A method for constructing a hovercraft safety envelope

Abstract

This invention provides a method and apparatus for constructing a safety envelope for a hovercraft, relating to the field of marine technology, and particularly to a technology for assessing and controlling ship navigation safety. More specifically, this invention discloses a method for constructing a safety envelope for a hovercraft that considers multi-degree-of-freedom coupling for different sea states. The method for constructing the safety envelope of a hovercraft includes: obtaining a preset four-degree-of-freedom motion model of the hovercraft, wherein the four-degree-of-freedom motion model is used to characterize the coupling relationship of the hovercraft's sway, roll, heel, and yaw motions; for at least one preset sea state, based on the four-degree-of-freedom motion model, systematically traversing a set of coupled state parameters including longitudinal motion, lateral motion, heel motion, and rotational motion, and judging the motion stability under each parameter combination to determine a set of stable state boundaries under the sea state; and generating a multi-dimensional safety envelope that characterizes the intrinsic correlation of the multiple coupled state parameters and corresponds to the sea state based on the set of stable state boundaries. Through the above steps, this invention can comprehensively consider the high-order nonlinear strongly coupled motion characteristics of the hovercraft and external environmental interference, thereby comprehensively constructing its high-dimensional safety envelope.

Description

Technical Field

[0001] This invention relates to the field of marine technology, and more particularly to a technology for assessing and controlling ship navigation safety. More specifically, this invention discloses a method for constructing a safety envelope for hovercraft that considers multi-degree-of-freedom coupling and is applicable to different sea states. Background Technology

[0002] A hovercraft is a special type of high-performance vessel that uses a hovercraft fan to create a pressurized air cushion between the hull and the water surface to support the hull, thus significantly reducing or completely reducing its levitation during navigation. This unique navigation mechanism gives it some characteristics of both ships and aircraft, but it also results in inherent defects such as poor navigation stability and weak resistance to external interference. In actual navigation, hovercraft are prone to serious safety accidents such as drifting, tail-swinging, nose-downing, and even capsizing due to improper handling or encountering severe sea conditions. Therefore, scientifically determining the safety envelope of hovercraft and conducting safety early warning and control based on this envelope is of paramount importance for ensuring navigation safety and leveraging its high maneuverability.

[0004] In academic research and engineering practice, several methods have been developed for determining the safety envelope of ships, primarily including experimental methods, phase plane methods, elliptic domain methods, and Lyapunov function methods. However, these methods have significant limitations when applied to hovercraft. First, unlike conventional surface ships that only require a three-degree-of-freedom motion model, hovercraft's heel motion is highly coupled with its longitudinal, lateral, and yaw motions, necessitating at least a four-degree-of-freedom (pitch, sway, heel, yaw) kinematic model to accurately describe its motion characteristics. This renders the phase plane method, applicable only to third-order and lower systems, directly ineffective. Second, while experimental methods are intuitive, they suffer from high costs, long cycles, and difficulty in covering all extreme conditions. Although elliptic domain methods and Lyapunov function methods can provide safety boundaries in mathematical terms, they suffer from difficulties in constructing Lyapunov functions, computational inconvenience, and overly conservative evaluation results. This conservatism severely limits the maneuverability of hovercraft.

[0005] In addition, existing technologies have attempted to construct safety boundaries using intelligent algorithms, such as the method for determining the safety boundary of a hovercraft disclosed in patent application CN201510593660.X, which uses a BP neural network model to search and form a safety boundary. However, existing technologies have several drawbacks: First, they do not consider external wind and wave interference, while the safety boundary varies significantly under different sea states; second, the safety boundary they construct is bound to a specific automatic control law, and when the control law changes, the safety envelope also changes, failing to reflect the inherent safety characteristics of the hull itself; third, this method is not applicable to manual operation modes and actual scenarios where automatic and manual operation frequently switch. More importantly, current methods for defining safety boundaries have a common flaw: they usually determine the sideslip angle, turning rate, and heel angle independently based on speed, resulting in multiple independent two-dimensional safety boundaries such as "speed-sideslip angle," "speed-turning rate," and "speed-heel." This method ignores the inherent strong coupling between longitudinal motion, lateral motion, rotational motion, and heeling motion, resulting in a conservative assessment of the safety boundary, which fails to truly reflect the comprehensive safety status of the hovercraft in complex dynamic processes.

