A cross-medium unmanned aerial vehicle design method and device, computer equipment and medium

Abstract

The application provides a cross-medium unmanned aerial vehicle design method, device, computer equipment and medium, and belongs to the unmanned aerial vehicle design field.The method comprises the following steps: constructing the overall shape of the basic flying wing layout of the unmanned aerial vehicle; taking the maximum lift-drag ratio of the unmanned aerial vehicle in the air and the minimum drag coefficient under water as the optimization target, and setting the wing sweepback angle, wing upwash angle and wing geometric twist angle of the unmanned aerial vehicle shape as design variables; establishing a shape parameterization model, generating a plurality of sample points in the design variable space by using a Latin hypercube sampling method; performing computational fluid dynamics simulation (CFD) on each sample point to determine the corresponding lift-drag ratio and drag coefficient; constructing a Kriging surrogate model, establishing a nonlinear mapping relationship from the three design variables to the two optimization targets and performing multi-objective optimization, and selecting the final optimization scheme according to the task requirement. The energy loss and dynamic uncertainty in the cross-medium process are significantly reduced, and the operation reliability of the unmanned aerial vehicle is improved.

Description

A cross-media unmanned aerial vehicle (UAV) design method, apparatus, computer equipment, and medium Technical Field

[0001] This invention belongs to the field of unmanned aerial vehicle (UAV) design, specifically relating to a cross-media UAV design method, apparatus, computer equipment, and medium. Background Technology

[0002] With the rapid development of unmanned systems technology, mission environments have expanded from single aerial or underwater domains to complex cross-media domains. Traditional unmanned aerial vehicles (UAVs) and unmanned underwater vehicles (UUVs) have limited functions, confined to atmospheric flight or underwater navigation respectively, making them unsuitable for emerging missions requiring frequent crossing of the water-air interface, such as three-dimensional ocean monitoring, cross-domain military reconnaissance, underwater facility maintenance, and emergency rescue. Therefore, hybrid aquatic-aerial vehicles (HAAVs) that combine aerial flight and underwater operation capabilities have become a current research hotspot.

[0003] Among numerous technological approaches, the tail-seat vertical takeoff and landing (VTOL) configuration is considered one of the ideal solutions for achieving cross-medium capability due to its unique advantages. By changing the fuselage attitude and utilizing a single propulsion system, this configuration can achieve efficient vertical takeoff and landing and horizontal flight, as well as perform complex underwater navigation and surfacing / diving operations. It effectively solves the problems of structural redundancy, weight burden, and control complexity caused by multiple independent power systems, and has great potential for compact structure and high energy utilization.

[0004] However, tail-mounted cross-medium UAVs face an extremely complex multiphysics coupling environment during the transition between media, and their shape design directly determines the success or failure of their overall performance. There is a fundamental contradiction between aerodynamic and hydrodynamic requirements for shape: high-speed aerial flight requires a streamlined, low-drag shape to reduce energy consumption and increase flight time; while underwater navigation must consider the enormous pressure, drag, and stability issues caused by fluid density. Furthermore, the entry and exit process during the water-to-air transition encounters extreme conditions such as liquid surface impact, fluid entrainment, and dramatic attitude changes, posing extreme challenges to structural strength, sealing, and control stability. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a cross-media unmanned aerial vehicle (UAV) design method, apparatus, computer equipment, and medium.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A cross-media unmanned aerial vehicle (UAV) design method, the method comprising:

[0008] Constructing the basic flying wing layout and overall shape of the drone;

[0009] With the optimization goal of maximizing the lift-to-drag ratio of the UAV in the air and minimizing the drag coefficient underwater, the wing sweep angle, wing dihedral angle, and wing geometric twist angle of the UAV shape are set as design variables.

[0010] A parametric model of the shape is established using free deformation technology (FFD), and continuous control of three design variables is achieved by moving FFD control points; a number of sample points are generated in the design variable space using the Latin hypercube sampling method.

[0011] For the UAV shape corresponding to each sample point, aerodynamic and hydrodynamic computational fluid dynamics simulations (CFD) are performed to determine the lift-to-drag ratio and drag coefficient corresponding to the sample point. The performance data of all sample points are used as a training set to construct a Kriging surrogate model to establish a nonlinear mapping relationship from three design variables to two optimization objectives.

[0012] Using the design variables as optimization variables, and based on the nonlinear mapping relationship, a non-dominated sorting genetic algorithm is used for optimization. The final optimization scheme is then selected from the obtained Pareto optimal solution set according to the task requirements.

[0013] Optionally, the overall shape of the flying wing layout of the constructed drone includes:

[0014] Based on the low-drag profile of the underwater vehicle, the wing adopts a trailing edge wave-shaped profile design and moves forward to the nose section, integrating the aerodynamic characteristics of the flying wing layout. It adopts a trailing edge concave airfoil and arranges multiple sets of control surfaces on the trailing edge of the wing to obtain the initial shape. Through multiple rounds of aerodynamic and hydrodynamic performance simulation optimization, the overall shape of the basic flying wing layout that takes into account the requirements of both air flight and underwater navigation is iteratively evolved.

[0015] Optionally, the overall shape of the flying wing layout, which combines the requirements of both air flight and underwater navigation, is iteratively evolved through multiple rounds of aerodynamic and hydrodynamic performance simulation optimization.

[0016] Aerodynamic and hydrodynamic numerical simulations were performed on the initial shape. Stability defects were identified based on the simulation results. Engineering optimization was carried out by increasing the tip-to-root ratio and straightening the trailing edge profile to form a type II layout.

