Group ship collision avoidance route automatic planning method and system based on AIS

Abstract

The invention relates to the technical field of navigation automation and informatization, in particular to a method, a system and a device for automatically planning a group ship collision avoidance route based on an AIS (Automatic Identification System). The method comprises the steps of data acquisition and analysis; calculating and counting air route collision dangerous points; calculating a steering starting point; calculating a heading angle by a heuristic method; calculating regression points; calculating a regression drop point and determining a new route. The system comprises an AIS data acquisition and analysis module, an air route collision dangerous point calculation and statistics module, a steering starting point calculation module, a steering angle calculation module, a regression point calculation module, a regression drop point calculation module and a new air route determination module. By adopting the method and the system, the problems of insufficient timeliness and poor accuracy of automatic generation of the air route in the existing air route planning technology can be solved, and the shipping industry is promoted to develop towards a more efficient, safer and environment-friendly direction.

Description

Technical Field

[0001] The invention belongs to the technical field of navigation automation and information technology, and in particular relates to a method and system for automatically planning a group ship collision avoidance route based on AIS. Background Art

[0002] In the booming global trade and economy, the shipping industry, as the artery connecting the world economy, continues to demonstrate its indispensable importance. With the continuous injection of capital and the rapid innovation of technology, shipping companies are accelerating the modernization of their fleets, significantly improving the carrying capacity and operational efficiency of ships by building high-efficiency new ships and upgrading existing fleets. What is particularly critical is that the deep integration of automation and intelligent technology has brought unprecedented safety performance improvements and leaps in transportation efficiency to the shipping industry, further consolidating its core position in the global trade system.

[0003] However, the current field of ship route planning still faces many challenges. Although the traditional planning method based on preset waypoints has met basic navigation needs to a certain extent, its flexibility and adaptability are particularly insufficient when facing complex and changing marine environments, dynamically adjusted traffic conditions, and sudden maritime incidents. In addition, the subjectivity of manual operations and the limitations of simple calculation methods make it difficult to ensure high accuracy and efficiency in route planning, especially at a time when traffic volume has surged and route congestion has become the norm, which has exacerbated navigation risks and cost burdens.

[0004] In this context, the importance of ship route planning as a core link in the shipping industry is self-evident. It is not only the cornerstone for ensuring ship navigation safety, optimizing transportation costs, and promoting environmental friendliness, but also an important indicator for measuring the competitiveness and intelligence level of shipping companies. Formulating a route that not only meets navigation safety regulations but also maximizes transportation efficiency and economic benefits is the primary prerequisite for ships to successfully complete their voyage missions. Especially in today's rapidly changing science and technology, the realization of automatic planning and intelligent adjustment of ship routes is of milestone significance for promoting the development of unmanned navigation technology for ships.

[0005] However, the current field of ship route planning still faces many challenges. Although the traditional planning method based on preset waypoints meets the basic navigation needs to a certain extent, its flexibility and adaptability are particularly insufficient when facing the complex and changeable marine environment, dynamically adjusted traffic conditions and sudden maritime events. In addition, the subjectivity of manual operation and the limitations of simple calculation methods make it difficult to ensure the high accuracy and efficiency of route planning, especially at a time when traffic volume has surged and route congestion has become the norm, which has aggravated the navigation risks and cost burden. Although in recent years, academia and industry have proposed a variety of automatic route generation methods based on electronic charts, ant colony algorithms, and water depth shortest time strategies, these studies are mostly in the stage of theoretical discussion and laboratory verification, and their reliability, real-time performance and wide applicability in practical applications have yet to be fully verified and optimized. Especially for long-distance, cross-sea complex routes, existing methods are difficult to meet the urgent needs of instant generation and precise navigation, which limits the improvement of the overall intelligence level of the shipping industry. Summary of the invention

[0006] The present invention solves the problem that the existing route planning method has insufficient timeliness and accuracy in automatically generating routes 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 invention is as follows:

[0008] A method for automatically planning a collision avoidance route for a group of ships based on AIS comprises the following steps:

[0009] S1: AIS data collection and analysis: obtaining the AIS original message data of the ship at sea, and analyzing the AIS original message data to obtain the ship AIS data;

[0010] S2: Calculation and statistics of route collision danger points: Based on the ship AIS data obtained in S1, multiple time points in the future are calculated with the current time as the reference and the preset time period as the time interval, and the corresponding position point distances between the own ship and other ships corresponding to the multiple time points are calculated according to the multiple time points, and the collision danger points of the own ship and other ships are counted according to the corresponding position point distances, and a collision danger point set is constructed;

[0011] S3: Calculation of the starting point of turning: Select the nearest collision danger point from the set of collision danger points constructed in S2, and calculate the starting point of turning according to the distance between the nearest collision danger point and the corresponding position point of the current position of the ship;

[0012] S4: Calculation of steering angle by heuristic method: Determine the adjustment range of the heading angle, perform step-by-step heuristic calculation using the heuristic method at the turning starting point described in S3, increase the heading angle from small to large according to a specific step length according to the adjustment range of the heading angle, and execute step S2 until a detour angle that satisfies the smooth passage of the ship in the future is found, and the ship detoured according to the detour angle;

[0013] S5: Calculation of regression point: After detouring in S4, determine the appropriate regression point range, perform regression process collision avoidance calculation on the points within the regression point range in turn, and use the two-way step method to calculate until a point that can avoid all other ships and return to the original course safely is found, which is the regression point;

[0014] S6: Return point calculation: Determine the return point of the ship based on the return point confirmed in S5;

[0015] S7: Determine the new route: Determine the new route of the ship by connecting the five points based on the current position of the ship, the turning starting point calculated by S3, the return point calculated by S5, the return landing point calculated by S6 and the farthest point of the route planning.

[0016] Preferably, the ship at sea in S1 is a ship equipped with a shipborne automatic identification system, and the specific process of AIS data collection and analysis is: an AIS isolation distributor connected to the shipborne automatic identification system is installed on the ship at sea, and is connected to the serial port server, the switch and the analysis server in sequence; the shipborne automatic identification system is responsible for receiving various AIS broadcast signals of all ships within the effective range around the ship, and providing an external interface, and synchronously and parallelly outputting one signal to the serial port server through the AIS isolation distributor, and the serial port server converts the AIS broadcast signal in the serial port format into a network signal and then connects it to the switch, and then connects the network signal to the analysis server for decoding and parsing to obtain the ship AIS data.

[0017] Preferably, the AIS original message data is transmitted using compressed ASCII code, complies with the NMEA0183 protocol, and is divided into plain text and coded text; therefore, the decoding and parsing of the network signal by the analysis server is to parse the A and B class messages starting with "!AIVDM", and extract the ship's 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; and the future period of time in S4 is 1 hour.

