CN114609620A - Underwater positioning method and system - Google Patents

Abstract

The invention provides an underwater positioning method and a system thereof, wherein the underwater positioning system comprises: the device comprises an optical signal processing device, an optical submarine cable and a target to be positioned. One end of the submarine optical cable is connected with the optical signal processing device, and the optical signal processing device controls the light source to emit optical signals which are transmitted in the submarine optical cable which is laid in advance. A vibration source is arranged in the target to be positioned, and a sound wave signal is generated by the vibration source and acts along the submarine optical cable. According to the underwater positioning method and the system thereof, a plurality of vibration sources are not needed, the positioning process can be completed through a single vibration source, the target to be positioned can obtain the absolute position of the target to be positioned without floating up to obtain a GPS positioning signal, a mother ship does not need to follow the action, the ship time is saved in ocean detection, and meanwhile, the cost can be obviously reduced.

Description

An underwater positioning method and system thereof

technical field

The invention belongs to the field of underwater positioning, and in particular relates to an underwater positioning method and a system thereof, in particular to an underwater positioning method and a system thereof with accurate and rapid positioning and low cost.

Background technique

Autonomous Underwater Vehicles (AUV), as an emerging marine equipment with underwater mobility, underwater concealment and cluster work ability, can complete seabed exploration, underwater facility maintenance and underwater parameter data collection. and many other underwater missions. In order to efficiently and accurately complete underwater operations, the precise positioning of AUVs is a top priority.

The existing AUV underwater navigation and positioning technology is mainly based on the method of self-carrying sensors, using pure inertial navigation system, and integrating auxiliary equipment such as Doppler speedometer and attitude reference system. Due to the inherent shortcomings of the inertial navigation system, the positioning error of the inertial navigation system continues to accumulate with the increase of navigation time, and the positioning and navigation accuracy is gradually lost. At the same time, different from land systems, navigation in water is seriously affected by currents, and the continuous fluctuation of ocean currents will further accelerate the accumulation of inertial navigation system errors, and the cumulative effect of this error can even reach more than a thousand times the nominal error of the system.

In order to solve this problem, the researchers propose a method of correcting through external information. One of the methods uses the GPS system to correct the absolute position of the AUV. However, since the electromagnetic wave signal cannot penetrate the water body, the AUV for marine operations is similar to GPS. This positioning method can only locate near the ocean surface, which makes the AUV less stealthy and interrupts the ongoing mission. Another solution is to use acoustic positioning sensors to achieve absolute position positioning by pre-arranging surface buoys or underwater sinks. However, this method requires a large number of operating vessels to place the beacon reference objects, which is costly and time-consuming.

The current mainstream positioning method is the joint positioning method combining external correction and AUV's own sensor. Patent CN111595348 A discloses a master-slave cooperative positioning method of an AUV integrated navigation system. The master AUV broadcasts its own position information, and the AUV obtains the relative distance between the two times according to the speed of sound and time delay, and then the master AUV uses the speed measurement information. 、Ranging information to co-locate any slave AUV, correct the distance between the two, and reduce the error of AUV positioning. In the master-slave co-location method based on AUV disclosed in the patent CN 111595348 A, multiple AUVs can share information between AUVs in each positioning cycle, and use the speed of sound and time delay to obtain the relative distance between the two time to make each AUV The positioning accuracy reaches the same order of magnitude, and the positioning capability is restored to a certain extent. However, currently only one AUV is needed in the main working scenarios of AUVs to complete the underwater operation task. Using the method described in this patent requires additional customized AUVs for positioning, resulting in extremely high additional costs; at the same time, This co-location method cannot completely correct the absolute error. In order to control the error divergence, this method still requires the main AUV to float up regularly to obtain GPS positioning information, which will interrupt the execution of underwater tasks.

