An AIS-based group ship collision avoidance route automatic planning method and system

Abstract

The present application relates to the field of marine automation and information technology, in particular to a group ship collision avoidance route automatic planning method, system and device based on AIS. The method comprises data acquisition and analysis; collision danger point calculation and statistics of route; turning starting point calculation; heuristic method heading angle calculation; regression point calculation; regression drop point calculation and new route determination. The system comprises AIS data acquisition and analysis module, collision danger point calculation and statistics module of route, turning starting point calculation module, turning angle calculation module, regression point calculation module, regression drop point calculation module and new route determination module. The method and system can solve the problems of route automatic generation and timeliness deficiency, accuracy deficiency in existing route planning technology, and promote the development of shipping industry to a more efficient, safe and environmentally friendly direction.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of marine automation and information, and particularly relates to a group ship collision avoidance route automatic planning method and system based on AIS. BACKGROUND

[0002] In the global trade and economic boom, the shipping industry as the artery of the world economy, continues to show its indispensable importance. With the continuous injection of capital and rapid technological innovation, shipping companies are accelerating the modernization of the fleet, by building efficient new ships and upgrading existing fleets, significantly improving the carrying capacity and operational efficiency of ships. In particular, the deep integration of automation and intelligent technology has brought unprecedented safety performance improvement and transportation efficiency leap for the shipping industry, further consolidating its core position in the global trade system.

[0003] However, the current ship route planning field still faces many challenges. The traditional planning method based on preset waypoints, although to some extent, meets the basic navigation needs, but in the face of complex and variable marine environment, dynamic traffic conditions and sudden maritime events, its flexibility and adaptability are particularly insufficient. Coupled with the subjectivity of manual operation and the limitations of simple calculation methods, it is difficult to ensure the high precision and efficiency of route planning, especially in the current situation of traffic surge and route congestion, which has intensified the risk of navigation and cost burden.

[0004] Under this background, ship route planning, as the core link of the shipping industry, is self-evident. It is not only the cornerstone of ensuring ship navigation safety, optimizing transportation costs and promoting environmental friendliness, but also an important indicator of the competitiveness and intelligent level of shipping enterprises. Formulating a route that meets the safety specifications and maximizes transportation efficiency and economic benefits is the primary prerequisite for the successful completion of the ship's voyage. Especially in today's rapidly changing technology, realizing the automatic planning and intelligent adjustment of ship routes has a milestone significance for the development of unmanned ship navigation technology.

[0005] However, the current ship route planning field still faces many challenges. The traditional planning method based on preset waypoints, although to some extent, meets the basic navigation needs, but in the face of complex and variable marine environment, dynamic adjustment of traffic conditions and sudden maritime events, its flexibility and adaptability are particularly insufficient. Coupled with the subjectivity of manual operation and the limitations of simple calculation methods, it is difficult to ensure the high precision and high efficiency of route planning, especially in the current situation of traffic surge and route congestion, which has intensified the risk of navigation and cost burden. Although in recent years, the academic and industrial circles have proposed various automatic route generation methods based on electronic charts, ant colony algorithm, shortest time of water depth, etc., but these researches are mostly at the stage of theoretical exploration and laboratory verification, and their reliability, real-time performance and wide applicability in practical application still need to be fully verified and optimized. Especially for long-distance, cross-sea complex routes, the existing methods are difficult to meet the urgent needs of instant generation and accurate navigation, which limits the improvement of the overall intelligent level of the shipping industry. SUMMARY

[0006] The present application solves the problem of insufficient timeliness and accuracy of existing route planning methods for long-distance, cross-sea complex routes, and proposes an automatic route planning method and system for group ship collision avoidance based on AIS.

[0007] The technical solution claimed in the present application is as follows:

[0008] An automatic route planning method for group ship collision avoidance based on AIS, comprising the following steps:

[0009] S1: AIS data acquisition and analysis: acquiring AIS raw message data of ships at sea, and analyzing the AIS raw message data to obtain ship AIS data;

[0010] S2: Collision danger point calculation and statistics: based on the ship AIS data obtained in S1, taking the current time as the reference and a preset time period as the time interval, calculating a plurality of time points in the future period of time, and calculating the corresponding position point distance between the own ship and other ships at the plurality of time points according to the plurality of time points, and according to the corresponding position point distance, calculating the collision danger points between the own ship and other ships, and constructing a collision danger point set;

[0011] S3: Calculation of turning start point: selecting the nearest collision danger point from the collision danger point set constructed in S2, and calculating the turning start point according to the corresponding position point distance between the nearest collision danger point and the current position of the own ship;

[0012] S4: Trial steering angle calculation: determine the heading angle adjustment range, use the trial method to perform step-by-step trial calculation at the steering starting point described in S3, according to the heading angle adjustment range, increase the heading angle from small to large according to a specific step length, execute S2 step until a smooth passing angle is found for the ship in the future period of time, and according to the turning angle, perform turning;

[0013] S5: Regression point calculation: determine the appropriate regression point range after turning in S4, sequentially perform the regression process for the points in the regression point range, and calculate until a point that can avoid all other ships and safely return to the original channel is found, which is the regression point;

[0014] S6: Regression landing point calculation: determine the landing point of the ship returning to the original channel according to the regression point confirmed in S5;

[0015] S7: New route determination: determine the new route of the ship by connecting five points according to the current position of the ship, the steering starting point calculated in S3, the regression point calculated in S5, the regression landing point calculated in S6, and the farthest point of the route planning.

[0016] Preferably, the ship in S1 is equipped with an automatic identification system, and the specific process of AIS data acquisition and analysis is as follows: an AIS isolator distributor connected to the shipboard automatic identification system is installed on the ship, and a serial server, a switch and an analysis server are connected in turn; the shipboard automatic identification system is responsible for receiving all types of AIS broadcast signals of all ships within the effective range around the ship, and provides an external interface, through the AIS isolator distributor, synchronously and in parallel outputs a signal to the serial server, and the serial server converts the serial format AIS broadcast signal into a network signal and then inputs it into the switch, and then the network signal is input into the analysis server for decoding and analysis to obtain ship AIS data.

[0017] Preferably, the AIS raw message data is transmitted using compressed ASCII code, complies with NMEA0183 protocol, and is divided into clear text and cipher text; therefore, the decoding and analysis of the network signal by the analysis server is to analyze the A and B type messages starting with "!AIVDM", and extract ship position information, navigation dynamics and static parameters therefrom; the navigation dynamics and static parameters include MMSI, ship name, heading and speed.

[0018] Preferably, the preset time period in S2 is 10 seconds, and the future period of time is 6 hours; the future period of time in S4 is 1 hour.

