Time-coordinated guidance control method considering speed limit of unmanned aerial vehicle

Abstract

The application discloses a time cooperative guidance control method considering speed limitation of an unmanned aerial vehicle, and comprises the following steps: obtaining the motion state information of a target in real time through an optoelectronic pod carried on the unmanned aerial vehicle; obtaining the speed and acceleration of the target in real time according to the motion state information of the target; obtaining the acceleration instruction of the unmanned aerial vehicle in real time according to the expected attack time, the relative distance, the motion information of the target and the speed limitation of the unmanned aerial vehicle itself; and controlling the unmanned aerial vehicle to fly according to the obtained acceleration instruction of the unmanned aerial vehicle. The time cooperative guidance control method considering the speed limitation of the unmanned aerial vehicle can realize omnidirectional saturated attack on an arbitrary motion target under the speed constraint condition of the unmanned aerial vehicle.

Description

Time-coordinated guidance and control method considering the speed limit of unmanned aerial vehicles Technical Field

[0001] This invention relates to a time-coordinated guidance and control method that takes into account the speed limitations of unmanned aerial vehicles, and belongs to the field of aircraft guidance and control technology. Background Technology

[0002] Saturation attack refers to unmanned aerial vehicles (UAVs) launching from different directions and hitting the target simultaneously. Saturation attack can greatly improve the ability of UAVs to penetrate defense layers.

[0003] To achieve saturation attacks, i.e., mission requirements involving simultaneous hits on targets, it is necessary to adjust and constrain the execution time of unmanned aerial vehicles (UAVs). However, traditional guidance laws can only ensure the UAV hits the target, without constraining the entire timeframe. Therefore, time-coordinated guidance laws emerged, which are guidance laws that can constrain flight time while still ensuring target hits. Currently, there are two main methods for time-coordinated guidance laws: open-loop cooperative guidance control and closed-loop cooperative guidance control.

[0004] The closed-loop cooperative guidance and control method is a time-coordinated guidance and control approach that relies entirely on the communication network between the various UAVs to achieve simultaneous attacks without requiring pre-setting attack times. During flight, each UAV communicates with the others, exchanging its flight status information in real time and comparing it with the flight status of other UAVs to adjust its own state, thereby achieving the effect of simultaneous attack. However, this guidance and control method heavily relies on communication equipment. If the communication network is attacked or vulnerabilities are found, the entire UAV swarm will collapse, causing severe losses. It is difficult to implement in engineering, has low fault tolerance, and its application is limited.

[0005] Open-loop cooperative guidance and control methods were initially proposed for missiles whose velocity cannot be changed. These control methods require pre-setting the expected attack time. For missiles with unchangeable velocity, the only way to achieve simultaneous strikes is by changing their trajectory, which often has many limitations in practical operation.

[0006] Currently, unmanned aerial vehicles (UAVs) generally use open-loop cooperative guidance and control methods to achieve saturation attacks. However, for UAVs with variable speeds, using open-loop cooperative guidance and control methods that change flight trajectories would result in energy waste and would fail to leverage the advantages of variable speeds.

[0007] For the reasons mentioned above, the inventors have conducted in-depth research on existing open-loop cooperative guidance and control methods in order to propose a time-cooperative guidance method for variable-speed unmanned aerial vehicles that can take into account their own speed constraints. Summary of the Invention

[0008] To overcome the above problems, the inventors conducted in-depth research and designed a time-coordinated guidance and control method that considers the speed limitations of unmanned aerial vehicles. This method includes the following steps:

[0009] S1. The target's motion state information is obtained in real time through an electro-optical pod carried on the unmanned aerial vehicle (UAV). The target's motion state information includes the line-of-sight angle q of the target relative to the pitch direction of the UAV. y The line-of-sight angle q of the target relative to the yaw direction of the UAV z , and the distance R of the target relative to the unmanned aerial vehicle;

[0010] S2. Obtain the target's velocity and acceleration in real time based on the target's motion state information;

[0011] S3. Based on the expected attack time, relative distance, target motion information, and the speed limit of the UAV itself, obtain the acceleration command of the UAV in real time;

[0012] S4. Control the flight of the unmanned aerial vehicle according to the acceleration command obtained from the unmanned aerial vehicle.

[0013] In a preferred embodiment, before step S1, there is a step S0: taking pictures of the target using an electro-optical pod carried on the unmanned aerial vehicle to obtain continuous images containing the target; estimating the state of the target using the continuous images, and then calculating the angular rate control command for the rotation of the electro-optical pod to control the rotation of the electro-optical pod to achieve continuous tracking and observation of the target.