[0006] In summary, existing technologies lack an effective method to comprehensively and accurately construct the high-dimensional safety envelope of hovercraft by taking into account its high-order, nonlinear, and strongly coupled motion characteristics as well as external environmental interference. Summary of the Invention

[0007] This invention provides a method for constructing a safety envelope for a hovercraft, comprising the following steps: a) Obtain a preset four-degree-of-freedom motion model of the hovercraft, wherein the four-degree-of-freedom motion model is used to characterize the coupling relationship of the pitching, swaying, heeling and yaw motions of the hovercraft. b) For at least one preset sea state, based on the four-degree-of-freedom motion model, a set of stable state boundaries under the sea state is determined by systematically traversing a set of coupled state parameters including longitudinal motion, lateral motion, roll motion and rotational motion, and judging the motion stability under each parameter combination. c) Based on the set of stable state boundaries, generate a multidimensional safety envelope that can characterize the intrinsic correlation of the multiple coupled state parameters and corresponds to the sea state.

[0008] Step a) involves obtaining a preset four-degree-of-freedom motion model of the hovercraft, specifically including: establishing a set of differential equations of motion as shown in equation (I): in, The total mass of the hull; For the motion coordinate system The linear velocity component of the shaft; For the motion coordinate system Angular velocity components of the axis; These are the corresponding linear acceleration and angular acceleration, respectively. To bypass Moment of inertia of the shaft; For along The net external force on the shaft; To bypass The net external torque on the shaft. The resultant external force and resultant external torque are decomposed according to equation (II): Where F and M represent the net external force and net external torque, respectively, and the subscripts x, y, and z represent the x-axis, y-axis, and z-axis, respectively. These represent aerodynamic force, hydrodynamic force, aerodynamic momentum force, propeller force, and rudder force, respectively.

[0009] Step b) of the above steps involves determining the motion stability under each parameter combination, specifically including: 3.1 Solving for the state of the balancing actuator: Substituting the parameter combination into the four-degree-of-freedom motion model and setting the acceleration terms of all motions to 0, in order to reverse-solve for the actuator state required to maintain the stable motion state of the parameter combination; 3.2 Performing simulation: Keeping the actuator state obtained in step 3.1 unchanged, using the parameter combination as the initial condition, running the four-degree-of-freedom motion model for simulation; 3.3 Determining stability: If, during the simulation, the coupling state parameters converge and the data deviation between two consecutive simulation steps is less than a preset threshold. If the motion state under the parameter combination is determined to be stable, then the motion state is determined to be stable.

[0010] In step b), a set of coupled state parameters is systematically traversed, specifically using a nested loop traversal strategy. The loop structure, from the outside to the inside, is as follows: longitudinal velocity. External circulation, lateral speed Cycle, pitch angle Cyclic, roll rate Cycle and slew rate The innermost loop.

[0011] In step c), generating the multidimensional security envelope specifically involves: incorporating the longitudinal velocity from the coupling state parameters... lateral velocity Tilt angle and yaw rate As an index dimension, a four-dimensional gridded data structure is created, and the maximum and minimum slew rates corresponding to the set of stable state boundaries are used. Populate this data structure to generate a multidimensional lookup table.

[0012] Using the set of stable state boundaries as a training dataset, an implicit surface representing the safe envelope boundary is generated through a fitting algorithm. .

[0013] This specification also provides an embodiment for constructing a safety envelope for hovercraft, the embodiment comprising: Motion model construction module: Obtain a preset four-degree-of-freedom motion model of the hovercraft. The four-degree-of-freedom motion model is used to characterize the coupling relationship of the pitch, sway, roll and yaw motions of the hovercraft. State boundary generation module: For at least one preset sea state, based on the four-degree-of-freedom motion model, it systematically traverses a set of coupled state parameters including longitudinal motion, lateral motion, roll motion and rotation motion, and judges the motion stability under each parameter combination to determine a set of stable state boundaries under the sea state. Safety envelope generation module: Based on the set of stable state boundaries, it generates a multidimensional safety envelope that can characterize the intrinsic correlation of the multiple coupled state parameters and corresponds to the sea state.

[0014] An electronic device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the computer program, implements the aforementioned method for constructing a hovercraft safety envelope.

[0015] A computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described method for constructing a hovercraft safety envelope.

[0016] The method and apparatus for constructing a safety envelope for hovercraft disclosed in this invention fundamentally solves the core problems of existing technologies in assessing the navigation safety of hovercraft, such as strong conservatism, neglect of coupling, and detachment from actual sea conditions.

