A segmented guidance method suitable for coordinated strike of multiple UAVs

Abstract

The present invention discloses a segmented guidance method suitable for coordinated strikes of multiple UAVs, including: dividing the strike process of the UAV cluster into an outer-circle coordinated approach segment, a circumferential coordinated reconnaissance segment, and an inner-circle coordinated strike terminal guidance segment; performing coordinated approach track planning in the outer-circle coordinated approach segment; adopting multi-UAV circular formation guidance in the circumferential coordinated reconnaissance segment, by tracking guidance points evenly distributed on the threat circle and adjusting the flight speed in real time; and adopting a time coordinated guidance method based on speed regulation in the inner-circle coordinated strike terminal guidance segment. The present invention is applied to the field of UAV track planning, and designs a coordinated guidance law for attack angles of multiple UAVs and a coordinated speed adjustment strategy under the framework of consistency theory, effectively utilizing the adjustable characteristics of the speed size / direction of the UAV, improving the dynamic coordinated adjustment range, anti-interference capability, and control accuracy of the attack time / angle, and realizing the coordinated strike of multiple UAVs on targets under the premise of meeting the strike time / space constraints.

Description

Technical Field

[0001] The invention relates to the technical field of unmanned aerial vehicle track planning, and in particular to a segmented guidance method suitable for coordinated attack of multiple unmanned aerial vehicles. Background Art

[0002] As a new force that has emerged suddenly, drones have gradually evolved from reconnaissance and support to the main role of attack. Suicide drones have the advantages of long-term cruising and high-speed penetration. Compared with conventional missiles, they have strong continuous reconnaissance and surveillance capabilities, no need to preset the target position, and have stronger real-time strike capabilities against time-sensitive targets; compared with conventional drones, they have compact structure, concealment and strong penetration capabilities; in addition, the suicide feature also allows them to avoid the passive situation of being captured by the enemy, so that they can boldly move forward to deep areas to perform high-risk tasks.

[0003] When multiple drones coordinate to carry out suicide attacks on a target, the target's air defense system's firepower channel can be instantly saturated, greatly increasing the probability of penetration. In recent years, there have been many successful cases of using densely packed suicide drone groups to carry out salvo attacks in local conflicts, indicating that this combat method can effectively improve combat effectiveness. Drone swarm tactics can transform quantitative advantages into qualitative advantages. The overall function far exceeds the superposition of individual drones, and partial losses will not have a destructive impact on the overall operation. The system's survivability is greatly improved, and the damage effect on high-value enemy targets is significantly enhanced.

[0004] At present, the guidance methods in the process of coordinated strikes by multiple UAVs mostly draw on the idea of ​​coordinated guidance and control of missile groups. They fail to give full play to the advantages of the UAV's dynamic characteristics, and fail to effectively utilize the characteristics of UAVs such as long-term hovering, online trajectory planning, and adjustable speed. Therefore, the combat effectiveness of coordinated strikes by multiple UAVs is greatly limited. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the present invention provides a segmented guidance method suitable for coordinated strikes by multiple UAVs, which can achieve coordinated strikes by multiple UAVs on targets under the premise of satisfying the strike time / space constraints.

[0006] To achieve the above object, the present invention provides a segmented guidance method suitable for coordinated strike of multiple UAVs, comprising the following steps:

[0007] Model the circular area around the target as the threat circle;

[0008] Based on the threat circle, the strike process of the drone swarm is divided into the outer circle coordinated approach phase, the circumference coordinated reconnaissance phase and the inner circle coordinated strike terminal guidance phase.

[0009] in:

[0010] In the coordinated approach section outside the circle, the coordinated approach trajectory planning is performed with the constraints that the UAVs are evenly distributed on the circumference of the threat circle in space and all the UAVs arrive at the circumference of the threat circle at the same time in time;

[0011] In the circular cooperative reconnaissance phase, a multi-UAV circular formation guidance method is adopted, and each UAV realizes circular formation flight by tracking guidance points evenly distributed on the circumference of the threat circle and adjusting the flight speed in real time;

[0012] In the terminal guidance stage of coordinated strike within the circle, a time coordinated guidance method based on speed regulation is adopted to eliminate the time accumulation deviation and realize the coordinated attack task under time and space constraints.

