Arctic region under-ice acoustic guidance control method for AUV (Autonomous Underwater Vehicle)

Abstract

The invention relates to a north pole region under-ice acoustic guidance control method for an AUV (Autonomous Underwater Vehicle), which is used for realizing autonomous recovery of an autonomous underwater robot after the end of under-ice detection. The method includes the following steps that firstly, after an AUV ends a mission, fault information of a submersible is obtained, and small floating weights are rejected in a time-sharing mode; 2, acquiring the position of a set beacon which changes at any time in an ultra-short array coordinate system through an ultra-short positioning array carried by the AUV, and calculating the longitude and latitude of the beacon; and 3, the AUV takes the beacon longitude and latitude position as a navigation target position, and finally, the navigation target position is dynamically positioned at the beacon position within an allowable range, and waits for a remote control instruction or carries out time-sharing load rejection on the large floating weight. The method is convenient to transplant and can be suitable for various underwater robots.

Description

Technical Field

[0001] The present invention relates to the technical field of underwater robots, and in particular to an acoustic guidance control method for an AUV under ice in the Arctic region. Background Art

[0002] As the marine economy becomes a hot spot, the rich resources in the Arctic region have gradually attracted the attention of various countries, and the demand for scientific expeditions in the Arctic region is increasing. AUV has an inherent advantage in conducting scientific expeditions under the harsh climatic conditions of the Arctic region due to its technical advantages of being cable-free and unmanned. Therefore, the research on AUV has received more and more attention from various countries, and the development of AUV represents the future development direction of underwater robots. However, the process of AUV's operation under the ice in the Arctic region is complicated and the recovery is difficult. Therefore, only by designing a good operation process and recovery method can the powerful operation capability of AUV in the Arctic region be brought into play.

[0003] The AUV mission process is generally to perform comb detection according to the pre-planned tasks. After completing the exploration mission, it usually floats back to the surface by throwing loads and weights, sending radio and Iridium signals to guide the mother ship to find and recover the AUV. This method is completely fine in the normal waters where AUVs are currently used the most. However, as AUV scientific research enters the Arctic region, this normal open water is not everywhere. Instead, ice can be seen everywhere on the water, and it also conflicts with the detection mission. Therefore, when conducting scientific research in the Arctic region, only small-scale icebreaking can be carried out by scientific research ships. If the AUV is directly thrown up after the mission, because the AUV floats up in a spiral rather than vertically, it will drift under the action of the ocean current and then float below the ice surface. However, due to the obstruction of the ice layer, it is impossible to send effective position-indicating signals and communicate with the outside world. In addition, the acoustic communication device carried will not be able to communicate with the mother ship due to direction and other reasons, causing the AUV to lose contact. Therefore, Arctic scientific research requires that the AUV must be recovered to a designated three-dimensional icebreaking space area after completing the mission, waiting for instructions or performing payload recovery in this area to overcome the loss of connection caused by the floating process. In summary, it is necessary to design an under-ice acoustic guidance and control method for AUV in the Arctic region so that the AUV can be accurately recovered to the icebreaking space. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the technical problem to be solved by the present invention is to provide an acoustic guidance control method for AUV under the ice in the Arctic region. In view of the situation where the sea surface in the Arctic region is covered with a large area of ​​ice, the AUV can, after completing its mission, drop its load and float up or wait for instructions at a designated position, so as to reach the designated icebreaking position, avoid uncontrollable surfacing position and ensure the safety of the submersible.

[0005] The technical solution adopted by the present invention to achieve the above-mentioned purpose is: an acoustic guidance control method for AUV in the Arctic region, wherein an acoustic guidance control system for ice is arranged on the underwater AUV, so that it performs the following steps to achieve acoustic guidance under ice:

[0006] S1. Check faults and prepare to return: After the AUV completes its mission, it obtains its own fault information in real time and dumps small buoyancy weights in different time periods according to the fault handling method;

[0007] S2. Collect the beacon position and calculate the target longitude and latitude: The ultra-short positioning array carried by the AUV obtains the position of the beacon set by the mother ship in the ultra-short array coordinate system, which changes at any time, and calculates and converts it into the longitude and latitude of the beacon;

[0008] S3. Return and recovery: The AUV takes the beacon's longitude and latitude as the navigation target, returns to the target longitude and latitude, controls itself to be dynamically positioned at the beacon within the range allowed by the icebreaker, and waits for the mother ship's remote control command or further time-sharing dumping of large buoyancy weights.

[0009] The fault information includes: communication faults, switch faults, and water and oil leakage faults.

[0010] The fault handling method is: for an emergency fault, enter the emergency state and stop the recovery process; otherwise, dump the small floating weight in time and prepare to return.

[0011] The time-sharing load shedding is performed according to the state of the submersible.