[0017] This invention achieves accurate reproduction of the key dynamic characteristics of hovercraft by constructing a four-degree-of-freedom motion model. Existing technologies often employ three-degree-of-freedom models unsuitable for hovercraft, or phase-plane methods that are unusable due to order limitations, fundamentally failing to accurately capture the motion mechanism of hovercraft. This invention recognizes that heel motion and its strong coupling with pitch, sway, and yaw motions are key intrinsic factors leading to accidents such as sideslip, tail-whipping, and even capsizing of hovercraft. Therefore, the four-degree-of-freedom model used in this invention incorporates this core physical characteristic and performs a refined decomposition of forces, constructing a high-fidelity digital twin. This provides a solid, reliable, and realistic physical model foundation for all subsequent analyses, ensuring the accuracy and reliability of the final safety envelope from the outset. In terms of analytical methodology, this invention achieves a breakthrough shift from independent two-dimensional to coupled multi-dimensional approaches, significantly reducing the conservatism of the assessment. Existing technologies generally evaluate speed, sideslip angle, and turning rate independently, forming multiple fragmented two-dimensional safety boundaries. This method completely ignores the inherent correlation between various motion states, inevitably leading to extremely conservative conclusions and severely restricting the high maneuverability of hovercraft. This invention employs a systematic nested loop traversal algorithm to perform a combined, fully coupled stability analysis on multiple state parameters, including longitudinal, lateral, heel, and turning. This means that this invention evaluates a unified, five-dimensional state space, accurately revealing the complex coupling relationships such as the maximum allowable turning rate and sideslip angle at a specific speed and heel angle. This makes the safety boundary no longer a simple, one-size-fits-all red line, but a more flexible safety surface closely related to the ship's overall motion attitude, thereby maximizing the performance potential of the hovercraft while ensuring safety. Furthermore, this invention deeply binds the safety envelope to actual sea state, achieving a shift from static isolation to dynamic adaptation. This invention uses sea state as the initial dimension for constructing the safety envelope, generating a unique and independent safety envelope for each preset sea state level. The final output is a family of safety envelopes associated with sea state levels. This enables the ship's navigation assistance systems or automatic control systems to dynamically load and switch the safety boundaries that best match the current operating conditions based on real-time perceived environmental conditions, realizing dynamic, contextualized, and intelligent safety management, and greatly improving navigation safety and environmental adaptability in complex sea states.

[0018] This invention transforms discrete simulation data into structured, directly usable engineering products. By generating multidimensional lookup tables or fitting mathematical models, this invention solves the problem of the difficulty in applying raw simulation data in real-time to shipboard systems, providing a clear technical path for the practical implementation of safety envelopes. Both the efficient lookup and interpolation of the lookup tables and the smooth, continuous expression of the fitting functions provide a readily available data foundation for developing advanced navigation safety warning systems and intelligent hazard avoidance control systems. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram illustrating the construction of the safety envelope for the hovercraft according to the present invention. Detailed Implementation

[0021] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0022] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0023] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this application, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number and aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0024] Additionally, specific details are provided in the following description to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that practice can be carried out without these specific details.

[0025] A method for constructing a safety envelope for a hovercraft includes the following steps: a) Obtain a preset four-degree-of-freedom motion model of the hovercraft, wherein the four-degree-of-freedom motion model is used to characterize the coupling relationship of the pitching, swaying, heeling and yaw motions of the hovercraft. b) For at least one preset sea state, based on the four-degree-of-freedom motion model, a set of stable state boundaries under the sea state is determined by systematically traversing a set of coupled state parameters including longitudinal motion, lateral motion, roll motion and rotational motion, and judging the motion stability under each parameter combination. c) Based on the set of stable state boundaries, generate a multidimensional safety envelope that can characterize the intrinsic correlation of the multiple coupled state parameters and corresponds to the sea state.

[0026] This embodiment details step a), which is the process of obtaining a preset four-degree-of-freedom motion model of the hovercraft. This model is the basis for constructing the subsequent high-dimensional safety envelope.

[0027] To accurately describe the motion of the hovercraft, this embodiment first defines two coordinate systems: Fixed coordinate system This coordinate system is an inertial reference frame fixed to the Earth. Origin of the coordinate system. It is usually taken at the initial position of the hovercraft's center of gravity. The plane is a static horizontal plane, in which The positive direction of the axis points to true north or the initial direction of travel. This coordinate system is used to describe the absolute position and trajectory of the hovercraft in space.