[0017] Based on the aforementioned two-type layout, a geometric twist angle is incorporated into the wingtip section; a V-tail wing with folding-deployment function is added to obtain the overall shape of the basic flying wing layout; the V-tail wing has three operating modes:

[0018] During aerial mode, the V-tail fin deploys;

[0019] During the water entry mode, the V-shaped tail fin folds and retracts.

[0020] In the water surface floating mode, the V-shaped tail fin deflects downward at a predetermined angle, forming a symmetrical submersible anti-roll fin structure.

[0021] Optionally, the wing airfoil is the MH-49 trailing edge concave airfoil, and the V-tail airfoil is the NACA0012 symmetrical airfoil.

[0022] Optionally, the free deformation technique FFD is based on Bernstein polynomials, whose physical space coordinates... Calculated using the following formula:

[0023] ;

[0024] The coordinates of the FFD control points. Let be the logical coordinates of any point on the target geometry. Let be the i-th l-th Bernstein basis function.

[0025] Optionally, the range of the design variable space includes:

[0026] The wing sweep angle is 5° to 40°, the wing dihedral angle is -6° to 6°, and the wing geometric twist angle is -10° to 10°.

[0027] Optionally, the non-dominated sorting genetic algorithm is the NSGA-II algorithm.

[0028] A cross-media unmanned aerial vehicle (UAV) design apparatus, the apparatus comprising:

[0029] The building block is used to construct the basic flying wing layout and overall shape of the drone.

[0030] The determination module is used to set the wing sweep angle, wing dihedral angle, and wing geometric twist angle of the UAV as design variables with the optimization objectives of maximizing the lift-to-drag ratio of the UAV in the air and minimizing the drag coefficient underwater.

[0031] The sampling module is used to establish a parametric model of the shape using the Free Deformation (FFD) technique, and to achieve continuous control of the three design variables by moving the FFD control points; it also uses the Latin hypercube sampling method to generate several sample points in the design variable space.

[0032] The simulation module is used to perform aerodynamic and hydrodynamic computational fluid dynamics (CFD) simulations on the shape of the UAV corresponding to each sample point, and to determine the lift-to-drag ratio and drag coefficient corresponding to the sample point.

[0033] The optimization module is used to construct a Kriging surrogate model using the performance data of all sample points as a training set to establish a nonlinear mapping relationship from three design variables to two optimization objectives. Using the design variables as optimization variables, and based on the nonlinear mapping relationship, a non-dominated sorting genetic algorithm is used to perform optimization and solve the problem. Finally, the optimization scheme is selected from the Pareto optimal solution set according to the task requirements.

[0034] A computer-readable storage medium storing a computer program that, when executed by a processor, implements a cross-media unmanned aerial vehicle (UAV) design method.

[0035] A computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement a cross-media unmanned aerial vehicle (UAV) design method.

[0036] The cross-medium unmanned aerial vehicle (UAV) design method provided by this invention has the following beneficial effects:

[0037] This invention provides a systematic solution for handling cross-medium situations through parametric modeling of flying wing layout and multi-objective intelligent optimization. By using FFD technology to coordinate the control of wing sweep angle, dihedral angle, and twist angle, the high lift-to-drag ratio characteristics of the aircraft in the airspace and the low drag characteristics of underwater motion can be optimized simultaneously. For example, sweep angle adjustment can effectively balance the contradiction between high-speed flight shock wave drag and underwater pressure drag. The combined strategy of Latin hypercube sampling and Kriging surrogate model significantly improves the efficiency of multi-objective optimization, greatly reducing the time required for traditional CFD simulation and enabling rapid iteration. The Pareto solution set generated by the non-dominated sorting genetic algorithm can flexibly select optimization schemes emphasizing high-speed performance or long-endurance underwater navigation according to mission requirements, improving aerodynamic performance while enhancing stability during water entry and exit. This technical framework can effectively reconcile performance conflicts in air-water dual-medium environments, significantly reduce energy loss and dynamic uncertainties in cross-medium processes, and improve the operational reliability, mission adaptability, and environmental survivability of UAVs. Attached Figure Description

[0038] To more clearly illustrate the embodiments and design schemes of the present invention, the accompanying drawings required for this embodiment will be briefly described below. The drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 is a flowchart of a tail-seat flying wing layout cross-medium unmanned aerial vehicle design method provided by the present invention according to an exemplary embodiment.

[0040] Figure 2 is a flowchart illustrating a cross-medium unmanned aerial vehicle (UAV) design method according to an exemplary embodiment of the present invention.

[0041] Figure 3 is a layout outline of an underwater vehicle according to an exemplary embodiment of the present invention.

[0042] Figure 4 is a three-view diagram of the initial external shape layout of a tail-seat flying wing cross-medium UAV provided by the present invention according to an exemplary embodiment.

[0043] Figure 5 is a three-view diagram of a tail-seat flying wing cross-medium unmanned aerial vehicle (UAV) according to an exemplary embodiment of the present invention.

[0044] Figure 6 is a three-view diagram of a tail-seat flying wing cross-medium UAV with three different layouts according to an exemplary embodiment of the present invention.

[0045] Figure 7 is a schematic diagram of the power system distribution of a tail-seat flying wing cross-medium unmanned aerial vehicle according to an exemplary embodiment of the present invention.

[0046] Figure 8 is a profile diagram of a three-airfoil according to an exemplary embodiment of the present invention.

