Aerial low-speed target attack method for fixed-wing unmanned aerial vehicle

Abstract

The invention relates to an air low-speed target attack method for a fixed-wing unmanned aerial vehicle, and the method comprises the steps: taking an unmanned aerial vehicle to find a target as a starting point, and enabling an air target attack process to be a posture adjustment stage, a pre-attack stage and an evacuation stage, and the posture adjustment stage is mainly used for carrying out the coarse alignment preparation of the pre-attack stage; the pre-attack stage is the core of the attack method, and automatic alignment and attack of the unmanned aerial vehicle are realized; and ensuring the flight safety of the unmanned aerial vehicle in the evacuation stage. According to the method, the attack process is refined, the pre-attack accurate alignment method is defined, the unmanned aerial vehicle attitude control law is designed, rapid maneuvering can be performed after a seeker finds a target, the unmanned aerial vehicle is guided to approach the target, further accurate alignment is completed based on unmanned aerial vehicle attitude control, automatic attack triggering conditions are perfected, attack timeliness is ensured, and the method is suitable for popularization and application. Effective attacks are carried out on air low-speed targets, and the unmanned aerial vehicle attack precision is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of unmanned aerial vehicles, and relates to a method for attacking low-speed aerial targets by a fixed-wing unmanned aerial vehicle. Background Art

[0002] With the increasingly wide application of unmanned aerial vehicles in modern warfare and the increasingly diverse combat missions, especially when both sides of the combat use unmanned aerial vehicles as the offensive units and carry out anti-unmanned aerial vehicle operations against each other. The existing effective anti-unmanned aerial vehicle strategies mainly include unmanned aerial vehicle early warning and monitoring, electronic interference, laser interception, missile and artillery attacks, etc. The above means all need to consider the ownership of air superiority, deployment environment, deployment quantity, deployment cost, etc. And in air combat, ground missile attacks have high accuracy, but when installed on unmanned aerial vehicles, the modification difficulty is large, the requirements for the flight performance of unmanned aerial vehicles are high, and the cost is high. Therefore, considering loading gun equipment on unmanned aerial vehicles, but rotor unmanned aerial vehicles are limited by factors such as flight altitude, flight speed, endurance, and payload. Based on fixed-wing unmanned aerial vehicles, the present invention elaborates on the method for attacking aerial targets.

[0003] For aerial targets, considering that in the early stage of unmanned aerial vehicle combat, it is mainly for reconnaissance and consumption, and small and medium-sized low-cost unmanned aerial vehicles are mostly used to approach forward. At present, in the research on the weapon mounting of small and medium-sized unmanned aerial vehicles, there have already appeared designs for mounting light weapons such as rifles to attack ground targets. And when dealing with low-speed aerial targets (true airspeed ≤ 100 km / h), in order to ensure the attack accuracy, new requirements are put forward for the specific attack process, pre-attack method, and attitude control strategy during the operation of unmanned aerial vehicles.

[0004] Therefore, in order to deal with the reconnaissance of our defense deployment, the breakthrough of our frontline defense, and the consumption of our vital forces by the enemy's small and medium-sized low-speed low-cost unmanned aerial vehicles, with the goal of effective attack, it is necessary to further improve the attack process, pre-attack method, and unmanned aerial vehicle attitude control law for air-to-air combat. Summary of the Invention

[0005] Technical Problems to be Solved

[0006] In order to avoid the deficiencies of the prior art, the present invention proposes a method for attacking low-speed aerial targets by a fixed-wing unmanned aerial vehicle, which can effectively defend against means such as reconnaissance, surveillance, interference, and self-destruction attacks of low-speed aerial targets (true airspeed ≤ 100 km / h), refine the combat process of unmanned aerial vehicles, clarify the pre-attack strategy, design the unmanned aerial vehicle attitude control strategy, reduce the unmanned aerial vehicle attitude adjustment time and flight distance, improve the automatic attack trigger conditions, ensure the attack timeliness, and improve the attack accuracy of the gun-equipped fixed-wing unmanned aerial vehicle against air targets.

