Ship Early Warning Method Based on Expanded Ellipse and Expanded Circle Models

Abstract

The present invention discloses a ship warning method based on an expanded ellipse and an expanded circle model, which relates to the technical field of warning and monitoring. The warning method includes the following steps: establishing an expanded ellipse model of two ships; calculating parameters such as the domain distance, safety distance, straight-line distance, the angle between the tangent of the circle with the safety distance as the radius and the relative position connection line, and the angle between the relative velocity vector and the relative position connection line; comparing each parameter with the collision detection distance, TCPA, and DCPA to achieve blue warning, orange warning, and red warning. The present invention constructs an expanded ellipse model for two ships, and by calculating various parameters between the two expanded ellipses, it can more comprehensively predict the relative position and dynamic relationship between the two ships, and is used to give different levels of warnings for different degrees of collision risks, improving the safety of navigation.

Description

Technical Field

[0001] The present invention relates to the technical field of early warning monitoring, and particularly to a ship early warning method based on an expanded ellipse and an expanded circle model. Background Art

[0002] The water depth is limited, and the shallow water effect is obvious, affecting the ship's maneuverability. Affected by tides, the ship density is large during peak periods, forming a ship concentration area in a local time and area, and advancing as a whole with the tide, increasing the difficulty of ship maneuvering and collision. The types of navigable ships are complex, especially small ships, with low crew quality and poor ship performance. The crew's ship handling skills and awareness of following rules are poor, and their maneuvers are random, making it easy to have collision risks. When a ship is working, the driver needs to monitor whether there are other ships around by himself. If so, he needs to further judge whether he needs to operate his own ship to avoid.

[0003] Chinese patent document CN109697892A discloses a spatio-temporal perception-based intelligent early warning method for ship collision risks. It judges which ships in the ship object set A around the target ship for collision early warning are directly included in the area of the target ship for collision detection according to the area of the target ship and the positions of other ships, and outputs the set of ships that may collide with the target ship; the risk level of possible ship collisions. However, this document only warns of collisions based on the distance between two ships, ignoring other actual factors, resulting in low early warning accuracy, and does not comprehensively consider various factors to give different levels of early warning for whether a collision occurs. Summary of the Invention

[0004] Aiming at the problems of few factors used for early warning in current ship early warning and not comprehensively considering various factors to give different levels of early warning for whether a collision occurs, resulting in low early warning accuracy, the present invention provides a ship early warning method based on an expanded ellipse and an expanded circle model.

[0005] To solve the above technical problems, the present invention adopts the following technical solutions: The ship early warning method based on an expanded ellipse and an expanded circle model includes the following steps: S1 Obtain the longitude, latitude, speed, and course information of my ship and other ships, establish a rectangular coordinate system, and establish an expanded ellipse model of my ship and other ships; S2 Calculate the domain distance between the expanded ellipses of my ship and other ships, the safe distance d between my ship and other ships m , the distance between my ship and other ships, the angle θ between the tangent of the circle with the safe distance d m as the radius and the connecting line of the relative positions m and the angle θ between the relative velocity vector and the relative position vector; S3 Judge whether the distance between my ship and other ships satisfies being less than the collision detection distance CD. If it satisfies, enter S4; S4 Judge whether the distance between my ship and other ships is within the safe distance dm If the collision detection distance CD is satisfied, enter S5, if not, enter S6; S5 determines whether the angle between the speed vector of our ship and the speed vector of the other ship is less than the angle θ between the relative speed vector and the relative position vector, if so, a blue warning is issued; S6 calculates TCPA and DCPA, and determines 0<=TCPA<=TA and DCPA<=DA. If any condition is satisfied, an orange warning is issued; if both conditions are satisfied, a red warning is issued; if both conditions are not satisfied, enter S1.

[0006] Furthermore, in S2, the range distance R of our ship is calculated os The distance R between the ship and the area ts :

[0007] Convert the longitude and latitude coordinates of our ship and the other ship into northeast coordinates, find the equation of the line connecting our ship and the other ship, and use the equation of the line to combine with the ellipse equation of our ship and the ellipse equation of the other ship, and find the two intersection points of the equation of the line and the ellipse equation of our ship: Point 1 (x 1 ,y 1 ), point 2(x 2 ,y 2 ), find the two intersection points of the connecting line equation and the other ship's ellipse equation: point 3(x 3 ,y 3 ), point 4(x 4 ,y 4 );

[0008] Use the Pythagorean theorem to find the point 1(x 1 ,y 1 ) and point 2(x 2 ,y 2 ), point 3(x 3 ,y 3 ) and point 4(x 4 ,y 4 ) between the two sides;

