A method for detecting dangerous situations of a ship in the field of inland waterway ships

Abstract

This invention discloses a method for detecting the situational danger of inland waterway vessels. The method includes the following steps: establishing an inland waterway vessel domain model; obtaining an external safety distance boundary equation through the inland waterway vessel domain model; establishing a coordinate system relative to the vessel hull and obtaining the target vessel coordinates TS; obtaining the target vessel speed through the target vessel coordinates TS, and obtaining the relative speed between the vessel and the target vessel through the target vessel speed; establishing a collision hazard detection line expression through the target vessel coordinates TS, and determining the collision intersection coordinates through the collision prediction expression and the external safety distance boundary equation; obtaining the encounter time of the intersection point of the collision hazard detection line of the target vessel and the vessel domain safety distance boundary through the collision intersection coordinates and the relative speed; classifying the situational danger level of inland waterway vessels according to the positional relationship between the collision hazard detection line and the safety distance boundary and the encounter time, which can perform real-time collision detection with high safety and good stability.

Description

Technical Field

[0001] This invention belongs to the field of ship technology, specifically relating to a method for detecting the dangerous situation of inland waterway vessels. Background Technology

[0002] The hazard assessment of the navigation situation of intelligent inland waterway vessels is an important parameter for their navigation decisions, and its results play a crucial role in ensuring the safe navigation of inland waterway vessels.

[0003] In studying the navigation situation risks of intelligent inland waterway vessels, establishing a scientific and accurate navigation situation risk assessment model is a crucial step in their navigation decision-making. However, the winding and narrow nature of inland waterways, along with bridge restrictions, introduces uncertainty and ambiguity into the assessment of navigation situation hazards for intelligent inland waterway vessels. This can lead to the inability to accurately detect the distribution of vessels around a target vessel, resulting in the lack of a unified standard for assessment calculations. Furthermore, the shielding effect of waterway connecting structures causes excessive radar scanning noise and severe signal distortion, leading to poor radar scanning performance. Currently, most vessels are equipped with onboard AIS navigation aids. Existing AIS navigation aids can only interpret AIS signals and calculate the TCPA and DCPA of two vessels encountering each other. When the encounter parameters are lower than the set threshold, an automatic alarm is triggered to remind the driver to take evasive action. Neither of these two main types of vessel navigation aids can assist the driver in assessing the navigation situation and providing timely warnings. Drivers must rely on information about the surrounding environment to determine whether a situation will occur between two vessels, which can easily lead to driver fatigue and unstable navigation. Summary of the Invention

[0004] To address the challenges posed by existing intelligent inland waterway navigation conditions, such as winding and narrow waterways and bridge limitations, which introduce uncertainty and ambiguity in assessing the navigational situation of intelligent inland waterway vessels, resulting in high costs and inaccurate detection of the distribution of surrounding vessels, and the inability of existing navigation aids to assist the operator in assessing the encounter situation and providing timely warnings, this invention aims to provide a method for detecting the hazard situation of inland waterway vessels. This method can detect the distribution of surrounding vessels, improve navigation safety, and enable real-time collision detection.

[0005] A method for detecting vessel situational hazards in the field of inland waterway vessels, the method comprising the following steps:

[0006] Step 1: Establish a model for the inland waterway vessel sector;

[0007] Step 2: Obtain the external safety distance boundary formula through the inland waterway vessel domain model;

[0008] Step 3: Establish a coordinate system relative to the ship hull and obtain the target ship coordinates TS;

[0009] Step 4: Obtain the target ship's speed using the target ship's coordinates TS, and then obtain the relative speed between your ship and the target ship using the target ship's speed;

[0010] Step 5: Establish the collision hazard detection line expression using the target vessel coordinates TS, and determine the collision intersection point coordinates using the collision hazard detection line expression and the external safety distance boundary equation;

[0011] Step 6: Obtain the encounter time of the intersection point between the collision hazard detection line of the target vessel and the safe distance boundary of the vessel's domain by using the collision intersection point coordinates and the relative velocity;

[0012] Step 7: Classify the situational danger level of inland waterway vessels based on the positional relationship between the collision hazard detection line and the safe distance boundary and the encounter time.

[0013] Furthermore, step 1 is further specified as follows:

[0014] Step 11: Obtain the initial Automatic Identification System (AIS) data of the vessel, and preprocess the initial AIS data to obtain a scatter plot of the vessel and surrounding vessels using the preprocessed AIS data.

[0015] Step 12: Obtain the density map of the ship through the scatter plot, and obtain the territory map of the ship through the density map;

[0016] Step 13: Divide the directions of surrounding ships into same-direction and opposite-direction based on the relative heading angle data, and establish a scatter distribution map of opposite-direction ships. Based on the scatter distribution map of opposite-direction ships, obtain a density distribution map of ships in the same direction and a density distribution map of ships in opposite directions.

[0017] Step 14: Establish an inland waterway vessel domain model based on the vessel's domain map.

[0018] Furthermore, step 11 specifically involves selecting a center point centered on the target vessel.