Patent CN 110057365 A discloses a deep diving AUV positioning method. In this method, the AUV is equipped with an underwater communication node, an inertial navigation system and a temperature and salinity sensor. By combining the coordinate system position information and time information sent by the communication between the surface mother ship and the underwater AUV, and the inertial navigation information and temperature and salinity recorded by the AUV The sensor information builds a distance model between the AUV and the mother ship, and then integrates the positioning information of the mother ship itself to complete the online correction of the positioning error. However, the application of ships in marine surveys is limited, and the cost of the mother ship is very large.

To sum up, the underwater positioning method of the prior art has high cost, and still needs to be corrected in order to maintain the relative accuracy, so the prior art needs to be improved.

SUMMARY OF THE INVENTION

The object of the present invention is to provide an underwater positioning method and a system thereof, wherein a light source sends out an optical signal to a submarine optical cable, a vibration source sends out an acoustic signal to act on the optical signal of the submarine optical cable, and combined with the construction route map of the submarine optical cable, the target to be located is realized. position.

In order to achieve the above object, a kind of underwater positioning method provided by the present invention comprises the following steps:

Step 1, the optical signal processing device sends an optical signal to the submarine optical cable through a light source, and the optical signal enters the receiving unit and is converted into an electrical signal to obtain a reference detection signal q;

Step 2, the target to be positioned sends out an acoustic wave signal S through a vibration source located inside the target to be positioned, and the acoustic wave signal S acts on the optical signal in the submarine optical cable to obtain a detection signal t1;

Step 3, subtract the reference detection signal q in the step 1 from the detection signal t1 in the step 2 to obtain the sound wave detection signal S1 that the vibration source acts on the submarine optical cable, and select the Describe the maximum signal amplitude point A1 of the acoustic wave detection signal S1;

Step 4, obtain the construction route map of submarine optical cable, and obtain the positioning of the target to be located based on the sound wave detection signal S1, the maximum point A1 of the signal amplitude and the construction route map of the submarine optical cable.

Further, before the step 4, it is judged whether the intensity of the sound wave detection signal S1 reaches the preset threshold value, if so, enter the step 4; if not, make the target to be located move and repeat the step 2.

Further, the light source and the receiving unit are respectively connected to the same end of the submarine optical cable, the light source sends an optical signal to the submarine optical cable, and the receiving unit receives the backscattered signal of the optical signal.

Further, the optical signal processing device is an optical time domain reflectometry device.

Further, the optical time domain reflectometry device is a φ-OTDR reflectometer; or

The optical time domain reflectometry device is a c-OTDR reflectometer.

Further, in the step 4, the intensity of the sound wave detection signal S1 in the step 3 is substituted into the relationship between the preset sound wave detection signal strength S1 and the distance between the target to be located and the submarine optical cable, to obtain The distance between the target to be located and the submarine optical cable.

Further, based on the time difference between the speed of light v of the optical signal in the submarine optical cable and the zero point where the signal amplitude maximum point A1 is connected to the optical time domain reflection device, the target to be located and the optical signal are obtained. Distance between time domain reflectometry devices.

Further, the target to be located is an underwater autonomous vehicle.

Further, the step 1 and the step 2 also include signal preprocessing, and the signal preprocessing is moving average method, wavelet denoising method, curvelet transform denoising method, compressed sensing denoising method, and empirical mode decomposition denoising method. One or more of noise method or neural network method.

An underwater positioning system, comprising a vibration source, a submarine optical cable and an optical signal processing device, the optical signal processing device comprising a light source, a receiving unit and a control unit;

the light source is used to generate an optical signal;

The submarine optical cable is used for transmitting optical signals;

The vibration source is arranged in the target to be located and is used to emit sound waves and act on the optical signal;

The receiving unit is used to receive the optical signal and convert it into an electrical signal, and then transmit it to the control unit;

The control unit is used to control the light source and the receiving unit, and further includes a calculation module, and the calculation module is used to execute the underwater positioning method according to any one of claims 1-9.

Further, the optical signal processing device is an optical time domain reflectometry device.

Further, the optical time domain reflectometry device is a φ-OTDR reflectometer; or

The optical time domain reflectometry device is a c-OTDR reflectometer.

