An energy-optimal aircraft static gliding whole-process flight trajectory planning method

Abstract

The present application relates to the technical field of trajectory planning, and particularly relates to an energy-optimized aircraft static gliding whole-process flight trajectory planning method, comprising: obtaining a vertical ascending wind speed under a hovering radius of any flight height; constructing a flight performance model of aircraft unpowered gliding performance considering hovering maneuver; obtaining a net energy gain power of the aircraft; obtaining optimal roll angles and optimal hovering airspeeds corresponding to optimal hovering radii of the aircraft at different flight heights; obtaining a flight trajectory in ascending airflow; and obtaining a whole-process flight trajectory. The present application solves how to safely complete flight in an actual task of a real flight scene of an unmanned aerial vehicle, and simultaneously accurately completes a whole-process trajectory planning of "approach-hovering energy gain-departure" with low consumption through deep integration of an integrated planning framework of multiple engineering and safety constraints, so as to provide a complete, safe, efficient and executable solution of static gliding energy gain of an unmanned aerial vehicle.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of trajectory planning, in particular to an energy-optimized aircraft static gliding whole-process flight trajectory planning method. BACKGROUND

[0002] Under the macro background of the rapid development of low-altitude economy, unmanned aerial vehicles (UAVs) as key intelligent nodes in the air are increasingly applied in the fields of regional inspection, emergency communication, environmental monitoring, and regional patrol. The common feature of these tasks is that they put forward very high requirements on the long-endurance operation capability of UAVs. At present, most small and medium-sized UAVs rely on on-board batteries or fuel as the main energy source, and their endurance is limited by the physical bottlenecks of battery energy density, fuel energy density, and platform carrying capacity, which makes it difficult to meet the demand for continuous tasks lasting for several hours or even tens of hours. Under this background, real-time energy acquisition from the flight environment has become a core technical approach to breaking through the endurance bottleneck of UAVs and achieving a leap in task capability.

[0003] Wind energy, as the most widely distributed natural resource in the atmospheric environment, provides an ideal energy source for UAVs. According to the different forms and utilization methods of wind field energy, there are mainly two technical routes: “dynamic gliding flight” using the horizontal gradient of wind speed and “static gliding flight” using vertical updraft. Updraft exists widely on the earth, and it is the type of wind field that can be skillfully utilized by human pilots so far. Through theoretical calculation, a UAV that can originally fly for 2 hours can achieve a maximum flight time of 14 hours in good weather by using updraft, so there is great potential for this type of wind field to be utilized by UAVs.

[0004] The inspiration of static soaring comes directly from the soaring behavior of large birds such as eagles and vultures in nature, as well as from unpowered gliders. The core energy source of this kind of flight is the updraft. The updraft is mainly generated by two aspects: the vertical convection caused by temperature difference or air pressure difference; the airflow uplift on the windward side caused by the slope of obstacles such as mountains and waves. The updraft is the upward flow of gas clusters, which can be small or large in volume. The cause of this phenomenon is generally due to topography and geothermal. The updraft generated by topography is called topographic updraft, such as the airflow blowing over a mountain peak, which blows up the mountain slope because of the shape of the slope. The updraft generated by geothermal is converted into a hot updraft. In general, the ground absorbs heat and heats the low-altitude airflow, forming a thermal gradient. The low-altitude airflow has a high temperature and a small density, and the high-altitude airflow has a large density, thus generating a pressure difference, thereby generating an updraft. Among them, the thermal updraft caused by uneven solar radiation on the ground is the most common and main form in the air above the land. Its physical form is usually a vertical, rotating column of warm air, with the strongest upward velocity in the core area and gradually weakening towards the periphery.

[0005] The basic principle of static soaring is that the UAV continuously circles in the core area of the updraft, skillfully using the vertical uplift of the updraft to offset or even exceed its own gravity and air resistance. In this process, the vertical kinetic energy of the updraft is efficiently converted into the gravitational potential energy of the UAV itself (i.e. the increase in flight altitude). After completing the energy accumulation, the increased altitude can be further converted into longer gliding distance or higher flight speed, thereby greatly expanding the operational range and loitering time of the UAV. A complete static soaring energy acquisition task is essentially a complex, multi-stage flight process, which usually includes three stages: (1) approach and search: maneuvering from normal cruising state to updraft area, determining the updraft core and accurately cutting into the updraft flight trajectory; (2) circling climb: performing optimal circling flight in the updraft core to achieve the highest efficiency of altitude gain; (3) exit and transition: after reaching the predetermined altitude, smoothly exit the circling state and convert to the best gliding attitude for flying to the next target point. How to accurately design the flight trajectory of these three stages and integrate them organically into an end-to-end, energy-optimal complete mission profile is the core challenge of engineering application of static soaring technology.

[0006] The prior art proposes to establish a mathematical model describing the vertical wind speed of thermal updrafts as a function of spatial position (radius from the core, height), such as the classical Gaussian thermal model. Secondly, a dynamic and aerodynamic model of the drone in steady coordinated turn (i.e. hover) is established. This model makes it possible to calculate the power that the drone must deliver to maintain flight at different hover radii and flight speeds, usually in the form of a parameter "sinking rate". The smaller the hover radius, the greater the roll angle required to provide sufficient centripetal force, and the greater the induced drag, resulting in a significant increase in the sinking rate of the drone. Finally, the two models are combined to build an optimization model of the net climb rate. The net climb rate is equal to the upward speed provided by the updrafts minus the sinking rate of the drone itself. The core of the prior art solution is therefore to solve, by optimal control or numerical optimization methods, the optimal hover radius and the optimal flight speed that maximize the net climb rate at any given height. The drone, by continuously tracking this optimal state point that varies dynamically with height, can achieve the most efficient energy acquisition.