[0047] Figure 9 shows the lift coefficient, drag coefficient, lift-to-drag ratio, and pitching moment coefficient of three airfoils provided by the present invention according to an exemplary embodiment.

[0048] Figure 10 is a schematic diagram of the FFD control block of a wing-body assembly according to an exemplary embodiment of the present invention.

[0049] Figure 11 is a schematic diagram of normalized Latin hypercube sampling in a design space according to an exemplary embodiment of the present invention.

[0050] Figure 12 is a graph showing the prediction of air lift-to-drag ratio and underwater drag using a Kriging model according to an exemplary embodiment of the present invention.

[0051] Figure 13 is a block diagram of a cross-media unmanned aerial vehicle design device provided by the present invention according to an exemplary embodiment. Detailed Implementation

[0052] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0053] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the technical solution of this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0054] Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. In the description of this invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "connected" or "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances. In the description of this invention, unless otherwise stated, "a plurality of" means two or more, which will not be elaborated further here.

[0055] This invention proposes a layout design method for a cross-medium unmanned aerial vehicle (UAV), as shown in Figure 1. Based on a tail-seat flying wing layout, it conducts systematic design research and constructs a three-level progressive design framework: shape layout, airfoil design, and a multi-objective global optimization algorithm. First, iterative design is performed based on the underwater vehicle's shape, gradually converging to a universal water-air shape layout. Second, prioritizing aerodynamic performance, an airfoil with a high lift-to-drag ratio is found that satisfies the longitudinal stability of the flying wing layout. Finally, relying on three layout parameters—sweep angle, dihedral angle, and twist angle—a hydrodynamic and aerodynamic coupled evaluation system is established to achieve the globally optimal solution for the integrated water-air layout design. This hierarchical and progressive systematic design method overcomes the limitations of traditional single-medium optimization modes, providing theoretical support and a technical path for the engineering realization of cross-medium UAVs.

[0056] The technical solutions provided by the various embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0057] First, this invention provides a cross-medium unmanned aerial vehicle (UAV) design method, as shown in Figure 2, which includes the following steps:

[0058] S101. Construct the basic flying wing layout and overall shape of the drone.

[0059] In this step, a basic shape needs to be built for subsequent optimization.

[0060] In one embodiment, the overall shape and layout design is first carried out: the initial cross-medium UAV shape and layout are determined, and the four classic layout forms, namely the normal layout, the tailless flying wing layout, the vertical take-off and landing compound wing layout and the tail-seat compound wing layout, are compared. Based on the hybrid cross-medium strategy of "splash-in water-vertical exit water", the tail-seat compound wing layout scheme is finally determined, and multiple rounds of iterative design are carried out to gradually converge to a shape and layout that is universal for both water and air.

[0061] The concept of a hybrid cross-medium strategy was first analyzed, examining two current cross-medium motion modes: vertical takeoff and landing (VTOL) entry and exit, and splash-down entry / surface glide exit. Ultimately, a hybrid cross-medium strategy of splash-down entry and vertical exit was proposed. This strategy reduces speed during the entry phase to mitigate the impact of the cross-medium entry process; during the exit phase, a bipolar propulsion system achieves power decoupling. Underwater, a high-thrust underwater thruster provides power, switching to a high-efficiency air propeller after breaking the surface to avoid gas-liquid coupling turbulence interference during the surface glide phase. Based on the requirements of the hybrid cross-medium strategy of splash-down entry and vertical exit, and the functional objectives of prioritizing aerial cruise transfer with underwater submersible missions as a secondary function, while possessing a certain degree of buoyancy stability, a systematic comparison was conducted of four typical configurations: conventional, tailless flying wing, VTOL compound, and tail-seat configuration. Their aerodynamic efficiency, hydrodynamic performance, and mode transition requirements were analyzed. Based on the requirements of the hybrid cross-medium strategy, a tail-seat compound configuration was ultimately selected as the design basis.

[0062] Among them, the conventional layout exhibits excellent pitch and yaw stability in the airspace environment, but drag increases dramatically after entering the water, and the thrust vector direction of the rigid solid limits its cross-medium transition process to a single mode of water surface gliding acceleration, which is fundamentally conflicting with the cross-medium strategy proposed in this study; the tailless flying wing layout integrates the wing and fuselage into a complete lifting surface, improving the lift-to-drag ratio by about 20%, but the lack of a vertical stabilizer results in severely insufficient yaw damping. This tail-seat flying wing layout of cross-medium UAVs often faces insufficient directional static stability and dynamic instability; the wing of the vertical take-off and landing compound wing layout adopts The high aspect ratio design maintains high cruise capability, while relying on the vertical propulsion unit to overcome the limitations of traditional layouts in water surface taxiing. However, its complex dynamic coupling mechanism and mode conversion mechanism still cannot meet the energy and control requirements of efficient cross-medium operation. The tail-seat compound wing layout has the advantages of high thrust-to-weight ratio, low viscous drag, and the ability to achieve two-stage control of "splash-in and vertical exit". It solves the problems of water entry mode conversion control and long-term water surface taxiing in cross-medium operation faced by traditional layouts. Furthermore, the vertical stabilizer enhances the yaw control robustness, ultimately achieving a breakthrough balance between structural complexity, energy efficiency and handling stability.

