Method and system for determining the roll angle of a fishing vessel under wave action

Abstract

The application provides a method and system for determining the roll angle of a fishing ship under the action of waves, the method comprising: obtaining ship parameters of a target fishing ship and wave environment parameters of a target sea area; calculating dimensionless parameters according to the ship parameters and the wave environment parameters, the dimensionless parameters including relative ship speed, wave steepness, relative ship width and heading angle radian value; selecting a corresponding roll angle calculation model according to the length range of the target fishing ship; and substituting the dimensionless parameters into the selected roll angle calculation model to calculate the roll angle of the target fishing ship. The application can quickly and accurately calculate the roll angle of the fishing ship based on real-time sailing and wave parameters, realize risk warning and heading optimization, and significantly improve the safety and operation efficiency of the fishing ship sailing.

Description

Technical Field

[0001] This invention relates to the technical field of determining the roll angle of fishing vessels, specifically to a method and system for determining the roll angle of a fishing vessel navigating under wave action. Background Technology

[0002] Fishing vessels operating at sea experience a series of complex motions, including rolling, pitching, and heaving, under the influence of waves, which can even lead to capsizing and other maritime accidents. Roll angle (the degree of lateral rolling) is a crucial indicator, directly impacting crew comfort and operational efficiency. Excessive roll angle forces crew members to spend extra time maintaining balance due to loss of equilibrium, reducing work efficiency. Furthermore, increased roll angle can interfere with the normal operation of radar and other instruments, and may even cause the vessel to capsize. While some progress has been made in theoretical calculations of ship seakeeping, the development of seakeeping standards for fishing vessels, hull optimization, and motion response prediction—such as the two-dimensional slice theory proposed by Korvin-Kroukovsky and Jacober, the six-degree-of-freedom coupled motion equations for ships in regular waves established by Xiong Wenhai, and Tello's seakeeping assessments of fishing vessels of various sizes—existing methods still have some shortcomings.

[0003] First, there is a lack of simple, fast, and real-time quantitative models for the rolling motion of typical coastal fishing vessels under wave action, especially the rolling response under the coupled influence of heading, speed, and wave parameters (wave height, wave period). Second, existing theoretical calculations are complex and difficult to embed into shipborne early warning systems. Third, existing methods lack a unified mathematical expression for the combined effects of multiple factors such as relative ship speed, wave steepness, relative ship width, and heading, making it difficult to achieve rapid prediction of rolling angles and risk classification early warning. Summary of the Invention

[0004] The purpose of this invention is to provide a method and system for determining the roll angle of a fishing vessel under wave action, so as to solve the problems of complex calculation models for the roll of fishing vessels, difficulty in real-time operation, and lack of unified expression of multi-factor coupling in the existing technology.

[0005] According to a first aspect of the present invention, a method for determining the roll angle of a fishing vessel navigating under wave action is provided, the method comprising: Obtain the vessel parameters of the target fishing vessel and the wave environment parameters of the target sea area; Dimensionless parameters are calculated based on the ship parameters and the wave environment parameters. The dimensionless parameters include relative ship speed, wave steepness, relative ship width, and heading angle in radians. Select the corresponding roll angle calculation model based on the range of lengths of the target fishing vessel; The dimensionless parameters are substituted into the selected roll angle calculation model to calculate the roll angle of the target fishing vessel.

[0006] According to a second aspect of the present invention, a system for determining the roll angle of a fishing vessel navigating under wave action is provided, comprising: The parameter acquisition module is used to acquire the vessel parameters of the target fishing vessel and the wave environment parameters of the target sea area; The parameter processing module is used to calculate dimensionless parameters based on the ship parameters and the wave environment parameters. The dimensionless parameters include relative ship speed, wave steepness, relative ship width, and heading angle in radians. The model matching module is used to select the corresponding roll angle calculation model according to the length range of the target fishing vessel; The roll angle calculation module is used to substitute the dimensionless parameters into the selected roll angle calculation model to calculate the roll angle of the target fishing vessel.