[0009] Let the coordinates of my ship be O(x os ,y os ), the coordinates of the other ship are T(x ts ,y ts ), the line equation of the two ship positions OT equation:

[0010] y = k*x + d;

[0011] Joint:

[0012]

[0013] In the formula, θ 1 is the heading angle of our ship; θ 2 is the heading angle of the other ship; the slope of the straight line is The straight-line intercept is

[0014] Solve the equation to find the coordinates of point 1 (x 1 , y 1 ), point 2 (x 2 , y 2 ), point 3 (x 3 , y 3 ), and point 4 (x 4 , y 4 );

[0015]

[0016] Furthermore, in S2, calculate the safety distance d between my ship and the other ship m :

[0017] d m = R os + d safe + R ts ;

[0018] In the formula, d safe is a distance determined by comprehensively considering the maneuvering performance, respective speeds, relative speed, and water area type conditions of my ship and the other ship;

[0019] d safe The calculation formula for is:

[0020]

[0021] In the formula, timestep is the time step, with the unit of h; |vr| is the absolute value of the relative speed when my ship and the other ship are approaching each other, and 0 when they are moving away from each other, with the unit of knot; T 90 is the time taken for the ship to complete a 90° change in the full-speed turning course angle, with the unit of s; A d is the longitudinal distance traveled by the center of gravity when the ship completes a 90° change in the full-speed turning course angle, generally taking 2.8 - 4 times the ship length, with the unit of m; d nature is the safety distance required under natural conditions, generally taking 0.5 nautical miles, and can also be set according to experience; d water is the safety distance required for the water area where the ship is located, generally taking 0.5 nautical miles, and can also be set according to experience; μ n is the coefficient of d nature , with a minimum value of 0 and a maximum value of 1; μ w is the coefficient of d water , with a minimum value of 0 and a maximum value of 1.

[0022] Furthermore, among them, the calculation process of T 90 is obtained through the following method:

[0023] R = k 90 *L;

[0024] wherein, R is the turning radius; k 90 takes values from 3 to 7, general merchant ships take values from 4 to 5, and large ships take values from 5 to 7; L is the ship length;

[0025] The turning radius is calculated using the angular velocity:

[0026]

[0027] wherein, V is the ship speed; ω is the angular velocity;

[0028] The time taken to rotate by an angle of Δθ is:

[0029]

[0030] After arrangement, we get:

[0031]

[0032] Therefore:

[0033]

[0034] Furthermore, in S2, calculate the angle θ m between the tangent of the circle with a radius of the safe distance d m and the connecting line of the relative positions, as well as the angle θ between the relative velocity vector and the relative position vector:

[0035] In triangle OTS, θ m is equal to the arctangent function of d m and OS, and the magnitude of OS can be obtained through the Pythagorean theorem;

[0036] The magnitude of θ is obtained using the arccosine function of the dot product of the relative position vector OT and the relative position vector v ot point;

[0037] Therefore:

[0038]

[0039] wherein, is the straight-line distance between our ship O and the other ship T; is the position vector pointing from our ship O to the other ship T;

[0040]

[0041] wherein, is the relative velocity vector of our ship O with respect to the other ship T; is the dot product of the relative position vector and the relative velocity vector.

[0042] Further, in S3, calculate the collision detection distance CD:

[0043] CD = d m + ρ 0 ;

[0044] ρ 0 = max(fk * R ts , ρ 0m i n );

[0045] Set ρ 0 Two factors need to be considered: (1) Overtaking situation: ρ 0min = 0.5 nautical miles; Crossing and head-on situations: ρ 0min = 1 nautical mile; (2) fk: Set by oneself, R ts : The domain distance of the other ship.

[0046] Further, in S6, calculate DCPA, and DCPA is obtained through the sine function in triangle OTP:

[0047]

[0048] Calculate TCPA, and the magnitude of TCPA is equal to the distance of PT divided by the magnitude of the speed in the direction of PT. PT is obtained by using the cosine of the modulus of the relative position vector in triangle OTP:

[0049]

[0050] In the formula, is the magnitude of the relative speed, which is equal to the magnitude of .

[0051] Further, in S5, if the condition is satisfied, then a blue warning is issued;

[0052] where distance is the distance between my ship and the other ship.

[0053] Further, in S6, if any of the conditions or is satisfied, then an orange warning is issued;

[0054] where DA is the semi-major axis of the ellipse equation of the other ship set; TA is the DCPA threshold set according to the empirical value.

[0055] Further, in S6, if both and are satisfied, then a red warning is issued.

