Unmanned sailboat navigation performance prediction and wing sail attack angle control method considering ocean current influence

Abstract

The application provides a kind of unmanned sailboat navigation performance prediction and wing sail attack angle control method fusing ocean current influence, and relates to unmanned sailboat navigation performance analysis technical field.First, the mechanical balance equation of unmanned sailboat is established according to the force and moment balance relationship under stable navigation state;Then solve the stable speed calculation problem of unmanned sailboat under the condition of given heading and wing sail attack angle alpha;For a given heading, the maximum steady-state sailing speed of unmanned sailboat is calculated when all wing sail attack angles alpha={1,…,90}°;Finally, the navigation performance of unmanned sailboat is analyzed, the maximum sailing speed reached by unmanned sailboat under different headings when sailing at a certain wind speed is obtained, and the corresponding best wing sail attack angle value when reaching the maximum sailing speed is obtained, and is predicted, combined with the required best wing sail attack angle value, wing sail angle control is carried out.

Description

Technical Field

[0001] This invention relates to the field of unmanned sailboat navigation performance analysis technology, and in particular to a method for predicting the navigation performance of unmanned sailboats and controlling the angle of attack of wing sails by incorporating the influence of ocean currents. Background Technology

[0002] Unmanned sailboats are a new type of long-endurance mobile observation platform for the air-sea interface. They directly convert wind energy into propulsion through sails and obtain electricity through solar panels, eliminating the need for propellers. Predicting the navigation performance of unmanned sailboats is crucial for performance evaluation and navigation control, especially wing-sail angle-of-attack control. The ocean is a complex and dynamic environment, and unmanned sailboats are affected by ocean currents in addition to wind forces. The impact of ocean currents on ship navigation performance has always been a focus of attention. For unmanned sailboats, ocean currents have a significant impact on their navigation performance. Compared to high-speed or large ships, unmanned sailboats have lower speeds, sometimes even approaching the speeds of strong currents in certain areas; therefore, the impact of ocean currents on their navigation performance cannot be ignored.

[0003] Regarding the impact of ocean currents on the navigation performance of unmanned sailboats, Santos believes that the main effect of ocean currents is on yaw, and that course control is needed to reduce the impact of ocean currents. Johannes believes that when planning the navigation path of unmanned sailboats, the effect of ocean currents should be considered in addition to wind conditions. Clement, in his research on the control system of unmanned sailboats, treats wind as white noise and the effects of ocean currents and sea conditions as noise.

[0004] One important point to note is that unmanned sailboats and traditional propeller-driven vessels differ significantly in their propulsion mechanisms. For traditional propeller-driven unmanned vessels, since the speed is controllable, ocean currents can be considered as an external disturbance. However, for unmanned sailboats, their propulsion is governed by equations of motion or dynamic equilibrium. The hydrodynamic model of the hull-water interaction must be combined with the aerodynamic and stability constraints of the sail.

[0005] When considering the impact of ocean currents on the navigation performance of unmanned sailboats, the unmanned sailboat's velocity across the water, V STW Crucially, when an unmanned sailboat is traveling at low speeds, the friction between the hull and the seawater is the main component of its drag. Furthermore, frictional drag and appendage-induced drag are directly related to the unmanned sailboat's velocity relative to the water, V. STWRelatedly, residual drag (especially wave-making drag) also varies with the water velocity, but its main mechanism of influence is through changing the Froude number, which in turn alters the wave system structure, thus affecting the magnitude of the drag coefficient. In summary, ocean currents change the relative velocity between the hull and the seawater, causing changes in drag. The impact of ocean currents on the drag of unmanned sailboats can be analyzed using the current velocity V. c and V SOG The calculation is performed by superimposing the values.

