Arctic pole ice region seabed magnetotelluric instrument underwater acoustic positioning system and method

Abstract

The invention discloses an underwater acoustic positioning system and method for a seabed magnetotelluric instrument in an arctic ice region, and belongs to the technical field of underwater positioning, the system comprises shipborne equipment and underwater equipment, the shipborne equipment is arranged on a scientific investigation ship, and the underwater equipment is arranged on the seabed magnetotelluric instrument; the shipborne equipment comprises an underwater sound deck unit, a ship bottom visual array and an underwater upward visual array; the underwater equipment comprises an underwater beacon which can be switched between an upper view mode and a lower view mode; the underwater sound deck unit is used for sending a control instruction to the underwater beacon and receiving position information; the ship bottom view array is installed at the bottom of a scientific investigation ship body and communicates with the underwater beacons in the upper view mode. The underwater upward-looking array is connected with the scientific investigation ship body through a cable and can be put in a sea area to communicate with the underwater beacon in the downward-looking mode. According to the invention, underwater acoustic positioning of the subglacial instrument can be realized, the salvage efficiency of the subglacial seabed magnetotelluric instrument is greatly improved, and the instrument data safety is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of underwater positioning, and particularly to an underwater acoustic positioning system and method for a submarine magnetotelluric instrument in the Arctic ice area. Background Art

[0002] The submarine magnetotelluric detection method is an important and effective means for detecting the deep structure of the ocean floor, with the advantages of large detection depth, sensitive identification of high-conductivity anomalies, high operation efficiency, and low operation cost. For the recovery of submarine magnetotelluric detection devices, most commonly use the positioning methods of surface instruments and radio positioning.

[0003] The method of positioning surface instruments is mainly used to assist ships in searching and salvaging. Specific technologies include visual observation, radio positioning, etc. Common methods of visual observation include tying red flags and installing high-brightness LED lights on the instrument. This method is relatively simple to implement and suitable for close-range observation. However, in the ice-covered environment of the Arctic, red flags and LED lights are ineffective during the polar day and when there is ice.

[0004] Common methods of radio positioning include radio direction finding, Iridium positioning, GPS & RF modules, etc. Radio direction finding uses the signal strength difference between antennas to determine the target direction, with slightly poor accuracy. Iridium positioning mainly uses satellites as a communication medium to achieve ultra-long-range communication, but it requires additional satellite service subscriptions and has a high cost. GPS & RF modules generally obtain the position through the GPS module and then send the position to the RF receiving terminal through the RF module. The positioning accuracy is relatively high, but the integration degree is low and an additional shipborne radio receiving end needs to be designed.

[0005] The Arctic region has a harsh environment and is covered by ice all year round. When the instrument is attached under the ice sheet, traditional technologies such as red flags, LEDs, GPS, and Iridium radios are not applicable.

[0006] In the prior art, underwater instrument positioning is most commonly based on the ultra-short baseline USBL technology, which mainly consists of an underwater acoustic deck unit, a ship bottom array, and an underwater positioning beacon. By establishing communication between the underwater positioning beacon and the ship bottom array through sound waves, precise positioning of the underwater positioning beacon is achieved. This method can not only achieve positioning and tracking during the sinking and floating processes of underwater equipment, but also achieve the acoustic release of underwater equipment.

[0007] However, when the traditional USBL underwater acoustic positioning scheme operates in the polar ice sheet waters, when the instrument floats up under the ice sheet, affected by the sea ice interface, sound wave scattering and sound ray bending occur, and a reliable underwater acoustic channel cannot be established between the ship bottom array and the underwater positioning beacon, and the underwater acoustic positioning technology encounters obstacles.

[0008] Therefore, it is urgent to break through the obstacles of the existing technical solutions and seek an underwater acoustic positioning method suitable for sub-ice instruments.

[0009] The information disclosed in this background section is only intended to enhance the overall understanding of the background of the present invention and should not be regarded as an admission or any form of implication that this information constitutes prior art already known to those of ordinary skill in the art. Summary of the Invention

[0010] An object of the present invention is to provide an underwater acoustic positioning system and method for a submarine magnetotelluric instrument in the Arctic ice area, which can achieve underwater acoustic positioning, greatly improve the recovery efficiency of the underwater submarine magnetotelluric instrument, and ensure the safety of instrument data.

