Ship encounter space-time risk degree assessment method and system considering influence of navigation environment

Abstract

The invention discloses a ship encounter space-time risk assessment method and system considering navigation environment influence, and belongs to the technical field of ship safe driving. The invention aims to solve the problem that the collision avoidance action opportunity of a complex marine environment collision avoidance scene cannot be accurately determined. According to the invention, through a ship environment sensing module and a positioning module, channel environment information of a ship navigation area and position, course and speed information of a ship are obtained; calculating the nearest meeting distance of the intersection of the two ships, the meeting time of the ships sailing from the current position to the nearest intersection of the two ships, the safe meeting distance of the two ships, the absolute safe meeting distance, the latest avoiding distance and the distance capable of taking measures for avoiding; calculating the collision danger degree in the spatial position and the collision danger degree of the two ships in the time dimension; combining the space risk factor and the time risk factor by using a synthesis operator, and calculating the space-time collision risk factor; and evaluating the risk degree of ship collision according to the risk degree. The method is suitable for ship encounter space-time risk assessment.

Description

Technical Field

[0001] The invention belongs to the technical field of safe ship driving. Background Art

[0002] Although the capabilities of navigation instruments and equipment for safe navigation of ships are constantly improving, the technical means of preventing collisions of ships are constantly improving, and even the International Maritime Organization resolution requires ships to be equipped with AIS automatic identification systems, the problem of ship collisions still exists. By using these devices, ships can accurately obtain the position, heading, and speed information of their own ships, and it is also easy to obtain relevant information of other ships. However, due to the influence of regional structure, dynamic characteristics of ships and bad weather affecting maritime traffic, the timing of collision avoidance actions taken by ships during navigation still depends largely on the subjective judgment of the driver, and there are greater collision avoidance risks and safety hazards.

[0003] The document "Calculation of Ship Composite Collision Risk Based on Fuzzy Theory" proposes a method for calculating the ship composite collision risk. The algorithm is based on the concepts of ship domain and dynamic domain. On the basis of the ship collision geometry principle, it uses fuzzy rules and fuzzy comprehensive evaluation methods to judge the ship collision risk. However, this method does not consider the timing of the action that the ship should take when the risk changes.

[0004] The document "Ship Collision Avoidance Comprehensive Decision System" studies the collision avoidance behavior of ships and the thinking process of collision avoidance decision-making for multiple ships and multiple criteria. It applies the theory of marine traffic engineering and fuzzy set theory to establish a ship collision avoidance comprehensive decision-making model for multiple objects and multiple criteria. However, the algorithm does not take into account the impact of the size of the navigable area and weather changes on ship collision avoidance decisions.

[0005] The document "Construction of Ship Collision Risk Model" establishes a mathematical model for determining the collision risk between ships based on the concept of "domain" and fuzzy principle. This model not only comprehensively considers the impact of multiple factors on the collision risk, but is also simple and easy to implement. However, this method also does not consider the impact of the collision risk on the timing of taking collision avoidance actions.

[0006] Some of the above literatures do not consider the impact of the risk of ship collision on the timing of the ship's collision avoidance action, and some do not consider the impact of weather factors and the size of the navigable area on the risk of ship collision. However, in actual navigation, ships often face more complex and dangerous collision avoidance scenarios. There are various factors that affect the risk of ship collision and interfere with the driver's judgment on the timing of taking collision avoidance actions, resulting in the problem of unclear timing of taking collision avoidance actions during the ship's collision avoidance process. Summary of the invention

[0007] The present invention aims to solve the problem that the timing of collision avoidance action in a complex marine environment collision avoidance scenario cannot be accurately determined. A method and system for assessing the temporal and spatial hazard of ship encounters taking into account the influence of the navigation environment are provided.