[0014] In a preferred embodiment, in step S3, the acceleration command includes a line-of-sight normal acceleration command and a line-of-sight radial acceleration command;

[0015] The obtained normal acceleration command is represented as:

[0016]

[0017] in, Indicates the normal acceleration command, V c Indicates the velocity of the target relative to the unmanned aerial vehicle; Ω Los This represents the target's line-of-sight rotation angular rate relative to the UAV; N represents the proportional guidance coefficient, a tn This represents the normal acceleration of the target in the inertial frame.

[0018] In a preferred embodiment, the obtained radial acceleration command is expressed as:

[0019]

[0020] Among them, a cx Let α represent the radial acceleration command of the unmanned aerial vehicle (UAV), α represent the velocity convergence coefficient, x1 represent the design state variable, and x1(t) represent the design state variable at time t; x2 represent the difference between the UAV's current approach velocity and its own velocity constraint minimum, and x2(t) represent the difference between the UAV's approach velocity and its own velocity constraint minimum at time t. tx This represents the normal acceleration of the target in the line-of-sight frame.

[0021] In a preferred embodiment, the state quantity x1 is obtained based on the speed limit of the unmanned aerial vehicle, the expected attack time, and the relative distance.

[0022] In a preferred embodiment

[0023] The state variable x1 is represented as:

[0024] x1=V c,min (t d -t)-R

[0025] Where V c,min t is the minimum value of the unmanned aerial vehicle's own speed constraint. d R represents the pre-set expected attack time and the current relative distance between the unmanned aerial vehicle and the target.

[0026] In a preferred embodiment, the difference x2 is represented as

[0027] x2=-V c,min +V c

[0028] Where V c,min V is the minimum value of the unmanned aerial vehicle's own speed constraint. c This indicates the speed of the target unmanned aerial vehicle (UAV) relative to the UAV.

[0029] In a preferred embodiment, the velocity convergence coefficient α is expressed as:

[0030]

[0031] Where x 2,max x1(0) represents the difference between the maximum and minimum values ​​of the unmanned aerial vehicle's own speed constraint, and x2(0) represents the difference between the unmanned aerial vehicle's initial approach speed and the minimum value of its own speed constraint.

[0032] In a preferred embodiment, in step S4, the acceleration command in the line-of-sight frame is converted to the inertial frame to control the unmanned aerial vehicle.

[0033] The acceleration command for the unmanned aerial vehicle in the inertial frame is expressed as follows:

[0034]

[0035] in, This represents the normal acceleration in the line-of-sight frame. This represents the tangential acceleration along the line of sight.

[0036] The coordinate rotation matrix from the line-of-sight frame to the inertial frame is represented as:

[0037]

[0038] In a preferred embodiment, the method further includes S5, when the distance R between the unmanned aerial vehicle and the target is less than a preset value R at a desired time. sp At that point, it is assumed that the unmanned aerial vehicle has successfully hit the target and guidance control is no longer required.

[0039] The beneficial effects of this invention include:

[0040] (1) The time-coordinated guidance and control method considering the speed limit of unmanned aerial vehicles provided by the present invention can estimate the target motion and perform autonomous navigation accordingly;

[0041] (2) The time-coordinated guidance and control method considering the speed limit of unmanned aerial vehicles provided by the present invention can quickly and stably track maneuvering targets in the shortest time, and enable unmanned aerial vehicles with different initial conditions and different speed constraints to hit the target at the expected attack time, thereby achieving all-round precision attack.

[0042] (3) The time-coordinated guidance and control method considering the speed limit of unmanned aerial vehicles provided by the present invention can achieve the effect of simultaneous arrival by changing the flight speed of unmanned aerial vehicles, which can better utilize the performance of unmanned aerial vehicles and avoid unnecessary energy waste.

[0043] (4) The time-coordinated guidance and control method considering the speed limit of unmanned aerial vehicles provided by the present invention enables unmanned aerial vehicles with flight speed limits to perform tasks with arbitrary desired strike time. Attached Figure Description

[0044] Figure 1 shows a flowchart of a time-coordinated guidance and control method considering the speed limit of an unmanned aerial vehicle according to a preferred embodiment of the present invention.