[0007] However, the prior art often simplifies or ignores the complex engineering constraints faced by the UAV in actual flight when pursuing theoretical optimality. First, during complex approach and departure maneuvering flight, the UAV will experience non-steady flight, and the state parameters of its overload and roll rate must be strictly limited, but the existing scheme usually does not consider this, assuming that the UAV itself has the required maneuvering capability. Therefore, in the face of real updraft scenarios during the process of gaining energy by circling, a real UAV may not be able to perform the optimal circling strategy calculated theoretically (for example, a small radius circling that requires a large roll angle) due to its own performance limitations (for example, a maximum roll angle limit to ensure structural safety, or a minimum flight speed to avoid entering an unstable state), resulting in a serious disconnection between theoretical and actual energy gain efficiency; and the goal of the prior art is to maximize the instantaneous net climb rate, which is reasonable in the energy acquisition stage itself. However, it completely separates the "acquisition" and "use" of energy, and does not answer a more critical task-level question that determines the overall energy efficiency of the task: after completing energy acquisition, how should the accumulated height potential energy be optimally converted and allocated according to the subsequent task requirements (for example, flying to a distant target) and the flight energy consumption characteristics of the UAV itself? The existing scheme lacks an intelligent energy management decision mechanism to select from among multiple strategies such as "constant glide angle gliding throughout the journey", "optimal gliding + powered flat flight", and constant glide throughout the journey based on energy audit results, thereby minimizing the total energy consumption of the UAV's own energy system; secondly, the prior art does not solve the problem of how the UAV maneuvers from an arbitrary cruising state and precisely and smoothly cuts into the calculated optimal circling orbit. Similarly, after climbing, it also does not solve the problem of how to efficiently exit the circling and optimally convert the accumulated height potential energy into the distance of flying to the next task point. In summary, the prior art only solves a segment of the static gliding "middle", does not involve the entire complete flight process, and does not consider the flight of a real UAV in a real scenario.

[0008] Therefore, it is necessary to provide an energy-optimal aircraft static gliding full-process flight trajectory planning method to solve the above problems. SUMMARY

[0009] In view of the problem in the prior art that only a segment of the static gliding "middle" is solved, the entire complete flight process is not involved, and the flight of a real UAV in a real scenario is not considered, the present application provides an energy-optimal aircraft static gliding full-process flight trajectory planning method to solve the existing problems.

[0010] The energy-optimal aircraft static gliding full-process flight trajectory planning method of the present application adopts the following technical scheme, comprising:

[0011] An updraft model describing physical characteristics of the thermal updraft is constructed, and the vertical updraft speed at the hovering radius at any flight height is obtained by using the updraft model;

[0012] A safety constraint condition is constructed based on the range of the roll angle and the stall speed, and a flight performance model of the unpowered gliding performance of the aircraft considering the hovering maneuver is constructed based on the safety constraint condition;

[0013] The potential energy power obtained by the aircraft from the updraft is obtained according to the gravity and the vertical updraft speed when the aircraft flies in the updraft, the resistance dissipation power dissipated by the aircraft itself to overcome the resistance is obtained according to the sink rate when the aircraft hovers, and the net energy gain power of the aircraft is obtained based on the potential energy power and the resistance dissipation power;

[0014] The hovering radius corresponding to the maximum net energy gain power of the aircraft at different flight heights is taken as the optimal hovering radius at different flight heights, and the optimal roll angle and the optimal hovering airspeed corresponding to the optimal hovering radius of the aircraft at different flight heights are obtained based on the optimal hovering radius at different flight heights and by using the flight performance model;

[0015] A spiral climb trajectory is obtained based on the optimal hovering radius, the optimal roll angle and the optimal hovering airspeed corresponding to different flight heights, and the spiral climb trajectory is taken as the flight trajectory in the updraft;

[0016] An approach transition trajectory and a departure transition trajectory connecting the flight trajectory are designed based on the flight trajectory, and the flight trajectory, the approach transition trajectory and the departure transition trajectory are spliced to form a whole process flight trajectory.

[0017] The expression of the updraft model is:

[0018]

[0019] In the formula, represents the vertical wind speed of the updraft at the flight height ; represents the maximum vertical wind speed at the center of the updraft; represents the horizontal distance between the current position of the aircraft and the center of the updraft at the flight height ; represents the effective radius of the updraft at the flight height .

[0020] The expression of the maximum vertical wind speed at the center of the updraft is:

[0021]

[0022] In the formula, This indicates the maximum vertical wind speed at the center of the updraft. Indicates convection velocity; Indicates the tropospheric mixing thickness; Indicates flight altitude.

[0023] A further technical solution of the present invention is that the expression for the flight performance model is:

[0024]

[0025] In the formula, The roll angle of the unpowered hovering of the aircraft is The rate of swirling sinking at that time; For hovering airspeed; The radius of rotation; Represents gravitational acceleration; Indicates the roll angle; Indicates the minimum roll angle; Indicates the maximum roll angle; Indicates roll angle Stall speed below; Indicates the safety margin coefficient; This represents the sink rate of the aircraft during a straight descent. Airspeed; This indicates the actual maximum flight speed.

[0026] A further technical solution of the present invention is that the net power gain of the aircraft is:

[0027]

[0028] In the formula, This indicates the net energy gain of the aircraft; Indicates potential energy power; This indicates the power dissipated by resistance; Indicates the mass of the aircraft; Represents gravitational acceleration; Indicates the flight altitude h Vertical wind speed of the updraft; This indicates the slump rate when an aircraft is hovering without power.

[0029] A further technical solution of the present invention is as follows: the steps of obtaining the optimal roll angle and optimal turning airspeed corresponding to the optimal turning radius of the aircraft at different flight altitudes using a flight performance model are as follows:

[0030] The roll angle that minimizes the spiral sinking rate under the optimal spiral radius is taken as the optimal roll angle;

[0031] The optimal roll angle is used to obtain the optimal circling airspeed.

[0032] The further technical solution of the present application is that the step of designing the approach transition trajectory and the departure transition trajectory based on the flight trajectory is:

[0033] Based on the optimal circling radius, the optimal roll angle and the optimal circling airspeed corresponding to the flight trajectory at different flight altitudes, the best entry point of the flight trajectory and the flight state parameters corresponding to the best entry point are obtained, and the flight state parameters include: the optimal circling radius, the optimal roll angle and the optimal circling airspeed at the best entry point;

[0034] Based on the best entry point and the corresponding flight state parameters, and using the decoupled three-dimensional path planning path algorithm, an approach transition trajectory which is geometrically optimal and meets all terminal state constraints is generated;

[0035] A tangent disengagement strategy is adopted to plan a shortest trajectory planning adjustment trajectory to smoothly transition the aircraft from the circling flight state to the final target point as the departure transition trajectory.

[0036] The further technical solution of the present application is that the step of adopting the tangent disengagement strategy to plan a shortest trajectory planning adjustment trajectory to smoothly transition the aircraft from the circling flight state to the final target point as the departure transition trajectory is:

[0037] A tangent line is drawn from the path planning end point and the last circle circling trajectory of the aircraft in the updraft, and the tangent point of the tangent line and the circle circling trajectory is taken as a circling exit point;

[0038] A concentric circle is drawn with the updraft center as the center, and the sum of the radius of the last circle circling trajectory and the preset departure safety adjustment distance is taken as the radius, and a line connecting the path planning end point and the updraft center is drawn, and the intersection point of the line and the concentric circle is taken as a target point in the departure phase; the flight state of the target point is set to the best gliding state calculated according to the maximum lift-drag ratio of the aircraft;

[0039] Based on the circling exit point and the target point in the departure phase, a three-dimensional path planning path algorithm is used to generate a departure transition trajectory.