[0011] To achieve the above object, the present invention provides an underwater acoustic positioning system for a submarine magnetotelluric instrument in the Arctic ice area, including a shipborne device and an underwater device. The shipborne device is arranged on a scientific research ship, and the underwater device is arranged on the submarine magnetotelluric instrument. It is characterized in that the shipborne device includes an underwater acoustic deck unit, a bottom-looking array under the ship, an upward-looking array underwater, and an upward-looking beacon underwater; the underwater device includes an underwater beacon that can switch between an upward-looking mode and a downward-looking mode.

[0012] The underwater acoustic deck unit is used to control the bottom-looking array under the ship and the upward-looking array underwater to send control commands to the underwater beacon, receive the response signals sent by the underwater beacon, and calculate the position information of the beacon.

[0013] The bottom-looking array under the ship is installed at the bottom of the hull of the scientific research ship and can communicate with the underwater beacon in the upward-looking mode to obtain the position of the underwater device.

[0014] The upward-looking array underwater is connected to the hull of the scientific research ship through a cable and can be deployed in the sea area to communicate with the underwater beacon in the downward-looking mode to obtain the position of the underwater device.

[0015] When the underwater device is in the three stages of sinking, at the seabed, and floating, the underwater beacon enables the upward-looking mode to acoustically communicate with the bottom-looking array under the ship to achieve the positioning of the underwater device; when the underwater device floats up under the ice cover, it switches to the downward-looking mode and acoustically communicates with the upward-looking array underwater to achieve the positioning of the underwater device.

[0016] In an embodiment of the present invention, the depth at which the upward-looking array underwater is deployed in the sea area is 80 to 120 meters.

[0017] In an embodiment of the present invention, the depth at which the upward-looking array underwater is deployed in the sea area is 100 meters.

[0018] In an embodiment of the present invention, the upward-looking beacon underwater is also provided on the cable connecting the upward-looking array underwater to the hull, which is used to communicate with the bottom-looking array under the ship to achieve the positioning of the upward-looking array underwater.

[0019] In an embodiment of the present invention, the underwater upward-looking array is disposed above and near the underwater upward-looking beacon.

[0020] In an embodiment of the present invention, the underwater device further includes a pressure-resistant cabin, and the underwater beacon includes an upward-looking transducer and a downward-looking transducer; an underwater acoustic communication module is disposed in the pressure-resistant cabin; the underwater acoustic communication module is connected to the upward-looking transducer and the downward-looking transducer, and is respectively used for underwater acoustic positioning and data transmission with the bottom downward-looking array of the ship and the underwater upward-looking array.

[0021] In an embodiment of the present invention, the underwater device further includes an electro-corrosion decoupler disposed outside the pressure-resistant cabin; the electro-corrosion decoupler is connected to a counterweight through a cable, and can receive an instruction from the underwater acoustic communication module to fuse the cable connected to the counterweight.

[0022] In an embodiment of the present invention, a glass float is further disposed on the underwater device.

[0023] The present invention also provides a positioning method for the underwater acoustic positioning system of the above-mentioned Arctic ice area seafloor magnetotelluric instrument, including the following steps:

[0024] S1: Set the acquisition parameters of the seafloor magnetotelluric instrument and start data acquisition;

[0025] S2: Drop the seafloor magnetotelluric instrument into the sea area to perform magnetotelluric signal measurement;

[0026] S3: During the sinking process of the seafloor magnetotelluric instrument, the bottom downward-looking array of the ship communicates with the underwater beacon in the upward-looking mode to perform positioning and tracking during the sinking and landing processes;

[0027] S4: After the underwater measurement is completed, the bottom downward-looking array of the ship sends an instruction. After the underwater acoustic communication module receives the instruction, it starts the electro-corrosion decoupler. After the electro-corrosion decoupler is powered on, it releases the counterweight, and the seafloor magnetotelluric instrument floats up;

