A guidance method for the recovery of an aircraft by hitting a net in the air

Abstract

The present invention discloses a guidance method and system for aerial net-capturing recovery of an aircraft. The method provided by the present invention divides the net-capturing flight path into p segments, and controls the aircraft to execute different control instructions on the p-th segment and the q-th segment of the flight path to achieve the net-capturing recovery process of the aircraft, where p is an integer greater than or equal to 2, and q represents at least one of 1 to p-1. The present invention can not only ensure the safety of the net-capturing structure but also improve the efficiency of the recovery operation.

Description

Technical Field

[0001] The present invention relates to the technical field of aircraft control, and in particular, to a guidance method and system for aerial netting recovery of an aircraft. Background Art

[0002] Currently, the traditional recovery methods of aircraft include ground recovery methods such as netting, wire striking, parachute, runway landing, and vertical landing. However, restricted by the recovery site, traditional recovery methods cannot be carried out in places such as jungles, mountains, and water surfaces, which greatly limits the use of aircraft.

[0003] The advantage of aerial recovery is that it can expand the combat radius of the aircraft, ensure that the friendly side improves the regional intervention and denial capabilities under safe conditions; break through the limitation of the recovery site, and the entire recovery process can be completed maneuverably, which greatly facilitates the rapid departure of cluster aircraft from the mission area after the mission is completed.

[0004] Aerial netting recovery is one of the main aerial recovery methods. When performing aerial netting recovery, generally, a catch net is extended below the carrier aircraft or a capture net is towed behind the carrier aircraft to wait for the aircraft to hit the net. Aerial netting recovery has the advantages of being fast, efficient, having low technical requirements, and being convenient for multiple aircraft to perform simultaneously.

[0005] In order to improve the success rate of aerial netting recovery, generally, the state of the aircraft and the carrier aircraft needs to be adjusted on the netting route before recovery. At the same time, the time available for recovery in the netting route is limited, and the recovery speed is slow, which is not conducive to the continuity and efficiency of aerial netting recovery. Summary of the Invention

[0006] In view of the problems existing in the above-mentioned prior art, the present invention provides a guidance method and system for aerial netting recovery of an aircraft.

[0007] To achieve the above object, in a first aspect, the present invention provides a guidance method for aerial netting recovery of an aircraft, which is used to divide the netting route into p segments, and control the aircraft to execute different control instructions on the p-th segment route and the q-th segment route to realize the netting recovery process of the aircraft, where p is an integer greater than or equal to 2, and q represents at least one of 1 to p - 1.

[0008] In a second aspect, the present invention provides a guidance system for aerial netting recovery of an aircraft. The system includes:

[0009] A route division module, which is used to divide the netting route into p segments, and set the p-th segment route as a horizontal circular trajectory, where the p-th segment route is tangent to the initial velocity of the capture net and tangent to the (p - 1)-th segment route;

[0010] An execution module, which is used to control the flight of the aircraft based on speed constraints and / or collision angle constraints during the q-th flight path segment, and to control the aircraft to fly along the p-th flight path segment during the p-th flight path segment, so that the aircraft catches up with and collides with the net for recovery.

[0011] The beneficial effects of a guidance method and system for in-air net-catch recovery of an aircraft according to the present invention include:

[0012] (1) The method of the present invention improves the problem of low recovery efficiency in the previous net-catch recovery that requires pre-entry into the flight path in advance, and is particularly suitable for in-air net-catch recovery in a state where the carrier aircraft is stationary or moving at a low speed;

[0013] (2) The method of the present invention can avoid the problem that the aircraft needs to go around to the rear of the net during the in-air net-catch recovery when the aircraft and the net move towards each other, and it is easy to cause end overload saturation and recovery failure due to reverse net-catch during this process, and realizes all-round in-air net-catch recovery;

[0014] (3) The method of the present invention constrains the speed of the net-catch recovery to ensure the safety of the net structure, and the speed of the aircraft only converges to the expected speed magnitude during net-catch, thereby improving the efficiency of the recovery operation. Description of the Drawings

[0015] Figure 1 is a schematic diagram of the trajectory of in-air net-catch recovery of an aircraft in the prior art;

[0016] Figure 2 is a schematic flow diagram of a guidance method for in-air net-catch recovery of an aircraft according to the present invention;

[0017] Figure 3 is a schematic diagram of the navigation coordinate system and the line-of-sight angle in the present invention;

[0018] Figure 4 is a schematic structural diagram of a guidance system for in-air net-catch recovery of an aircraft according to the present invention;

[0019] Figure 5 is a schematic diagram of the trajectory of the net-catch flight path in Embodiment 1 of the present invention;

[0020] Figure 6 is a simulation result diagram of Embodiment 1 of the present invention;

[0021] Figure 7 is a simulation result diagram of Embodiment 2 of the present invention. Detailed Embodiments

[0022] The following elaborates on the preferred embodiments of the present invention in conjunction with the drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making the scope of protection of the present invention more clearly defined.

