Method for long-endurance flight of bionic variant aircraft near sea surface based on dynamic gliding

Abstract

The invention discloses a bionic variant aircraft near sea surface long endurance flight method based on dynamic gliding. The method comprises the steps that a bionic variant aircraft is controlled to enter a preset gradient wind field to fly with a reference aerodynamic configuration; according to the parameters of the preset gradient wind field and the flight parameters of the bionic variant aircraft, a direct point collocation method is adopted, and an optimized flight path is obtained through calculation; controlling the bionic variant aircraft to fly in a preset gradient wind field according to the optimized flight path, sensing the change of the wind field parameters at a certain frequency, and updating the optimized flight path according to the change of the wind field parameters sensed in real time in combination with the wind field model; and controlling the bionic variant aircraft to fly in the preset gradient wind field according to the updated optimized flight path, and repeating the step of updating the optimized flight path until the flight is finished. By means of the method, the environment adaptability and the energy obtaining efficiency of the bionic variant aircraft are improved, and the cruising ability of the bionic variant aircraft in different scenes is expanded.

Description

Technical Field

[0001] The present invention belongs to the technical field of flight mechanics, and in particular relates to a method for a bionic variant aircraft to fly near the sea surface for a long time based on dynamic gliding. Background Art

[0002] Drones are widely used in various fields, often performing tasks such as tracking and search and rescue, environmental surveys, and meteorological research. Improving a drone's flight time can increase the time and coverage of its missions. Therefore, flight time is a key indicator in drone design, and long flight time is an important direction for the future development of drones.

[0003] The flight time of a drone depends on both its energy consumption rate and the amount of energy onboard. Reducing drone drag and improving engine efficiency are approaches that focus on reducing energy consumption, but these approaches are limited by the principles of physics and have limited flight time benefits. Employing new energy sources and increasing battery energy density are approaches that focus on increasing onboard energy, but these approaches are limited by the drone's payload and space requirements, and the flight time improvement has a theoretical upper limit. Therefore, only by utilizing external energy sources or supplementing onboard energy sources with external energy can the current bottlenecks in improving drone flight time be overcome. Summary of the Invention

[0004] The technology of the present invention solves the problem: overcomes the shortcomings of the existing technology, provides a long-duration flight method for a bionic variant aircraft near the sea surface based on dynamic gliding, formulates a bionic variant aircraft with a variable configuration based on the bionic mechanism of dynamic gliding of albatrosses in nature, and provides deformation strategies and flight methods in different stages of dynamic gliding, aiming to improve the environmental adaptability and energy acquisition efficiency of the bionic variant aircraft and expand its endurance in different scenarios.

[0005] In order to solve the above technical problems, the present invention discloses a method for a bionic variant aircraft to fly near the sea surface for a long time based on dynamic gliding, comprising:

[0006] Controlling the bionic variant aircraft to fly in a preset gradient wind field with a reference aerodynamic configuration;

[0007] According to the parameters of the preset gradient wind field and the flight parameters of the bionic variant aircraft, the optimized flight path is calculated using the direct point matching method.

[0008] The bionic variant aircraft is controlled to fly in a preset gradient wind field according to an optimized flight path, and changes in wind field parameters are sensed at a certain frequency. Based on the real-time changes in wind field parameters sensed, the optimized flight path is updated in combination with the wind field model to obtain an updated optimized flight path.

[0009] The bionic variant aircraft is controlled to fly in a preset gradient wind field according to the updated optimized flight path, and the step of updating the optimized flight path is repeated until the flight ends.

[0010] In the above-mentioned long-duration flight method of a bionic variant aircraft near the sea surface based on dynamic gliding, when the direct point collocation method is used to calculate the optimized flight path, the constraints are as follows: γ min ≤γ≤γ max , ψ min ≤ψ≤ψ max , V min ≤V≤V max , C Lmin ≤C L ≤C Lmax , h≥h min ; Wherein, γ represents the pitch angle of the bionic variant aircraft, ψ represents the heading angle of the bionic variant aircraft, V represents the flight speed of the bionic variant aircraft, C L represents the lift coefficient of the bionic variant aircraft, h represents the flight altitude of the bionic variant aircraft; the subscripts min and max represent the preset minimum value and the preset maximum value respectively.

[0011] In the above-mentioned method of long-duration flight of a bionic variant aircraft near the sea surface based on dynamic gliding, when the direct point matching method is used to calculate the optimized flight path, the optimization objective function F of the flight path is expressed as follows: F = minQ; where Q represents the energy consumed by the bionic variant aircraft in one dynamic gliding cycle.