[0019] Vessels within a 1km range are used as the calculation object, and the Automatic Identification System (AIS) data of the target vessels with a speed of less than 0.5m / s are excluded;

[0020] With the target vessel as the center and its course as the longitudinal axis, a coordinate system is established relative to the target vessel in the surrounding waters. To ensure that the target vessel's heading is always aligned with the longitudinal axis of the grid at all times, the relative true directions of all other vessels in the surrounding waters are converted to the target vessel's course. In other words, the position information of all target vessels is converted to a Cartesian coordinate system with the target vessel as the origin and the heading as the y-axis, to obtain their relative bearing and relative distance. Based on the obtained relative distance and relative bearing, a scatter plot of all other target vessels is drawn.

[0021] Furthermore, step 14 specifically involves: selecting an elliptical vessel domain as the basic shape, taking the center of the target vessel as the origin, the right transverse direction as the positive x-axis, and the bow direction as the positive y-axis, establishing the vessel's coordinate system. Within this coordinate system, the boundary equations for the inland waterway vessel domain are established as follows:

[0022]

[0023] In the formula: a and b are the radii of the elliptical ship's domain in the positive and negative x-axis and y-axis directions, respectively, and x0 and y0 are the eccentric coordinates in the x-axis and y-axis directions, respectively.

[0024] Furthermore, step 2 is further specified as follows:

[0025] Step 21: Select density data at x=0 from the density distribution maps of ships traveling in the same direction and ships traveling in opposite directions, generate density curves for ships traveling in the same direction and ships traveling in opposite directions at cross-section x, determine density thresholds, and cut the density curves for ships traveling in the same direction and ships traveling in opposite directions at cross-section x to obtain and determine the coordinates of the eccentric point and the major axis radius r1 of the eccentric point in the region of ships traveling in the same direction and the coordinates of the eccentric point and the major axis radius r of the eccentric point in the region of ships traveling in opposite directions. 2；

[0026] Step 22: Select the preset density data of the center of the same-direction vessel density distribution map and the opposite-direction vessel density distribution map respectively, generate the same-direction vessel density curve and the opposite-direction vessel density curve of the y-section, determine the threshold value, cut the cross-section map according to the threshold value, and obtain the width of the same-direction vessel domain and the width of the opposite-direction vessel domain.

[0027] Step 23: Expand the inland waterway vessel domain by a factor of k along both the lower x-axis and y-axis to add an external safety distance boundary. Determine the K values ​​for the domains of vessels traveling in the same direction and those traveling in opposite directions using the external safety distance boundary equation. a and K b value;

[0028] The equation for the external safety distance boundary is as follows:

[0029]

[0030] Among them, K a The value is a coefficient of the safety distance boundary equation, referring to the expansion of the eye along the x-axis by a factor of ka in the inland waterway vessel domain, where K... b The value is a coefficient of the safety distance boundary equation, referring to the expansion k along the y-axis in the inland waterway vessel sector. b times.

[0031] Furthermore, step 3 is further specified as follows:

[0032] Establish a coordinate system relative to the ship with the ship's position as the origin and the ship's course as the positive y-axis.

[0033] With the ship's coordinates OS at time t as (0,0), and its speed... The heading is 0; the relative distance to the target vessel at time t is D, and the relative bearing is... That is, the target ship's coordinates TS are (x t ot ,y t ot ), speed relative heading Relative bearing of the target vessel and relative heading The range is set to between [-180°, 180°];

[0034]

[0035]

[0036] Target ship coordinates TS(x) t ot ,y t ot Based on the distance D between our vessel and the target vessel and their relative bearing, the calculations are as follows:

[0037]

[0038] Furthermore, step 4 is further specified as follows:

[0039] The components of the target ship's velocity along the x and y axes are as follows:

[0040] in, This represents the component of the target ship's velocity along the x-axis. This represents the component of the target ship's velocity along the y-axis.

[0041] The formulas for the relative velocity components of the ship and the target ship along the x and y axes are as follows:

[0042] in, This represents the relative velocity component of the ship's hull and the target ship along the x-axis. This represents the relative velocity component of the hull and the target vessel along the y-axis.

[0043] Furthermore, step 5 is further specified as follows:

[0044] The equation for the relative course line in the ship's coordinate system is:

[0045]

[0046] Where, k t This represents the slope of the relative course equation in the ship's coordinate system;

[0047] Combining formulas 1 and 2, we get:

[0048]

[0049] The discriminant of Formula 3 is:

[0050]

[0051] When Δ < 0, it is determined that the collision hazard detection line and the safe distance boundary do not intersect, and the target vessel is not at risk of collision.

[0052] When Δ≥0, it is determined that there is one or two intersections between the collision hazard detection line and the safety distance boundary, indicating a collision hazard.