[0012] The calculation conversion to the beacon longitude and latitude position includes:

[0013] a. Project the coordinates of the beacon in the base array motion coordinate system into the earth coordinate system to obtain the coordinates y of the beacon in the earth coordinate system with the AUV as the origin. N ,x E value:

[0014]

[0015] y N =zcosα-xsinα

[0016] x E =zsinα+xcosα

[0017] Among them, α is the heading angle of the submersible, and z, x are the coordinates collected by the beacon in the ultra-short array coordinate system.

[0018] b. Calculate the latitude and longitude of the beacon's current location (long1, lat1):

[0019] long1=long0+x E / [ARC*cos(lat0)*2π / 360]

[0020] lat1=lat0+y N / (ARC*2π / 360)

[0021] Where ARC is the average radius of the Earth.

[0022] The acoustic guidance control system for use under ice includes an ultra-short positioning array module, a computing module, a controller, and a beacon located at the icebreaker port;

[0023] The ultra-short positioning array module is used to communicate with the beacon in real time, collect the beacon position in the ultra-short positioning array coordinate system and send it to the calculation module;

[0024] The calculation module is used to convert the beacon position in the ultra-short positioning array coordinate system into beacon longitude and latitude coordinates and send them to the controller module;

[0025] The controller module is used to communicate with the mother ship and collect fault information, coordinate the modules to cooperate with each other, and control the AUV to return to the icebreaker port;

[0026] The beacon is used to provide the AUV with a return target position, from the bottom of the mother ship to the target position of the icebreaker.

[0027] The calculation module stores a program for calculating the latitude and longitude positions of the beacon.

[0028] The controller module stores a program for coordinating the modules to cooperate with each other and controlling the AUV to return and recover to the icebreaker port.

[0029] The present invention has the following advantages and beneficial effects:

[0030] 1. It is not sensitive to the model of the submersible. The controller still uses the original parameters of the submersible and can be applied to any submersible.

[0031] 2. Compared with the traditional recovery process, this method has better safety. After performing tasks under the Arctic ice, it can effectively avoid the uncertain risks brought by direct surfacing. The submersible can follow the ultra-short positioning beacon towed and dropped on the mother ship in real time, which improves the safety and timeliness of recovery, reduces the time of occupying the mother ship, and saves costs. This method is easy to transplant and can be applied to various underwater robots. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The figure is a flow chart of the method of the present invention.

[0033] Figure 2 is the position of the beacon in the ultra-short array.

[0034] Figure 3 It is the position relationship between two-dimensional coordinates and geographic coordinate system.

[0035] Figure 4 is the relationship between AUV and beacon in the geodetic coordinate system.

[0036] Figure 5 This is a flow chart for under-ice operations in the Arctic region. DETAILED DESCRIPTION

[0037] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation method of the present invention is described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the invention, so the present invention is not limited by the specific implementation disclosed below.

[0038] The present invention relates to the field of underwater robot technology, and in particular to providing an acoustic guidance control method for AUV in the Arctic region under ice, so as to realize the safe recovery of autonomous underwater robots after under ice operations in the Arctic region. The hardware requirements of the present invention are a computer, an ultra-short acoustic communication positioning integrated machine array and a beacon, which are used inside the submersible and rely on the entire control system. The method in this article is only run as a module, and a program compiled using the method is used to make real-time decisions on the current latitude and longitude, depth, speed and other control indicators of the submersible.

[0039] An acoustic guidance control method for an AUV under ice in the Arctic region comprises the following steps:

[0040] 1. After completing its mission, the AUV obtains the submersible fault information and dumps the small buoyancy weight in a time-sharing manner;

[0041] 2. The ultra-short positioning array carried by the AUV obtains the beacon position that changes at any time and sends it to the submersible control system;

[0042] 3. The AUV takes the beacon position as the navigation target position, and finally dynamically positions itself at the beacon position within the permitted range, waiting for remote control commands or time-sharing jettisoning of large buoyancy weights to surface for recovery.

[0043] Specifically:

[0044] 1. After completing its mission, the AUV obtains the submersible fault information and dumps the small buoyancy weight in time;

[0045] After the AUV completes its mission, the submersible controller needs to determine the submersible's status, analyze the submersible's fault list, and determine whether it has a "fatal" fault. It also needs to determine whether to enter an emergency state or an acoustic guidance state. When the submersible enters an emergency state, it will dump two large and small buoyancy weights to urgently float.

[0046] As long as the submersible can continue to sail, it will not enter an emergency state, otherwise it will put the submersible in a more dangerous state. When the submersible controller enters the acoustic guidance state, it outputs instructions to dump small buoyancy weights in a time-sharing manner, and obtains the position of the beacon dropped by the mother ship through the array of the ultra-short acoustic communication integrated machine carried.