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

[0020] S21: Time synchronization between the ship and other ships: taking the current time as the reference point and the preset time period as the time interval, multiple time points within a period of time in the future are calculated, and the time difference between the multiple time points and the time in the latest AIS data of the ship and other ships is calculated. The multiple 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 other ships is calculated as follows:

[0021]

[0022] Where: T self (i) represents the time difference between the ith time synchronization point and the time in the latest AIS data of the own ship; t self0 Indicates the time of the latest AIS data of this ship; T other (i) represents the time difference between the ith time synchronization point and the time in the latest AIS data of other ships; t other0 Indicates the time in the latest AIS data of other ships; t indicates the current time;

[0023] S22: Synchronize the future time positions of own ship and other ships: Based on the time synchronization in S21, assuming that all ships keep their current status unchanged, the heading angle, speed, longitude and latitude coordinates of own ship and other ships corresponding to multiple time synchronization points in S21 are calculated according to the heading angle, speed, longitude and latitude coordinates of the latest ship AIS data collected in step S1 at the current time;

[0024] The calculation formula of the latitude and longitude coordinates of the ship is as follows:

[0025]

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

[0027] The calculation formula of the latitude and longitude coordinates of the other ship is as follows:

[0028]

[0029] Where: (lon otheri ,lat otheri ) represents the longitude and latitude coordinates of the other ship at the ith time synchronization point; T other(i) represents the time difference between the ith time synchronization point and the time in the latest AIS data of other ships; (lon other0 ,lat other0 )、sog other 、cog other They represent the latitude and longitude coordinates, speed, and heading angle of the other ship’s latest AIS data; R represents the radius of the earth;

[0030] S23: Calculate the distance between corresponding position points: Use the longitude and latitude coordinates of the own ship and the other ship in S22 to calculate the mutual distance between the own ship and the other ship corresponding to multiple time synchronization points, and obtain multiple corresponding position point distances between the own ship and the other ship; the corresponding position point distance calculation formula is as follows:

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

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

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

[0034] S24: Calculation and statistics of collision risk points: Determine the minimum safe distance based on the rules for avoiding collisions between ships at sea. If the distance between the corresponding position points in S23 is less than the minimum safe distance, it is determined that there is a risk of collision between the other ship and the own ship, and the time and position when there is a risk of collision are recorded, and the number of risk of collision is counted. The calculation formula is as follows:

[0035]

[0036] Where: n represents the number of all time synchronization points in the future time; d T Indicates the minimum safe distance of the ship; d i represents the distance between the corresponding position points of the ship and other ships at the i-th time synchronization point; 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 danger point set, which includes the time, position and corresponding position point distance corresponding to each collision danger point.

[0037] Preferably, S3 includes the following steps:

[0038] S31: Determine 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, that is, the point with the shortest time;

[0039] S32: Calculation of the starting point of turning: Substitute the time, position, speed and heading angle in the latest AIS data of the ship into the formula described in S21-S22 to calculate the longitude and latitude coordinates of the current position of the ship; Substitute the longitude and latitude coordinates of the current position of the ship and the nearest collision danger point into the formula described in S23 to calculate the distance between the corresponding position points of the ship and the nearest collision danger point; if the distance between the corresponding position points of the current position of the ship and the nearest collision danger point is less than or equal to 3 nautical miles, the current position of the ship is the starting point of the turning for this route planning; otherwise, the ship continues to sail along the original route, and adjusts the course when the distance to the nearest collision danger point is less than or equal to 3 nautical miles, and the point where the course adjustment begins is the starting point of the turning.

[0040] Preferably, S4 comprises the following steps:

[0041] S41: Determine the heading angle adjustment range: set the heading angle adjustment range and step length according to relevant requirements and rules, start from 15° and perform a tentative route exploration with a step length of 5°, and set the maximum adjustment angle to a 60° deflection angle;

[0042] S42: Step-by-step trial calculation: Use the trial method to start step-by-step route exploration from the minimum heading angle in the heading angle adjustment range; perform steps S21-S24 for the own ship sailing along a specific heading angle to calculate and count the collision risk points between the own ship and other ships, and judge whether the smooth navigation conditions of the own ship in the detour phase are met according to the number of collision risk 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 ship starts to adjust the heading at the turning starting point; the detour phase is the phase in which the own ship sails along a specific heading angle;

[0043] S43: Determine the smooth detour angle: If the smooth passage condition is met, the specific heading angle is the turning angle that enables the ship to navigate smoothly during the detour stage; if the smooth passage condition is not met, continue with step S42 until a turning angle that enables smooth navigation during the detour stage is found.

[0044] Preferably, S5 comprises the following steps:

[0045] S51: Determine the range of regression points: Select to perform route regression between half an hour and one hour after the start of the detour phase. The regression point is taken within the determined range of regression points. The formula is as follows:

[0046]

[0047] Where: p mis the first time synchronization point within the range of regression points; p n is the last time synchronization point within the regression point range; p x is the assumed regression point, assuming the regression point p x In order in p m to p n Take values ​​between

[0048] S52: Collision avoidance calculation in regression process: Assume A e is the farthest point in the original collision danger point set, that is, the last collision danger point; assuming that the ship attempts to return from the assumed regression point p described in S51 x To the farthest collision danger point A e +3 nautical miles after the first time synchronization point position returns, then the ship returns to the heading angle cog s " elf The calculation formula is as follows:

[0049]

[0050] Where: (lon px ,lat px ) is the assumed regression point p x Latitude and longitude coordinates; (lon ae+3 ,lat ae+3 ) is the farthest collision danger point A e +3 nautical miles after the first time synchronization point latitude and longitude coordinates, that is, the assumed regression point latitude and longitude coordinates; the assumed regression point p x is the new reference point of own ship, cog s " elf is the new heading angle of the own ship, and S21-S24 are executed to calculate and count the collision risk points between the own ship and other ships, so as to determine whether there is a collision risk with other ships during the return process of the own ship;

[0051] S53: Determine the regression point: The regression point is confirmed by a two-way stepping method, as follows: Assuming that there is no collision risk during the S52 regression process, p can be determined. x is the regression point; if there is a collision risk in the regression process, then select A e The ship returns to the second time synchronization point 3 nautical miles away and repeats S21-S24 to determine whether there is a risk of collision with other ships during the return process. Similarly, assuming that A e If there are m time synchronization points between the last 3 nautical miles and the farthest point of the route planning, try to start from p in turn. x Perform route regression to the position points corresponding to the m time synchronization points until a route without collision risk is found; if not found, then take a detour route p x Continue moving forward to p x+1, repeat the above process to calculate p x+1 The regression line to m time-synchronized points on the original course is used to determine p x+1 Whether the regression conditions are met; and so on, until a regression point that meets the conditions is finally found.

[0052] Preferably, the regression landing point in S6 is the point where the route without collision risk found in steps S52-S53 intersects with the original route, that is, the regression landing point.