[0023] It should be noted that in this article, the term "including", "comprising" or any other variant thereof is intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements not only includes those elements but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the element.

[0024] During the in-air net-collision recovery process, the effective impact area S C can be expressed by the following formula:

[0025] S C = S * sinα, where S represents the net-catching area and α represents the collision angle between the aircraft and the net.

[0026] In the existing in-air net-collision recovery, to improve the recovery success rate and enable the aircraft to collide with the net from the front of the net, it is necessary to adjust the states of the aircraft and the carrier aircraft on the flight path before recovery, as Figure 1 shown. This net-collision flight path requires the carrier aircraft to frequently adjust its flight state, and the time available for recovery in the net-collision flight path is limited, and the recovery speed is slow, which is not conducive to the continuity and efficiency of in-air net-collision recovery.

[0027] Aiming at the problems existing in the prior art, the present invention provides a guidance method for in-air net-collision recovery of an aircraft. This method divides the net-collision flight path into p segments. When the aircraft is on the q-th segment of the flight path, a speed tracking method based on speed constraint and / or collision angle constraint is adopted to enable the aircraft to reach the p-th segment of the flight path at a relatively high speed. When the aircraft is on the p-th segment of the flight path, the aircraft performs a head-on tail-chasing net-collision recovery along a horizontal circular trajectory, where p is an integer greater than or equal to 2, and q represents at least one of 1 to p - 1. This method can achieve the continuity and efficiency of in-air net-collision recovery when the carrier aircraft and the net are stationary or moving at a low speed.

[0028] In a first aspect, the present invention provides a guidance method for in-air net-collision recovery of an aircraft. This method divides the net-collision flight path into p segments, and controls the aircraft to execute different control instructions on the p-th segment and the q-th segment of the flight path to achieve the net-collision recovery process of the aircraft, where p is an integer greater than or equal to 2, and q represents at least one of 1 to p - 1. For example, if p = 2, then q = 1, or if p = 4, then q = 1, 2, 3, 1 and 2, 1 and 3, 2 and 3, or 1 and 2 and 3.

[0029] In the implementation environment of the present invention, the carrier aircraft and the aircraft (including quadrotor aircraft or fixed-wing aircraft, etc.) are cooperative targets. The aircraft can receive differential GPS signals from the carrier aircraft or rely on its own optoelectronic pod, lidar, ultrasonic radar, etc. to sense and obtain the relative motion information of the aircraft and the capture net in real time, including relative position and relative velocity. In the present invention, the aircraft and the capture net are assumed to be an ideal particle model.

[0030] Specifically, as Figure 2 shown, the method mainly includes the following steps:

[0031] Step S101: Divide the net-collision flight path into p segments, and set the p-th segment of the flight path as a horizontal circular trajectory, where the p-th segment of the flight path is tangent to the initial velocity of the capture net and tangent to the (p - 1)-th segment of the flight path.

[0032] In the present invention, a virtual coordinate point (i.e., the starting point of the p-th segment of the flight path) is set to avoid direct collision when the aircraft and the capture net move towards each other (fly face to face) (i.e., fly around behind the capture net and pursue it into the net from the tail).

[0033] In the present invention, the p-th segment of the flight path is the last segment of the net-collision flight path. Therefore, it is necessary to make the control quantity input by the aircraft change less, and the entire flight trajectory is smoother. That is, at the end of the (p - 1)-th segment of the flight path, the aircraft and the capture net are at the same height. The aircraft moves on the horizontal plane in the p-th segment of the flight path. At this time, when the aircraft is on the circular trajectory, it only needs to keep the forward flight speed unchanged and the roll attitude angle unchanged, and finally quickly realize the aircraft's pursuit and entry into the net.

[0034] Among them, the starting point of the net-collision flight path, that is, the starting point of the first segment, is the position of the aircraft in the navigation coordinate system when the aircraft uses its own detection and navigation equipment (optoelectronic sphere, lidar, etc.) to accurately and stably identify the position of the capture net and can perform the next net-collision recovery task. The end point of each segment of the flight path is the starting point of the next segment of the flight path until the entire net-collision flight path. The p-th segment of the flight path is tangent to the (p - 1)-th segment of the flight path at the starting point of the p-th segment of the flight path.