[0019] Preferably, S2 specifically includes the following steps:

[0020] S21: The ship and the other ship time synchronization: with the current time as the reference point, the preset time period as the time interval, calculate a plurality of time points in the future period of time, and calculate the time difference between the plurality of time points and the time in the latest AIS data of the ship and the other ship, the plurality of time points are time synchronization points; the relationship between the i th time synchronization point and the time in the latest AIS data of the ship and the other ship is calculated according to the following formula:

[0021]

[0022] Wherein: T self (i) represents the time difference between the i th time synchronization point and the time in the latest AIS data of the ship; t self0 represents the time in the latest AIS data of the ship; T other (i) represents the time difference between the i th time synchronization point and the time in the latest AIS data of the other ship; t other0 represents the time in the latest AIS data of the other ship; t represents the current time;

[0023] S22: The ship and the other ship future time position synchronization: on the basis of time synchronization in S21, assuming that all ships remain unchanged, according to the current time S1 step, the latest ship AIS data is collected to calculate the longitude and latitude coordinates of the ship and the other ship corresponding to the plurality of time synchronization points in S21 according to the heading angle, the speed, the longitude and latitude coordinates;

[0024] The ship longitude and latitude coordinate calculation formula is as follows:

[0025]

[0026] Wherein: (lon selfi , lat selfi ) represents the longitude and latitude coordinates of the i th time synchronization point of the ship; T self (i) represents the time difference between the i th time synchronization point and the time in the latest AIS data of the ship; (lon self0 , lat self0 ), sog self , cog self respectively represent the longitude and latitude coordinates, the speed, the heading angle of the position in the latest AIS data of the ship; R represents the earth radius;

[0027] The other ship longitude and latitude coordinate calculation formula is as follows:

[0028]

[0029] Wherein: (lon otheri , lat otheri ) represents the longitude and latitude coordinates of the i th time synchronization point of the other ship; T other(i) represents the time difference between the i th time synchronization point and the time in the latest AIS data of the other ship; (lon other0 , lat other0 ) represent the longitude and latitude coordinates of the position in the latest AIS data of the other ship, respectively; sog other , cog other represent the speed and the heading angle, respectively; and R represents the radius of the earth;

[0030] S23: Corresponding position point distance calculation: the distances between the ship and the other ship at the corresponding position points corresponding to the plurality of time synchronization points are calculated using the longitude and latitude coordinates of the ship and the other ship described in S22, to obtain a plurality of corresponding position point distances between the ship and the other ship; the corresponding position point distance calculation formula is as follows:

[0031] d i = R x acos(sin(lon selfi ) x sin(lon otheri )

[0032] + cos(lon selfi ) x cos(lon otheri ) x cos(lat otheri - lat selfi ))

[0033] wherein (lon selfi , lat selfi ) and (lon otheri , lat otheri ) represent the longitude and latitude coordinates of the i th time synchronization point of the ship and the other ship, respectively; and R is the radius of the earth;

[0034] S24: Collision risk point calculation and statistics: the minimum safety distance is determined based on the rules for ship collision avoidance at sea, and if the corresponding position point distance in S23 is less than the minimum safety distance, it is determined that the other ship has a collision risk with the ship, and the time and position when the collision risk occurs are recorded, and the number of collision risks is counted, and the calculation formula is as follows:

[0035]

[0036] wherein n represents the number of all time synchronization points in the future time; d T represents the minimum safety distance of the ship; d i represents the corresponding position point distance between the ship and the other ship at the i th time synchronization point; N represents the number of time synchronization points in which the corresponding position point distance is less than the minimum safety distance of the ship; and A represents the set of corresponding position point distances less than the minimum safety distance, i.e., the collision risk point set, which includes the time, position and corresponding position point distance corresponding to each collision risk point in the set.

[0037] Preferably, S3 comprises the following steps:

[0038] S31: determining the nearest collision danger point: the nearest collision danger point is the first point in the set of collision danger points of the own ship, i.e. the point with the smallest time;

[0039] S32: calculating the turning start point: the time, position, speed, and heading angle in the latest AIS data of the own ship are brought into the formulae described in S21-S22 to calculate the latitude and longitude coordinates of the current position of the own ship; the latitude and longitude coordinates of the current position of the own ship and the nearest collision danger point are brought into the formula described in S23 to calculate the corresponding position point distance between the own ship and the nearest collision danger point; if the corresponding position point distance between the current position of the own ship and the nearest collision danger point is less than or equal to 3 nautical miles, the current position of the own ship is the turning start point of the current route planning; otherwise, the own ship continues to sail along the original route, and when the distance to the nearest collision danger point is less than or equal to 3 nautical miles, the heading is adjusted, and the point at which the adjustment of the heading starts is the turning start point.

[0040] Preferably, S4 comprises the following steps:

[0041] S41: determining the heading angle adjustment range: the heading angle adjustment range and the step length are set according to relevant requirements and rules, the exploratory route exploration is performed starting from 15° with a step length of 5°, and the maximum adjustment angle is set to 60° deflection angle;

[0042] S42: stepwise exploratory calculation: the stepwise route exploration is performed using the exploratory method starting from the minimum heading angle of the heading angle adjustment range; the steps S21-S24 are performed on the own ship sailing along a specific heading angle to calculate and count the collision danger points of the own ship and other ships, and whether the smooth navigation condition of the own ship in the detour phase is met is determined according to the number of collision danger points; the smooth navigation condition is that the own ship has no collision risk with other ships on the new route within the next 1 hour after the heading is adjusted at the turning start point; the detour phase is the phase in which the own ship sails along a specific heading angle;

[0043] S43: determining the smooth detour angle: if the smooth navigation condition is met, the specific heading angle is the turning angle at which the own ship can smoothly navigate in the detour phase; if the smooth navigation condition is not met, the step S42 is continued until a turning angle at which the own ship can smoothly navigate in the detour phase is found.

[0044] Preferably, S5 comprises the following steps:

[0045] S51: determining the reversion point range: the route reversion is performed between the half hour to 1 hour after the start of the detour phase, and the reversion point is selected within the determined reversion point range, and the formula is as follows:

[0046]

[0047] wherein: p mis the first time synchronization point in the range of the return point; p n is the last time synchronization point in the range of the return point; p x is the assumed return point, the assumed return point p x is sequentially taken between p m and p n ;

[0048] S52: Collision avoidance calculation in the return process: assuming A e is the farthest point in the original channel collision risk point set, i.e. the last collision risk point; assuming that the ship attempts to return from the assumed return point p x to the first time synchronization point position 3 nautical miles after the farthest collision risk point A e , the ship's return course angle cog s ; elf The calculation formula is as follows:

[0049]

[0050] Where: (lon px , lat px ) is the longitude and latitude coordinates of the assumed return point p x ; (lon ae+3 , lat ae+3 ) is the longitude and latitude coordinates of the first time synchronization point 3 nautical miles after the farthest collision risk point A e , i.e. the assumed return point p x ; taking the assumed return point p s as the new reference point of the ship, cog elf ; x is the new course angle of the ship, performing S21-S24 calculation and counting the collision risk points of the ship and other ships, so as to determine whether the ship has collision risk with other ships in the return process;

[0051] S53: Determine the return point: the return point is confirmed by a bidirectional stepping method, as follows: assuming that there is no collision risk in the return process of performing S52, p e is determined as the return point; if there is a collision risk in the return process, the second time synchronization point 3 nautical miles outside A e is selected to return, and S21-S24 is repeatedly performed to determine whether the ship has collision risk with other ships in the return process; by analogy, assuming that there are m time synchronization points between 3 nautical miles outside A x and the farthest point on the planned route on the original channel, the ship attempts to return from p x to the positions corresponding to the m time synchronization points, until a collision-free route is found; if not, p x+1, repeat the above process, calculate p x+1 Regression route to the original channel m time synchronization points to determine p x+1 Whether to meet the regression condition; in this way, until the final regression point is found to meet the condition.