[0006] The current methods have a drawback: most existing unmanned sailboat performance prediction and wing-sail angle-of-attack control methods reference the performance prediction methods of manned sailboats. When considering the relative speed between the hull and the water, they generally assume that the unmanned sailboat is only affected by still water. This is because manned sailboats have relatively high speeds and are less affected by ocean currents, and athletes can utilize or minimize the influence of ocean currents based on their experience. However, for unmanned sailboats with lower speeds, the influence of ocean currents cannot be ignored. When navigating an unmanned sailboat, it is necessary to adjust and control the wing-sail angle of attack based on the results obtained from the unmanned sailboat performance prediction to obtain the optimal driving force. If the influence of ocean currents is not considered when conducting performance prediction, then in actual navigation at sea, the wing-sail control model based on the still water assumption is not applicable to sea areas with ocean currents. Summary of the Invention

[0007] To address the problem that existing unmanned sailboat (UAV) performance forecasting methods do not consider the influence of ocean currents, resulting in the optimal angle of attack for the wing sail not being applicable to UAVs navigating in areas with ocean currents, this invention provides a method for UAV performance forecasting and wing sail angle of attack control that integrates ocean current influences. This method incorporates ocean current information into the initial stage of UAV performance forecasting, yielding a forecast result that includes the maximum achievable speed of the UAV at different wind speeds and in different headings, as well as the optimal wing sail angle of attack corresponding to reaching the maximum speed. Based on the optimal wing sail angle of attack, the method can control the wing sail rotation when the UAV is navigating in areas with ocean currents, thereby achieving wing sail angle of attack control and improving wind energy conversion efficiency.

[0008] On the one hand, this invention provides a method for predicting the navigation performance of unmanned sailboats and controlling the angle of attack of wing sails by incorporating the influence of ocean currents, specifically including the following steps:

[0009] Step 1: Establish the mechanical equilibrium equations for the unmanned sailboat;

[0010] Specifically, this involves establishing the mechanical equilibrium equations for the unmanned sailboat based on the force and torque balance relationships under stable navigation conditions.

[0011] The equilibrium equation is specifically as follows:

[0012] ;

[0013] In the formula, F M The propulsion force provided by the wing sail, F H M is the aerodynamic lateral force generated by the wing sail. H M is the heeling moment generated by the wing sail. R R is the restoring moment generated by the hull. T(θ,λ) R represents the total drag of the unmanned sailboat. L(θ,λ) R is the horizontal component of the hydrodynamic force generated by the hull. hull Indicates the ship's resistance during navigation, R keel Indicates the buoyancy resistance of the center plate, R rudder P represents the rudder's resistance during navigation. L keel P represents the horizontal component of the hydrodynamic force on the stabilizer plate. L rudder P represents the horizontal component of the hydrodynamic force of the rudder. L hull θ represents the horizontal component of the hydrodynamic force on the hull, λ represents the heel angle of the sailboat, λ represents the drift angle of the sailboat, GZ represents the restoring arm of the sailboat, m represents the total weight of the unmanned sailboat, and g represents the acceleration due to gravity.

[0014] Step 2: Solve for the unmanned sailboat on a given heading The problem of calculating the steady speed under the condition of wing sail angle of attack α;

[0015] The objective function for the stable speed calculation problem is defined as follows:

[0016] ;

[0017] To minimize the objective function J, the steady speed is determined given the ambient wind speed, wind direction, current speed, and current direction. ;

[0018] Step 3: For a given heading Calculate the maximum steady-state speed of the unmanned sailboat at all wing sail angles of attack α = {1, ..., 90}°:

[0019] ;

[0020] Step 4: Analyze the sailing performance of the unmanned sailboat to obtain the maximum sailing speed of the unmanned sailboat under a given wind speed in different headings, as well as the corresponding optimal wing sail angle of attack value when the maximum sailing speed is reached, and make predictions. Combine the required optimal wing sail angle of attack value to control the wing sail angle.

[0021] The analysis of the navigation performance of unmanned sailboats specifically divides the impact of ocean currents on unmanned sailboats into two types: downstream navigation and upstream navigation.

[0022] The downstream navigation state includes the following two situations:

[0023] (1) When the wind speed in the navigation area is greater than or equal to the current speed, the unmanned sailboat will continuously accelerate under the action of wind and ocean current until its speed relative to the geodetic coordinate system exceeds the current speed relative to the geodetic coordinate system, generating a speed relative to the water, and entering a new equilibrium state of driving force and resistance. At this time, the speed of the unmanned sailboat is greater than the velocity component of the current speed in the unmanned sailboat's heading direction.

[0024] (2) When the wind speed in the navigation area is less than the current speed, the unmanned sailboat accelerates under the drive of the wind and the ocean current. Eventually, the force of the ocean current becomes the driving force of the unmanned sailboat. The unmanned sailboat sails with the current. At this time, the aerodynamic force on the wing sail becomes the resistance. That is, the driving force provided by the ocean current is balanced with the external resistance. At this time, the final speed of the unmanned sailboat is less than the speed component of the ocean current in the direction of the unmanned sailboat.