[0053] The present invention also provides an automatic planning system for group ship collision avoidance routes based on AIS, comprising an AIS data acquisition and analysis module connected in sequence for acquiring AIS original message data of a ship on the water and analyzing it 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 according to the ship AIS data acquired by the AIS data acquisition and analysis module and constructing a collision danger point set, a turning starting point calculation module for calculating a turning starting 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 the heading angle adjustment range, a regression point calculation module for calculating the regression point by using a two-way stepping method within the regression point range, 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 five points of 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 to obtain the new route of the ship;

[0054] The route collision danger point calculation and statistics module calculates multiple time points in the future based on the ship AIS data obtained by the AIS data collection and analysis module, taking the current time as the reference and the preset time period as the time interval, and calculates the corresponding position point distances between the own ship and other ships corresponding to the multiple time points according to the multiple time points, and counts the collision danger points of the own ship and other ships according to the corresponding position point distances, and constructs a collision danger point set;

[0055] The steering angle calculation module determines the heading angle adjustment range, uses the trial method to perform step-by-step trial calculation at the steering starting point calculated by the steering starting point calculation module, and increases the heading angle from small to large according to a specific step length according to the heading angle adjustment range, and uses the route collision danger point calculation and statistics module to perform collision danger point statistics until a detour angle that satisfies the smooth passage of the ship in the future is found, and the detour is performed according to the detour angle; the smooth passage means that the number of collision danger points is 0;

[0056] After the trial method steering angle calculation module determines the detour, the regression point calculation module determines the appropriate regression point range, performs regression process collision avoidance calculation on the points within the regression point range in turn, and uses the two-way step method to calculate until a point that can avoid all other ships and return to the original course safely is found, which is the regression point.

[0057] Beneficial effects:

[0058] The present invention provides a method and system for automatically planning a group ship collision avoidance route based on AIS. The method comprises: obtaining the original AIS message data of the ship underway and parsing it to obtain the ship AIS data. By obtaining the original AIS message data of the ship underway and parsing it, the key information of the ship underway can be obtained in real time, and the dynamic changes of the ship can be accurately captured; according to the latest AIS data obtained at the current time, the collision danger points between the ship and other ships in the future when the ship is traveling on the current channel are calculated, and statistics are made. The route is adjusted in real time according to the statistical collision danger points, which effectively avoids the navigation caused by information lag. The problem of inaccurate route planning has been solved, which significantly improves the timeliness and accuracy of route planning; the latitude and longitude coordinates of the nearest collision danger point are obtained, the latitude and longitude coordinates of the ship's position are calculated, and the corresponding position point distance between the two is calculated (that is, the mutual distance between the ship's position point and the collision danger point), and the turning starting point is determined according to the mutual distance; after the turning starting point is confirmed, the heading angle adjustment range is determined, and the steering angle is determined by the trial method within the heading angle adjustment range, and the appropriate steering angle is determined to enable the ship to navigate smoothly during the detour stage; after the detour, the appropriate regression point range is determined, and the points within the regression point range are used for regression process collision avoidance calculation, and the two-way step method is used for calculation Until a point is found that can avoid all other ships and return to the original course safely, that is, a safe return route with zero collision risk points is found, thereby determining the return point; the two advanced algorithms of the trial and error method and the two-way step method can flexibly adjust the heading angle and the return point to ensure that the ship meets the conditions for smooth navigation in both the detour stage and the return stage. This dynamic adjustment mechanism makes route planning more flexible and changeable, and can better adapt to various emergencies in actual navigation, reducing navigation risks; the landing point of the ship returning to the original course is determined according to the confirmed return point; the optimized route can reduce unnecessary detours and waiting time, reduce fuel consumption and transportation The new route is finally obtained by connecting the current position of the ship, the turning starting point, the return point, the return landing point and the farthest point of the route planning. The above-mentioned technology integrates AIS data and advanced algorithms to solve the problems of insufficient timeliness and accuracy of automatic route generation for long-distance, cross-sea complex routes in existing route planning methods, realizes the automation and intelligence of route planning, and lays a solid foundation for the development of unmanned navigation technology for ships. This will not only help to enhance the overall competitiveness of the shipping industry, but also promote the entire industry to develop in a more efficient, safe and environmentally friendly direction.

[0059] Based on the synchronization relationship between the latitude and longitude, speed, heading and time in the AIS data of the latest ship at sea and all ships within the effective range around it obtained by the current ship, the future ship position is synchronized at intervals of 10 seconds, the mutual distance between the ship and all surrounding ships (other ships) is calculated in real time, and whether there is a risk of collision between the ship and other ships is determined based on the distance, with high real-time performance.

[0060] The two-way stepping method is used between the farthest collision risk point of the original channel and the farthest point of this route planning to find a safe return route with a collision risk point of 0, and then the return landing point of this route planning is determined. By accurately calculating the collision risk point and planning a route without collision risk, and strictly setting a reasonable safety distance in accordance with the requirements of early and wide giving way, the incidence of collision accidents among multiple ships and groups of ships can be effectively reduced, and the navigation safety can be significantly improved.

[0061] The present invention is designed with the rules for avoiding collisions at sea and the sailing habits of the crew as the theoretical basis, strictly following the requirements of early and wide giving way to ensure a minimum safety distance of 3 nautical miles; at the same time, the present invention adopts a 6-hour long route planning algorithm, which can avoid collisions of multiple ships and groups of ships. The ship route planning should be based on the destination port and combined with the original route design of the ship to achieve safety and efficiency. The principle of the route planning method of the present invention is safe detour and timely return. On the premise of safe detour of the ship, the ship's deviation, return and improved energy efficiency are also considered, which has higher practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 The present invention is a flowchart of a method for automatically planning a group ship collision avoidance route based on AIS according to an embodiment of the present invention.

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

[0064] Figure 3 The present invention is a schematic diagram of an automatic planning system for a group of ships to avoid collision based on AIS according to an embodiment of the present invention. Specific implementation methods

[0066] In order to make the purpose, technical solution and advantages of the present invention more clear, the technical solution is further clearly and completely described below in conjunction with the accompanying drawings of the present invention.

[0067] First group of embodiments: Automatic planning method for ship group collision avoidance route based on AIS

[0068] This group of embodiments provides a method for automatically planning a group ship collision avoidance route based on AIS, such as Figure 1 As shown, the following steps are included:

[0069] S1: AIS data collection and analysis: Obtain the AIS original message data of the ship at sea, and analyze the AIS original message data to obtain the ship AIS data (AIS data of the ship at sea and all ships within the effective range around it); the ship AIS data includes speed, heading angle, time, and position; the position includes longitude coordinates and latitude coordinates; all ships within the effective range around the ship at sea are other ships; the ship at sea is the own ship;

[0070] The ship is a ship equipped with a ship-borne automatic identification system (ship-borne AIS signaler). The AIS data collection and analysis is performed by installing auxiliary equipment ( Figure 2 ) is implemented, specifically as follows: an AIS isolation distributor connected to the shipborne automatic identification system is installed on the ship, and is connected to the serial port server, the switch and the analysis server in sequence; the shipborne automatic identification system is responsible for receiving various AIS broadcast signals of all ships within the effective range around the ship, and providing an external interface, through the AIS isolation distributor, synchronously and parallelly outputting one signal to the serial port server, the serial port server converts the AIS broadcast signal in the serial port format into a network signal and then connects it to the switch, and then connects the network signal to the analysis server for decoding and parsing to obtain AIS data.