[0012] In the above-mentioned method for long-duration flight of a bionic variant aircraft near the sea surface based on dynamic gliding, it is characterized in that: Among them, E(γ,ψ,V,C L ,h) represents the energy consumption rate of the bionic variant aircraft, T represents the duration of a dynamic gliding cycle, t=1,2,...,T.

[0013] In the above-mentioned method of long-duration flight of a bionic variant aircraft near the sea surface based on dynamic gliding, the wind field model is expressed as follows:

[0014]

[0015] Among them, V W (h) represents the horizontal wind speed at height h, H R Indicates the reference height, V R represents the horizontal wind speed at the reference height, and p represents the power law exponent.

[0016] In the above-mentioned method for long-duration flight of a bionic variant aircraft near the sea surface based on dynamic gliding, the bionic variant aircraft is a variable configuration aircraft, including the following configurations: climbing configuration, high-altitude turning configuration, gliding configuration and low-altitude turning configuration.

[0017] In the above-mentioned long-duration flight method of a bionic variant aircraft near the sea surface based on dynamic gliding, the optimized flight path is divided into four stages: a headwind climbing stage, a high-altitude turning stage, a downwind descent stage, and a low-altitude turning stage.

[0018] In the above-mentioned long-duration flight method of a bionic variant aircraft near the sea surface based on dynamic gliding, in the headwind climbing stage, the bionic variant aircraft flies in a climbing configuration by changing the wing configuration parameters; in the high-altitude turning stage, the bionic variant aircraft flies in a high-altitude turning configuration by changing the wing configuration parameters; in the downwind descending stage, the bionic variant aircraft flies in a gliding configuration by changing the wing configuration parameters; in the low-altitude turning stage, the bionic variant aircraft flies in a low-altitude turning configuration by changing the wing configuration parameters.

[0019] The present invention has the following advantages:

[0020] The present invention discloses a method for long-duration flight of a bionic variant aircraft near the sea surface based on dynamic gliding. By referring to the changes in the wing surface configuration of an albatross during flight, the wing surface configuration of the bionic variant aircraft is adjusted in different stages of dynamic gliding, so as to achieve targeted improvement in the energy acquisition efficiency in each stage of dynamic gliding, thereby improving the endurance. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a flow chart of a method for long-duration flight of a biomimetic variant aircraft near the sea surface based on dynamic gliding in an embodiment of the present invention;

[0022] Figure 2 This is a top view of the wing surface of a bionic variant aircraft according to an embodiment of the present invention;

[0023] Figure 3 is a schematic diagram of a typical wind field model in an embodiment of the present invention;

[0024] Figure 4 This is a schematic diagram of the dynamic gliding flight of a bionic variant aircraft according to an embodiment of the present invention;

[0025] Figure 5 This is a comparison diagram of energy changes between a fixed-configuration aircraft and a bionic variant aircraft during a dynamic gliding cycle in an embodiment of the present invention;

[0026] Figure 6 This is a schematic diagram of a flight trajectory in which the speed and direction remain unchanged before and after dynamic gliding in an embodiment of the present invention;

[0027] Figure 7 This is a schematic diagram of a flight trajectory in which the speed direction changes 180° before and after dynamic gliding in an embodiment of the present invention. DETAILED DESCRIPTION

[0028] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments disclosed in the present invention will be described in further detail below with reference to the accompanying drawings.

[0029] Wind energy, as an energy that can be directly used by drones, has great application prospects in improving flight time. The phenomenon of vertical wind speed gradients is widely present at a certain height above the sea surface and the ground. Albatrosses can use this wind gradient phenomenon to perform a dynamic gliding flight strategy of periodic upwind climbing, high-altitude turning, downwind descent, and low-altitude turning, draw energy from the wind field, and achieve non-stop flight for several months. This phenomenon can provide a reference for improving the flight time of drones. Based on this, the present invention proposes a long-duration flight method of a bionic variant aircraft near the sea surface based on dynamic gliding. Referring to the physiological mechanism of the albatross's appearance change, the present invention designs a drone (i.e., a bionic variant aircraft) that can change its appearance configuration parameters during flight. The flight method based on the dynamic gliding strategy is adopted, which effectively improves the adaptability and energy acquisition efficiency of the bionic variant aircraft in various environments and improves the flight time.

