0.3 m higher than the actual elevation, with the largest deviation in the central area; there is significant high-frequency noise with a standard deviation of 2 m, giving the surface a "sandpaper" texture; the central depression is masked by noise, and the boundaries are blurred; the maximum elevation reaches 62 m, exceeding the actual topographical range by 0–50 m. Specifically:

[0271] The central area at coordinates 100,100 exhibits a distinct concave feature. The overall surface distribution resembles a Gaussian surface, but it is rough and uneven. The elevation range abnormally extends to 0-62m, exceeding the actual terrain range.

[0272] There is a distinct "sandpaper-like" textured high-frequency noise. The noise is evenly distributed and unaffected by terrain features. The maximum noise amplitude is approximately ±4m, as judged by the degree of surface undulation.

[0273] The overall elevation is too high, especially in the central depression area. The boundaries are blurred, and the actual depression boundaries are difficult to identify. The color distribution shows that the central area is "overheated" and has a reddish tinge.

[0274] This indicates the presence of tunneling effect interference, and the high-frequency noise conforms to the characteristics of multiple reflections in side-scan sonar. The noise amplitude σ=2m is consistent with the typical interference level in marine mapping.

[0275] The sound velocity error causes a systematic deviation, and the overall elevation shift conforms to the sound velocity variation pattern caused by ground pulsation. The maximum shift in the central region is approximately 0.3m, estimated from the color gradient.

[0276] Uncorrected data does not meet engineering requirements; noise obscures key terrain features such as pipeline trenches; elevation errors exceed the safety threshold (>±0.5m); and blurred boundaries negatively impact engineering decisions.

[0277] The corrected terrain has the following characteristics: Elevation restoration: The overall elevation returns to the true level, and systematic biases are eliminated; Smooth surface: High-frequency noise is effectively suppressed, and the surface exhibits smooth characteristics; Clear features: The central depression structure is clearly visible, and the boundaries are well-defined; Normal elevation range: The maximum elevation is 51m, close to the extreme value of the true terrain; Specifically, it is manifested in:

[0278] The central depression is clearly visible. The boundaries are well-defined, and the curvature is continuous and smooth. The elevation range has returned to normal (0-51m). The surface "sandpaper-like" texture has largely disappeared, with only slight undulations (<0.5m) remaining. The sharpness of the terrain outline has improved. The steep slope features at the depression edge are fully preserved. The surface curvature changes naturally and continuously. There is no loss of features due to excessive smoothing. This indicates that the systematic deviation has been completely eliminated, and the elevation of the central area has been restored to the 50m benchmark value. This meets the theoretical expectations of steps S2-S3. The tunnel effect has been successfully suppressed, with a high-frequency noise filtering rate >90%. Key terrain features have been preserved, achieving the technical objectives of step S5. Simultaneously, the elevation error is <±0.5m, improving the recognizability of terrain features and meeting the requirements for marine engineering safety monitoring.

[0279] from Figure 4The results show: Blue area (negative deviation): the corrected terrain is slightly lower than the true value (maximum -1.5m); Red area (positive deviation): the corrected terrain is slightly higher than the true value (maximum +1.8m); Error distribution: the error is larger in the central area and smaller in the peripheral areas; Error range: the overall error is within ±1.5m, with a standard deviation of approximately 0.8m. Specifically:

[0280] The maximum error is ±1.5m in the central area. The minimum error is <±0.3m in the edge area. The errors are centrally symmetrically distributed. The negative deviations in the blue area are concentrated at the bottom of the depression. The positive deviations in the red area are distributed in the slope transition zone. There is no obvious directional deviation pattern. The average absolute error is approximately 0.8m. The standard deviation is 0.6m. The maximum error is 1.8m.

[0281] The larger error in the central region indicates that it stems from incomplete compensation of internal wave disturbances. The error in the slope region reflects the nonlinear effect of sound ray bending. The error is positively correlated with terrain complexity. Error in flat areas is <0.5m. Error in steep slope areas is >1.0m.

[0282] This embodiment demonstrates that the method of the present invention successfully eliminates systematic elevation deviations caused by seabed micro-vibrations, making topographic measurement results more accurate. The tunnel effect suppression technology effectively filters out the multiple reflection interference unique to side-scan sonar measurements, significantly improving the smoothness of the topographic surface. The combined application of these two core technologies greatly improves the overall accuracy of seabed topographic data, transforming previously unusable coarse data due to severe interference into reliable data that meets engineering requirements. The corrected topographic data reaches the accuracy standards required for fine engineering projects such as subsea pipeline laying, and key topographic features, including the identification of central depression areas, are significantly improved to a practical level that can be directly applied.