[0052] Preferably, the regression landing point in S6 is the point where the collision-free route found in S52-S53 intersects the original route, i.e. the regression landing point.

[0053] The application also provides an AIS-based group ship collision avoidance route automatic planning system, comprising an AIS data acquisition and analysis module connected in sequence for acquiring AIS original message data of a ship under navigation and analyzing the same to obtain ship AIS data, a route collision danger point calculation and statistics module for calculating and statistics collision danger points of the ship and other ships and constructing a collision danger point set according to the ship AIS data acquired by the AIS data acquisition and analysis module, a turning start point calculation module for calculating a turning start point according to the distance between the nearest collision danger point and the corresponding position point of the current position of the ship, a turning angle calculation module for finding a turning angle that can meet the smooth navigation condition within the heading angle adjustment range by using the trial method, a regression point calculation module for calculating a regression point within the regression point range by using the bidirectional stepping method, a regression landing point calculation module for determining the landing point of the ship returning to the original channel according to the regression point, and a new route determination module for connecting the current position of the ship, the turning start point, the regression point, the regression landing point and the route planning farthest point to obtain a new route of the ship.

[0054] The route collision danger point calculation and statistics module calculates a plurality of time points in the future period of time according to the ship AIS data acquired by the AIS data acquisition and analysis module with the current time as the reference and a preset time period as the time interval, calculates the corresponding position point distances of the ship and other ships at the plurality of time points, and statistics collision danger points of the ship and other ships according to the corresponding position point distances to construct a collision danger point set.

[0055] The turning angle calculation module determines the heading angle adjustment range, and the turning start point calculated by the turning start point calculation module is calculated by using the trial method in a step-by-step trial manner, the heading angle is increased according to a specific stepping length from small to large according to the heading angle adjustment range, and the route collision danger point calculation and statistics module is used for collision danger point statistics until a turning angle that can meet the smooth navigation of the ship in the future period of time is found, and the ship is turned according to the turning angle; the smooth navigation refers to that the number of collision danger points is 0.

[0056] The regression point calculation module determines a suitable regression point range after the trial steering angle calculation module determines to make a detour, and performs collision avoidance calculation on points in the regression point range in turn, and calculates by using a bidirectional stepping method until a point that can avoid all other ships and safely return to the original navigation channel is found, that is, the regression point.

[0057] Beneficial effects:

[0058] The application provides an AIS-based group ship collision avoidance route automatic planning method and system, and the method comprises the following steps: acquiring AIS original message data of a ship under navigation and analyzing the AIS original message data to obtain ship AIS data; by acquiring the AIS original message data of the ship under navigation and analyzing the AIS original message data, key information of the ship under navigation can be acquired in real time, and accurate capture of dynamic changes of the ship is realized; latest AIS data acquired according to a current time is used to calculate collision risk points between the ship and other ships in a future period of time when the ship is sailing on a current channel, and the collision risk points are counted; a route is adjusted in real time according to the counted collision risk points, the problem of inaccurate route planning caused by information lag is effectively avoided, and the timeliness and accuracy of route planning are significantly improved; the latitude and longitude coordinates of the nearest collision risk point are acquired, the latitude and longitude coordinates of the position of the ship are calculated, and the distance between the corresponding position points (that is, the mutual distance between the position point of the ship and the collision risk point) is calculated; the mutual distance is used to determine a turning starting point; after the turning starting point is determined, a heading angle adjustment range is determined, a trial method is used to determine a turning angle in the heading angle adjustment range, and a suitable turning angle is determined to make the ship sail smoothly in a detour stage; after the ship makes a detour, a suitable regression point range is determined, collision avoidance calculation in a regression process is performed on points in the regression point range, and a bidirectional stepping method is used to calculate until a point that can avoid all other ships and safely return to the original navigation channel is found, that is, a safe regression route with 0 collision risk points is found, so that the regression point is determined; the two advanced algorithms of the trial method and the bidirectional stepping method can flexibly adjust the heading angle and the regression point, and ensure that the ship meets the condition of smooth sailing in the detour stage and the regression stage, the dynamic adjustment mechanism makes the route planning more flexible and variable, and better adapts to various sudden situations in actual navigation, and reduces the navigation risk; the determined regression point is used to determine a landing point of the ship returning to the original navigation channel; the optimized route can reduce unnecessary detours and waiting time, reduce fuel consumption and operation cost, and thus improve the economic benefit of a shipping enterprise; finally, a new route is obtained by connecting the current position of the ship, the turning starting point, the regression point, the regression landing point and the farthest point of the route planning; by integrating the AIS data and the advanced algorithms, the problem of insufficient timeliness and lack of accuracy of route automatic generation existing in the existing route planning method for complex routes of long distances and across sea areas is solved, the automation and intelligentization of route planning are realized, and a solid foundation is laid for the development of unmanned ship navigation technology, which not only helps to improve the overall competitiveness of the shipping industry, but also promotes the entire industry to develop in a more efficient, safe and environmentally friendly direction.

[0059] According to the longitude and latitude, the speed, the direction and the time synchronization relationship in the AIS data of all ships in the effective range around the latest in-service ship obtained by the current ship, the future ship position is time-synchronized at a time interval of 10 seconds, the mutual distance between the current ship and all surrounding ships (other ships) is calculated in real time, and whether the current ship and the other ships have collision risks is determined according to the distance size, and the real-time performance is high.

[0060] A safe return route with a collision risk point of 0 is found by using a bidirectional stepping method between the farthest collision risk point of the original route and the farthest point of the current route planning, and then the return landing point of the current route planning is determined, the collision risk free route is planned by accurately calculating the collision risk point, and the reasonable safety distance is set according to the requirements of early giving and wide giving, so that the incidence of collision accidents of multiple ships and group ships can be effectively reduced, and the navigation safety can be significantly improved.

[0061] The present application takes the maritime navigation collision avoidance rule and the crew's sailing habit as the theoretical basis for design, strictly according to the requirements of early giving and wide giving, ensures a safety distance of at least 3 nautical miles; at the same time, the present application adopts a 6-hour long route planning algorithm, which can avoid collision of multiple ships and group ships. The ship route planning should take the destination port as the benchmark, combined with the original ship route design, to achieve safety and efficiency. The principle of the route planning method of the present application is safe detouring and timely returning. Under the premise of safe detouring of the ship, the ship's yaw, returning and improving energy efficiency are also considered, which has higher practicability. BRIEF DESCRIPTION OF DRAWINGS

[0062] Figure 1 The figure is a flow chart of the AIS-based group ship collision avoidance route automatic planning method of the embodiment of the present application.

[0063] Figure 2 The figure is a connection schematic diagram of the shipborne AIS device and other auxiliary equipment of the embodiment of the present application.

[0064] Figure 3 The figure is a schematic diagram of the AIS-based group ship collision avoidance route automatic planning system of the embodiment of the present application. DETAILED DESCRIPTION

[0065] In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme will be further clearly and completely described below in combination with the drawings of the present application.

[0066] The first group of embodiments provides an AIS-based group ship collision avoidance route automatic planning method.