[0056] The beneficial effects of the present invention are as follows: The present invention constructs an expanded elliptical model for two ships. By calculating parameters such as the domain distance, safety distance, straight-line distance, and included angle between the two expanded ellipses, it can more comprehensively predict and evaluate the relative position and dynamic relationship between the two ships, and is used to issue early warnings of different levels for different degrees of collision risks. It can help the operator more accurately judge the potential collision risk between the two ships and take collision avoidance measures in a timely manner to ensure navigation safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 The schematic diagram of the principle of an embodiment of the present invention is shown.

[0058] Figure 2 The flowchart of the present invention is shown.

[0059] Figure 3 The schematic diagram of the construction of the expanded elliptical model is shown.

[0060] Figure 4 The schematic diagram of calculating the domain distance between two ships is shown.

[0061] Figure 5 The schematic diagram of calculating the safety distance between two ships is shown.

[0062] Figure 6 The schematic diagram of calculating the included angle between the relative velocity vector and the connecting line of the relative position and the included angle between the tangent of the circle with the safety distance as the radius and the connecting line of the relative position is shown.

[0063] Figure 7 The schematic diagram of calculating TCPA and DCPA is shown. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0064] The present invention discloses a ship warning method based on an expanded ellipse and an expanded circle model. The following describes a specific embodiment of the present invention in conjunction with the accompanying drawings.

[0065] The ship warning method based on the expanded ellipse and the expanded circle model includes the following steps: S1 Obtain the longitude, latitude, speed, and heading information of our ship and the other ship, establish a rectangular coordinate system, and establish an expanded ellipse model of our ship and the other ship; S2 Calculate the domain distance between the expanded ellipses of our ship and the other ship, the safety distance d between our ship and the other ship m , the distance between our ship and the other ship, the included angle θ between the tangent of the circle with the safety distance d m as the radius and the connecting line of the relative position, and the included angle θ between the relative velocity vector and the relative position vector; S3 Judge whether the distance between our ship and the other ship satisfies being less than the collision detection distance CD. If it is satisfied, enter S4; S4 Judge whether the distance between our ship and the other ship is within the safety distance d m and the included angle θ between the relative velocity vector and the relative position vector; S3 Judge whether the distance between our ship and the other ship satisfies being less than the collision detection distance CD. If it is satisfied, enter S4; S4 Judge whether the distance between our ship and the other ship is within the safety distance d mIf the collision detection distance CD is satisfied, enter S5, if not, enter S6; S5 determines whether the angle between the speed vector of our ship and the speed vector of the other ship is less than the angle θ between the relative speed vector and the relative position vector, if so, a blue warning is issued; S6 calculates TCPA and DCPA, and determines 0<=TCPA<=TA and DCPA<=DA. If any condition is satisfied, an orange warning is issued; if both conditions are satisfied, a red warning is issued; if both conditions are not satisfied, enter S1.

[0066] Furthermore, in S2, the range distance R of our ship is calculated os The distance R between the ship and the area ts :

[0067] Convert the longitude and latitude coordinates of our ship and the other ship into northeast coordinates, find the equation of the line connecting our ship and the other ship, and use the equation of the line to combine with the ellipse equation of our ship and the ellipse equation of the other ship, and find the two intersection points of the equation of the line and the ellipse equation of our ship: Point 1 (x 1 ,y 1 ), point 2(x 2 ,y 2 ), find the two intersection points of the connecting line equation and the other ship's ellipse equation: point 3(x 3 ,y 3 ), point 4(x 4 ,y 4 );

[0068] Use the Pythagorean theorem to find the point 1(x 1 ,y 1 ) and point 2(x 2 ,y 2 ), point 3(x 3 ,y 3 ) and point 4(x 4 ,y 4 ) between the two sides;

[0069] Let the coordinates of my ship be O(x os ,y os ), the coordinates of the other ship are T(x ts ,y ts ), the line equation of the two ship positions OT equation:

[0070] y = k*x + d;

[0071] Joint:

[0072]

[0073] In the formula, θ 1 is the heading angle of our ship; θ 2 is the heading angle of the other ship; the slope of the straight line is The linear intercept is

[0074] Solve the equation to find point 1 (x 1 , y 1 ), point 2 (x 2 , y 2 ), point 3 (x 3 , y 3 ), point 4 (x 4 , y 4 );

[0075]

[0076] Furthermore, in S2, calculate the safety distance d between my ship and the other ship m :

[0077] d m = R os + d safe + R ts ;