[0047] Common faults of submersibles are shown in Table 1 below.

[0048] Table 1 Main roadblock types

[0049]

[0050] 2. The ultra-short positioning array carried by the AUV is used to obtain the beacon position that changes at any time, and sends it to the coordinate calculation module. According to steps 2.1-2.3, the coordinates of the beacon in the array coordinate system are converted into the longitude and latitude of the beacon.

[0051] Considering that AUV already has a relatively complete method for navigation control, this method will not be repeated here, and only the ultrashort beacon positioning and guidance method will be described, including the following steps:

[0052] After completing its mission, the submersible turns on the array of the ultra-short acoustic communication integrated device to locate and communicate with the beacon. After the mother ship places the beacon at a certain depth below the water surface, the mother ship performs dynamic positioning within a certain range and keeps the water surface within a certain range of the beacon free of ice to ensure the safety of the submersible when it is out of the water.

[0053] Define the longitude and latitude of the AUV's current position as (long0, lat0), and the position of the beacon in the ultra-short array coordinate system as (x, y, z). The relative position relationship is as follows: Figure 2 The positive direction of the Z axis of the coordinate system is consistent with the heading of the AUV.

[0054] 2.1 Convert beacon location to latitude and longitude.

[0055] a. After the ultra-short array module collects the beacon position, the coordinates of the beacon in the coordinate system of the ultra-short array are obtained as (x, y, z), where x represents the distance in the horizontal plane perpendicular to the AUV heading angle ray direction, z represents the distance along the AUV heading angle ray direction, and y represents the distance in the vertical plane perpendicular to the AUV heading angle ray direction, that is, the distance in the depth direction. The value in the depth direction can be directly added and subtracted at the current depth d0 of the AUV to obtain the target depth d1. Therefore, only the coordinates in the x and z directions need to be used to convert to the longitude and latitude directions in the two-dimensional coordinate system. The coordinate system relationship is as follows: Figure 3 shown.

[0056] b. The coordinate calculation module executes the following two formulas in sequence to obtain the longitude and latitude coordinates of the beacon.

[0057] Project the coordinates of the beacon in the array (AUV) motion coordinate system into the earth coordinate system. Solve the conversion formula (1)

[0058]

[0059] Among them, α is the heading angle of the submersible, z, x are the coordinates of the beacon in the ultra-short array (i.e. AUV) coordinate system, y N ,x E is the coordinate of the beacon in the geodetic coordinate system with the AUV as the origin.

[0060] Then, the position relationship between the AUV and the beacon in the geodetic coordinate system is as follows: Figure 4 shown.

[0061] According to formula (2), the longitude and latitude of the current location of the beacon (long1, lat1) can be obtained, where ARC is the average radius of the earth.

[0062]

[0063] 2.2 Update location information.

[0064] When performing acoustic positioning underwater, the ultra-short array may be unable to locate the beacon due to the relative position relationship and the influence of factors such as the ocean environment. Therefore, the positioning situation needs to be updated.

[0065] Define a as a counter of effective positioning information obtained by the ultra-short array module. After the ultra-short array obtains effective positioning information of the beacon, a=a+1.

[0066] Define b as the counter of the beacon positioning information received by the submarine coordinate calculation module through the serial port from the ultra-short array module. After the submarine coordinate calculation module obtains the valid beacon positioning information, b=b+1.

[0067] The data structure sent by the ultra-short array module to the submersible coordinate calculation module is defined as {t, (x, y, z), a}, where t is the time when the positioning information is obtained, (x, y, z) is the coordinate of the beacon in the ultra-short array coordinate system, and a is the counter of the effective positioning information obtained by the ultra-short array module. When b < a, the submersible coordinate calculation module updates the coordinates of the beacon and solves the longitude and latitude of the beacon through formula (1) and formula (2).

[0068] 2.3 Issue control instructions.

[0069] The submersible coordinate calculation module sends the latitude, longitude and depth of the beacon as target position parameters to the submersible controller, which controls the submersible until it reaches the beacon position.

[0070] The command sent is GALS_XY(long,lat,v,d,mode), where long is the beacon longitude, lat is the beacon latitude, v is the submersible's navigation speed, d is the beacon depth, and mode is the navigation mode (fixed altitude / fixed depth).

[0071] 3. The AUV takes the beacon position as the navigation target position, and finally dynamically positions itself at the beacon position within the permitted range, waiting for remote control instructions.

[0072] Since there are relatively mature control methods for submersibles in fixed-point navigation, this article will not discuss them.

[0073] When the submersible reaches within the radius D (100 meters based on experience) of the beacon position, it will carry out dynamic positioning, maintain the depth, longitude and latitude of the submersible, and accept remote control instructions within 10 minutes of maintaining dynamic positioning to perform the next specified action. If no new remote control instructions from the acoustic communication machine are received after 10 minutes, the large buoyancy weights will be dropped in time, and the submersible will float to the surface and wait for recovery by the mother ship.