[0040] The further technical solution of the present application is that the optimization method of the departure transition trajectory is further included, and the steps of the optimization method are:

[0041] An energy consumption evaluation model of the aircraft in the updraft is established;

[0042] The current accumulated potential energy of the aircraft before performing gliding flight in the departure phase is obtained; it is judged whether the current accumulated potential energy is sufficient to reach the path planning end point by gliding without power;

[0043] If the current accumulated potential energy is insufficient to reach the end of the trajectory planning by unpowered gliding, the states of the gliding start position and the end position of the take-off stage are obtained, different steady gliding modes are initialized, the energy consumption of each steady gliding mode is obtained based on the energy consumption evaluation model, and the steady gliding mode corresponding to the minimum energy consumption is taken as the target steady gliding mode for gliding.

[0044] If the current accumulated potential energy is sufficient to reach the end of the trajectory planning by unpowered gliding, a glide trajectory of accelerated glide is planned to maximize the flight speed of the aircraft when reaching the end of the trajectory planning.

[0045] A further technical solution of the present application is that the expression of the energy consumption evaluation model is:

[0046]

[0047]

[0048] In the formula, represents the energy consumption of the energy system of the aircraft during gliding flight in the take-off stage; represents the output power of the energy system of the aircraft during gliding flight in the take-off stage; represents the output voltage of the energy system; represents the output current of the energy system; represents the input voltage of the electronic speed regulator; represents the input current of the electronic speed regulator; represents the input voltage of the motor; represents the input current of the motor; represents the internal resistance of the electronic speed regulator; represents the correction coefficient; represents the initial time of integration; represents the end time of integration.

[0049] The beneficial effects of the present application are:

[0050] 1. The present application constructs an ascending air flow model to make the flight process of the aircraft more suitable for the flight environment, and constructs a flight performance model that meets safety constraints to ensure that the flight performance of the unmanned aerial vehicle is optimal under the premise of safety, and then obtains a helical climb trajectory that meets the safety constraint condition as the flight trajectory in the ascending air flow, designs approach transition trajectories and take-off transition trajectories based on the flight trajectory in the ascending air flow, and thus completes the full profile trajectory planning of the aircraft. That is, the present application solves how to safely complete the flight in the actual task of the unmanned aerial vehicle in the real flight scene by deeply integrating the integrated planning framework of multiple engineering and safety constraints.

[0051] 2, The application is based on the optimal circling radius, optimal roll angle and optimal circling airspeed corresponding to the flight trajectory at different flight altitudes, obtains the best entry point of the flight trajectory and the flight state parameters corresponding to the best entry point, the flight state parameters include: the optimal circling radius, optimal roll angle and optimal circling airspeed at the best entry point; based on the best entry point and the corresponding flight state parameters, and using a decoupled three-dimensional flight path planning path algorithm, a geometrically optimal and meeting all terminal state constraints approach transition trajectory is generated; a tangent disengagement strategy is adopted to plan a shortest flight path planning adjustment trajectory to smoothly transition the aircraft from the circling flight state to the shortest flight path planning adjustment trajectory towards the final target point as the approach transition trajectory, and an energy consumption evaluation model is used to evaluate the energy at the time of departure, the gliding mode is obtained according to the energy at the time of departure, and the whole process trajectory planning of "approach-circling energy acquisition-departure" is ensured to be low in consumption and accurate, thereby providing a complete, safe, efficient and executable unmanned aerial vehicle static gliding energy acquisition solution. BRIEF DESCRIPTION OF DRAWINGS

[0052] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0053] Figure 1 The flowchart of the energy-optimal aircraft static gliding whole-process flight trajectory planning method of the present application is shown in the figure.

[0054] Figure 2 The vertical wind speed distribution diagram under different flight altitudes for the embodiment of the present application is shown in the figure. = 6 m / s , =500 m The vertical wind speed distribution diagram under different flight altitudes for the embodiment of the present application is shown in the figure.

[0055] Figure 3 The vertical wind speed distribution diagram under different flight altitudes for the embodiment of the present application is shown in the figure. = 6 m / s , =500 m and =200 m The vertical wind speed distribution diagram under different flight altitudes for the embodiment of the present application is shown in the figure.

[0056] Figure 4 The relationship between circling sink rate and circling airspeed under different roll angles in the embodiment of the present application is shown in the figure.

[0057] Figure 5 The relationship between circling sink rate and circling airspeed under different roll angles in the embodiment of the present application is shown in the figure.

[0058] Figure 6 FIG. 1 is a schematic diagram of the relationship between the optimal circling airspeed, the optimal roll angle and the circling radius in an embodiment of the present application;

[0059] Figure 7 FIG. 2 is a schematic diagram of the relationship between the resistance consumption power and the circling radius in an embodiment of the present application;

[0060] Figure 8 FIG. 3 is a schematic diagram of the relationship between the net energy gain power and the circling radius in an embodiment of the present application;

[0061] Figure 9 FIG. 4 is a schematic diagram of the take-off flight path planning of the aircraft in the ascending airflow flight environment in an embodiment of the present application. DETAILED DESCRIPTION

[0062] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts fall within the scope of the present application.

[0063] An embodiment of the energy-optimal aircraft static gliding whole-process flight path planning method of the present application, as shown in FIG. 1, comprises the following steps. Figure 1

[0064] S1, obtaining the vertical ascending wind speed at the circling radius of any flight height;

[0065] Specifically, an ascending airflow model describing the physical characteristics of the ascending airflow is constructed, and the vertical ascending wind speed at the circling radius of any flight height is obtained by using the ascending airflow model.

[0066] Specifically, in a specific embodiment, in order to effectively utilize the environmental energy, an ascending airflow model capable of accurately describing the physical characteristics of the ascending airflow is first established, and the ascending airflow model is the basis for subsequent energy-gaining strategy analysis and path planning. The ascending airflow is characterized as a relatively regular columnar airflow structure in space, and the key is that the ascending airflow model dynamically reflects the variation law of the ascending airflow intensity and shape with the flight height. Specifically, the ascending airflow model describes the distribution characteristics of the vertical ascending wind speed on the horizontal cross section at any flight height by a mathematical function: the wind speed reaches the strongest at the center point of the ascending airflow, and decays in a nonlinear, Gaussian-like distribution to the periphery. The core assumption of the ascending airflow model is that at any flight height , the vertical wind speed of the ascending airflow is Gaussian distributed around the center point on the horizontal cross section, and the intensity is proportional to the horizontal distance ​The relationship between the maximum vertical wind speed at the center of the updraft and the average velocity is given by

[0067] (1)

[0068] where, represents the vertical wind speed of the updraft at the flight altitude ; represents the maximum vertical wind speed at the center of the updraft; represents the horizontal distance from the center of the updraft to the current position of the aircraft at the flight altitude ; represents the effective radius of the updraft at the flight altitude . It is affected by two key parameters, the tropospheric mixing depth and the convection velocity , and is given by

[0069] (2)

[0070] (3)

[0071] where, represents the average velocity.