[0078] In the formula, d safe is a distance determined by comprehensively considering the maneuvering performance, respective speeds, relative speed, and water area type of my ship and the other ship;

[0079] The calculation formula of d safe is:

[0080]

[0081] In the formula, timestep is the time step, with the unit of h; |vr| is the absolute value of the relative speed when my ship and the other ship are approaching each other, and 0 is taken when they are moving away from each other, with the unit of knot; T 90 is the time taken for the ship to turn 90° at full speed, with the unit of s; A d is the longitudinal distance moved by the center of gravity when the ship turns 90° at full speed, generally taking 2.8 - 4 times the ship length, with the unit of m; d nature is the safety distance required under natural conditions, generally taking 0.5 nautical miles, and can also be set according to experience; d water is the safety distance required for the water area where it is located, generally taking 0.5 nautical miles, and can also be set according to experience; μ n is the coefficient of d nature , with the minimum value of 0 and the maximum value of 1; μ w is the coefficient of d water , with the minimum value of 0 and the maximum value of 1.

[0082] Furthermore, among them, the calculation process of T 90 is obtained through the following method:

[0083] R = k 90 *L;

[0084] Wherein, R is the turning radius; k 90 takes values from 3 to 7, general merchant ships take values from 4 to 5, and large ships take values from 5 to 7; L is the ship length;

[0085] The turning radius is calculated using the angular velocity:

[0086]

[0087] Wherein, V is the ship speed; ω is the angular velocity;

[0088] The time taken to rotate by an angle of Δθ is:

[0089]

[0090] After arrangement:

[0091]

[0092] Therefore:

[0093]

[0094] Furthermore, in S2, calculate the angle θ m between the tangent of the circle with a radius of the safe distance d m and the connection line of the relative positions, as well as the angle θ between the relative velocity vector and the relative position vector:

[0095] In triangle OTS, θ m is equal to the arctangent function of d m and OS, and the magnitude of OS can be obtained through the Pythagorean theorem;

[0096] The magnitude of θ is obtained using the arccosine function of the dot product of the relative position vector OT and the relative position vector v ot point;

[0097] Therefore:

[0098]

[0099] Wherein, is the straight-line distance between ship O of our own and ship T of the other; is the position vector pointing from ship O of our own to ship T of the other;

[0100]

[0101] Wherein, is the relative velocity vector of ship O of our own relative to ship T of the other; is the dot product of the relative position vector and the relative velocity vector.

[0102] Further, in S3, calculate the collision detection distance CD:

[0103] CD = d m + ρ 0 ;

[0104] ρ 0 = max(fk * R ts , ρ 0min );

[0105] Set ρ 0 needs to consider two factors: (1) Overtaking situation: ρ 0min = 0.5 nautical miles; Crossing and head-on situations: ρ 0min = 1 nautical mile; (2) fk: Set by oneself, R ts : The domain distance of the other ship.

[0106] Further, in S6, calculate DCPA. DCPA is obtained through the sine function in triangle OTP:

[0107]

[0108] Calculate TCPA. The magnitude of TCPA is equal to the distance of PT divided by the magnitude of the speed in the PT direction. PT is obtained by using the cosine of the modulus of the relative position vector in triangle OTP:

[0109]

[0110] In the formula, is the magnitude of the relative speed, which is equal in magnitude to .

[0111] Further, in S5, if the condition is satisfied, then a blue warning is issued;

[0112] where distance is the distance between my ship and the other ship.

[0113] Further, in S6, if any of the conditions or is satisfied, then an orange warning is issued;

[0114] where DA is the semi-major axis of the ellipse equation of the other ship set; TA is the TCPA threshold set according to the empirical value.

[0115] Further, in S6, if both and are satisfied, then a red warning is issued.

[0116] Combined with Figure 1 andFigure 2 As shown in the figure, the research process of the present invention is as follows: First, the longitude and latitude space information of our ship and other ships is converted into the northeast coordinates in the northeast sky, where the east coordinate represents longitude and the north coordinate represents latitude. Then, the domain distance of the expanded ellipse between our ship and other ships, the safe distance d between our ship and other ships m , the distance between our ship and other ships, and the angle between the tangent of the circle with the safe distance d m as the radius and the connecting line of the relative positions, as well as the angle between the relative velocity vector and the relative position line are calculated. After calculating these parameters, it is started to judge whether the distance between our ship and other ships is less than the collision detection distance. If it is less, it is judged whether the distance between the two ships is between the safe distance and the collision detection distance. If so, it is continued to judge whether the angle between the two ship speed vectors is less than the angle between the relative velocity vector and the relative position line. If it is less, a blue warning is given. Otherwise, the risk situation between the two ships at the next moment is continued to be judged. If the distance between the two ships is less than or equal to the safe distance, the TCPA and DCPA values are calculated. If any of the conditions 0 <= TCPA <= TA or DCPA <= DA is satisfied, an orange warning is given. If both conditions are satisfied, a red warning is given. If neither condition is satisfied, the risk situation between the two ships at the next moment is continued to be judged.