Further, the vibration source is an engine or a broadcast sound source.

The present invention has at least the following beneficial effects: the present invention provides an underwater positioning method and a system thereof, which does not require the use of multiple vibration sources, the positioning process can be completed through a single vibration source, and does not require the target to be positioned to float up to obtain GPS positioning signals , the absolute position of the target to be located can be obtained, and the mother ship is not required to follow the action, which saves the ship's time in ocean exploration and can significantly reduce the cost.

The target to be located in the present invention is an underwater autonomous vehicle, which is an emerging marine equipment with underwater movement flexibility, underwater concealment and cluster work ability, and can complete seabed exploration, underwater facility maintenance and underwater parameter data collection and other underwater tasks, combined with the underwater positioning method of the present invention, the underwater operation can be completed efficiently and accurately.

Description of drawings

The present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments.

FIG. 1 is a flowchart of an underwater positioning method according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of an underwater positioning system according to an embodiment of the present invention.

In the picture: 1-φ-OTDR reflectometer, 2- submarine optical cable, 3-AUV, S1- acoustic detection signal, A1- maximum amplitude point.

Detailed ways

In order to make the objects, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.

The specific implementation of the present invention will be described in detail below in conjunction with specific embodiments. Although the following embodiments take AUV as an example, it is obvious that the present invention can also be used as an independent position tracking and navigation method and system. Therefore, the target to be located in the embodiment is It is not intended to limit the present invention.

In order to solve the shortcomings of the prior art, that is, the high cost of underwater positioning, and the need for floating correction to maintain accuracy, the present invention proposes an underwater positioning method and a system thereof. The invention sends out optical signals to the submarine optical cable 2 through the light source, and the vibration source in the target to be positioned vibrates to generate sound wave signals, which act on the optical signal of the submarine optical cable 2, and then determine the target to be positioned through the solution module and the construction route map of the submarine optical cable. positioning. The specific steps are as follows:

Figure 1 shows the steps of an underwater positioning method according to an embodiment of the present invention, including:

Step 1, the optical signal processing device sends an optical signal to the submarine optical cable 2 by a light source, and the optical signal enters the receiving unit and is converted into an electrical signal to obtain a reference detection signal q;

Step 2, the target to be positioned sends out sound wave signal S by the vibration source positioned inside the target to be positioned, and the sound wave signal S acts on the optical signal of submarine optical cable 2, obtains detection signal t1;

Step 3, the reference detection signal q in the step 2 is subtracted from the detection signal t1 in the step 2, obtains that the vibration source acts on the acoustic wave detection signal S1 along the submarine optical cable 2, chooses the signal amplitude maximum point A1 of the acoustic wave detection signal S1;

Step 4: Obtain the construction route map of the submarine optical cable, and obtain the location of the target to be located based on the acoustic wave detection signal S1, the maximum signal amplitude point A1 and the construction route map of the submarine optical cable.

Further, before the above step S4, determine whether the intensity of the sound wave detection signal S1 reaches a preset threshold, if so, go to the next step; if not, continue to move the target to be located and repeat step 2. In practical application scenarios, if the requirements for positioning accuracy are high, the threshold needs to be increased to meet the requirements.

The optical signal processing device of the present invention is an optical time domain reflection device. By injecting optical signals into the submarine optical cable 2 and analyzing the reflected multiple optical signals arranged in order of detection time, it is helpful to realize accurate and rapid underwater positioning. . In the present invention, the optical time domain reflectometry device is a φ-OTDR reflectometer 1 .

The target to be located in the present invention is AUV3, which is an emerging marine equipment with underwater movement flexibility, underwater concealment and cluster work ability, and can complete a number of marine equipment such as seabed exploration, underwater facility maintenance, and underwater parameter data collection. For the next task, combined with the underwater positioning method of the present invention, the underwater operation can be completed efficiently and accurately.