[0007] Compared with existing technologies, this invention has the following significant advantages: 1. It only requires input of basic ship parameters and real-time wave environment parameters, and can output the roll angle of the sailing ship in real time through parameter dimensionlessness and formula calculation, with low computational load, suitable for real-time operation of shipborne equipment; 2. Based on a large number of actual ship or physical model tests and data regression methods, the established mathematical formula can comprehensively reflect the nonlinear coupling influence of factors such as relative ship speed, wave steepness, relative ship width, and heading angle on the roll angle; it has been verified that for typical fishing vessels, the correlation coefficient R between the calculated value and the measured value is [value missing]. 2 It can reach over 0.95, which is significantly better than existing empirical estimation methods; 3. By setting the roll angle safety threshold, it can realize three-level early warning of roll risk (green, yellow, and red) and provide optimal course suggestions to support crew decision-making and improve navigation safety. Attached Figure Description

[0008] Figure 1 A flowchart illustrating a method for determining the roll angle of a fishing vessel navigating under wave action, provided in an embodiment of the present invention;

[0009] Figure 2 This is a schematic diagram illustrating the relationship between relative ship speed and roll angle in this invention.

[0010] Figure 3 This is a schematic diagram illustrating the relationship between wave steepness and roll angle in this invention;

[0011] Figure 4 This is a schematic diagram illustrating the relationship between the relative ship width and the roll angle in this invention;

[0012] Figure 5 This is a schematic diagram illustrating the relationship between the heading angle and the roll angle in this invention.

[0013] Figure 6This is a scatter plot showing the comparison between the calculated and measured values ​​of the roll angle of this invention. Detailed Implementation

[0014] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of this application.

[0015] Example 1

[0016] Reference Figure 1 , Figure 1 This is an overall flowchart of a method for determining the roll angle of a fishing vessel navigating under wave action, according to an embodiment of this application. The determination method may include the following steps:

[0017] Step S1: Obtain the vessel type parameters and wave environment parameters of the target sea area. The vessel type parameters must include at least the vessel length. L pp , width B Draft d and sailing speed v Wave environment parameters include at least the significant wave height. H Mean wave period T and heading angle θ In some embodiments, wave environment parameters can be acquired in real time via shipborne wave sensors or marine weather forecast data receiving modules; ship speed... v Heading angle can be obtained via shipboard GPS or odometer. θ It can be obtained through a shipboard compass or attitude sensor.

[0018] Step S2: Calculate dimensionless parameters based on the ship parameters and the wave environment parameters. These dimensionless parameters include relative ship speed, wave steepness, relative ship beam, and heading angle in radians. This step may specifically include:

[0019] S201, according to the formula Calculate relative ship speed V s ,in g Represents gravitational acceleration. v Indicates sailing speed. d Indicates draft;

[0020] S202, according to the formula Calculate wave steepness ,in H Indicates the significant wave height. LIndicates wavelength. , T Indicates the average wave period;

[0021] S203, according to the formula λ = L / B Calculate the relative ship beam λ ,in B Indicates the width;

[0022] S204, according to the formula θ rad = θ × π / 180 Calculate the heading angle in radians θ rad ,in θ Indicates the heading angle. θ Input in degrees. θ rad The unit is radians.

[0023] Step S3: Select the corresponding roll angle calculation model according to the length range of the target fishing vessel.

[0024] Specifically, if the captain of the target fishing vessel L pp If the length is greater than 25 meters, then the first roll angle calculation model should be selected; if the length of the target fishing vessel is... L pp If the distance is ≤ 25 meters, then the second roll angle calculation model should be selected.

[0025] Both the first roll angle calculation model and the second roll angle calculation model have the following forms:

[0026] ;

[0027] in, R Indicates the roll angle. V s Indicates relative ship speed. λ Indicates the relative width of the ship. A i Represents the radian value of the heading angle. θ rad Related coefficient terms, α i , β i , γ i This represents pre-stored coefficients, which are constants determined through extensive real-ship or physical model tests and data regression methods.

[0028] coefficient term A iThe calculation method is as follows:

[0029] For the calculation model of the first roll angle: A 1 = 530 - 140cos(4.57 θ rad - 290sin(3.45) θ rad );

[0030] For the second roll angle calculation model: A 2 = 640 - 250cos(2.94 θ rad ) - 200sin(2.56 θ rad );

[0031] in, θ rad This indicates the heading angle in radians.

[0032] Step S4: Substitute the dimensionless parameter into the selected roll angle calculation model to calculate the roll angle of the target fishing vessel.

[0033] Specifically, relative ship speed V s steep waves Relative ship width λ and heading angle in radians θ rad Substituting the values ​​into the selected roll angle calculation model, the roll angle of the target fishing vessel is calculated. R The unit is degrees (°).