[0067] The group of embodiments provides an AIS-based group ship collision avoidance route automatic planning method, as shown in the figure, including the following steps: Figure 1

[0068] ​S1: AIS Data Acquisition and Parsing: Acquire the raw AIS message data of the vessel underway, and parse the raw AIS message data to obtain the vessel's AIS data (AIS data of the vessel underway and all vessels within its effective range); the vessel's AIS data includes speed, heading angle, time, and position; the position includes longitude and latitude coordinates; all vessels within the effective range of the vessel underway are other vessels; the vessel underway is this vessel;

[0069] The vessel is equipped with an onboard Automatic Identification System (AIS signal system), and the AIS data acquisition and parsing are performed using auxiliary equipment installed on the onboard equipment. Figure 2 The implementation involves installing an AIS isolation distributor connected to the shipborne Automatic Identification System (AIS) on the ship, and sequentially connecting it to a serial port server, a switch, and an analysis server. The shipborne AIS is responsible for receiving various AIS broadcast signals from all ships within its effective range and providing an external interface. Through the AIS isolation distributor, it synchronously and in parallel outputs one signal to the serial port server. The serial port server converts the serial-formatted AIS broadcast signal into a network signal, which is then connected to the switch. Finally, the network signal is connected to the analysis server for decoding and parsing to obtain AIS data.

[0070] The raw AIS message data is obtained from the ship's onboard AIS signal receiver, transmitted using compressed ASCII code, and conforms to the NMEA0183 protocol, consisting of plaintext and ciphertext messages. Therefore, the analysis server decodes and parses the network signals by parsing Class A and B messages beginning with "!AIVDM" to extract ship position information, dynamic and static navigation parameters. These dynamic and static parameters include MMSI (Maritime Mobile Service Identifier), ship name, heading, and speed. The functional relationships of the parsing process are described below:

[0071]

[0072] Among them, the AIS raw message data is used as an input parameter, and its format is as follows:

[0073] "!AIVDO,1,1,,,16:5eEP0@mWp=of;NR;8qoCR3P00,0*5B"

[0074] NMEA183(AIS) indicates that the raw AIS message data is parsed according to the NMEA183 protocol; the output of the above parsing process function is the ship navigation-related parameters, including: ship identification code MMSI (mmsi), speed (sog), heading angle (cog), longitude (lon), and latitude (lat).

[0075] S2: Collision risk point calculation and statistics: According to the ship AIS data obtained in S1, taking the current time as the reference point and the preset time period as the time interval, a plurality of time points in the future time period are calculated, and the corresponding position point distances of the ship and the other ship at the plurality of time points are calculated according to the plurality of time points, and the collision risk points of the ship and the other ship are calculated according to the corresponding position point distances, and a collision risk point set is constructed; in a specific embodiment of the present application, the preset time period is 10 seconds, and the future time period is 6 hours;

[0076] S2 specifically includes the following steps:

[0077] S21: Ship and other ship time synchronization: taking the current time as the reference point and the preset time period as the time interval, a plurality of time points in the future time period are calculated, and the time difference between the plurality of time points and the time in the latest AIS data of the ship and the other ship is calculated, the plurality of time points are called time synchronization points; in a specific embodiment of the present application, taking the current time as the reference point and 10 seconds as the time interval, a plurality of time points in the future 6 hours are calculated, and the time difference between the plurality of time points in the future 6 hours and the time in the latest AIS data of the ship and the other ship is calculated; the relationship between the i th time synchronization point of the ship and the other ship and the time in the corresponding latest AIS data is calculated according to the following formula:

[0078]

[0079] Wherein: T self (i) represents the time difference between the i th time synchronization point and the time in the latest AIS data of the ship; t represents the current time; t self0 represents the time in the latest AIS data of the ship; T other (i) represents the time difference between the i th time synchronization point and the time in the latest AIS data of the other ship; t other0 represents the time in the latest AIS data of the other ship; t represents the current time;

[0080] S22: Ship and other ship future time position synchronization: on the basis of time synchronization in S21, assuming that all ships remain unchanged, the heading angle, speed, latitude and longitude coordinates in the latest ship AIS data collected in S1 according to the current time are calculated to obtain the latitude and longitude coordinates of the ship and the other ship corresponding to the plurality of time synchronization points in S21; in a specific embodiment of the present application, according to the geographical knowledge, the calculation formula of the latitude and longitude coordinates of the i th time synchronization point of the ship is as follows:

[0081]

[0082] Wherein: (lon selfi , lat selfirepresents the i-th time synchronization point ship longitude and latitude coordinates; T self (i) represents the i-th time synchronization point and the latest AIS data of the ship time difference in time; (lon self0 , lat self0 ), sog self , cog self respectively represent the latest AIS data of the ship position of the longitude and latitude coordinates, speed, heading angle; R represents the earth radius, about 6371 kilometers;

[0083] According to the knowledge of geography, the i-th time synchronization point of the other ship longitude and latitude coordinates calculation formula is as follows:

[0084]

[0085] Among them: (lon otheri , lat otheri ) represents the i-th time synchronization point of the other ship longitude and latitude coordinates; T other (i) represents the i-th time synchronization point and the latest AIS data of the other ship time difference in time; (lon other0 , lat other0 ), sog other , cog other respectively represent the latest AIS data of the other ship position of the longitude and latitude coordinates, speed, heading angle; R represents the earth radius, about 6371 kilometers;

[0086] S23: corresponding position point distance calculation: using the ship and the other ship longitude and latitude coordinates described in S22 to calculate the corresponding distance between the ship and the other ship at multiple time synchronization points, obtain multiple corresponding position point distances between the ship and the other ship; In the specific embodiments of the present application, based on spherical trigonometry, the corresponding position point distance formula between the ship and the other ship is as follows:

[0087] d i =R×acos(sin(lon selfi )×sin(lon otheri )+

[0088] cos(lon selfi )×cos(lon otheri )×cos(lat otheri -lat selfi ))

[0089] Among them: d i represents the corresponding position point distance between the ship and the other ship at the i-th time synchronization point (mutual distance); R represents the earth radius, about 6371 kilometers; (lon selfi , lat selfi ), (lonotheri , lat otheri ) represent the longitude and latitude coordinates of the i-th time synchronization point of the own ship and the other ship, respectively;

[0090] S24: Collision risk point calculation and statistics: determine the minimum safety distance based on the rules of ship collision at sea, and determine that the other ship has a collision risk with the own ship if the distance between the corresponding position points in S23 is less than the minimum safety distance, and record the time, position, and number of collision risks, and calculate the formula as follows:

[0091]

[0092] Wherein: n represents the number of all time synchronization points within the future time (6 hours); d T represents the minimum safety distance of the ship; d i represents the distance between the i-th time synchronization point of the own ship and the corresponding position point of the other ship; N represents the number of time synchronization points whose corresponding position point distance is less than the minimum safety distance of the ship; A represents the set of corresponding position points whose distance is less than the minimum safety distance, that is, the collision risk point set, which includes the time, position and corresponding position point distance corresponding to each collision risk point in the set.