[0025] The reverse-current navigation state includes the following three situations:

[0026] (1) The unmanned sailboat's velocity relative to the ground is zero: the force exerted by the ocean current on the boat is equal in magnitude and opposite in direction to the driving force provided by the sail, and the unmanned sailboat is stationary relative to the Earth's coordinate system; in this state, the output velocity relative to the ground is V. SOG =0, meaning the unmanned sailboat has no velocity relative to the Earth's coordinate system;

[0027] (2) The unmanned sailboat has a forward speed: when the driving force provided by the sail is greater than the force of the ocean current, the sail propels the unmanned sailboat to sail and obtain a ground speed V. SOG ;

[0028] (3) No forward speed for unmanned sailboats: When the driving force provided by the sails is less than the force of the ocean current, the sailboat cannot move forward. In this case, the output speed relative to the ground is V. SOG There is no solution, meaning that unmanned sailboats are not allowed to reverse.

[0029] On the other hand, this application proposes a computer-readable storage medium storing executable instructions that, when executed, cause a processor to perform the aforementioned method for predicting the navigation performance of an unmanned sailboat by incorporating ocean current influences.

[0030] Thirdly, this application proposes a computer program product, including a computer program or instructions, which, when executed by a processor, implements the aforementioned method for predicting the navigation performance of unmanned sailboats by incorporating ocean current influences.

[0031] The beneficial effects of adopting the above technical solution are as follows:

[0032] This invention provides a method for predicting the navigation performance of unmanned sailboats and controlling the angle of attack of their wing sails by integrating the influence of ocean currents. The core of this invention lies in incorporating the impact of ocean currents directly into the initial mechanical equilibrium stage of predicting the navigation performance of unmanned sailboats, starting from the perspective of the unmanned sailboat's propulsion mechanism. This invention improves the performance of unmanned sailboat navigation performance prediction when considering the influence of ocean currents, especially by obtaining the optimal angle of attack value for the wing sail when considering ocean currents. It provides a new model for controlling the angle of attack of the wing sail of unmanned sailboats, with the following specific benefits:

[0033] (1) The speed obtained after incorporating the influence of ocean currents into the initial stage of navigation performance forecasting is not a direct superposition of the speed obtained based on the still water assumption and the ocean current speed;

[0034] (2) When the influence of ocean currents is incorporated into the initial stage of navigation performance forecasting, the optimal angle of attack of the wing sail differs significantly from that based on the still water assumption. Especially in the case of strong current and low wind, the difference in the angle of attack of the wing sail can reach up to 90 degrees. That is, if the optimal angle of attack of the wing sail obtained based on the still water assumption is still used for control in the strong current area, the wing sail will not only fail to generate navigation driving force, but will instead become navigation resistance.

[0035] (3) When the ocean current is wind-driven, the speed curve of the unmanned sailboat is generally deviated along the direction of the ocean current. This results in the windward dead zone of the unmanned sailboat being asymmetrical from left to right, further affecting the windward hull-changing strategy of the unmanned sailboat. Attached Figure Description

[0036] Figure 1 Flowchart of the solution for predicting the navigation performance of unmanned sailboats by incorporating the influence of ocean currents, according to an embodiment of the present invention;

[0037] Figure 2 This is the velocity polar curve of an unmanned sailboat when the true wind speed is 5 m / s, according to an embodiment of the present invention.

[0038] Where (a) - wind flows in the same direction, (b) - wind flows in opposite directions;

[0039] Figure 3 This is the optimal angle of attack curve for the wing sail of an unmanned sailboat under different wind speeds and with the wind direction in the same direction, according to an embodiment of the present invention.

[0040] Where (a) - wind speed 1 m / s, (b) - wind speed 5 m / s;

[0041] Figure 4 This is a graph showing the extreme speed curve of an unmanned sailboat under the influence of ocean currents generated by sea breeze, according to an embodiment of the present invention. Detailed Implementation

[0042] The specific implementation methods of this application will be further described in detail below with reference to the accompanying drawings and embodiments.

