1. A ship traveling wave rapid automatic identification method based on machine learning is characterized by comprising the following steps:

step 1: acquiring spectrum data to be identified, and inputting the spectrum data into a ship traveling wave identification model;

step 2: the ship traveling wave identification model identifies whether the wave spectrum data needing to be identified is ship traveling waves;

and step 3: updating the identified spectrum data to a ship traveling wave identification model so as to continuously learn and update the identification capability of the ship traveling wave identification model;

and 4, step 4: repeating the steps 1-3.

2. The machine learning-based ship wave rapid automatic identification method according to claim 1, characterized in that the ship wave identification model is established by:

acquiring ship-shaped wave water surface fluctuation data, converting the data into spectrum data, identifying a ship traveling wave process by utilizing ship traveling spectrum characteristics, and respectively marking ship traveling waves and non-ship traveling waves as model training samples;

and training the multilayer perceptron model by using the marked training samples, and before training the samples, solidifying the model after the training is finished by performing regularization transformation to obtain a ship traveling wave identification model.

3. The machine learning-based ship wave rapid automatic identification method according to claim 2, wherein the multi-layer perceptron model comprises 2 hidden layers, the first layer being 5 neurons.

4. The method of claim 2, wherein the acquiring of the water wave surface fluctuation data of the ship shape wave and the transforming the data into the spectrum data comprises:

the original data is wave surface pressure change data acquired by a pressure sensor, the sampling frequency is 2Hz, and the wave surface pressure change data is converted into water surface fluctuation time sequence data through the pressure and water depth change relation;

and (3) carrying out segmentation processing on the water surface fluctuation time sequence by taking 20 minutes as a time window, and converting the water surface fluctuation time sequence into wave spectrum data through short-time Fourier transform.

5. The method for rapidly and automatically identifying traveling waves of a ship based on machine learning of claim 4, wherein the short-time Fourier transform is characterized in that the values of main parameters are Hamming window parameters of 20s, and windows of 15s are overlapped to obtain spectrum data with the resolution of 5s x 0.05 Hz.

6. The method for fast and automatically identifying traveling wave of ship based on machine learning as claimed in claim 4, wherein the relationship between pressure and water depth is H ═ P/ρ g, H is water depth, P is measured pressure value of the water depth, and ρ and g are pressure and gravitational acceleration of water, respectively.

7. The utility model provides a quick automatic identification equipment of ship travelling wave based on machine learning which characterized in that includes:

the data acquisition module is used for acquiring the spectrum data to be identified and inputting the spectrum data into the ship traveling wave identification model;

the identification module is used for storing the ship traveling wave identification model so as to identify whether the wave spectrum data needing to be identified is the ship traveling wave or not through the ship traveling wave identification model;

and the updating module is used for updating the identified spectrum data to the ship traveling wave identification model so as to continuously learn and update the identification capability of the ship traveling wave identification model.

8. The apparatus according to claim 7, wherein the ship traveling wave identification model is built by:

acquiring ship-shaped wave water surface fluctuation data, converting the data into spectrum data, identifying a ship traveling wave process by utilizing ship traveling spectrum characteristics, and respectively marking ship traveling waves and non-ship traveling waves as model training samples;

training the multilayer sensor model by using the marked training sample, and before training the sample, solidifying the model after the training is finished by performing regularization transformation to obtain a ship traveling wave identification model;

the multi-layer perceptron model includes 2 hidden layers, a first layer of 5 neurons.

9. The apparatus for fast and automatic identification of traveling waves of a ship based on machine learning of claim 7, wherein the acquiring of the wave level fluctuation data of the ship shape wave and the transformation of the data into the spectrum data comprises:

the original data is wave surface pressure change data acquired by a pressure sensor, the sampling frequency is 2Hz, and the wave surface pressure change data is converted into water surface fluctuation time sequence data through the pressure and water depth change relation;

the water surface fluctuation time sequence is processed in a segmented mode by taking 20 minutes as a time window, and is converted into wave spectrum data through short-time Fourier transform;

the short-time Fourier transform is characterized in that the value of the main parameters is that the Hamming window parameters are 20s, and 15s windows are overlapped to obtain the spectrum data with the resolution of 5s multiplied by 0.05 Hz.