[0063] After determining the tail-seat flying wing layout for cross-medium UAVs, in order to resolve the contradiction between the UAV's centroid matching in the air and underwater (centroid refers to the point of application of the resultant force during flight in the water), multiple rounds of simulation optimization were conducted. The wing was moved forward to the nose position, and the trailing edge was set as a wave profile to reduce the displacement volume, thus shifting the centroid forward, as shown in Figure 3 of the underwater vehicle. Finally, a V-tail design was adopted, which has at least three operating modes: in the air mode, the V-tail is deployed to provide directional static stability for cruise flight; in the water mode, the V-tail is folded and stored to avoid the water surface impact load at the moment of entry and to increase the pitch stability upon entry by utilizing the "tail flapping effect"; in the water surface floating mode, the V-tail deflects downward at a predetermined angle along the hinge axis, forming a submersible anti-roll fin structure symmetrically distributed on both sides of the fuselage to suppress the roll-sway coupling motion in the floating state.

[0064] For example, based on the low-drag shape of an underwater vehicle, an integrated layout incorporating flying wing aerodynamic features is constructed, resulting in the initial shape shown in Figure 4. The wing extends forward to the nose section, adopting a straight leading edge and a wavy trailing edge profile design. By moving the wing forward and corrugating the trailing edge, the tail displacement volume is reduced, causing the center of buoyancy to shift forward to meet the longitudinal matching requirements between the center of buoyancy and the center of gravity. The thickness of the fuselage midsection is increased to form a spindle-shaped cross section, which acts as a vertical stabilizing surface to enhance roll and yaw static stability. A trailing edge concave airfoil is adopted, utilizing aerodynamic camber to generate a nose-down moment to enhance longitudinal static stability. Three sets of control surfaces are arranged along the trailing edge of the wing: an inner elevator (25% of span), a mid-section aileron (25% of span), and a wingtip split rudder (25% of span) to achieve three-axis control.

[0065] In addition, it is necessary to consider the lift performance requirements of tail-seat flying wing cross-medium UAVs during aerial cruise, and select a special airfoil that can meet the longitudinal stability of the flying wing layout and has a high lift-to-drag ratio. Specifically, the requirements include the following: the airfoil should have a high lift-to-drag ratio and good stall characteristics, provide sufficient lift coefficient at the predetermined cruise speed, and have pitch moment characteristics that enable the aircraft to achieve self-trimming within the flight angle of attack range.

[0066] For example, the basic layout can be based on the low-drag profile of an underwater vehicle. The wing adopts a trailing edge wave-shaped profile design and moves forward to the nose section, integrating the aerodynamic characteristics of a flying wing layout. It adopts a trailing edge concave airfoil and arranges multiple sets of control surfaces on the trailing edge of the wing to obtain the initial shape. Through multiple rounds of aerodynamic and hydrodynamic performance simulation optimization, the basic flying wing layout overall shape that takes into account the requirements of both air flight and underwater navigation is iteratively evolved.

[0067] Among them, aerodynamic and hydrodynamic numerical simulations were performed on the initial shape. Stability defects were identified and improved based on the simulation results. Engineering optimization was carried out by increasing the tip-to-root ratio and straightening the trailing edge profile to form a two-type layout. Based on the two-type layout, a geometric twist angle was implanted in the wingtip section to improve pitch trim. A V-tail with folding-deployment function was added to enhance directional stability, and it folds when entering the water to avoid impact and deflects when floating to act as a roll damper. At the same time, the fuselage shape was optimized to form the final three-type layout for both air and water use. Based on the three-type layout, the wing airfoil was selected as the MH-49 trailing edge concave airfoil, and the V-tail airfoil was selected as the NACA0012 symmetrical airfoil, resulting in the overall shape of the basic flying wing layout.

[0068] For example, aerodynamic-hydrodynamic numerical simulations were performed on the initial shape layout to identify its defects and implement improvements, resulting in a second layout, as shown in Figure 5: increasing the tip-to-root ratio, reducing the trailing edge curvature, and straightening the aileron to wingtip trailing edge profile to improve engineering applicability; numerical simulations show that this layout has problems such as pitch moment curves converging in the near-zero region, insufficient sensitivity of the entire aircraft's focal point to aerodynamic center offset, and insufficient directional stability. Based on the above-mentioned defects, systematic improvement measures were introduced to obtain a three-type layout, as shown in Figure 6. Pitch trim was reconfigured: a geometric twist angle was implanted in the wingtip section to induce early stall in the outer wing section, thereby enhancing the nose-down moment; a "beaver tail" type extended arm elevator scheme was adopted to replace the original short arm control surface, significantly improving trim capability; directional stability was enhanced: a "V" tail was added, which provides lateral stability as a static stabilizer during cruise; the split rudder and aileron were each extended to 30% span to increase the control surface area; multi-media adaptability design: a) the V-tail is equipped with a folding-deployment mechanism. The structure is designed to fold flat along the axial direction during the cross-medium water entry phase, concealing it within the wing wake region to avoid water surface impact loads and eliminate unfavorable lever arms. Simultaneously, the "tail flap effect" generates a damping torque to enhance water entry stability. During the floating phase, the V-tail is driven to deflect downwards by 55° along the hinge axis, forming a symmetrical submersible anti-roll fin structure. This increases the waterline moment of inertia to suppress the yaw-sway coupling motion. Fuselage optimization: The fuselage is lengthened along the chord direction to provide a longer pitch control lever arm. After the V-tail provides lateral stability, the fuselage section does not need to be deliberately bulged; instead, an airfoil section is used to provide lift in conjunction with the wing. Two independent propulsion systems are set up for air and underwater operation, as shown in Figure 7: In the air, two high-thrust air propellers are symmetrically arranged on the leading edge of the wing, with the thrust line passing through the center of gravity to avoid generating unfavorable torques; in the underwater operation, an underwater ducted engine is used, housing a pair of axially connected, counter-rotating underwater propellers.