[0028] S5: During the floating-up process, the bottom downward-looking array of the ship communicates with the underwater beacon in the upward-looking mode to achieve positioning and tracking during the instrument floating-up process;

[0029] S6: After the instrument reaches near the ice surface, according to the depth change judgment, switch the underwater beacon to the downward-looking mode, and deploy the underwater upward-looking array into the sea area to communicate with the underwater beacon in the downward-looking mode to achieve underwater acoustic positioning;

[0030] S7: Rely on the icebreaker to break the ice and go to the positioning location to salvage the seafloor magnetotelluric instrument under the ice.

[0031] In an embodiment of the present invention, in step S6, the time for the instrument to reach the ice surface is predicted according to both the floating speed and the instrument depth.

[0032] Compared with the prior art, according to a hydroacoustic positioning system and method for a submarine magnetotelluric instrument in the Arctic ice region of the present invention, compared with the traditional USBL positioning scheme that communicates with the downward-looking array by means of an upward-looking transducer, when the instrument floats to the ice surface, the upward-looking array is deployed 100 m below the ice surface to communicate with the downward-looking transducer carried by the instrument, so as to realize underwater hydroacoustic positioning. The salvage efficiency of the instrument is greatly improved and the instrument data security is ensured. It has the characteristics of high-precision positioning, high efficiency, low cost, high reliability, etc., and is suitable for the salvage and recovery work of instruments under the conditions of the Arctic ice region. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a schematic structural diagram of a hydroacoustic positioning system for a submarine magnetotelluric instrument in the Arctic ice region according to an embodiment of the present invention;

[0034] Figure 2 is a schematic diagram of signal interaction when the submarine magnetotelluric instrument is located on the seabed according to an embodiment of the present invention;

[0035] Figure 3 is a schematic structural diagram of an underwater device of a hydroacoustic positioning system for a submarine magnetotelluric instrument in the Arctic ice region according to an embodiment of the present invention;

[0036] Figure 4 is a flowchart of a hydroacoustic positioning method for a submarine magnetotelluric instrument in the Arctic ice region according to an embodiment of the present invention.

[0037] Description of the main reference numerals:

[0038] 1 - shipborne equipment, 2 - underwater equipment, 101 - hydroacoustic deck unit, 102 - downward-looking array under the ship bottom, 103 - upward-looking array underwater; 104 - upward-looking beacon underwater; 201 - underwater beacon; 2011 - upward-looking transducer; 2012 - downward-looking transducer; 202 - pressure-resistant cabin; 203 - electrocorrosion unhooking device; 204 - hydroacoustic communication module; 205 - lithium battery pack. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] The following will describe in detail the specific embodiments of the present invention with reference to the accompanying drawings, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments.

[0040] Unless otherwise clearly stated, throughout the specification and claims, the term "comprise" or its variations such as "comprises" or "comprising" etc. will be understood to include the stated elements or components, without excluding other elements or other components.

[0041] Under Arctic ice sheet conditions, the reliable and effective recovery of subsea instruments is one of the important aspects of ocean exploration. The key to recovery lies in the high-precision positioning of sub-ice instruments, and it is necessary to break through the ice once to discover the sub-ice instruments.

[0042] As Figures 1 to 3 shown, an underwater acoustic positioning system for a subsea magnetotelluric instrument in the Arctic ice area according to a preferred embodiment of the present invention can position the subsea magnetotelluric instrument under the ice.

[0043] An underwater acoustic positioning system for a subsea magnetotelluric instrument in the Arctic ice area of the present embodiment includes a shipborne device 1 and an underwater device 2. The shipborne device 1 is arranged on a scientific research ship, and the underwater device 2 is arranged on the subsea magnetotelluric instrument.

[0044] The shipborne device 1 includes: an underwater acoustic deck unit 101, a bottom-looking underwater array 102, an upward-looking underwater array 103, and an upward-looking underwater beacon 104. The underwater device 2 includes an underwater beacon 201, which supports both upward-looking and downward-looking modes.