[0030] Reference Figure 1 In this embodiment, the method for long-duration flight of a bionic variant aircraft near the sea surface based on dynamic gliding includes:

[0031] Step 1: Control the bionic variant aircraft to fly in a preset gradient wind field with a reference aerodynamic configuration.

[0032] In this embodiment, the bionic morphing aircraft is a variable configuration aircraft, that is, the configuration of the bionic morphing aircraft (including climbing configuration, high-altitude turning configuration, gliding configuration and low-altitude turning configuration) can be changed by adjusting the configuration parameters. Among them, the adjustable configuration parameters include: the sweep angle χ of each section of the wing surface, the dihedral angle And the airfoil twist angle θ at the interface of each airfoil segment. Figure 2 As shown, the wing surface of the bionic variant aircraft can be divided into three sections from the inside to the outside: the inner section surface, the middle section surface and the outer section surface.

[0033] Preferably, in the reference aerodynamic configuration The main parameters and values ​​of the bionic variant aircraft are shown in Table 1 below:

[0034]

[0035] Table 1. Main parameters of bionic variant aircraft and their value examples

[0036] Furthermore, the sweep angle, dihedral angle, and airfoil twist angle of each airfoil section are all independently determined. The values ​​and variation ranges of the configuration parameters of the bionic variant aircraft are shown in Table 2 below:

[0037]

[0038] Table 2. Example of values ​​and ranges of configuration parameters of bionic variant aircraft

[0039] Step 2: Based on the parameters of the preset gradient wind field and the flight parameters of the bionic variant aircraft, the direct point matching method is used to calculate the optimized flight path.

[0040] In this embodiment, when the direct point collocation method is used to calculate the optimized flight path, the constraints are as follows: γ min ≤γ≤γ max , ψ min ≤ψ≤ψ max , V min ≤V≤V max , C Lmin ≤C L ≤C Lmax , h≥h min Among them, γ represents the pitch angle of the bionic variant aircraft, ψ represents the heading angle of the bionic variant aircraft, V represents the flight speed of the bionic variant aircraft, C L represents the lift coefficient of the bionic variant aircraft, h represents the flight altitude of the bionic variant aircraft; the subscripts min and max represent the preset minimum value and the preset maximum value respectively.

[0041] Furthermore, when the direct collocation method is used to calculate the optimized flight path, the optimization objective function F of the flight path is expressed as follows: F = minQ; Where Q represents the energy consumed by the bionic variant aircraft in a dynamic gliding cycle, E(γ,ψ,V,C L ,h) represents the energy consumption rate of the bionic variant aircraft, T represents the duration of a dynamic gliding cycle, t=1,2,...,T.

[0042] Step 3: Control the bionic variant aircraft to fly in a preset gradient wind field according to the optimized flight path, and sense the changes in wind field parameters at a certain frequency. Based on the real-time sensed changes in wind field parameters and combined with the wind field model, the optimized flight path is updated to obtain an updated optimized flight path.

[0043] In this embodiment, if Figure 3 As shown, the wind field model is expressed as follows:

[0044]

[0045] Among them, V W (h) represents the horizontal wind speed at height h, H R Indicates the reference height, V R It represents the horizontal wind speed at the reference height, p represents the power law exponent, and p at sea level is generally taken as 0.143.

[0046] Step 4: Control the bionic variant aircraft to fly in the preset gradient wind field according to the updated optimized flight path, and repeat the steps of updating the optimized flight path (refer to the updating process of step 3) until the flight ends.

[0047] In this embodiment, assuming the biomimetic morphing aircraft is flying at a certain speed at time t0, the biomimetic morphing aircraft plans an optimized flight path through a preset wind gradient, starting from its location at time t0 based on the wind field parameters sensed at time t0. At the next time, t1, the biomimetic morphing aircraft replans the optimized flight path through the preset wind gradient based on the wind field parameters sensed at time t1 and the location of the biomimetic morphing aircraft at time t1. Each time the optimized flight path is replanned, the constraints and optimization objective function listed in step 2 above are adhered to.

[0048] In this embodiment, if Figure 4 As shown in the figure, the optimized flight path is divided into four stages: headwind climbing stage, high-altitude turning stage, tailwind descent stage, and low-altitude turning stage. In the headwind climbing stage, the bionic variant aircraft's flight direction is opposite to the wind speed direction, and the bionic variant aircraft climbs at a certain climbing angle, which is manifested as an increase in altitude. When the bionic variant aircraft climbs to a certain altitude, it enters the high-altitude turning stage. In the high-altitude turning stage, the bionic variant aircraft's flight direction changes from headwind to tailwind, and then enters the tailwind descent stage. In the tailwind descent stage, the bionic variant aircraft's flight direction is the same as the wind speed direction, and the bionic variant aircraft flies at a certain descent angle, which is manifested as a decrease in altitude. After descending to a certain altitude, it enters the low-altitude turning stage. In the low-altitude turning stage, the bionic variant aircraft's flight direction changes from tailwind to headwind.