10. The apparatus for fast and automatically identifying traveling wave of ship based on machine learning according to claim 9, wherein the relationship between pressure and water depth is H ═ P/pg, H is water depth, P is measured pressure value of the water depth, and P and g are pressure and gravitational acceleration of water, respectively.

Background

At present, ship-shaped wave research is still in an initial stage, the ship-shaped wave characteristics generated by different sizes and draught and water depths are different, and how to separate the ship-shaped wave characteristics from the wind wave background and identify the ship-shaped wave characteristics is a current difficulty. As shown in fig. 1, research shows that the ship-shaped wave presents a Kelvin ship traveling wave structure, and is mainly divided into a transverse wave (transverse wave) and a discrete wave (divergent wave). The edge of the diverging wave makes an angle of about 19 degrees 82 minutes with the course direction.

It has been found that the boat-shaped spectrum formed by measuring passing boats at fixed stations has some significant features, including spectral structures corresponding to transverse and discrete waves, and spectral structures corresponding to non-linear waves caused by some boats (see fig. 2). The traveling wave of the ship can be clearly distinguished from the wind wave background by naked eyes through the characteristics.

The existing ship Automatic Identification methods are high in cost, and the traditional ship Identification method is basically realized by focusing on an optical image Identification technology and installing an Automatic Identification System (AIS) for short. The image recognition technology mainly comprises the recognition technology based on optical imaging and remote sensing pictures, the imaging cost of the image recognition technology is high no matter the image recognition technology is optical imaging or remote sensing pictures, and the recognition success rate is less than 94% (Liu, et al, 2021). Besides the high cost, the AIS system is an active identification mechanism, the trail of the AIS system cannot be recorded under the condition that the AIS system is closed, and the AIS system provides opportunities for subjective escape detection behaviors.

Disclosure of Invention

In order to solve at least one technical problem in the background art, embodiments of the present invention provide a method and an apparatus for fast and automatically identifying a traveling wave of a ship based on machine learning.

In order to achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, an embodiment of the present invention provides a method for quickly and automatically identifying a ship traveling wave based on machine learning, including:

step 1: acquiring spectrum data to be identified, and inputting the spectrum data into a ship traveling wave identification model;

step 2: the ship traveling wave identification model identifies whether the wave spectrum data needing to be identified is ship traveling waves;

and step 3: updating the identified spectrum data to a ship traveling wave identification model so as to continuously learn and update the identification capability of the ship traveling wave identification model;

and 4, step 4: repeating the steps 1-3.

Further, the ship traveling wave identification model is established in the following way:

acquiring ship-shaped wave water surface fluctuation data, converting the data into spectrum data, identifying a ship traveling wave process by utilizing ship traveling spectrum characteristics, and respectively marking ship traveling waves and non-ship traveling waves as model training samples;

and training the multilayer perceptron model by using the marked training samples, and before training the samples, solidifying the model after the training is finished by performing regularization transformation to obtain a ship traveling wave identification model.

Further, the multi-layered perceptron model includes 2 hidden layers, the first layer being 5 neurons.

Further, the acquiring the ship-shaped wave water surface fluctuation data and transforming the data into the spectrum data comprises:

the original data is wave surface pressure change data acquired by a pressure sensor, the sampling frequency is 2Hz, and the wave surface pressure change data is converted into water surface fluctuation time sequence data through the pressure and water depth change relation;

and (3) carrying out segmentation processing on the water surface fluctuation time sequence by taking 20 minutes as a time window, and converting the water surface fluctuation time sequence into wave spectrum data through short-time Fourier transform.

Further, the short-time Fourier transform is carried out by taking the Hamming window parameter as a main parameter and superposing the Hamming window parameter with 15s windows to obtain the spectrum data with the resolution of 5s multiplied by 0.05 Hz.

Further, the relation between the pressure and the water depth is H ═ P/ρ g, H is the water depth, P is a pressure value measured by the water depth, and ρ and g are the pressure and the gravitational acceleration of the water, respectively.

