Method for positioning mobile node based on underwater acoustic communication network

Abstract

The invention discloses a method for positioning a mobile node based on an underwater acoustic communication network, and the method comprises the following steps: S1, checking whether a subsurface buoy can transmit and receive signals normally, and if the subsurface buoy transmits and receives signals normally, putting the subsurface buoy to a preset underwater position to form an underwater acoustic communication network; s2, the underwater acoustic communication network receives, processes and gathers the frequency modulation signals sent by the mobile nodes to obtain gathered signals; s3, resolving the summarized signal by using a TDOA algorithm to obtain position information of the mobile node, and then sending the position information to a surface ship terminal, so as to solve the problems that the layout and recovery cost of the existing long baseline positioning acoustic array is high; and due to the increase of the acoustic arrays, a long-baseline system is tedious, the operation is complicated, and the method is not suitable for underwater mobile node positioning in a small-range area.

Description

Technical Field

[0001] The present application relates to the technical field of underwater mobile node positioning, and in particular to a method for positioning a mobile node based on an underwater acoustic communication network. Background Art

[0002] Underwater positioning technologies such as long baseline positioning mainly determine the location of the target object by deploying multiple base stations (usually sonar equipment) underwater. These base stations are arranged in known fixed positions, and the distance is calculated by measuring the sound wave propagation time between the target mobile node and the base station, and then the position is inferred. The length of the base array of long baseline positioning is generally in the order of hundreds of meters to thousands of meters. The calibration work of a huge number of acoustic arrays before use is cumbersome, and the cost of array deployment and recovery is also extremely expensive; the increase in acoustic arrays also makes the long baseline system cumbersome and complex to operate, which is not suitable for underwater mobile node positioning in a small area.

[0003] Therefore, a method for positioning a mobile node based on an underwater acoustic communication network is needed to solve the problems raised in the above background technology. Summary of the invention

[0004] The purpose of the present invention is to provide a method for positioning a mobile node based on an underwater acoustic communication network to solve the problems raised in the above background technology.

[0005] In view of this, the present application provides a method for positioning a mobile node based on an underwater acoustic communication network, comprising the following steps: S1. Check whether the submerged buoy can normally send and receive signals. If the submerged buoy can normally send and receive signals, the submerged buoy is placed at a predetermined underwater position to form an underwater acoustic communication network. S2, the underwater acoustic communication network receives the frequency modulation signal sent by the mobile node, processes and summarizes it, and obtains a summary signal; S3. Use the TDOA algorithm to solve the summary signal to obtain the location information of the mobile node, and then send the location information to the surface ship terminal.

[0006] Optionally, the underwater acoustic communication network is composed of four of the aforementioned buoys.

[0007] Optionally, in step S2, the underwater acoustic communication network receives the frequency modulation signal sent by the mobile node, processes and aggregates the signal, and the method steps for obtaining the aggregated signal are: designate one of the four buoys as a primary buoy and the other three as secondary buoys; The three auxiliary submerged buoys and the main submerged buoy all receive the frequency modulation signal, and process the frequency modulation signal to obtain a communication signal; The communication signals of the remaining three auxiliary buoys are then transmitted to the main buoy for aggregation to obtain an aggregated signal.

[0008] Optionally, the communication signals of the remaining three auxiliary submerged buoys are transmitted to the main submerged buoy for aggregation to obtain the aggregated signal by the following method steps: Perform cross-correlation processing on the frequency modulation signals received by the three secondary buoys and the main buoy and the original frequency modulation signal of the signal parameters set by the transmitting end to find the maximum correlation peak, and obtain the propagation time according to the maximum correlation peak; The three auxiliary buoys convert the acquired propagation time data into communication signals within a predetermined frequency band through OFDM modulation technology, and send them to the main buoy through the hydroacoustic channel for aggregation to obtain an aggregated signal.