[0117] As Figure 3 shown, the construction of the expanded ellipse model: The present invention is applied to every two ships. First, an expanded ellipse model is established for both our ship and other ships. Among them, the long axis direction of the ellipse is consistent with the ship length, and the short axis direction of the ellipse is consistent with the ship width direction. The center of the circle is the northeast coordinate in the northeast sky converted from the longitude and latitude coordinates. The calculation formula for the long semi-axis of the ellipse is:

[0118]

[0119] In the formula, the unit of a is m; L is the ship length, and the unit is m; v is the ship speed, and the unit is m / s; K is the proportionality coefficient.

[0120] The calculation formula for the short semi-axis of the ellipse is:

[0121]

[0122] In the formula, the unit of b is m; B is the ship width, and the unit is m.

[0123] In order to enable each ship to always maintain the expanded ellipse model at any position and any heading in the two-dimensional plane. Therefore, the ellipse formula:

[0124]

[0125] is modified to:

[0126]

[0127] The formula is obtained by rotating the ellipse clockwise by a certain angle θ with the center point of the ellipse (m, n) as the center of the circle, where θ can be understood as the heading angle.

[0128] like Figure 4 As shown, calculate the range distance R of our ship os The distance R between the ship and the area ts :Convert the longitude and latitude coordinates of our ship and the other ship into northeast coordinates, find the equation of the line connecting our ship and the other ship, and use the equation of the line to combine with the ellipse equation of our ship and the ellipse equation of the other ship, and find the two intersection points of the equation of the line and the ellipse equation of our ship: Point 1 (x 1 ,y 1 ), point 2(x 2 ,y 2 ), find the two intersection points of the connecting line equation and the other ship's ellipse equation: point 3(x 3 ,y 3 ), point 4(x 4 ,y 4 ); Use the Pythagorean theorem to find point 1(x 1 ,y 1 ) and point 2(x 2 ,y 2 ), point 3(x 3 ,y 3 ) and point 4(x 4 ,y 4 ) between the two.

[0129] Let the coordinates of my ship be O(x os ,y os ), the coordinates of the other ship are T(x ts ,y ts ), the line equation of the two ship positions OT equation:

[0130] y = k*x + d;

[0131] Joint:

[0132]

[0133] In the formula, θ 1 is the heading angle of our ship; θ 2 is the heading angle of the other ship; the slope of the straight line is The intercept of the line is

[0134] Solve the equation to find the point 1(x 1 ,y 1 ), point 2(x 2 ,y 2 ), point 3(x 3 ,y3 ) The point 4(x 4 , y 4 );

[0135]

[0136] As Figure 5 shown, calculate the safe distance d between our ship and the other ship m :

[0137] d m = R os + d safe + R ts ;

[0138] In the formula, d safe is a distance determined by comprehensively considering the maneuvering performance, respective speeds, relative speed, and water area type of our ship and the other ship;

[0139] d safe The calculation formula of is:

[0140]

[0141] In the formula, timestep is the time step, with the unit of h; |vr| is the absolute value of the relative speed when our ship and the other ship are approaching each other, and 0 is taken when they are moving away from each other, with the unit of knot; T 90 is the time taken for the ship to change the course angle by 90° during full-speed turning, with the unit of s; A d is the longitudinal distance moved by the center of gravity when the ship changes the course angle by 90° during full-speed turning, generally taking 2.8 - 4 times the ship length, with the unit of m; d nature is the safe distance required under natural conditions, generally taking 0.5 nautical miles, and can also be set according to experience; d water is the safe distance required for the water area where it is located, generally taking 0.5 nautical miles, and can also be set according to experience; μ n is the coefficient of d nature , with the minimum value of 0 and the maximum value of 1; μ w is the coefficient of d water , with the minimum value of 0 and the maximum value of 1.