[0072] The relationship between the maximum vertical wind speed at the center of the updraft and the average velocity can be established by integrating equation (1) over the entire radius, which is given by

[0073] (4)

[0074] (5)

[0075] where, represents the maximum vertical wind speed at the center of the updraft.

[0076] Substituting equation (5) into equation (3), the expression for the maximum vertical wind speed at the center of the updraft at the flight altitude is given by

[0077] (6)

[0078] where, represents the tropospheric mixing depth; represents the convection velocity.

[0079] To quantify and visualize the physical characteristics of the updraft model, we select = 6 m / s , =500 m The simulation results obtained as simulation parameters of the ascending airflow model are shown in FIGS. 6 and 7. Figure 2 and Figure 3 From FIGS. 6 and 7, it can be seen that by establishing the ascending airflow model dynamically changing with the height, the embodiment provides precise and reliable environmental energy field data input for the aircraft to formulate the optimal energy acquisition strategy in different height layers, and can accurately describe the variation characteristics of the ascending airflow in the real low-altitude flight environment. Figure 2 and Figure 3

[0080] Thus, the vertical ascending wind speed at the hovering radius of any flight height can be obtained by using the ascending airflow model.

[0081] S2, constructing a flight performance model of the unpowered gliding performance of the aircraft considering the hovering maneuver;

[0082] For example, in a specific embodiment, a safety constraint condition is constructed based on the range of the roll angle and the stall speed, and a flight performance model of the unpowered gliding performance of the aircraft considering the hovering maneuver is constructed based on the safety constraint condition, wherein the steps of constructing the flight performance model are as follows:

[0083] After the ascending airflow model in the real low-altitude flight scenario is established, the flight performance model capable of accurately quantifying the “energy consumption” of the aircraft in the flight process is further established, and the flight performance model is the key to the energy balance analysis and the final judgment of whether the energy net gain can be realized in the flight process of the aircraft. First, the baseline gliding performance of the aircraft under the windless and unpowered condition is modeled. The steady-state straight (fixed straight) descent state of the aircraft under the condition of no sideslip, no roll, and no yaw is considered, in which state the aircraft is not affected by any asymmetric force or moment, i.e., the lateral dynamics is ignored in the embodiment, and only the force balance in the longitudinal plane is considered, and the force and moment balance equation set is as follows:

[0084] (7)

[0085] In the formula, L is the lift; D is the drag; M is the pitching moment; m is the mass of the aircraft; g is the acceleration of gravity; γ is the track inclination angle (negative value when gliding). The lift L, the drag D, and the pitching moment M are all related to the flight state (especially the airspeed V and the angle of attack α) and the control input (the elevator deflection angle δe). ​​​​​​​ ), and the series of equilibrium points are obtained by solving the equations, thus the sink rate of the aircraft in the straight glide state is constructed as:

[0086] (8)

[0087] where, is the sink rate of the aircraft in the straight glide state; is the flight airspeed; is the quadratic term coefficient of the polynomial function of the sink rate about the flight airspeed; is the linear term coefficient of the polynomial function of the sink rate about the flight airspeed; is the constant of the polynomial function of the sink rate about the flight airspeed.

[0088] The expression of equation (8) accurately reveals the relationship between the sink rate of the aircraft and its flight airspeed, which is the inherent energy dissipation characteristic of the aircraft. The sink rate is extended to the hover flight mode of the aircraft for energy acquisition in the ascending airflow environment. When the aircraft is converted from the straight glide to the hover glide, the lift must be increased to provide the centripetal force to maintain the coordinated turn, which inevitably leads to the changes of the flight airspeed and the sink rate. For the steady-state coordinated turn (no sideslip), the roll angle of the aircraft must satisfy the following force balance relationship between the lift and the gravity

[0089] (9)

[0090] Equation (9) shows that the lift in the hover must be increased to . Based on the lift equation and assuming that the aircraft works at the same aerodynamic angle of attack in the straight and hover states, the aircraft in the hover state has:

[0091] (10)

[0092] (11)

[0093] where, is the hover airspeed when the roll angle is ; and is the hover sink rate when the roll angle is .

[0094] ​Formulas (7)-(11) reflect two core effects of hovering maneuvers: first, to maintain altitude, flight speed must be increased; second, at the same airspeed, the sinking rate will increase significantly. For actual static gliding missions, the hovering radius is more valuable, as its size directly determines whether the aircraft can effectively maintain itself within the core region of the updraft. In steady-state coordinated turns, the hovering radius is determined by the hovering airspeed and roll angle, as shown in the following formula:

[0095] (12)

[0096] In the formula, The radius of rotation; For hovering airspeed; For roll angle; This is the acceleration due to gravity.

[0097] By combining equations (10), (11), and (12), we can obtain the relationship between the swirl sink rate and the swirl airspeed and swirl radius at different roll angles. The relationship between the swirl sink rate and the swirl airspeed and swirl radius is as follows: Figure 4 and Figure 5 As shown, Figure 4 and Figure 5 All curves in the diagram have taken into account the stall speed limit of a real aircraft, and only the speed and radius range under physical flyable constraints have been plotted.

[0098] When the turning radius is small, the minimum sink rate often lies on the stall boundary. In actual flight, flying along the stall boundary for an extended period is extremely unsafe, as even a minor disturbance can lead to a stall. Therefore, to develop an engineering-feasible and robust flight strategy, a stall safety margin factor must be introduced based on theoretical optimization. In this embodiment, a safety margin factor is introduced. (taken here) = 1.1) Requirement for the aircraft's turning airspeed Must always satisfy ,in This is the stall speed at that roll angle. Under this safety constraint, by Figure 4 and Figure 5 It can be seen that for any given spiral radius There exists an optimal roll angle that minimizes the absolute value of the descent rate. The process of finding this optimal flight state is transformed into a constrained inverse optimization mathematical problem. The objective of this inverse optimization mathematical problem is a given descent radius... Then, at all feasible roll angles In the process, we find an absolute value that allows the spiraling sinking rate to be maximized. To achieve the minimum optimal roll angle , and then the optimal circling airspeed required to achieve the optimal performance is determined, and the flight performance model is:

[0099] (13)

[0100] wherein, is the sink rate of the aircraft when the roll angle is ; is the circling airspeed; is the circling radius; denotes the gravitational acceleration; denotes the roll angle; denotes the minimum roll angle; denotes the maximum roll angle; denotes the stall speed at the roll angle ; denotes the safety margin coefficient; is the sink rate of the aircraft in the straight glide state; is the flight airspeed; denotes the actual maximum flight speed; and are safety constraint conditions.