[0009] Optionally, in step S3, the method steps of using the TDOA algorithm to solve the summary signal to obtain the location information of the mobile node, and then sending the location information to the surface ship terminal are: Using OFDM demodulation technology at the main buoy to demodulate the summary information to obtain delay information; Then, the time delay information is solved by using a TDOA algorithm to obtain the location information of the mobile node; The position information is then sent to the surface ship terminal.

[0010] Optionally, the method steps of cross-correlating the frequency modulation signals received by the three secondary buoys and the main buoy with the original frequency modulation signals of the signal parameters set by the transmitting end to find the maximum correlation peak, and obtaining the propagation time according to the maximum correlation peak are as follows: The generalized cross-correlation method is used to perform Fourier transform on the cross-correlation function to obtain the cross-power spectrum, and the frequency domain relationship between the signals is analyzed. After obtaining the cross-power spectrum, the generalized cross-correlation method uses a specific weighting function for weighted processing, and then the frequency modulation signals received by the three secondary buoys and the main buoy are generalized cross-correlated with the original frequency modulation reference signal sent by the mobile node to find the maximum correlation peak and obtain the signal propagation time; The calculation formula of the generalized cross-correlation method is:

[0011] in, is the cross-spectrum, is the frequency domain weighting function, is a constant, For plural units, For variables, is the signal delay.

[0012] Optionally, in step S1, the method steps for checking whether the latent buoy can normally send and receive signals are: Connect an initial submersible to the UartAssist serial debugging assistant; The initial latent beacon is controlled to send an audio signal by issuing a serial port instruction for audio transmission, and then the audio signal is received by another latent beacon to be tested. If the tested latent buoy receives the audio signal normally and sends back a feedback audio signal to the initial latent buoy, the feedback audio signal is displayed on the UartAssist serial port debugging assistant, proving that both latent buoys are sending and receiving audio signals normally.

[0013] Optionally, in step S1, the placing of the submerged buoy to a predetermined underwater position for underwater acoustic communication networking specifically includes: before starting to place the submerged buoy, the placing position of the submerged buoy needs to be designed in advance according to the position of the mobile node; The four buoys are deployed in a rectangular shape, and the buoys are deployed after the deployment position is located using GPS, and underwater acoustic communication networking is performed.

[0014] It can be seen from the above technical solutions that the embodiments of the present application have the following advantages: The present application provides a method for positioning a mobile node based on an underwater acoustic communication network. Compared with the prior art, the method of the present invention includes the following steps: S1, checking whether a buoy can normally send and receive signals. If the buoy can normally send and receive signals, the buoy is placed at a predetermined underwater position to form an underwater acoustic communication network; S2, the underwater acoustic communication network receives the frequency modulation signal sent by the mobile node, processes and summarizes it, and obtains a summary signal; S3, using the TDOA algorithm to solve the summary signal to obtain the position information of the mobile node, and then sending the position information to a surface ship terminal to facilitate the display of the position information of the mobile node, thereby ensuring that an underwater communication network can be effectively established, and stable communication between various buoy devices can be achieved. The method can accurately record the delay information at the time of reception, add it to the communication signal and send it to the main buoy, and use the time difference positioning (TDOA) algorithm to calculate the accurate position of the mobile node through the delay information provided by each secondary buoy. The operation is simple and suitable for positioning underwater mobile nodes in a small area. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly express the technical solutions of the embodiments of the present application, the drawings required for describing the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0016] Figure 1A diagram showing the steps of the method of the present invention; Figure 2 It is a schematic diagram of the structure of the positioning system of the present invention; Figure 3 It is a schematic diagram of the time delay estimation of the latent marker of the present invention; Figure 4 A comparison diagram of the actual trajectory of a mobile node target and the positioning trajectory and a comparison diagram of the actual value and the estimated value of the mobile node target speed of the present invention; Figure 5 It is a schematic diagram of the TDOA positioning model of the present invention. DETAILED DESCRIPTION

[0017] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application.