[0045] The underwater acoustic deck unit 101 is the control center of the entire positioning system. The user can control the data interaction between the shipborne device 1 and the underwater device 2. Specifically, a control signal is sent to the underwater beacon of the underwater device 2, and the response signals received by the bottom-looking underwater array 102 and the upward-looking underwater array 103 are solved to obtain the position of the underwater device 2.

[0046] The bottom-looking underwater array 102 is installed at the bottom of the hull of the scientific research ship and can communicate with the upward-looking underwater beacon 201 in the sea area to obtain the position of the underwater device 2. The bandwidth of the signals received by the bottom-looking underwater array 102 is 7 - 14 kHz.

[0047] The upward-looking underwater array 103 is connected to the hull of the scientific research ship through a cable and can be deployed in the sea area to communicate with the downward-looking underwater beacon 201 to obtain the position of the underwater device 2. The depth at which the upward-looking underwater array 103 is deployed in the sea area is 80 to 120 meters, preferably 100 meters. The bandwidth of the signals received by the upward-looking underwater array 103 is 7 - 14 kHz.

[0048] An upward-looking underwater beacon 104 is also arranged on the cable connecting the upward-looking underwater array 103 to the hull, which is used to communicate with the bottom-looking underwater array 102 to obtain the position of the upward-looking underwater array 103 and realize the positioning of the upward-looking underwater array 103. Specifically, the upward-looking underwater array 103 is arranged above and close to the upward-looking underwater beacon 104. When encountering ocean currents, since the upward-looking underwater array 103 will drift and deviate from the water entry point, in order to obtain the accurate position of the underwater device 2, the acquisition of the position of the upward-looking underwater array 103 is a prerequisite. Therefore, the upward-looking underwater beacon 104 is designed to obtain the position of the upward-looking underwater array 103.

[0049] The underwater beacon 201 can switch between the upward-looking mode and the downward-looking mode. As Figure 2 shown, when the underwater device 2 is in the three stages of sinking, landing on the bottom, and floating upward, the underwater beacon 201 enables acoustic communication with the downward-looking array 102 under the ship in the upward-looking mode, sends a downward signal to the downward-looking array 102 under the ship, and the downward-looking array 102 under the ship calculates the position of the beacon to achieve the positioning of the underwater device. As Figure 1 shown, when the underwater device 2 floats up under the ice cover, it switches to the downward-looking mode, conducts acoustic communication with the upward-looking array 103 underwater, sends an upward signal to the upward-looking array 103 underwater, and the upward-looking array 103 underwater calculates the position of the beacon to achieve the positioning of the underwater device.

[0050] Specifically, as Figure 2 shown, the underwater device 2 further includes a pressure-resistant cabin 202 and an electro-corrosive decoupler 203 outside the pressure-resistant cabin 202.

[0051] The underwater beacon 201 includes an upward-looking transducer 2011 and a downward-looking transducer 2012. The upward-looking transducer 2011 and the downward-looking transducer 2012 communicate with the downward-looking array 102 under the ship and the upward-looking array 103 underwater respectively, that is, corresponding to the upward-looking mode and the downward-looking mode of the underwater beacon 201.

[0052] The pressure-resistant cabin 202, as the core carrier of the underwater device, provides physical protection and a high-pressure sealing environment for the internal electronic devices to ensure normal operation under the extreme water pressure at the seabed in the Arctic ice area. An underwater acoustic communication module 204 and a lithium battery pack 205 are arranged in the pressure-resistant cabin 202.

[0053] The underwater acoustic communication module 204 is connected to the upward-looking transducer 2011 and the downward-looking transducer 2012, and is used for underwater acoustic positioning and two-way data transmission with the downward-looking array 102 under the ship and the upward-looking array 103 underwater of the shipborne equipment, sending positioning information, control instructions, and device status feedback. The lithium battery pack 207 is used for power supply.

[0054] The electro-corrosive decoupler 203 is connected to the counterweight through a cable. Under the gravity of the counterweight, it can sink to the seabed. The electro-corrosive decoupler 203 can receive the instruction of the underwater acoustic communication module 204, fuse the cable connected to the counterweight, disconnect the connection with the counterweight, and then the underwater device 2 floats upward under the action of buoyancy. The counterweight can be a cement block, an iron block, etc.