[0071] The AIS original message data is obtained from the ship's onboard AIS signaler, transmitted using compressed ASCII code, and complies with the NMEA0183 protocol, which is divided into plaintext and coded messages; therefore, the analysis server decodes and parses the network signal by parsing the A and B class messages starting with "!AIVDM", and extracts the ship's position information, navigation dynamics and static parameters from them; the navigation dynamics and static parameters include MMSI (Maritime Mobile Service Identify, ship identity code), ship name, heading and speed. The functional relationship of the parsing process is described as follows:

[0072]

[0073] Among them: AIS original message data is used as input parameter, and its format is as follows:

[0074] "!AIVDO,1,1,,,16:5eEP0@mWp=of;NR;8qoCR3P00,0*5B"

[0075] NMEA183 (AIS) means that the AIS original 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), latitude (lat);

[0076] S2: Calculation and statistics of route collision danger points: Based on the ship AIS data obtained in S1, with the current time as the reference and the preset time period as the time interval, multiple time points in the future are calculated, and the corresponding position point distances between the ship and other ships corresponding to the multiple time points are calculated according to the multiple time points, and the collision danger points of the ship and other ships are counted according to the corresponding position point distances, and a collision danger point set is constructed; in a specific embodiment of the present invention, the preset time period is 10 seconds, and the future period is 6 hours;

[0077] S2 specifically includes the following steps:

[0078] S21: Time synchronization between the ship and other ships: taking the current time as the reference point and the preset time period as the time interval, multiple time points within a period of time in the future are calculated, and the time difference between the multiple time points and the time in the latest AIS data of the ship and the other ship is calculated. The multiple time points are called time synchronization points; in a specific embodiment of the present invention, taking the current time as the reference point and the time interval of 10 seconds, multiple time points within the next 6 hours are calculated, and the time difference between the multiple time points within the next 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 corresponding time in the latest AIS data is calculated as follows:

[0079]

[0080] Where: T self (i) represents the time difference between the ith time synchronization point and the time in the latest AIS data of the ship; t represents the current time; t self0 Indicates the time of the latest AIS data of this ship; T other (i) represents the time difference between the ith time synchronization point and the time in the latest AIS data of other ships; t other0 Indicates the time in the latest AIS data of other ships; t indicates the current time;

[0081] S22: Synchronize the future time position of the own ship and other ships: Based on the time synchronization in S21, assuming that all ships keep their current status unchanged, the longitude and latitude coordinates of the own ship and other ships corresponding to multiple time synchronization points in S21 are calculated according to the heading angle, speed, and longitude and latitude coordinates in the latest ship AIS data collected in step S1 at the current time; in a specific embodiment of the present invention, the calculation formula for the longitude and latitude coordinates of the own ship at the i-th time synchronization point is derived based on geographical knowledge as follows:

[0082]

[0083] Where: (lon selfi ,lat selfi) represents the longitude and latitude coordinates of the ship at the ith time synchronization point; T self (i) represents the time difference between the ith time synchronization point and the time in the latest AIS data of the ship; (lon self0 ,lat self0 )、sog self 、cog self They represent the latitude and longitude coordinates, speed, and heading angle of the latest AIS data of the ship; R represents the radius of the earth, which is approximately 6371 kilometers;

[0084] Based on geographical knowledge, the calculation formula for the longitude and latitude coordinates of other ships at the i-th time synchronization point is as follows:

[0085]

[0086] Where: (lon otheri ,lat otheri ) represents the longitude and latitude coordinates of the other ship at the ith time synchronization point; T other (i) represents the time difference between the ith time synchronization point and the time in the latest AIS data of other ships; (lon other0 ,lat other0 )、sog other 、cog other They represent the latitude and longitude coordinates, speed, and heading angle of the other ship's latest AIS data; R represents the radius of the earth, which is approximately 6371 kilometers;

[0087] S23: Calculation of distances between corresponding position points: using the latitude and longitude coordinates of the own ship and the other ship described in S22 to calculate the mutual distances between the own ship and the other ship corresponding to multiple time synchronization points, to obtain multiple distances between corresponding position points of the own ship and the other ship; in a specific embodiment of the present invention, based on spherical trigonometry, the formula for the distance between corresponding position points of the own ship and the other ship is as follows:

[0088] d i =R×acos(sin(lon selfi )×sin(lon otheri )+

[0089] cos(lon selfi )×cos(lon otheri )×cos(lat otheri -lat selfi ))

[0090] Where: d i represents the distance between the corresponding position points of the ship and other ships at the ith time synchronization point (mutual distance); R represents the radius of the earth, which is about 6371 kilometers; (lon selfi ,lat selfi )、(lonotheri ,lat otheri ) represent the longitude and latitude coordinates of the i-th time synchronization point of own ship and other ship respectively;

[0091] S24: Calculation and statistics of collision risk points: Determine the minimum safe distance based on the rules for avoiding collisions between ships at sea. If the distance between the corresponding position points in S23 is less than the minimum safe distance, it is determined that there is a risk of collision between the other ship and the own ship, and the time and position when there is a risk of collision are recorded, and the number of risk of collision is counted. The calculation formula is as follows:

[0092]

[0093] Where: n represents the number of all time synchronization points in the future time (6 hours); d T Indicates the minimum safe distance of the ship; d i represents the distance between the corresponding position points of the ship and other ships at the i-th time synchronization point; 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 danger point set, which includes the time, position and corresponding position point distance corresponding to each collision danger point.

[0094] S3: Calculation of the starting point of turning: Select the nearest collision danger point from the set of collision danger points constructed in S2, and calculate the starting point of turning according to the distance between the nearest collision danger point and the corresponding position point of the current position of the ship; specifically, the following steps are included:

[0095] S31: Determine the nearest collision danger point: The nearest collision danger point is the first point in the collision danger point set of the own ship, that is, the point with the shortest time. In a specific embodiment of the present invention, assuming that the point with the shortest time in the collision danger point set A described in S24 is A0, then A0 is the nearest collision danger point. Calculating the turning starting point is the process of determining the most appropriate time between the current position and A0 for the own ship to adjust its course after determining the nearest collision point A0.

