Self-adaptive heave compensation method and system suitable for submarine surveying and mapping

Abstract

The invention discloses a self-adaptive heave compensation method and system suitable for submarine surveying and mapping, and the method comprises the steps: obtaining a ship attitude angle, and carrying out the coordinate transformation of acceleration information through the attitude angle, and obtaining vertical acceleration information; calculating a surge period by using fast Fourier transform, performing 4096-point FFT calculation, analyzing an FFT unilateral amplitude spectrum, and obtaining a frequency corresponding to a signal with the maximum amplitude as a main frequency of a rolling angle period; carrying out surge heave calculation by adopting a complementary high-pass filter mode: firstly designing a low-pass filter with time delay, and then obtaining a high-pass filter without time delay through a complementary relationship; determining coefficients of a low-pass filter and a high-pass filter, and carrying out lifting filtering calculation; the IIR high-pass filter is designed based on the low-pass complementation principle, the problem of phase delay of a traditional high-pass filter is solved, meanwhile, the calculation order is reduced, and the real-time performance of heave measurement is guaranteed.

Description

Technical Field

[0001] This invention belongs to the field of wave compensation technology for seabed mapping, and particularly relates to an adaptive heave compensation method and system suitable for seabed mapping. Background Technology

[0002] Wave compensation technology directly determines the accuracy of seabed mapping and is also the core technology for matching fiber optic inertial navigation systems with multiple beams for seabed mapping.

[0003] Traditional heave measurement primarily utilizes the accelerometer output of the inertial navigation system (INS) in the heave direction, solving for heave motion information through quadratic integration. However, due to the cumulative error of the INS and the divergence characteristics of the height channel, it is unsuitable for accurately measuring long-period displacement changes. Therefore, a digital high-pass filter is needed to eliminate the influence of long-period motion and accelerometer bias measurement errors based on the vertical quadratic integration calculation. Since ocean wave periods are generally 4–20 seconds, which is a low-frequency input, the high-pass filter's pass frequency needs to be much lower than the ocean wave frequency. Simultaneously, ensuring the real-time performance and accuracy of heave measurement presents a significant challenge to the heave compensation algorithm. Summary of the Invention

[0004] This invention designs an IIR high-pass filter based on the low-pass complementarity principle to eliminate the phase delay problem of traditional high-pass filters while reducing the computational order and ensuring the real-time performance of heave measurements. By performing a real-time fast Fourier transform on the attitude angle of the inertial navigation system to obtain the wave frequency and calculate the wave period, it serves as the cutoff frequency input reference for the complementary high-pass filter, thereby realizing an adaptive complementary high-pass filter under different sea conditions.

[0005] The present invention adopts the following technical solution:

[0006] Adaptive heave compensation methods applicable to seabed mapping include the following methods:

[0007] Obtain the ship's attitude angles, and use the attitude angles to perform coordinate transformation on the acceleration information to obtain the vertical acceleration information;

[0008] The surge period was calculated using Fast Fourier Transform (FFT). A 4096-point FFT was performed, and the single-sided amplitude spectrum of the FFT was analyzed to obtain the frequency corresponding to the signal with the maximum amplitude, which was taken as the main frequency of the roll angle period.

[0009] A complementary high-pass filter mode is used for surge heave calculation: first, a low-pass filter with delay is designed, and then a high-pass filter without delay is obtained through the complementary relationship.

[0010] Determine the coefficients of the low-pass and high-pass filters, and perform rise and fall filtering calculations: Integrate the vertical acceleration twice to obtain the vertical position, and insert a complementary high-pass filter in between to filter out low-frequency components.

[0011] Furthermore, the hull attitude angles can be obtained from the rotation matrix, the expression of which is shown below:

[0012]

[0013] The attitude angle is calculated from the rotation matrix as follows:

[0014]

[0015] Where θ, γ, and ψ are the pitch angle, roll angle, and heading angle, respectively.

[0016] Furthermore, the surge period is calculated using Fast Fourier Transform (FFT), a 4096-point FFT is performed, and the single-sided amplitude spectrum of the FFT is analyzed to obtain the frequency corresponding to the signal with the maximum amplitude. This frequency is then used as the dominant frequency of the roll angle period.