[0053] The coordinates of the intersection point can be obtained as follows:

[0054]

[0055]

[0056] Furthermore, step 6 is further specified as follows: the meeting time of the intersection point between the collision hazard detection line of the target vessel and the safe distance boundary of the vessel's domain is:

[0057]

[0058]

[0059] Among them, T cax1 Let T be the predicted meeting time at coordinate x1. cax2 The predicted meeting time is at coordinate x2;

[0060] Then time T will be encountered ca Take T cax1 and Tcax2 Minimum value, i.e., T ca =min{T cax1 T cax2}

[0061] Furthermore, step 7 is further specified as follows:

[0062] If the target vessel is outside the vessel's territory, and if the collision hazard detection line does not intersect with the safety distance boundary, then it is considered safe.

[0063] If the target vessel is outside the vessel's territory, and if the collision hazard detection line intersects with the safety distance boundary, but T ca >T Alarm This indicates that the vessel has sufficient time to take evasive action to prevent the target vessel from entering its territorial waters, thus reducing the safety level; in this case, it is considered unsafe.

[0064] If the target vessel is outside the vessel's territory, and if the collision hazard detection line intersects with the safety distance boundary, and T ca ≤T Alarm This indicates that the vessel must take immediate evasive action to prevent the target vessel from entering its territorial waters and posing a safety risk; this situation is considered dangerous.

[0065] If the target vessel has entered the vessel's territory, it indicates that the target vessel has posed a threat to the vessel and there is a significant security risk. This situation is extremely dangerous.

[0066] Among them, T Alarm This is the collision warning time.

[0067] Compared with the prior art, the present invention has the following beneficial effects:

[0068] This invention utilizes Automatic Identification System (AIS) data to calculate and plot scatter plots and density maps with the vessel as the reference frame. It analyzes the spatial characteristics of inland waterway vessels and analyzes the spatial distribution of vessels traveling in the same or opposite directions. This allows the detection of the distribution of vessels around the target vessel, thereby improving navigation safety.

[0069] Considering the characteristics of vessel navigation in inland waterways, an elliptical vessel domain was selected as the basic shape to construct an inland vessel domain model. The parameters of the inland vessel domain model under different navigation behaviors were determined using vessel density data of same-direction and opposite-direction navigation behaviors.

[0070] A method for calculating the encounter time between the intersection of the collision hazard detection line and the safety distance boundary and the intersection of the collision hazard detection line and the safety distance boundary of the ship's domain is proposed.

[0071] A method for classifying the navigation hazard level of inland waterway vessels based on whether there is an intersection between the collision hazard detection line and the safe distance boundary and the encounter time is proposed. The collision hazard level of inland waterway vessels is divided into four levels: safe, slightly unsafe, dangerous, and very dangerous. The method is effective, stable, and real-time. Attached Figure Description

[0072] Figure 1 This is a scatter plot of the target ships in an embodiment of the present invention;

[0073] Figure 2 This is a ship density map (with scatter plots) in an embodiment of the present invention;

[0074] Figure 3 This is a ship distribution density map in an embodiment of the present invention;

[0075] Figure 4 This is a schematic diagram of the target ship domain in an embodiment of the present invention;

[0076] Figure 5 This is a diagram showing the relative headings of surrounding vessels in an embodiment of the present invention.

[0077] Figure 6 This is a scatter plot of ships sailing in the same direction in an embodiment of the present invention;

[0078] Figure 7 This is a density distribution diagram (with scatter points) of ships sailing in the same direction in an embodiment of the present invention;

[0079] Figure 8 This is a density distribution diagram of ships sailing in the same direction in an embodiment of the present invention;

[0080] Figure 9 This is a scatter plot of opposing ships in an embodiment of the present invention;

[0081] Figure 10 This is a density distribution diagram of opposing ships (with scatter plots) in an embodiment of the present invention;

[0082] Figure 11 This is a density distribution diagram of opposing ships in an embodiment of the present invention;

[0083] Figure 12 This is a schematic diagram of an eccentric elliptical inland waterway vessel domain model in an embodiment of the present invention;

[0084] Figure 13 This is the density curve of ships sailing in the same direction at section x in this embodiment of the invention;

[0085] Figure 14 This is the density curve of facing ships at section x in an embodiment of the present invention;

[0086] Figure 15This is the density curve of ships sailing in the same direction at section y in an embodiment of the present invention;

[0087] Figure 16 This is the density curve of facing ships at section y in an embodiment of the present invention;

[0088] Figure 17 This is a safety zone diagram for vessels traveling in the same direction, as shown in this embodiment of the invention.

[0089] Figure 18 This is a safety zone diagram of opposing vessels in an embodiment of the present invention;

[0090] Figure 19 This is a schematic diagram of collision hazard assessment in an embodiment of the present invention;

[0091] Figure 20 This is a diagram showing the tracks of the vessel and the target vessel in an embodiment of the present invention.