[0045] Figure 2 shows the motion trajectories of unmanned aerial vehicles and targets with different initial conditions in Example 1;

[0046] Figure 3 shows the change of the relative distance between the unmanned aerial vehicle and the target under different initial conditions in Example 1 over time;

[0047] Figure 4 shows the speed control curve of the unmanned aerial vehicle with a given speed limit in Example 1;

[0048] Figure 5 shows the speed control curves of the unmanned aerial vehicle with the same speed limit in Example 1 when setting different expected strike times. Detailed Implementation

[0049] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Through these descriptions, the features and advantages of the present invention will become clearer and more apparent.

[0050] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments. Although various aspects of embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated otherwise.

[0051] According to the present invention, a time-coordinated guidance and control method considering the speed limit of an unmanned aerial vehicle is provided, as shown in Figure 1. The method includes the following steps:

[0052] S1. The target's motion state information is obtained in real time through an electro-optical pod carried on the unmanned aerial vehicle (UAV). The target's motion state information includes the line-of-sight angle q of the target relative to the pitch direction of the UAV. y The line-of-sight angle q of the target relative to the yaw direction of the UAV z , and the distance R of the target relative to the unmanned aerial vehicle;

[0053] S2. Obtain the target's velocity and acceleration in real time based on the target's motion state information;

[0054] S3. Based on the expected attack time, relative distance, target motion information, and the speed limit of the UAV itself, obtain the acceleration command of the UAV in real time;

[0055] S4. Control the flight of the unmanned aerial vehicle according to the acceleration command obtained from the unmanned aerial vehicle.

[0056] Preferably, the unmanned aerial vehicle is selected as a rotary-wing unmanned aerial vehicle, specifically a drone with four or more rotors; the real-time acceleration command is input to the rotor control system of the unmanned aerial vehicle, and the rotor control system can adjust the rotor speed according to the input acceleration command. The change in speed causes the rotor lift to change, thereby controlling the attitude and position of the unmanned aerial vehicle.

[0057] According to the present invention, the optoelectronic pod can be any existing optoelectronic pod, as long as it can perform target tracking and output the line-of-sight angle and line-of-sight angular rate of the target relative to the unmanned aerial vehicle.

[0058] In this invention, the velocity, position, and acceleration information of the target refer to velocity and position information in an inertial frame. This inertial frame is defined with the UAV's center of mass as the origin, geographical east as the x-axis, geographical north as the y-axis, and the z-axis perpendicular to the x and y axes, with upward being positive, conforming to the right-hand rule. The line-of-sight frame is defined with the UAV's center of mass as the origin, and the direction of the line connecting the UAV and the target as the x-axis. L Axis, Z L The axis is perpendicular to X in the vertical plane. L The axis, pointing upwards is positive, Y L The axis is determined by the right-hand rule.

[0059] Furthermore, before step S1, there is also step S0: taking pictures of the target using the electro-optical pod carried on the unmanned aerial vehicle to obtain continuous images containing the target; estimating the state of the target using the continuous images, and then calculating the angular rate control command for the rotation of the electro-optical pod to control the rotation of the electro-optical pod to achieve continuous tracking and observation of the target.

[0060] Preferably, state estimation is performed through machine vision algorithm processing. Any known visual recognition and tracking algorithm can be used by those skilled in the art, and no limitation is made in this invention.

[0061] In step S2, the velocity and acceleration components of the target can be obtained by any existing target state estimation method, including but not limited to machine vision algorithm processing, radar detection, laser detection, etc., and are not particularly limited in this invention.

[0062] According to a preferred embodiment of the present invention, in step S3, the acceleration command includes a line-of-sight normal acceleration command and a line-of-sight radial acceleration command;

[0063] In this invention, the acceleration command is decoupled and decomposed into the normal direction and the radial direction. This satisfies the positional constraint of hitting the target in the normal channel and considers the time constraint control of the actual flight speed limit of the UAV in the radial channel. In this way, the time constraint of hitting the target simultaneously can be achieved by changing the speed of the UAV.

[0064] Furthermore, the obtained normal acceleration command is represented as:

[0065]

[0066] in, Indicates the normal acceleration command, Vc Indicates the velocity of the target relative to the unmanned aerial vehicle; Ω Los The target's line-of-sight rotation angular rate relative to the UAV is represented by the value of α, which is obtained in real time through an electro-optical pod carried by the UAV; N represents the proportional guidance coefficient, which takes a value of 3 to 5, preferably 3; a tn This represents the normal acceleration of the target in the inertial frame.