[0055] A glass float can also be arranged on the underwater device 2 to provide buoyancy when floating upward.

[0056] As Figure 2As shown in the figure, a preferred embodiment of the present invention also provides an underwater acoustic positioning method for a seafloor magnetotelluric instrument in the Arctic ice area, which is mainly applied to an underwater acoustic positioning system for a seafloor magnetotelluric instrument in the Arctic ice area of the above preferred embodiment.

[0057] The positioning method includes:

[0058] S1: Set the acquisition parameters of the seafloor magnetotelluric instrument and start data acquisition.

[0059] S2: The seafloor magnetotelluric instrument is put into the sea area and sinks to the seabed under the action of the gravity of the counterweight, and magnetotelluric signal measurement is carried out.

[0060] S3: During the sinking process, the bottom-looking array 102 on the ship communicates with the underwater beacon 201 in the up-looking mode (i.e., the up-looking transducer 2011) to perform positioning and tracking during the sinking and landing processes of the instrument.

[0061] S4: After the underwater measurement is completed, the bottom-looking array 102 on the ship sends an underwater acoustic command. After receiving the command, the underwater acoustic communication module 204 starts the electro-corrosion decoupler 203. After the electro-corrosion decoupler 203 is energized for a period of time, the counterweight is released, and the seafloor magnetotelluric instrument floats up.

[0062] S5: During the floating process, the bottom-looking array 102 on the ship communicates with the underwater beacon 201 in the up-looking mode to achieve positioning and tracking during the floating process of the instrument.

[0063] S6: After the instrument reaches near the ice surface, according to the depth change judgment, the underwater beacon 201 is switched to the down-looking mode, and the underwater up-looking array 103 is deployed into the sea area to communicate with the underwater beacon 201 in the down-looking mode (i.e., the down-looking transducer 2012) to achieve underwater acoustic positioning.

[0064] S7: With the help of an icebreaker to break the ice, go to the positioning location to salvage the seafloor magnetotelluric instrument.

[0065] In the above step S6, according to the floating speed and depth, predict the time when the instrument reaches the ice surface. Because, during the floating process of this positioning method, positioning is continuously carried out. After a certain distance from the ice surface, the underwater beacon 201 in the up-looking mode is scattered by the ice surface, resulting in inaccurate positioning and unreliable data. Therefore, when no signal can be received for positioning, it can be judged that it is about to reach the ice surface, and it is switched to the down-looking mode.

[0066] At the same time, a depth sensor can also be installed in the underwater acoustic positioning system for a seafloor magnetotelluric instrument in the Arctic ice area to judge whether the instrument reaches the ice surface.

[0067] The foregoing description of specific exemplary embodiments of the present invention is for purposes of illustration and exemplification. These descriptions are not intended to limit the invention to the precise forms disclosed, and it is apparent that many modifications and variations are possible in light of the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the invention and its practical applications, so that those skilled in the art can implement and utilize the various different exemplary embodiments of the invention, as well as various different selections and modifications. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. An Arctic ice-area seabed magnetotelluric instrument hydroacoustic positioning system, comprising a shipborne device and an underwater device, wherein the shipborne device is arranged on a scientific research vessel, and the underwater device is arranged on a seabed magnetotelluric instrument; characterized in that: The shipborne equipment includes a hydroacoustic deck unit, a ship bottom down-viewing array, an underwater up-viewing array, and an underwater up-viewing beacon; the underwater equipment includes an underwater beacon capable of switching between an up-viewing mode and a down-viewing mode; The hydroacoustic deck unit is used to control the ship bottom under-view array and the underwater upper-view array to send control instructions to the underwater beacon, receive the response signal sent by the underwater beacon, and calculate the beacon position information; The ship bottom viewing array is installed at the bottom of the hull of the scientific research vessel, and can communicate with the underwater beacon in the upward viewing mode to obtain the position of the underwater equipment; The underwater upward-looking array is connected to the hull of the scientific research vessel through a cable, and can be deployed in the sea area to communicate with the underwater beacon in the downward-looking mode, thereby obtaining the position of the underwater equipment; When the underwater device is in the three stages of sinking, seabed and floating, the underwater beacon enables the upward-looking mode to acoustically communicate with the underwater downward-looking array at the bottom of the ship to realize the positioning of the underwater device; when the underwater device floats under the ice cover, it switches to the downward-looking mode and acoustically communicates with the underwater upward-looking array to realize the positioning of the underwater device.