[0017] The formula for calculating the Discrete Fourier Transform (DFT) is as follows:

[0018]

[0019] Where the frequency index k = 0, 1, 2, ..., N-1, and j is the imaginary unit. The transform kernel function is x[n], the DFT input sequence is N=4096, the number of DFT points is N, and the amplitude at frequency index k is X[k].

[0020] The radix-2 FFT algorithm is used to reduce computational complexity. An N-point Discrete Fourier Transform (DFT) is decomposed into two N / 2 DFTs, recursively layered until a 2-point DFT is reached. After computation, these layers are merged into the entire N-point DFT, reducing the computational complexity from O(N) to O(N). 2 The value is reduced to O(NlogN).

[0021] Furthermore, the method for designing a low-pass filter with a time delay is as follows:

[0022] The system transfer function expression for a third-order low-pass filter is:

[0023] H(z) = (b0 + b1z) -1 +b2z -2 +b3z -3 ) / (1+a1z -1 +a2z -2 +a3z -3 )

[0024] Given the cutoff frequency f c Sampling frequency f s The coefficients of the third-order low-pass IIR filter are calculated as follows:

[0025] Calculate the digital cutoff frequency:

[0026] ω d =2π·(f c / f s )

[0027] Calculate the simulated cutoff frequency:

[0028] ω a =2·tan(ω) d / 2)=2·tan(π·f c / f s )

[0029] Determine the prototype analog Butterworth low-pass filter:

[0030] The poles of the third-order normalized Butterworth low-pass filter are:

[0031] s1=-sin(π / 6)+j·cos(π / 6)=-0.5+j·0.8660

[0032] s2=-sin(π / 2)+j·cos(2)=-1.0+j·0

[0033] s3=-sin(5π / 6)+j·cos(5π / 6)=-0.5-j·0.8660

[0034] Normalized analog low-pass filter transfer function:

[0035] H an (s n )=1 / [(s n -s1)(s n -s2)(s n -s3)]

[0036] Substituting, we get:

[0037]

[0038] Let s n =s / ω a Substituting and simplifying to

[0039]

[0040] Calculate the low-pass filter coefficients:

[0041] The bilinear transformation formula is s = 2·(1-z) -1 ) / (1+z -1 ), substitute H an (s)

[0042]

[0043] Summarized as follows:

[0044]

[0045] in,

[0046] By comparing the transfer function of the filter system, the coefficients of the low-pass filter can be obtained as follows:

[0047] a0 = 1

[0048]

[0049] Furthermore, the method for obtaining a delay-free high-pass filter through complementary relationships is as follows:

[0050] Using the complementarity principle, the transfer function of the complementary filter is obtained as follows:

[0051]

[0052] In summary, the coefficients of the complementary high-pass filter are:

[0053] a0′=1

[0054]

[0055] Furthermore, the method for determining the coefficients of the low-pass filter and high-pass filter, and then performing up-and-down filtering calculations, is as follows:

[0056] The heave filtering calculation process mainly involves integrating the vertical acceleration calculated by the inertial navigation system twice to obtain the vertical position, and then inserting a complementary high-pass filter to filter out low-frequency components. The calculation process is as follows:

[0057] V k =V k-1 +f k Δt

[0058]

[0059] in, h k For the rise and fall velocities, a i ′、b i ' represents the filter coefficients, Δt represents the solution step size, and f k This is the vertical acceleration.

[0060] Furthermore, the vertical acceleration can be calculated from the velocity equation:

[0061]

[0062] in, The velocity increment in the navigation frame is the acceleration in the navigation frame; the vertical acceleration is the third value of the vector. g n This represents the local gravitational acceleration in the navigation system. Represents the input of the accelerometer; The rotation matrix from the carrier system to the navigation system; The rotation of the navigation system is caused by the Earth's rotation. The rotation of the inertial navigation system as it moves near the Earth's surface is caused by the curvature of the Earth's surface.