[0043] Example 1:

[0044] On the one hand, this invention provides a method for predicting the navigation performance of unmanned sailboats and controlling the angle of attack of wing sails by incorporating the influence of ocean currents, specifically including the following steps:

[0045] Step 1: Establish the mechanical equilibrium equations for the unmanned sailboat;

[0046] Specifically, the unmanned sailboat is regarded as a rigid body that can sway, tilt, and roll, and the mechanical equilibrium equation of the unmanned sailboat is established based on the force and torque balance relationship under stable sailing conditions.

[0047] The equilibrium equation is specifically as follows:

[0048] ;

[0049] In the formula, F M The propulsion force provided by the wing sail, F H M is the aerodynamic lateral force generated by the wing sail. H M is the heeling moment generated by the wing sail. R R is the restoring moment generated by the hull. T(θ,λ) R represents the total drag of the unmanned sailboat. L(θ,λ) R is the horizontal component of the hydrodynamic force generated by the hull. hull Indicates the ship's resistance during navigation, R keel Indicates the buoyancy resistance of the center plate, R rudder P represents the rudder's resistance during navigation. L keel P represents the horizontal component of the hydrodynamic force on the stabilizer plate. L rudder P represents the horizontal component of the hydrodynamic force of the rudder. L hull θ represents the horizontal component of the hydrodynamic force on the hull, λ represents the heel angle of the sailboat, λ represents the drift angle of the sailboat, GZ represents the restoring arm of the sailboat, m represents the total weight of the unmanned sailboat, and g represents the acceleration due to gravity.

[0050] First, the propulsion force F provided by the wing sail. M The total sailing resistance R of the unmanned sailboat T(θ,λ) The two factors are: firstly, the state of equilibrium; and secondly, the aerodynamic lateral force F generated by the wing sail. H The horizontal component of the hydrodynamic force R generated by the hull L(θ,λ) The magnitudes are equal, but the directions are opposite; thirdly, the lateral tilting moment M generated by the wing sail H The restoring moment M generated by the hull R The ship is in equilibrium. Fluid dynamics software can be used to calculate the aerodynamic coefficients of the sail at different angles of attack and the corresponding drag of the hull at different speeds.

[0051] The above equilibrium equations can be solved in several ways. The most direct approach is to transform the solution into a constrained optimization problem: finding the maximum speed achievable by the unmanned sailboat while satisfying the equilibrium conditions described above. The solution process is as follows: Figure 1 As shown.

[0052] Step 2: Solve for the unmanned sailboat on a given heading The problem of calculating the steady speed under the condition of wing sail angle of attack α;

[0053] The objective function for the stable speed calculation problem is defined as follows:

[0054] ;

[0055] To minimize the objective function J, the steady speed is determined given the ambient wind speed, wind direction, current speed, and current direction. ;

[0056] In this embodiment, the solution is performed in a Python environment using the scipy.optimize.minimize function of the SciPy library, as follows:

[0057] given V T β T V C β C and α;

[0058] minJ(•);

[0059] Where V T β T V C β C These are the given environmental wind speed, wind direction, current velocity, and current direction, respectively.

[0060] Step 3: For a given heading Calculate the maximum steady-state speed of the unmanned sailboat at all wing sail angles of attack α = {1, ..., 90}°:

[0061] ;

[0062] Assuming the leading edge of the wingsail is always close to the visible wind, the wingsail angle of attack α ranges from 0 to 90°. The unmanned sailboat's velocity relative to the water is V. STW A value ≥0 indicates that even when affected by ocean currents, the unmanned sailboat's velocity relative to the water will not be less than zero, meaning it will not reverse under the influence of currents. Solving the equations yields the maximum speed of the unmanned sailboat in all directions.

[0063] Step 4: Analyze the sailing performance of the unmanned sailboat to obtain the maximum sailing speed of the unmanned sailboat under a given wind speed in different headings, as well as the corresponding optimal wing sail angle of attack value when the maximum sailing speed is reached, and make predictions. Combine the required optimal wing sail angle of attack value to control the wing sail angle.

[0064] The analysis of the navigation performance of unmanned sailboats specifically divides the impact of ocean currents on unmanned sailboats into two types: downstream navigation and upstream navigation.