[0069] The tail volume factor method was used to determine the size of the V-tail, and its horizontal and vertical projected areas were used as the calculation basis to ensure that the lateral static stability margin requirements during the cruise phase were met. Numerical verification showed that the slope of the yaw moment coefficient and the slope of the roll moment coefficient were significantly improved, confirming that the layout stability met the requirements.

[0070] Based on the above steps, a candidate airfoil set is selected: three types of airfoils with representative aerodynamic characteristics are chosen to form candidate schemes, as shown in Figure 8, including:

[0071] a. CJ-4 Integrated Airfoil: It adopts a moderately curved trailing edge design to balance lift and drag characteristics with pitch balance.

[0072] b. XM-1D high-lift airfoil: It has a compound camber mid-curve configuration, which significantly improves lift-to-drag ratio performance.

[0073] c. MH-49 strong trim airfoil: Increased trailing edge camber, optimized nose-down moment characteristics, and enhanced trim margin.

[0074] Then, aerodynamic performance comparison and evaluation were conducted. As shown in Figure 9, under the typical Reynolds number Re=548,000 condition, the aerodynamic coefficients of each candidate airfoil were compared with the angle of attack.

[0075] a. The XM-1D airfoil exhibits the highest lift coefficient and lift-to-drag ratio in the medium-high angle of attack region, but in the low angle of attack region, the leading edge thickness results in higher drag and the lowest lift-to-drag ratio.

[0076] b. The CJ-4 airfoil has balanced lift and drag characteristics, but its zero angle of attack pitching moment is insufficient, which makes trim difficult.

[0077] c. Although the MH-49 airfoil has the lowest maximum lift, it reaches the maximum lift-to-drag ratio earliest and has a better lift-to-drag ratio than the XM-1D at the cruise angle of attack. It also has the best zero angle of attack pitching moment characteristics.

[0078] Based on the above performance comparison, the MH-49 airfoil was selected as the optimal airfoil, which achieves the best balance between high lift-to-drag ratio and longitudinal trim capability, meeting the comprehensive requirements of tail-seat flying wing layout cross-medium UAV for aerodynamic efficiency and self-trimming capability.

[0079] S102. With the optimization objectives of maximizing the lift-to-drag ratio of the UAV in the air and minimizing the drag coefficient underwater, the wing sweep angle, wing dihedral angle, and wing geometric twist angle of the UAV's shape are set as design variables. A parametric model of the shape is established using free deformation technology (FFD), and continuous control of the three design variables is achieved by moving the FFD control points. Several sample points are generated in the design variable space using the Latin hypercube sampling method.

[0080] In this step, the Free-Form Deformation (FFD) parametric method is used to conduct multi-domain performance optimization for the three core geometric parameters of the wing-body combination: sweep angle, twist angle, and dihedral angle. The sweep angle ranges from 5° to 40°, the dihedral angle from -6° to 6°, and the twist angle from -10° to 10°. Initial sample points are collected within the design space comprised of these three design variables using Latin hypercube sampling.

[0081] For example, Free-Form Deformation (FFD) is used as the core method for parametric modeling of the entire aircraft's geometry. This method is characterized by constructing a parametric control volume to enclose the target geometry, and by adjusting the coordinates of control points on the control volume, achieving smooth and continuous control of the global geometric shape. Compared to traditional parametric methods, the FFD technology used in this invention has the following significant advantages:

[0082] a. Good geometric and topological consistency: Since the entire space containing the target geometry is parameterized, the resulting geometric deformation automatically remains smooth and continuous, effectively avoiding topological errors such as surface cracking or self-intersection.

[0083] b. Universality of mesh types: This method is applicable to both structured and unstructured meshes, does not depend on the parametric representation of the original geometry, and has strong versatility;

[0084] c. High variable efficiency: Only a small number of control point displacements need to be adjusted to achieve large-scale geometric deformation that meets engineering requirements, with fewer design variables and high calculation efficiency.

[0085] Specifically, this FFD method establishes a mapping relationship from the logical space to the physical space based on Bernstein polynomials. This mapping relationship is defined by the following mathematical expression:

[0086] ;

[0087] In the formula: The coordinates of the FFD control points. Let be the logical coordinates of any point on the target geometry. Let the i-th l-th Bernstein basis function be defined as:

[0088] ;

[0089] Δx is determined by the following formula:

[0090] .

[0091] It is the adjustment amount of the connection control point. A bridge to actual geometric deformation. This is achieved by changing the positions of a few control points. The displacement of all points on the entire geometric body can be calculated using the formula. This drives the shape to undergo smooth and continuous deformation.

[0092] As shown in Figure 10, the FFD control frame of the wing-body assembly has a half-span length of 0.65m, an average aerodynamic chord length of 0.158m, a half-mode reference area of ​​0.10725m2, and an aspect ratio of 8.22.

[0093] With the dual optimization objectives of maximizing the lift-to-drag ratio in the air and minimizing the underwater drag coefficient, the wing sweep angle, dihedral angle, and geometric twist angle are used as key design variables, while the center of gravity position, static stability, and structural dimensions are set as constraints. The air cruise speed is set to 40 m / s, the angle of attack to 4°, and the underwater cruise speed to 3 m / s. The sweep angle varies from 5° to 40°, the dihedral angle from -6° to 6°, and the twist angle from -10° to 10°. The Latin hypercube sampling space is shown in Figure 11. Mapping the sample points back to the design space according to the upper and lower limits of the variations yields the initial sample points used for FFD perturbation.