[0092] Figure 21 This is a diagram showing the target vessel's track relative to its own vessel in an embodiment of the present invention;

[0093] Figure 22 T obtained through Automatic Identification System (AIS) data of ships ca Change diagram;

[0094] Figure 23 T is calculated using this invention. ca Change diagram. Detailed Implementation

[0095] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0096] In one embodiment of the present invention, a method for detecting vessel situational hazards in the field of inland waterway vessels includes the following steps:

[0097] Step 1: Establish a model for the inland waterway vessel sector;

[0098] Step 2: Obtain the external safety distance boundary formula through the inland waterway vessel domain model;

[0099] Step 3: Establish a coordinate system relative to the ship hull and obtain the target ship coordinates TS;

[0100] Step 4: Obtain the target ship's speed using the target ship's coordinates TS, and then obtain the relative speed between your ship and the target ship using the target ship's speed;

[0101] Step 5: Establish a collision hazard detection line expression using the target vessel coordinates TS, and determine the collision intersection coordinates using the collision prediction expression and the external safety distance boundary equation;

[0102] Step 6: Obtain the encounter time of the intersection point between the collision hazard detection line of the target vessel and the safe distance boundary of the vessel's domain by using the collision intersection point coordinates and the relative velocity;

[0103] Step 7: Classify the situational danger level of inland waterway vessels based on the positional relationship between the collision hazard detection line and the safe distance boundary and the encounter time.

[0104] The present invention will be further described below with reference to a specific embodiment:

[0105] A method for detecting the safety range of vessels in the field of inland waterway vessels, the method is as follows:

[0106] Because the initial Automatic Identification System (AIS) data contains some anomalies, it is necessary to remove data with abnormal vessel positions from the selected AIS data, i.e., data indicating vessels are not within the navigation area, have speed but maintain their position, exhibit abnormal speed, or have abnormal heading. Furthermore, since this invention only considers the vessel's current navigation state, it is necessary to determine the vessel's current navigation state based on its speed and remove AIS data with a speed less than 0.5 m / s. Simultaneously, considering the size characteristics of inland waterway vessels, vessels within a 1 km radius of the vessel are selected as the calculation objects. The processed AIS data is then used to perform the following density map calculations.

[0107] Using the ship as the center and its course as the longitudinal axis, a coordinate system is established relative to the ship in the surrounding waters. First, at any given moment, the relative distance and true bearing of the target ship can be calculated using the latitude and longitude of the ship and all other ships in the surrounding waters. Second, to ensure that the target ship's heading is always aligned with the longitudinal axis of the grid at all navigation moments, the problem of the constantly changing relative bearings of other ships due to the ship's navigation state must be addressed. This requires converting the true relative bearings of all other ships in the surrounding waters with the ship's course to obtain the relative bearing, ensuring the accuracy of the selected statistical sample. Finally, a scatter plot of all other target ships is drawn based on the calculated relative distances and bearings, as shown below. Figure 1 As shown.

[0108] By observing the scatter distribution map of the target ships, there is indeed a sparse area of ​​ships near the origin, which is the ship's domain space.

[0109] To more accurately describe the distribution of the waters surrounding this vessel relative to other target vessels, it is necessary to convert the scatter plot of vessel distribution into a density plot. The density plot includes a vessel density plot (such as...). Figure 2 ) and ship distribution density map (such as Figure 3The analysis was performed. During the transformation process, a unit distance of 5m was selected, and the number of ship points within a unit distance of each coordinate point was counted and divided by the area to obtain the density value of that coordinate.

[0110] The density of each coordinate point of the vessel is statistically analyzed, and different colors are used to fill in the density values ​​to obtain a density map of the vessel. By observing and analyzing this density map and density data, the shape and size of the vessel's domain can be determined. Figure 4 As shown in the diagram, the center of the density map represents a small area of ​​water surrounding the vessel, whose density is significantly lower than that of other surrounding waters. This area can be considered the vessel's territory.

[0111] The vessel's domain is asymmetrically elliptical, with the major axis of the ellipse parallel to the bow. The center of the ellipse in the domain is eccentric to the center of the vessel, i.e., the origin of the coordinate system. The center of the ellipse in the domain is located to the left and rear of the center of the vessel.

[0112] The characteristics of ship navigation in separate lanes allow us to analyze surrounding vessels by categorizing them into two groups: those traveling in the same direction and those traveling in opposite directions. First, we analyze the distribution of surrounding vessels relative to their course, using the ship's own course as a reference. Figure 5 As shown.

[0113] Depend on Figure 5 It can be seen that 77.5% of the ships have relative headings between -180° and -160°, -20° and 20°, and 160° and 180°. Therefore, data with relative headings between -20° and 20° are selected as the same-direction data, and data with relative headings between -180° and -160° and 60° and 180° are selected as opposite-direction data, and density statistical analysis is performed on them respectively.

[0114] First, data with a relative heading between -20 degrees and 20 degrees are selected as same-direction data, and a scatter plot of same-direction ships is drawn, such as... Figure 6 As shown.

[0115] Based on the characteristic that the separation of upstream and downstream navigation channels on inland waterways changes from side to side depending on the channel flow conditions, the scatter plot is symmetrically supplemented along x=0 to obtain a distribution map of vessel density in the same direction, as shown below. Figure 7 and Figure 8 As shown.

[0116] Secondly, data with relative headings between -180 and -160 degrees and between 60 and 180 degrees were selected as the data for opposing navigation, and a scatter plot of opposing navigation vessels was drawn, such as... Figure 9 As shown.