[0007] Technical Solutions

[0008] A method for a fixed-wing unmanned aerial vehicle to attack low-speed targets in the air, characterized in that: starting from the unmanned aerial vehicle discovering the target, the attack process includes: attitude adjustment stage, pre-attack stage, attack stage, and evacuation stage; the process steps are as follows:

[0009] Attitude adjustment stage: After the unmanned aerial vehicle locks on the target, it adjusts its own flight altitude H to be equal to the target altitude H T with the target altitude H as the standard, so that the unmanned aerial vehicle and the target are on the same horizontal line; T At the same time, adjust the nose direction of the unmanned aerial vehicle to point to the target, so that the unmanned aerial vehicle and the target form a tail-chasing or head-on relationship to complete rough alignment;

[0010] Pre-attack stage: The unmanned aerial vehicle approaches the target in a tail-chasing or head-on manner. After entering the range, quickly adjust the pitch angle θ and yaw angle ψ of the unmanned aerial vehicle to accurately aim the installed weapon at the target, and automatically fire after meeting the attack conditions;

[0011] In the tracking control of the flight attitude of the unmanned aerial vehicle in the pre-attack stage, the longitudinal control of the unmanned aerial vehicle is pitch tracking control, so that the azimuth deviation angle ψ

[0012] and the pitch deviation angle θ e enter the range determined by the attack judgment conditions, and the engine maintains speed control; e The attack conditions are: (Ltan(θ

[0013] )) e +(Ltan(ψ 2 )) e ≤(R 2 +R T +R B ) 2 , where L is the distance between the aircraft and the target, θ e is the pitch deviation angle between the unmanned aerial vehicle and the target, ψ e is the azimuth deviation angle between the unmanned aerial vehicle and the target, R T is the radius of the projected circle of the side of the target that can withstand the attack, and R B is the ammunition dispersion radius at the current distance between the aircraft and the target;

[0014] Attack stage: Starting from the moment of firing, the end of this stage is to transfer to the evacuation stage after firing all the ammunition;

[0015] Evacuation stage: After the attack is completed, the unmanned aerial vehicle quickly turns to avoid the area where the target is located;

[0016] During the rapid turning control, the unmanned aerial vehicle implements longitudinal control and lateral and directional control;

[0017] The longitudinal control includes altitude control and pitch tracking control;

[0018] The lateral and directional control includes azimuth tracking control and roll control;

[0019] The altitude control uses the target flight altitude H T as the given altitude H for the UAV flight altitude g , and based on the current flight altitude H of the UAV and the given altitude H of the flight altitude g calculate the given pitch angle θ of the UAV g ;

[0020] The pitch tracking control is based on the pitch deviation angle θ e , calculate the given pitch angle θ of the UAV g ; Then, using the pitch angle θ of the UAV, the given pitch angle θ g , the pitch angular velocity q of the UAV, and the roll angle of the UAV calculate the given elevator deflection δ e , so that the UAV tracks this θ g ;

[0021] The azimuth tracking control is based on the azimuth deviation angle ψ e , calculate the given roll angle of the UAV

[0022] The roll control uses the maximum roll angle of the UAV calculate the given roll angle of the UAV Then, using the roll angle of the UAV the given roll angle of the UAV the roll angular velocity p of the UAV, calculate the given aileron deflection δ a , so that the UAV tracks this

[0023] When adjusting its own flight altitude H with the target altitude H T as the standard, the longitudinal control of the UAV is altitude control, and the lateral-directional control is azimuth tracking control. By adjusting the flight altitude H and the yaw angle ψ of the UAV, make the altitude deviation ΔH and the azimuth deviation angle ψ e controlled to 0, and the engine maintains speed control; The target altitude H T and the relationship between its own flight altitude H is: H T = H + Lsin(θ G ), where: L is the distance between the aircraft and the target, θ G is the line-of-sight elevation angle θ G .

[0024] The attack conditions are satisfied with three items: 1. Entering the range distance: When the distance L between the aircraft and the target is less than or equal to 1.2 times the weapon standard range L s , that is, L ≤ 1.2L s , it is considered that the target enters the attack range, and the attack mission is carried out within this distance; 2. Azimuth locking: According to the distance L between the aircraft and the target, the line-of-sight azimuth angle ψG and the yaw angle ψ of the UAV and the weapon installation azimuth angle ψ 0 , calculate the UAV azimuth angle control range required to hit the target. When the azimuth deviation angle ψ between the UAV and the target e meets certain conditions, it is determined that the azimuth lock is successful; 3. Pitch lock: According to the aircraft-target distance L, the line-of-sight elevation angle θ G , the pitch angle θ of the UAV, and the weapon installation elevation angle θ 0 , calculate the UAV elevation angle control range required to hit the target. When the pitch deviation angle between the UAV and the target meets the condition θ e , it is determined that the pitch lock is successful.

[0025] The azimuth deviation angle ψ e meets certain conditions: ψ e = ψ G - ψ - ψ 0 , where: ψ G is the line-of-sight azimuth angle, ψ is the yaw angle of the UAV, and ψ 0 is the weapon installation azimuth angle.

[0026] The pitch deviation angle meets the condition θ e : θ e = θ G - θ - θ 0 , where: θ G is the line-of-sight elevation angle, θ is the pitch angle of the UAV, and θ 0 is the weapon installation elevation angle.