[0008] The method for assessing the temporal and spatial risk of a ship considering the impact of the navigation environment of the present invention comprises:

[0009] Step 1: Obtain the channel environment information of the ship's navigation area and the ship's own position, heading and speed information through the ship environment perception module and positioning module;

[0010] Step 2: Calculate the closest encounter distance DCPA and the encounter time TCPA from the current position of the ship to the closest intersection point of the two ships based on the channel environment information in the navigable area and the ship's own position, heading and speed information;

[0011] According to the channel environment information in the navigable area and the ship's own position, heading and speed information, the safe encounter distance d1, the absolutely safe encounter distance d2, the latest avoidance distance D1 and the avoidance distance D2 that can be avoided by taking measures are calculated;

[0012] Step 3: Using the distance and time calculated in step 2, calculate the collision risk level SCRI in spatial position and the collision risk level TCRI between the two ships in time dimension;

[0013] Step 4: Use the synthesis operator to combine the spatial risk index SCRI and the temporal risk index TCRI to calculate the spatiotemporal collision risk index STCRI;

[0014] Step 5: Evaluate the risk of ship collision based on the spatial risk index SCRI, temporal risk index TCRI and spatiotemporal collision risk index STCRI.

[0015] Furthermore, in the present invention, in step one, the waterway environment information includes the position, heading, speed, range of the navigable area and weather condition information of the navigable vessels around the ship.

[0016] The scope of the navigable area includes the width of the river, the width of the port, etc.

[0017] Furthermore, in the present invention, in step 2, the closest encounter distance DCPA of the two ships is:

[0018]

[0019] Where V0 is the speed of the ship; V t for the speed of his ship; is the heading angle of own ship; is the heading angle of the other ship; θ is the azimuth of the other ship relative to our ship; r is the relative distance between the other ship and our ship.

[0020] Furthermore, in the present invention, in step 2, the encounter time TCPA of the ship sailing from the current position to the closest intersection point of the two ships is:

[0021]

[0022] Furthermore, in the present invention, in step 2, the safe encounter distance d1 and the absolutely safe encounter distance d2 of the two ships are respectively:

[0023]

[0024] d2=K1·d1

[0025] Where W is the channel width; D is the ship width; E is the current visibility; L is the ship length; R is the distance between the two ships; V r It is the relative speed of the two ships. K1 represents the distance expansion coefficient caused by the adverse environment. It is determined by factors such as the instability of the ship status, the uncoordinated actions of the two ships, and the error of the equipment. The value range is 3 to 5.

[0026] Furthermore, in the present invention, in step 2, the latest avoidance distance D1 and the avoidance distance D2 that can be avoided are respectively:

[0027]

[0028] D2=K2·D1

[0030] Furthermore, in the present invention, in step 3, the collision risk level SCRI in the spatial position is:

[0031]

[0032] Furthermore, in the present invention, in step 3, the collision risk level TCRI of the two ships in the time dimension is:

[0033]

[0034] Furthermore, in the present invention, in step 4, the spatiotemporal collision risk STCRI is:

[0035]

[0036] In the formula, is a synthesis operator, and the specific synthesis rules are:

[0037] (1) If SCRI is 0, then STCRI is 0;

[0038] (2) If SCRI is not 0 and TCRI is 0, then STCRI is 0;

[0039] (3) If both SCRI and TCRI are not 0, then STCRI is the larger value of SCRI and TCRI.

[0040] Furthermore, in the present invention, in step 5, the method for evaluating the risk of ship collision is:

[0041] When SCRI = 0, there is no risk of collision between the two ships;

[0042] When SCRI>0 and STCRI=0, the risk of collision between the two ships will begin to occur; the give-way ship needs to take collision avoidance actions according to the International Regulations for Preventing Collisions at Sea;

[0043] When STCRI>0, the risk of collision is increasing, and the give-way vessel still needs to take action to avoid collision, while the straight-line vessel is allowed to take collision avoidance action to avoid collision;

[0044] When STCRI=0 or the rate of change of TCRA is greater than 0, the collision avoidance risk gradually decreases.