[0117] Considering that the separation of upstream and downstream navigation lanes on inland waterways can change depending on the channel flow conditions, the scatter plot is symmetrically supplemented along x=0 to obtain a distribution map of opposing vessel density, as shown below. Figure 10 and Figure 11 As shown.

[0118] In summary, when sailing in the same direction, vessels primarily engage in following or overtaking maneuvers, resulting in a shorter forward and longer rearward berth. This means the center of the berth shifts aft, and the space on either side is relatively narrow due to the width of the lane dividers. Conversely, when sailing in opposite directions, vessels primarily engage in head-on encounters, resulting in a longer forward and shorter rearward berth. This means the center of the berth shifts forward, and the space on either side is generally wider than that of vessels sailing in the same direction due to the width of the lane dividers.

[0119] Currently, ship domain models are mainly constructed through statistical analysis, analytical representation, AIS data, and intelligent technologies. However, regardless of the method used, ship domain models all have certain limitations. This is because there are many factors to consider when constructing a ship domain model, and it is extremely difficult to incorporate all of them into the model.

[0120] Considering the characteristics of ship navigation in inland waterways, an elliptical ship domain is selected as the basic graphic, such as... Figure 12 As shown.

[0121] Establish a coordinate system for the ship with its center as the origin, the positive x-axis as the right transverse direction, and the positive y-axis as the bow direction. Under this coordinate system, the boundary equations for the inland waterway vessel domain are given in equation (Formula 1).

[0122]

[0123] In the formula: a and b are the radii of the elliptical ship's domain in the positive and negative x-axis and y-axis directions, respectively, and x0 and y0 are the eccentric coordinates in the x-axis and y-axis directions, respectively.

[0124] First, select the density data at x=0, the center of the same-direction and opposite-direction vessel navigation density map, and generate the same-direction vessel density curve and the opposite-direction vessel density curve at section x, as follows: Figure 13 and Figure 14 As shown.

[0125] Different threshold values ​​were used to observe changes in the ship's domain, thus determining the appropriate threshold value. A 40% threshold cut was ultimately chosen, determining the coordinates of the eccentric point in the same-direction ship's domain as (0, -140), and the major axis radius b1 as 360 meters. The major axis radius is obtained from the coordinate range; for example, the major axis radius b1 corresponds to the horizontal coordinate of the ship's domain between -500 and 220 meters, so the major axis radius b1 is 720 / 2 = 360 meters. A 15% threshold cut was chosen, with the coordinates of the eccentric point in the opposing ship's domain as (0, 160), and the horizontal coordinate range of the ship's domain being (-190 to 510), thus the major axis radius b2 is 350 meters.

[0126] Secondly, density data at the center of the same-direction and opposite-direction vessel density distribution maps at y=-140 and y=160, respectively, and several rows of grid density data along the minor axis direction were selected to generate the density curves of same-direction vessels at the y-section and the density curves of opposite-direction vessels at the y-section, as follows: Figure 15 and Figure 16 As shown.

[0127] Finally, different threshold values ​​were used to observe changes in the ship domain to determine appropriate threshold values. When the cross-sectional view was cut with 40% of the maximum density as the threshold, the width 'a' of the domain for ships traveling in the same direction was determined to be 30 meters, and the width 'a' of the domain for ships traveling in opposite directions was determined to be 70 meters.

[0128] Considering that relying solely on the vessel's own perimeter to determine the existence of a collision hazard could lead to a tense situation in complex inland waterway encounter scenarios, preventing the two vessels from passing at a safe distance, the inland waterway vessel perimeter is expanded by a factor of k along both the lower x-axis and y-axis to add an external safety distance boundary, thereby improving the safety of vessels during collision avoidance. The boundary equations are as follows:

[0129]

[0130] In the formula: k a k b Generally, the value of k is taken between [1, 2]. Through observation and comparison, the k value is finally determined when ships are sailing in the same direction. a =1.5, k b =1; k = 1; when facing the navigation of ships a =1.15, k b =1.28. The final safety zone for ships includes the safety area for ships traveling in the same direction and the safety area for ships traveling in opposite directions, such as... Figure 17 and Figure 18 As shown.

[0131] Considering the characteristics of vessel navigation in inland waterways, an elliptical vessel domain is chosen as the basic shape. The eye of the inland vessel domain is expanded by a factor of k along the lower x-axis and y-axis to add an external safety distance boundary, thereby improving the safety of vessels during collision avoidance. The equation for the safety distance boundary of the inland vessel domain is as follows:

[0132]

[0133] In the formula: a and b are the radii of the elliptical ship's domain in the positive and negative x-axis and y-axis directions, respectively, and x0 and y0 are the eccentric coordinates in the x-axis and y-axis directions, respectively.