[0028] Motion coordinate system This coordinate system is fixed to the hull and moves with the hull. Origin of the coordinate system. Located at the ship's center of gravity. The axis is parallel to the longitudinal section of the hull, pointing towards the bow as positive; The axis pointing to starboard is considered positive. The axes are determined according to the right-hand rule. This coordinate system is used to describe the ship's own motion and attitude, as well as the various external forces and moments acting on the ship.

[0029] Considering the significant impact of the high coupling between the hovercraft's heel motion and other degrees of freedom on navigation safety, this invention constructs a four-degree-of-freedom motion model describing pitch, sway, heel, and yaw. In modeling, the hovercraft is treated as a rigid body whose mass and mass distribution do not change over time. Based on the Newton-Euler equations, the following set of differential equations of motion can be established: The above set of equations describes the dynamic behavior of the ship's hull in a moving coordinate system, wherein: Indicates the total mass of the hull, These represent the hull's position along the lower edge of the moving coordinate system. Axis (longitudinal) and The linear velocity component of the axis (lateral). These represent the longitudinal and lateral linear accelerations, respectively. These represent the ship's orbit around the hull in the moving coordinate system. Shaft (tilt) and Angular velocity components of the shaft (bow rocker), These represent the angular accelerations of heel and roll, respectively. Representing the ship's hull around the coordinate system of motion respectively shaft and Moment of inertia of the shaft. Representing the forces acting on the ship's center of gravity and along the motion coordinate system, respectively. shaft and The net external force on the shaft. Representing the forces acting on the ship's center of gravity and around the motion coordinate system, respectively. shaft and The net external torque on the shaft.

[0030] The net external forces and net external moments acting on a hovercraft are the result of multiple complex factors. For detailed modeling, these need to be decomposed into components with different properties. Specifically, the total forces and moments can be decomposed into the sum of aerodynamic forces, hydrodynamic forces, aerodynamic momentum forces, propeller thrust, and rudder force.

[0031] Among them, subscript Aerodynamics refers to the forces and moments generated by wind acting on the above-water parts of a ship's hull. (Subscript) Hydrodynamics refers to the forces and moments generated by water flow acting on the wetted parts of a ship's hull. (Subscript) This refers to aerodynamic force, which is the force and torque generated by changes in airflow patterns caused by components such as lifting fans and propulsion fans. (Subscript) This represents propeller force, which is the thrust and torque generated by an air-driven propeller. (Subscript) The rudder force represents the force and torque generated when the aerodynamic rudder deflects. The specific expressions for these force and torque models, namely the environmental load model and the actuator model, can be established through wind tunnel tests and theoretical calculations. Those skilled in the art can determine them based on the specific ship type parameters, and will not be elaborated here.

[0032] To link the motion state in the moving coordinate system with the position and attitude in the fixed coordinate system, the following kinematic transformation relationship needs to be established: The heel angle is defined as the angle of inclination of the hull. The angle between the plane and the vertical plane is positive when tilted to the right. The bow angle is defined as the angle of the hull. The projection of the axis onto the horizontal plane and the fixed coordinate system The included angle of the axis. These are the heel angular velocity and the heading angular velocity, respectively. This indicates the position coordinates of the ship's center of gravity in a fixed coordinate system. This represents the velocity component of the ship's center of gravity in a fixed coordinate system.

[0033] By using a set of differential equations of motion and kinematic transformation relationships, this invention constructs a four-degree-of-freedom model that can describe the coupled motions of pitching, swaying, heeling, and bow rolling of a hovercraft.

[0034] This embodiment establishes a four-degree-of-freedom model including pitch, sway, heel, and yaw. Its core advantage lies in incorporating the heel motion, which has a significant impact on safety, and its coupling relationship with other degrees of freedom into the core consideration. This reflects the risk characteristics of hovercraft due to their unique navigation mechanism, where heel can easily exacerbate sideslip and lead to capsizing. Therefore, this model fundamentally improves the realism and reliability of subsequent simulation analysis, avoiding misjudgments of safety risks caused by model simplification. Furthermore, the model does not treat forces as a general whole, but systematically decomposes them into multiple components such as aerodynamics, hydrodynamics, aerodynamic momentum, propeller thrust, and rudder force. This refined decomposition allows the model to more realistically reflect the combined effects of external environmental disturbances such as wind and waves, as well as pilot control commands (such as changing pitch and rudder input) on the ship's motion. This provides the necessary input conditions and a high-fidelity simulation environment for accurate stability assessment under different sea states and control combinations.