The light source and the receiving unit are respectively connected to the same end of the submarine optical cable 2, the light source sends an optical signal to the submarine optical cable 2, and the receiving unit receives the backscattered signal of the optical signal.

In step 1, the φ-OTDR reflector 1 emits an optical signal through the light source, and propagates in the pre-laid submarine optical cable 2 . Since all positions along the submarine optical cable 2 will return the Rayleigh scattered light, a continuous Rayleigh scattered light intensity signal arranged in order of detection time can be detected in the φ-OTDR reflector 1. The signal amplitude at each time point Each value corresponds to the Rayleigh scattered light intensity at a certain location. The external information distributed along the optical cable is restored by the φ-OTDR reflector 1, and then the background noise of the seabed environment during the detection process is eliminated by the signal preprocessing method to obtain the reference detection signal q. The signal preprocessing method includes but is not limited to moving average method, wavelet denoising method, curvelet transform denoising method, compressed sensing denoising method, empirical mode decomposition denoising method and neural network method.

In step 2, the AUV3 sends out a sound wave signal S with a certain amplitude and frequency through the vibration source; the detection is carried out through the φ-OTDR technology, and the external disturbance information distributed along the submarine optical cable 2 and the sound wave signal generated by the AUV3 are obtained in the φ-OTDR reflector 1. S, and then obtain the detection signal t1 after eliminating external disturbance information such as environmental background noise through the same signal preprocessing method as in step 1.

In step 3, the point A1 with the maximum signal amplitude corresponds to the point on the submarine optical cable 2 with the smallest distance from the AUV3.

In step 4, the intensity of the sound wave detection signal S1 of step 3 is substituted into the relationship between the preset sound wave detection signal strength S1 and the distance between the target to be located and the submarine optical cable to obtain the distance between the target to be located and the submarine optical cable. The distance between the maximum amplitude point A1 of the vibration signal and the φ-OTDR reflector 1 can be calculated by the calculation module in the processing unit of the φ-OTDR reflector 1. The time difference between zero points is multiplied by the speed of light v in submarine cable 2 and divided by 2.

In addition, the φ-OTDR reflector 1 of the present invention can be replaced by a C-OTDR reflector, and the replacement is only a transformation of the vibration signal measurement method of the submarine optical cable, and the measurement process remains unchanged.

Referring to Figure 2 of the description, it is a schematic diagram of an underwater positioning system according to an embodiment of the present invention, including a φ-OTDR reflector 1 based on Rayleigh scattering, a submarine optical cable 2 and an AUV3. The φ-OTDR reflectometer 1 includes a light source, a receiving unit and a control unit. The light source is used to generate the optical signal, the submarine optical cable 2 is used to transmit the optical signal, and a vibration source is set in the AUV3, which is used to send out the acoustic signal S and act on the optical signal of the submarine optical cable 2. The control unit is used to control the light source and the receiving unit, and also includes a calculation module, the calculation module is used to process the electrical signal, and the electric signal is input into the calculation module to obtain the positioning of the target to be positioned.

When implementing the AUV3 positioning of the present invention, one end of the submarine optical cable 2 is connected to the φ-OTDR reflector 1 as an optical time domain reflector, and the control unit of the φ-OTDR reflector 1 controls the light source to send out an optical signal. 2, the receiving unit receives the backscattered signal of the optical signal and converts it into an electrical signal. Among them, the submarine optical cable 2 can be the original submarine optical cable 2, or the optical cable can be laid by itself in the AUV3 mission area. The AUV3 generates a sound wave signal S through a vibration source and acts on the submarine optical cable 2 along the line. The position of the vibration source in the AUV3 can be adjusted according to the needs of the AUV3. Among them, vibration sources can generate vibration or sound waves, including but not limited to engines with unique vibration, broadcast sound sources, etc.

Therefore, the present invention provides an underwater positioning method and a system thereof, which do not need to use multiple vibration sources, and can complete the positioning process through a single vibration source, without the need for the target to be positioned to float up to obtain a GPS positioning signal, and can obtain the undetermined positioning signal. The absolute position of the target is not required, and the mother ship does not need to follow the action, which saves the ship's time in ocean exploration and can significantly reduce the cost.