[0034] Step S5: Compare the roll angle with the preset roll angle threshold, and issue a risk classification warning based on the comparison result.

[0035] Specifically, if the roll angle R Less than the safe roll angle threshold R safe If the condition is met, it is considered a safe state and a green notification is displayed.

[0036] If the lateral tilt angle R Greater than or equal to the safe roll angle threshold R safe And less than the dangerous roll angle threshold R warm If the situation is as described above, it will be considered a state of alert and a yellow warning will be issued indicating the presence of turbulence.

[0037] If the lateral tilt angle R Greater than or equal to the danger roll angle threshold R warmIf the situation is deemed dangerous, a red warning for roll risk will be issued, and it will be recommended to adjust the course or reduce the speed.

[0038] Step S6: When a dangerous situation is determined, perform heading optimization. Heading optimization includes: based on the current heading angle... θ Within a range of ±30 degrees, a set of candidate headings is generated with a preset step size, and the predicted roll angle corresponding to each candidate heading is calculated. The heading with the smallest predicted roll angle is recommended as the optimized heading.

[0039] Specifically, when a dangerous situation is determined, an automatic course optimization step is executed:

[0040] S601, Based on the current heading angle θ ,exist θ A candidate heading set is generated in 5° increments within a range of ±30°; the range of ±30° limits the maximum magnitude of heading adjustment to prevent drastic changes in the ship's roll response or loss of control caused by excessively large changes in heading angle.

[0041] S602. For each candidate heading, repeat steps S2-S4 (changing only the heading angle while keeping other parameters unchanged) to calculate the corresponding predicted roll angle. R pre .

[0042] S603, Select the predicted roll angle R pre The smallest candidate course is selected as the optimal course. θ pot The corresponding roll angle at this time is R pot It also provides a suggestion: Adjust the heading to... θ pot The roll angle is expected to be reduced to [degrees]. R pot Spend.

[0043] Example 2

[0044] This embodiment provides a system for determining the roll angle of a fishing vessel under wave action. It can be deployed in the ship's central control unit or onboard embedded equipment using a modular structure. The system can include a parameter acquisition module, a parameter processing module, a model matching module, a roll angle calculation module, and an early warning and optimization module.

[0045] The parameter acquisition module is used to acquire the vessel parameters of the target fishing vessel and the wave environment parameters of the target sea area.

[0046] The parameter acquisition module may include multiple sensor interfaces and data receiving units, such as a shipborne wave sensor or marine weather forecast data receiving module for real-time acquisition of wave environment parameters; a shipborne GPS or log for real-time acquisition of the target fishing vessel's speed; and a shipborne compass or attitude sensor for real-time acquisition of the target fishing vessel's heading angle. Here, the heading angle refers to the angle between the wave propagation direction and the vessel's heading, with 0 degrees for headwinds and 90 degrees for crosswinds. In practical applications, since the ship's roll motion is usually minimal and negligible when headwinds (near 0 degrees), this application limits the calculated heading angle value to between 15 and 90 degrees to improve computational efficiency and model specificity.

[0047] The parameter processing module is used to calculate dimensionless parameters based on the ship parameters and the wave environment parameters. The dimensionless parameters include relative ship speed, wave steepness, relative ship width, and heading angle in radians.

[0048] By transforming the input physical parameters into dimensionless parameters, subsequent mathematical calculations are greatly simplified, and the model's generalization ability is improved. Specifically, the parameter processing module can be used to calculate relative ship speeds. V s steep waves Relative ship width λ and heading angle in radians θ rad Four dimensionless parameters.

[0049] According to the formula Calculate relative ship speed V s ,in g Represents gravitational acceleration. v Indicates sailing speed. d Indicates draft; relative speed V s It is a dimensionless number that comprehensively reflects the relative relationship between ship speed and ship draft, and can more scientifically characterize the ship's motion state in the medium.

[0050] According to the formula Calculate wave steepness ,wavelength ,in T Indicates the average wave period. H Indicates significant wave height; wave steepness It is an important dimensionless parameter characterizing the degree of distortion of wave geometry and the degree of energy concentration, and has a significant impact on the rolling excitation moment of a ship.