[0027] The ammunition dispersion radius at the current aircraft-target distance where: R s is the ammunition dispersion radius under the weapon standard range, L s is the weapon standard range, and L is the aircraft-target distance.

[0028] The evacuation condition for entering the evacuation stage is that when the aircraft-target distance L reaches the minimum roll distance L min of the evacuation condition, that is, L ≤ L min , stop the attack and enter the evacuation stage.

[0029] The elevator given deflection δ e to make the UAV track this θ g is calculated as:

[0030]

[0031] where: k θ , k q , k θi , is the elevator control parameter; k h , khi is the pitch angle command control parameter; k θ , k θi , k θd are the pitch tracking control parameters.

[0032] The given aileron deflection δ a of the UAV enables the UAV to track this is calculated as:

[0033]

[0034] Where: k p , are the aileron control parameters; k ψ , k ψi , k ψd are the roll angle command control parameters.

[0035] A computer program product, characterized by comprising computer-executable instructions, which are used to implement the method for a fixed-wing UAV to attack a low-speed target in the air according to claims 1 to 9 when executed.

[0036] Beneficial effects

[0037] A method for a fixed-wing UAV to attack a low-speed target in the air proposed by the present invention, firstly, starting from the UAV discovering the target, the process of attacking an air target is: the attitude adjustment stage, the pre-attack stage, and the evacuation stage, where the attitude adjustment stage mainly prepares for rough alignment for the pre-attack stage; the pre-attack stage is the core of this attack method, realizing automatic alignment and attack of the UAV; the evacuation stage ensures the flight safety of the UAV. The present invention is based on a conventional fixed-wing UAV, equipped with a gun. When the target is discovered, the UAV automatically enters the attack process, and adjusts the attitude of the UAV to try to align with the target during this period. After determining that the attack conditions are met, it automatically fires at the target.

[0038] The beneficial effects of the present invention are:

[0039] (1) It is beneficial to clarify the attack process of a fixed-wing UAV with a gun attacking an air target;

[0040] (2) It is beneficial to refine the functions of each stage of the attack process;

[0041] (3) It is beneficial for the UAV to quickly maneuver and approach the target;

[0042] (4) It is beneficial to clarify the specific alignment method and attack determination conditions in the pre-attack stage;

[0043] (5) It is beneficial to improve the attitude control law during the attack process;

[0044] (6) It is beneficial to improve the attack accuracy against low-speed aerial targets;

[0045] (7) It is beneficial to improve the reliability and safety during the attack of the unmanned aerial vehicle. Description of the Drawings

[0046] Figure 1 It is a schematic diagram of the attack phase of the unmanned aerial vehicle

[0047] Figure 2 It is a flow chart of the attack of the unmanned aerial vehicle Detailed Implementation Manner

[0048] Now, in combination with the embodiments and the drawings, the present invention will be further described:

[0049] The core idea of the present invention is: aiming at the task requirements of the attack accuracy of the unmanned aerial vehicle in air combat, the present invention proposes an automatic attack process, a pre-attack strategy and a corresponding attitude control method based on the flight performance of the unmanned aerial vehicle, so that the unmanned aerial vehicle can quickly adjust its attitude when performing a tail chase or head-on attack on a low-speed aerial target, and perform an automatic attack after alignment, ensuring the timeliness of the unmanned aerial vehicle's air combat and improving the attack accuracy of the unmanned aerial vehicle.

[0050] For the convenience of understanding the technical solution, the coordinate system and symbols related to the present invention are described as follows.

[0051] a) Ground coordinate axis system ONED

[0052] The flight distance of the unmanned aerial vehicle of the present invention is relatively short, and the curvature of the earth is ignored. The ground coordinate axis system is used as the inertial coordinate system. The origin O is an arbitrary point on the ground. The ON axis points due north in the horizontal plane, the OD axis is perpendicular to the horizontal plane and points towards the center of the earth, and the OE axis points due east in the horizontal plane.

[0053] b) Body coordinate axis system Oxyz

[0054] The origin O is taken at the center of mass of the unmanned aerial vehicle. The coordinate system is fixed to the unmanned aerial vehicle. The Ox is in the symmetry plane of the unmanned aerial vehicle and is parallel to the design axis and points towards the nose. The Oy is perpendicular to the symmetry plane of the unmanned aerial vehicle and points to the right side of the unmanned aerial vehicle. The Oz is in the symmetry plane of the unmanned aerial vehicle and is perpendicular to the Ox axis and points downward along the fuselage.