[0013] In one embodiment, the track planning for the coordinated approach in the outer-circle coordinated approach section is specifically as follows:

[0014] Establish a two-dimensional horizontal flight plane coordinate system, project the current position information of the drone cluster and the position information of the target into the flight plane coordinate system, and determine the threat circle in the flight plane coordinate system;

[0015] Based on the initial state of each drone at time t0 and the f The required state at the moment, the Dobbins path is used for trajectory planning, and the optimization objective function J is established as:

[0016]

[0017] In the formula, i=1,2,···,n represents the number of drones, and n is the number of drones in the drone cluster; represents the i-th phase difference, where the phase difference refers to the corresponding central angle between two adjacent drones on the circumference of the threat circle; t fi represents the time when the i-th UAV arrives on the circumference of the threat circle; k1 is the spatial coordination weight, k2 is the time coordination weight, k3 is the time minimization weight, and D(·) represents the variance calculation;

[0018] By solving the above optimization objective function based on the optimization algorithm, the trajectory planning of the drone cluster approaching the threat circle in a coordinated manner can be realized.

[0019] In one embodiment, a leader-wingman architecture is adopted in the process of adopting multi-UAV circular formation guidance in the circular cooperative reconnaissance phase, wherein:

[0020] The guidance strategy of the lead aircraft is:

[0021]

[0022] In the formula, a ⊥,.0 is the normal acceleration control command of the lead machine, V0 is the speed of the lead machine, ηi is the angle between the lead aircraft’s guidance line and the velocity vector, L0 is the length of the lead aircraft’s guidance line;

[0023] The guidance strategy of the wingman is:

[0024]

[0025] Where j=1, 2, ···, n-1 represents the number of the wingman, ΔV c,j is the speed adjustment of the jth wingman, k V is the gain, d j is the length of the guidance line of the jth wingman, a ⊥,j is the normal acceleration control instruction of the jth wingman, V j is the speed of the jth wingman, η j is the angle between the guidance line and the velocity vector of the jth wingman.

[0026] In one embodiment, the length of the wingman's guide wire is:

[0027]

[0028] Where p0 is the leading point of the lead aircraft on the circumference of the threat circle, and f1(·) represents the calculation of the intersection point of the two circles, that is, p 长机 The intersection of a circle with a center and a radius of L0 and the circumference of the threat circle. ,p 长机 is the current position of the lead aircraft, p T is the position of the target, r is the radius of the threat circle; p j is the guidance point of the jth wingman on the circumference of the threat circle, f2(·) represents the coordinates of a point on the circumference in polar coordinate form, is the phase difference between the jth wingman and the lead aircraft, f3(·) represents the distance calculation between two points in space, p 僚机，j is the current position of the jth wingman.

[0029] In one embodiment, the process of using time coordinated guidance based on speed regulation in the coordinated strike terminal guidance stage within the circle is specifically as follows:

[0030] The flight time estimate of each UAV is obtained based on the proportional guidance law;

[0031] Based on the proportional guidance law and the flight time estimation of each UAV, the terminal guidance control strategy in the two-dimensional plane is obtained;

[0032] Based on the terminal guidance control strategy in the two-dimensional plane, the time-coordinated terminal guidance control strategy of the UAV cluster in the three-dimensional space is obtained.

[0033] In one embodiment, the flight time estimation of each UAV is obtained based on the proportional guidance law, specifically:

[0034] The proportional guidance law is selected as the basic framework for the terminal guidance of the UAV cluster. The proportional guidance law is:

[0035]

[0036] In the formula, i=1,2,···,n represents the number of drones, n is the number of drones in the drone cluster; N is the proportional coefficient, ψ i is the heading angle of the i-th UAV, t represents the current moment, and λ i (t) The angular velocity of the i-th UAV at the current moment, a ⊥,i The normal acceleration control command of the i-th UAV, V i (t) is the speed of the i-th UAV at the current moment;

[0037] The estimated flight time of each UAV is obtained based on the proportional guidance law:

[0038]

[0039] In the formula, is the estimated flight time of the i-th UAV at the current moment, R i (t) is the distance between the position of the i-th UAV at the current moment and the target, σ i (t) is the velocity lead angle of the i-th UAV at the current moment.