[0067] In a preferred embodiment, the obtained radial acceleration command is expressed as:

[0068]

[0069] Among them, a cx The radial acceleration command of the unmanned aerial vehicle (UAV) is represented by α, the velocity convergence coefficient is represented by x1, the state variable is represented by x2, the difference between the UAV's current approach velocity and its own velocity constraint minimum is represented by t, and the flight time of the UAV is represented by a. tx This represents the normal acceleration of the target in the line-of-sight frame.

[0070] In a preferred embodiment, the state quantity x1 is obtained based on the speed limit of the unmanned aerial vehicle, the expected attack time, and the relative distance.

[0071] More preferably, the state variable x1 is represented as:

[0072] x1=V c,min (t d -t)-R (III)

[0073] Where V c,min t is the minimum value of the unmanned aerial vehicle's own speed constraint. d R represents the pre-set expected attack time and the current relative distance between the unmanned aerial vehicle and the target.

[0074] Preferably, the difference x2 is represented as

[0075] x2=-V c,min +V c (Four)

[0076] Where V c,min V is the minimum value of the unmanned aerial vehicle's own speed constraint. c This indicates the speed of the target unmanned aerial vehicle (UAV) relative to the UAV.

[0077] According to a preferred embodiment of the present invention, the velocity convergence coefficient α is expressed as:

[0078]

[0079] Where x 2,max x1(0) represents the difference between the maximum and minimum values ​​of the unmanned aerial vehicle's own speed constraint, and x2(0) represents the difference between the unmanned aerial vehicle's initial approach speed and the minimum value of its own speed constraint.

[0080] In S4, acceleration commands from the line-of-sight frame are converted to those from the inertial frame, thereby enabling control of the unmanned aerial vehicle.

[0081] The acceleration command for the unmanned aerial vehicle in the inertial frame is expressed as follows:

[0082]

[0083] in, This represents the normal acceleration in the line-of-sight frame, which is perpendicular to the line connecting the target and the aircraft. This represents the normal acceleration in the line-of-sight frame, which is perpendicular to the line connecting the target and the aircraft.

[0084] The coordinate rotation matrix from the line-of-sight frame to the inertial frame is represented as:

[0085]

[0086] In a preferred embodiment, the method further includes S5, when the distance R between the unmanned aerial vehicle and the target is less than a preset value R at a desired time. sp When the drone is considered to have successfully hit the target, that is, hit the target at the expected time, guidance and control will no longer be performed.

[0087] The preset value R sp Select the setting based on the size of the target; generally, it is set to 0.2 meters.

[0088] Example

[0089] Example 1

[0090] Simulation experiments were conducted, in which...

[0091] The initial position of the target (x) t0 ,y t0 ) = (160, 120)m;

[0092] The initial velocity of the target (V) xt0 Vy t0 ) = (0,0) m / s;

[0093] The target is performing three-dimensional maneuvers in the air, and its acceleration in the inertial frame is shown in the following equation:

[0094]

[0095] The initial positions and initial velocities of each unmanned aerial vehicle are shown in the table below.

[0096] Initial position (m) Initial velocity (m / s) UAV1(0,0)(4,1.3) UAV2(40,60)(4.1,0.6) surface

[0097] The expected attack time is set to 16 seconds, and the speed of the unmanned aerial vehicle (UAV) is limited to 5 m / s to 20 m / s. The target is tracked by an electro-optical pod, and the guidance commands of the UAV are calculated in real time using the following formulas (I) and (II):

[0098]

[0099]

[0100] Where N takes the value of 3, Ω Los Output is provided in real time by the photoelectric pod;

[0101] x1=V c,min (t d -t)-R (III)

[0102] x2=-V c,min +V c (Four)

[0103]

[0104] The acceleration commands from the line-of-sight frame are converted to the inertial frame to control the unmanned aerial vehicle.

[0105] The acceleration command for the unmanned aerial vehicle in the inertial frame is expressed as follows:

[0106]

[0107]

[0108] The unmanned aerial vehicle (UAV) is controlled to track the target via guidance commands. During the target tracking process:

[0109] Figure 2 shows the trajectories of two unmanned aerial vehicles (UAVs) and a target with different initial conditions. As can be seen from Figure 2, the two UAVs were able to successfully reach the maneuvering target position simultaneously from different directions.

[0110] Figure 3 shows the change in the relative distance between two unmanned aerial vehicles (UAVs) with different initial conditions and the target over time. Combining Figures 2 and 3, it can be seen that for two UAVs with different initial positions and speeds, their remaining flight time can be made to converge relatively quickly, that is, to hit the maneuvering target at the expected attack time.