[0063] An adaptive heave compensation system suitable for seabed mapping includes the following:

[0064] The vertical acceleration information acquisition module is used to acquire the ship's attitude angles and perform coordinate transformation on the acceleration information through the attitude angles to obtain the vertical acceleration information.

[0065] The main frequency acquisition module of the roll angle period is used to calculate the surge period using fast Fourier transform, perform 4096-point FFT calculation, analyze the FFT single-sided amplitude spectrum, and obtain the frequency corresponding to the signal with the maximum amplitude, which is used as the main frequency of the roll angle period.

[0066] The filter acquisition module is used to acquire complementary high-pass filter patterns: first, a low-pass filter with delay is designed, and then a high-pass filter without delay is obtained through the complementary relationship.

[0067] The rise and fall filter calculation module is used to determine the coefficients of the low-pass filter and the high-pass filter, and to perform rise and fall filter calculations: the vertical acceleration is integrated twice to obtain the vertical position, and a complementary high-pass filter is inserted in between to filter out low-frequency components.

[0068] A non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the adaptive heave compensation method for seabed mapping as described above.

[0069] An electronic device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the program, implements the adaptive heave compensation method for seabed mapping as described above.

[0070] The beneficial technical effects of this invention are as follows:

[0071] This invention overcomes the limitations of fixed-parameter filtering in traditional heave measurement devices by establishing a dynamic parameter correction mechanism based on real-time estimation of wave periods. It acquires wave surface motion data in real time through embedded sensors, and combines Fast Fourier Transform (FFT) and peak detection algorithms to achieve online identification of the main wave period. Based on this, the heave filtering parameters are dynamically adjusted, enabling the system to adapt to sea conditions. Compared to existing technologies, this invention solves the problem of measurement inaccuracies caused by abrupt changes in wave spectrum under different sea conditions. Attached Figure Description

[0072] Figure 1 This is a diagram showing the low dynamic heave calculation results provided in an embodiment of the present invention;

[0073] Figure 2 This is a diagram showing the high dynamic heave calculation results provided in an embodiment of the present invention. Detailed Implementation

[0074] The following, in conjunction with the accompanying drawings, provides a clearer and more complete description of the power supply capacity adjustment and optimization method and system for a multi-source long-distance traction power supply system provided by the present invention:

[0075] Example 1

[0076] The adaptive heave compensation method for seabed mapping provided by this invention includes the following methods:

[0077] Obtain the ship's attitude angles, and use the attitude angles to perform coordinate transformation on the acceleration information to obtain the vertical acceleration information;

[0078] The surge period was calculated using Fast Fourier Transform (FFT). A 4096-point FFT was performed, and the single-sided amplitude spectrum of the FFT was analyzed to obtain the frequency corresponding to the signal with the maximum amplitude, which is the main frequency of the roll angle period.

[0079] A complementary high-pass filter mode is used for surge heave calculation: first, a low-pass filter with delay is designed, and then a high-pass filter without delay is obtained through the complementary relationship.

[0080] Determine the coefficients of the low-pass and high-pass filters, and perform rise and fall filtering calculations: Integrate the vertical acceleration twice to obtain the vertical position, and insert a complementary high-pass filter in between to filter out low-frequency components.

[0081] In summary, this invention achieves an adaptive complementary high-pass filter under different sea conditions by performing real-time fast Fourier transform on the attitude angle of the inertial navigation system to obtain the wave frequency and calculate the wave period, which serves as the cutoff frequency input reference for the complementary high-pass filter.

[0082] Specifically,

[0083] The hull attitude angles can be obtained from the rotation matrix, the expression of which is shown below:

[0084]

[0085] The attitude angle is calculated from the rotation matrix as follows:

[0086]

[0087] Wherein, θ, γ, and ψ are the pitch angle, roll angle, and heading angle, respectively;

[0088] It should be noted that the rotation matrix is ​​obtained by solving the following differential equation:

[0089]

[0090] in, The rotation matrix from the carrier system to the navigation system. For the gyroscope input, The rotation of the navigation system is caused by the Earth's rotation. The rotation of the inertial navigation system caused by the curvature of the Earth's surface when the system moves near the Earth's surface can be calculated using the following formula:

[0091]

[0092] Where, ν E ν N h, L represent the ship's eastward speed, northward speed, altitude, and latitude, respectively; R M R N f and r represent the radii of the Earth's meridian and circumference, respectively, and the oblateness of the meridian. e R p The Earth's major and minor axes.