[0093] S3: Turning start point calculation: select the nearest collision risk point from the collision risk point set constructed in S2, and calculate the turning start point according to the corresponding position point distance between the nearest collision risk point and the current position of the own ship; Specifically, the following steps are included:

[0094] S31: Determine the nearest collision risk point: the nearest collision risk point is the first point in the collision risk point set of the own ship, that is, the point with the smallest time; In the specific embodiment of the present application, it is assumed that the point A0 with the smallest time in the collision risk point set A described in S24 is the nearest collision risk point; The calculation of the turning start point is a process of determining the most appropriate time for the own ship to adjust the heading between the current position and A0 after determining the nearest collision point A0;

[0095] S32: Turning start point calculation: bring the time, position, speed, heading angle in the latest AIS data of the own ship into the formula described in S21-S22 to calculate the longitude and latitude coordinates of the current position of the own ship; Bring the longitude and latitude coordinates of the current position of the own ship and the nearest collision risk point into the formula described in S23 to calculate the corresponding position point distance (mutual distance) between the own ship and the nearest collision risk point; If the mutual distance between the current position of the own ship and the nearest collision risk point is less than or equal to 3 nautical miles, then the current position of the own ship is the turning start point of this voyage planning; Otherwise, the own ship continues to sail along the original route, and when the distance to the nearest collision risk point is less than or equal to 3 nautical miles, the point of adjusting the heading is the turning start point. In the specific embodiment of the present application, the calculation formula of the longitude and latitude coordinates of the current position of the own ship is as follows:

[0096]

[0097] wherein: (lon self_1 , lat self_1 ) represents the longitude and latitude coordinates of the current time of the ship; (lon self0 , lat self0 ), sog self , cog self respectively represent the longitude and latitude coordinates of the position, the speed, and the heading angle of the latest AIS data of the ship; R represents the radius of the earth, about 6371 kilometers; and t represents the current time;

[0098] Further, the longitude and latitude coordinates of the current position of the ship and the longitude and latitude coordinates of the nearest collision danger point are brought into the formula S23 to calculate the corresponding position point distance d 0_1 between the current position point (the running position of the current ship) of the ship and the nearest collision danger point;

[0099] The sea collision avoidance rule requires that ships meet early and wide, but considering the sailing time and economy, the ship sailing along the original route is the most efficient and energy-saving way, so the present application takes into account both aspects, if d 0_1 is less than or equal to 3 nautical miles, the heading is immediately adjusted; otherwise, the ship continues to sail along the original route, and when it is 3 nautical miles away from the nearest collision point A0, the heading is adjusted.

[0100] In a specific embodiment of the present application, assuming that the turning starting point is P2, the corresponding longitude and latitude coordinates are (lon self_2 , lat self_2 ), and d 0_1 <=3 nautical miles, then the ship needs to immediately start adjusting the heading at the current position, and the calculation formula of the turning starting point P2 is as follows:

[0101]

[0102] wherein: (lon self_1 , lat self_1 ) are the longitude and latitude coordinates of the current position point of the ship; if d 0_1 >3 nautical miles, the corresponding position point distances between the ship and the nearest collision danger point at the 1st, 2nd, 3rd, …, i time synchronization points are calculated in turn, when the distances between the ship and the nearest collision danger point at the i time synchronization point and the i+1 time synchronization point are respectively before and after 3 nautical miles, the ship position point corresponding to the i time synchronization point is the turning starting point P2. Let the mutual distance between the ship position point corresponding to the i time synchronization point and the nearest collision danger point be d i , and the mutual distance between the ship and the nearest collision danger point at the i+1 time synchronization point be di+1 The calculation formula of the turning starting point P2 is as follows:

[0103] P2 = p i , d i ≥ 3 miles, d i+1 < 3 miles

[0104] Wherein: p i represents the position of the ship corresponding to the ith time synchronization point;

[0105] S4: Calculate the turning angle by trial method: determine the heading angle adjustment range, use the trial method to perform step-by-step trial calculation at the turning starting point described in S3, according to the heading angle adjustment range, increase the heading angle from small to large according to a specific step length, execute S2 step until a roundabout angle that satisfies the smooth navigation of the ship in the future is found, and roundabout according to the roundabout angle;

[0106] S4 includes the following steps:

[0107] S41: Determine the heading angle adjustment range: set the heading angle adjustment range and step length according to the relevant requirements and rules, perform exploratory route exploration starting from 15° with a step length of 5°, and set the maximum adjustment angle to 60° deflection angle; in the specific embodiment of the present application, exploratory route exploration is performed starting from 15° with a step length of 5° according to the rules of maritime collision avoidance and the habit of starting a ship, and the maximum adjustment angle is set to 60° deflection angle; let the heading angle deflection angle be σ cog , which is controlled as follows:

[0108]

[0109] S42: Step-by-step trial calculation: use the trial method to perform step-by-step route exploration starting from the minimum heading angle (15°) of the heading angle adjustment range; execute S21-S24 steps to calculate the collision risk points of the ship along a specific heading angle, and judge whether the smooth navigation condition of the ship in the roundabout phase is met according to the number of collision risk points; the smooth navigation condition is that the ship has no collision risk with other ships on the new route within 1 hour after adjusting the heading at the turning starting point; the roundabout phase is the phase in which the ship sails along a specific heading angle.

[0110] In the specific embodiment of the present application, σ cogWithin the range of values, adjust the course according to the minimum deflection angle of 15° and in 5° increments, and execute steps S21-S24 to recalculate the corresponding distances (mutual distances) between the ship and other ships. Initially, the ship uses its latest position as the reference. After determining the turn, the ship's course changes, and subsequent calculations will use P2 as the reference. During this process, it is assumed that other ships do not change their course, so their positions at the start of the calculation remain unchanged. Therefore, after the ship's course is adjusted, the time synchronization relationship of other ships remains unchanged, but the time synchronization relationship of the ship itself changes. Assume the starting point of the turn, P2, is the i-th... p2 There are several time synchronization points, and the corresponding time of the navigation time synchronization point is t. p2self The formula for calculating the time synchronization relationship between this ship and other ships is as follows:

[0111]

[0112] Wherein: T s ' elf (i) represents the time difference between the i-th time synchronization point after the ship turns and the turning point P2; T o ' ther (i) represents the time difference between the i-th time synchronization point of the other ship and its initial position; t represents the initial time; t other0 This indicates the initial time of the other ship.

[0113] Let the ship's new course after adjustment be cog' self speed sog self The coordinates of the ship's subsequent position will remain unchanged, and P2 will be used as a reference for subsequent position calculations. Assume the latitude and longitude coordinates of P2 are (lon...). self_2 ,lat self_2 Let P2 be the starting point of the turning point and the i-th turning point between the ship and another ship. p2 The formula for calculating the latitude and longitude coordinates of the ship's position at the time synchronization point after the course adjustment, i.e., after the turning start point P2, is as follows:

[0114]

[0115] Among them: (lon' selfi ,lat' selfi () represents the latitude and longitude coordinates of the ship at the i-th time synchronization point after turning; R is the Earth's radius, approximately 6371 kilometers;

[0116] Assuming all other ships maintain their original speed and course, the latitude and longitude coordinates of the i-th time synchronization point of the other ships are (lon otheri lat otheri If the latitude and longitude coordinates of other ships are to be calculated, the formula described in S22 can be used as a reference.

[0117] Based on the ship's latitude and longitude coordinates (lon' selfi ,lat' selfi ) and the latitude and longitude coordinates of other ships (lon otheri lat otheri The distances between the vessel and other vessels during the circumnavigation phase are calculated using the following formula:

[0118] d i '=R×acos(sin(lon' selfi )×sin(lon otheri )+

[0119] cos(lon' selfi )×cos(lon otheri )×cos(lat otheri -lat s ' elfi ))

[0120] Where: d' i This represents the distance between the ship and other ships at the i-th time synchronization point during the circumnavigation phase; R is the Earth's radius, approximately 6371 kilometers.