In a second aspect, an embodiment of the present invention provides a device for quickly and automatically identifying a ship traveling wave based on machine learning, including:

the data acquisition module is used for acquiring the spectrum data to be identified and inputting the spectrum data into the ship traveling wave identification model;

the identification module is used for storing the ship traveling wave identification model so as to identify whether the wave spectrum data needing to be identified is the ship traveling wave or not through the ship traveling wave identification model;

and the updating module is used for updating the identified spectrum data to the ship traveling wave identification model so as to continuously learn and update the identification capability of the ship traveling wave identification model.

Further, the ship traveling wave identification model is established in the following way:

acquiring ship-shaped wave water surface fluctuation data, converting the data into spectrum data, identifying a ship traveling wave process by utilizing ship traveling spectrum characteristics, and respectively marking ship traveling waves and non-ship traveling waves as model training samples;

training the multilayer sensor model by using the marked training sample, and before training the sample, solidifying the model after the training is finished by performing regularization transformation to obtain a ship traveling wave identification model;

the multi-layer perceptron model includes 2 hidden layers, a first layer of 5 neurons.

Further, the acquiring the ship-shaped wave water surface fluctuation data and transforming the data into the spectrum data comprises:

the original data is wave surface pressure change data acquired by a pressure sensor, the sampling frequency is 2Hz, and the wave surface pressure change data is converted into water surface fluctuation time sequence data through the pressure and water depth change relation;

the water surface fluctuation time sequence is processed in a segmented mode by taking 20 minutes as a time window, and is converted into wave spectrum data through short-time Fourier transform;

the short-time Fourier transform is characterized in that the value of the main parameters is that the Hamming window parameters are 20s, and 15s windows are overlapped to obtain the spectrum data with the resolution of 5s multiplied by 0.05 Hz.

Further, the relation between the pressure and the water depth is H ═ P/ρ g, H is the water depth, P is a pressure value measured by the water depth, and ρ and g are the pressure and the gravitational acceleration of the water, respectively.

The invention has the beneficial effects that:

according to the invention, machine supervision learning is utilized, time sequence data of water surface fluctuation caused by ship traveling waves are collected at a fixed point through a pressure type or acoustic wave surface measuring instrument, a ship traveling wave recognition model is obtained through a large number of sample training, and passing ships can be accurately recognized. The training samples are diversified in acquisition, and the model can identify ship traveling waves in different types, different ship motion states and different storm backgrounds.

Drawings

FIG. 1 is a view of a Kelvin ship wave structure; in the figure, a black solid line represents a crest line of a discrete wave and a transverse wave system. The dashed line represents the ship-shaped wave edge;

FIG. 2 is a graph of traveling wave energy analysis;

FIG. 3 is a schematic diagram of a single hidden layer multi-layer perceptron network;

fig. 4 is a flowchart illustrating main steps of a method for quickly and automatically identifying a traveling wave of a ship based on machine learning according to this embodiment;

FIG. 5 is a graph comparing MLP and SVM learning curves;

fig. 6 is a schematic diagram of a method for quickly and automatically identifying a traveling wave of a ship based on machine learning according to this embodiment;

FIG. 7 is an exemplary graph of the randomly shuffled samples in test 3;

FIG. 8 is an exemplary graph of the randomly shuffled samples in test 4;

FIG. 9 is an exemplary graph of water surface fluctuation spectrum data after fast Fourier transform;

fig. 10 is a schematic composition diagram of the device for quickly and automatically identifying a traveling wave of a ship based on machine learning according to this embodiment.

Detailed Description

The invention will be further described with reference to the accompanying drawings and the detailed description below:

machine learning develops rapidly, and through the supervised learning of a large amount of data, the machine learning method can learn the characteristics of a certain specific object, can independently identify the object after learning, and is widely applied to the scenes of automatic driving of automobiles, face identification and the like. Machine learning training models according to whether or not labeled samples need to be input can be divided into two categories: supervised learning and unsupervised learning. The supervised learning approach used in embodiments of the present invention has developed a number of models at present: linear models, support vector machines, decision tree models, multi-level perceptron (MLP) models, and the like. The multi-layered perceptron model is developed based on the human brain neural pattern (Kamranzad et al, 2011), which is an artificial neural network of forward structure that maps a set of input vectors to a set of output vectors. As shown in fig. 3, the MLP can be viewed as a directed graph, which is composed of a plurality of node layers, each layer being fully connected to the next layer. Each node, except the input nodes, is a neuron (or processing unit) with a nonlinear activation function. A supervised learning approach called back-propagation algorithm is often used to train MLPs. The multilayer perceptron follows the principle of the human nervous system, learns and makes data predictions. It first learns, then uses weights to store data, and uses algorithms to adjust the weights and reduce the bias in the training process, i.e. the error between the actual and predicted values. The main advantage is its ability to quickly solve complex problems. The basic structure of multilayer perception consists of three layers: the products of the first input layer, the intermediate hidden layer and the final output layer, the input elements and the weights are fed to summing nodes with neuron bias, the main advantage being their ability to quickly solve complex problems. It can learn non-linear function samples to identify transactions with n feature vectors.