[0018] For easier understanding, see Figures 1 to 4 The present invention provides a method for positioning a mobile node based on an underwater acoustic communication network, comprising the following steps: S1. Check whether the submerged buoy can normally send and receive signals. If the submerged buoy can normally send and receive signals, the submerged buoy is placed at a predetermined underwater position to form an underwater acoustic communication network. Specifically, the underwater acoustic communication network is composed of four of the underwater buoys, and the underwater buoy is an underwater acoustic communication machine.

[0019] Furthermore, in step S1, the method steps for checking whether the latent buoy can normally send and receive signals are as follows: S11. Connect an initial submersible to the UartAssist serial port debugging assistant; S12, controlling the initial latent beacon to send an audio signal by issuing a serial port instruction for audio transmission, and then receiving the audio signal through another latent beacon to be tested; S13. If the tested latent buoy receives the audio signal normally and sends back a feedback audio signal to the initial latent buoy, the feedback audio signal is displayed on the UartAssist serial port debugging assistant, proving that both latent buoys are sending and receiving audio signals normally.

[0020] Further, in step S1, the placing of the submerged buoy to a predetermined underwater position for underwater acoustic communication networking specifically includes: before starting to place the submerged buoy, the placing position of the submerged buoy needs to be designed in advance according to the position of the mobile node; The four buoys are deployed in a rectangular shape, and the buoys are deployed after the deployment position is located using GPS, and underwater acoustic communication networking is performed, thereby improving the efficiency of establishing the underwater acoustic communication network.

[0021] S2, the underwater acoustic communication network receives the frequency modulation signal sent by the mobile node, processes and summarizes it, and obtains a summary signal; Specifically, in step S2, the underwater acoustic communication network receives the frequency modulation signal sent by the mobile node, processes and aggregates it, and the method steps for obtaining the aggregated signal are as follows: S21, designating one of the four buoys as a main buoy and the other three as secondary buoys; S22, the three auxiliary submerged buoys and the main submerged buoy all receive the frequency modulation signal, and process the frequency modulation signal to obtain a communication signal; S23, transmitting the communication signals of the remaining three auxiliary submerged buoys to the main submerged buoy for aggregation to obtain an aggregated signal.

[0022] Furthermore, the communication signals of the remaining three auxiliary submerged buoys are transmitted to the main submerged buoy for aggregation, and the method steps for obtaining the aggregated signal are as follows: S231, cross-correlate the frequency modulation signals received by the three secondary buoys and the main buoy with the original frequency modulation signal of the signal parameters set by the transmitting end to find the maximum correlation peak, and obtain the propagation time according to the maximum correlation peak; S232. The three secondary buoys convert the acquired propagation time data into communication signals within a predetermined frequency band through OFDM modulation technology, and send them to the main buoy through the underwater acoustic channel for aggregation to obtain an aggregated signal.

[0023] Furthermore, the method steps of cross-correlating the frequency modulation signals received by the three secondary buoys and the main buoy with the original frequency modulation signals of the signal parameters set by the transmitting end to find the maximum correlation peak, and obtaining the propagation time according to the maximum correlation peak are as follows: The generalized cross-correlation method is used to perform Fourier transform on the cross-correlation function to obtain the cross-power spectrum, and the frequency domain relationship between the signals is analyzed. After obtaining the cross-power spectrum, the generalized cross-correlation method uses a specific weighting function for weighted processing, and then the frequency modulation signals received by the three secondary buoys and the main buoy are generalized cross-correlated with the original frequency modulation reference signal sent by the mobile node to find the maximum correlation peak, and the signal propagation time is obtained, so as to effectively reduce the interference of noise and reverberation in the environment, improve the reliability of the signal and the detectability of the peak value, and by using a suitable weighting strategy, the signal-to-noise ratio of the signal can be significantly improved, so that the required peak value is more prominent, thereby better extracting the information of the potential signal; The calculation formula of the generalized cross-correlation method is:

[0024] in, is the cross-spectrum, is the frequency domain weighting function, is a constant, For plural units, For variables, is the signal delay.