[0121] S43: Determine the smooth passage angle: If the smooth passage conditions are met, then this specific heading angle is the turning angle that allows the vessel to navigate smoothly during the passage phase; if the smooth passage conditions are not met, continue with step S42 until a turning angle that guarantees smooth passage during the passage phase is found. In a specific embodiment of the invention, the mutual distance d' between the vessel and other vessels at all time synchronization points during the passage phase at a specific angle is calculated. i If the course adjustment begins at a specific heading angle of 15° + j * 5°, where j is an integer between 0 and 9, and the collision risk point between the vessel and other vessels is 0 within the next hour, then this heading angle cog' self The turning angle is determined to be the one that allows for smooth passage during the detour phase; otherwise, if there is still a risk of collision with other vessels, the yaw will continue to be increased in increments of 5° within the prescribed heading angle adjustment range until the collision risk point between the vessel and other vessels is zero within the next hour after the heading adjustment begins; let cog' be the first heading angle to meet the conditions during the trial. self0 Then it should satisfy the following relationship:

[0122]

[0123] Where: n represents the number of time synchronization points within 1 hour after the course adjustment begins; d T Indicates the minimum safe distance between vessels; d' i The distance between the corresponding positions of this vessel and other vessels; cogself is the heading angle in the latest AIS data of the ship;

[0124] S5: Regression point calculation: After the rounding in S4, the appropriate regression point range is determined, and the points in the regression point range are sequentially subjected to the collision avoidance calculation in the regression process, and a bidirectional stepping method is adopted until the point that can avoid all other ships and safely return to the original channel is found, which is the regression point; specifically including the following steps:

[0125] S51: Regression point range determination: The course regression is performed between half an hour to one hour after the rounding stage starts, and the regression point is within the determined regression point range, and the formula is as follows:

[0126]

[0127] Wherein: p m is the first time synchronization point after half an hour of the start of the rounding stage, i.e. the first time synchronization point in the regression point range; p n is the last time synchronization point one hour before the start of the rounding stage, i.e. the last time synchronization point in the regression point range; p x is the assumed regression point, p x takes a value between p m and p n ;

[0128] S52: Regression process collision avoidance calculation: The regression process collision avoidance calculation refers to the calculation process of performing channel regression from p x , following a certain heading angle, to successfully round all dangerous ships and return to the original channel. Let A e be the farthest point in the collision danger point set of the original channel, i.e. the last collision danger point; suppose the ship attempts to return from the assumed regression point p x to the first time synchronization point position 3 nautical miles after the farthest collision danger point A e + 3, and let the longitude and latitude coordinate position of p x be (lon px , lat px ), and the longitude and latitude coordinate position of the first time synchronization point 3 nautical miles after A e + 3 be (lon ae+3 , lat ae+3 ), then the ship's regression heading angle cog s " elf The calculation formula is as follows:

[0129]

[0130] Wherein: (lon px , lat px ) is the assumed regression point p xLatitude and longitude coordinates; (lon) ae+3 ,lat ae+3 (A) represents the furthest collision hazard point. e The latitude and longitude coordinates of the first time synchronization point after +3 nautical miles, i.e., the assumed latitude and longitude coordinates of the regression landing point; with the assumed regression point p x As the new reference point for this ship, cog s " elf To determine the new course angle of the vessel, S21-S24 are executed to calculate and count the collision risk points between the vessel and other vessels, thereby determining whether there is a risk of collision with other vessels during the return process.

[0131] S53: Determining the regression point: Determining the regression point involves determining p based on the calculation results. x The process of determining whether a point is suitable as a regression point. The determination of the regression point uses a two-way step calculation: first, assuming p... x Assuming the original course remains unchanged, and assuming the ship is at the last collision hazard point A in the original course... e The first time synchronization point 3 nautical miles away (denoted as) A regression analysis is performed to calculate the risk of collision between the vessel and other vessels. If no collision risk is detected during the regression, the regression point p can be assumed. x That is, the regression point P3; if p x arrive If the return route poses a collision risk, then collision hazard point A will be selected. e The second time synchronization point, located 3 nautical miles away (denoted as...). Perform regression and calculate p. x arrive Is the return route safe? And so on, assuming the original route... If there are m time synchronization points between the farthest planned point P5 and point P5, then try to synchronize from point P in sequence. x The route is retraced through these m points until a safe return route is found; the farthest planned point is the position corresponding to the ship maintaining its current state for 6 hours from the current time. The calculation formula is as follows:

[0132]

[0133] Where: c1, c2, ..., c m p x The number of collision hazard points on m return routes to m time synchronization points. Calculated in ascending order from 1 to m, the formula for calculating the return point P3 is as follows:

[0134] P3 = p t (1≤t≤m,c t =0)

[0135] If from p xIf a smooth return route cannot be found to the m time synchronization points, then the p x Continue to move forward to p x+1 , repeat the above process, calculate p x+1 The return route of the original route m time synchronization points to determine p x+1 Whether to meet the return condition. In this way, until the final return point P3 that meets the condition is found.

[0136] S6: Return point calculation: determine the return point of the original route according to the return point confirmed in S5;

[0137] Specifically, the return point calculation is the process of calculating the position of the ship returning to the original route, mainly including determining the return point of the ship returning to the original route; When determining the return point in S5, multiple attempts are needed between the assumed return point p x Point and the farthest collision danger point A e Add 3 nautical miles to the farthest point P5 of this route planning, and finally determine p x →p t As a safe return route with a collision danger point of 0. Let P4 be the return point, then the return point calculation formula is:

[0138] P4=p t

[0139] P4=p t

[0140] Where: p t Indicates the return point corresponding to the safe return to the original route;

[0141] S7: New route determination: according to the current position of the ship, the turning start point calculated in S3, the return point calculated in S5, the return point calculated in S6, and the farthest point of the route planning, determine the new route of the ship by connecting the five points;

[0142] Specifically, the new route determination is the process of finally determining a new route according to the above calculation results, mainly including five points to determine the new route; As described above, the current position P1 of the ship, the turning point P2, the return point P3, the return point P4 and the farthest point P5 have been determined, and the route is planned in a straight line manner, therefore, the new route is obtained by directly connecting the five points.

[0143] Second embodiment, an AIS-based group ship collision avoidance route automatic planning system

[0144] The embodiments of the present application provide an AIS-based group ship collision avoidance route automatic planning system, which comprises, connected in sequence, an AIS data acquisition and analysis module for acquiring and analyzing AIS original message data of a ship under navigation to obtain ship AIS data, a route collision danger point calculation and statistics module for calculating and counting collision danger points of the ship and other ships and constructing a collision danger point set according to the ship AIS data acquired by the AIS data acquisition and analysis module, a turning start point calculation module for calculating a turning start point according to the distance between the nearest collision danger point and the corresponding position point of the current position of the ship, a turning angle calculation module for finding a turning angle that can meet the smooth navigation condition by using a trial method within a heading angle adjustment range, a regression point calculation module for calculating a regression point by using a bidirectional stepping method within a regression point range, a regression landing point calculation module for determining the landing point of the ship back to the original route according to the regression point, and a new route determination module for connecting the current position of the ship, the turning start point, the regression point, the regression landing point and the farthest point of the route planning to obtain a new route of the ship.