[0142] Among them, the calculation process of T 90 is obtained through the following method:

[0143] R = k 90 * L;

[0144] In the formula, R is the turning radius; k 90 takes 3 - 7, ordinary merchant ships take 4 - 5, and large ships take 5 - 7; L is the ship length;

[0145] Calculating the turning radius using the angular velocity:

[0146]

[0147] Wherein, V is the ship speed; ω is the angular velocity;

[0148] The time taken to rotate by an angle Δθ is:

[0149]

[0150] After arrangement, we get:

[0151]

[0152] Therefore:

[0153]

[0154] Such as Figure 6 shown, calculating the angle θ between the tangent of the circle with a radius of safety distance d m and the connecting line of the relative positions m as well as the angle θ between the relative velocity vector and the relative position vector:

[0155] In triangle OTS, θ m is equal to the arctangent function of d m and OS. The magnitude of OS can be obtained through the Pythagorean theorem;

[0156] The magnitude of θ is obtained by the arccosine function of the dot product of the relative position vector OT and the relative position vector v ot point;

[0157] Therefore:

[0158]

[0159] Wherein, is the straight-line distance between our ship O and the other ship T; is the position vector pointing from our ship O to the other ship T;

[0160]

[0161] Wherein, is the relative velocity vector of our ship O relative to the other ship T; is the dot product of the relative position vector and the relative velocity vector.

[0162] Calculating the collision detection distance CD:

[0163] CD = d m + ρ 0 ;

[0164] ρ0 = max(fk * R ts , ρ 0min );

[0165] Set ρ 0 Two factors need to be considered: (1) Overtaking situation: ρ 0min = 0.5 nautical miles; Crossing and head-on situations: ρ 0min = 1 nautical mile; (2) fk: Set by yourself, R ts : The domain distance of the other ship.

[0166] Calculate DCPA, DCPA is obtained through the sine function in triangle OTP:

[0167]

[0168] As Figure 7 shown, calculate TCPA, the magnitude of TCPA is equal to the distance of PT divided by the magnitude of the speed in the direction of PT, and PT is obtained through the cosine of the modulus of the relative position vector in triangle OTP:

[0169]

[0170] In the formula, is the magnitude of the relative speed, which is equal to the magnitude.

[0171] Make a warning judgment according to the above parameters, and the judgment steps are as follows:

[0172] First step, at a certain moment, judge whether the distance distance between our ship and the other ship satisfies being less than the collision detection distance CD. If it is satisfied, enter the second step; if not, it means that there is no risk between our ship and the other ship at this time.

[0173] Second step, judge whether the distance distance between our ship and the other ship and the angle θ between the relative velocity vector and the relative position connection line satisfy the condition: If it is satisfied, issue a blue warning; if not, enter the third step.

[0174] Third step, judge whether the condition is satisfied. If any of the conditions is satisfied, issue an orange warning; if both conditions are satisfied, issue a red warning; if neither condition is satisfied, it means that there is no risk at this time, and the staff can decide whether to continue to judge the collision risk situation between our ship and the other ship at the next moment according to needs. Among them, DA is the major semi-axis of the ellipse equation of the other ship set; TA is the TCPA threshold set according to the empirical value.

[0175] In actual application, in the above formula, K takes the value of 1, tempstep takes the value of 1s, that is, 1 / 3600h, and k 90 takes the value of 5, and μ n takes 0, and μ w takes 1, and d nature and d water both take 0.5 nautical miles. When calculating A d 4 times the ship length is selected, and TA takes the value of 6min, that is, 360s.

[0176] Vessel 1: Longitude: 120.378757; Latitude: 38.184202; Ship length: 26m; Ship width: 6m; Speed: 7.2 knots; Course: 22.2 degrees;

[0177] Vessel 2: Longitude: 120.378147; Latitude: 38.198017; Ship length: 45m; Ship width: 7m; Speed: 6.3 knots; Course: 71.2 degrees;

[0178] After verification, the major semi-axis of the ellipse of Vessel 1 is 48.147839999999995 meters, and the minor semi-axis is 11.11104 meters. The major semi-axis of the ellipse of Vessel 2 is 72.91619999999999 meters, and the minor semi-axis is 11.342519999999999 meters. The domain distance R of Vessel 1 os is 26.89352819116253 meters, and the domain distance R of Vessel 2 ts is 12.079561607092643 meters. The safety distance d m is 973.336729557318 meters, the collision detection distance CD of Vessel 2 is 2825.336729557318 meters, the distance between the two vessels distance is 1537.198175041334 meters, θ is 0.5829270545885261, and θ m is 0.6856662660393456. The distance between the two vessels distance is greater than the safety distance d m and less than the collision detection distance CD of Vessel 2, and θ is less than θ m , so a blue warning is issued.