[0045] A ship encounter time-space risk assessment system considering the impact of the navigation environment, including a data acquisition module, an encounter collision parameter calculation module, a collision risk calculation module, and a ship collision risk assessment module;

[0046] The data acquisition module is used to obtain the channel environment information of the ship's navigation area and the ship's own position, heading and speed information through the ship environment perception module and the positioning module;

[0047] The collision parameter calculation module is used to calculate the closest encounter distance DCPA of the two ships and the encounter time TCPA from the current position of the ship to the closest intersection point of the two ships according to the channel environment information in the navigable area and the ship's own position, heading and speed information;

[0048] The collision parameter calculation module is also used to calculate the safe encounter distance d1, the absolute safe encounter distance d2, the latest avoidance distance D1 and the avoidance distance D2 that can be avoided based on the channel environment information in the navigable area and the ship's own position, heading and speed information;

[0049] The collision risk calculation module is used to calculate the collision risk level SCRI in the spatial position and the collision risk level TCRI of the two ships in the time dimension by using the distance and time calculated in step 2 and step 3;

[0050] The ship collision risk assessment module is used to assess the risk of ship collision based on the spatial risk index SCRI, the temporal risk index TCRI and the spatiotemporal collision risk index STCRI.

[0051] The method and system disclosed in the present invention face more complex and dangerous collision avoidance scenarios during actual navigation. Although the COLREGs Rules stipulate basic ship collision avoidance requirements and specifications, it still does not clearly explain when the collision risk occurs and when the encountering ships take collision avoidance and homing actions. The present invention designs a safe encounter distance, a latest collision avoidance distance and a synthesis operator, etc., to calculate a more accurate spatiotemporal collision risk and judge the action that the ship should take according to its size and change law, thereby solving the problems of inaccurate collision risk and unclear timing of collision avoidance behavior during collision avoidance, and improving the collision avoidance efficiency and navigation safety during ship navigation. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 is a flow chart of the method of the present invention;

[0053] Figure 2 It is a schematic diagram of the minimum encounter distance and minimum encounter time of ships;

[0054] Figure 3 It is a schematic diagram of safe encounter distance, absolutely safe encounter distance, latest avoidance distance and avoidance distance that can be avoided by taking measures;

[0055] Figure 4 It is a system diagram of the present invention. DETAILED DESCRIPTION

[0056] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0057] Specific implementation method 1: Referring to FIG. Figures 1 to 3 Specifically describing this embodiment, the method for assessing the temporal and spatial risk of a ship encountering considering the influence of the navigation environment described in this embodiment includes:

[0058] Step 1: Obtain the channel environment information of the ship's navigation area and the ship's own position, heading and speed information through the ship environment perception module and positioning module;

[0059] Step 2: Calculate the closest encounter distance DCPA and the encounter time TCPA from the current position of the ship to the closest intersection point of the two ships based on the channel environment information in the navigable area and the ship's own position, heading and speed information;

[0060] According to the channel environment information in the navigable area and the ship's own position, heading and speed information, the safe encounter distance d1, the absolutely safe encounter distance d2, the latest avoidance distance D1 and the avoidance distance D2 that can be avoided by taking measures are calculated;

[0061] Step 3: Using the distance and time calculated in step 2, calculate the collision risk level SCRI in spatial position and the collision risk level TCRI between the two ships in time dimension;

[0062] Step 4: Use the synthesis operator to combine the spatial risk index SCRI and the temporal risk index TCRI to calculate the spatiotemporal collision risk index STCRI;

[0063] Step 5: Evaluate the risk of ship collision based on the spatial risk index SCRI, temporal risk index TCRI and spatiotemporal collision risk index STCRI.

[0064] Furthermore, in the present invention, in step one, the waterway environment information includes the position, heading, speed, range of the navigable area and weather condition information of the navigable vessels around the ship.

[0065] The scope of the navigable area includes the width of the river, the width of the port, etc.

[0066] Furthermore, in the present invention, in step 2, the closest encounter distance DCPA of the two ships is:

[0067]

[0068] Where V0 is the speed of the ship; V t for the speed of his ship; is the heading angle of own ship; is the heading angle of the other ship; θ is the azimuth of the other ship relative to our ship; r is the relative distance between the other ship and our ship.