2. The Arctic ice region seabed magnetotelluric instrument hydroacoustic positioning system according to claim 1, characterized in that: The underwater upward-looking array is deployed in the sea at a depth of 80 to 120 meters.

3. The Arctic ice region seabed magnetotelluric instrument hydroacoustic positioning system according to claim 2, characterized in that: The underwater upward-looking array is deployed in the sea at a depth of 100 meters.

4. The Arctic ice region seabed magnetotelluric instrument hydroacoustic positioning system according to claim 1, characterized in that: The underwater upward-looking beacon is also arranged on the cable connecting the underwater upward-looking array and the hull, and is used to communicate with the underwater upward-looking array at the bottom of the ship to realize the positioning of the underwater upward-looking array.

5. The Arctic ice region seabed magnetotelluric instrument hydroacoustic positioning system according to claim 4, characterized in that: The underwater upward-looking base array is arranged above the underwater upward-looking beacon and at a position close to the underwater upward-looking beacon.

6. The Arctic ice region seabed magnetotelluric instrument hydroacoustic positioning system according to claim 1, characterized in that: The underwater equipment also includes a pressure-resistant cabin, and the underwater beacon includes an upward-looking transducer and a downward-looking transducer; a hydroacoustic communication module is arranged in the pressure-resistant cabin; the hydroacoustic communication module is connected to the upward-looking transducer and the downward-looking transducer, and is used for hydroacoustic positioning and data transmission with the ship bottom downward-looking array and the underwater upward-looking array, respectively.

7. The Arctic ice region seabed magnetotelluric instrument hydroacoustic positioning system according to claim 6, characterized in that: The underwater equipment also includes an electro-corrosion decoupler arranged outside the pressure-resistant cabin; the electro-corrosion decoupler is connected to the counterweight block via a cable, and can receive instructions from the hydroacoustic communication module to fuse the cable connected to the counterweight block.

8. The Arctic ice region seabed magnetotelluric instrument hydroacoustic positioning system according to claim 6, characterized in that: The underwater equipment is also provided with a glass float.

9. A positioning method for the Arctic ice region seabed magnetotelluric instrument hydroacoustic positioning system according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1: Set the acquisition parameters of the seafloor magnetotelluric instrument and start data acquisition; S2: Place the submarine magnetotelluric instrument into the sea to measure magnetotelluric signals; S3: During the sinking process of the submarine magnetotelluric instrument, the ship's bottom-view array communicates with the underwater beacon in the upward-view mode to perform positioning and tracking during the sinking and landing process; S4: After the underwater measurement is completed, the visual array under the ship sends a command, and the hydroacoustic communication module starts the electro-corrosion decoupling device after receiving the command. After the electro-corrosion decoupling device is powered on, the counterweight is released, and the seabed magnetotelluric instrument floats up; S5: During the ascent, the down-looking array at the bottom of the ship communicates with the underwater beacon in the up-looking mode to achieve positioning and tracking of the instrument during the ascent; S6: After the instrument reaches the near ice surface, it switches the underwater beacon to the downward-looking mode according to the depth change, and deploys the underwater upward-looking array in the sea area to communicate with the underwater beacon in the downward-looking mode to achieve underwater acoustic positioning under the ice; S7: With the help of icebreakers, we go to the location to salvage the seabed magnetotelluric instruments under the ice.

10. The positioning method according to claim 9, characterized in that: In step S6, the time when the instrument will reach the ice surface is predicted based on the ascent speed and the depth of the instrument.

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