[0134] Combined with the collision avoidance characteristics of inland river ships, when sailing in the same direction, the risk judgment starts when the ship is 1 km away from the target ship. When sailing in the opposite direction, the risk judgment starts when the ship is 1.5 km away from the target ship. The method for judging whether there is a collision risk between the ship and the target ship is as follows: Taking the ship as the center, construct a collision risk detection circle with a radius of R. When the target ship enters the collision risk detection circle of the ship, that is, D < R, according to the position coordinates and relative course of the target ship, a collision risk detection line is formed. First, judge whether the target ship is a ship sailing in the same direction or in the opposite direction, and then judge whether there is a collision risk between the two ships by whether the collision risk detection line crosses the corresponding safety range of the ship domain in the same direction or in the opposite direction. See Figure 19 .

[0135] In order to judge the collision risk in the above way, it is necessary to obtain the straight-line equation of the collision risk detection line in the ship's coordinate system, and联立求解 the collision risk detection line equation and the ship domain safety distance boundary equation to find the intersection point. If there is an intersection point, it indicates that there is a collision risk.

[0136] Specifically as follows:

[0137] Establish a coordinate system relative to the ship with the ship's position as the coordinate origin and the ship's course as the positive direction of the y-axis;

[0138] Taking the coordinate OS of the ship at time t as (0,0), the ship speed The course is 0; the relative distance of the target ship at time t is D, and the relative bearing is That is, the target ship coordinates TS are (x t ot ,y t ot ), the ship speed The relative course The relative bearing of the target ship And the relative course the ranges are all set between [-180°, 180°]; [[ID=3 ]]

[0139]

[0140]

[0141] The target ship coordinates TS(x t ot ,y t ot ), calculated according to the distance D and relative bearing between the ship and the target ship, as follows:

[0142]

[0143] The components of the target ship speed on the x and y axes are as follows:

[0144] It should be noted that the expression "联立求解" in the original text is not a standard English term. It might be a specific jargon in the relevant field. Here, I translated it as "联立求解" as accurately as possible according to the context. If there is a more appropriate English expression for this term in the field of patent translation, it may need to be adjusted accordingly. in, This represents the component of the target ship's velocity along the x-axis. This represents the component of the target ship's velocity along the y-axis.

[0145] The formulas for the relative velocity components of the ship and the target ship along the x and y axes are as follows: in, This represents the relative velocity component of the ship's hull and the target ship along the x-axis. This represents the relative velocity component of the hull and the target vessel along the y-axis.

[0146] when When the slope k of the straight line is:

[0147]

[0148] when When the slope k of the straight line is:

[0149] k t =0;

[0150] Based on the point-slope form of the equation of a straight line, the equation of the relative course line in the ship's coordinate system can be obtained as follows:

[0151] By combining the two equations, the intersection point of the collision hazard detection line and the safety distance boundary of the ship's domain can be obtained.

[0152] Because the equations for the collision hazard detection line and the safety distance boundary of the inland waterway vessel area are complex to analyze, a quadratic equation discriminant is used to determine the number of intersections between the collision hazard detection line and the two boundaries.

[0153] The equation for the safety distance boundary in the inland waterway vessel sector is:

[0154] Combining formulas 1 and 2, we get:

[0155]

[0156]

[0157] Its discriminant is:

[0158]

[0159] When Δ < 0, it is determined that there is no intersection between the collision hazard detection line and the safety distance boundary, and there is no collision hazard for this vessel.

[0160] When Δ≥0, it is determined that there is one or two intersection points between the collision hazard detection line and the safety distance boundary, indicating a collision hazard; and the x-coordinate of the intersection point is:

[0161]

[0162]

[0163] The time of encounter between the collision hazard detection line of the target vessel and the boundary of the safe distance in the shipping area is:

[0164]

[0165]

[0166] Meeting time to take T cax1 T cax2 Small value:

[0167] T ca =min{T cax1 T cax2}

[0168] To clearly indicate the state of danger, it is also necessary to classify the current level of ship collision danger. This invention classifies the collision danger level of Channel 1 according to the following criteria: the collision danger detection line does not intersect with the safety distance boundary; the collision danger detection line intersects with the safety distance boundary but does not intersect with the boundary of the ship's territory; and the collision danger detection line does not intersect with the boundary of the ship's territory. This invention classifies the collision danger level of inland waterway vessels into four levels: safe, slightly unsafe, dangerous, and very dangerous.

[0169] If the target vessel is outside the vessel's territory, and if the collision hazard detection line does not intersect with the safety distance boundary, then it is considered safe.

[0170] If the target vessel is outside the vessel's territory, and if the collision hazard detection line intersects with the safety distance boundary, but T ca >T Alarm This indicates that the vessel has sufficient time to take evasive action to prevent the target vessel from entering its territorial waters, thus reducing the safety level; in this case, it is considered unsafe.

[0171] If the target vessel is outside the vessel's territory, and if the collision hazard detection line intersects with the safety distance boundary, and T ca ≤T Alarm This indicates that the vessel must take immediate evasive action to prevent the target vessel from entering its territorial waters and posing a safety risk; this situation is considered dangerous.

[0172] If the target vessel has entered the vessel's territory, it indicates that the target vessel has posed a threat to the vessel and there is a significant security risk. This situation is extremely dangerous.

[0173] Among them, the collision alarm time T Alarm Set to 60 seconds.