[0093] To reduce computational complexity, the differential equations of the rotation matrix are solved using the quaternion method:

[0094]

[0095] Where, p * (h) represents the navigation coordinate system transformation within the attitude update cycle, and q(h) represents the attitude angle transformation caused by the gyroscope sensitivity value, respectively derived from... and The calculation yielded:

[0096]

[0097]

[0098] Where, Φ q The rotation vector caused by the carrier's rotation is determined by the gyroscope's sensitivity value. We obtain Φ q For Φ qThe model, Φ is the sensitivity value of the gyroscope. p Φ is the rotation vector caused by the rotation of the navigation coordinate system. p For Φ p The model, h represents the rotation of the navigation coordinate system relative to the inertial coordinate system; h is the solution step size.

[0099] The conversion relationship between quaternions and rotation matrices is as follows:

[0100] Q k =[q0 q1 q2 q3]

[0101]

[0102] Vertical acceleration can be calculated from the velocity equation.

[0103]

[0104] in, The velocity increment in the navigation frame is the acceleration in the navigation frame; the vertical acceleration is the third value of the vector. g n This represents the local gravitational acceleration in the navigation system. This represents the input to the accelerometer.

[0105] The surge period is calculated using Fast Fourier Transform (FFT). The surge period is generally 2 to 40 seconds. Considering the actual computing power of embedded computers, the roll angle sampling period is set to 10 Hz. A 4096-point Fast Fourier Transform (FFT) calculation is performed. The single-sided amplitude spectrum of the FFT is analyzed to obtain the frequency corresponding to the signal with the maximum amplitude, which is the main frequency of the roll angle period.

[0106] The formula for calculating DFT is:

[0107]

[0108] Where k = 0, 1, 2, ..., N-1 (frequency index), and j is the imaginary unit (ji). 2 =-1), The transform kernel function is x[n], which is the DFT input sequence, i.e. the roll angle sample value, N = 4096, which is the number of DFT points, and X[k] is the amplitude at the frequency index k.

[0109] The Cooley-Tukey algorithm is used to reduce computational complexity. The core idea is to decompose an N-point DFT (Discrete Fourier Transform) into two N / 2 DFTs, recursively layering them down to the 2-point DFT, and then merging them layer by layer to form the entire N-point DFT. This reduces the computational complexity from O(N) to O(2). 2The value is reduced to O(NlogN).

[0110] The calculation principle is as follows:

[0111] 1. Decompose the original input sequence x[n] into two subsequences x[2m] and x[2m+1] according to parity, where

[0112] m = 0, 1, 2, ..., N / 2-1;

[0113] 2. Calculate the DFT of the two subsequences of length N / 2 respectively, and denote them as:

[0114]

[0115] in, is the rotation factor.

[0116] 3. Using W N G[k] and H[k] are combined to form the final X[k]:

[0117]

[0118] Where k = 0, 1, 2, ..., N / 2-1.

[0119] After obtaining X[k], it can be sorted by size. Find the frequency point corresponding to the maximum value when k≠0 to obtain the hull's rolling frequency. In order to ensure that the roll angle is offset and noise does not affect the rolling frequency, the x[n] sequence needs to be low-pass filtered first.

[0120] Next, the parameters of the rise / fall filter will be calculated:

[0121] The essence of swell heave calculation is to obtain the vertical position by integrating the ship's vertical acceleration twice. The vertical acceleration is given by the inertial navigation algorithm. Since the low-frequency components of the vertical acceleration cause the integration result to diverge over time, a high-pass filter is needed to filter out the low-frequency part and retain the high-frequency part. Traditional digital high-pass filters are divided into two types: FIR (Finite Impulse Response) and IIR (Infinite Impulse Response). FIR filters have the advantage of phase stability, but require a large order and have a large computational load, making them unsuitable for embedded environments. IIR filters require a lower order and are suitable for embedded environments, but have a large phase lag. Considering both embedded applications and filtering delay, a complementary high-pass filter is adopted. That is, a low-pass filter with delay is designed first, and then a high-pass filter without delay is obtained through complementarity.