[0101] By traversing a series of target circling radii, the optimal circling airspeed and the optimal roll angle of the aircraft under the safety constraint conditions can be obtained. Specifically, it can be known from Figure 6 that for any feasible circling radius, there is a corresponding optimal circling airspeed and optimal roll angle.

[0102] Thus, the embodiment establishes a complete database covering the flight performance from the straight flight to the circling flight at different roll angles and the multi-dimensional gliding performance. The database provides a flight performance model for the subsequent accurate calculation of the power dissipation of the resistance (energy cost) of the aircraft in any flight state.

[0103] S3, obtaining the net energy gain power of the aircraft;

[0104] Specifically, the potential energy power obtained by the aircraft from the uplift airflow is obtained according to the gravity and the vertical uplift wind speed when the aircraft is flying in the uplift airflow; the resistance dissipation power dissipated by the aircraft itself to overcome the resistance is obtained according to the sink rate of the aircraft when the aircraft is circling without power; and the net energy gain power of the aircraft is obtained based on the potential energy power and the resistance dissipation power.

[0105] Exemplarily, in a specific embodiment, based on the uplift airflow model established in step S1 and the aircraft performance model established in step S2, the optimal circling flight state that can maximize the net energy gain power of the aircraft is searched under the premise of meeting the actual engineering constraints, that is, firstly, the potential energy power obtained by the aircraft from the uplift airflow is defined the drag dissipation power dissipated by the aircraft in overcoming the drag force; the potential energy power and the drag dissipation power as the net energy gain power then we have:

[0106] (14)

[0107] (15)

[0108] (16)

[0109] wherein, represents the net energy gain power of the aircraft; represents the potential energy power; represents the drag dissipation power; represents the mass of the aircraft; represents the gravitational acceleration; represents the vertical wind speed of the updraft at the flight altitude h ; and represents the sink rate of the aircraft in unpowered circling.

[0110] S4, obtaining the optimal roll angle and the optimal circling airspeed corresponding to the optimal circling radius of the aircraft at different flight altitudes;

[0111] Specifically, the circling radius corresponding to the maximum net energy gain power of the aircraft at different flight altitudes is taken as the optimal circling radius at different flight altitudes, and the optimal roll angle and the optimal circling airspeed corresponding to the optimal circling radius of the aircraft at different flight altitudes are obtained based on the optimal circling radius at different flight altitudes and by using the flight performance model.

[0112] For example, in one specific embodiment, the step of obtaining the circling radius corresponding to the maximum net energy gain power of the aircraft at different flight altitudes is as follows:

[0113] As can be seen from the updraft model, the vertical wind speed of the updraft is determined by the circling radius and the flight altitude h , i.e.,

[0114] (17)

[0115] wherein, represents the vertical wind speed of the updraft at the flight altitude ; and represents the maximum vertical wind speed at the center of the updraft; represents the circling radius of the aircraft.h Indicates flight altitude; Indicates the updraft at flight altitude The effective radius at that location; Indicates the tropospheric mixing thickness; This indicates the convection velocity.

[0116] Depend on Figure 6 Furthermore, as can be seen from the inverse optimization mathematical problem, for a given spiral radius... There exists an optimal set of hovering airspeed and roll angle that results in an unpowered hovering sink rate for the aircraft. The absolute value is the smallest, therefore, iterate through all the spiral radii. The minimum absolute value of the drag dissipation power that can be obtained is about the radius of rotation. The function expression:

[0117] (18)

[0118] In the formula, This represents the minimum absolute value of the power dissipated by resistance. Indicates the mass of the aircraft; Represents gravitational acceleration; This represents the minimum absolute value of the swirl rate when an aircraft is circling without power. Specifically, the trend of minimum drag power dissipation with swirl radius is as follows: Figure 7 As shown. From Figure 7 It can be seen that for each given turning radius, there exists a unique resistance dissipation power corresponding to it. That is, for each given turning radius, there exists a theoretically achievable maximum net energy gain value, and this relationship is defined as:

[0119] (19)

[0120] In the formula, This indicates the aircraft's maximum net power gain. Indicates potential energy power; This represents the minimum absolute value of the power dissipated by resistance; Indicates the mass of the aircraft; Represents gravitational acceleration; Indicates the flight altitude h Vertical wind speed of the updraft; This represents the minimum absolute value of the spiral descent rate when an aircraft is hovering without power.

[0121] It should be noted that at a given flight altitude Under the condition that, for any given spiral radius Since the wind energy harvested is a constant, and the absolute value of the power dissipated by resistance has a minimum, the net harvested power has a maximum value, traversing the circumference radius. The turning radius corresponding to the maximum net energy gain can be obtained. The functional expression for the maximum net energy gain of an aircraft, under specific thermal updraft environments and flight altitudes, is as follows: Figure 8 As shown, Figure 8 As shown, different spiral radii Corresponding to different vertical wind speeds and different absolute values ​​of minimum spiraling sinking rate Traverse the radius of the spiral This yields a curve showing the maximum net power gain at a given hovering radius as a function of the radius. Each hovering radius corresponds to a specific maximum net power gain for the aircraft, but the maximum net power gain varies across different hovering radii. Figure 8 It can be seen that, Figure 8 The green line in the diagram has a distinct peak, which is the point of maximum energy gain. The spiral radius corresponding to the point of maximum energy gain is the optimal spiral radius. This is equivalent to finding a "global optimal solution" among all possible "local optimal solutions".

[0122] S5. Obtain the flight path in the updraft;

[0123] Specifically, the spiral climb trajectory is obtained based on the optimal hovering radius, optimal roll angle and optimal hovering airspeed corresponding to different flight altitudes, and this spiral climb trajectory is used as the flight trajectory in the updraft.