[0051] According to the formula λ = L / B Calculate the relative ship beamλ ,in B The wavelength is indicated by the ship's width; when the wavelength is in a specific ratio to the ship's width, the ship is prone to severe rolling resonance, therefore, relative to the ship's width... λ It is an indispensable dimensionless parameter for predicting the roll angle.

[0052] According to the formula θ rad = θ × π / 180 Calculate the heading angle in radians θ rad ,in θ Indicates the heading angle. θ Input in degrees. θ rad The unit is radians.

[0053] The model matching module is used to select the corresponding roll angle calculation model based on the length range of the target fishing vessel.

[0054] Fishing vessels of different lengths exhibit significantly different motion response characteristics in waves. For example, fishing vessels longer than 25 meters (typically large or medium-sized coastal or deep-sea fishing vessels) have larger moments of inertia and different natural periods, while fishing vessels shorter than or equal to 25 meters (typically small coastal fishing vessels) are more sensitive to waves and are highly susceptible to wave moments. Using a uniform empirical formula would inevitably lead to excessively large calculation errors for certain types of fishing vessels.

[0055] To overcome this limitation, the model matching module can pre-set at least two empirical models corresponding to different ship types, each corresponding to a first ship length range ( L pp >25m) and the second ship length range ( L pp ≤25m). When the model matching module determines the length of the target fishing vessel... L pp If the value is greater than 25 meters, the first roll angle calculation model is activated, and the roll angle calculation module is notified to load the pre-stored first set of coefficients. α 1. β 1. γ 1) If the length of the target fishing vessel is determined... L pp If the value is less than or equal to 25 meters, the second roll angle calculation model can be activated, and the roll angle calculation module will be notified to load the pre-stored second set of coefficients. α 2. β 2. γ 2). This design based on the length classification selection model ensures both the simplicity of calculation and significantly improves the calculation accuracy for fishing vessels of different sizes.

[0056] The roll angle calculation module is used to substitute the dimensionless parameters into the selected roll angle calculation model to calculate the roll angle of the target fishing vessel. By employing an empirical formula derived through regression optimization using extensive experimental data, the roll angle calculation module can achieve high-precision real-time prediction of the roll angle with extremely low computational cost.

[0057] In some embodiments, when the model matching module selects the first roll angle calculation model, the roll angle is calculated using the following formula. R (Unit: degrees):

[0058] ;

[0059] in, R Indicates the roll angle. V s Indicates relative ship speed. λ Indicates the relative width of the ship. A 1 represents the radian value of the first roll angle calculation model compared to the heading angle. θ rad Related coefficient terms, α 1. β 1. γ 1 represents the first set of pre-stored coefficients, which are constants determined by multivariate nonlinear regression analysis of a large number of large and medium-sized fishing vessels (ship length greater than 25 meters) on actual ship navigation data and physical model pool test data.

[0060] For example, in some preferred embodiments, the coefficient can be set as follows for the first ship length range: α 1 = 1.01, β 1 = 1.02, γ 1 = 0.46. However, this application is not limited to this; these coefficients can be fine-tuned according to the specific hull shape of different fishing vessels or the wave characteristics of specific sea areas.

[0061] A 1 can be calculated using the following formula: A 1 = 530 - 140cos(4.57 θ rad - 290sin(3.45) θ rad );

[0062] in, θ rad This indicates the heading angle in radians.

[0063] In some embodiments, when the model matching module selects the second roll angle calculation model, the roll angle is calculated using the following formula. R : ;

[0064] in, A 2 represents the radian value of the heading angle under the second roll angle calculation model. θ rad The relevant coefficients can be calculated using the following formula:

[0065] A 2 = 640 - 250cos(2.94 θ rad ) - 200sin(2.56 θ rad ).

[0066] In the above formula, α 2. β 2. γ 2 represents a pre-stored second set of coefficients. These coefficients are constants determined through regression analysis of experimental data from a large number of small fishing vessels (length less than or equal to 25 meters). For example, in some preferred embodiments, the coefficients can be set as follows for a second vessel length range: α 2 = 0.95, β 2 = 1.15, γ 2 = 0.27. Similarly, these coefficients can also be adaptively adjusted according to the actual application scenario.