The above descriptions are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention shall be included in the protection of the present invention. within the range.

Claims (13)

1. an underwater positioning method, is characterized in that, comprises the following steps: Step 1, the optical signal processing device sends an optical signal to the submarine optical cable through the light source, the optical signal enters the receiving unit and is converted into an electrical signal to obtain a reference detection signal q; Step 2, the target to be located sends out an acoustic wave signal S through a vibration source located inside the target to be located, and the acoustic wave signal S acts on the optical signal in the submarine optical cable to obtain a detection signal t1; Step 3, subtract the reference detection signal q in the step 1 from the detection signal t1 in the step 2 to obtain the sound wave detection signal S1 that the vibration source acts on the submarine optical cable, and select the Describe the maximum signal amplitude point A1 of the acoustic wave detection signal S1; Step 4: Obtain a submarine optical cable construction route map, and obtain the location of the to-be-located target based on the acoustic wave detection signal S1, the signal amplitude maximum point A1 and the submarine optical cable construction route map. 2. underwater positioning method according to claim 1, is characterized in that, before described step 4, judge whether described sound wave detection signal S1 intensity reaches preset threshold value, if so, enter step 4; If not, Continue to move the to-be-located target and repeat step 2. 3. The underwater positioning method according to claim 1, wherein the light source and the receiving unit are respectively connected to the same end of the submarine optical cable, the light source sends an optical signal to the submarine optical cable, and the The receiving unit receives the backscattered signal of the optical signal. 4 . The underwater positioning method according to claim 1 , wherein the optical signal processing device is an optical time domain reflectometry device. 5 . 5. underwater positioning method according to claim 4, is characterized in that, described optical time domain reflectance device is φ-OTDR reflectometer; Or The optical time domain reflectometry device is a c-OTDR reflectometer. 6. The underwater positioning method according to claim 1, wherein in the step 4, the intensity of the acoustic wave detection signal S1 in the step 3 is substituted into the preset intensity of the acoustic wave detection signal S1 and The relationship between the distance between the to-be-located target and the submarine optical cable obtains the distance between the to-be-located target and the submarine optical cable. 7 . The underwater positioning method according to claim 1 , wherein the optical time domain reflectometry device is connected to the optical time domain reflection device based on the speed of light v of the optical signal in the submarine optical cable and the signal amplitude maximum point A1 . The time difference between the zero points of , obtains the distance between the target to be positioned and the optical time domain reflectometry device. 8 . The underwater positioning method according to claim 1 , wherein the target to be positioned is an underwater autonomous vehicle. 9 . 9. underwater positioning method according to claim 1, is characterized in that, described step 1 and described step 2 also comprise signal preprocessing, and described signal preprocessing is moving average method, wavelet denoising method, curvelet One or more of transform denoising method, compressed sensing denoising method, empirical mode decomposition denoising method or neural network method. 10. An underwater positioning system, comprising a vibration source, a submarine optical cable and an optical signal processing device, the optical signal processing device comprising a light source, a receiving unit and a control unit; the light source is used to generate an optical signal; The submarine optical cable is used for transmitting optical signals; The vibration source is arranged in the target to be located and is used to emit sound waves and act on the optical signal; The receiving unit is used to receive the optical signal and convert it into an electrical signal, and then transmit it to the control unit; The control unit is used to control the light source and the receiving unit, and further includes a calculation module, and the calculation module is used to execute the underwater positioning method according to any one of claims 1-9. 11. The underwater positioning system according to claim 10, wherein the optical signal processing device is an optical time domain reflectometry device. 12. The underwater positioning system according to claim 11, wherein the optical time domain reflectometry device is a φ-OTDR reflectometer; or The optical time domain reflectometry device is a c-OTDR reflectometer. 13. The underwater positioning system according to claim 10, wherein the vibration source is an engine or a broadcast sound source.

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