[0074] The specific process is as follows:

[0075] Depending on the health status of the submersible after completing the planned mission, it is determined whether to enter an emergency state or an acoustic guidance state.

[0076] When the submersible enters an emergency state, it dumps two large and small buoyancy weights to achieve emergency buoyancy.

[0077] When the submersible enters the acoustic guidance state, it will jettison small buoyancy weights in a time-sharing manner and obtain the position of the beacon lowered by the mother ship through the array of the ultra-short acoustic communication integrated device it carries.

[0078] Convert the coordinates of the beacon in the base array coordinate system to the longitude and latitude of the beacon according to steps 2.1-2.3.

[0079] The beacon's latitude and longitude, depth, and required submersible speed and navigation mode (fixed altitude / fixed depth) are sent to the submersible control system. The submersible autonomously plans and controls its navigation path to the target point based on its current position.

[0080] When it reaches a certain range of the beacon, it will perform dynamic positioning, report the situation to the mother ship and wait for remote control instructions. If there is no new remote control instruction after a period of time, it will drop the large buoyancy weight in time, float to the surface and wait for the mother ship to recover it.

[0081] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent structural change made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. An acoustic guidance control method for an AUV under ice in the Arctic region, characterized in that: An acoustic guidance control system for under-ice is set on the underwater AUV to perform the following steps to achieve under-ice acoustic guidance: S1. Check faults and prepare to return: After the AUV completes its mission, it obtains its own fault information in real time and dumps small buoyancy weights in different time periods according to the fault handling method; S2. Collect the beacon position and calculate the target longitude and latitude: The ultra-short positioning array carried by the AUV obtains the position of the beacon set by the mother ship in the ultra-short array coordinate system, which changes at any time, and calculates and converts it into the longitude and latitude of the beacon; S3. Return and recovery: The AUV takes the beacon's longitude and latitude as the navigation target, returns to the target longitude and latitude, controls itself to be dynamically positioned at the beacon within the range allowed by the icebreaker, and waits for the mother ship's remote control command or further time-sharing dumping of large buoyancy weights.

2. The method for acoustic guidance and control of an AUV under ice in the Arctic region according to claim 1, characterized in that: The fault information includes: communication faults, switch faults, and water and oil leakage faults.

3. The method for acoustic guidance and control of an AUV under ice in the Arctic region according to claim 1, characterized in that: The fault handling method is: for an emergency fault, enter the emergency state and stop the recovery process; otherwise, dump the small floating weight in time and prepare to return.

4. The method for acoustic guidance and control of an AUV under ice in the Arctic region according to claim 1, characterized in that: The time-sharing load shedding is performed according to the state of the submersible.

5. The method for acoustic guidance and control of an AUV under ice in the Arctic region according to claim 1, characterized in that: The calculation conversion to the beacon longitude and latitude position includes: a. Project the coordinates of the beacon in the base array motion coordinate system into the earth coordinate system to obtain the coordinates y of the beacon in the earth coordinate system with the AUV as the origin. N ,x E value: and N =zcosα-xsinα x E =z sinα+x cosα Among them, α is the heading angle of the submersible, and z, x are the coordinates collected by the beacon in the ultra-short array coordinate system. b. Calculate the latitude and longitude of the beacon's current location (long1, lat1): long1=long0+x E / [ARC*cos(lat0)*2π / 360] lat1=lat0+y N / (ARC*2π / 360) Where ARC is the average radius of the Earth.

6. The method for acoustic guidance and control of an AUV under ice in the Arctic region according to claim 1, characterized in that: The acoustic guidance control system for use under ice includes an ultra-short positioning array module, a computing module, a controller, and a beacon located at the icebreaker port; The ultra-short positioning array module is used to communicate with the beacon in real time, collect the beacon position in the ultra-short positioning array coordinate system and send it to the calculation module; The calculation module is used to convert the beacon position in the ultra-short positioning array coordinate system into beacon longitude and latitude coordinates and send them to the controller module; The controller module is used to communicate with the mother ship and collect fault information, coordinate the modules to cooperate with each other, and control the AUV to return to the icebreaker port; The beacon is used to provide the AUV with a return target position, from the bottom of the mother ship to the target position of the icebreaker.

7. The method for acoustic guidance and control of an AUV under ice in the Arctic region according to claim 6, characterized in that: The calculation module stores a program for calculating the latitude and longitude positions of the beacon.

8. The method for acoustic guidance and control of an AUV under ice in the Arctic region according to claim 6, characterized in that: The controller module stores a program for coordinating the modules to cooperate with each other and controlling the AUV to return and recover to the icebreaker port.

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