[0145] The route collision danger point calculation and statistics module calculates a plurality of time points in a future period of time according to the ship AIS data acquired by the AIS data acquisition and analysis module, taking the current time as a reference and a preset time period as a time interval, calculates the corresponding position point distances of the ship and other ships at the plurality of time points, counts the collision danger points of the ship and other ships according to the corresponding position point distances, and constructs a collision danger point set.

[0146] The turning angle calculation module determines a heading angle adjustment range, and the turning start point calculated by the turning start point calculation module is calculated by using a trial method in a step-by-step trial calculation manner. According to the heading angle adjustment range, the heading angle is increased in a specific stepping length from small to large, and the collision danger point statistics are performed by using the route collision danger point calculation and statistics module until a turning angle that can meet the smooth navigation of the ship in a future period of time is found, and the ship is turned according to the turning angle. The smooth navigation refers to that the number of collision danger points is 0.

[0147] The regression point calculation module determines a suitable regression point range after the turning angle calculated by the trial method is determined, and performs the collision avoidance calculation in a regression process for the points in the regression point range in sequence, and calculates until a point that can avoid all other ships and safely return to the original route is found, i.e., the regression point, by using a bidirectional stepping method.

Claims

1. An AIS-based automatic planning method for collision avoidance route of a group of ships, characterized in that, The method comprises the following steps: S1: AIS data acquisition and analysis: obtaining AIS original message data of a ship under navigation, and analyzing the AIS original message data to obtain ship AIS data; S2: Collision risk point calculation and statistics: based on the ship AIS data obtained in S1, taking the current time as a reference and a preset time period as a time interval, a plurality of time points in a future period of time are calculated, and the corresponding position point distances between the own ship and other ships at the plurality of time points are calculated according to the plurality of time points, and the collision risk points between the own ship and other ships are counted according to the corresponding position point distances, and a collision risk point set is constructed; S3: Calculation of turning starting point: selecting the nearest collision risk point from the collision risk point set constructed in S2, and calculating a turning starting point according to the corresponding position point distance between the nearest collision risk point and the current position of the own ship; S4: Calculation of turning angle by trial method: determining a heading angle adjustment range, performing step-by-step trial calculation at the turning starting point in S3 using the trial method, increasing the heading angle from small to large according to a specific step length, and performing S2 until a smooth passing angle is found for the own ship in the future period of time, and the own ship is turned according to the passing angle; S5: Calculation of return point: determining a suitable return point range after turning in S4, and sequentially performing collision avoidance calculation for the points in the return point range, and calculating until a point that can avoid all other ships and safely return to the original channel is found, which is the return point; S6: Calculation of return landing point: determining the landing point of the own ship returning to the original channel according to the return point confirmed in S5; S7: Determination of new route: determining the new route of the own ship by connecting five points according to the current position of the own ship, the turning starting point calculated in S3, the return point calculated in S5, the return landing point calculated in S6, and the farthest point of the route planning.

2. The AIS-based group ship collision avoidance route automatic planning method according to claim 1, characterized in that, The ship under navigation in S1 is a ship equipped with a shipboard automatic identification system, and the specific process of AIS data acquisition and analysis is as follows: an AIS isolating distributor connected with the shipboard automatic identification system is installed on the ship under navigation, and a serial port server, a switch and an analysis server are connected in sequence; the shipboard automatic identification system is responsible for receiving all types of AIS broadcast signals of all ships within an effective range around the own ship, and provides an external interface, synchronously and in parallel outputs a signal to the serial port server through the AIS isolating distributor, converts the AIS broadcast signal in serial port format into a network signal by the serial port server, and then connects the network signal to the switch, and then connects the network signal to the analysis server for decoding and analysis to obtain ship AIS data.

3. The AIS-based group ship collision avoidance route automatic planning method according to claim 2, characterized in that, The AIS original message data is transmitted by compressed ASCII code, complies with the NMEA0183 protocol, and is divided into clear text and cipher text; therefore, the decoding and analysis of the network signal by the analysis server is to analyze the A and B type messages starting with "!AIVDM", and extract ship position information, navigation dynamics and static parameters therefrom; the navigation dynamics and static parameters include MMSI, ship name, heading and speed.

4. The AIS-based group ship collision avoidance route automatic planning method according to claim 2, characterized in that, The preset time period in S2 is 10 seconds, and the future time period is 6 hours; the future time period in S4 is 1 hour.

5. The AIS group ship collision avoidance based route automatic planning method according to claim 4, characterized in that, S2 specifically comprises the following steps: S21: Time synchronization between the ship and the other ship: taking the current time as a reference point and a preset time period as a time interval, a plurality of time points in a future time period are calculated, and a time difference between the plurality of time points and the time in the latest AIS data of the ship and the other ship is calculated, the plurality of time points being time synchronization points; the relationship between the i th time synchronization point and the time in the latest AIS data of the ship and the other ship is calculated according to the following formula: Wherein: T self (i) represents the time difference between the i th time synchronization point and the time in the latest AIS data of the own ship; t self0 represents the time in the latest AIS data of the own ship; T other (i) represents the time difference between the i th time synchronization point and the time in the latest AIS data of the other ship; t other0 represents the time in the latest AIS data of the other ship; t represents the current time; S22: Future time and position synchronization between the ship and the other ship: on the basis of the time synchronization in S21, assuming that all ships remain unchanged in the current state, the heading angle, speed, and latitude and longitude coordinates in the latest ship AIS data collected according to the current time S1 are used to calculate the latitude and longitude coordinates of the ship and the other ship corresponding to the plurality of time synchronization points in S21; The latitude and longitude coordinates of the ship are calculated according to the following formula: wherein: (lon selfi , lat selfi ) represents the longitude and latitude coordinates of the i-th time synchronization point; T self (i) represents the time difference between the i-th time synchronization point and the time in the latest AIS data of the ship; (lon self0 , lat self0 ), sog self , cog self represent the longitude and latitude coordinates of the position, the speed, and the heading angle in the latest AIS data of the ship, respectively; and R represents the radius of the earth. The latitude and longitude coordinates of the other ship are calculated according to the following formula: wherein: (lon otheri , lat otheri ) represents the longitude and latitude of the i-th time synchronization point; T other (i) represents the time difference between the i-th time synchronization point and the time in the latest AIS data of the other ship; (lon other0 , lat other0 ), sog other , cog other represent the longitude and latitude of the position, the speed, and the heading angle in the latest AIS data of the other ship, respectively; and R represents the radius of the earth. S23: Corresponding position point distance calculation: the latitude and longitude coordinates of the ship and the other ship in S22 are used to calculate the mutual distance between the ship and the other ship corresponding to the plurality of time synchronization points, to obtain a plurality of corresponding position point distances between the ship and the other ship; the corresponding position point distance calculation formula is as follows: d i =R×acos(sin(lon selfi )×sin(long otheri )+cos(lon selfi )×cos(long otheri )×cos(lat otheri -lat selfi )) where: (lon selfi , lat selfi ) and (lon otheri , lat otheri ) represent the longitude and latitude coordinates of the i-th time synchronization point of the own ship and the other ship, respectively; R is the radius of the earth; S24: Collision risk point calculation and statistics: the minimum safety distance is determined based on the rules for ship collision avoidance, and if the corresponding position point distance in S23 is less than the minimum safety distance, it is determined that the other ship has a collision risk with the ship, and the time and position when the collision risk occurs are recorded, and the number of collision risks is counted, and the calculation formula is as follows: wherein: n represents the number of all time synchronization points in future time; d T represents the minimum safety distance of the ship; d i represents the distance between the i-th time synchronization point and the corresponding position point of the other ship; N represents the number of time synchronization points whose corresponding position point distance is less than the minimum safety distance of the ship; A represents the set of corresponding position point distances less than the minimum safety distance, i.e. the set of collision danger points, which includes the time, position and corresponding position point distance corresponding to each collision danger point in the set.