[0065] The downstream navigation state includes the following two situations:

[0066] (1) When the wind speed in the navigation area is greater than or equal to the current speed, the unmanned sailboat will continuously accelerate under the action of wind and ocean current until its speed relative to the geodetic coordinate system exceeds the current speed relative to the geodetic coordinate system, generating a speed relative to the water, and entering a new equilibrium state of driving force and resistance. At this time, the speed of the unmanned sailboat is greater than the velocity component of the current speed in the unmanned sailboat's heading direction.

[0067] (2) When the wind speed in the navigation area is less than the current speed, the unmanned sailboat accelerates under the drive of the wind and the ocean current. Eventually, the force of the ocean current becomes the driving force of the unmanned sailboat. The unmanned sailboat sails with the current. At this time, the aerodynamic force on the wing sail becomes the resistance. That is, the driving force provided by the ocean current is balanced with the external resistance. At this time, the final speed of the unmanned sailboat is less than the speed component of the ocean current in the direction of the unmanned sailboat.

[0068] The reverse-current navigation state includes the following three situations:

[0069] (1) The unmanned sailboat's velocity relative to the ground is zero: the force exerted by the ocean current on the boat is equal in magnitude and opposite in direction to the driving force provided by the sail, and the unmanned sailboat is stationary relative to the Earth's coordinate system; in this state, the output velocity relative to the ground is V. SOG =0, meaning the unmanned sailboat has no velocity relative to the Earth's coordinate system;

[0070] (2) The unmanned sailboat has a forward speed: when the driving force provided by the sail is greater than the force of the ocean current, the sail propels the unmanned sailboat to sail and obtain a ground speed V. SOG ;

[0071] (3) No forward speed for unmanned sailboats: When the driving force provided by the sails is less than the force of the ocean current, the sailboat cannot move forward. In this case, the output speed relative to the ground is V. SOG There is no solution, meaning that unmanned sailboats are not allowed to reverse.

[0072] To analyze the impact of wind and ocean currents on the navigation performance of unmanned sailboats, we first consider two extreme states: wind and current in the same direction and wind and current in opposite directions. Under these navigation states, the unmanned sailboats will face two situations: sailing against the current and sailing with the current.

[0073] In the states of airflow in the same direction and airflow in opposite directions, Figure 2 The solid lines represent the velocity extreme curves calculated by the unmanned sailboat navigation performance prediction model based on this scheme, which includes the influence of ocean currents. The dashed lines represent the velocity extreme curves calculated without considering the influence of ocean currents (based on the still water assumption), and with the influence of ocean currents superimposed on the velocity extreme curves based on the unmanned sailboat's navigation in still water. Figure 2 As can be seen, the dashed and solid lines do not coincide, verifying the viewpoint proposed in this invention: for unmanned sailboats, the influence of ocean currents cannot be considered as a simple superposition of the unmanned sailboat's motion in still water and the ocean current; moreover, as the ocean current velocity increases, the velocity deviation obtained by the two calculation methods gradually increases on the same course. Figure 2 As shown in (a), when the wind direction is the same, the maximum speed obtained based on the velocity superposition method is higher than the speed calculated based on the method proposed in this invention. Figure 2 As shown in (b), when the wind flow is reversed, the maximum speed obtained based on the velocity superposition method is lower than the speed calculated based on the method proposed in this invention.

[0074] Depend on Figure 3 It can be seen that, when the heading angle is constant, the optimal angle of attack of the unmanned sailboat's wingsail decreases with increasing current speed, especially noticeable in low wind conditions. When the current speed is less than the wind speed, the change in the wingsail's control angle tends to be consistent with increasing wind speed, i.e., the increase in the difference between wind and current speeds. This is because when the wind speed is high, the change in apparent wind direction caused by changes in boat speed due to the current is relatively small. Figure 3 As shown in (a), when the ocean current velocity V C When the angle of attack is 2-3 kN, the wing sail is in a low angle of attack upwind sailing state under downwind and downwind conditions. When the heading angle is 180 degrees, the wing sail angle of attack is 0 degrees. This indicates that in strong current areas, when the current speed is greater than the wind speed, it will have a significant impact on the wing sail control strategy.

[0075] Example 2:

[0076] The wind direction in Example 1 and the wind direction in opposite directions represent two extreme environmental conditions selected for illustrative purposes. In most scenarios, unmanned sailboats encounter situations where the true wind direction and the ocean current direction form a certain angle. To further illustrate this more realistically, we will use the wind-driven ocean currents encountered while sailing on the open ocean as an example.