[0025] Furthermore, the delay is obtained by finding the peak value of the cross-correlation function. The delay calculation formula is:

[0026] Specifically, the transmission of signals mainly adopts OFDM modulation and demodulation technology. First, the information to be transmitted is encoded. This process includes signal modulation, encoding and allocation to each subcarrier. In the OFDM signal, the entire spectrum is divided into multiple subcarriers, each subcarrier carries a part of the information, and these subcarriers are orthogonal. They can be transmitted in parallel on the same frequency band without interfering with each other. The modulated signal carried on each subcarrier is part of the information, and the information can be embedded by adjusting the phase, amplitude, etc. of each subcarrier. Once the information is embedded in the subcarrier through the encoding and modulation process, the OFDM signal is ready to be sent. The OFDM signal obtained by modulation at the transmitter is transmitted through the underwater acoustic channel, which usually contains information carried by multiple subcarriers. At the receiving end, the OFDM signal is converted back to the frequency domain through FFT (Fast Fourier Transform) to demodulate the received signal and extract the data information on each subcarrier.

[0027] S3, using the TDOA algorithm to solve the summary signal to obtain the location information of the mobile node, and then sending the location information to the surface ship terminal; Furthermore, in step S3, the method steps of using the TDOA algorithm to solve the summary signal to obtain the location information of the mobile node, and then sending the location information to the surface ship terminal are as follows: S31, using OFDM demodulation technology at the main latent beacon to demodulate the summary information to obtain delay information; S32, calculating the delay information by using the TDOA algorithm to obtain the location information of the mobile node; S33, then sending the location information to the surface ship terminal, so as to facilitate displaying the accurate location information of the mobile node to the surface personnel.

[0028] Specifically, when the main buoy receives the communication signals from the other three sub-buoys, it demodulates the delay information in the communication signal through OFDM, and then uses the delay information to perform the least squares method in the TDOA algorithm to solve the location information of the mobile node target, and then adds the location information to the communication signal and sends it to the blowing ship terminal.

[0029] Specifically, the TDOA positioning model refers to FIG5, where: are the coordinates of the target node to be located, , It is a potential mark The coordinates of , from which the equation is:

[0030]

[0031] in, is the intersection equation of the hyperbolic model, There are three potential The distance to the mobile node to be located minus the distance to the main buoy The distance to the mobile node target to be located improves the accuracy of positioning the mobile node target.

[0032] Further, such as Figures 2 to 4 As shown, in order to verify the positioning performance of the mobile node positioning method of this embodiment, the following experiment is carried out. In a sea area, an underwater mobile target, an acoustic signal collector and four buoys are deployed. The underwater mobile node target moves in a uniform straight line in a rectangular area formed by the four buoys, with a depth of 4 meters and a speed of 2 knots (about 1.03 meters per second). The mobile node actively transmits acoustic signals for detection, and the four buoys numbered 2, 9, 10, and 21 are responsible for receiving these acoustic signals; The collector acts as an array element in the experiment. It is connected to the underwater transducer and collects underwater acoustic signals in real time. During the experiment, the GPS position and depth information of the buoy and the underwater mobile node target were recorded. The collected data was processed and transmitted to the upper computer software of the display and control platform through cables. Finally, the positioning trajectory was presented on the software interface. The positioning result was highly consistent with the actual value of the target, which proved the reliability of the invention. In the case of low measurement noise, only four buoys can be used to effectively calculate the position and speed of the underwater mobile node target, saving costs, simple operation, and suitable for underwater mobile node positioning in a small area.