[0283] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for correcting a surveyed topography of an oceanographic project based on multi-beam bathymetry, characterized in that, It includes the following steps: S1: Multi-source data synchronous acquisition; Collecting the sea bottom echo signal through the shipborne multi-beam transducer array; Synchronously acquiring the roll angle , pitch angle , heave value output by the ship attitude instrument ; Collecting the ground pulsation displacement field through the sea bottom vibration sensor array ; Obtaining the static sound speed profile through the sound speed profiler ; S2: Ground microseism-acoustic velocity coupling modeling; Calculate the acoustic velocity correction term according to the ground microseism displacement field: ； wherein is a sound speed correction; is a sound speed-strain coupling coefficient, calibrated by soil acoustic experiments; is a ground microseismic displacement; is a ground microseismic derivative operation; S3: Time-shifted acoustic velocity field construction; Fusion of static acoustic velocity profile and dynamic correction term: ； where is the time-shifted velocity field; is the depth of the static sound speed profile; is the sound speed perturbation term due to the internal wave; S4: Dynamic spatial homing processing; Calculate the footprint coordinates based on the ship attitude and time-shifted acoustic velocity field: ； wherein is the footprint coordinate in the base coordinate system; is the rotation matrix around the X / Y axis; is the roll correction angle; is the pitch correction angle; are the measured roll and pitch angles, respectively; is the sound ray propagation distance; is the beam incidence angle; S5: Tunnel effect suppression processing; The following cancellation algorithm is used: ； wherein is an adaptive steering vector; is a covariance matrix; is an expected direction steering vector; is a number of snapshots; is a snapshot data vector; is a snapshot data vector; denotes a conjugate transpose operator; is a mirror angle; S6: Topographic deformation rate calculation; Calculate the topographic change rate based on continuous period data: ； wherein is a terrain elevation rate of change; is a terrain elevation rate of change; is a terrain elevation rate of change; is a measurement period; S7: engineering safety warning; when the terrain elevation rate of change exceeds the critical threshold, i.e. , an alarm is triggered; wherein is the deformation rate threshold; ; wherein, is the elastic modulus of the soil; is the internal friction angle of the soil; is the density of the soil; is the terrain inclination angle; S8: Corrected terrain output; Generate a three-dimensional terrain model that eliminates tunnel effects and acoustic velocity errors.

2. The multi-beam bathymetry based mapping terrain correction method for ocean engineering according to claim 1, wherein, The specific process of S1 includes: S1.1: The ship-borne multi-beam transducer array emits acoustic pulses at a pulse repetition frequency transmits acoustic waves and receives seabed echo signals ; wherein: for a pulse repetition frequency; for a pulse period; for a time-domain signal of the mth element; S1.2: Ship attitude instrument at attitude data sampling rate output roll angle output pitch angle output heave value ; S1.3: The array of seafloor vibration sensors is laid out in a spatial grid to collect the ground-pulse displacement field ; wherein: is the ground motion displacement; is the plan coordinate; is the time; is the amplitude; is the vibration frequency; is the phase angle; S1.4: The static sound speed profile is obtained by the sound speed profiler ; wherein: For a depth of static sound speed; For a surface sound speed; For a sound speed gradient; For a water depth; S1.5: Multi-source data time synchronization is realized through the FPGA-PPS time service module, and the synchronization error ; wherein is the time synchronization error.

3. The multi-beam bathymetry based mapping terrain correction method for ocean engineering according to claim 1, wherein, The specific process of S2 includes: S2.1: The Earth's Pulsating Displacement Field Take the time derivative: ； wherein is a partial differential operator; is a time increment; S2.2: Coupling coefficient calibration through soil acoustic experiment: ； wherein is the speed of sound-strain coupling coefficient; measured is the measured change in speed of sound in the laboratory; S2.3: Calculate the acoustic velocity correction term: ； wherein is a sound speed correction.

4. The multi-beam bathymetry-based offshore engineering mapping terrain correction method according to claim 1, wherein, The specific process of S3 includes: S3.1: Measure the internal wave disturbance term using a CTD sensor: ； wherein c is the sound speed in the water column; is the sound speed perturbation due to the internal wave; is the temperature coefficient; is the temperature change; is the salinity coefficient; is the salinity change; S3.2: Fusion of static and dynamic acoustic velocity components: ； wherein is the time-lapse acoustic velocity field.

5. The multi-beam bathymetry-based offshore engineering mapping terrain correction method according to claim 1, wherein, The specific process of S4 includes: S4.1: Calculate the roll correction angle: ； wherein is the equivalent roll rotation angle; is the inverse sine function; is the sine function; is the cosine function; is the measured roll angle; is the pitch correction angle; S4.2: Calculate the pitch correction angle: ； wherein is the equivalent pitch rotation angle; is the measured pitch angle; S4.3: Construct a rotation matrix: ； wherein R is a rotation matrix about the X axis; R is a rotation matrix about the Y axis; S4.4: Calculate the footprint coordinates in the base matrix coordinate system: ； wherein is the base array coordinate system coordinate; is the sound ray propagation distance; is the beam incidence angle.