[0122] The system transfer function expression for a third-order low-pass filter is:

[0123] H(z) = (b0 + b1z) -1 +b2z -2+b3z -3 ) / (1+a1z -1 +a2z -2 +a3z -3 )

[0124] Given the cutoff frequency f c Sampling frequency f s The coefficients of the third-order low-pass IIR filter are calculated as follows:

[0125] Calculate the digital cutoff frequency

[0126] ω d =2π·(f c / f s )

[0127] Calculate the simulated cutoff frequency

[0128] ω a =2·tan(ω) d / 2)=2·tan(π·f c / f s )

[0129] Determine the prototype analog Butterworth low-pass filter:

[0130] The poles of the third-order normalized Butterworth low-pass filter are:

[0131] s1=-sin(π / 6)+j·cos(π / 6)=-0.5+j·0.8660

[0132] s2=-sin(π / 2)+j·cos(2)=-1.0+j·0

[0133] s3=-sin(5π / 6)+j·cos(5π / 6)=-0.5-j·0.8660

[0134] Normalized analog low-pass filter transfer function:

[0135] H an (s n )=1 / [(s n -s1)(s n -s2)(s n -s3)]

[0136] Substituting, we get:

[0137]

[0138] Let s n =s / ω a Substituting and simplifying to

[0139]

[0140] Calculate the low-pass filter coefficients:

[0141] The bilinear transformation formula is s = 2·(1-z) -1 ) / (1+z -1 ), substitute H an (s)

[0142]

[0143] Summarized as follows:

[0144]

[0145] in,

[0146] By comparing the transfer function of the filter system, the coefficients of the low-pass filter can be obtained as follows:

[0147] a0 = 1

[0148]

[0149] Find the coefficients of the complementary high-pass filter:

[0150] Using the complementarity principle, the transfer function of the complementary filter is obtained as follows:

[0151]

[0152] In summary, the coefficients of the complementary high-pass filter are:

[0153] a0′=1

[0154]

[0155] Heave-dip filtering calculation:

[0156] The heave filtering calculation process mainly involves integrating the vertical acceleration calculated by the inertial navigation system twice to obtain the vertical position, and then inserting a complementary high-pass filter to filter out low-frequency components. The calculation process is as follows:

[0157] V k =V k-1 +f k Δt

[0158]

[0159] in, h k For the rise and fall velocities, a i ′、b i ' represents the filter coefficients, Δt represents the solution step size, and fk This is the vertical acceleration.

[0160] As an example, in this embodiment, a high-order FIR filter (phase stable, waveform undistorted, can be considered a standard value), a fixed-parameter complementary IIR filter (filter parameters fixed), a regular IIR filter (IIR high-pass filter), and the adaptive complementary IIR filter of this invention are used for rise and fall calculation. The low dynamic rise and fall calculation results are as follows: Figure 1 As shown, from Figure 1 As can be seen, ordinary IIR filtering has a large phase delay, which is inferior to complementary IIR filtering. Adaptive complementary IIR filtering outperforms fixed-parameter IIR filtering in terms of amplitude. The high dynamic heave calculation results are as follows: Figure 2 As shown, from Figure 2 As can be seen, ordinary IIR filtering has significant waveform distortion and is inferior to complementary IIR filtering. Adaptive complementary IIR filtering is superior to fixed-parameter IIR filtering in terms of waveform distortion.

[0161] Example 2

[0162] The present invention also adopts the following technical solutions:

[0163] An adaptive heave compensation system suitable for seabed mapping includes the following:

[0164] The vertical acceleration information acquisition module is used to acquire the ship's attitude angles and perform coordinate transformation on the acceleration information through the attitude angles to obtain the vertical acceleration information.