[0035] Specifically, according to the relative position and relative velocity of the aircraft and the capture net (or carrier aircraft), design the trajectory of the p-th segment of the flight path, that is, a horizontal circular trajectory tangent to the line of sight with a certain radius in the horizontal direction.

[0036] It has been found through research that when the p-th segment of the flight path is set as a horizontal circular trajectory, when the forward flight speed of the aircraft remains unchanged, the smaller the radius, the greater the required roll direction acceleration (a y2 ). If it exceeds the overload capacity of the aircraft, it will lead to the failure of the recovery; the larger the radius, the larger the circular trajectory, the longer the flight time of the p-th segment of the flight path, the longer the net-collision recovery task cycle, and the lower the efficiency. It is preferably r > 10 m, and more preferably between 10 and 50 m.

[0037] Preferably, the trajectory of the p-th flight path is represented by Equation (1):

[0038]

[0039] where x2 and y2 respectively represent the position components of the p-th flight path in the X-axis direction and Y-axis direction of the aircraft in the navigation coordinate system;

[0040] v dx is the expected velocity component of the aircraft in the X-axis direction at the final net-hitting moment in the navigation coordinate system, which is a constant; preferably 4 - 15 m / s, more preferably 5 - 10 m / s, for example 8 m / s.

[0041] It has been found through research that when v dx is relatively small, the flight time for net-hitting recovery is relatively long; when v dx is relatively large, it will cause the aircraft to collide violently with the capture net, resulting in damage to the capture net and the aircraft.

[0042] As Figure 3 shown, the origin O n of the navigation coordinate system of the present invention coincides with the center of mass of the aircraft, O n X n axis is parallel to the local horizontal plane and points to the north in the geographical azimuth, O n Y n axis is also parallel to the local horizontal plane and points to the east in the geographical azimuth, O n Z n axis points downward from the origin and is perpendicular to the local horizontal plane, with the direction pointing to the center of the earth being positive.

[0043] r is the radius of the p-th flight path; t is the current guidance moment; t1 is the end moment of the (p - 1)-th flight path (i.e., the start moment of the p-th flight path);

[0044] θ0 represents the initial angle (in the p-th flight path) of the starting point of the p-th flight path in polar coordinates, and its magnitude is:

[0045] where x d and y d respectively represent the position components of the starting point of the p-th flight path in the X-axis direction and Y-axis direction in the navigation coordinate system.

[0046] When the net speed is relatively slow, the change in the starting point of the p-th flight path along the circular trajectory due to distance change is not considered; more preferably, the starting point position information of the p-th flight path is obtained through Equation (2):

[0047]

[0048] Wherein, m and n respectively represent the position components of the center of the p-th flight path in the X-axis direction and the Y-axis direction in the navigation coordinate system;

[0049] z d represents the position component of the starting point of the p-th flight path in the Z-axis direction in the navigation coordinate system;

[0050] z T (0) represents the initial position component of the fishing net in the Z-axis direction in the navigation coordinate system.

[0051] The center of the p-th flight path is on the line perpendicular to the direction of the fishing net speed at the initial moment; further, m and n are represented by Equation Three:

[0052]

[0053] Wherein, c = -1 / tan(v Ty (0) / v Tx (0)); specifically, when v Ty (0) = v Tx (0) = 0, c = 0; b = y T (0) - cx T (0);

[0054] x T (0), y T (0) respectively represent the initial position components of the fishing net in the X-axis direction and the Y-axis direction in the navigation coordinate system;

[0055] v Tx (0), v Ty (0) respectively represent the initial velocity components of the fishing net in the X-axis direction and the Y-axis direction in the navigation coordinate system.

[0056] Step S102, when at the q-th flight path, control the flight of the aircraft based on speed constraint and / or collision angle constraint, and when at the p-th flight path, control the aircraft to fly along the p-th flight path so that the aircraft chases and collides with the net for recovery.

[0057] Among them, if the aircraft collides with the net at a conventional speed, it is easy to damage the structure of the fishing net. Therefore, how to make the speed of the aircraft converge when colliding with the net is the key of the present invention.

[0058] It is found through research that when the aircraft is flying, the speed of the aircraft can be converged to the desired speed by speed constraint and / or collision angle constraint when colliding with the net.

[0059] In addition, in the collision flight path, if the speed constraint and / or collision angle constraint of the aircraft are imposed in the initial stage, it may lead to a reduction in the recovery efficiency. How to select a suitable stage is another key of the present invention.