[0124] For example, in one specific embodiment, after comprehensively analyzing the aircraft's own performance and the updraft environment according to steps S1-S4, it can be determined that under this specific operating condition, there exists a unique optimal hovering state (a parameter combination of optimal hovering radius, optimal hovering speed, and optimal roll angle) that enables the aircraft to achieve maximum energy harvesting efficiency. Figure 2 As shown, the vertical wind speed of the updraft With flight altitude The aircraft exhibits a non-monotonic variation pattern of first increasing and then decreasing. This characteristic directly determines that the aircraft has a range of climbable altitudes. At extremely low altitudes near the ground, the updraft is not yet fully developed and its strength is insufficient to overcome the aircraft's minimum descent rate. Only when the aircraft climbs to a certain altitude and the updraft is strong enough can its net power gain become positive. This embodiment sets a climb initiation power threshold. By searching upwards from low altitude, the first lowest altitude that can meet this power requirement is determined as the starting point of the climb, i.e., the initial lower limit of altitude. As the altitude continues to increase, the thermal airflow begins to gradually decay after reaching its peak strength. When the decayed rising airflow strength is not enough to overcome the sink rate of the aircraft at a certain altitude, it is considered that the aircraft can no longer effectively climb, and this altitude is defined as the theoretical energy ceiling. In the actual climbing process, as the flight altitude changes, the strength of the rising airflow and the radius, air density will change, so the optimal circling state (the parameter combination of the optimal circling radius, the optimal circling speed and the optimal roll angle) at each flight altitude also dynamically changes. The embodiment introduces engineering constraints including the minimum circling radius and the maximum roll angle , so that the optimal strategy obtained in the optimization solution at any flight altitude is strictly located within the constraint boundary, so that the aircraft can convert the vertical kinetic energy of the rising airflow into its potential energy in the most safe and efficient way.

[0125] So far, based on the optimal circling radius, the optimal roll angle and the optimal circling airspeed corresponding to different flight altitudes determined in step S4, the helical climbing trajectory can be obtained, and the helical climbing trajectory is taken as the flight trajectory in the rising airflow.

[0126] S6, obtaining a whole-process flight trajectory;

[0127] Specifically, based on the flight trajectory, approach transition trajectory and departure transition trajectory connecting the flight trajectory are designed, and the flight trajectory, approach transition trajectory and departure transition trajectory are spliced to form the whole-process flight trajectory.

[0128] For example, in a specific embodiment, the step of designing the approach transition trajectory and the departure transition trajectory connecting the flight trajectory based on the flight trajectory is: based on the optimal circling radius, the optimal roll angle and the optimal circling airspeed corresponding to the flight trajectory at different flight altitudes, the best entry point of the flight trajectory and the flight state parameters corresponding to the best entry point are obtained, the flight state parameters include: the optimal circling radius, the optimal roll angle and the optimal circling airspeed at the best entry point; based on the best entry point and the flight state parameters corresponding thereto, and using a decoupled three-dimensional flight path planning path algorithm, an approach transition trajectory which is geometrically optimal and meets all terminal state constraints is generated; a tangent departure strategy is adopted to plan a shortest flight path planning adjustment trajectory to smoothly transition the aircraft from the circling flight state to the shortest flight path planning adjustment trajectory towards the final target point as the departure transition trajectory.

[0129] For example, in a specific embodiment, the step of designing the approach transition trajectory and the departure transition trajectory connecting the flight trajectory based on the flight trajectory is: based on the optimal circling radius, the optimal roll angle and the optimal circling airspeed corresponding to the flight trajectory at different flight altitudes, the best entry point of the flight trajectory and the flight state parameters corresponding to the best entry point are obtained, the flight state parameters include: the optimal circling radius, the optimal roll angle and the optimal circling airspeed at the best entry point; based on the best entry point and the flight state parameters corresponding thereto, and using a decoupled three-dimensional flight path planning path algorithm, an approach transition trajectory which is geometrically optimal and meets all terminal state constraints is generated; a tangent departure strategy is adopted to plan a shortest flight path planning adjustment trajectory to smoothly transition the aircraft from the circling flight state to the shortest flight path planning adjustment trajectory towards the final target point as the departure transition trajectory. Figure 9As shown, in this embodiment, the tangent departure strategy is adopted. The steps for planning and adjusting the shortest trajectory to smoothly transition the aircraft from a hovering flight state to the final target point as the exit transition trajectory are as follows: from the trajectory planning endpoint (i.e. Figure 9 Draw a tangent line between the target point of the flight path planning and the aircraft's final spiral trajectory in the updraft. The point where this tangent line intersects the final spiral trajectory is taken as the recovery point (i.e., the point where the aircraft recovers from the spiral). Figure 9 The mid-circle recovery point is used as the starting point for trajectory planning. A concentric circle is drawn with the center of the updraft as the center and the radius of the sum of the radius of the last circling trajectory and the preset exit safety adjustment distance as the radius. The line connecting the trajectory planning endpoint and the updraft center is used as the intersection of the line and the concentric circle as the target point for the exit phase. The flight state of the target point is set to the optimal gliding state calculated based on the aircraft's maximum lift-to-drag ratio. Based on the mid-circle recovery point, the target point for the exit phase, and using a three-dimensional trajectory planning path algorithm, an exit transition trajectory is generated.

[0130] For example, in one specific embodiment, the method further includes an optimization method for the exit transition trajectory. The optimization method comprises the following steps: establishing an energy consumption assessment model for the aircraft in an updraft; obtaining the current accumulated potential energy of the aircraft before performing gliding flight in the exit phase; determining whether the currently accumulated potential energy is sufficient to glide to the end point of the planned trajectory without power; if the currently accumulated potential energy is insufficient to glide to the end point of the planned trajectory without power, obtaining the state of the gliding start position and end position in the exit phase, initializing different steady gliding modes, obtaining the energy consumption of each steady gliding mode based on the energy consumption assessment model, and using the steady gliding mode corresponding to the minimum energy consumption as the target steady gliding mode for gliding; if the currently accumulated potential energy is sufficient to glide to the end point of the planned trajectory without power, planning an accelerated gliding trajectory to maximize the flight speed of the aircraft when reaching the end point of the planned trajectory.