[0165] The main frequency acquisition module of the roll angle period is used to calculate the surge period using fast Fourier transform, perform 4096-point FFT calculation, analyze the FFT single-sided amplitude spectrum, and obtain the frequency corresponding to the signal with the maximum amplitude, which is used as the main frequency of the roll angle period.

[0166] The filter acquisition module is used to acquire complementary high-pass filter patterns: first, a low-pass filter with delay is designed, and then a high-pass filter without delay is obtained through the complementary relationship.

[0167] The rise and fall filter calculation module is used to determine the coefficients of the low-pass filter and the high-pass filter, and to perform rise and fall filter calculations: the vertical acceleration is integrated twice to obtain the vertical position, and a complementary high-pass filter is inserted in between to filter out low-frequency components.

[0168] A non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the adaptive heave compensation method for seabed mapping as described above.

[0169] Furthermore, the present invention adopts the following technical solution:

[0170] An electronic device includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the adaptive heave compensation method for seabed mapping as described above.

[0171] From the above description of the embodiments, those skilled in the art will clearly understand that the facilities of the present invention can be implemented using software plus necessary general-purpose hardware platforms. Embodiments of the present invention can be implemented using existing processors, or by dedicated processors used for this or other purposes for suitable systems, or by hardwired systems. Embodiments of the present invention also include non-transitory computer-readable storage media, comprising machine-readable media for carrying or having machine-executable instructions or data structures stored thereon; such machine-readable media can be any available medium accessible by a general-purpose or special-purpose computer or other machine with a processor. For example, such machine-readable media can include RAM, ROM, EPROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store the required program code in the form of machine-executable instructions or data structures and is accessible by a general-purpose or special-purpose computer or other machine with a processor. When information is transmitted or provided to a machine via a network or other communication connection (hardwired, or wireless, or a combination of hardwired and wireless), that connection is also considered a machine-readable medium.

[0172] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. An adaptive heave compensation method suitable for seabed mapping, characterized in that, Including the following methods: Obtain the ship's attitude angles, and use the attitude angles to perform coordinate transformation on the acceleration information to obtain the vertical acceleration information; The surge period was calculated using Fast Fourier Transform (FFT). A 4096-point FFT was performed, and the single-sided amplitude spectrum of the FFT was analyzed to obtain the frequency corresponding to the signal with the maximum amplitude, which was taken as the main frequency of the roll angle period. A complementary high-pass filter mode is used for surge heave calculation: first, a low-pass filter with delay is designed, and then a high-pass filter without delay is obtained through the complementary relationship. Determine the coefficients of the low-pass and high-pass filters, and perform rise and fall filtering calculations: Integrate the vertical acceleration twice to obtain the vertical position, and insert a complementary high-pass filter in between to filter out low-frequency components.

2. The adaptive heave compensation method for seabed mapping according to claim 1, characterized in that, The hull attitude angles can be obtained from the rotation matrix, the expression of which is shown below: The attitude angle is calculated from the rotation matrix as follows: Where θ, γ, and ψ are the pitch angle, roll angle, and heading angle, respectively.

3. The adaptive heave compensation method for seabed mapping according to claim 1, characterized in that, The surge period is calculated using Fast Fourier Transform (FFT). A 4096-point FFT is performed, and the single-sided amplitude spectrum of the FFT is analyzed to determine the frequency corresponding to the signal with the maximum amplitude. This frequency is then used as the dominant frequency of the roll angle period. The formula for calculating the Discrete Fourier Transform (DFT) is as follows: Where the frequency index k = 0, 1, 2, ..., N-1, and j is the imaginary unit. The transform kernel function is x[n], the DFT input sequence is N=4096, the number of DFT points is N, and the amplitude at frequency index k is X[k]. The radix-2 FFT algorithm is used to reduce computational complexity. An N-point Discrete Fourier Transform (DFT) is decomposed into two N / 2 DFTs, recursively layered until a 2-point DFT is reached. The DFTs are then merged layer by layer to form the complete N-point DFT, reducing the computational complexity from O(N) to O(N). 2 The value is reduced to O(NlogN).