[0060] Research has found that when q is preferably at least one of 1 to p-2 and p-1, or p-1, and more preferably q is p-1 or all of 1 to p-1, the aircraft can converge to the desired speed when colliding with the net and the recovery efficiency can be improved.

[0061] That is, for example, if p=2, then q=1; or if p=4, then q=3, 1 and 3, 2 and 3, or 1, 2 and 3, and q=3 or 1, 2 and 3 is more preferred.

[0062] Preferably, when based on the collision angle constraint, the guidance instruction of the aircraft is expressed by Formula 4:

[0063]

[0064] Among them, a y1 and a z1 They respectively represent the acceleration instructions of the aircraft in the Y-axis direction and the Z-axis direction in the navigation coordinate system during the qth route;

[0065] k y , k z represents the coefficient, that is, respectively represents a y1 and a z1 The coefficient corresponding to the acceleration, where k y , k z Directly affects a y1 and a z1 The size of k y , k z If it is too large, the aircraft will not be able to fly according to the planned trajectory; y , k z Too small will cause the acceleration command to be too large, exceeding the aircraft's own overload capacity. Preferably, -8≤k y <0, -8≤k z <0, more preferably, -5≤k y ≤-3, -5≤k z ≤-3.

[0066] d y d z represents a constant, which can suppress the oscillation of the acceleration command, where d y d z If the value is too small, the aircraft will have poor trajectory tracking ability and will not be able to fly according to the predetermined trajectory; y d z If the value is too large, the acceleration command oscillation suppression effect will be poor. Preferably, -5≤d y ≤0, -5≤d z ≤0, more preferably, -3≤d y ≤-1, -3≤d z ≤-1.

[0067] V represents the real-time speed value of the aircraft in the q-th flight path segment, with magnitude where v x1 , v y1 , v z1 respectively represent the velocity components of the aircraft in the X-axis direction, Y-axis direction, and Z-axis direction in the navigation coordinate system in the q-th flight path segment;

[0068] λ y , λ z respectively represent the pitch line-of-sight angle and the heading line-of-sight angle of the aircraft, and are obtained by the following formula:

[0069]

[0070] λ z ∈(-π, π)

[0071] λ vy , λ vz respectively represent the horizontal velocity angle and the heading velocity angle of the aircraft, and are obtained by the following formula:

[0072]

[0073] λ vy ∈(-π, π)

[0074] where, Δv x , Δv y , Δv z respectively represent the relative velocity components of the net and the aircraft along the X-axis direction, Y-axis direction, and Z-axis direction in the navigation coordinate system.

[0075] That is, Δv x = v Tx - v x1 , Δv y = v Ty - v y1 , Δv z = v Tz - v z1 ;

[0076] where, v Tx , v Ty , v Tz respectively represent the velocity components of the net in the X-axis direction, Y-axis direction, and Z-axis direction in the navigation coordinate system.

[0077] Preferably, when based on speed constraints, the guidance command of the aircraft is represented by Equation Five:

[0078] a x1 = k v [(kR ΔR + v dx ) - v x1 Formula Five

[0079] where a x1 represents the acceleration command of the aircraft in the X-axis direction in the navigation coordinate system in the q-th flight path segment;

[0080] k v represents a coefficient, that is, the coefficient of a x1 corresponding to the speed.

[0081] where k v directly affects the magnitude of a x1 ; k v has a value range greater than 0. When k v is too large, a x1 will exceed the overload capacity of the UAV. However, due to the attitude limit of the aircraft, the aircraft will only maintain flight at the maximum forward flight acceleration. Preferably, 0 < k v ≤ 3.

[0082] k R represents a coefficient, that is, the coefficient of the relative distance between the aircraft's desired speed and the net.

[0083] where, when the aircraft is farther from the net, the aircraft speed is greater; when the aircraft is closer to the net and in the p-th flight path segment, the aircraft speed is small, so that it can be ensured that the aircraft speed is small at the final moment of hitting the net and will not cause damage to the net structure; flying at a higher speed of the aircraft when it is farther from the net is beneficial to reducing the time required for the net-hitting recovery process. Therefore, 0 < k R ≤ 0.5. Preferably, the value is 0.02 ≤ k R ≤ 0.048.

[0084] ΔR represents the relative position value between the aircraft and the net in the q-th flight path segment, where x T , y T , z T represent the position components of the net in the X-axis direction, Y-axis direction, and Z-axis direction in the navigation coordinate system; x1, y1, z1 respectively represent the position components of the aircraft in the X-axis direction, Y-axis direction, and Z-axis direction in the navigation coordinate system under the q-th flight path segment.