[0040] In one embodiment, the terminal guidance control strategy in the two-dimensional plane is specifically:

[0041]

[0042] Where ΔV c,i (t) is the speed adjustment of the i-th UAV at the current moment, T go,i is the expected arrival time of the i-th UAV, V min is the minimum flight speed of the drone, V max is the maximum flight speed of the drone, a max is the maximum normal acceleration of the UAV, a ⊥,i (t) is the normal acceleration control instruction of the i-th UAV at the current moment; a b,i is the additional component of the normal acceleration control command of the i-th UAV, which is:

[0043]

[0044] In the formula, k bIndicates the influence of time constraints, R i (0) is the distance of the i-th UAV relative to the target to be attacked at the moment of switching to the final guidance, is the estimated remaining flight time of the i-th UAV at the moment of switching to the final guidance.

[0045] In one embodiment, the terminal guidance control strategy based on the two-dimensional plane is used to obtain the time-coordinated terminal guidance control strategy of the UAV cluster in three-dimensional space, which is specifically:

[0046] Convert the angular velocity of the drone's line of sight in three-dimensional space to the drone's body coordinate system:

[0047]

[0048]

[0049] In the formula, represents the longitudinal and lateral components of the current line of sight angular velocity of the i-th UAV in the UAV body coordinate system, γ i is the pitch angle of the i-th UAV, is the three-axis component of the line of sight angular velocity of the i-th UAV in three-dimensional space at the current moment;

[0050] In order to achieve the time coordination of the terminal guidance process in three-dimensional space, the terminal guidance control strategy in the two-dimensional plane is used to adjust the UAV in the horizontal direction, and the proportional guidance law is used to adjust the UAV in the vertical direction. Therefore, the time coordinated terminal guidance control strategy of the UAV cluster in three-dimensional space is obtained as follows:

[0051]

[0052] In the formula, a lat,i (t) is the lateral acceleration control instruction of the i-th UAV at the current moment, is the maximum lateral acceleration of the UAV, a lon,i (t) is the longitudinal acceleration control instruction of the i-th UAV at the current moment, is the maximum longitudinal acceleration of the UAV.

[0053] In one embodiment, T is coordinated in real time during terminal guidance. go,i ;or

[0054] T go,i is a constant value that satisfies the constraints.

[0055] The present invention provides a segmented guidance method suitable for coordinated strikes by multiple UAVs, which divides the strike process of a cluster of UAVs into an outer-circle coordinated approach segment, a circumferential coordinated reconnaissance segment and an inner-circle coordinated strike terminal guidance segment. A coordinated guidance law for attack angles of multiple UAVs and a coordinated speed adjustment strategy under the framework of consistency theory are designed, and the adjustable characteristics of the speed size / direction of the UAVs are effectively utilized to effectively improve the dynamic coordinated adjustment range of the attack time / angle, the anti-interference capability and the control accuracy, so as to realize the coordinated strike of multiple UAVs on targets under the premise of meeting the strike time / space constraints. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0057] Figure 1 This is a schematic diagram of segmented guidance of multiple UAVs in an embodiment of the present invention;

[0058] Figure 2 It is a schematic diagram of the path planning principle based on the Dubins curve for the outer circle collaborative approach segment in an embodiment of the present invention;

[0059] Figure 3 It is a schematic diagram of the nonlinear guidance of the circumferential cooperative reconnaissance segment in an embodiment of the present invention;

[0060] Figure 4 Schematic diagram of the guidance strategy for circular formation flight of three UAVs in the circular cooperative reconnaissance phase in an embodiment of the present invention;

[0061] Figure 5 It is a guidance geometry diagram in a two-dimensional plane of the terminal guidance section of the coordinated strike within a circle in an embodiment of the present invention;

[0062] Figure 6 It is a guidance principle diagram in three-dimensional space of the terminal guidance section of the coordinated strike within a circle in an embodiment of the present invention.