[0069] Furthermore, in the present invention, in step 2, the encounter time TCPA of the ship sailing from the current position to the closest intersection point of the two ships is:

[0070]

[0071] Furthermore, in the present invention, in step 2, the safe encounter distance d1 and the absolutely safe encounter distance d2 of the two ships are respectively:

[0072]

[0073] d2=K1·d1

[0074] Where W is the channel width; D is the ship width; E is the current visibility; L is the ship length; R is the distance between the two ships; V r It is the relative speed of the two ships. K1 represents the distance expansion coefficient caused by the adverse environment. It is determined by factors such as the instability of the ship status, the uncoordinated actions of the two ships, and the error of the equipment. The value range is 3 to 5.

[0075] Furthermore, in the present invention, in step 2, the latest avoidance distance D1 and the avoidance distance D2 that can be avoided are respectively:

[0076]

[0077] D2=K2·D1

[0079] Furthermore, in the present invention, in step 3, the collision risk level SCRI in the spatial position is:

[0080]

[0081] Furthermore, in the present invention, in step 3, the collision risk level TCRI of the two ships in the time dimension is:

[0082]

[0083] Furthermore, in the present invention, in step 4, the spatiotemporal collision risk STCRI is:

[0084]

[0085] In the formula, is a synthesis operator, and the specific synthesis rules are:

[0086] (1) If SCRI is 0, then STCRI is 0;

[0087] (2) If SCRI is not 0 and TCRI is 0, then STCRI is 0;

[0088] (3) If both SCRI and TCRI are not 0, then STCRI is the larger value of SCRI and TCRI.

[0089] Furthermore, in the present invention, in step 5, the method for evaluating the risk of ship collision is:

[0090] When SCRI = 0, there is no risk of collision between the two ships;

[0091] When SCRI>0 and STCRI=0, the risk of collision between the two ships will begin to occur; the give-way ship needs to take collision avoidance actions according to the International Regulations for Preventing Collisions at Sea;

[0092] When STCRI>0, the risk of collision is increasing, and the give-way vessel still needs to take action to avoid collision, while the straight-line vessel is allowed to take collision avoidance action to avoid collision;

[0093] When STCRI=0 or the rate of change of TCRA is greater than 0, the collision avoidance risk gradually decreases.

[0094] A ship encounter time-space risk assessment system considering the impact of the navigation environment, comprising a data acquisition module (1), an encounter collision parameter calculation module (2), a collision risk calculation module (3), and a ship collision risk assessment module (4);

[0095] The data acquisition module (1) is used to obtain the channel environment information of the ship's navigation area and the ship's own position, heading and speed information through the ship environment perception module and the positioning module;

[0096] The encounter and collision parameter calculation module (2) is used to calculate the closest encounter distance DCPA of the two ships and the encounter time TCPA from the current position of the ship to the closest intersection point of the two ships according to the channel environment information in the navigable area and the position, heading and speed information of the ship itself;

[0097] The collision parameter calculation module is also used to calculate the safe encounter distance d1, the absolute safe encounter distance d2, the latest avoidance distance D1 and the avoidance distance D2 that can be avoided based on the channel environment information in the navigable area and the ship's own position, heading and speed information;

[0098] The collision risk calculation module (3) is used to calculate the collision risk level SCRI in the spatial position and the collision risk level TCRI of the two ships in the time dimension by using the distance and time calculated in step 2 and step 3;

[0099] The ship collision risk assessment module (4) is used to assess the risk of ship collision based on the spatial risk SCRI, the temporal risk TCRI and the spatiotemporal collision risk STCRI.

[0100] Specific real-time processes for risk avoidance methods include:

[0101] 1. Obtain the channel environment information of the ship's navigation area and its own position, heading and speed information. The ship is equipped with marine environment perception modules such as navigation radar system, satellite positioning navigation system, AIS ship automatic identification system, laser radar and binocular vision system, which can obtain the channel environment information around the ship and its own position, heading and speed information in real time;

[0102] The above-mentioned channel environment information refers to the position, course, speed information, range information of the navigable area and weather conditions of other navigable vessels around the ship.