[0033] The terms "first", "second", "third", "fourth", etc. (if any) in the specification of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein, for example. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0034] As described above, the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for positioning a mobile node based on an underwater acoustic communication network, characterized in that: The following steps are involved: S1. Check whether the submerged buoy can normally send and receive signals. If the submerged buoy can normally send and receive signals, the submerged buoy is placed at a predetermined underwater position to form an underwater acoustic communication network. The step of placing the buoy at a predetermined underwater position for underwater acoustic communication networking specifically includes: before starting to place the buoy, the placement position of the buoy needs to be designed in advance according to the position of the mobile node; The four submerged buoys are placed in a rectangular shape, the placement position is located by GPS, and then the submerged buoys are placed, and an underwater acoustic communication network is formed; the underwater acoustic communication network is composed of the four submerged buoys; S2, the underwater acoustic communication network receives the frequency modulation signal sent by the mobile node, processes and summarizes it, and obtains a summary signal; The underwater acoustic communication network receives the frequency modulation signal sent by the mobile node, processes and summarizes it, and the method steps for obtaining the summary signal are as follows: designate one of the four buoys as a primary buoy and the other three as secondary buoys; The three auxiliary submerged buoys and the main submerged buoy all receive the frequency modulation signal, and process the frequency modulation signal to obtain a communication signal; Then the communication signals of the remaining three auxiliary submerged buoys are transmitted to the main submerged buoy for aggregation to obtain an aggregated signal; S3. Use the TDOA algorithm to solve the summary signal to obtain the location information of the mobile node, and then send the location information to the surface ship terminal.

2. A method for positioning a mobile node based on an underwater acoustic communication network according to claim 1, characterized in that: The communication signals of the remaining three auxiliary submerged buoys are then transmitted to the main submerged buoy for aggregation to obtain the aggregated signal in the following steps: Perform cross-correlation processing on the frequency modulation signals received by the three secondary buoys and the main buoy and the original frequency modulation signal of the signal parameters set by the transmitting end to find the maximum correlation peak, and obtain the propagation time according to the maximum correlation peak; The three auxiliary buoys convert the acquired propagation time data into communication signals within a predetermined frequency band through OFDM modulation technology, and send them to the main buoy through the hydroacoustic channel for aggregation to obtain an aggregated signal.

3. A method for positioning a mobile node based on an underwater acoustic communication network according to claim 2, characterized in that: In step S3, the method steps of using the TDOA algorithm to solve the summary signal to obtain the location information of the mobile node, and then sending the location information to the surface ship terminal are as follows: Using OFDM demodulation technology at the main buoy to demodulate the summary information to obtain delay information; Then, the time delay information is solved by using a TDOA algorithm to obtain the location information of the mobile node; The position information is then sent to the surface ship terminal.

4. The method for positioning a mobile node based on an underwater acoustic communication network according to claim 2, characterized in that: The method steps of cross-correlating the frequency modulation signals received by the three auxiliary buoys and the main buoy with the original frequency modulation signals of the signal parameters set by the transmitting end to find the maximum correlation peak, and obtaining the propagation time according to the maximum correlation peak are as follows: The generalized cross-correlation method is used to perform Fourier transform on the cross-correlation function to obtain the cross-power spectrum, and the frequency domain relationship between the signals is analyzed. After obtaining the cross-power spectrum, the generalized cross-correlation method uses a specific weighting function for weighted processing, and then the frequency modulation signals received by the three secondary buoys and the main buoy are generalized cross-correlated with the original frequency modulation reference signal sent by the mobile node to find the maximum correlation peak and obtain the signal propagation time; The calculation formula of the generalized cross-correlation method is: in, is the cross-spectrum, is the frequency domain weighting function, is a constant, For plural units, For variables, is the signal delay.

5. The method for positioning a mobile node based on an underwater acoustic communication network according to claim 1, characterized in that: In step S1, the method steps for checking whether the latent buoy can normally send and receive signals are as follows: Connect an initial submersible to the UartAssist serial debugging assistant; The initial latent beacon is controlled to send an audio signal by issuing a serial port instruction for audio transmission, and then the audio signal is received by another latent beacon to be tested. If the tested latent buoy receives the audio signal normally and sends back a feedback audio signal to the initial latent buoy, the feedback audio signal is displayed on the UartAssist serial port debugging assistant, proving that both latent buoys are sending and receiving audio signals normally.

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