[0049] In this embodiment, during the headwind climbing stage, the bionic variant aircraft can fly in a climbing configuration by changing the wing configuration parameters, so as to achieve the effect of optimizing the climbing angle and maximizing the energy obtained in the wind field; during the high-altitude turning stage, the bionic variant aircraft can fly in a high-altitude turning configuration by changing the wing configuration parameters, so as to achieve smaller turning resistance and improve steering efficiency; during the downwind descent stage, the bionic variant aircraft can fly in a gliding configuration by changing the wing configuration parameters, so as to extend the gliding distance as much as possible; during the low-altitude turning stage, the bionic variant aircraft can fly in a low-altitude turning configuration by changing the wing configuration parameters, so as to shorten the turning time as much as possible and reduce energy consumption.

[0050] In this embodiment, due to the presence of a preset wind gradient, wind speed increases with altitude and the wind gradient decreases within a certain altitude range. When the biomimetic morphing aircraft flies against a headwind at low altitude, the headwind causes its real-time airspeed to continuously increase, leading to a continuous increase in lift. When the lift exceeds gravity, the biomimetic morphing aircraft climbs. During this climb, the biomimetic morphing aircraft utilizes the energy of the wind gradient to increase its altitude, while kinetic energy is converted into gravitational potential energy, gradually decreasing its speed. As the wind gradient intensity decreases with increasing altitude, the energy the biomimetic morphing aircraft receives from the wind field also gradually decreases. At this stage, the most important thing for the biomimetic morphing aircraft is to prolong the duration of the headwind climb phase. Therefore, compared to the baseline aerodynamic configuration, the biomimetic morphing aircraft should change its twist angle to suppress the increase in the track climb angle. Due to the stall characteristic, the biomimetic morphing aircraft does not continue to climb, but instead enters the next phase at a certain altitude. After the bionic variant aircraft climbs to a certain height, it enters the high-altitude turning stage. In this stage, the flight direction of the bionic variant aircraft changes from headwind to tailwind. This stage consumes a lot of energy, so the turning radius should be reduced as much as possible; for the bionic variant aircraft, compared with the baseline aerodynamic configuration, the twist angle of the outer wing of the bionic variant aircraft is increased to increase lift, and the sweep angle is reduced to increase lift. After completing the high-altitude turn, the biomimetic morphing aircraft enters the downwind gliding phase. The most important metric in this phase is the lift-to-drag ratio. Compared to the baseline aerodynamic configuration, the biomimetic morphing aircraft reduces its sweep angle, twist angle, and dihedral angle in this phase, maximizing its aspect ratio to improve the lift-to-drag ratio. This phase cannot continue indefinitely, primarily because as the biomimetic morphing aircraft glides downwind, its gravitational potential energy is converted into kinetic energy, increasing its speed. However, the biomimetic morphing aircraft's speed cannot continue forever. When the drag increases with speed to a certain level, the biomimetic morphing aircraft must enter the next phase. Furthermore, because the biomimetic morphing aircraft has a limited flight altitude, a minimum altitude is set to ensure safety and prevent it from touching the ground. In the final low-altitude turn phase, the biomimetic morphing aircraft performs a very rapid turn. Compared to the baseline aerodynamic configuration, the sweep angle, twist angle, and dihedral angle are increased, quickly adjusting its heading from downwind to headwind and entering the next cycle. By continuously adjusting the aerodynamic configuration parameters in each stage of dynamic gliding, the bionic variant aircraft can achieve long-term flight. Figure 5 It can be seen from the curve shown that compared with the energy change of the aircraft with fixed configuration parameters during the flight process, the bionic variant aircraft with changed configuration parameters has a smoother energy change rate, a longer cycle time, more remaining energy after the cycle ends, and a significantly improved endurance.

[0051] In this embodiment, during the dynamic gliding process, the overall heading of the bionic variant aircraft can be controlled by adjusting the angles of high-altitude steering and low-altitude steering to achieve flights in different headings to meet different mission requirements. The specific trajectory pattern is as follows: Figures 6-7 shown.