[0096] S32: Calculation of the starting point of turning: Substitute the time, position, speed and heading angle in the latest AIS data of the ship into the formula described in S21-S22 to calculate the longitude and latitude coordinates of the current position of the ship; Substitute the longitude and latitude coordinates of the current position of the ship and the nearest collision danger point into the formula described in S23 to calculate the corresponding position point distance (mutual distance) between the ship and the nearest collision danger point; If the mutual distance between the current position of the ship and the nearest collision danger point is less than or equal to 3 nautical miles, the current position of the ship is the starting point of the turning for this route planning; Otherwise, the 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, adjust the course, and the point where the course adjustment begins is the starting point of the turning. In a specific embodiment of the present invention, the calculation formula for the longitude and latitude coordinates of the current position of the ship is as follows:

[0097]

[0098] Where: (lon self_1 ,lat self_1 ) represents the latitude and longitude coordinates of the ship at the current time; (lon self0 ,lat self0 )、sog self 、cog self They represent the latitude and longitude coordinates, speed, and heading angle of the latest AIS data of the ship; R represents the radius of the earth, which is about 6371 kilometers; t represents the current time;

[0099] Furthermore, the latitude and longitude coordinates of the current position of the ship and the latitude and longitude coordinates of the nearest collision danger point are substituted into the formula in S23 to calculate the corresponding position distance d between the current position point of the ship (the current driving position of the ship) and the nearest collision danger point. 0_1 ;

[0100] The rules for avoiding collisions at sea require that ships give way early and give way widely when encountering each other. However, considering the sailing time and economy, it is the most efficient and energy-saving way for ships to sail along the original route. Therefore, the present invention takes both aspects into consideration. 0_1 If the distance is less than or equal to 3 nautical miles, adjust the course immediately; otherwise, continue to sail along the original route and start adjusting the course when the distance to the nearest collision point A0 is 3 nautical miles.

[0101] In a specific embodiment of the present invention, assuming that the turning starting point is P2, the corresponding longitude and latitude coordinates are (lon self_2 ,lat self_2 ),d 0_1 <=3 nautical miles, then the ship needs to start adjusting its course immediately at the current position. The calculation formula for the turning starting point P2 is as follows:

[0102]

[0103] Where: (lon self_1 ,lat self_1 ) is the latitude and longitude coordinates of the current position of the ship; if d 0_1 >3 nautical miles, calculate the corresponding position distances between the ship and the nearest collision danger point at the 1st, 2nd, 3rd, ..., i-th time synchronization points in turn. When the distances between the ship and the nearest collision danger point at the i-th time synchronization point and the i+1-th time synchronization point are respectively around 3 nautical miles, the position point of the ship corresponding to the i-th time synchronization point is the turning starting point P2. Let the mutual distance between the ship's position point corresponding to the i-th time synchronization point and the nearest collision danger point be d i , the mutual distance between the ship and the nearest collision danger point at the i+1th time synchronization point is di+1 At this time, the calculation formula for the turning starting point P2 is as follows:

[0104] P2=p i ,(d i ≥3 nautical miles,d i+1 <3 nautical miles)

[0105] Where: p i Indicates the position of the ship corresponding to the i-th time synchronization point;

[0106] S4: Calculation of steering angle by heuristic method: Determine the adjustment range of the heading angle, perform step-by-step heuristic calculation using the heuristic method at the turning starting point described in S3, increase the heading angle from small to large according to a specific step length according to the adjustment range of the heading angle, and execute step S2 until a detour angle that satisfies the smooth passage of the ship in the future is found, and the ship detoured according to the detour angle;

[0107] S4 includes the following steps:

[0108] S41: Determine the heading angle adjustment range: Set the heading angle adjustment range and step length according to relevant requirements and rules, start from 15°, and perform a tentative route exploration with a step length of 5°, and set the maximum adjustment angle to a 60° deflection angle; in a specific embodiment of the present invention, according to the maritime collision avoidance rules and sailing habits, start from 15°, and perform a tentative route exploration with a step length of 5°, and set the maximum adjustment angle to a 60° deflection angle; let the heading angle deflection angle be σ cog , and its adjustment range is controlled as follows:

[0109]

[0110] S42: Step-by-step trial calculation: Use the trial method to start step-by-step route exploration from the minimum heading angle (15°) of the heading angle adjustment range; execute steps S21-S24 to calculate the collision risk points between the ship and other ships sailing along a specific heading angle, and judge whether the conditions for smooth navigation of the ship in the detour phase are met based on the number of collision risk points; the smooth navigation condition is that there is no risk of collision with other ships on the new route within the next 1 hour after the ship starts to adjust the heading from the turning starting point; the detour phase is the phase in which the ship sails along a specific heading angle.

[0111] In a specific embodiment of the present invention, cogWithin the value range, adjust the heading according to the minimum deflection angle of 15° and the step size of 5°, execute steps S21-S24, and recalculate the corresponding position point distance (mutual distance) between the own ship and the other ship; at the beginning of the calculation, the own ship takes its own latest position as the reference. After determining the turn, the heading of the own ship changes, then the next calculation of the own ship will be based on P2. In this process, it is assumed that the other ship has not changed its heading, so the other ship always takes the position of the other ship at the start of the calculation as the reference, and the reference point remains unchanged. Therefore, after the heading of the own ship is adjusted, the time synchronization relationship with the other ship remains unchanged, but the time synchronization relationship of the own ship has changed. Assuming that the turning starting point P2 is the i-th p2 time synchronization point, the time corresponding to the navigation time synchronization point is t p2self , then the time synchronization relationship between the own ship and other ships is calculated as follows:

[0112]

[0113] Where: T s ' elf (i) represents the time difference between the ith time synchronization point and the turning point P2 after the ship turns; T o ' ther (i) represents the time difference between the i-th time synchronization point of the other ship and the initial position of the other ship; t represents the initial time; t other0 Indicates the initial time of the other ship.

[0114] Suppose the new course of the ship after adjustment is cog' self , speed self The following calculations of the ship's position will be based on P2. Assume that the longitude and latitude coordinates of P2 are (lon self_2 ,lat self_2 ), assuming that the starting point of the turning point P2 is the i-th p2 If there is a time synchronization point, then after the heading adjustment, that is, the time synchronization point after the turning starting point P2, the calculation formula for the latitude and longitude coordinates of the ship's position is as follows:

[0115]

[0116] Where: (lon' selfi ,lat' selfi ) represents the latitude and longitude coordinates of the ship at the ith time synchronization point after turning; R is the radius of the earth, which is about 6371 kilometers;

[0117] Assuming that the other ships maintain their original speed and heading, the longitude and latitude coordinates of the i-th time synchronization point of the other ships are (lon otheri ,lat otheri ), the calculation formula of the latitude and longitude coordinates of the other ship can refer to the formula described in S22;

[0118] According to the latitude and longitude coordinates of the ship (lon' selfi ,lat' selfi ) and the longitude and latitude coordinates of other ships (lon otheri ,lat otheri ) calculates the distance between the corresponding position points of the own ship and other ships during the detour phase, and the calculation formula of the corresponding position point distance is as follows:

[0119] d i '=R×acos(sin(lon' selfi )×sin(lon otheri )+

[0120] cos(lon' selfi )×cos(lon otheri )×cos(lat otheri -lat s ' elfi ))