[0131] In this embodiment, the step of establishing an energy consumption assessment model for the aircraft in an updraft is as follows: after knowing the thrust required for the aircraft to glide during its exit maneuver, the propeller speed can be derived based on the propeller blade element momentum theory. and propeller thrust Satisfies the nonlinear equation system:

[0132] (20)

[0133] In the formula: Indicates propeller thrust; Indicates the thrust coefficient of the propeller; Indicates air density; Indicates the propeller speed; Indicates the propeller diameter; Indicates the forward ratio; is the free-stream velocity perpendicular to the propeller disc plane; is a quadratic coefficient of the polynomial function of the drag coefficient with respect to the advance ratio ; is a linear coefficient of the polynomial function of the drag coefficient with respect to the advance ratio ; is a constant of the polynomial function of the drag coefficient with respect to the advance ratio ; is a quadratic coefficient of the polynomial function of the torque coefficient with respect to the advance ratio ; ;

[0134] After the propeller speed and the advance ratio are obtained, the propeller torque M is:

[0135] (21)

[0136] wherein, denotes the propeller torque; is the propeller torque coefficient; denotes the air density; denotes the propeller speed; denotes the propeller diameter; denotes the advance ratio; is the free-stream velocity perpendicular to the propeller disc plane; is a quadratic coefficient of the polynomial function of the torque coefficient with respect to the advance ratio ; ; is a linear coefficient of the polynomial function of the torque coefficient with respect to the advance ratio ; ; is a constant of the polynomial function of the torque coefficient with respect to the advance ratio ; ; is a quadratic coefficient of the polynomial function of the torque coefficient with respect to the advance ratio ; ;

[0137] Considering that the descent segment is a long-time process and the energy consumption evaluation model aims to analyze the energy consumption of the UAV in the whole flight process, the dynamic adjustment process of the speed is ignored, i.e., the speed and the torque of the brushless direct-current motor are always equal to the speed and the torque of the propeller, and according to the brushless direct-current motor model, at this time, the input voltage and the input current of the motor are:

[0138] (22)

[0139] (23)

[0140] wherein, denotes the propeller torque; denotes the propeller speed; This indicates the input voltage of the motor; This indicates the input current of the motor; This represents the motor speed constant; Indicates the rated no-load voltage of the motor; This indicates the motor's rated no-load current; Indicates the interphase internal resistance of the motor; , , , These are all inherent parameters of the motor, obtained from technical data provided by the manufacturer. The electronic speed controller (ESC), as a device that adjusts the motor's input voltage and current based on the throttle signal, has the following relationship between its output voltage and current and the motor's input voltage and current:

[0141] (twenty four)

[0142] In the formula, Indicates the output current of the ESC; This indicates the input voltage of the motor; This indicates the input current of the motor; Indicates the output voltage of the ESC; R e The internal resistance of the ESC; the ESC (Electronic Speed Control, ESC) Upon receiving the throttle signal from the flight control system Then, the DC voltage of the energy system is converted to a voltage without speed feedback. BLDC Pulse width modulation of motor ( PWM Voltage; in this embodiment, the aircraft is a drone, and the drone's energy system is a battery, that is, the process expression is:

[0143] (25)

[0144] In the formula, Indicates the battery's output voltage; Indicates the input voltage of the ESC; Indicates the battery output current; Indicates the input current of the ESC; Indicates the correction factor; This indicates the input current of the motor; This indicates the throttle signal.

[0145] Therefore, given the known thrust requirement T After determining the model and specifications of the drone's ESC, motor, and propellers, the energy consumption assessment model is as follows:

[0146] (26)

[0147] In the formula, represents the energy consumption of the energy system when the aircraft is gliding in the take-off phase; represents the output power of the energy system when the aircraft is gliding in the take-off phase; represents the output voltage of the energy system; represents the output current of the energy system; represents the input voltage of the electronic speed controller; represents the input current of the electronic speed controller; represents the input voltage of the electric motor; represents the input current of the electric motor; represents the internal resistance of the electronic speed controller; represents the correction factor; represents the initial time of integration; represents the final time of integration.

[0148] For example, in the present embodiment, if the currently accumulated potential energy is sufficient to reach the end point of the flight path planning without power gliding, and the potential energy reserve is much more than required, if still according to the maximum glide ratio corresponding to the maximum lift-drag ratio, the target point will be flown over. Therefore, in the present embodiment, a steeper glide angle will be recalculated, which is just enough to accurately connect the start point and the end point, and the aircraft will perform an accelerated glide along this path, and when reaching the end point, the excess potential energy is converted into higher kinetic energy (airspeed).

[0149] (27)

[0150] (28)

[0151] (29)

[0152] wherein, represents the mass of the aircraft; represents the drag force received by the aircraft; represents the lift force received by the aircraft; represents the gravitational acceleration; represents the air density; represents the flight path inclination angle (glide angle); represents the rate of change of the flight path inclination angle; represents the flight path azimuth angle; represents the rate of change of the flight path azimuth angle; represents the airspeed of the aircraft; represents the rate of change of the airspeed of the aircraft; represents the roll angle; represents the angle of attack; represents the zero-lift angle of attack (i.e. the lift coefficient when the angle of attack = 0); denotes zero-lift drag coefficient; denotes lift line slope, i.e. the rate of change of lift coefficient with respect to angle of attack; denotes induced drag factor; denotes lift coefficient, denotes drag coefficient; denotes wing area.

[0153] Since the whole process is a non-powered and non-sideslip, non-rolling, constant glide angle straight glide, the rate of change of track angle is 0, the roll angle and its rate of change are 0, so the equation is simplified as:

[0154] (30)

[0155] In the formula, denotes the mass of the aircraft; denotes the drag received by the aircraft; denotes the lift received by the aircraft; denotes the acceleration of gravity; denotes air density; denotes the track inclination (glide angle); denotes the airspeed of the aircraft; denotes the rate of change of airspeed of the aircraft; denotes the angle of attack; denotes the lift coefficient, denotes the drag coefficient; denotes the wing area; the glide angle is known, the lift , the lift coefficient is calculated by formula (30), and the angle of attack at this time is inversely deduced , i.e. the drag is calculated, then the current acceleration can be calculated according to the third formula in formula (30), based on the airspeed and acceleration at the current time, the airspeed at the next time can be obtained, and the airspeed and acceleration at each time can be obtained by repeating the calculation.

[0156] In summary, the present application constructs a complete closed-loop technical scheme from environmental perception, self-performance modeling to strategy optimization, and then to full profile trajectory planning and intelligent energy management, which significantly improves the energy utilization efficiency and task autonomy of the unmanned aerial vehicle in long-endurance tasks.