[0055] c) Main symbols and polarities

[0056] 1) Symbols related to the unmanned aerial vehicle body

[0057] H is the current flight altitude of the unmanned aerial vehicle, with the unit of meter (m), and the upward direction is positive;

[0058] H g is the given value of the current flight altitude of the unmanned aerial vehicle, with the unit of meter (m), and the upward direction is positive;

[0059] is the roll angle of the UAV, in degrees (°), which is the angle between the body axis Oz and the vertical plane passing through the body axis Ox. It is positive when the UAV rolls to the right;

[0060] is the given value of the current roll angle of the UAV, in degrees (°), with a right roll being positive;

[0061] is the maximum roll angle of the UAV, in degrees (°), with a right roll being positive;

[0062] ψ is the yaw angle of the UAV, in degrees (°), which is the angle between the projection of the UAV's Ox axis on the horizontal plane and the ON axis. A right yaw of the nose is positive;

[0063] θ is the pitch angle of the UAV, in degrees (°), which is the angle between the UAV's Ox axis and the horizontal plane. A nose-up is positive;

[0064] θ g is the given value of the current pitch angle of the UAV, in degrees (°), with a nose-up being positive;

[0065] p is the roll angular velocity of the UAV, in degrees per second (° / s), which is consistent with the body axis Ox;

[0066] q is the pitch angular velocity of the UAV, in degrees per second (° / s), which is consistent with the body axis Oy;

[0067] δ e is the given elevator deflection of the UAV, in degrees (°), with a downward deflection of the trailing edge of the elevator surface being positive;

[0068] δ a is the given aileron deflection of the UAV, in degrees (°), with an upward deflection of the trailing edge of the left aileron surface and a downward deflection of the trailing edge of the right aileron surface being positive;

[0069] L min is the minimum roll distance of the UAV, in meters (m).

[0070] 2) Target-related symbols

[0071] H T is the flight altitude of the target, in meters (m), with upward being positive;

[0072] R T is the radius of the target, in meters (m).

[0073] 3) Seeker-related symbols

[0074] θ G is the elevation angle of the line of sight, in degrees (°), which is the angle between the line of sight direction in the ground coordinate system and the horizontal plane. A line of sight pointing above the horizontal plane is positive;

[0075] ψ Gis the line-of-sight azimuth angle, in degrees (°), which is the angle between the line-of-sight direction and the longitudinal plane in the ground coordinate system, with the right side being positive;

[0076] L is the distance between the UAV and the target, i.e., the aircraft-target distance, in meters (m).

[0077] 4) Symbols related to weapon installation

[0078] ψ 0 is the weapon installation azimuth angle, in degrees (°), which is the angle between the weapon muzzle direction and the Oxz plane of the UAV body coordinate system, with right deviation being positive;

[0079] θ 0 is the weapon installation elevation angle, in degrees (°), which is the angle between the weapon muzzle direction and the Oxy plane of the UAV body coordinate system, with upward deviation being positive;

[0080] R B is the ammunition dispersion radius at the current aircraft-target distance, in meters (m);

[0081] R s is the ammunition dispersion radius under the standard range of the weapon, in meters (m);

[0082] L s is the standard range of the weapon, in meters (m).

[0083] 5) Symbols for the relative relationship between the UAV and the target

[0084] ψ e is the azimuth deviation angle, in degrees (°);

[0085] θ e is the pitch deviation angle, in degrees (°);

[0086] ΔH is the altitude difference between the UAV and the target during flight, in meters (m), with the target being higher than the UAV being positive.

[0087] Based on the flight performance of existing medium and small UAVs, the present invention uses a gun with a built-in fire control system as the attack weapon. After the seeker discovers the target, based on the target flight altitude H T quickly adjusts the UAV flight altitude H to reduce the altitude difference ΔH between the two, with a smaller line-of-sight elevation angle θ G to lock the target. However, in this state, it is still not possible to ensure that the muzzle is exactly aimed at the target. Therefore, it is also necessary to design a pre-attack strategy and control law to accurately aim the muzzle at the target and automatically fire at an appropriate distance. After firing, whether or not the target is hit, to ensure the flight safety of the UAV and to re-enter the attack state, it is necessary to control the UAV to quickly evacuate the position where the target is located. After the UAV evacuates near the target, it continues to search for the next target and re-enters the attack process.

[0088] The following describes the exemplary embodiments of the present invention in detail based on the technical solutions and with reference to the accompanying drawings. This example takes a low-speed and uniform straight-line flying unmanned aerial vehicle (true airspeed ≤ 100 km / h) in the air as the attack target to illustrate the feasibility and effectiveness of the present invention, and at the same time enables those skilled in the relevant art to understand the present invention more thoroughly, but should not be limited to the uniformly moving straight-line target.

[0089] As Figure 2 shown in the schematic diagram of the UAV attack process, starting from the UAV discovering the target, each stage in the process of pursuing the target is detailedly divided: the attitude adjustment stage, the pre-attack stage, the attack stage, and the evacuation stage, which are specifically described as follows.