[0094] S103. For the shape of the UAV corresponding to each sample point, perform aerodynamic and hydrodynamic computational fluid dynamics (CFD) simulations to determine the performance data corresponding to the sample point. Use the performance data of all sample points as a training set to construct a Kriging surrogate model to establish a nonlinear mapping relationship from three design variables to two optimization objectives.

[0095] The performance data includes lift-to-drag ratio calculated by aerodynamic simulation at a predetermined cruise speed and angle of attack, and drag coefficient calculated by hydrodynamic simulation at a predetermined underwater cruise speed.

[0096] In this step, sample points are generated in the design variable space based on the Latin hypercube sampling design; high-fidelity computational fluid dynamics (CFD) simulations are performed on each sample point to obtain its accurate aerodynamic and hydrodynamic performance data; and a Kriging model is used to establish a nonlinear mapping relationship from design variables to bi-objective response values, forming a lightweight proxy model that can replace time-consuming direct CFD calculations.

[0097] For example, based on numerical simulation results from 50 sample points, the lift-to-drag ratio in air and the drag coefficient underwater were obtained, and these were used as a training set to construct a Kriging surrogate model. Analysis of the model's response characteristics revealed the nonlinear influence of various geometric parameters on the cross-medium performance, specifically as follows:

[0098] a. Twist angle dominates aerodynamic performance and reveals the contradiction between media: The air lift-to-drag ratio has a global maximum value in the twist angle range of 4° to 7°, showing a parabolic trend, indicating that this parameter significantly affects aerodynamic efficiency by regulating pressure distribution; while the underwater drag coefficient first decreases and then increases with the increase of twist angle, with the minimum point close to 0°, which is in obvious conflict with the optimal aerodynamic range, reflecting the inherent contradiction between water and air performance.

[0099] b. Swept Angle Trans-Domain Adjustment: When the dihedral angle is fixed, the sweep angle has a weak impact on performance and is considered a minor parameter; when the torsion angle is fixed, the lift-to-drag ratio in the air changes with a single peak as the sweep angle increases, while the underwater drag continues to decrease, indicating that this parameter has the potential to coordinate the performance of both media.

[0100] c. The dihedral angle exhibits a significant interactive effect: when the sweep angle is locked, the dihedral angle has a weak impact on performance; however, when the torsion angle is fixed, the dihedral angle and the sweep angle are strongly coupled – performance decreases with increasing dihedral angle at small sweep angles, while it is positively correlated at large sweep angles, reflecting the complex response mechanism of the airfoil vortex structure to geometric parameters.

[0101] The above patterns indicate that the performance conflict caused by the torsion angle needs to be addressed during the optimization process, and the interaction effect of the sweep angle and the dihedral angle should be used for coordinated adjustment to achieve efficient cross-medium shape design.

[0102] S104. Using the design variable as the optimization variable, and based on the nonlinear mapping relationship, a non-dominated sorting genetic algorithm is used to optimize the solution, and the final optimization scheme is selected from the Pareto optimal solution set according to the task requirements.

[0103] A non-dominated sorting genetic algorithm (NSGA-II) was employed, using the surrogate model as the performance evaluator, to solve the optimization problem. The algorithm converged after 100 generations of population iterations. Through selection, crossover, and mutation operations, the population was continuously evolved, ultimately outputting a Pareto optimal solution set representing the best trade-off between aerodynamic and hydrodynamic performance. Optimization results show a significant improvement in underwater drag performance, with reductions ranging from 2.4% to 12.9% compared to the basic configuration. Parameter sensitivity analysis indicates that increasing the sweep angle and decreasing the twist angle have a significant positive effect on reducing underwater drag. In contrast, the lift-to-drag ratio optimization space is limited, with a maximum increase of 6.8% (corresponding to a cruising lift-to-drag ratio of 14.2) and a minimum of -2.3%.

[0104] Finally, multi-criteria decision-making and final scheme verification were conducted. The final scheme was selected from the Pareto solution set based on the actual task preferences, as shown in Figure 12. The basic configuration design variables are a sweep angle of 34°, a twist angle of 5°, and anhedral angle of 0°; the optimized configuration design variables are a sweep angle of 29°, a twist angle of 2°, and anhedral angle of 6°.

[0105] By coordinating the adjustment of sweep angle, twist angle, and dihedral angle, aerodynamic and hydrodynamic performance were simultaneously improved. The specific optimization mechanisms are as follows: adjusting the sweep angle to 29° enhances leading-edge airflow adhesion, expands the negative pressure area and peak value on the upper surface of the wing, thereby increasing the effective lift area; setting the twist angle to 2° optimizes the spanwise angle of attack distribution, resulting in better lift-drag characteristic matching in cruise mode; adding a 6° dihedral angle effectively suppresses lateral flow and reduces wingtip vortex intensity, significantly reducing induced drag. The improvement in underwater drag performance stems from the synergistic control of the flow field structure by the above parameters: the sweep angle adjustment optimizes the overall flow field morphology and reduces the dominant component of pressure drag; the twist angle optimization reduces the upstream projected area, weakens the adverse pressure gradient, and suppresses the rise of pressure drag near the stagnation point; the dihedral angle exhibits a significant drag reduction effect under certain sweep angle conditions.

[0106] In this optimization process, the nonlinear coupling effect between the sweep angle and the twist angle breaks through the limitations of single-variable optimization, while the upper anti-angle further enhances the gain effect of other parameters by improving flow stability, ultimately achieving an overall improvement in cross-medium aerodynamic / hydraulic performance.