Example 1:

referring to fig. 4, the method for quickly and automatically identifying traveling waves of a ship based on machine learning provided by this embodiment mainly includes the following steps:

step 1: acquiring spectrum data to be identified, and inputting the spectrum data into a ship traveling wave identification model;

step 2: the ship traveling wave identification model identifies whether the wave spectrum data needing to be identified is ship traveling waves;

and step 3: updating the identified spectrum data to a ship traveling wave identification model so as to continuously learn and update the identification capability of the ship traveling wave identification model;

and 4, step 4: repeating the steps 1-3.

Specifically, the ship traveling wave identification model is established in the following way:

1 wave spectrum data acquisition and analysis

Collecting wave surface data, obtaining ship travelling wave spectrum data through short-time Fourier transform (referring to a spectral function in matlab), manually identifying a ship travelling wave process by utilizing the characteristics of the ship travelling wave spectrum, and respectively marking the ship travelling wave and the non-ship travelling wave to be used as model training samples.

In order to identify clearly, the sampling frequency of the water surface fluctuation data needs to reach 2 Hz; the time and frequency resolution of the water surface fluctuation spectrum conversion is 5s multiplied by 0.05Hz, so that the identification accuracy is ensured to be more than 92.5 percent. The training and identification data should use the same observation frequency and spectrum conversion parameters.

2 training machine learning model

And training a multilayer perceptron (MLP) model by using the marked samples, and solidifying the model after training before and after the training of the samples so as to obtain a ship traveling wave identification model. The MLP model used for the ship-shaped wave automatic identification is a 2-layer hidden layer, the first layer is provided with five neuron nodes, the second layer is provided with 2 neuron nodes, the layering number and the neuron number are subjected to trial calculation to obtain a proper combination, and overfitting is avoided. And training by inputting the recognized ship shape spectrum data to obtain a curing model capable of automatically recognizing the ship traveling wave. As shown in FIG. 5, through cross validation, the average precision of the MLP model used for the automatic identification of the ship-shaped wave can reach 95.42%, and the precision is basically stable when the number of retraining samples is about 750.

Specifically, the acquiring the ship-shaped wave water surface fluctuation data and converting the data into the spectrum data includes:

the original data is wave surface pressure change data acquired by a pressure sensor, the sampling frequency is 2Hz, and the wave surface pressure change data is converted into water surface fluctuation time sequence data through the pressure and water depth change relation; the pressure and water depth change relationship is H ═ P/rho g, H is the water depth, P is the pressure value measured by the water depth, and rho and g are the pressure and the gravity acceleration of the water respectively.

And (2) carrying out segmentation processing on the water surface fluctuation time sequence by taking 20 minutes as a time window (segmented observation data by taking 20 minutes as the time window can effectively ensure that the ship travelling wave is in the intercepted time period), and converting the ship travelling wave into wave spectrum data through short-time Fourier transform. The short-time Fourier transform has the main parameters as follows: the Hamming window parameter is 20s, and the spectral data with the resolution of 5s multiplied by 0.05Hz can be obtained by the superposition of 15s windows. Thus, the spectrum data can be accurately and effectively acquired.

A large number of fluctuation processes are common storm background processes, wave heights are small, and in order to avoid repeated training of a large number of fluctuation processes of the same type, the fluctuation process with the maximum wave height not exceeding 0.25 m is eliminated.

Thus, the ship traveling wave recognition model established in fig. 6 can accurately and efficiently recognize the ship traveling wave through the above steps.