[0063] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0064] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0065] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0066] In the description of the present invention, "multiple" means at least two, such as two, three, etc., unless otherwise clearly and specifically limited. In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the ability of ordinary technicians in the field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the protection scope required by the present invention.

[0067] like Figure 1 The present embodiment discloses a segmented guidance method suitable for coordinated strike of multiple UAVs, comprising the following steps:

[0068] First, the circular area around the target is modeled as a threat circle, and the influence or interference of the enemy defense system within the circle cannot be ignored;

[0069] The attack process of the suicide drone swarm is divided into the outer circle coordinated approach phase, the circumference coordinated reconnaissance phase and the inner circle coordinated attack terminal guidance phase based on the circumference of the threat circle. Before the attack, the drone will not enter the circumference of the threat circle, so the reconnaissance mission against the target also needs to be carried out on the circle. Among them:

[0070] In the outer circle collaborative approach section, the coordinated approach trajectory planning is performed with the constraints that the drones are evenly distributed on the circumference of the threat circle in space and all drones arrive at the circumference of the threat circle at the same time. Among them, the uniform distribution of drones on the circumference of the threat circle can achieve collaborative observation or all-round saturation attack on the target, and the simultaneous arrival of all drones at the circumference of the threat circle can be achieved through the coordinated adjustment of the trajectory of the outer circle collaborative approach section;

[0071] In the circular cooperative reconnaissance phase, a multi-UAV circular formation guidance method is adopted, and each UAV realizes circular formation flight by tracking guidance points evenly distributed on the circumference of the threat circle and adjusting the flight speed in real time;

[0072] In the terminal guidance stage of coordinated strike within the circle, a time coordinated guidance method based on speed regulation is adopted to eliminate the time accumulation deviation and realize the coordinated attack task under time and space constraints.

[0073] In this embodiment, the specific implementation method of the track planning for the coordinated approach in the outer circle coordinated approach section is as follows:

[0074] To simplify the problem, the path planning of the outer circle collaborative approach segment only considers the two-dimensional horizontal plane, so a two-dimensional horizontal flight plane coordinate system is established, and the current position information of the drone cluster and the position information of the target are projected into the flight plane coordinate system, and the threat circle is determined in the flight plane coordinate system, where "current" refers to the initial moment (t0). Figure 2 , the initial state of the drone at time t0 is represented by position P0, ground speed V0, and heading angle ψ0, as Figure 2 As shown in Case 1. At t f At time (i.e. the time when the UAV reaches the circumference of the threat circle), the state of the UAV is determined by the position of the target P T , the distance r (threat circle radius) and azimuth (the opposite direction of line of sight (LOS)) of the drone relative to the target, and the ground speed V f These variables are selected to facilitate the modeling and optimization of multi-UAV coordinated control.

[0075] According to the state at time t0 and t f The required state at the moment, the Dobins path is used for trajectory planning. The minimum turning radius is limited by the UAV dynamics r0 ≥ r min And r f ≥r min , where r0 is the turning radius of the first arc in the Dubins path, r f is the turning radius of the second arc in the Dobbins path, r min is the minimum turning radius of the drone. When planning the guidance trajectory, it is assumed that the speed of the drone is constant, and the turning radius can be set to be greater than r min Any value of can be adjusted as needed to achieve coordinated arrival with spatiotemporal constraints.

[0076] Different mission types have different requirements for the speed direction when reaching the threat circle. For example, if the subsequent collaborative reconnaissance mission of the circular collaborative reconnaissance segment is required, the speed lead angle is 90°. Figure 2 As shown in Case 1 in ; when a direct strike is required, the velocity lead angle σ is preferably 0°, such as Figure 2 As shown in Case 2 in the figure; for general cases, other angles can also be coordinated, such as Figure 2In case 3 in , the speed lead angle is set to -30°. In this embodiment, since there is a collaborative reconnaissance task in the circular collaborative reconnaissance segment, the speed lead angle of each drone in the drone cluster is set to 90° during the collaborative approach trajectory planning process. Of course, for other specific tasks, the required speed lead angle can also be given.