[0085] Among them, when using the guidance command of Equation 4, only the control of the tail chase collision angle can be achieved, and the magnitude of the desired speed during net collision cannot be effectively controlled. When using the guidance command of Equation 5, the magnitude of the desired speed is changed, but the flight vehicle speed direction angle cannot be controlled. In the present invention, in order to enable the flight vehicle speed direction angle to be consistent with the net-catching speed direction angle, that is, to achieve tail chase net-catching, and to enable the flight vehicle to reach the desired speed, speed constraint and collision angle constraint need to be imposed on the flight vehicle.

[0086] Preferably, when based on speed constraint and collision angle constraint, in the q-th flight path segment, the guidance command of the flight vehicle is represented by Equation 6:

[0087]

[0088] Preferably, in the p-th flight path segment, the guidance command of the flight vehicle is represented by Equation 7:

[0089]

[0090] Wherein, a x2 、a y2 and a z2 respectively represent the acceleration commands of the flight vehicle in the X-axis direction, Y-axis direction and Z-axis direction in the navigation coordinate system in the p-th flight path segment.

[0091] In the present invention, the net collision recovery process is divided into p segments. The starting point of the p-th flight path segment is a virtual target point designed by the present invention according to Equation 2. In the q-th flight path segment, the flight vehicle starts the air net collision recovery task from the starting point of the first flight path segment. Through the guidance command of Equation 6, the flight vehicle reaches the starting point of the p-th flight path segment from the starting point of the q-th flight path segment, which not only satisfies the speed constraint and collision angle constraint required by the p-th flight path segment, but also can prevent the flight vehicle from colliding with the net in the reverse direction.

[0092] The p-th flight path segment is set as a horizontal circular trajectory. Through the guidance command of Equation 7, the flight vehicle can circle from the starting point of the p-th flight path segment along the horizontal circular trajectory to the rear of the net and enter the net. The forward flight speed of the flight vehicle in the p-th flight path segment remains unchanged, and the turning relies on the centripetal acceleration provided by the fixed roll angle of the flight vehicle. Therefore, the attitude control is simple, the trajectory is smoother and the net collision accuracy is high. At the same time, the speed of the flight vehicle in the p-th flight path segment is the same as the speed at the end of the q-th flight path segment, both of which satisfy the net collision speed constraint. Therefore, it is possible to prevent damage to the net-catching structure caused by too large a net collision speed, and full-directional rear-end tail chase can be achieved.

[0093] The method of the present invention can comprehensively achieve air net collision recovery, and improve the continuity and efficiency of air net collision recovery.

[0094] In a second aspect, the present invention provides a guidance system for air net collision recovery of a flight vehicle. Specifically, as Figure 4As shown, the system mainly includes the following modules:

[0095] A route division module 401, which is used to divide the net-collision route into p segments, and set the p-th segment of the route as a horizontal circular trajectory, where the p-th segment of the route is tangent to the initial speed of the net-catching, and is tangent to the (p-1)-th segment of the route;

[0096] An execution module 402, which is used to control the flight of the aircraft based on speed constraints and / or collision angle constraints when the aircraft is on the q-th segment of the route, and control the aircraft to fly along the p-th segment of the route when the aircraft is on the p-th segment of the route, so that the aircraft can pursue and collide with the net for recovery.

[0097] The guidance system for aircraft air net-collision recovery provided by the present invention can be used to execute a guidance method for aircraft air net-collision recovery described in the first aspect above. Its implementation principle and technical effects are similar, and will not be elaborated here.

[0098] Preferably, each module in the guidance system for aircraft air net-collision recovery of the present invention can be directly in hardware, in a software module executed by a processor, or in a combination of both.

[0099] The software module can reside in a RAM memory, a flash memory, a ROM memory, an EPROM memory, an EEPROM memory, a register, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. The exemplary storage medium is coupled to the processor so that the processor can read information from and write information to the storage medium.

[0100] The processor can be a Central Processing Unit (CPU), or it can be other general-purpose processors, Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic, discrete hardware components, or any combination thereof. The general-purpose processor can be a microprocessor, but in an alternative, the processor can be any conventional processor, controller, microcontroller, or state machine. The processor can also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in combination with a DSP core, or any other such configuration. In an alternative, the storage medium can be integrated with the processor. The processor and the storage medium can reside in an ASIC. The ASIC can reside in a user terminal. In an alternative, the processor and the storage medium can reside in the user terminal as discrete components.