[0067] The formulas used in the roll angle calculation module nonlinearly couple wave steepness, relative ship beam, relative ship speed, and heading angle in radians. The power function term in the formula reflects the characteristic that the ship's roll response gradually increases with increasing relative ship speed and wave steepness; the exponential square decay term reflects the characteristic that the ship's roll response gradually decreases with increasing relative ship beam; and the heading angle in radians... θ rad Related coefficient terms A 1 and A The trigonometric function combination in section 2 can capture the variation law of roll moment under different wave directions (such as obliquely facing waves, cross waves, and obliquely with waves): the roll angle first increases and then decreases with the increase of the heading angle, and reaches its maximum when the heading angle reaches 75 degrees.

[0068] The early warning optimization module is used to compare the roll angle with a preset threshold to output the risk level. When the state is determined to be dangerous, it generates a set of candidate headings within a preset step size of ±30 degrees based on the current heading angle, calculates the predicted roll angle corresponding to each candidate heading, and recommends the heading with the smallest predicted roll angle as the optimized heading.

[0069] Specifically, the early warning optimization module can implement a three-level safety early warning mechanism: green, yellow, and red. The real-time roll angle output by the roll angle calculation module... R With the preset safe roll angle threshold R safe and dangerous roll angle threshold R warm A comparison is made. In some embodiments, the safe roll angle threshold is... R safe It can be preset to 5 degrees, the dangerous roll angle threshold. R warm The threshold can be preset to 10 degrees. These thresholds can be adjusted individually based on the specific type of fishing operation (such as trawling, purse seine, drift gillnetting, etc.), cargo status (empty or fully loaded), and the crew's tolerance level.

[0070] When determining the calculated roll angle R Less than the safe roll angle threshold R safe When the ship is in a safe position, it indicates that the current motion of the vessel is very safe and the crew can carry out their work normally. At this time, the ship can be determined to be in a safe state, and a green prompt message will be output through the ship's onboard display terminal, such as: Navigation safe, roll normal.

[0071] When determining the roll angle R Greater than or equal to the safe roll angle threshold R safe And less than the dangerous roll angle threshold R warm When this occurs, it indicates that the ship is beginning to experience significant rolling, reducing crew comfort, increasing operational difficulty, and posing certain safety hazards. At this point, the ship can be determined to be in a state of alert and will issue a yellow warning for turbulence, such as by flashing yellow text on the display screen or emitting a soft buzzing sound, to remind the crew: the ship is turbulent, be aware of slippage, and operate with caution.

[0072] When determining the roll angle R Greater than or equal to the danger roll angle threshold R warm When the ship rolls violently, it indicates that the ship is in a dangerous state, which could easily lead to waves on deck, cargo displacement, crew injuries, and even capsizing. A red roll risk warning will be issued. A red roll warning may include a high-decibel alarm, a bright flashing red screen, and the text message: "Danger! Excessive rolling, please adjust course or reduce speed immediately!"

[0073] At the same time, the early warning optimization module initiates the automatic course optimization process.

[0074] When the early warning optimization module determines that the ship is in a dangerous state, it can adjust the current heading angle.θ Based on this, a set of candidate headings is generated within a range of ±30 degrees, with a step size of 5 degrees. For example, if the current heading angle is 60 degrees, the generated set of candidate headings could include: 30 degrees, 35 degrees, 40 degrees, 45 degrees, 50 degrees, 55 degrees, 60 degrees (original heading), 65 degrees, 70 degrees, 75 degrees, 80 degrees, 85 degrees, and 90 degrees. Limiting the search range to ±30 degrees is to prevent loss of ship control or violent transient motions caused by excessively large changes in heading angle. Using a step size of 5 degrees ensures both search precision and control of computational load, ensuring calculations are completed within milliseconds.

[0075] Next, for each candidate course in the candidate course set, while keeping other parameters (such as ship speed, wave height, wave period, etc.) constant, the predicted roll angle corresponding to each candidate course can be calculated. R pre Finally, the candidate course that minimizes the predicted roll angle is selected as the optimal course. θ pot The corresponding minimum predicted roll angle at this time is R pot It also outputs specific heading adjustment suggestions, such as displaying on the terminal: "It is recommended to adjust the heading to..." θ pot The roll angle is expected to be reduced to [degrees]. R pot The crew or autopilot system can make minor course adjustments based on this recommendation, allowing the vessel to quickly escape a dangerous situation.