[0077] In this embodiment, based on the initial state of each drone at time t0 and the initial state of each drone at time t f The required state at the moment, the Dobbins path is used for trajectory planning, and the optimization objective function J is established as:

[0078]

[0079] In the formula, i=1,2,···,n represents the number of drones, and n is the number of drones in the drone cluster; represents the i-th phase difference, where the phase difference refers to the corresponding central angle between two adjacent drones on the circumference of the threat circle; t fi represents the time when the i-th UAV arrives on the circumference of the threat circle; k1 is the spatial coordination weight, k2 is the time coordination weight, k3 is the time minimization weight, and D(·) represents the variance calculation. It should be noted that parameters such as UAV speed and speed lead angle can also be added to the objective function in a similar form to achieve specific collaboration goals.

[0080] For the above optimization objective function, the Particle Swarm Optimization (PSO) algorithm can be used to find feasible results for the path planning problem, that is, to achieve the trajectory planning of the UAV cluster approaching the threat circle in a coordinated manner. In the specific implementation process, other optimization solutions can also be selected to replace the PSO algorithm, such as the ant colony algorithm, simulated annealing algorithm, etc.

[0081] In this embodiment, the specific implementation method of performing multi-UAV circular formation guidance in the circular cooperative reconnaissance phase is as follows:

[0082] The trajectory tracking of the UAV is realized by using nonlinear guidance, and the lateral acceleration command is generated by using the guidance point, such as Figure 3 As shown, the lateral acceleration command is determined by the following formula (2):

[0083]

[0084] In the formula, a ⊥ is the normal acceleration control command of the UAV, V is the velocity of the UAV, η is the angle between the UAV's guide line and the velocity vector, and L is the length of the UAV's guide line. This method can also track straight and curved trajectories well in windy conditions.

[0085] In the process of circular formation guidance of multiple UAVs in the circular cooperative reconnaissance phase, the leader-wingman architecture is adopted. In order to keep multiple UAVs in circular formation and perform cooperative reconnaissance missions, it is necessary to ensure that the guidance points are evenly distributed on the circle. For this specific case of three UAVs cooperating, the phase difference between the leader and the wingman is set to like Figure 4 As shown. Figure 3 The guidance of a single UAV in the formation, the length of the guidance line is fixed to L0. The guidance point is located on the path to be tracked, which is determined by the position of the UAV and the length of the guidance line. When flying in a circular formation, the leader uses the guidance strategy in formula (2), that is, the guidance strategy of the leader is:

[0086]

[0087] In the formula, a ⊥,.0 is the normal acceleration control command of the lead machine, V0 is the speed of the lead machine, η i is the angle between the guide line and the velocity vector of the lead aircraft, and L0 is the length of the guide line of the lead aircraft. The velocity V0 of the lead aircraft can be adjusted in real time according to the mission requirements or directly set to a constant value.

[0088] During formation control, the actual distance d between the wingman and the coordination guidance point j will change to:

[0089]

[0090] Where p0 is the leading point of the lead aircraft on the circumference of the threat circle, and f1(·) represents the calculation of the intersection point of the two circles, that is, p 长机 The intersection of a circle with a center and a radius of L0 and the circumference of the threat circle. ,p 长机 is the current position of the lead aircraft, p T is the position of the target, r is the radius of the threat circle; p j is the guidance point of the jth wingman on the circumference of the threat circle, f2(·) represents the coordinates of a point on the circumference in polar coordinate form, is the phase difference between the jth wingman and the lead aircraft, d j is the length of the guidance line of the jth wingman, f3(·) represents the distance calculation between two points in space, and p 僚机，j is the current position of the jth wingman.

[0091] The wingman guidance strategy for circular formation flying is obtained as follows:

[0092]

[0093] Where j=1, 2, ···, n-1 represents the number of the wingman, ΔVc,j is the speed adjustment of the jth wingman, k V is the gain, a ⊥,j is the normal acceleration control instruction of the jth wingman, V j is the speed of the jth wingman, η j is the angle between the guidance line and the velocity vector of the jth wingman. j According to the current guide line length d j (t) and the length of the long aircraft guidance line L0 are adjusted. This guidance strategy enables the UAVs to accurately track the guidance points, which are evenly distributed on the circumference, thereby realizing a circular flight formation and collaboratively performing reconnaissance missions.