[0101] Embodiment

[0102] Example 1

[0103] The capture net A is stationary at (300, 40, 50) m in the navigation coordinate system, and the capture net A faces away from the negative X-axis direction; the aircraft is at point O (0, 0, 0), and point O is the starting point of the net-collision flight path, with an initial velocity v x1 (0) = 12 m / s, v y1 (0) = 5 m / s, v z1 (0) = 0 m / s.

[0104] The net-collision flight path is divided into two segments, namely the first segment of the flight path OC and the second segment of the flight path CA, as Figure 5 shown. The second segment of the flight path is a horizontal circular trajectory with a radius r = 40 m centered at point B on the perpendicular to the velocity of the capture net A, and the point C where the ray (the first segment of the flight path) drawn from point O is tangent to the second segment of the flight path is the starting point of the second segment of the flight path.

[0105] That is, the trajectory of the second segment of the flight path is represented by Equation 1:

[0106]

[0107] where x2 and y2 respectively represent the position components of the aircraft in the X-axis direction and the Y-axis direction in the navigation coordinate system in the second segment of the flight path; v dx= 8 m / s; t is the current guidance time; t1 is the end time of the first flight path;

[0108]

[0109] Among them, the coordinates of point C are (x d , y d ), where x d , y d are represented by Equation 2:

[0110]

[0111] Add velocity constraints for two tangent flight paths at point C. The velocity constraints at point C (v xdC , v ydC ) need to satisfy:

[0112]

[0113] Among them, the coordinates of point B are (m, n), where m and n are represented by Equation 3:

[0114]

[0115] Among them, c = -1 / tan(v Ty (0) / v Tx (0)), b = y T (0) - cx T (0);

[0116] x T (0) = 300 m, y T (0) = 40 m; v Tx (0) = 0, v Ty (0) = 0, c = 0

[0117] During the first flight path, control the flight of the aircraft based on velocity constraints and collision angle constraints.

[0118] Specifically, in the first flight path, the guidance command of the aircraft is represented by Equation 6:

[0119]

[0120] Among them, a x1 , a y1 and a z1 respectively represent the acceleration commands of the aircraft in the X-axis direction, Y-axis direction, and Z-axis direction in the navigation coordinate system during the first flight path;

[0121] k v = 1.5, k y = -3, k z= -3, k R = 0.045, d y = -2, d z = -2;

[0122] ΔR represents the relative position value between the aircraft and the capture net in the first flight path, where x T = 300 m, y T = 40 m, z T = 50 m; x1, y1, z1 respectively represent the position components of the aircraft in the X-axis direction, Y-axis direction, and Z-axis direction in the navigation coordinate system under the first flight path;

[0123] V represents the real-time speed value of the aircraft in the first flight path, where v x1 , v y1 , v z1 respectively represent the speed components of the aircraft in the X-axis direction, Y-axis direction, and Z-axis direction in the navigation coordinate system in the first flight path;

[0124] λ y , λ z respectively represent the pitch line-of-sight angle and the heading line-of-sight angle of the aircraft, and are obtained by the following formula:

[0125]

[0126] λ z ∈(-π, π)

[0127] λ vy , λ vz respectively represent the horizontal speed angle and the heading speed angle of the aircraft, and are obtained by the following formula:

[0128]

[0129] λ vy ∈(-π, π)

[0130] where, Δv x , Δv y , Δv z respectively represent the relative speed components of the capture net and the aircraft along the X-axis direction, Y-axis direction, and Z-axis direction in the navigation coordinate system, that is, Δv x = v Tx - v x1 , Δv y = v Ty - v y1 , Δv z = v Tz - v z1;

[0131] Among them, v Tx = 0; v Ty = 0; v Tz = 0;

[0132] In the second flight path, the guidance command of the aircraft is expressed by Equation VII:

[0133]

[0134] Among them, a x2 , a y2 and a z2 respectively represent the acceleration commands of the aircraft in the X-axis direction, Y-axis direction, and Z-axis direction in the navigation coordinate system in the second flight path.

[0135] The specific simulation results are as shown in Figure 6 a) - c). Figure 6 a) is the schematic diagram of the three-dimensional trajectory of net capture and recovery; Figure 6 b) is the schematic diagram of the speed curve of the aircraft; Figure 6 c) is the schematic diagram of the acceleration curve of the aircraft.

[0136] It can be seen from Figure 6 that the aircraft takes 26.2 s to reach the starting point C of the second flight path from the net capture flight path point O, and then bypasses to the back of the net along the CA section of the second flight path and hits the net, realizing in-air net capture and recovery.