[0077] Wind speed and direction remain relatively stable over the ocean. When an unmanned sailboat navigates the ocean, ocean currents are primarily formed by the drag effect of the wind. Surface currents are approximately at a 45-degree angle to the wind direction. They deflect to the right in the Northern Hemisphere and to the left in the Southern Hemisphere, and this deflection does not change with wind speed, current speed, or latitude. Assuming the sailboat is sailing in the Northern Hemisphere with a due north wind, the current direction is approximately 225 degrees. The velocity of the ocean current driven by the wind can be calculated using the following formula:

[0078] ;

[0079] In the formula V C It is the ocean surface current velocity (m / s), V T This is the true wind speed (m / s). It is latitude;

[0080] The analysis assumes true wind speeds of 6 m / s and 9 m / s, with the unmanned sailboat navigating in the sea area at 10 degrees North latitude. Based on the above formula, the ocean current velocities are set to 0.36 kN and 0.53 kN, respectively. To enhance the comparison, a control group with a current velocity of 0 kN is added, resulting in the velocity extreme curves of the unmanned sailboat under the influence of wind-driven currents, as shown below. Figure 4 As shown. By Figure 4 It can be seen that, under the influence of ocean currents, the velocity extreme curve of the unmanned sailboat is generally shifted along the direction of the current. That is, the speed decreases in the direction against the current and increases in the direction with the current. When the heading is 135 degrees and 315 degrees, the ocean current has no effect on the speed of the unmanned sailboat. This is because when sailing in these directions, the heading is perpendicular to the direction of the ocean current, and the velocity component of the ocean current in the heading direction of the unmanned sailboat is zero. The straight line formed by connecting the two points at 135 degrees and 315 degrees divides the velocity extreme curve of the unmanned sailboat into two regions. In the right region, the ocean current does negative work, reducing the speed of the unmanned sailboat. In the left region, the ocean current does positive work, increasing the speed of the unmanned sailboat.

[0081] Example 3:

[0082] This embodiment proposes a computer-readable storage medium that stores executable instructions. When these instructions are executed, if they are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium.

[0083] The computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method for predicting the navigation performance of an unmanned sailboat that integrates the influence of ocean currents and controlling the angle of attack of the wing sail as described in the various embodiments of this application.

[0084] The aforementioned storage media include: flash memory, hard disk, multimedia card, card-type memory (e.g., SD (Secure Digital Memory Card) or DX (Memory Data Register, MDR) memory, random access memory (RAM), static random access memory (SRAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), programmable read-only memory (PROM), magnetic memory, disk, optical disk, server, APP (Application) application store, and other media capable of storing program verification codes. These media store computer programs, and when executed by a processor, they can implement the various steps of the aforementioned method for predicting the navigation performance of an unmanned sailboat by incorporating ocean current influences and controlling the angle of attack of the wing sail.

[0085] Example 4:

[0086] This embodiment proposes a computer program product, including a computer program or instructions, which, when executed by a processor, implements the aforementioned method for predicting the navigation performance of an unmanned sailboat and controlling the angle of attack of its wing sail by incorporating the influence of ocean currents.

[0087] Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or part of the technical solution, can be embodied in the form of a computer program product.

[0088] The various embodiments in this application are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0089] The scope of protection of this application is not limited to the embodiments described above. Obviously, those skilled in the art can make various modifications and variations to this disclosure without departing from the scope and spirit of this disclosure. If such modifications and variations fall within the scope of the methods disclosed herein and their equivalents, then the intent of this disclosure also includes such modifications and variations.