[0121] Where: d' i represents the mutual distance between the ship and other ships at the ith time synchronization point in the orbiting phase; R is the radius of the earth, which is about 6371 kilometers;

[0122] S43: Determine the smooth detour angle: If the smooth passage condition is met, the specific heading angle is the turning angle that enables the ship to sail smoothly during the detour phase; if the smooth passage condition is not met, continue to perform step S42 until a steering angle that is determined to enable smooth navigation during the detour phase is found. In a specific embodiment of the present invention, the mutual distance d' between the ship and the other ship at all time synchronization points during the detour phase at a specific angle is obtained by calculation. i If the course is adjusted at a specific course angle of 15°+j*5°, j is an integer between 0 and 9, and the collision danger point between the ship and other ships is 0 within the next hour, then the course angle cog' self The steering angle is determined to be the one that can smoothly pass during the detour phase; otherwise, if the ship still has the risk of collision with other ships, the yaw amount will continue to be increased in the prescribed heading angle adjustment range by a step of 5° until the collision risk point of the ship and other ships is 0 within the next hour after the start of the heading adjustment; let the first heading angle that meets the conditions during the trial be cog' self0 , then it should satisfy the following relationship:

[0123]

[0124] Where: n represents the number of time synchronization points within 1 hour after the start of heading adjustment; d T Indicates the minimum safe distance of the ship; d' i is the distance between the corresponding position of own ship and other ships; cogself It is the heading angle in the latest AIS data of the ship;

[0125] S5: Calculation of regression point: After detouring in S4, determine the appropriate regression point range, perform regression process collision avoidance calculation on the points within the regression point range in turn, and use the two-way step method until a point that can avoid all other ships and return to the original channel safely is found, which is the regression point; specifically, the following steps are included:

[0126] S51: Determine the range of regression points: Determine the range of regression points: Select to perform route regression between half an hour and one hour after the start of the detour phase. The formula for taking the value of the regression point within the determined range of regression points is as follows:

[0127]

[0128] Where: p m It is the first time synchronization point half an hour after the start of the orbiting phase, that is, the first time synchronization point within the range of the return point; p n It is the last time synchronization point 1 hour before the start of the orbit phase, that is, the last time synchronization point within the range of the regression point; p x is the assumed regression point, p x In p m to p n Take values ​​between

[0129] S52: Regression process collision avoidance calculation: Regression process collision avoidance calculation refers to the process from p x The calculation process of returning to the original course by returning to the course according to a certain heading angle can bypass all dangerous ships smoothly. e is the farthest point in the original collision danger point set, that is, the last collision danger point; assuming that the ship attempts to return from the assumed regression point p described in S51 x To the farthest collision danger point A e +3 nautical miles after the first time synchronization point position regression, set p x The longitude and latitude coordinates of the px ,lat px ), A e The longitude and latitude coordinates of the first time synchronization point after +3 nautical miles are (lon ae+3 ,lat ae+3 ), then the own ship's return heading angle cog s " elf The calculation formula is as follows:

[0130]

[0131] Where: (lon px ,lat px ) is the assumed regression point p xLatitude and longitude coordinates; (lon ae+3 ,lat ae+3 ) is the farthest collision danger point A e +3 nautical miles after the first time synchronization point latitude and longitude coordinates, that is, the assumed regression point latitude and longitude coordinates; the assumed regression point p x is the new reference point of own ship, cog s " elf is the new heading angle of the own ship, and S21-S24 are executed to calculate and count the collision risk points between the own ship and other ships, so as to determine whether there is a collision risk with other ships during the return process of the own ship;

[0132] S53: Determine the regression point: Determine the regression point is to determine p based on the calculation results. x The process of determining whether a point is suitable as a regression point. The confirmation of the regression point adopts a two-way step calculation: First, assume that p x No change, assuming that the ship is at the last collision danger point A in the original channel e The first time synchronization point 3 nautical miles after ) to calculate whether the ship has a collision risk with other ships. If there is no collision risk in the regression process, then the regression point p can be assumed to be x That is the regression point P3; if p x arrive If there is a collision risk on the return route, then select the collision risk point A e The second time synchronization point 3 nautical miles later (denoted as ) to perform regression and calculate p x arrive Is the return route safe? There are m time synchronization points between P5 and the farthest point in the plan, so try to start from p x The route is returned to these m points until a safe return route is found; the farthest point in the plan is the position point corresponding to the ship sailing for 6 hours from the current time while maintaining the current state of the ship. The calculation formula is as follows:

[0133]

[0134] Where: c1, c2, ..., c m Indicates p x The number of collision danger points on the m regression routes to m time synchronization points respectively. Calculate from 1 to m in order from small to large, and the calculation formula of regression point P3 is as follows:

[0135] P3=p t (1≤t≤m,c t =0)

[0136] If from p xIf a smooth return route cannot be found at m time synchronization points, the detour route is p x Continue moving forward to p x+1 , repeat the above process to calculate p x+1 The regression line to m time-synchronized points on the original course is used to determine p x+1 Whether the regression condition is met. And so on, until the regression point P3 that meets the condition is finally found.

[0137] S6: Return point calculation: Determine the return point of the ship based on the return point confirmed in S5;

[0138] Specifically, the return point calculation is the process of calculating the position at which the ship returns to the original course, which mainly includes determining the return point of the ship to the original course; when determining the return point in S5, it is necessary to calculate the return point p of the detour route. x Point A is the farthest collision danger point from the original course e After adding 3 nautical miles to the farthest point P5 of this route planning, multiple attempts are made between the m assumed return points, and finally p is determined. x →p t is a safe return route with a collision risk point of 0. Assuming P4 is the return landing point, the calculation formula for the return landing point is:

[0139] P4=p t

[0140] P4=p t

[0141] Where: p t Indicates safe return to the landing point corresponding to the original route;

[0142] S7: Determine the new route: Determine the new route of the ship by connecting the five points based on the current position of the ship, the turning starting point calculated by S3, the return point calculated by S5, the return landing point calculated by S6 and the farthest point of the route planning;

[0143] Specifically, the new route determination is the process of finally determining a new route based on the above calculation results, which mainly includes five points to determine the new route; as mentioned above, this embodiment has determined the current position P1 of the ship, the turning point P2, the regression point P3, the regression landing point P4 and the planned farthest point P5, and the route planning is carried out in a straight line manner. Therefore, the new route is obtained by directly connecting the five points.