[0094] In this embodiment, the specific implementation method of using time coordinated guidance based on speed regulation in the terminal guidance stage of coordinated strike within the circle is:

[0095] The flight time estimate of each UAV is obtained based on the proportional guidance law;

[0096] Based on the proportional guidance law and the flight time estimation of each UAV, the terminal guidance control strategy in the two-dimensional plane is obtained;

[0097] Based on the terminal guidance control strategy in the two-dimensional plane, the time-coordinated terminal guidance control strategy of the UAV cluster in the three-dimensional space is obtained.

[0098] Specifically:

[0099] The dynamics of the UAV in three-dimensional space can be decoupled into the motion of two orthogonal planes. First, the problem of coordinated terminal guidance in two-dimensional plane is studied, such as Figure 5 As shown. For a stationary target, the relative motion equation between the UAV and the target can be expressed as:

[0100]

[0101] In the formula, R is the relative distance and V is the flight speed of the drone. ⊥ is the normal acceleration control command, and the normal acceleration is perpendicular to the velocity direction; λ is the line of sight angle, ψ is the heading angle of the UAV. σ is the velocity lead angle. It should be noted that the guidance process for a moving target can be described by modifying equation (6).

[0102] The proportional guidance law is selected as the basic framework for the terminal guidance of the UAV cluster. The proportional guidance law is:

[0103]

[0104] In the formula, i=1,2,···,n represents the number of drones, n is the number of drones in the drone cluster; N is the proportional coefficient, ψi is the heading angle of the i-th UAV, t represents the current moment, and λ i (t) The angular velocity of the i-th UAV at the current moment, a ⊥,i The normal acceleration control command of the i-th UAV, V i (t) is the speed of the i-th UAV at the current moment;

[0105] The estimated flight time of each UAV is obtained based on the proportional guidance law:

[0106]

[0107] In the formula, is the estimated flight time of the i-th UAV at the current moment, R i (t) is the distance between the position of the i-th UAV at the current moment and the target, σ i (t) is the velocity lead angle of the i-th UAV at the current moment.

[0108] The time coordination type of the terminal guidance phase can be a salvo attack, that is, T go,i =T c ,i∈[1,n], or the strike time of each aircraft can be set with a corresponding delay, that is, T go,i =T c +ΔT i , where T go,i is the expected arrival time of the i-th UAV, T c is the time of simultaneous attack, ΔT i is the delay of the i-th drone when attacking according to a specific time sequence. In formula (8) The estimated value of is used as feedback to achieve cluster time coordination. Considering the adjustable speed of the UAV, time coordination is achieved by prioritizing speed regulation. However, the speed range is affected by conditions such as stall, aerodynamic drag, thrust, and regulation response lag. When the speed is close to the limit and still cannot meet the demand, the lateral overload command will be adjusted and the offset proportional guidance method will be adopted. Therefore, the terminal guidance control strategy in the two-dimensional plane is as follows:

[0109]

[0110] Where ΔV c,i (t) is the speed adjustment of the i-th UAV at the current moment, which is used to make Close(T go,i -t); V min is the minimum flight speed of the drone, V max is the maximum flight speed of the drone, a max is the maximum normal acceleration of the UAV, a ⊥,i(t) is the normal acceleration control instruction of the i-th UAV at the current moment; a b,i is the additional component of the normal acceleration control command of the i-th UAV, which is:

[0111]

[0112] In the formula, k b Indicates the influence of time constraints, R i (0) is the distance of the i-th UAV relative to the target to be attacked at the moment of switching to the final guidance, is the estimated remaining flight time of the i-th UAV at the moment of switching to the final guidance.