[0179] Vessel 3: Longitude: 120.385813; Latitude: 38.19986; Ship length: 26m; Ship width: 6m; Speed: 7.5 knots; Course: 19 degrees;

[0180] Vessel 4: Longitude: 120.384; Latitude: 38.199547; Ship length: 45m; Ship width: 7m; Speed: 7.1 knots; Course: 71.3 degrees;

[0181] After verification, the major semi - axis of the ellipse of our ship is 50.153999999999996 meters, and the minor semi - axis is 11.573999999999998 meters. The major semi - axis of the ellipse of the other ship is 82.17539999999998 meters, and the minor semi - axis is 12.782839999999998 meters. The domain distance R of our ship os is 11.656582226698841 meters, and the domain distance R of the other ship ts is 24.229729241981012 meters. The safety distance d m is 970.0402063521217 meters. The collision detection distance CD of the other ship is 2822.0402063521215 meters. The distance between the two ships, distance, is 162.2154077901397 meters. DA is 82.17539999999998 meters, DCPA is 140.94667906038777 meters, and TCPA is 12.45990846021347 seconds. The distance between the two ships, distance, is less than the safety distance d m and 0 ≤ TCPA ≤ TA, so an orange warning is issued.

[0182] Our ship 3: Longitude: 120.38492; Latitude: 38.197902; Length: 26m; Width: 6m; Speed: 7.6 knots; Course: 10.7 degrees;

[0183] The other ship 3: Longitude: 120.384; Latitude: 38.199547; Length: 45m; Width: 7m; Speed: 7.1 knots; Course: 71.3 degrees;

[0184] After verification, the major semi - axis of the ellipse of our ship is 50.82272 meters, and the minor semi - axis is 11.728319999999998 meters. The major semi - axis of the ellipse of the other ship is 82.17539999999998 meters, and the minor semi - axis is 12.782839999999998 meters. The domain distance R of our ship os is 37.379055720168864 meters, and the domain distance R of the other ship ts is 17.039938650551463 meters. The safety distance d m is 989.0793845746355 meters. The collision detection distance CD of the other ship is 2841.0793845746357 meters. The distance between the two ships, distance, is 199.8170662630768 meters. DA is 82.17539999999998 meters, DCPA is 75.97795969562506 meters, and TCPA is 24.87627586457624 seconds. The distance between the two ships, distance, is less than the safety distance d mAnd the DCPA is less than DA, and 0 ≤ TCPA ≤ TA, so a red warning is issued.

[0185] In the present invention, the blue warning, orange warning, and red warning do not specifically limit the color or form of the warning, but are used to distinguish the warning level or the urgency of the warning. Among them, the urgency of the red warning is greater than that of the orange warning, and the urgency of the orange warning is greater than that of the blue warning.

[0186] Certainly, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions, or substitutions made by those skilled in the art within the scope of the essence of the present invention should also fall within the protection scope of the present invention.

Claims

1. A ship warning method based on an expanded ellipse and expanded circle model, characterized in that: The following steps are involved: S1 obtains the latitude and longitude, speed and heading information of our ship and other ships, establishes a rectangular coordinate system, and establishes an expanded ellipse model of our ship and other ships; S2 calculates the area distance of the expansion ellipse of our ship and the other ship, and the safe distance d between our ship and the other ship m , the distance between our ship and the other ship, the safe distance d m The angle θ between the tangent line of the circle with radius and the line connecting the relative positions m and the angle θ between the relative velocity vector and the line connecting the relative position; S3 determines whether the distance between the ship and the other ship is less than the collision detection distance CD. If so, enter S4; S4 determines whether the distance between our ship and other ships is within a safe distance d m If the collision detection distance CD is satisfied, the process goes to S5; if not, the process goes to S6; S5 determines whether the angle θ between the relative velocity vector of our ship and the relative position line of the other ship is less than the safety distance d m The angle θ between the tangent line of the circle with radius and the line connecting the relative positions m , if it is met, a blue warning will be issued; S6 calculates TCPA and DCPA, and determines whether 0<=TCPA<=TA and DCPA<=DA. If any of the conditions is met, an orange warning is issued; If both conditions are met, a red alert is issued; If both conditions are not met, enter S1; In S2, calculate the range distance R of our ship os The distance R between the ship and the area ts : Convert the longitude and latitude coordinates of our ship and the other ship into northeast coordinates, find the equation of the line connecting our ship and the other ship, use the equation of the line to respectively combine with the ellipse equation of our ship and the ellipse equation of the other ship, find the two intersection points of the line equation and the ellipse equation of our ship: point 1 (x1, y1), point 2 (x2, y2), find the two intersection points of the line equation and the ellipse equation of the other ship: point 3 (x3, y3), point 4 (x4, y4); Use the Pythagorean theorem to find the distance between point 1 (x1, y1) and point 2 (x2, y2), and the distance between point 3 (x3, y3) and point 4 (x4, y4); Calculate the safe distance d between our ship and other ships m : d m =R os +d safe +R ts ; Where, d safe It is a distance determined by comprehensively considering the maneuverability of our ship and other ships, their respective speeds, relative speeds and water type conditions.