4. The adaptive heave compensation method for seabed mapping according to claim 1, characterized in that, The method for designing a low-pass filter with a time delay is as follows: The system transfer function expression for a third-order low-pass filter is: H(z)=(b0+b1z -1 +b2z -2 +b3z -3 ) / (1+a1z -1 +a2z -2 +a3z -3 ) Given the cutoff frequency f c Sampling frequency f s The coefficients of the third-order low-pass IIR filter are calculated as follows: Calculate the digital cutoff frequency: ω d =2π·(f c / f s ) Calculate the simulated cutoff frequency: ω a =2·tan(ω d / 2)=2·tan(π·f c / f s ) Determine the prototype analog Butterworth low-pass filter: The poles of the third-order normalized Butterworth low-pass filter are: s1=-sin(π / 6)+j·cos(π / 6)=-0.5+j·0.8660 s2=-sin(π / 2)+j·cos(2)=-1.0+j·0 s3=-sin(5π / 6)+j·cos(5π / 6)=-0.5-j·0.8660 Normalized analog low-pass filter transfer function: H an (s n )=1 / [(s n -s1)(s n -s2)(s n -s3)] Substituting, we get: Let s n =s / ω a Substituting and simplifying to Calculate the low-pass filter coefficients: The bilinear transformation formula is s = 2·(1-z) -1 ) / (1+z -1 ), substitute H an (s) Summarized as follows: in, By comparing the transfer function of the filter system, the coefficients of the low-pass filter can be obtained as follows: a0＝1 5. The adaptive heave compensation method for seabed mapping according to claim 4, characterized in that, The method for obtaining a time-delay-free high-pass filter through complementary relationships is as follows: Using the complementarity principle, the transfer function of the complementary filter is obtained as follows: In summary, the coefficients of the complementary high-pass filter are:

6. The adaptive heave compensation method for seabed mapping according to claim 5, characterized in that, The method for determining the coefficients of the low-pass and high-pass filters and performing up-and-down filtering calculations is as follows: The heave filtering calculation process mainly involves integrating the vertical acceleration calculated by the inertial navigation system twice to obtain the vertical position, and then inserting a complementary high-pass filter to filter out low-frequency components. The calculation process is as follows: V k =V k-1 +f k Δt in, h k For the rise and fall velocities, a i ′、b i ' represents the filter coefficients, Δt represents the solution step size, and f k This is the vertical acceleration.

7. The adaptive heave compensation method for seabed mapping according to claim 2, characterized in that, Vertical acceleration can be calculated from the velocity equation: in, The velocity increment in the navigation frame is the acceleration in the navigation frame; the vertical acceleration is the third value of the vector. g n This represents the local gravitational acceleration in the navigation system. Represents the input of the accelerometer; The rotation matrix from the carrier system to the navigation system; The rotation of the navigation system is caused by the Earth's rotation. The rotation of the inertial navigation system as it moves near the Earth's surface is caused by the curvature of the Earth's surface.

8. An adaptive heave compensation system suitable for seabed mapping, characterized in that, Including the following: The vertical acceleration information acquisition module is used to acquire the ship's attitude angles and perform coordinate transformation on the acceleration information through the attitude angles to obtain the vertical acceleration information. The main frequency acquisition module of the roll angle period is used to calculate the surge period using fast Fourier transform, perform 4096-point FFT calculation, analyze the FFT single-sided amplitude spectrum, and obtain the frequency corresponding to the signal with the maximum amplitude, which is used as the main frequency of the roll angle period. The filter acquisition module is used to acquire complementary high-pass filter patterns: first, a low-pass filter with delay is designed, and then a high-pass filter without delay is obtained through the complementary relationship. The rise and fall filter calculation module is used to determine the coefficients of the low-pass filter and the high-pass filter, and to perform rise and fall filter calculations: the vertical acceleration is integrated twice to obtain the vertical position, and a complementary high-pass filter is inserted in between to filter out low-frequency components.

9. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the computer program implements the adaptive heave compensation method for seabed mapping as described in any one of claims 1 to 7.

10. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the adaptive heave compensation method for seabed mapping as described in any one of claims 1 to 7.

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