[0103] 2. Calculate the closest approach distance DCPA of the two ships and the closest approach time TCPA from the current position of the ship to the intersection of the two ships.

[0104]

[0105]

[0106] Where V0 is the speed of the ship; V t for the speed of his ship; is the heading angle of own ship; is the heading angle of the other ship; θ is the azimuth of the other ship relative to our ship; r is the relative distance between the other ship and our ship.

[0107] 3. Calculate the safe meeting distance d1, the absolutely safe meeting distance d2, the latest avoidance distance D1 and the avoidance distance D2 that can be avoided.

[0108]

[0109] d2=K1·d1

[0110]

[0111] D2=K2·D1

[0112] Where W is the channel width; D is the ship width; E is the current visibility; L is the ship length; R is the distance between the two ships; V r is the relative speed of the two ships, V is the speed of the own ship. K1 and K2 represent the distance expansion coefficient caused by the adverse environment, which is determined by factors such as the instability of the ship state, the uncoordinated actions of the two ships, and the error of the equipment, and is generally 3 to 5.

[0113] 4. Calculate the collision risk level SCRI of the two ships in spatial position and the collision risk level TCRI of the two ships in time dimension.

[0114] SCRI represents the degree of danger of the two ships in space, and its mathematical expression is:

[0115]

[0116] Where d1 is the safe meeting distance of ships, and d2 is the absolutely safe meeting distance.

[0117] TCRI represents the degree of danger between two ships in the time dimension, and its mathematical expression is:

[0118]

[0119] Where V r is the relative speed of the other ship to this ship, D1 is the latest avoidance distance, and D2 is the distance at which avoidance measures can be taken.

[0120] 5. Design a synthesis operator to combine the spatial risk index SCRI and the temporal risk index TCRI to calculate the space-time collision risk index STCRI

[0121] By combining SCRI and TCRI, the space-time collision risk STCRI can be obtained. The combination method is as follows:

[0122]

[0123] In the formula, is a composite operator, and its specific composite rule is:

[0124] (1) If SCRI is 0, then STCRI is 0;

[0125] (2) If SCRI is not 0 and TCRI is 0, then STCRI is 0;

[0126] (3) If both SCRI and TCRI are not 0, then STCRI is the larger value of SCRI and TCRI.

[0127] 6. Based on the calculated spatial risk index SCRI, temporal risk index TCRI and space-time collision risk index STCRI, determine what actions the ship should take in the situation.

[0128] When SCRI = 0, there is no risk of collision between the two ships, and each ship is free to take action.

[0129] When SCRI>0 and STCRI=0, the risk of collision begins to arise. According to the COLREGs Rules, the give-way vessel takes collision avoidance action.

[0130] When STCRI>0, the collision risk is high and the collision avoidance situation is urgent. The give-way vessel should still take action to avoid collision, but the straight-line vessel is allowed to take collision avoidance action to avoid collision.

[0131] When STCRI = 0 or the rate of change of TCRA is greater than 0, the collision avoidance risk gradually disappears and the homing action can be performed.

[0132] Method for judging the temporal and spatial danger of ship encounter situations,

[0133] The system comprises:

[0134] (1) Information data processing module: transmits the channel environment information of the ship's navigation area, receives mission information, and processes and optimizes various types of data. It regularly updates the channel environment information and provides the collision risk assessment module with time-varying channel environment information as well as the ship's current position, speed and heading information.

[0135] The above-mentioned channel environment information refers to the position, speed and heading information of other navigable vessels around the ship and the scope information of the navigable area.

[0136] (2) Collision risk assessment module: Based on the received mission instructions and the current status information of the own ship, the status information of other ships, and the weather and channel information, the closest approach distance DCPA and the closest approach time TCPA are calculated to generate the spatial risk index SCRI and the temporal risk index TCRI. The spatiotemporal collision risk index STCRI is obtained through the synthesis operator. Based on the information transmitted by the information data processing module, the SCRI, TCRI and STCRI are updated regularly, and the collision risk and whether the own ship should take collision avoidance actions are judged based on the relevant collision risk index.