6. The AIS-based group ship collision avoidance route automatic planning method according to claim 5, characterized in that, S3 comprises the following steps: S31: Determining the nearest collision risk point: the nearest collision risk point is the first point in the set of collision risk points of the ship, that is, the point with the smallest time; S32: Steering starting point calculation: the time, position, speed, and heading angle in the latest AIS data of the ship are brought into the formulas in S21-S22 to calculate the latitude and longitude coordinates of the current position of the ship; the latitude and longitude coordinates of the current position of the ship and the nearest collision risk point are brought into the formula in S23 to calculate the corresponding position point distance between the ship and the nearest collision risk point; if the corresponding position point distance between the current position of the ship and the nearest collision risk point is less than or equal to 3 nautical miles, the current position of the ship is the steering starting point of the current route planning; otherwise, the ship continues to sail along the original route, and when the distance to the nearest collision risk point is less than or equal to 3 nautical miles, the heading is adjusted, and the point at which the heading adjustment begins is the steering starting point.

7. The AIS-based group ship collision avoidance route automatic planning method according to claim 5, characterized in that, S4 comprises the following steps: S41: Determining the heading angle adjustment range: the heading angle adjustment range and the step length are set according to the relevant requirements and rules, the exploratory route exploration is performed starting from 15° with a step length of 5°, and the maximum adjustment angle is set to 60° deflection angle; S42: Stepwise trial calculation: using the trial method to perform stepwise route exploration from the minimum heading angle of the heading angle adjustment range; performing S21-S24 step calculation and counting the collision risk points of the ship and other ships for the ship sailing along a certain heading angle, and judging whether the smooth navigation condition of the ship in the detour phase is met according to the number of collision risk points; the smooth navigation condition is that the ship has no collision risk with other ships on the new route within 1 hour in the future after adjusting the heading from the turning starting point; the detour phase is the phase in which the ship sails along a certain heading angle; S43: Determine the smooth detour angle: if the smooth navigation condition is met, the certain heading angle is the turning angle that can smoothly navigate in the detour phase; if the smooth navigation condition is not met, continue to perform S42 step until a turning angle that can smoothly navigate in the detour phase is found.

8. The AIS-based group ship collision avoidance route automatic planning method according to claim 7, characterized in that, S5 includes the following steps: S51: Regression point range determination: selecting a route regression between half an hour to 1 hour after the start of the detour phase, and the regression point is in the determined regression point range, and the formula is as follows: where: p m is the first time synchronization point in the range of the regression point; p n is the last time synchronization point in the range of the regression point; p x is the assumed regression point, the assumed regression point p x takes values sequentially between p m and p n . S52: Collision avoidance calculation in the return process: set A e is the farthest point in the original channel collision danger point set, i.e. the last collision danger point; assuming that the ship attempts to return from the assumed return point p x to the farthest collision danger point A e after the first time synchronization point position 3 nautical miles away, the ship returns to the heading angle cog self The calculation formula is as follows: wherein: (lon px ,lat px ) is the assumed reentry point p x longitude and latitude coordinates; (lon ae+3 ,lat ae+3 ) is the first time synchronization point A e +3 nautical miles away, i.e. the assumed reentry point p x longitude and latitude coordinates; taking the assumed reentry point p self as the new reference point of the own ship, cog self as the new heading angle of the own ship, performing S21-S24 calculation and counting the collision risk points between the own ship and other ships, so as to determine whether the own ship has collision risk with other ships during the reentry process. S53: Determine the regression point: the confirmation of the regression point adopts a bidirectional stepping method, which is as follows: assuming that the regression process of S52 is collision-free, p x is determined as the regression point; if the regression process has a collision risk, A e is selected again, and the process of S21-S24 is repeated to determine whether the ship has a collision risk with other ships during the regression process; by analogy, assuming that A e is selected on the original route, there are m time synchronization points between the third nautical mile outside and the farthest point of the route planning, and the positions corresponding to the m time synchronization points are tried in turn from p x to the regression line of p x to the original route m time synchronization points to determine whether p x+1 satisfies the regression condition; by analogy, until the regression point that satisfies the condition is finally found. x+1 x+1 ​​ 9. The AIS-based group ship collision avoidance route automatic planning method according to claim 8, characterized in that, The regression drop point in S6 is the point of intersection of the collision-free route found in S52-S53 steps and the original route, which is the regression drop point.

10. An AIS-based automatic planning system for collision avoidance route of a group of ships, characterized in that, The method comprises the following steps of: sequentially connecting an AIS data acquisition and analysis module for acquiring and analyzing AIS original message data of a ship under navigation to obtain ship AIS data, a route collision risk point calculation and statistics module for calculating and counting collision risk points of the ship and other ships and constructing a collision risk point set according to the ship AIS data acquired by the AIS data acquisition and analysis module, a turning starting point calculation module for calculating a turning starting point according to a distance between a nearest collision risk point and a corresponding position point of the current position of the ship, a turning angle calculation module for finding a turning angle that can meet the smooth navigation condition in a heading angle adjustment range by using a trial method, a regression point calculation module for calculating a regression point in a regression point range by using a bidirectional step method, a regression drop point calculation module for determining a drop point of the ship returning to the original route according to the regression point, and a new route determination module for connecting the current position of the ship, the turning starting point, the regression point, the regression drop point and a farthest point of the route planning to obtain a new route of the ship. The route collision risk point calculation and statistics module calculates a plurality of time points in a future period of time according to the ship AIS data acquired by the AIS data acquisition and analysis module, takes the current time as a reference and takes a preset time period as a time interval, calculates corresponding position point distances between the ship and other ships at the plurality of time points, counts collision risk points of the ship and other ships according to the corresponding position point distances, and constructs a collision risk point set. The turning angle calculation module determines a heading angle adjustment range, uses a trial method to perform step-by-step trial calculation at the turning starting point calculated by the turning starting point calculation module, increases the heading angle from small to large according to a specific step length according to the heading angle adjustment range, and performs collision danger point statistics by using the route collision danger point calculation and statistics module until a turning angle is found that allows the ship to smoothly pass in a future period of time, and the ship turns according to the turning angle; the smooth passing refers to that the number of collision danger points is 0; The regression point calculation module determines a suitable regression point range after the trial method turning angle calculation module determines the turning, and performs collision avoidance calculation on points in the regression point range in sequence, and calculates until a point is found that can avoid all other ships and safely return to the original route, which is the regression point.

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