[0137] Example 2

[0138] The net A is at (250, 40, 20) m in the navigation coordinate system, and the speed of the net A is v Tx (0) = 4 m / s, v Ty (0) = 3 m / s, v Tz (0) = 0 m / s; the aircraft is at point O(0, 0, 0), and point O is the starting point of the net-hitting flight path, with an initial velocity v x1 (0) = 12 m / s, v y1 (0) = 5 m / s, v z1 (0) = 0 m / s.

[0139] An experimental process similar to that of Embodiment 1, with the only difference being that in the first flight path, the flight of the aircraft is controlled based on the collision angle constraint.

[0140] Among them, in the first flight path, the guidance command of the aircraft is expressed by Equation IV:

[0141]

[0142] Among them, a y1 and az1 respectively represent the acceleration commands of the aircraft in the Y-axis direction and Z-axis direction in the navigation coordinate system during the first flight path segment; k y =-3, k z =-3, d y =-2, d z =-2;

[0143] V represents the real-time speed value of the aircraft during the first flight path segment, where v x1 , v y1 , v z1 respectively represent the speed components of the aircraft in the X-axis direction, Y-axis direction, and Z-axis direction in the navigation coordinate system during the first flight path segment;

[0144] λ y , λ z respectively represent the pitch line-of-sight angle and the heading line-of-sight angle, obtained by the following formula:

[0145]

[0146] λ z ∈(-π,π)

[0147] λ vy , λ vz respectively represent the horizontal speed angle and the heading speed angle of the aircraft, obtained by the following formula:

[0148]

[0149] λ vy ∈(-π,π)

[0150] where, Δv x , Δv y , Δv z respectively represent the relative speed components of the net and the aircraft along the X-axis direction, Y-axis direction, and Z-axis direction in the navigation coordinate system, that is, Δv x =v Tx -v x1 , Δv y =v Ty -v y1 , Δv z =v Tz -v z1 ;

[0151] where, v Tx , v Ty , v Tz respectively represent the speed components of the net in the X-axis direction, Y-axis direction, and Z-axis direction in the navigation coordinate system.

[0152] The specific simulation results are shown in Figure 7 a) to e). Figure 7 a) is a schematic diagram of the change in the relative distance between the aircraft and the capture net; Figure 7 b) is a schematic diagram of the three-dimensional trajectory of the capture net recovery; Figure 7 c) is a schematic diagram of the speed curve of the aircraft; Figure 7 d) is a schematic diagram of the acceleration curve of the aircraft; Figure 7 e) is a schematic diagram of the change in the horizontal course speed angle between the aircraft and the capture net.

[0153] From Figure 7 a), it can be seen that after 31.5 s of flight, the relative distance between the aircraft and the capture net converges to 0, and the three-dimensional flight path trajectory is as shown in Figure 7 b). From Figure 7 c) and 7e), it can be seen that on the horizontal plane, the speed direction angle of the end aircraft is the same as that of the capture net, that is, tail pursuit is achieved, and the acceleration curve is as shown in Figure 7 d).

[0154] The present invention has been described in detail above in combination with specific embodiments and exemplary examples, but these descriptions should not be construed as limiting the present invention. Those skilled in the art understand that without departing from the spirit and scope of the present invention, various equivalent substitutions, modifications or improvements can be made to the technical solutions and their implementation manners of the present invention, and these all fall within the scope of the present invention.

Claims

1. A guidance method for the aerial net - collision recovery of an aircraft, characterized in that, Divide the net - hitting flight path into p segments, and control the aircraft to execute different control instructions on the p - th segment and the q - th segment of the flight path to achieve the net - hitting recovery process of the aircraft, where p is an integer greater than or equal to 2, and q represents at least one of 1 to p - 1. It includes the following steps: Step S101: Divide the net - hitting flight path into p segments, and set the p - th segment of the flight path as a horizontal circular trajectory, where the p - th segment of the flight path is tangent to the initial velocity of the net - catching device and tangent to the (p - 1) - th segment of the flight path. Step S102: When on the q - th segment of the flight path, control the flight of the aircraft based on velocity constraints and / or collision - angle constraints; and when on the p - th segment of the flight path, control the aircraft to fly along the p - th segment of the flight path so that the aircraft catches up with the net for recovery by tail - chasing. In step S101, the trajectory of the p - th segment of the flight path is represented by Equation (1): Where x2 and y2 respectively represent the p - th segment of the flight path, and in the navigation coordinate system, they are the position components of the aircraft in the X - axis direction and the Y - axis direction. v dx Is the final netting moment. In the navigation coordinate system, it is the expected velocity component of the aircraft in the X-axis direction; r is the radius of the p - th segment of the flight path; t is the current guidance time; t1 is the end time of the (p - 1) - th segment of the flight path. m and n respectively represent that in the navigation coordinate system, they are the position components of the center of the p - th segment of the flight path in the X - axis direction and the Y - axis direction. θ0 represents the initial angle of the starting point of the p - th segment of the flight path in polar coordinates. where x d and y d respectively represent the position components of the starting point of the p-th flight path in the X-axis direction and the Y-axis direction in the navigation coordinate system.