[0035] For at least one preset sea state, based on the four-degree-of-freedom motion model, a set of coupled state parameters including longitudinal motion, lateral motion, heeling motion and rotational motion are systematically traversed, and the motion stability under each parameter combination is judged, so as to determine the specific execution process of a set of stable state boundaries under the sea state. Through a nested systematic traversal simulation, the safety limits of the multi-dimensional coupled state of the hovercraft under specific environmental conditions are explored and determined.

[0036] Before starting the traversal, it is necessary to first define the search range of the environmental parameters and state variables.

[0037] First, the sea state and wind speed are determined. The purpose of this invention is to construct a safety envelope for different sea states; therefore, it is necessary to first correlate the sea state level with specific environmental parameters (mainly wind speed). In this embodiment, the internationally accepted Beaufort scale and sea state level correspondence are adopted. For example, to construct a safety envelope for sea state 3, the correspondence table is first consulted to determine that sea state 3 corresponds to Beaufort scale 4, and its corresponding wind speed range is... In this embodiment, the upper limit of the wind speed range can be taken, or a specific value can be selected according to actual needs as the wind speed under this sea state level. Wind angle It can be set as needed, such as to typical operating conditions like tailwind, headwind, or crosswind.

[0038] Then, the upper limit of the longitudinal velocity traversal is determined in order to determine the traversal range of the state parameters, especially the longitudinal velocity. The upper limit needs to be pre-calculated. The pre-calculation specifically involves setting the sea state to the maximum operating sea state of the hovercraft design, such as sea state 5, the wind direction to the maximum downwind, and the propulsion system, such as the propeller pitch angle, to the full-load thrust state.

[0039] Under these conditions, the four-degree-of-freedom motion model established in step a) is used for simulation. After the ship speed stabilizes, the longitudinal velocity at this point is recorded. Define it as the maximum vertical velocity during the entire traversal process. .

[0040] Next, a systematic traversal algorithm for the coupled state parameters is executed. After initialization, a systematic traversal of the coupled state parameter space can begin to search for stable boundaries. This embodiment employs a nested loop traversal strategy, with the following logical order: 2.1 Set the initial state by selecting a sea state level, such as starting from sea state 1, and setting the corresponding wind speed. The initial motion parameters of the hovercraft are all set to zero, i.e., the longitudinal velocity. lateral speed yaw angle yaw rate and slew rate .

[0041] 2.2 Perform traversal, following a nested loop structure from the innermost to the outermost loop, as follows: 2.2.1 Longitudinal velocity Outer loop: with a preset step size from Start increasing until it reaches For each fixed The value is used to execute the inner loop of 2.2.2.

[0042] 2.2.2 Lateral velocity The loop: for a fixed Values, other motion parameters The initial value is set to 0. The preset step size is used. from Initially, increase in both positive and negative directions. Until... Under these conditions, record the current time. The value is this The maximum / minimum lateral velocity boundaries are defined for each stable condition. Combine and execute the innermost loop 2.2.3.

[0043] 2.2.3 Lap Angle The loop: for a fixed Combination, will The initial value is set to 0. The preset step size is used. from Initially, increase in both positive and negative directions. Until... Under these conditions, record the current time. The value is this The maximum / minimum tilt angle boundary. For each stable... Combine and execute the innermost loop 2.2.4.

[0044] 2.2.4 Roll angular velocity The loop: for a fixed Combination, The initial value is set to 0. The preset step size is used. from Initially, increase in both positive and negative directions. Until... Under these conditions, record the current time. The value is this The maximum / minimum roll rate boundary. For each stable condition... Combine and execute the innermost loop 2.2.5.

[0045] 2.2.5 Slew rate The innermost loop: for a fixed Combining, with a preset step size from Initially, increase in both positive and negative directions. In each... Under this value, a stability check is performed. If the check first indicates instability, the previous value is considered unstable. The value is in The boundary of the steady-state slew rate. Record the maximum steady-state slew rate respectively. and minimum steady slew rate .

[0046] 2.3 Record boundary data. During the above traversal process, all identified stable boundary points... , , , All of these will be recorded. These points together constitute the set of stable state boundaries under this sea state.