[0090] The specific attack process is as Figure 2 shown.

[0091] a) Attitude adjustment stage

[0092] After the UAV searches, discovers, and successfully locks the target, it automatically enters the attack process. The UAV quickly adjusts its own flight altitude H T with reference to the target altitude H, and at the same time adjusts the nose direction of the UAV to point to the target, so that the UAV forms a tail-chasing or head-on relationship with the target to complete the rough alignment. When the distance between the UAV and the target enters the range, it enters the pre-attack stage.

[0093] In this stage, the longitudinal control of the UAV is altitude control, and the lateral and longitudinal control is azimuth tracking control. By adjusting the flight altitude H and yaw angle ψ of the UAV, the altitude deviation ΔH and azimuth deviation angle ψ e are controlled to 0, and the engine maintains speed control.

[0094] Among them, the target flight altitude H T can be calculated based on the current flight altitude H of the UAV, the distance L between the UAV and the target, and the line-of-sight elevation angle θ G as follows:

[0095] H T = H + Lsin(θ G )(1)

[0096] In the embodiment: During the air cruise search stage of the gun-carrying fixed-wing UAV, a uniformly moving straight-line target is found in front, and its true airspeed is less than that of the UAV. The seeker of the UAV quickly enters the target locking state from the scanning state and successfully captures the target. The UAV state enters the guidance stage of the attack process, and based on the current flight altitude H of the UAV, the distance L between the UAV and the target, the line-of-sight elevation angle θ G and formula (1), the target flight altitude H T is calculated. The UAV tracks the target altitude H T with an altitude control strategy; at the same time, the UAV tracks the azimuth deviation angle ψ e, so as to control the UAV to quickly maneuver and adjust its flight attitude and approach the target, achieving rough alignment of the UAV and making the altitude deviation ΔH and azimuth deviation angle ψ e controlled to 0.

[0097] b) Pre-attack phase

[0098] The UAV continues to approach the target in a tail-chasing or head-on manner. After entering the range, it quickly adjusts the pitch angle θ and yaw angle ψ of the UAV to accurately aim the installed weapon at the target and automatically fires after meeting the attack conditions. For the convenience of explanation, the side of the target receiving the attack is projected as a circle with a radius of R T The UAV attack determination conditions include three items, and ammunition will be automatically launched if all are met.

[0099] 1) Entering the range distance

[0100] When the distance L between the UAV and the target is less than or equal to 1.2 times the standard range L of the weapon s , that is, L ≤ 1.2L s , it is considered that the target enters the attack range, and attack tasks can be carried out within this distance.

[0101] 2) Azimuth locking

[0102] According to the distance L between the UAV and the target, the line-of-sight azimuth angle ψ G , the yaw angle ψ of the UAV, and the azimuth angle ψ of the weapon installation 0 , the control range of the UAV azimuth angle required to hit the target can be calculated. When the azimuth deviation angle ψ e between the UAV and the target meets certain conditions, it is determined that the azimuth locking is successful.

[0103] 3) Pitch locking

[0104] Similarly, according to the distance L between the UAV and the target, the line-of-sight elevation angle θ G , the pitch angle θ of the UAV, and the elevation angle θ of the weapon installation 0 , the control range of the UAV elevation angle required to hit the target can be calculated. When the pitch deviation angle θ e between the UAV and the target meets certain conditions, it is determined that the pitch locking is successful.

[0105] Specifically, the attack determination conditions are as follows:

[0106] (Ltan(θ e )) 2 +(Ltan(ψ e )) 2 ≤(R T +R B ) 2 (2)

[0107] Among them, the azimuth deviation angle ψ e, it can be calculated through the line-of-sight azimuth angle ψ G , the UAV yaw angle ψ, and the weapon installation azimuth angle ψ 0 as follows:

[0108] ψ e = ψ G - ψ - ψ 0 (3)

[0109] The pitch deviation angle θ e , it can be calculated through the line-of-sight elevation angle θ G , the UAV pitch angle θ, and the weapon installation elevation angle θ 0 as follows:

[0110] θ e = θ G - θ - θ 0 (4)

[0111] The ammunition dispersion radius R at the current aircraft-target distance B , it can be calculated through the ammunition dispersion radius R under the weapon standard range s , the weapon standard range L s and the aircraft-target distance L as follows:

[0112]

[0113] After it is monitored that the range, azimuth lock, and pitch lock are satisfied during the UAV pre-attack phase, ammunition is automatically launched to attack the target.