The sensitivity analysis of the ship traveling wave recognition model on the spectrum is performed by combining 4 groups of test experiments as follows:

a conclusion

A total of 4 sets of test experiments are carried out, and test1 and test2 verify the correctness of the identification model to different resolution spectrums by controlling the time and frequency resolution of the spectrums; the test3 and the test4 check the recognition accuracy of the model by self-making the spectrum on the basis of the original spectrum;

the basic conclusion is that:

1, from test1-2, the model is not sensitive to resolution, and the recognition accuracy is between 0.902 and 0.925 from resolution 10 × 201 to 191 × 201.

2 from test3-4, it can be seen that the error rates of the two homemade spectra are 11.96% and 17.06%, respectively, which are slightly larger than the result of test 1-2.

Two test procedures

It has been concluded previously that the multi-layer perceptron Model (MLP) approach identifies short-time fourier transform spectroscopy (Spec _ STFT) data with the highest accuracy, so sensitivity analysis primarily considers the combination of MLP and Spec _ STFT.

The short-time Fourier transform controls the resolution of Spec _ STFT time and frequency by a window function (window), the number of samples (Noverlap) that overlap between segments, and the number of points (Nfft) at which the discrete Fourier transform is computed. The settings between the three parameters influence each other, and for the discussion of sensitivity analysis of spectral resolution, sensitivity tests were designed by changing only the window length, novelap-10 or novelap-window/2, Nfft-window.

Cross validation final recognition rate

Self-made spectrum data test:

test3

the sample preparation method comprises the following steps: using the window 300 calculation in test, the spectral resolution is t201 f151, the time-wise values for each row are randomly scrambled, and the spectral cloud is changed from the middle to the bottom sub-graph in the graph, as shown in fig. 7. The new pseudo spectrum was identified using a model trained with samples in test1, a total of 2726 samples, 326 spectra that were misidentified as ship waves, an error rate of 326/2726-11.96%,

test4

the sample preparation method comprises the following steps: using the window 300 in test, the resolution of the original spectrum is t201 f 151. The lower half is divided into three parts, which are respectively marked as a1, a2 and a3 from left to right, and then rearranged according to the sequence of a3, a1 and a2, and finally the matrix is upside down, as shown in fig. 8.

The new pseudo spectrum is identified by the model trained with samples in test1, a total of 2726 samples, 465 samples being misidentified as the spectrum of the ship's wave, with an error rate of 17.06%.

Therefore, the identification accuracy of the ship traveling wave identification model established by the embodiment is high

The method provided by the embodiment can be applied to two different application scenarios: 1, real-time wave spectrum identification; 2 wave spectrum data. Both scenarios are identical using spectral recognition techniques, only the front-end data processing approach is involved.

A real-time wave observation system is installed in a ship identification area, pressure type wave monitoring is carried out, and the sampling frequency is at least 2 Hz. The wave collection system can be 500-1000m away from the main channel (the farther away from the main channel, the less probability that the smaller ship traveling wave generated by the small ship on the main channel is accurately identified). By receiving wave surface pressure information, the wave surface pressure information is segmented according to a fixed time window and converted into continuous wave spectrum data.

The ship traveling wave data collected at the pearl estuary is used as an example sample for analysis in the test.

Step 1: training sample preparation

1. The original data is wave surface pressure change data acquired by a pressure sensor, the sampling frequency is 2Hz, and the wave surface pressure change data is converted into water surface fluctuation time sequence data through a pressure and water depth change relation (H is P/rho g, H is water depth, P is a pressure value measured by the water depth, and rho and g are the pressure and the gravity acceleration of water respectively).

2. The water surface fluctuation time sequence is processed in a segmented mode by taking 20 minutes as a time window (statistics shows that the process of observing the ship traveling wave at a fixed point is generally far less than 20 minutes, so segmented observation data by taking 20 minutes as the time window can effectively guarantee that the ship traveling wave is in the intercepted time period), and the ship traveling wave is converted into wave spectrum data through short-time Fourier transform. The short-time Fourier transform has the main parameters as follows: the hamming window parameters are 20s, and the superposition of 15s windows can obtain spectral data with resolution of 5s × 0.05Hz (fig. 9 is an example of the converted boat form into a spectrum).