[0113] In practical applications, drones fly in three-dimensional space, such as Figure 6 The improved proportional guidance law is applied to the longitudinal channel and the lateral channel respectively, and the line of sight angular velocity of the UAV in three-dimensional space is converted to the UAV body coordinate system, which is:

[0114]

[0115] In the formula, represents the longitudinal and lateral components of the current line of sight angular velocity of the i-th UAV in the UAV body coordinate system, γ i is the pitch angle of the i-th UAV, is the three-axis component of the line of sight angular velocity of the i-th UAV in three-dimensional space at the current moment;

[0116] Because the time adjustment capability based on longitudinal maneuvers is usually very limited, in order to achieve the time coordination of the terminal guidance process in three-dimensional space, the terminal guidance control strategy in the two-dimensional plane is used to adjust the UAV in the lateral direction, and the proportional guidance law is used to adjust the UAV in the longitudinal direction. Therefore, the time coordinated terminal guidance control strategy of the UAV cluster in three-dimensional space is obtained as follows:

[0117]

[0118] In the formula, a lat,i (t) is the lateral acceleration control instruction of the i-th UAV at the current moment, is the maximum lateral acceleration of the UAV, a lon,i (t) is the longitudinal acceleration control instruction of the i-th UAV at the current moment, is the maximum longitudinal acceleration of the UAV. go,i It can be coordinated in real time during the terminal guidance process, or it can be taken as an appropriate constant that meets the constraints based on historical data.

[0119] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A segmented guidance method suitable for coordinated strike of multiple UAVs, characterized in that: The steps include: Model the circular area around the target as the threat circle; Based on the threat circle, the strike process of the drone swarm is divided into the outer circle coordinated approach phase, the circumference coordinated reconnaissance phase and the inner circle coordinated strike terminal guidance phase. in: In the coordinated approach section outside the circle, the coordinated approach trajectory planning is performed with the constraints that the UAVs are evenly distributed on the circumference of the threat circle in space and all the UAVs arrive at the circumference of the threat circle at the same time in time; In the circular cooperative reconnaissance phase, a multi-UAV circular formation guidance method is adopted, and each UAV realizes circular formation flight by tracking guidance points evenly distributed on the circumference of the threat circle and adjusting the flight speed in real time; In the terminal guidance stage of coordinated attack within the circle, a time coordinated guidance method based on speed regulation is adopted to eliminate time accumulation deviation and realize the coordinated attack task under time and space constraints; The specific track planning for the coordinated approach in the coordinated approach section outside the circle is: Establish a two-dimensional horizontal flight plane coordinate system, project the current position information of the drone cluster and the position information of the target into the flight plane coordinate system, and determine the threat circle in the flight plane coordinate system; Based on the drones t The initial state at time 0 and the state of each drone t f The desired state at the moment, using the Dubins path for trajectory planning, and establishing the optimization objective function J for: In the formula, i =1,2,···, n Indicates the number of the drone. n is the number of drones in the drone swarm; Indicates i Phase difference, where the phase difference refers to the central angle between two adjacent drones on the circumference of the threat circle; t fi Indicates i The time when the drone reaches the circumference of the threat circle; k 1 is the spatial coordination weight, k 2 is the time coordination weight, k 3 is the time minimization weight, D (·) represents variance calculation; By solving the above optimization objective function based on the optimization algorithm, the trajectory planning of the UAV cluster approaching the threat circle can be realized; In the process of adopting multi-UAV circular formation guidance in the circular cooperative reconnaissance phase, a leader-wingman architecture is adopted, wherein: The guidance strategy of the lead aircraft is: In the formula, a ⊥,0 is the normal acceleration control command of the lead aircraft, V 0 is the speed of the long machine, η i is the angle between the leader's guidance line and the velocity vector, L 0 is the guide line length of the long machine; The guidance strategy of the wingman is: In the formula, j =1,2,···, n -1 indicates the number of the wingman, Δ V c, j For the j The speed adjustment of the wingman, k V For gain, d j For the j The length of the wingman's guide line, a ⊥, j For the j The normal acceleration control command of the wingman, V j For the j The speed of the wingman, η j For the j The angle between the wingman's guidance line and velocity vector; The process of using time coordinated guidance based on speed regulation in the terminal guidance stage of coordinated strike within the circle is specifically as follows: The flight time estimate of each UAV is obtained based on the proportional guidance law; Based on the proportional guidance law and the flight time estimation of each UAV, the terminal guidance control strategy in the two-dimensional plane is obtained; Based on the terminal guidance control strategy in the two-dimensional plane, the time-coordinated terminal guidance control strategy of the UAV cluster in the three-dimensional space is obtained.