[0137] The collision risk assessment module continuously provides the latest time-space collision risk and collision avoidance action reminders based on updated channel environment information and the real-time status of the own ship and other ships.

[0138] A ship encounter time-space risk assessment system considering the impact of the navigation environment, comprising a data acquisition module 1, an encounter collision parameter calculation module 2, a collision risk calculation module 3, and a ship collision risk assessment module 4;

[0139] The data acquisition module 1 is used to obtain the channel environment information of the ship's navigation area and the ship's own position, heading and speed information through the ship environment perception module and the positioning module;

[0140] Environmental perception module: Through navigation radar and AIS ship automatic identification system, the ship can obtain the information of navigable ships around the ship and the navigable area of ​​the channel; the AIS ship automatic identification system can automatically exchange important information such as ship position, speed, heading, ship name, call sign, etc. with other ships. For some small ships that cannot install large environmental perception modules such as navigation radar, sensors such as laser radar and binocular vision system can be used instead of navigation radar.

[0141] Positioning module: obtains the ship's position, speed and heading information through Beidou integrated device and integrated navigation, transmits it to the information data processing module, and provides the collision risk assessment module with time-varying ship status information;

[0142] Navigable ships: receive evasive action instructions, execute control mechanisms, and navigate according to prescribed instructions.

[0143] The collision parameter calculation module 2 is used to calculate the closest encounter distance DCPA of the two ships and the encounter time TCPA from the current position of the ship to the closest intersection point of the two ships according to the channel environment information in the navigable area and the position, heading and speed information of the ship itself;

[0144] The collision parameter calculation module is also used to calculate the safe encounter distance d1, the absolute safe encounter distance d2, the latest avoidance distance D1 and the avoidance distance D2 that can be avoided based on the channel environment information in the navigable area and the ship's own position, heading and speed information;

[0145] The collision risk calculation module 3 is used to calculate the collision risk level SCRI in the spatial position and the collision risk level TCRI of the two ships in the time dimension by using the distance and time calculated in step 2 and step 3;

[0146] The ship collision risk assessment module 4 is used to assess the risk of ship collision according to the spatial risk SCRI, the temporal risk TCRI and the spatiotemporal collision risk STCRI.

[0147] The environmental perception module of the present invention obtains the channel environment information of the sea area where the transmitting ship is sailing, receives the mission information, and processes and optimizes various data, regularly updates the channel environment information, and provides the collision risk assessment module with the time-varying channel environment information and the current position, speed and heading information of the ship. The channel environment information refers to the position, speed and heading information of other navigable ships around the ship and the range information of the navigable area.

[0148] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. It should therefore be understood that many modifications may be made to the exemplary embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in a manner different from that described in the original claims. It should also be understood that the features described in conjunction with a single embodiment may be used in other described embodiments.

Claims

1. A method for assessing the temporal and spatial risk of a ship encounter considering the impact of the navigation environment, characterized in that: include: Step 1: Obtain the channel environment information of the ship's navigation area and the ship's own position, heading and speed information through the ship environment perception module and positioning module; Step 2: Calculate the closest encounter distance DCPA and the encounter time TCPA from the current position of the ship to the closest intersection point of the two ships based on the channel environment information in the navigable area and the ship's own position, heading and speed information; According to the channel environment information in the navigable area and the ship's own position, heading and speed information, the safe encounter distance d1, the absolutely safe encounter distance d2, the latest avoidance distance D1 and the avoidance distance D2 that can be avoided by taking measures are calculated; Step 3: Using the distance and time calculated in step 2, calculate the collision risk level SCRI in spatial position and the collision risk level TCRI between the two ships in time dimension; Step 4: Use the synthesis operator to combine the spatial risk index SCRI and the temporal risk index TCRI to calculate the spatiotemporal collision risk index STCRI; Step 5: Evaluate the risk of ship collision based on the spatial risk index SCRI, temporal risk index TCRI and spatiotemporal collision risk index STCRI.