[0107] The above-described method provides a systematic solution for handling cross-medium situations through parametric modeling and multi-objective intelligent optimization of flying wing layout. By using FFD technology to coordinate the control of wing sweep angle, dihedral angle, and twist angle, the high lift-to-drag ratio characteristics of the aircraft in the airspace and the low drag characteristics of underwater motion can be optimized simultaneously. For example, sweep angle adjustment can effectively balance the contradiction between high-speed flight shock wave drag and underwater pressure drag. The combined strategy of Latin hypercube sampling and Kriging surrogate model significantly improves the efficiency of multi-objective optimization, greatly reducing the time required for traditional CFD simulation and enabling rapid iteration. The Pareto solution set generated by the non-dominated sorting genetic algorithm allows for flexible selection of optimization schemes emphasizing high-speed performance or long-endurance underwater operation based on mission requirements, improving aerodynamic performance while enhancing stability during water entry and exit. This technical framework not only provides quantitative basis for cross-medium aircraft design, but its surrogate model and algorithm coupling mechanism can also be extended to other multiphysics coupling scenarios.

[0108] Secondly, the present invention also provides a cross-media unmanned aerial vehicle (UAV) design device, as shown in Figure 13, comprising:

[0109] Module 201 is used to build the basic flying wing layout and overall shape of the UAV.

[0110] The determination module 202 is used to set the wing sweep angle, wing dihedral angle and wing geometric twist angle of the UAV as design variables with the optimization objectives of maximizing the lift-to-drag ratio of the UAV in the air and minimizing the drag coefficient underwater.

[0111] The sampling module 203 is used to establish a parametric model of the shape using the free deformation technique FFD, and to achieve continuous control of the three design variables by moving the FFD control points; and to generate a number of sample points in the design variable space using the Latin hypercube sampling method.

[0112] The simulation module 204 is used to perform aerodynamic and hydrodynamic computational fluid dynamics (CFD) simulations on the shape of the UAV corresponding to each sample point, and to determine the lift-to-drag ratio and drag coefficient corresponding to the sample point.

[0113] The optimization module 205 is used to construct a Kriging surrogate model using the performance data of all sample points as a training set to establish a nonlinear mapping relationship from three design variables to two optimization objectives; using the design variables as optimization variables, and based on the nonlinear mapping relationship, a non-dominated sorting genetic algorithm is used to perform optimization and solve the problem, and the final optimization scheme is selected from the obtained Pareto optimal solution set according to the task requirements.

[0114] Employing the aforementioned device, a systematic solution for handling cross-medium situations is provided through parametric modeling of flying wing layout and multi-objective intelligent optimization. By coordinating the control of wing sweep angle, dihedral angle, and twist angle using FFD technology, the high lift-to-drag ratio characteristics of the aircraft in the airspace and the low drag characteristics of underwater motion can be optimized simultaneously. For example, sweep angle adjustment can effectively balance the contradiction between high-speed flight shock wave drag and underwater pressure drag. The combined strategy of Latin hypercube sampling and Kriging surrogate models significantly improves the efficiency of multi-objective optimization, greatly reducing the time required for traditional CFD simulations and enabling rapid iteration. The Pareto solution set generated by the non-dominated sorting genetic algorithm allows for flexible selection of optimization schemes emphasizing high-speed performance or long-endurance underwater operation based on mission requirements, enhancing stability during water entry and exit while improving aerodynamic performance. This technical framework not only provides quantitative basis for cross-medium aircraft design, but its surrogate model and algorithm coupling mechanism can also be extended to other multiphysics coupling scenarios.

[0115] The present invention also provides a computer-readable storage medium storing a computer program that can be used to perform the steps of the cross-media UAV design method provided in FIG1.

[0116] This invention also provides a computer device. At the hardware level, the computer device includes a processor, an internal bus, a network interface, memory, and non-volatile memory, and may also include other hardware required for business operations. The processor reads the corresponding computer program from the non-volatile memory into the memory and then runs it to implement the steps of the cross-media UAV design method provided in Figure 1 above.

[0117] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0118] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, as well as combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in one or more blocks of the flowchart illustrations and / or one or more blocks of the block diagrams.

[0119] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means that implement the functions specified in one or more flowcharts and / or one or more block diagrams.

[0120] These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, such that the instructions, which execute on the computer or other programmable apparatus, provide steps for implementing the functions specified in one or more flowcharts and / or one or more block diagrams.