[0174] In one embodiment of the invention, the vessel travels upstream on a channel with a width of approximately 350 meters, an upstream lane of approximately 150 meters, a downstream lane of approximately 200 meters, and a channel maintenance depth of 8 meters. Facing downstream, the downstream lane is on the left side of the entire channel, and the upstream lane is on the right side of the entire channel.

[0175] During this voyage, the vessel overtook the target vessel. First, the target vessel advanced upstream at a speed of 3-4 knots, while the vessel followed at 13 knots. Second, as the distance gradually closed to approximately 500 meters, the vessel turned to starboard to begin overtaking. Third, the vessel and target vessel entered a parallel navigation phase, maintaining a distance of approximately 50 meters. Finally, the vessel overtook the target vessel to starboard, turned to port, and returned to the middle of the upstream channel. This completed the overtaking maneuver. The navigation trajectory is as follows: Figure 20 As shown, the target vessel's track relative to this vessel is as follows: Figure 21 As shown, the entire voyage process, as Figure 22 The figure shows the time-varying curve of Tca calculated using AIS target vessel data, as shown below. Figure 23 The figure shows the meeting time T calculated using this invention. ca Curve showing how it changes over time.

[0176] contrast Figure 22 and Figure 23 visible:

[0177] First, by determining the intersection of the collision hazard detection line and the safety distance boundary at different times and calculating the encounter time Tca of the intersection of the target vessel's collision hazard detection line and the vessel's safety distance boundary, the navigation risk level of the target vessel relative to the vessel can be effectively described.

[0178] Secondly, because the target vessel's AIS data transmission frequency is low and the AIS data has low real-time performance, using only AIS data to determine the risk level of the target vessel results in missed alarms. Compared with the present invention, the alarm stability for determining the risk level of the target vessel is poor.

[0179] Finally, due to the low real-time performance of AIS data, the response time of using AIS data alone to determine the risk level of a target vessel is slower than that of using the method of this invention. The lag time is approximately 5 to 10 seconds, which may affect the driver's misjudgment of navigation risks.

[0180] In summary, the present invention uses the method of determining the navigation risk level of a target vessel by determining whether there is an intersection between the collision hazard detection line and the safety distance boundary and by calculating the encounter time parameter of the intersection between the collision hazard detection line of the target vessel and the safety distance boundary of the vessel's domain. This method can accurately reflect the navigation risk of the target vessel relative to the vessel itself, and the warning data is stable and has good real-time performance, which can effectively assist the driver in identifying navigation risks.