[0047] 2.4 Execute the sea state cycle. After completing the traversal of all states under a sea state level, the sea state is increased by one level, for example, from sea state level 1 to sea state level 2. Then, all steps from 2.1 to 2.3 are repeated until the set maximum working sea state is reached. In each step of the above systematic traversal algorithm, it is necessary to perform a stability judgment on a specific state point.

[0048] For a given combination of states Its stability judgment method: 3.1 Solve for the state of the balancing actuator, and substitute this state combination into the system of differential equations of motion of the four-degree-of-freedom motion model established in step a). At this time, all acceleration terms of the motion ( Set the value to 0, and solve in reverse the state of the actuator required to maintain this stable motion, that is, the required propeller pitch angle and air rudder angle.

[0049] 3.2 Perform simulation, keeping the propeller pitch angle and rudder angle obtained in step 3.1 unchanged, and combine the states. As initial conditions, a four-degree-of-freedom motion model is run for a period of time for simulation.

[0050] 3.3 During the simulation, the state parameters are continuously monitored. The changes. If, after a period of simulation, these state parameters converge and remain stable, that is, the data deviation between two consecutive simulation steps is less than a preset minimum threshold. If the current state parameter diverges or fails to converge, then the current state point is considered stable. Conversely, if any state parameter diverges or fails to converge, then the state point is considered unstable.

[0051] This method achieves a high-dimensional, fully coupled assessment of the motion state of hovercraft. Existing technologies often analyze parameters such as speed, sideslip angle, and slewing rate independently, forming multiple isolated two-dimensional safety boundaries. This approach ignores the inherent strong coupling effect between different degrees of freedom, leading to overly conservative assessment results. This invention, based on a unified four-degree-of-freedom model, systematically traverses combinations of multiple state parameters, including longitudinal, lateral, heel, and slewing angles, resulting in a five-dimensional unified safety envelope. It accurately reflects, for example, the correlation between the maximum permissible slewing rate and sideslip angle at a specific heel angle, thus more realistically characterizing the comprehensive stability characteristics of the hovercraft, effectively reducing the conservatism of the assessment, and helping to fully utilize the high maneuverability of hovercraft.

[0052] This invention directly links the safety envelope to specific sea conditions, significantly improving practicality and reliability. This embodiment sets a specific sea state level before the traversal begins, ensuring that each generated safety envelope precisely corresponds to a specific environmental condition. This provides a scientific basis for the operator or automatic control system to adopt optimal maneuvering strategies under different sea conditions, significantly enhancing the navigation safety of hovercraft in complex environments. Compared to costly, time-consuming physical testing methods that struggle to cover extreme conditions, or purely theoretical analysis methods with construction difficulties and conservatism issues, this invention provides a deterministic and repeatable algorithm. Systematic traversal through computer simulation allows for safe and efficient exploration of the entire state space, including extremely dangerous conditions, yielding comprehensive and objective stability boundary data. This not only provides a reliable tool for the design and evaluation of hovercraft but also provides a data foundation for developing advanced navigation safety warning systems and intelligent hazard avoidance control systems.

[0053] In step b), for each preset sea state level, a dataset consisting of a large number of discrete stable boundary points has been obtained. Step c) transforms these discrete data points into a structured, practically applicable, multidimensional safety envelope that can intuitively represent the coupling relationship between parameters.

[0054] For a specific sea state level The output of step b) is a set of stable boundary points, denoted as Each data point in this set Both are five-dimensional vectors, and their forms are as follows: This point represents a certain four-dimensional state. The stable rotation rate that hovercraft can achieve Boundary values; or in a certain three-dimensional state The stable roll rate that can be achieved is... The boundary values, and so on. This set of data points. Defined in this sea state The boundary of the five-dimensional security region.

[0055] To facilitate use in practical ship safety systems, a set of stability boundary points is required. Generate a structured security envelope. This embodiment provides two specific methods for generation and representation: Method 1: Generate a multidimensional lookup table: 4.1.1 The state parameters used in step b) are traversed As an index dimension, create a four-dimensional gridded data structure.

[0056] 4.1.2 Set of stable boundary points The data is then populated into this four-dimensional lookup table. Each grid point in the lookup table... The corresponding value is the maximum steady-state slew rate calculated in step b) under this condition. and minimum steady slew rate For other boundaries such as Boundaries The boundaries can also be stored in a similar way.