Claims

1. A method for predicting the navigation performance of an unmanned sailboat and controlling the angle of attack of its wing sail by integrating the influence of ocean currents, characterized in that, Includes the following steps: Step 1: Establish the mechanical equilibrium equations for the unmanned sailboat; Specifically, this involves establishing the mechanical equilibrium equations for the unmanned sailboat based on the force and torque balance relationships under stable navigation conditions. The specific mechanical equilibrium equation is as follows: ； In the formula, F M The propulsion force provided by the wing sail F H The aerodynamic lateral force generated by the wing sail M H The heeling moment generated by the wing sail M R The restoring moment generated by the hull, R T(θ,λ) The total sailing resistance of the unmanned sailboat. R L(θ,λ) The horizontal component of the hydrodynamic force generated by the hull, R hull Indicates the ship's resistance to navigation, R keel Indicates the resistance of the center plate during navigation. R rudder Indicates the rudder's resistance during navigation. P L keel This represents the horizontal component of the hydrodynamic force on the stabilizer plate. P L rudder This indicates the horizontal component of the hydrodynamic force on the rudder. P L hull This represents the horizontal component of the hydrodynamic force on the ship's hull. θ Indicates the heel angle of a sailboat, λ GZ represents the sailboat's drift angle and the sailboat's restoring arm. m Indicates the total weight of the unmanned sailboat, g Represents gravitational acceleration; Step 2: Solve for the unmanned sailboat on a given heading φ With wing sail angle of attack α The problem of calculating stable speed under certain conditions; The objective function for the steady speed calculation problem is defined as follows: ； To minimize the objective function J, the steady speed is determined given the ambient wind speed, wind direction, current speed, and current direction. ; Step 3: For a given heading φ Calculate the maximum steady-state speed of the unmanned sailboat when all wing sail angles of attack α = {1, ..., 90}°; Step 4: Analyze the sailing performance of the unmanned sailboat to obtain the maximum sailing speed reached by the unmanned sailboat under a given wind speed in different headings, as well as the corresponding optimal wing sail angle of attack value when the maximum sailing speed is reached, and make predictions. Combine the required optimal wing sail angle of attack value to control the wing sail angle.

2. The method for predicting the navigation performance of an unmanned sailboat and controlling the angle of attack of its wing sail, as described in claim 1, is characterized in that... The maximum steady-state sailing speed mentioned in step 3 is as follows: 。 3. The method for predicting the navigation performance of an unmanned sailboat and controlling the angle of attack of its wing sail, as described in claim 2, is characterized in that... Step 4 describes the analysis of the unmanned sailboat's navigation performance, specifically dividing the impact of ocean currents on the unmanned sailboat into two types: downstream navigation and upstream navigation. The downstream navigation state includes the following two situations: (1) When the wind speed in the navigation area is greater than or equal to the current speed, the unmanned sailboat will accelerate continuously under the action of wind and ocean current until the speed relative to the earth coordinate system exceeds the current speed relative to the earth coordinate system, generating a speed relative to the water, and entering a new balance state of driving force and resistance. At this time, the speed of the unmanned sailboat is greater than the velocity component of the current speed in the direction of the unmanned sailboat. (2) When the wind speed in the navigation area is less than the current speed, the unmanned sailboat accelerates under the drive of the wind and the ocean current. Eventually, the force of the ocean current becomes the driving force of the unmanned sailboat. The unmanned sailboat sails with the current. At this time, the aerodynamic force on the wing sail becomes the resistance. That is, the driving force provided by the ocean current is balanced with the external resistance. At this time, the final speed of the unmanned sailboat is less than the speed component of the ocean current in the direction of the unmanned sailboat. The reverse-current navigation state includes the following three situations: (1) The unmanned sailboat's velocity relative to the ground is zero: the force exerted by the ocean current on the boat is equal in magnitude and opposite in direction to the driving force provided by the sail, and the unmanned sailboat is stationary relative to the Earth's coordinate system; in this state, the output velocity relative to the ground is zero. V SOG =0, meaning the unmanned sailboat has no velocity relative to the Earth's coordinate system; (2) Unmanned sailboats have forward speed: When the driving force provided by the sail is greater than the force of the ocean current, the sail propels the unmanned sailboat and obtains ground speed. V SOG ; (3) No forward speed for unmanned sailboats: When the driving force provided by the sails is less than the force of the ocean current, the sailboat cannot move forward. In this case, the output speed relative to the ground is zero. V SOG There is no solution, meaning that unmanned sailboats are not allowed to reverse.

4. A computer-readable storage medium storing executable instructions, characterized in that, When the instruction is executed, the processor performs the unmanned sailboat navigation performance prediction and wing sail angle of attack control method according to any one of claims 1-3, which incorporates the influence of ocean currents.

5. A computer program product, comprising a computer program or instructions, characterized in that, When the computer program or instructions are executed by the processor, they implement the unmanned sailboat navigation performance prediction and wing sail angle of attack control method according to any one of claims 1-3, which incorporates the influence of ocean currents.

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