[0114] During this stage, the longitudinal control of the UAV is pitch tracking control, and the lateral and longitudinal control maintains azimuth tracking control to further accurately control the flight attitude of the UAV, so that the azimuth deviation angle ψ e and the pitch deviation angle θ e enter the range determined by the attack judgment conditions, and the engine maintains speed control.

[0115] In the embodiment: During the attitude adjustment stage, the UAV is guided to approach the target and rough alignment is completed. After the aircraft-target distance L enters the firing range of the gun, the attack process transfers to the pre-attack stage. This stage mainly adjusts the UAV attitude to achieve accurate azimuth lock and pitch lock. The lateral and longitudinal control maintains the azimuth tracking control strategy to further reduce the azimuth deviation angle ψ e , and longitudinally uses the pitch tracking control strategy to further reduce the pitch deviation angle θ e .

[0116] Based on the line-of-sight azimuth angle ψ G , the UAV yaw angle ψ, the weapon installation azimuth angle ψ 0 and formula (3), calculate the azimuth deviation angle ψ e ; based on the line-of-sight elevation angle θ G, the pitch angle θ of the UAV and the elevation angle θ of the weapon mounting 0 and calculate the pitch deviation angle θ using formula (4) e ; Based on the ammunition dispersion radius R under the standard range of the weapon s , the standard range L of the weapon s , the aircraft-target distance L and formula (5) to calculate the ammunition dispersion radius R at the current aircraft-target distance B .

[0117] Furthermore, use the left side of the inequality in formula (2) to calculate the alignable range of the current UAV attitude; Based on the ammunition dispersion radius R at the current aircraft-target distance B , the target radius R T and the right side of the inequality in formula (2) to calculate the required alignable range for attacking the target. When the alignable range is within the required alignable range, that is, formula (2) is judged to pass and the firing opportunity is reached, the UAV's on-board weapon automatically fires to carry out the attack; If the judgment condition cannot be passed due to other interferences such as the environment, the UAV judges whether it meets the evacuation condition of the minimum roll distance L min between the UAV and the target during the continuous alignment process. After meeting the evacuation condition, it still enters the evacuation stage.

[0118] c) Attack stage

[0119] After the precise alignment in the pre-attack stage, the UAV can carry out a firing strike. Taking the firing moment as the start of this stage, the attack time can be pre-loaded. The firing time is determined by the ammunition quantity of the mounted gun. After firing all the ammunition, it enters the evacuation stage, or when the aircraft-target distance L reaches the evacuation condition of the minimum roll distance L min , that is, L ≤ L min , stop the attack and enter the evacuation stage.

[0120] d) Evacuation stage

[0121] Taking into account the flight altitude, flight speed, maximum roll angle and minimum measurement distance of the seeker of the UAV, etc., the minimum roll distance L min is pre-set before the UAV takes off. When the UAV enters the evacuation stage, the UAV quickly turns to avoid the target area.

[0122] This stage uses the current altitude H of the UAV as the altitude command for altitude control and the maximum roll angle of the UAV as the command for roll control to complete the lateral and heading control. That is, longitudinally using the current altitude of the UAV as the altitude control command, laterally and heading using the maximum roll angle of the UAV as the roll angle command, and the engine maintaining speed control, so that the UAV yaws away from the target area to ensure the flight safety of the UAV and prepare for re-entering the attack process.

[0123] In this stage, the longitudinal control of the UAV is altitude control, and the lateral-directional control is roll control. That is, longitudinally, the current altitude of the UAV is used as the altitude control command, laterally, the maximum roll angle of the UAV is used as the roll angle command, and the engine maintains speed control to make the UAV yaw away from the target area to ensure the safety of the UAV.

[0124] To support the UAV control logic in each attack stage, an attitude control strategy is adaptively designed. The control surfaces selected for the fixed-wing UAV in this invention are the elevator and aileron. The longitudinal control channel mainly uses the elevator to control the pitch angle of the UAV to achieve altitude control and pitch tracking control. The lateral-directional control channel uses the aileron to control the azimuth angle of the UAV to achieve roll control and azimuth tracking control. The flight speed control mainly relies on the throttle to control the engine thrust to keep the UAV speed stable at the desired speed.

[0125] Specifically, the longitudinal control channel mainly has two control modes: altitude control and pitch tracking control.

[0126] The altitude control takes the target flight altitude H T as the given altitude H g for the UAV flight altitude. According to the current flight altitude H of the UAV and the given altitude H g for the flight altitude, the given pitch angle θ g of the UAV is calculated; the pitch tracking control is based on the pitch deviation angle θ e to calculate the given pitch angle θ g of the UAV. Further, based on the pitch angle θ, the given pitch angle θ g , the pitch angular velocity q of the UAV, and the roll angle of the UAV, the given elevator deflection δ e is calculated to make the UAV track this θ g .