[0057] 4.1.3 When the hovercraft is in a certain real-time state In this case, the security system can determine the security level by querying the lookup table. If the real-time state point falls exactly on a grid point in the lookup table, the corresponding security boundary value is directly retrieved for comparison. If the state point is located between grid points, a multidimensional linear interpolation method can be used to calculate the approximate security boundary of the current point based on the boundary values ​​of the surrounding grid points.

[0058] By generating a multidimensional lookup table, discrete point sets are organized into a structured, secure envelope that enables fast lookups and continuous lookups through interpolation.

[0059] Method 2: Generate a fitted model: 4.2.1 Set of stable boundary points As a training dataset, the points within the set define the boundaries of the safe zone.

[0060] 4.2.2 Fitting the boundary, for example, a function can be constructed. The goal is to ensure that all points within the safe zone satisfy the following conditions. Points outside the safe zone satisfy Thus, the boundary of the safety envelope is defined as an implicit surface. .

[0061] Models that can be used for fitting include, but are not limited to: high-order polynomial fitting, which uses regression analysis to find a polynomial function that best approximates the boundary points; support vector machines, which use classification algorithms to find the decision boundary that distinguishes between "safe" and "unsafe" categories, and this boundary is the desired safety envelope; and neural networks, which can be trained to learn the complex nonlinear relationship between state inputs and stability (safe / unsafe). This method can generate a continuous function to represent the safety envelope, facilitating theoretical analysis.

[0062] Repeat steps a) to c) for all sea state levels requiring analysis. Ultimately, the method outputs a family of safety envelopes associated with the sea state level. Its final form can be represented as a set of mappings: in, Representing the Sea state level, where N is the total number of sea states included. This is the multidimensional safety envelope represented by method 1 or method 2 above, corresponding to the sea state.

[0063] The method for generating multidimensional lookup tables or fitting mathematical models proposed in this embodiment structures and systematizes these data points. Whether it's the efficient lookup and interpolation of the lookup table or the smooth, continuous expression of the fitting function, the original data is transformed into an engineering product that can be quickly accessed, calculated, and judged, laying the foundation for the real-time application of safety envelopes. The safety envelope generated by this method preserves the inherent coupling of motion parameters to the greatest extent and presents them in a usable form. By organizing multidimensional boundary points in a unified lookup table or a single mathematical model, the inherent correlation between parameters is solidified. For example, when the safety system queries, the input is a complete state vector containing information such as velocity, roll, and roll rate, and the result is the corresponding safety boundary that takes all these factors into account. This ensures that the judgment criteria at the final application level are completely consistent with the complex physical laws revealed during simulation analysis, avoiding information dimensionality reduction and distortion. The final safety envelope family output by this method achieves dynamic adaptation in navigation safety management. The final result is not a static, unchanging envelope, but a series of envelopes corresponding one-to-one with different sea state levels. This allows the ship's driving assistance systems or automatic control systems to dynamically load and switch the safety boundaries that best match the current operating conditions based on real-time environmental information. This adaptive capability greatly improves the accuracy of safety assessments and environmental adaptability, enabling hovercraft to effectively avoid risks in changing sea conditions while avoiding the use of overly conservative "one-size-fits-all" standards.

[0064] A device for constructing a safety envelope for a hovercraft, the device comprising: Motion model construction module: Obtain a preset four-degree-of-freedom motion model of the hovercraft. The four-degree-of-freedom motion model is used to characterize the coupling relationship of the pitch, sway, roll and yaw motions of the hovercraft. State boundary generation module: For at least one preset sea state, based on the four-degree-of-freedom motion model, it systematically traverses a set of coupled state parameters including longitudinal motion, lateral motion, roll motion and rotation motion, and judges the motion stability under each parameter combination to determine a set of stable state boundaries under the sea state. Safety envelope generation module: Based on the set of stable state boundaries, it generates a multidimensional safety envelope that can characterize the intrinsic correlation of the multiple coupled state parameters and corresponds to the sea state.

[0065] An electronic device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the computer program, implements the aforementioned method for constructing a hovercraft safety envelope.

[0066] A computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described method for constructing a hovercraft safety envelope.

[0067] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, storage, databases, or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0068] In this specification, the same or similar parts between the various embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the descriptions of the embodiments described later are relatively simple, and relevant parts can be referred to the descriptions of the foregoing embodiments.