[0076] Example 3

[0077] To enable those skilled in the art to more clearly understand the technical solution and practical effects of this application, a detailed description is provided below with reference to specific numerical embodiments. In the first specific embodiment, a 32-meter fishing boat sailing along the coast of Fujian is taken as an example. The hull parameters and real-time wave environment parameters of the fishing boat are as follows:

[0078] Captain of the target fishing vessel L pp It can be approximately 32 meters long, with a width of... B It can be approximately 6.7 meters in length, with a draft of [missing information]. d It can be approximately 3.1 meters, at the current sailing speed. v It can be approximately 4.12 m / s (about 8 knots). The real-time wave environment parameters for the target sea area are: significant wave height. H It can be approximately 2.5 meters, with an average wave period. T It can be approximately 6 seconds, the current heading angle θ It can be approximately 60 degrees.

[0079] S1. Calculate the dimensionless parameters.

[0080] (1) Calculate the wavelength L : = 1.56 × 36 = 56.16 meters.

[0081] (2) Calculate the relative ship speed V s : ≈ 0.747.

[0082] (3) Calculate wave steepness : = H / L = 2.5 / 56.16 ≈ 0.0445.

[0083] (4) Calculate the relative ship beam λ : λ = L / B = 56.16 / 6.7 ≈ 8.382.

[0084] (5) Calculate the heading angle in radians θ rad : θ rad = θ × π / 180 = 60 × 3.1415926 / 180 ≈ 1.047 radians.

[0085] S2. Select the roll angle calculation model.

[0086] Due to the captain of the target fishing vessel L pp = 32 meters, which is greater than the preset threshold of 25 meters. Therefore, the fishing vessel is determined to be within the first length range. The first roll angle calculation model is selected, and the first set of coefficients is loaded: α 1 = 1.01, β 1 = 1.02, γ 1 = 0.46.

[0087] S3. Calculate the roll angle. R .

[0088] First, calculate the radian value of the first roll angle calculation model relative to the heading angle. θ rad Related coefficient terms A 1:

[0089] A 1 = 530 - 140cos(4.57 θ rad- 290sin(3.45) θ rad )≈651.

[0090] ≈ 8.94 degrees.

[0091] S4. Conduct risk classification and early warning.

[0092] Calculated roll angle R The value is approximately 8.94 degrees, which is compared to a preset threshold. Because... R safe = 5 degrees, R warm = 10 degrees, the current roll angle satisfies the relationship: 5 degrees ≤ R <10 degrees. Therefore, the system determines that the vessel is currently in a state of alert, and issues a yellow warning for turbulence on the bridge terminal to remind the crew to pay attention to safety. However, since the situation has not reached a dangerous state, the course optimization process is not triggered.

[0093] Example 4

[0094] In the second specific embodiment, the same 32-meter fishing vessel as in Embodiment 3 was used, but this vessel encountered more severe sea conditions during its voyage. The hull parameters of the target fishing vessel remained unchanged: length L pp = 32 meters, width B = 6.7 meters, draft d = 3.1 meters, speed v = 4.12 m / s. The real-time acquired parameters for the severe wave environment are: significant wave height. H It can be approximately 5.0 meters (wave height doubled), with an average wave period of... T It can be approximately 7 seconds, the current heading angle θ It can still be around 60 degrees.

[0095] S1. Calculate the dimensionless parameters.

[0096] (1) Calculate the wavelength L : =1.56×49= 76.44 meters.

[0097] (2) Calculate the relative ship speed V s : ≈ 0.747.

[0098] (3) Calculate the wave steepness : = H / L= 5.0 / 76.44 ≈ 0.0654.

[0099] (4) Calculate the relative ship beam λ : λ = L / B = 76.44 / 6.7 ≈ 11.409.

[0100] (5) Calculate the heading angle in radians θ rad : θ rad = θ × π / 180 = 60×3.1415926 / 180 ≈1.047 radians.

[0101] S2. Select the roll angle calculation model.

[0102] Due to the captain L pp = 32 meters, greater than 25 meters, still choose the first roll angle calculation model, with coefficients of α 1 = 1.01, β 1 = 1.02, γ 1 = 0.46.

[0103] S3. Calculate the roll angle. R .

[0104] coefficient term A 1 remains unchanged, still approximately 651.

[0105] Substitute the new dimensionless parameter into the first roll angle calculation model: ≈12.94 degrees.

[0106] S4. Conduct risk classification and early warning.