2. The guidance method for the aerial net - collision recovery of an aircraft according to claim 1, characterized in that, x d 、y d Obtained by Equation 2: Among them, z d represents the position component of the starting point of the p-th flight path in the Z-axis direction in the navigation coordinate system; z T (0) represents the initial position component of the net in the Z-axis direction in the navigation coordinate system.

3. The guidance method for the aerial net - collision recovery of an aircraft according to claim 2, characterized in that, m and n are represented by Equation (3): where c = -1 / tan(v Ty (0) / v Tx (0)), b = y T (0) - cx T (0); x T (0), y T (0) respectively represent the initial position components of the net in the X-axis direction and the Y-axis direction in the navigation coordinate system; v Tx (0), v Ty (0) represent the initial velocity components of the net in the X-axis direction and the Y-axis direction in the navigation coordinate system, respectively.

4. The guidance method for the aerial net - collision recovery of an aircraft according to claim 1, characterized in that, In step S102, when based on the collision - angle constraint, the guidance instruction of the aircraft is represented by Equation (4): Among them, a y1 and a z1 respectively represent the acceleration commands of the aircraft in the Y-axis direction and Z-axis direction in the navigation coordinate system in the q-th flight path segment; k y and k z represent coefficients; d y and d z represent constants; V represents the real-time speed value of the aircraft in the q-th flight path segment. Among them, v x1 and v y1 and v z1 respectively represent the velocity components of the aircraft in the X-axis direction, Y-axis direction and Z-axis direction in the navigation coordinate system in the q-th flight path segment; λ y and λ z respectively represent the pitch line-of-sight angle and the heading line-of-sight angle of the aircraft; λ vy and λ vz respectively represent the horizontal speed angle and the heading speed angle of the aircraft.

5. The guidance method for the aerial net - collision recovery of an aircraft according to claim 4, characterized in that, -8 ≤ k y <0, -8 ≤ k z <0; -5 ≤ d y ≤ 0, -5 ≤ d z ≤ 0.

6. The guidance method for the aerial net - collision recovery of an aircraft according to claim 1, characterized in that, In step S102, when based on the velocity constraint, the guidance instruction of the aircraft is represented by Equation (5): a x1 = k v [(k R ΔR + v dx ) - v x1 Equation Five Among them, a x1 represents the acceleration command of the aircraft in the X-axis direction in the navigation coordinate system in the q-th flight path segment; k v , k R represent coefficients; ΔR represents the relative position value between the aircraft and the net in the q-th flight path segment, where x T , y T , z T represent the position components of the net in the X-axis direction, Y-axis direction, and Z-axis direction in the navigation coordinate system; x1, y1, z1 respectively represent the position components of the aircraft in the X-axis direction, Y-axis direction, and Z-axis direction in the navigation coordinate system in the q-th flight path segment; v dx is the expected velocity component of the aircraft in the X-axis direction in the navigation coordinate system at the final net impact moment; v x1 represents the velocity component of the aircraft in the X-axis direction in the navigation coordinate system in the q-th flight path segment.

7. The guidance method for the aerial net - collision recovery of an aircraft according to claim 1, characterized in that,In step S102, on the p - th segment of the flight path, the guidance instruction of the aircraft is represented by Equation (7): Among them, a x2 , a y2 and a z2 respectively represent the acceleration commands of the aircraft in the X-axis direction, Y-axis direction, and Z-axis direction in the navigation coordinate system for the p-th flight path segment.

8. A guidance system for implementing the guidance method of aerial net-capturing recovery of an aircraft according to any one of claims 1 to 7, characterized in that, It includes: A flight - path division module, which is used to divide the net - hitting flight path into p segments and set the p - th segment of the flight path as a horizontal circular trajectory, where the p - th segment of the flight path is tangent to the initial velocity of the net - catching device and tangent to the (p - 1) - th segment of the flight path. An execution module, which is used to control the flight of the aircraft based on velocity constraints and / or collision - angle constraints when on the q - th segment of the flight path, and control the aircraft to fly along the p - th segment of the flight path so that the aircraft catches up with the net for recovery by tail - chasing when on the p - th segment of the flight path.

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