[0069] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for constructing a safety envelope for a hovercraft, characterized in that, The method includes: a) Obtain a preset four-degree-of-freedom motion model of the hovercraft, wherein the four-degree-of-freedom motion model is used to characterize the coupling relationship of the pitching, swaying, heeling and yaw motions of the hovercraft. b) For at least one preset sea state, based on the four-degree-of-freedom motion model, a set of stable state boundaries under the sea state is determined by systematically traversing a set of coupled state parameters including longitudinal motion, lateral motion, roll motion and rotational motion, and judging the motion stability under each parameter combination. c) Based on the set of stable state boundaries, generate a multidimensional safety envelope that can characterize the intrinsic correlation of the multiple coupled state parameters and corresponds to the sea state.

2. The method for constructing a safety envelope for a hovercraft according to claim 1, characterized in that, Step a) involves obtaining a preset four-degree-of-freedom motion model of the hovercraft, specifically including: establishing a set of differential equations of motion as shown in equation (I): ； in, The total mass of the hull; For the motion coordinate system The linear velocity component of the shaft; For the moving coordinate system Angular velocity components of the axis; These are the corresponding linear acceleration and angular acceleration, respectively. To bypass Moment of inertia of the shaft; For along The net external force on the shaft; To bypass The net external torque on the shaft.

3. The method for constructing a safety envelope for a hovercraft according to claim 2, characterized in that, The resultant external force and resultant external torque are decomposed according to equation (II): ； Where F and M represent the net external force and net external torque, respectively, and the subscripts x, y, and z represent the x-axis, y-axis, and z-axis, respectively. These represent aerodynamic force, hydrodynamic force, aerodynamic momentum force, propeller force, and rudder force, respectively.

4. The method for constructing a safety envelope for a hovercraft according to claim 3, characterized in that: Step b) of the above steps involves determining the motion stability under each parameter combination, specifically including: 3.1 Solving for the state of the balancing actuator: Substituting the parameter combination into the four-degree-of-freedom motion model and setting all acceleration terms of the motion to 0, in reverse solving for the actuator state required to maintain the stable motion state of the parameter combination; 3.2 Performing simulation: Keeping the actuator state obtained in step 3.1 unchanged, using the parameter combination as the initial condition, running the four-degree-of-freedom motion model for simulation; 3.3 Determining stability: If, during the simulation, the coupling state parameters converge and the data deviation between two consecutive simulation steps is less than a preset threshold. If the motion state under the parameter combination is determined to be stable, then the motion state is determined to be stable.

5. The method for constructing a safety envelope for a hovercraft according to claim 4, characterized in that: In step b), a set of coupled state parameters is systematically traversed, specifically using a nested loop traversal strategy. The loop structure, from the outside to the inside, is as follows: longitudinal velocity. External circulation, lateral speed Cycle, pitch angle Cyclic, roll rate Cycle and slew rate The innermost loop.

6. The method for constructing a safety envelope for a hovercraft according to claim 5, characterized in that: In step c), generating the multidimensional security envelope specifically involves: incorporating the longitudinal velocity from the coupling state parameters... lateral velocity Tilt angle and yaw rate As an index dimension, a four-dimensional gridded data structure is created, and the maximum and minimum slew rates corresponding to the set of stable state boundaries are used. Populate this data structure to generate a multidimensional lookup table.

7. The method for constructing a safety envelope for a hovercraft according to claim 1, characterized in that: Using the set of stable state boundaries as a training dataset, an implicit surface representing the safe envelope boundary is generated through a fitting algorithm. .

8. An apparatus for constructing a safety envelope for a hovercraft, the apparatus being used to perform a method for constructing a safety envelope for a hovercraft as described in any one of claims 1-7, characterized in that, The device includes: Motion model construction module: Obtain a preset four-degree-of-freedom motion model of the hovercraft. The four-degree-of-freedom motion model is used to characterize the coupling relationship of the pitch, sway, roll and yaw motions of the hovercraft. State boundary generation module: For at least one preset sea state, based on the four-degree-of-freedom motion model, it systematically traverses a set of coupled state parameters including longitudinal motion, lateral motion, roll motion and rotation motion, and judges the motion stability under each parameter combination to determine a set of stable state boundaries under the sea state. Safety envelope generation module: Based on the set of stable state boundaries, it generates a multidimensional safety envelope that can characterize the intrinsic correlation of the multiple coupled state parameters and corresponds to the sea state.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the computer program, implements a method for constructing a hovercraft safety envelope as described in any one of claims 1-7.

10. A computer-readable storage medium storing a computer program that, when executed by a processor, implements a method for constructing a hovercraft safety envelope as described in any one of claims 1-7.

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