[0052] To sum up, the present invention discloses a method for long-duration flight near the sea surface of a bionic variant aircraft based on dynamic gliding. Specifically, a bionic variant aircraft with the ability to change aerodynamic configuration parameters is used to perform long-duration flight based on a dynamic gliding strategy. Within a certain altitude near the ground, a dynamic gliding flight trajectory can be optimized according to a preset gradient wind field; when flying along the dynamic gliding flight trajectory, the energy acquisition efficiency is ensured at a high level by changing the configuration parameters and rationally utilizing changes in environmental conditions, thereby achieving an improvement in endurance.

[0053] Although the present invention has been disclosed above in terms of preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solutions of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the scope of protection of the technical solutions of the present invention.

[0054] The contents not described in detail in the specification of the present invention belong to the common knowledge of professionals in this field.

Claims

1. A method for long-duration flight of a biomimetic variant aircraft near the sea surface based on dynamic gliding, characterized in that: include: Controlling the bionic variant aircraft to fly in a preset gradient wind field with a reference aerodynamic configuration; According to the parameters of the preset gradient wind field and the flight parameters of the bionic variant aircraft, the optimized flight path is calculated using the direct point matching method. The bionic variant aircraft is controlled to fly in a preset gradient wind field according to an optimized flight path, and changes in wind field parameters are sensed at a certain frequency. Based on the real-time changes in wind field parameters sensed, the optimized flight path is updated in combination with the wind field model to obtain an updated optimized flight path. The bionic variant aircraft is controlled to fly in a preset gradient wind field according to the updated optimized flight path, and the step of updating the optimized flight path is repeated until the flight ends.

2. The method for long-duration flight of a bionic deformable aircraft near the sea surface based on dynamic gliding according to claim 1, characterized in that: When the direct collocation method is used to calculate the optimized flight path, the constraints are as follows: γ min ≤γ≤γ max , ψ min ≤ψ≤ψ max , V min ≤V≤V max , C Lmin ≤C L ≤C Lmax , h≥h min ; Wherein, γ represents the pitch angle of the bionic variant aircraft, ψ represents the heading angle of the bionic variant aircraft, V represents the flight speed of the bionic variant aircraft, C L represents the lift coefficient of the bionic variant aircraft, h represents the flight altitude of the bionic variant aircraft; the subscripts min and max represent the preset minimum value and the preset maximum value respectively.

3. The method for long-duration flight of a bionic deformable aircraft near the sea surface based on dynamic gliding according to claim 2, characterized in that: When the direct point matching method is used to calculate the optimized flight path, the optimization objective function F of the flight path is expressed as follows: F=minQ; where Q represents the energy consumed by the bionic variant aircraft in one dynamic gliding cycle.

4. The method for long-duration flight of a bionic deformable aircraft near the sea surface based on dynamic gliding according to claim 3, characterized in that: Among them, E(γ,ψ,V,C L ,h) represents the energy consumption rate of the bionic variant aircraft, T represents the duration of a dynamic gliding cycle, t=1,2,...,T.

5. The method for long-duration flight of a bionic deformable aircraft near the sea surface based on dynamic gliding according to claim 4, characterized in that: The wind field model is expressed as follows: Among them, V W (h) represents the horizontal wind speed at height h, H R Indicates the reference height, V R represents the horizontal wind speed at the reference height, and p represents the power law exponent.

6. The method for long-duration flight of a bionic deformable aircraft near the sea surface based on dynamic gliding according to claim 1, characterized in that: The bionic variant aircraft is a variable configuration aircraft, including the following configurations: climbing configuration, high-altitude turning configuration, gliding configuration and low-altitude turning configuration.

7. The method for long-duration flight of a bionic deformable aircraft near the sea surface based on dynamic gliding according to claim 6, characterized in that: The optimized flight path is divided into four stages: headwind climbing stage, high-altitude turning stage, downwind descending stage and low-altitude turning stage.

8. The method for long-duration flight of a bionic deformable aircraft near the sea surface based on dynamic gliding according to claim 7, characterized in that: During the headwind climbing phase, the bionic variant aircraft flies in a climbing configuration by changing the wing configuration parameters; during the high-altitude turning phase, the bionic variant aircraft flies in a high-altitude turning configuration by changing the wing configuration parameters; during the downwind descending phase, the bionic variant aircraft flies in a gliding configuration by changing the wing configuration parameters; during the low-altitude turning phase, the bionic variant aircraft flies in a low-altitude turning configuration by changing the wing configuration parameters.

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