[0144] The second group of embodiments, an automatic route planning system for avoiding collisions between AIS groups of ships

[0145] This group of embodiments provides an automatic planning system for ship collision avoidance routes based on AIS, the system comprising an AIS data acquisition and analysis module connected in sequence for acquiring AIS original message data of a ship on the water and parsing it 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 according to the ship AIS data acquired by the AIS data acquisition and analysis module and constructing a collision danger point set, a turning starting point calculation module for calculating the turning starting point according to the distance between the corresponding position point of the nearest collision danger point and the current position of the ship, a steering angle calculation module for using a trial method to find a steering angle that can meet the smooth navigation conditions within the heading angle adjustment range, a regression point calculation module for using a two-way step method to calculate the regression point within the regression point range, 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 five points of 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 to obtain the new route of the ship;

[0146] The route collision danger point calculation and statistics module calculates multiple time points in the future based on the ship AIS data obtained by the AIS data collection and analysis module, taking the current time as the reference and the preset time period as the time interval, and calculates the corresponding position point distances between the own ship and other ships corresponding to the multiple time points according to the multiple time points, and counts the collision danger points of the own ship and other ships according to the corresponding position point distances, and constructs a collision danger point set;

[0147] The steering angle calculation module determines the heading angle adjustment range, uses the trial method to perform step-by-step trial calculation at the steering starting point calculated by the steering starting point calculation module, and increases the heading angle from small to large according to a specific step length according to the heading angle adjustment range, and uses the route collision danger point calculation and statistics module to perform collision danger point statistics until a detour angle that satisfies the smooth passage of the ship in the future is found, and the detour is performed according to the detour angle; the smooth passage means that the number of collision danger points is 0;

[0148] After the trial method steering angle calculation module determines the detour, the regression point calculation module determines the appropriate regression point range, performs regression process collision avoidance calculation on the points within the regression point range in turn, and uses the two-way step method to calculate until a point that can avoid all other ships and return to the original course safely is found, which is the regression point.

Claims

1. A method for automatic planning of collision avoidance routes for groups of ships based on AIS, characterized in that: The steps include: S1: AIS data collection and analysis: obtaining the AIS original message data of the ship at sea, and analyzing the AIS original message data to obtain the ship AIS data; S2: Calculation and statistics of route collision danger points: Based on the ship AIS data obtained in S1, multiple time points in the future are calculated with the current time as the reference and the preset time period as the time interval, and the corresponding position point distances between the own ship and other ships corresponding to the multiple time points are calculated according to the multiple time points, and the collision danger points of the own ship and other ships are counted according to the corresponding position point distances, and a collision danger point set is constructed; S3: Calculation of the starting point of turning: Select the nearest collision danger point from the set of collision danger points constructed in S2, and calculate the starting point of turning according to the distance between the nearest collision danger point and the corresponding position point of the current position of the ship; S4: Calculation of steering angle by heuristic method: Determine the adjustment range of the heading angle, perform step-by-step heuristic calculation using the heuristic method at the turning starting point described in S3, increase the heading angle from small to large according to a specific step length according to the adjustment range of the heading angle, and execute step S2 until a detour angle that satisfies the smooth passage of the ship in the future is found, and the ship detoured according to the detour angle; S5: Calculation of regression point: After detouring in S4, determine the appropriate regression point range, perform regression process collision avoidance calculation on the points within the regression point range in turn, and use the two-way step method to calculate until a point that can avoid all other ships and return to the original course safely is found, which is the regression point; S6: Return point calculation: Determine the return point of the ship based on the return point confirmed in S5; S7: Determine the new route: Determine the new route of the ship by connecting the five points based on the current position of the ship, the turning starting point calculated by S3, the return point calculated by S5, the return landing point calculated by S6 and the farthest point of the route planning.

2. The method for automatic planning of a group ship collision avoidance route based on AIS according to claim 1, characterized in that: The ship at sea described in S1 is a ship equipped with a shipborne automatic identification system. The specific process of AIS data collection and analysis is as follows: an AIS isolation distributor connected to the shipborne automatic identification system is installed on the ship at sea, and is connected to a serial port server, a switch and an analysis server in sequence; the shipborne automatic identification system is responsible for receiving various AIS broadcast signals of all ships within the effective range around the ship, and providing an external interface, and through the AIS isolation distributor, synchronously and parallelly outputting one signal to the serial port server, the serial port server converts the AIS broadcast signal in serial port format into a network signal and then connects it to the switch, and then connects the network signal to the analysis server for decoding and parsing to obtain the ship AIS data.

3. The method for automatic planning of a group ship collision avoidance route based on AIS according to claim 2, characterized in that: The AIS original message data is transmitted using compressed ASCII code, complies with the NMEA0183 protocol, and is divided into plain text and coded text; therefore, the decoding and parsing of the network signal by the analysis server is to parse the A and B class messages starting with "!AIVDM", and extract the ship's position information, navigation dynamics and static parameters from them; the navigation dynamics and static parameters include MMSI, ship name, heading and speed.

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

5. The method for automatic route planning based on AIS group ship collision avoidance according to claim 4 is characterized in that: S2 specifically includes the following steps: S21: Time synchronization between the ship and other ships: taking the current time as the reference point and the preset time period as the time interval, multiple time points within a period of time in the future are calculated, and the time difference between the multiple time points and the time in the latest AIS data of the ship and other ships is calculated. The multiple 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 other ships is calculated as follows: Where: T self (i) represents the time difference between the ith time synchronization point and the time in the latest AIS data of the own ship; t self0 Indicates the time of the latest AIS data of this ship; T other (i) represents the time difference between the ith time synchronization point and the time in the latest AIS data of other ships; t other0 Indicates the time in the latest AIS data of other ships; t indicates the current time; S22: Synchronize the future time positions of own ship and other ships: Based on the time synchronization in S21, assuming that all ships keep their current status unchanged, the heading angle, speed, longitude and latitude coordinates of own ship and other ships corresponding to multiple time synchronization points in S21 are calculated according to the heading angle, speed, longitude and latitude coordinates of the latest ship AIS data collected in step S1 at the current time; The calculation formula of the latitude and longitude coordinates of the ship is as follows: Where: (lon selfi ,lat selfi ) represents the latitude and longitude coordinates of the ship at the ith time synchronization point; T self (i) represents the time difference between the ith time synchronization point and the time in the latest AIS data of the ship; (lon self0 ,lat self0 )、sog self 、cog self They represent the latitude and longitude coordinates, speed, and heading angle of the latest AIS data of the ship; R represents the radius of the earth; The calculation formula of the latitude and longitude coordinates of the other ship is as follows: Where: (lon otheri ,lat otheri ) represents the longitude and latitude coordinates of the other ship at the ith time synchronization point; T other (i) represents the time difference between the ith time synchronization point and the time in the latest AIS data of other ships; (lon other0 ,lat other0 )、sog other 、cog other They represent the latitude and longitude coordinates, speed, and heading angle of the other ship’s latest AIS data; R represents the radius of the earth; S23: Calculate the distance between corresponding position points: Use the longitude and latitude coordinates of the own ship and the other ship in S22 to calculate the mutual distance between the own ship and the other ship corresponding to multiple time synchronization points, and obtain multiple corresponding position point distances between the own 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 )、(lon otheri ,lat otheri ) represent the longitude and latitude coordinates of the i-th time synchronization point of the own ship and other ships respectively; R is the radius of the earth; S24: Calculation and statistics of collision risk points: Determine the minimum safe distance based on the rules for avoiding collisions between ships at sea. If the distance between the corresponding position points in S23 is less than the minimum safe distance, it is determined that there is a risk of collision between the other ship and the own ship, and the time and position when there is a risk of collision are recorded, and the number of risk of collision is counted. The calculation formula is as follows: Where: n represents the number of all time synchronization points in the future time; d T Indicates the minimum safe distance of the ship; d i represents the distance between the corresponding position points of the ship and other ships at the i-th time synchronization point; 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 danger point set, which includes the time, position and corresponding position point distance corresponding to each collision danger point.