[0107] Calculated roll angle R It is approximately 12.70 degrees, which is compared to a preset threshold. Because... R =12.94 degrees≥ R warm =10 degrees, indicating the vessel is in a dangerous state. Immediately issue a red roll risk warning on the bridge, sound the audible and visual alarms loudly, and display a flashing red image on the screen. Simultaneously, automatically trigger the course optimization execution steps.

[0108] S5. Perform automatic heading optimization.

[0109] At the current heading angle θBased on a base of 60 degrees, a candidate heading set is generated within a range of ±30 degrees (i.e., 30 to 90 degrees) in steps of 5 degrees. The generated candidate heading set is as follows: {30°, 35°, 40°, 45°, 50°, 55°, 60°, 65°, 70°, 75°, 80°, 85°, 90°}.

[0110] Then, keeping other parameters constant and only changing the heading angle, the predicted roll angle for each candidate heading is calculated sequentially. R pre The calculation results are shown in Table 1 below:

[0111] Table 1. Predicted roll angles under different candidate headings 30 6.96 35 8.19 40 9.45 45 10.62 50 11.62 55 12.39 60 (original heading) 12.94 65 13.28 70 13.46 75 13.52 80 13.49 85 13.37 90 13.17

[0112] S6. Predicted roll angle for all the above candidate headings R pre A comparison was made. It is clear that at a 30-degree heading angle, the predicted roll angle... R pre The minimum value was reached, approximately 6.96 degrees. This value is significantly lower than the original heading of 12.94 degrees and below the danger threshold of 10 degrees, placing it within a relatively safe range of alertness. Therefore, 30 degrees was selected as the optimal heading. θ pot The corresponding predicted roll angle R pot The angle is approximately 6.96 degrees. The system outputs specific risk avoidance advice on the display terminal: it recommends adjusting the course to 30 degrees, which is expected to reduce the roll angle to 6.96 degrees. After receiving this advice, the crew can slightly adjust the vessel's course 30 degrees towards the wave direction, thereby significantly reducing the vessel's roll motion and ensuring navigation and operational safety.

[0113] Reference Figure 2 , Figure 2 This is a graph illustrating the relationship between relative ship speed and roll angle according to an embodiment of this application. The graph shows that the roll angle increases slightly with increasing relative ship speed, consistent with the power function relationship between roll angle and relative ship speed in the calculation model.

[0114] Reference Figure 3 , Figure 3 This is a graph illustrating the effect of wave steepness on roll angle according to an embodiment of this application. The graph shows that the roll angle increases significantly with increasing wave steepness, consistent with the power function relationship between roll angle and wave steepness in the calculation model.

[0115] Reference Figure 4 , Figure 4This is a graph illustrating the relationship between relative beam and roll angle according to an embodiment of this application. The graph shows that the roll angle decreases as the relative beam increases, consistent with the exponential squared decay relationship between roll angle and relative beam in the calculation model.

[0116] Reference Figure 5 , Figure 5 This is a graph illustrating the relationship between the heading angle and the roll angle according to an embodiment of this application. It can be clearly seen from the graph that as the heading angle gradually increases from 30 degrees to 90 degrees (i.e., from oblique headwinds to crosswinds), the roll angle first increases and then decreases with the increase of the heading angle, reaching its maximum when the heading angle reaches 75 degrees, which is consistent with the relationship between the roll angle and the heading angle in the calculation model.

[0117] Reference Figure 6 , Figure 6 This is a scatter plot comparing the calculated roll angle with measured values ​​from actual ship and physical model tests, according to an embodiment of this application. The comparison results show that the maximum error between the calculated and experimental values ​​of this invention is within 10%, and the correlation coefficient R... 2 It can reach above 0.95.

[0118] The above description is merely a preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in this application, based on the technical solution and concept of this application, should be included within the scope of protection of this application.