A large number of fluctuation processes are common storm background processes, wave heights are small, and in order to avoid repeated training of a large number of fluctuation processes of the same type, the fluctuation process with the maximum wave height not exceeding 0.25 m is eliminated.

3. And (3) artificially identifying and marking the ship traveling wave and non-ship traveling wave spectrum processes, wherein a sample containing the ship traveling wave process is marked as 1, and a sample not containing the ship traveling wave process is marked as 0.

Step 2: machine learning model training

By comparison, a Multi-layer Perceptron (Multi-layer Perceptron) model is best suited to identify ship travelling waves. The multilayer perceptron model adopted in the test has 2 hidden layers (5 neurons in the first layer and 2 neurons in the second layer), and the average precision can reach 95.42% through cross validation. The accuracy is already substantially stable when the number of retraining samples is around 750. After training, the model is cured and stored.

And step 3: ship shape wave identification process, accumulated data continuously learning and updating model identification ability

And inputting the process of the traveling wave of the identified ship and identifying the traveling wave of the ship. And (3) after the recognition result is marked, combining the recognition result with the sample in the step (1) to form a new learning sample, continuously training the model, and improving the model recognition precision.

In conclusion, the invention acquires time sequence data of water surface fluctuation caused by ship traveling waves at a fixed point by utilizing machine supervision learning and a pressure type or acoustic type wave surface measuring instrument, obtains a ship traveling wave recognition model by training a large number of samples and can accurately recognize passing ships. The training samples are diversified in acquisition, and the model can identify ship traveling waves in different types, different ship motion states and different storm backgrounds. The invention has the following technical advantages:

1. the realization means is simple, the existing wave acquisition system is commercialized, can be installed in a shore area, and adopts two forms of real-time transmission and periodic data recovery;

2. by collecting more and more ship-shaped spectrum data, the model can be continuously evolved and the identification is more accurate;

3. does not affect the navigation of the ship and adopts an active identification method

4. The identification preparation rate is high, and the accuracy is continuously improved as the samples are increased.

Example 2:

as shown in fig. 10, the present embodiment provides a device for fast and automatically identifying a ship traveling wave based on machine learning, including:

the data acquisition module 101 is used for acquiring spectrum data to be identified and inputting the spectrum data into the ship traveling wave identification model;

the identification module 102 is used for storing a ship traveling wave identification model so as to identify whether the spectrum data to be identified is ship traveling waves or not through the ship traveling wave identification model;

and the updating module 103 is used for updating the identified spectrum data to the ship traveling wave identification model so as to continuously learn and update the identification capability of the ship traveling wave identification model.

Specifically, the ship traveling wave identification model is established in the following manner:

acquiring ship-shaped wave water surface fluctuation data, converting the data into spectrum data, identifying a ship traveling wave process by utilizing ship traveling spectrum characteristics, and respectively marking ship traveling waves and non-ship traveling waves as model training samples;

training the multilayer sensor model by using the marked training sample, and before training the sample, solidifying the model after the training is finished by performing regularization transformation to obtain a ship traveling wave identification model;

the multi-layer perceptron model includes 2 hidden layers, a first layer of 5 neurons.

The acquiring the ship-shaped wave water surface fluctuation data and transforming the data into the spectrum data comprises:

the original data is wave surface pressure change data acquired by a pressure sensor, the sampling frequency is 2Hz, and the wave surface pressure change data is converted into water surface fluctuation time sequence data through the pressure and water depth change relation;

the water surface fluctuation time sequence is processed in a segmented mode by taking 20 minutes as a time window, and is converted into wave spectrum data through short-time Fourier transform;

the short-time Fourier transform is characterized in that the value of the main parameters is that the Hamming window parameters are 20s, and 15s windows are overlapped to obtain the spectrum data with the resolution of 5s multiplied by 0.05 Hz.

The pressure and water depth change relationship is H ═ P/rho g, H is the water depth, P is the pressure value measured by the water depth, and rho and g are the pressure and the gravity acceleration of water respectively.

Various other modifications and changes may be made by those skilled in the art based on the above-described technical solutions and concepts, and all such modifications and changes should fall within the scope of the claims of the present invention.