[0127] The elevator control method is as follows:

[0128]

[0129] In the formula:

[0130] k θ 、k q 、k θi 、 are elevator control parameters, taking 1.0, 0.2, 0, 0.1 respectively;

[0131] k h 、k hi are given pitch angle control parameters, taking 1.0, 0.01 respectively;

[0132] k θ 、k θi 、k θdThe pitch tracking control parameters are taken as 2.0, 0.2, and 0.1 respectively.

[0133] Specifically, there are mainly two control modes in the lateral and longitudinal control channels: azimuth tracking control and roll control.

[0134] The azimuth tracking control is based on the azimuth deviation angle ψ e , and calculates the commanded roll angle of the UAV The roll control calculates the commanded roll angle of the UAV with the maximum roll angle of the UAV Further, with the roll angle of the UAV The commanded roll angle of the UAV The commanded roll angle of the UAV The commanded aileron deflection δ is calculated from the roll angle rate p of the UAV a , so that the UAV tracks this

[0135] The aileron control method is as follows:

[0136]

[0137] In the formula:

[0138] k p , are aileron control parameters, taken as 1, 0.5, and 0.5 respectively;

[0139] k ψ , k ψi , k ψd are commanded roll angle control parameters, taken as 1, 0.2, and 0 respectively.

[0140] Based on the above attack process, pre-attack method and control law design of the UAV in air combat, an attack method for a gun-carrying fixed-wing UAV is formed for low-speed or stationary targets in the air.

[0141] Finally, it is determined whether the UAV mission is completed. If the specified attack mission of the UAV is completed, the attack process ends. If the mission needs to be continued, go back to step 1 to rediscover the target and implement the attack.

[0142] First of all, starting from the discovery of the target by the UAV, the process of the UAV attacking an aerial target is generally described, mainly including the attitude adjustment stage, the pre-attack stage and the evacuation stage. Among them, the attitude adjustment stage mainly makes rough alignment preparations for the pre-attack stage; the pre-attack stage is the core of this attack method, realizing the automatic alignment and attack of the UAV; the evacuation stage ensures the flight safety of the UAV. Secondly, the attack determination conditions adopted in the pre-attack stage are described in detail, mainly including the azimuth locking method in the lateral and longitudinal directions and the pitch locking method in the longitudinal direction, and automatically firing at the target after the locking is completed. Finally, the control strategy involved in the entire attack process of the present invention is described to realize the closed-loop of the full-process attack method.

[0143] As can be seen from the above, an attack method for an aerial target by a gun-carrying fixed-wing UAV proposed by the present invention refines the attack process, clarifies the precise alignment method for pre-attack, designs the UAV attitude control law, can quickly maneuver after the seeker discovers the target and guide the UAV to approach the target, complete further precise alignment based on the UAV attitude control, improve the automatic attack trigger conditions, ensure the timeliness of the attack, effectively attack low-speed aerial targets, and improve the attack accuracy of the UAV.

Claims

1. A method for attacking a low-speed target in the air by a fixed-wing UAV, characterized in that: Starting from the drone discovering the target, the attack process includes: posture adjustment phase, pre-attack phase, attack phase, and evacuation phase; the process steps are as follows: Attitude adjustment phase: After the drone locks on the target, it moves at the target height H T Adjust your own flight altitude H to be equal to the target altitude H T , so that the UAV and the target are at the same level; At the same time, adjust the direction of the drone's nose to point to the target, so that the drone and the target form a tail-chasing or head-on relationship to complete the rough alignment; Pre-attack stage: The UAV approaches the target by tail pursuit or head-on approach. After entering the range, the UAV pitch angle θ and yaw angle ψ are quickly adjusted to accurately aim the installed weapons at the target, and the UAV automatically fires when the attack conditions are met; In the tracking control of the UAV flight attitude in the pre-attack stage, the UAV longitudinal control is pitch tracking control, so that the azimuth deviation angle ψ e and the pitch deviation angle θ e Entering the range determined by the attack determination conditions, the engine maintains speed control; The attack condition is: (Ltan(θ e )) 2 +(Ltan(ψ e )) 2 ≤(R T +R B ) 2 , L is the distance between the aircraft and the target, θ e is the pitch deviation angle between the UAV and the target, ψ e is the azimuth deviation angle between the UAV and the target, R T The radius of the projected circle on the side of the target that receives the attack, R B The ammunition diffusion radius at the current target distance; Attack phase: The beginning of this phase is when the firing begins, and the end of this phase is when the ammunition is used up and the phase begins with the withdrawal phase; Evacuation phase: After the attack is completed, the drone quickly turns to avoid the target area; During the rapid turning maneuver, the UAV implements longitudinal control and lateral heading control; The longitudinal control includes altitude control and pitch tracking control; The lateral heading control includes azimuth tracking control and rolling control; The altitude control is based on the target flight altitude H T H is the given value of the UAV flight altitude g , according to the current flight altitude H of the UAV and the given flight altitude H g Calculate the given pitch angle θ of the drone g ; The pitch tracking control is based on the pitch deviation angle θ e , calculate the given pitch angle θ of the drone g ; Then use the pitch angle θ of the drone and the given pitch angle θ g , the pitch angular velocity q of the UAV and the roll angle of the UAV Calculate the given elevator deflection δ e , so that the drone can track the θ g ; The azimuth tracking control is based on the azimuth deviation angle ψ e , calculate the given amount of the drone's roll angle The rolling control is based on the maximum rolling angle of the UAV Calculate the given amount of the drone's roll angle Then the drone roll angle UAV roll angle given value The UAV roll angular velocity p is used to calculate the UAV aileron given rudder deflection δ a , so that the drone can track the 2. The method for attacking a low-speed target in the air by a fixed-wing unmanned aerial vehicle according to claim 1, characterized in that: The target height H T When adjusting its own flight altitude H, the longitudinal control of the UAV is altitude control, and the lateral heading control is azimuth tracking control. By adjusting the flight altitude H and yaw angle ψ of the UAV, the altitude deviation ΔH and azimuth deviation angle ψ are adjusted. e The target height H is controlled to 0, and the engine maintains speed control; T The relationship between the flight altitude H and the flight height is: T =H+Lsin(θ G ), where: L is the distance between the aircraft and the target, θ G is the sight height angle θ G .