2. The ship warning method based on the puffed ellipse and puffed circle model according to claim 1 is characterized in that: Let the coordinates of my ship be O(x os ,y os ), the coordinates of the other ship are T(x ts ,y ts ), the line equation of the two ship positions OT equation: y=k*x+d; Joint: In the formula, θ1 is the heading angle of our ship; θ2 is the heading angle of the other ship; the slope of the straight line is The intercept of the line is Solve the equation to find point 1 (x1, y1), point 2 (x2, y2), point 3 (x3, y3), and point 4 (x4, y4); 3. The ship early warning method based on the puffed ellipse and puffed circle model according to claim 2 is characterized in that: d safe The calculation formula is: Where timestep is the time step, in h; |vr| is the absolute value of the relative speed between our ship and the other ship when they are approaching each other, and is 0 when they are moving away from each other, in knots; T 90 It is the time taken by the ship to turn at full speed and change the heading angle by 90°, in seconds; A d It is the longitudinal distance that the center of gravity moves when the ship turns at full speed and the heading angle changes by 90°, which is 2.8 to 4 times the length of the ship, in meters; d nature The safety distance required under natural conditions is 0.5 nautical miles; d water The required safety distance in the waters is 0.5 nautical miles; μ n is d nature The coefficient of μ is 0 at the minimum and 1 at the maximum. w is d water The minimum value is 0 and the maximum value is 1.

4. The ship warning method based on the puffed ellipse and puffed circle model according to claim 3 is characterized in that: in, T 90 The calculation process of is obtained in the following way: R=k 90 *L; Where R is the gyration radius; k 90 The value is 3 to 7, ordinary merchant ships are 4 to 5, and large ships are 5 to 7; L is the length of the ship; Use the angular velocity to calculate the radius of gyration: Where V is the ship speed; ω is the angular velocity; The time taken to rotate the angle Δθ is: Arranged: Therefore:

5. The ship warning method based on the puffed ellipse and puffed circle model according to claim 4 is characterized in that: In S2, the safe distance d is calculated. m The angle θ between the tangent line of the circle with radius and the line connecting the relative positions m And the angle θ between the relative velocity vector and the relative position vector: In the triangle OTS, θ m Equal to d m The inverse tangent function of OS, the size of OS can be calculated by the Pythagorean theorem; The magnitude of θ is expressed by the relative position vector OT and the relative position vector v ot The arccosine function of the dot product is found; Therefore: In the formula, is the straight-line distance between our ship O and his ship T; is the position vector of my ship O pointing to his ship T; In the formula, is the relative velocity vector of our ship O relative to the other ship T; is the dot product of the relative position vector and the relative velocity vector.

6. The ship warning method based on the puffed ellipse and puffed circle model according to claim 5 is characterized in that: In S3, calculate the collision detection distance CD: CD=d m +ρ0; ρ0=max(fk*R ts ,r 0min ); There are two factors to consider when setting ρ0: (1) Overtaking situation: ρ 0min =0.5 nautical miles; Crossing and encounter situations: ρ 0min = 1 nautical mile; (2), fk: set by yourself, R ts : The distance to his ship's territory.

7. The ship warning method based on the puffed ellipse and puffed circle model according to claim 6 is characterized in that: In S6, DCPA is calculated, which is obtained by the sine function in the triangle OTP: Calculate TCPA. The magnitude of TCPA is equal to the distance of PT divided by the velocity in the PT direction. PT is obtained by taking the cosine of the modulus of the relative position vector through the triangle OTP: In the formula, is the magnitude of the relative velocity, and Equal in size.

8. The ship warning method based on the puffed ellipse and puffed circle model according to claim 7 is characterized in that: In S5, the condition is met A blue alert is issued; Among them, distance is the distance between my ship and the other ship.

9. The ship warning method based on the puffed ellipse and puffed circle model according to claim 8 is characterized in that: In S6, any of the conditions is met or An orange alert is issued; Among them, DA is the major semi-axis of the set ellipse equation of the other ship; TA is the TCPA threshold set according to the empirical value.

10. The ship warning method based on the puffed ellipse and puffed circle model according to claim 9 is characterized in that: In S6, both and A red alert is issued.

Images