6. The method for automatic planning of a group ship collision avoidance route based on AIS according to claim 5, characterized in that: S3 includes the following steps: S31: Determine 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, that is, the point with the shortest time; S32: Calculation of the starting point of turning: Substitute the time, position, speed and heading angle in the latest AIS data of the ship into the formula described in S21-S22 to calculate the longitude and latitude coordinates of the current position of the ship; Substitute the longitude and latitude coordinates of the current position of the ship and the nearest collision danger point into the formula described in S23 to calculate the distance between the corresponding position points of the ship and the nearest collision danger point; if the distance between the corresponding position points of the current position of the ship and the nearest collision danger point is less than or equal to 3 nautical miles, the current position of the ship is the starting point of the turning for this route planning; otherwise, the ship continues to sail along the original route, and adjusts the course when the distance to the nearest collision danger point is less than or equal to 3 nautical miles, and the point where the course adjustment begins is the starting point of the turning.

7. The method for automatic planning of a group ship collision avoidance route based on AIS according to claim 5, characterized in that: S4 includes the following steps: S41: Determine the heading angle adjustment range: set the heading angle adjustment range and step length according to relevant requirements and rules, start from 15 degrees, and conduct a tentative route exploration with a step length of 5 degrees. The maximum adjustment angle is set to a 60 degree deflection angle; S42: Step-by-step trial calculation: Use the trial method to start step-by-step route exploration from the minimum heading angle in the heading angle adjustment range; perform steps S21-S24 for the own ship sailing along a specific heading angle to calculate and count the collision risk points between the own ship and other ships, and judge whether the smooth navigation conditions of the own ship in the detour phase are met according to the number of collision risk 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 ship starts to adjust the heading at the turning starting point; the detour phase is the phase in which the own ship sails along a specific heading angle; S43: Determine the smooth detour angle: If the smooth passage condition is met, the specific heading angle is the turning angle that enables the ship to navigate smoothly during the detour stage; if the smooth passage condition is not met, continue with step S42 until a steering angle that enables smooth navigation during the detour stage is found.

8. The method for automatic planning of a group ship collision avoidance route based on AIS according to claim 7, characterized in that: S5 includes the following steps: S51: Determine the range of regression points: Select to perform route regression between half an hour and one hour after the start of the detour phase. The regression point is taken within the determined range of regression points. The formula is as follows: Where: p m is the first time synchronization point within the range of regression points; p n is the last time synchronization point within the regression point range; p x is the assumed regression point, assuming the regression point p x In order in p m to p n Take values ​​between S52: Collision avoidance calculation in regression process: Assume A e is the farthest point in the original collision danger point set, that is, the last collision danger point; assuming that the ship attempts to return from the assumed regression point p described in S51 x To the farthest collision danger point A e +3 nautical miles after the first time synchronization point position returns, then the ship returns to the heading angle cog s " elf The calculation formula is as follows: Where: (lon px ,lat px ) is the assumed regression point p x Latitude and longitude coordinates; (lon ae+3 ,lat ae+3 ) is the farthest collision danger point A e +3 nautical miles after the first time synchronization point latitude and longitude coordinates, that is, the assumed regression point latitude and longitude coordinates; the assumed regression point p x is the new reference point of own ship, cog s " elf is the new heading angle of the own ship, and S21-S24 are executed to calculate and count the collision risk points between the own ship and other ships, so as to determine whether there is a collision risk with other ships during the return process of the own ship; S53: Determine the regression point: The regression point is confirmed by a two-way stepping method, as follows: Assuming that there is no collision risk during the S52 regression process, p can be determined. x is the regression point; if there is a collision risk in the regression process, then select A e The ship returns to the second time synchronization point 3 nautical miles away and repeats S21-S24 to determine whether there is a risk of collision with other ships during the return process. Similarly, assuming that A e If there are m time synchronization points between the last 3 nautical miles and the farthest point of the route planning, try to start from p in turn. x Perform route regression to the position points corresponding to the m time synchronization points until a route without collision risk is found; if not found, then take a detour route p x Continue moving forward to p x+1 , repeat the above process to calculate p x+1 The regression line to m time-synchronized points on the original course is used to determine p x+1 Whether the regression conditions are met; and so on, until a regression point that meets the conditions is finally found.

9. The method for automatic planning of a group ship collision avoidance route based on AIS according to claim 8, characterized in that: The return point in S6 is the point where the route without collision risk found in steps S52-S53 intersects with the original route, that is, the return point.

10. An automatic planning system for ship collision avoidance routes based on AIS, characterized in that: It includes an AIS data acquisition and analysis module connected in sequence for acquiring AIS original message data of a ship at sea and analyzing it 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 according to the ship AIS data acquired by the AIS data acquisition and analysis module and constructing a collision danger point set, a turning starting point calculation module for calculating the turning starting point according to the distance between the corresponding position point of the nearest collision danger point and the current position of the ship, a steering angle calculation module for using a trial method to find a steering angle that can meet the conditions of smooth navigation within the heading angle adjustment range, a regression point calculation module for using a two-way step method to calculate the regression point within the regression point range, 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 five points of 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 to obtain the new route of the ship; The route collision danger point calculation and statistics module calculates multiple time points in the future based on the ship AIS data obtained by the AIS data collection and analysis module, taking the current time as the reference and the preset time period as the time interval, and calculates the corresponding position point distances between the own ship and other ships corresponding to the multiple time points according to the multiple time points, and counts the collision danger points of the own ship and other ships according to the corresponding position point distances, and constructs a collision danger point set; The steering angle calculation module determines the heading angle adjustment range, uses the trial method to perform step-by-step trial calculation at the steering starting point calculated by the steering starting point calculation module, and increases the heading angle from small to large according to a specific step length according to the heading angle adjustment range, and uses the route collision danger point calculation and statistics module to perform collision danger point statistics until a detour angle that satisfies the smooth passage of the ship in the future is found, and the detour is performed according to the detour angle; the smooth passage means that the number of collision danger points is 0; After the trial method steering angle calculation module determines the detour, the regression point calculation module determines the appropriate regression point range, performs regression process collision avoidance calculation on the points within the regression point range in turn, and uses the two-way step method to calculate until a point that can avoid all other ships and return to the original course safely is found, which is the regression point.

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