2. The method for assessing the temporal and spatial risk of a ship encounter considering the impact of the navigation environment according to claim 1 is characterized in that: In step 2, the closest approach distance DCPA of the two ships is: Where V0 is the speed of the ship; V t for the speed of his ship; is the heading angle of own ship; is the heading angle of the other ship; θ is the azimuth of the other ship relative to our ship; r is the relative distance between the other ship and our ship.

3. The method for assessing the temporal and spatial risk of a ship encounter considering the impact of the navigation environment according to claim 2 is characterized in that: In step 2, the encounter time TCPA of the ship from its current position to the closest intersection point of the two ships is:

4. The method for assessing the temporal and spatial risk of a ship encounter considering the impact of the navigation environment according to claim 3 is characterized in that: In step 2, the safe encounter distance d1 and the absolutely safe encounter distance d2 of the two ships are: d2=K1·d1 Where W is the channel width; D is the ship width; E is the current visibility; L is the ship length; R is the distance between the two ships; V r It is the relative speed of the two ships, and K1 represents the distance expansion coefficient caused by the adverse environment.

5. The method for assessing the temporal and spatial risk of a ship encounter considering the impact of the navigation environment according to claim 4 is characterized in that: In step 2, the latest avoidance distance D1 and the avoidance distance D2 that can be avoided are: D2=K2·D1 6. The method for assessing the temporal and spatial risk of a ship encounter considering the impact of the navigation environment according to claim 5 is characterized in that: In step 3, the collision risk level SCRI in spatial position is:

7. The method for assessing the temporal and spatial risk of a ship encounter considering the impact of the navigation environment according to claim 6, characterized in that: In step 3, the collision risk level TCRI of the two ships in the time dimension is:

8. The method for assessing the temporal and spatial risk of a ship encounter considering the impact of the navigation environment according to claim 7, characterized in that: In step 4, the space-time collision risk STCRI is: In the formula, is a synthesis operator, and the specific synthesis rules are: (1) If SCRI is 0, then STCRI is 0; (2) If SCRI is not 0 and TCRI is 0, then STCRI is 0; (3) If both SCRI and TCRI are not 0, then STCRI is the larger value of SCRI and TCRI.

9. The method for assessing the temporal and spatial risk of a ship encounter considering the impact of the navigation environment according to claim 8, characterized in that: In step 5, the method for assessing the risk of ship collision is: When SCRI = 0, there is no risk of collision between the two ships; When SCRI>0 and STCRI=0, the risk of collision between the two ships will begin to occur; the give-way ship needs to take collision avoidance actions according to the International Regulations for Preventing Collisions at Sea; When STCRI>0, the risk of collision is increasing, and the give-way vessel still needs to take action to avoid collision, while the straight-line vessel is allowed to take collision avoidance action to avoid collision; When STCRI=0 or the rate of change of TCRA is greater than 0, the collision avoidance risk gradually decreases.

10. A system for assessing the temporal and spatial risk of ship encounters considering the impact of the navigation environment, characterized in that: It comprises a data acquisition module (1), a collision parameter calculation module (2), a collision risk calculation module (3), and a ship collision risk assessment module (4); The data acquisition module (1) is used to obtain the channel environment information of the ship's navigation area and the ship's own position, heading and speed information through the ship environment perception module and the positioning module; The collision parameter calculation module (2) is used to calculate the closest encounter distance DCPA of the two ships and the encounter time TCPA from the current position of the ship to the closest intersection point of the two ships according to the channel environment information in the navigable area, the ship's own position, heading and speed information; The collision parameter calculation module is also used to calculate the safe encounter distance d1, the absolute safe encounter distance d2, the latest avoidance distance D1 and the avoidance distance D2 that can be avoided based on the channel environment information in the navigable area and the ship's own position, heading and speed information; The collision risk calculation module (3) is used to calculate the collision risk level SCRI in the spatial position and the collision risk level TCRI of the two ships in the time dimension by using the distance and time calculated in step 2 and step 3; The ship collision risk assessment module (4) is used to assess the risk of ship collision based on the spatial risk SCRI, the temporal risk TCRI and the spatiotemporal collision risk STCRI.

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