2. The segmented guidance method suitable for coordinated strike of multiple UAVs according to claim 1 is characterized in that: Length of the wingman's guide line d j The calculation method is: In the formula, p 0 is the leading point of the lead aircraft on the circumference of the threat circle. f 1(·) represents the calculation of the intersection point of two circles, that is, p 长机 As the center of the circle, L The intersection of the circle with a radius of 0 and the circumference of the threat circle, p 长机 is the current position of the lead aircraft, p T is the target location, r is the radius of the threat circle; p j For the j The wingman's guidance point on the circumference of the threat circle, f 2(·) represents the coordinates of a point on the circumference in polar coordinate form, For the j The phase difference between the wingman and the lead aircraft, =(360° / n ) j ; f 3(·) represents the distance calculation between two points in space, For the j The current position of the wingman.

3. The segmented guidance method suitable for coordinated strike of multiple UAVs according to claim 1 or 2, characterized in that: The flight time estimation of each UAV is obtained based on the proportional guidance law, specifically: The proportional guidance law is selected as the basic framework for the terminal guidance of the UAV cluster. The proportional guidance law is: In the formula, i =1,2,···, n Indicates the number of the drone. n is the number of drones in the drone swarm; N is the proportionality coefficient, For the i The heading angle of the drone, t Indicates the current moment, No. i The angular velocity of the UAV’s line of sight at the current moment, No. i The normal acceleration control command of the UAV, For the i The speed of the drone at the current moment; The estimated flight time of each UAV is obtained based on the proportional guidance law: In the formula, For the i The estimated flight time of the drone at the current moment, For the i The distance between the current position of the drone and the target, For the i The velocity lead angle of the UAV at the current moment.

4. The segmented guidance method suitable for coordinated strike of multiple UAVs according to claim 3 is characterized in that: The terminal guidance control strategy in the two-dimensional plane is specifically: In the formula, For the i The speed adjustment of the drone at the current moment, For the i The expected arrival time of the drone, is the minimum flight speed of the drone, is the maximum flight speed of the drone, is the maximum normal acceleration of the drone, For the i Normal acceleration control instructions of the UAV at the current moment; For the i The additional component of the normal acceleration control command of the UAV is: In the formula, k b Indicates the influence of time constraints, For the i The distance of the UAV relative to the target to be attacked at the moment of switching to terminal guidance, For the i Estimation of the remaining flight time of a UAV at the moment of switching to terminal guidance.

5. The segmented guidance method suitable for coordinated strike of multiple UAVs according to claim 4 is characterized in that: Based on the terminal guidance control strategy in the two-dimensional plane, the time-coordinated terminal guidance control strategy of the UAV cluster in the three-dimensional space is obtained, which is specifically: Convert the angular velocity of the drone's line of sight in three-dimensional space to the drone's body coordinate system: In the formula, , Indicates i The longitudinal and lateral components of the current line of sight angular velocity of the drone in the drone body coordinate system, For the i The pitch angle of the drone, , , For the i The three-axis components of the current line of sight angular velocity of the drone in three-dimensional space; In order to achieve the time coordination of the terminal guidance process in three-dimensional space, the terminal guidance control strategy in the two-dimensional plane is used to adjust the UAV in the horizontal direction, and the proportional guidance law is used to adjust the UAV in the vertical direction. Therefore, the time coordinated terminal guidance control strategy of the UAV cluster in three-dimensional space is obtained as follows: In the formula, For the i The lateral acceleration control command of the UAV at the current moment, is the maximum lateral acceleration of the UAV, For the i The longitudinal acceleration control command of the UAV at the current moment, is the maximum longitudinal acceleration of the UAV.

6. The segmented guidance method suitable for coordinated strike of multiple UAVs according to claim 5 is characterized in that: Real-time coordination during terminal guidance ;or is a constant value that satisfies the constraints.

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