6. The multi-beam bathymetry-based offshore engineering mapping terrain correction method according to claim 1, wherein, The specific process of S5 includes: S5.1: Construct a blocking matrix: ； wherein is a blocking matrix; is an identity matrix; is a steering vector; is a mirror angle; is a conjugate transpose operator; is a norm operator; S5.2: Calculate the adaptive weight vector: ； in It is an adaptive weight vector; It is the covariance matrix; For the first Each snapshot data vector; For the number of snapshots; The matrix inversion operator; S5.3: Output the sidelobe-suppressed beam: ； wherein is an output signal; is an input signal vector.

7. The multi-beam bathymetry-based offshore engineering mapping terrain correction method according to claim 1, wherein, The specific process of S6 includes: S6.1: Time and space registration of continuous period sounding data: ； wherein is the change in elevation; is the time of day elevation; is the time of day elevation; is the measurement interval; S6.2: Calculate the deformation rate field: ； wherein is the rate of deformation.

8. The multi-beam bathymetry-based offshore engineering mapping terrain correction method of claim 1, wherein, The specific process of S7 includes: S7.1: Calculate the critical shear strength of the soil: ； wherein is the critical shear strength; is the effective cohesion; is the effective normal stress; is the effective internal friction angle; S7.2: Establish a deformation rate threshold model: ； wherein, E is the soil elastic modulus; is the soil internal friction angle; is the soil density; is the terrain inclination angle; S7.3: Trigger hierarchical alarms: 。 9. The multi-beam bathymetry-based offshore engineering mapping terrain correction method of claim 1, wherein, The specific process of S8 includes: S8.1: Generate a three-dimensional terrain model: ； wherein is the corrected height; is the tide correction; is the sound speed error correction; S8.2: Calculate the slope field: ； wherein is the gradient operator.

10. System for implementing the method for correcting the mapping of the seabed topography of an oceanographic work based on multibeam bathymetry according to any one of claims 1 to 9, characterized in that, It includes: A shipboard multi-beam transducer array is installed at the bottom of the survey ship and connected through a data cable to the input terminals of the dynamic spatial homing processing unit and the tunnel effect suppression processing unit. A ship attitude instrument is fixed on the deck of the survey ship and connected through a data interface to the input terminal of the dynamic spatial homing processing unit. An array of seabed vibration sensors is arranged at grid locations on the seabed and connected through underwater cables to the input terminals of the ground microseism-acoustic velocity coupling modeling unit. An acoustic velocity profiler is suspended in the water below the survey ship and connected through a signal line to the input terminal of the time-shifted acoustic velocity field construction unit. A CTD sensor is coaxially deployed with the acoustic velocity profiler and connected through a shared data bus to the input terminal of the time-shifted acoustic velocity field construction unit. An FPGA-PPS timekeeping module is integrated in the control cabin of the survey ship, with its clock output terminals connected through synchronization signal lines to the clock interfaces of the shipboard multi-beam transducer array, the ship attitude instrument, the array of seabed vibration sensors, the acoustic velocity profiler, and the CTD sensor. The ground microseism-acoustic velocity coupling modeling unit is deployed in the shipboard processing industrial computer, with its input terminals receiving data from the array of seabed vibration sensors and its output terminals connected through a data bus to the correction input port of the time-shifted acoustic velocity field construction unit. The time-shifted sound velocity field construction unit is integrated in a ship-mounted processing industrial computer, a static sound velocity input end of which is connected with a sound velocity profiler, an internal wave disturbance input end of which is connected with a CTD sensor, a correction amount input end of which is connected with a ground pulsation-sound velocity coupling modeling unit, and an output end of which is connected with a sound velocity input port of a dynamic space homing processing unit through a high-speed data channel; The dynamic space homing processing unit is operated in a ship-mounted processing industrial computer, a posture data input end of which is connected with a ship posture instrument, a sound velocity field input end of which is connected with the time-shifted sound velocity field construction unit, and a wave beam data input end of which is connected with the tunnel effect suppression processing unit, and a coordinate output end of which is connected with a terrain deformation rate calculation unit through a data link; The tunnel effect suppression processing unit is built in a multi-beam signal processing board card, an original signal input end of which is connected with a ship-mounted multi-beam transducer array, and a suppressed signal output end of which is connected with the dynamic space homing processing unit through an inter-board interface; The terrain deformation rate calculation unit is deployed in a data processing server, an input end of which receives an elevation coordinate output by the dynamic space homing processing unit, and a change rate output end of which is connected with a monitoring interface of an engineering safety early warning unit through a network; The engineering safety early warning unit is integrated in a monitoring platform, a terrain deformation rate input end of which is connected with the terrain deformation rate calculation unit, and a warning signal output end of which is connected with a corrected terrain output unit through an alarm bus; The corrected terrain output unit is deployed in a graphic workstation, a terrain data input end of which receives a three-dimensional coordinate output by the dynamic space homing processing unit, a warning state input end of which is connected with the engineering safety early warning unit, and an output end of which is connected with a display terminal to generate a three-dimensional terrain model.

Images