[0181] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for detecting a dangerous situation of a vessel in the field of inland vessels, characterized in that, The method includes the following steps: Step 1: Establish a model for the inland waterway vessel sector; Step 2: Obtain the external safety distance boundary equation using the inland waterway vessel domain model; Step 3: Establish a coordinate system relative to the ship's hull and obtain the target ship's coordinates TS. The target ship's coordinates TS are represented as (x... t ot ,y t ot ); Step 4: Obtain the target ship's speed from the target ship's coordinates TS, and then obtain the relative speed between your ship and the target ship from the target ship's speed; Step 5: Establish the collision hazard detection line expression using the target vessel coordinates TS, and determine the collision intersection point coordinates using the equations of the collision hazard detection line and the external safety distance boundary. Step 6: Obtain the encounter time of the intersection point between the collision hazard detection line of the target vessel and the safe distance boundary of the vessel's domain by using the collision intersection point coordinates and the relative velocity; Step 7: Classify the situational danger level of inland waterway vessels based on the positional relationship between the collision hazard detection line and the safe distance boundary and the encounter time; Step 1 specifically involves: Step 11: Obtain the initial Automatic Identification System (AIS) data of the vessel, and preprocess the initial AIS data to obtain a scatter plot of the vessel and surrounding vessels using the preprocessed AIS data. Step 12: Obtain the density map of the ship through the scatter plot, and obtain the territory map of the ship through the density map; Step 13: Divide the directions of surrounding ships into same-direction and opposite-direction using the angle data of relative headings, and establish a scatter distribution map of ships sailing in the same direction and a scatter distribution map of ships sailing in opposite directions. Based on the scatter distribution map of ships sailing in the same direction and the scatter distribution map of ships sailing in opposite directions, obtain a density distribution map of ships sailing in the same direction and a density distribution map of ships sailing in opposite directions. Step 14: Establish an inland waterway vessel domain model based on the vessel's domain map; Step 14 specifically involves: selecting an elliptical vessel domain as the basic shape, taking the center of the target vessel as the origin, the right transverse direction as the positive x-axis, and the bow direction as the positive y-axis, to establish the vessel's coordinate system. Within this coordinate system, the boundary equations for the inland waterway vessel domain are established as follows: ； In the formula: a and b are the radii of the elliptical ship in the positive and negative x-axis and y-axis directions, respectively, and x0 and y0 are the eccentric coordinates in the x-axis and y-axis directions, respectively; Step 2 is as follows: Step 21: Select the density data at x=0 in the same-direction vessel density distribution map and the opposite-direction vessel density distribution map, generate the same-direction vessel density curve and the opposite-direction vessel density curve at the x-section, determine the density threshold, cut the same-direction vessel density curve and the opposite-direction vessel density curve at the x-section, and obtain the coordinates of the eccentric point and the major axis radius r1 of the same-direction vessel domain and the coordinates of the eccentric point and the major axis radius r2 of the opposite-direction vessel domain; Step 22: Select the preset density data of the center of the same-direction vessel density distribution map and the opposite-direction vessel density distribution map respectively, generate the same-direction vessel density curve and the opposite-direction vessel density curve of the y-section, determine the threshold value, cut the cross-section map according to the threshold value, and obtain the width of the same-direction vessel domain and the width of the opposite-direction vessel domain. Step 23: Expand the inland waterway vessel domain by a factor of k along both the x-axis and y-axis to add an external safety distance boundary. Determine the K values ​​for the domains of vessels traveling in the same direction and those traveling in opposite directions using the external safety distance boundary equation. a and K b value; The equation for the external safety distance boundary is as follows: (Formula 1); Among them, K a The value is a coefficient of the safety distance boundary equation, indicating the expansion of k along the x-axis in the inland waterway vessel domain. a times, K b The value is a coefficient of the safety distance boundary equation, referring to the expansion of k along the y-axis in the inland waterway vessel domain. b times; Step 5 specifically involves: The equation for the relative course in the ship's coordinate system is: (Formula 2); Where, k t This represents the slope of the relative course equation in the ship's coordinate system; Combining formulas 1 and 2, we get: (Formula 3); The discriminant of Formula 3 is: ； When a collision danger detection line and a safety distance boundary do not exist intersection points, the target ship does not exist collision danger; When one or two intersection points exist between the collision danger detection line and the safety distance boundary, a collision danger exists. The coordinates of the intersection point can be obtained as follows: ； ； Step 6 specifically refers to the meeting time of the intersection of the collision hazard detection line of the target vessel and the boundary of the safe distance of the vessel's domain: ； ； Among them, T cax1 Let T be the predicted meeting time at coordinate x1. cax2 The predicted meeting time is at coordinate x2; This represents the relative velocity component of the ship's hull and the target ship along the x-axis. Then time T will be encountered ca Take T cax1 and T cax2 Minimum value, i.e. ; Step 7 specifically includes: If the target vessel is outside the vessel's territory and the collision hazard detection line does not intersect with the safety distance boundary, then it is considered safe. If the target vessel is outside the vessel's territory, and the collision hazard detection line intersects with the safety distance boundary, but T ca >T Alarm This indicates that the vessel has sufficient time to take evasive action to prevent the target vessel from entering its territorial waters, thus reducing the safety level; in this case, it is considered unsafe. If the target vessel is outside the vessel's territory, and the collision hazard detection line intersects with the safety distance boundary, and T ca ≤T Alarm This indicates that the vessel must take immediate evasive action to prevent the target vessel from entering its territorial waters and posing a safety risk; this situation is considered dangerous. If the target vessel has entered the vessel's territory, it indicates that the target vessel has posed a threat to the vessel and there is a significant security risk. This situation is extremely dangerous. where T Alarm is the time to collision warning.

2. The method according to claim 1, wherein, Step 11 specifically involves: selecting ships within a 1km radius of the ship as the calculation object, and removing AIS data information with a speed of less than 0.5m / s from the ship's data. With the target vessel as the center and its course as the longitudinal axis, a coordinate system is established relative to the target vessel in the surrounding waters. To ensure that the target vessel's heading is always aligned with the longitudinal axis of the grid at all times, the relative true directions of all other vessels in the surrounding waters are converted to the target vessel's course. In other words, the position information of all target vessels is converted to a Cartesian coordinate system with the target vessel as the origin and the heading as the y-axis, to obtain their relative bearing and relative distance. Based on the obtained relative distance and relative bearing, a scatter plot of all other target vessels is drawn.

3. The method according to claim 2, wherein, Step 3 specifically involves: Establish a coordinate system relative to the ship with the ship's position as the origin and the ship's course as the positive y-axis. With the ship's coordinates OS at time t as (0,0), and its speed... The heading is 0; the relative distance of the target ship at time t is D, and the relative bearing is... That is, the target ship coordinates TS are (x t ot ,y t ot ), speed relative heading The relative bearing of the target vessel and relative heading The range is set to between [-180°, 180°]; ； ； Target ship coordinates TS (x t ot ,y t ot Based on the distance D between our vessel and the target vessel and their relative bearing, the calculations are as follows: 。 4. The method according to claim 3, wherein, Step 4 is as follows: The components of the target ship's velocity along the x and y axes are as follows: ; wherein denotes the component of the target ship velocity in the x-axis direction, denotes the component of the target ship velocity in the y-axis direction; The formulas for the magnitudes of the x and y components of the relative velocity between the ship and the target ship are as follows: ;in, This represents the relative velocity component of the ship's hull and the target ship along the x-axis. This represents the relative velocity component of the hull and the target vessel along the y-axis.

Images