Claims

1. A method for determining the roll angle of a fishing vessel navigating under wave action, characterized in that, The method includes: Obtain the vessel parameters of the target fishing vessel and the wave environment parameters of the target sea area; Dimensionless parameters are calculated based on the ship parameters and the wave environment parameters. The dimensionless parameters include relative ship speed, wave steepness, relative ship width, and heading angle in radians. Select the corresponding roll angle calculation model based on the range of lengths of the target fishing vessel; If the length of the target fishing vessel is L pp If the length of the target fishing vessel is > 25 meters, then the first roll angle calculation model is selected; if the length L of the target fishing vessel is... pp For distances ≤ 25 meters, the second roll angle calculation model is selected; both the first roll angle calculation model and the second roll angle calculation model have the following forms: ； Where R represents the roll angle, V s Let A represent the relative ship speed, λ represent the relative ship beam, and A represent the relative ship speed. i Represents the angular value θr of the heading angle in radians. ad The relevant coefficient term, α i β i γ i This represents pre-stored coefficients; For the first roll angle calculation model: A1 = 530 - 140cos(4.57θ) rad ) - 290sin(3.45θ rad ); For the second roll angle calculation model: A2 = 640 - 250cos(2.94θ) rad ) - 200sin(2.56θ rad ); Where, θ rad Indicates the heading angle in radians; The dimensionless parameters are substituted into the selected roll angle calculation model to calculate the roll angle of the target fishing vessel.

2. The method according to claim 1, characterized in that, The ship parameters include length, beam, draft, and speed; the wave environment parameters include significant wave height, mean wave period, and heading angle.

3. The method according to claim 1, characterized in that, The calculation methods for the dimensionless parameter include: relative speed Where g represents gravitational acceleration, v represents sailing speed, and d represents draft; steep waves Where L represents wavelength and H represents effective wavelength. T represents the average wave period; The relative beam λ = L / B, where B represents the molded beam; Heading angle in radians θ rad = θ×π / 180, where θ represents the heading angle.

4. The method according to claim 1, characterized in that, After calculating the roll angle, the process also includes a risk warning step: If the roll angle R is less than the safe roll angle threshold R safe If the condition is met, it is considered a safe state and a green notification is displayed. If the roll angle R is greater than or equal to the safe roll angle threshold R safe And less than the dangerous roll angle threshold R warm If the situation is as described above, it will be considered a state of alert and a yellow warning will be issued indicating the presence of turbulence. If the roll angle R is greater than or equal to the dangerous roll angle threshold R warm If the situation is deemed dangerous, a red warning for sway risk will be issued.

5. The method according to claim 4, characterized in that, When a dangerous situation is determined, heading optimization is performed. The heading optimization includes: generating a set of candidate headings within a range of ±30 degrees with a preset step size based on the current heading angle θ, calculating the predicted roll angle corresponding to each candidate heading, and recommending the heading with the smallest predicted roll angle as the optimized heading.

6. A system for determining the roll angle of a fishing vessel navigating under wave action, characterized in that, include: The parameter acquisition module is used to acquire the vessel parameters of the target fishing vessel and the wave environment parameters of the target sea area; The parameter processing module is used to calculate dimensionless parameters based on the ship parameters and the wave environment parameters. The dimensionless parameters include relative ship speed, wave steepness, relative ship width, and heading angle in radians. The model matching module is used to select the corresponding roll angle calculation model according to the length range of the target fishing vessel; The roll angle calculation module is used to substitute the dimensionless parameters into the selected roll angle calculation model to calculate the roll angle of the target fishing vessel. The model matching module further includes: if the length of the target fishing vessel is L... pp If the length of the target fishing vessel is > 25 meters, then the first roll angle calculation model is selected; if the length L of the target fishing vessel is... pp For distances ≤ 25 meters, the second roll angle calculation model is selected; both the first roll angle calculation model and the second roll angle calculation model have the following forms: ； Where R represents the roll angle, V s Let A represent the relative ship speed, λ represent the relative ship beam, and A represent the relative ship speed. i Represents the angular value θr of the heading angle in radians. ad The relevant coefficient term, α i β i γ i This represents pre-stored coefficients; For the first roll angle calculation model: A1 = 530 - 140cos(4.57θ) rad ) - 290sin(3.45θ rad ); For the second roll angle calculation model: A2 = 640 - 250cos(2.94θ) rad ) - 200sin(2.56θ rad ); Where, θ rad This indicates the heading angle in radians.

7. The system according to claim 6, characterized in that, It also includes an early warning optimization module, which compares the roll angle with a preset threshold to output the risk level, and when the state is determined to be dangerous, it generates a set of candidate headings within a preset step size within a range of ±30 degrees based on the current heading angle, calculates the predicted roll angle corresponding to each candidate heading, and recommends the heading with the smallest predicted roll angle as the optimized heading.

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