[0157] The above only describes the preferred embodiments of the present application and should not be used to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for planning the flight trajectory of an energy-optimal aircraft during the entire static gliding process, characterized in that, include: Construct an updraft model to describe the physical characteristics of thermal updrafts, and use the updraft model to obtain the vertical updraft speed at the vortex radius at any flight altitude; Based on the range of roll angle and stall speed, safety constraints are constructed, and based on the safety constraints, a flight performance model of the aircraft considering the unpowered gliding performance of the aircraft with circling maneuvers is constructed. The potential energy power gained by the aircraft from the updraft is obtained based on gravity and vertical updraft speed when the aircraft is flying in the updraft; the drag dissipation power dissipated by the aircraft itself to overcome drag is obtained based on the swirl rate when the aircraft is hovering without power; and the net energy gain power of the aircraft is obtained based on the potential energy power and drag dissipation power. The turning radius corresponding to the maximum net energy gain of the aircraft at different flight altitudes is taken as the optimal turning radius at different flight altitudes. Based on the optimal turning radius at different flight altitudes and using the flight performance model, the optimal roll angle and optimal turning airspeed corresponding to the optimal turning radius of the aircraft at different flight altitudes are obtained. Based on the optimal turning radius, optimal roll angle and optimal turning airspeed at different flight altitudes, the spiral climb trajectory is obtained and used as the flight trajectory in the updraft. Based on the flight trajectory design, the approach transition trajectory and the exit transition trajectory are connected to form the entire flight trajectory.

2. The energy-optimal flight trajectory planning method for the entire static gliding process of an aircraft according to claim 1, characterized in that, The expression for the updraft model is: In the formula, Indicates the flight altitude Vertical wind speed of the updraft; This indicates the maximum vertical wind speed at the center of the updraft. Indicates the flight altitude of the aircraft The current horizontal distance from the center of the updraft; Indicates the updraft at flight altitude The effective radius at that location.

3. The energy-optimal flight trajectory planning method for the entire static gliding process of an aircraft according to claim 2, characterized in that, The expression for the maximum vertical wind speed at the center of the updraft is: In the formula, This indicates the maximum vertical wind speed at the center of the updraft. Indicates convection velocity; Indicates the tropospheric mixing thickness; Indicates flight altitude.

4. The energy-optimal flight trajectory planning method for the entire static gliding process of an aircraft according to claim 1, characterized in that, The expression for the flight performance model is: In the formula, The roll angle of the unpowered hovering of the aircraft is The rate of swirling sinking at that time; For hovering airspeed; The radius of rotation; Represents gravitational acceleration; Indicates the roll angle; Indicates the minimum roll angle; Indicates the maximum roll angle; Indicates roll angle Stall speed below; Indicates the safety margin coefficient; This represents the sink rate of the aircraft during a straight descent. Airspeed; Indicates the actual maximum flight speed; and For safety constraints.

5. The energy-optimal flight trajectory planning method for the entire static gliding process of an aircraft according to claim 1, characterized in that, The net energy gain of the aircraft is: In the formula, This indicates the net energy gain of the aircraft; Indicates potential energy power; This indicates the power dissipated by resistance; Indicates the mass of the aircraft; Represents gravitational acceleration; Indicates the flight altitude h Vertical wind speed of the updraft; This indicates the slump rate when an aircraft is hovering without power.

6. The energy-optimal flight trajectory planning method for the entire static gliding process of an aircraft according to claim 1, characterized in that, The steps for obtaining the optimal roll angle and optimal turn speed corresponding to the optimal turn radius at different flight altitudes, and using a flight performance model, are as follows: The roll angle that minimizes the spiral sinking rate under the optimal spiral radius is taken as the optimal roll angle; The optimal hovering airspeed is obtained based on the optimal roll angle.

7. The energy-optimal flight trajectory planning method for the entire static gliding process of an aircraft according to claim 1, characterized in that, The steps for designing the approach and exit transition trajectories based on the flight trajectory are as follows: Based on the optimal turning radius, optimal roll angle and optimal turning airspeed corresponding to the flight trajectory at different flight altitudes, the optimal entry point of the flight trajectory and the flight state parameters corresponding to the optimal entry point are obtained. The flight state parameters include: the optimal turning radius, optimal roll angle and optimal turning airspeed at the optimal entry point. Based on the optimal entry point and its corresponding flight state parameters, and using a decoupled 3D trajectory planning path algorithm, a geometrically optimal approach transition trajectory that satisfies all terminal state constraints is generated. A tangential departure strategy is adopted, and a shortest trajectory is planned to smoothly transition the aircraft from hovering to the final target point as the exit transition trajectory.

8. The energy-optimal flight trajectory planning method for the entire static gliding process of an aircraft according to claim 7, characterized in that, Using a tangential departure strategy, the steps for planning and adjusting the trajectory to serve as the exit transition trajectory for the aircraft are as follows: Draw a tangent line from the end point of the flight path planning and the last loop trajectory of the aircraft in the updraft. The point where this tangent line is tangent to the loop trajectory is the loop recovery point. With the center of the updraft as the center, draw a concentric circle with the radius of the sum of the radius of the last circling trajectory and the preset exit safety adjustment distance as the radius. Connect the end point of the flight path planning and the center of the updraft, and take the intersection of the line and the concentric circle as the target point of the exit phase. The flight state of the target point is set as the optimal gliding state calculated based on the maximum lift-to-drag ratio of the aircraft. Based on the turning point and the target point of the exit phase, and using a three-dimensional trajectory planning algorithm, an exit transition trajectory is generated.

9. The energy-optimal flight trajectory planning method for the entire static gliding process of an aircraft according to claim 7, characterized in that, It also includes an optimization method for the exit transition trajectory, the steps of which are as follows: Establish an energy consumption assessment model for aircraft in updrafts; Obtain the current accumulated potential energy of the aircraft before it performs its gliding flight during the departure phase; determine whether the current accumulated potential energy is sufficient for unpowered gliding to reach the destination of the planned flight path; If the current accumulated potential energy is insufficient to glide to the end of the planned trajectory without power, the state of the gliding start position and end position in the departure phase is obtained, different steady gliding modes are initialized, the energy consumption of each steady gliding mode is obtained based on the energy consumption assessment model, and the steady gliding mode corresponding to the minimum energy consumption is used as the target steady gliding mode for gliding. If the accumulated potential energy is sufficient for unpowered gliding to the end of the planned trajectory, then a gliding trajectory with accelerated descent will be planned to maximize the aircraft's speed when it reaches the end of the planned trajectory.

10. The energy-optimal flight trajectory planning method for the entire static gliding process of an aircraft according to claim 9, characterized in that, The expression for the energy consumption assessment model is: In the formula, This indicates the energy consumption of the aircraft's energy system during the gliding flight phase of the aircraft's departure phase; This indicates the output power of the energy system during the gliding flight phase of the aircraft's departure phase; Indicates the output voltage of the energy system; Indicates the output current of the energy system; Indicates the input voltage of the electronic speed controller; Indicates the input current of the electronic speed controller; This indicates the input voltage of the motor; This indicates the input current of the motor; Indicates the internal resistance of the electronic speed controller; Indicates the correction factor; Indicates the initial time of integration; This indicates the time at which the integration ends.

Images