[0111] Figure 4 shows the speed control curves of the unmanned aerial vehicles (UAVs) under a given speed limit. As can be seen from Figure 4, both UAVs can meet their own speed limits while simultaneously achieving their mission objectives.

[0112] Figure 5 shows the speed control curves of unmanned aerial vehicles with the same speed limit when setting different expected attack times. As can be seen from Figure 5, both unmanned aerial vehicles can reach the target position at any expected attack time while meeting the speed limit by changing the speed convergence coefficient.

[0113] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "front," and "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship in the working state of this invention, and are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. Furthermore, the terms "first," "second," "third," and "fourth" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0114] The present invention has been described above with reference to preferred embodiments; however, these embodiments are merely exemplary and illustrative. Various substitutions and modifications can be made to the present invention based on these embodiments, all of which fall within the scope of protection of the present invention.

Claims

1. A time-coordinated guidance and control method considering the speed limitations of unmanned aerial vehicles, characterized in that, The method includes the following steps: S1, obtaining the target's motion state information in real time through an electro-optical pod carried on the unmanned aerial vehicle, wherein the target's motion state information includes the line-of-sight angle of the target relative to the pitch direction of the unmanned aerial vehicle. The line-of-sight angle of the target relative to the yaw direction of the UAV and the distance of the target relative to the unmanned aerial vehicle S2. Obtain the target's velocity and acceleration in real time based on the target's motion state information; S3. Obtain the UAV's acceleration command in real time based on the expected attack time, relative distance, target motion information, and the UAV's own speed limit; S4. Control the UAV's flight according to the obtained UAV acceleration command; In step S3, the acceleration command includes a line-of-sight normal acceleration command and a line-of-sight radial acceleration command; the obtained normal acceleration command is expressed as: ,in, Indicates normal acceleration command, This indicates the target's velocity relative to the unmanned aerial vehicle; This represents the angular rate of rotation of the target relative to the line of sight of the unmanned aerial vehicle; The coefficient representing proportional guidance. This represents the target's normal acceleration in the inertial frame; the obtained radial acceleration command is expressed as: ,in, This indicates the radial acceleration command for the unmanned aerial vehicle. Indicates the velocity convergence coefficient. Indicates design state variables. express Design state variables at any given moment; This represents the difference between the current approach speed of the unmanned aerial vehicle and its own speed constraint minimum value. Indicates unmanned aerial vehicle The difference between the approach velocity at time and the minimum value of its own velocity constraint. This represents the target's normal acceleration in the line-of-sight frame. In step S4, the acceleration command in the line-of-sight frame is converted to the inertial frame to control the unmanned aerial vehicle (UAV). The acceleration command for the UAV in the inertial frame is... Represented as: ,in, This represents the normal acceleration in the line-of-sight frame. This represents the tangential acceleration in the line-of-sight frame. The coordinate rotation matrix from the line-of-sight frame to the inertial frame is represented as: 。 2. The time-coordinated guidance and control method considering the speed limit of an unmanned aerial vehicle according to claim 1, characterized in that, The state quantity This is obtained based on the speed limit of the unmanned aerial vehicle, the expected attack time, and the relative distance.

3. The time-coordinated guidance and control method considering the speed limit of an unmanned aerial vehicle according to claim 2, characterized in that, The state quantity Represented as: ,in This represents the minimum value constrained by the unmanned aerial vehicle's own speed. The expected attack time is pre-set. This indicates the relative distance between the unmanned aerial vehicle and the target.

4. The time-coordinated guidance and control method considering the speed limit of an unmanned aerial vehicle according to claim 1, characterized in that, The difference Represented as ,in This represents the minimum value constrained by the unmanned aerial vehicle's own speed. This indicates the speed of the target unmanned aerial vehicle (UAV) relative to the UAV.

5. The time-coordinated guidance and control method considering the speed limit of an unmanned aerial vehicle according to claim 1, characterized in that, velocity convergence coefficient Represented as: ,in This represents the difference between the maximum and minimum values ​​of the unmanned aerial vehicle's own speed constraint. Represents the state quantity at the initial moment; This represents the difference between the initial approach velocity of the unmanned aerial vehicle and its own velocity constraint minimum.

6. The time-coordinated guidance and control method considering the speed limit of an unmanned aerial vehicle according to claim 1, characterized in that, The method also includes S5, when the distance between the unmanned aerial vehicle and the target The expected time is less than the preset value. At that point, it is assumed that the unmanned aerial vehicle has successfully hit the target and guidance control is no longer required.

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