3. The method for attacking a low-speed target in the air by a fixed-wing unmanned aerial vehicle according to claim 1, characterized in that: The attack conditions meet three items:

1. Entering the range: When the target distance L is less than or equal to 1.2 times the standard range of the weapon L s , i.e. L≤1.2L s When the target enters the attack range, the attack mission is carried out within this distance; 2. Azimuth lock: according to the aircraft-to-eye distance L, the line of sight azimuth angle ψ G , the UAV yaw angle ψ and the weapon installation azimuth angle ψ0, calculate the UAV azimuth control range required to hit the target, when the azimuth deviation angle ψ between the UAV and the target e If certain conditions are met, the azimuth lock is determined to be successful; 3. Pitch lock: based on the aircraft-to-eye distance L and the line-of-sight height angle θ G , the pitch angle of the drone θ, the height angle of the weapon installation θ0, calculate the drone height angle control range required to hit the target, when the pitch deviation angle between the drone and the target meets the condition θ e , it is determined that the pitch lock is successful.

4. The method for attacking a low-speed target in the air by a fixed-wing unmanned aerial vehicle according to claim 1, characterized in that: The azimuth deviation angle ψ e Satisfy certain conditions: e =ψ G -ψ-ψ0, where: ψ G is the line of sight azimuth, ψ is the yaw angle of the UAV, and ψ0 is the weapon installation azimuth.

5. The method for attacking a low-speed target in the air by a fixed-wing UAV according to claim 1, characterized in that: The pitch deviation angle satisfies the condition θ e :θ e =θ G -θ-θ0, where: θ G is the sight angle, θ is the pitch angle of the drone, and θ0 is the weapon installation angle.

6. The method for attacking a low-speed target in the air by a fixed-wing UAV according to claim 1, characterized in that: The ammunition dispersion radius at the current target distance Where: R s is the ammunition diffusion radius at the standard range of the weapon, L s is the standard range of the weapon and L is the distance between the aircraft and the target.

7. The method for attacking a low-speed target in the air by a fixed-wing UAV according to claim 1, characterized in that: The evacuation condition for entering the evacuation phase is that the aircraft-to-target distance L reaches the minimum rolling distance L. min When the evacuation condition is met, that is, L≤L min , stop the attack and enter the evacuation phase.

8. The method for attacking a low-speed target in the air by a fixed-wing UAV according to claim 1, characterized in that: The elevator given rudder deflection δ e , so that the drone can track the θ g The calculation is: Where: k θ , k q , k θi , is the elevator control parameter; k h , k hi is the pitch angle given value control parameter; k θ , k θi , k θd Pitch tracking control parameter.

9. The method for attacking a low-speed target in the air by a fixed-wing UAV according to claim 1, characterized in that: The UAV aileron given rudder deflection δ a , so that the drone can track the The calculation is: in: k p , is the aileron control parameter; k ψ , k ψi , k ψd It is the control parameter of the roll angle given amount.

10. A computer program product, characterized in that It includes computer executable instructions, which are used to implement the fixed-wing unmanned aerial vehicle low-speed target attack method as described in claims 1 to 9 when executed.

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