[0121] It should be noted that the specific embodiments described above enable those skilled in the art to more fully understand the present invention, but do not limit the present invention in any way. Therefore, although the present invention has been described in detail in this specification, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the present invention; and all technical solutions and improvements that do not depart from the spirit and scope of the present invention are covered within the protection scope of the patent of the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A cross-media unmanned aerial vehicle (UAV) design method, characterized in that, The method includes: constructing the basic flying wing layout of the UAV; setting the wing sweep angle, wing dihedral angle, and wing geometric twist angle as design variables with the optimization objectives of maximizing the lift-to-drag ratio of the UAV in air and minimizing the drag coefficient underwater; establishing a parametric model of the shape using free deformation technology, and achieving continuous control of the three design variables by moving the free deformation control points; generating several sample points in the design variable space using the Latin hypercube sampling method; performing aerodynamic and hydrodynamic computational fluid dynamics simulations on the UAV shape corresponding to each sample point to determine the lift-to-drag ratio and drag coefficient corresponding to the sample point; constructing a Kriging surrogate model using the performance data of all sample points as a training set to establish a nonlinear mapping relationship from the three design variables to the two optimization objectives; using the design variables as optimization variables, and based on the nonlinear mapping relationship, using a non-dominated sorting genetic algorithm for optimization, and selecting the final optimization scheme from the obtained Pareto optimal solution set according to the task requirements; the construction of the basic flying wing layout of the UAV includes: using the design variables as optimization variables, and setting the wing sweep angle, dihedral angle, and drag coefficient of the UAV shape as design variables; and setting the wing sweep angle, dihedral angle, and drag coefficient ... Based on a low-drag linear shape, the wing adopts a trailing-edge wavy profile design that is moved forward to the nose section, integrating the aerodynamic characteristics of a flying wing layout. It employs a trailing-edge concave airfoil and multiple control surfaces are arranged on the wing's trailing edge to obtain the initial shape. Through multiple rounds of aerodynamic and hydrodynamic performance simulation optimization, the overall shape of the basic flying wing layout that meets the requirements of both air and underwater navigation is iteratively evolved. The process of iteratively evolving the overall shape of the basic flying wing layout that meets the requirements of both air and underwater navigation through multiple rounds of aerodynamic and hydrodynamic performance simulation optimization includes: performing aerodynamic and hydrodynamic simulation optimization on the initial shape... Dynamic numerical simulation was used to identify stability defects based on the simulation results. Engineering optimization was carried out by increasing the tip-to-root ratio and straightening the trailing edge profile to form a dual-type layout. Based on the dual-type layout, a geometric twist angle was implanted in the wingtip section. A V-shaped tail fin with folding-deployment function was added to obtain the overall shape of the basic flying wing layout. The V-shaped tail fin has three working modes: in the air mode, the V-shaped tail fin is deployed; in the water entry mode, the V-shaped tail fin is folded and stored; and in the water surface floating mode, the V-shaped tail fin deflects downward at a predetermined angle to form a symmetrical submersible anti-roll fin structure.

2. The method according to claim 1, characterized in that, The wing airfoil is the MH-49 trailing edge concave airfoil, and the V-tail airfoil is the NACA0012 symmetrical airfoil.

3. The method according to claim 1, characterized in that, Free deformation technology is based on Bernstein polynomials, whose physical space coordinates Calculated using the following formula: ； The coordinates of the control points for free deformation technology. Let be the i-th l-th Bernstein basis function.

4. The method according to claim 1, characterized in that, The range of the design variable space includes: wing sweep angle of 5° to 40°, wing dihedral angle of -6° to 6°, and wing geometric twist angle of -10° to 10°.

5. The method according to claim 1, characterized in that, The non-dominated sorting genetic algorithm is the NSGA-II algorithm.

6. A cross-media unmanned aerial vehicle (UAV) design device, characterized in that, The device includes: a construction module for constructing the basic flying wing layout of the UAV, including: a basic layout based on the low-drag profile of an underwater vehicle, with the wing adopting a trailing edge wave-shaped profile design and moving forward to the nose section, integrating the aerodynamic characteristics of the flying wing layout, adopting a trailing edge concave airfoil, and arranging multiple sets of control surfaces on the trailing edge of the wing to obtain the initial shape; through multiple rounds of aerodynamic and hydrodynamic performance simulation optimization, iteratively evolving the basic flying wing layout overall shape that takes into account both air flight and underwater navigation requirements; the step of iteratively evolving the basic flying wing layout overall shape that takes into account both air flight and underwater navigation requirements through multiple rounds of aerodynamic and hydrodynamic performance simulation optimization... The basic flying wing layout for flight and underwater navigation requirements includes: performing aerodynamic and hydrodynamic numerical simulations on the initial shape; identifying stability defects based on the simulation results; and optimizing the design by increasing the tip-to-root ratio and straightening the trailing edge profile to form a two-type layout. Based on the two-type layout, a geometric twist angle is incorporated into the wingtip section. A V-tail with folding and unfolding functions is added to obtain the overall shape of the basic flying wing layout. The V-tail has three operating modes: in the air mode, the V-tail is unfolded; in the water entry mode, the V-tail is folded and stored; and when floating on the water surface... In floating mode, the V-tail deflects downwards by a predetermined angle, forming a symmetrical submersible anti-roll fin structure. A determination module is used to set the wing sweep angle, wing dihedral angle, and wing geometric twist angle of the UAV's shape as design variables, with the optimization objective of maximizing the lift-to-drag ratio in air and minimizing the drag coefficient underwater. A sampling module is used to establish a parametric model of the shape using free deformation technology, and to achieve continuous control of the three design variables by moving the free deformation control points. A Latin hypercube sampling method is used to generate several sample points in the design variable space. A simulation module is used to perform aerodynamic and hydrodynamic computational fluid dynamics simulations on the UAV shape corresponding to each sample point, determining the lift-to-drag ratio and drag coefficient corresponding to the sample point. An optimization module is used to construct a Kriging surrogate model using the performance data of all sample points as a training set to establish a nonlinear mapping relationship from the three design variables to the two optimization objectives. Using the design variables as optimization variables, and based on the nonlinear mapping relationship, a non-dominated sorting genetic algorithm is used for optimization, and the final optimization scheme is selected from the obtained Pareto optimal solution set according to the task requirements.

7. A computer-readable storage medium, characterized in that, The storage medium stores a computer program, which, when executed by a processor, implements the method described in any one of claims 1 to 5.

8. A computer device, characterized in that, The method includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the method described in any one of claims 1 to 5.

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