A time-coordinated control method for a variable speed aircraft

Abstract

The application discloses a time coordination control method and system of a variable-speed aircraft. The method provided by the application adjusts the guidance law of each aircraft according to the relative motion state of the target and each aircraft in the flight process of the multiple aircrafts, so that the multiple aircrafts strike the target at the same time. The application can make the aircrafts with different initial conditions hit the target at the expected attack time, realize all-around accurate attack, change the flight speed of the aircrafts to reach the target at the same time, better exert the performance of the aircrafts, and avoid unnecessary energy waste.

Description

Technical Field

[0001] This invention relates to the field of aircraft control technology, and in particular to a time-coordinated control method and system for a variable-speed aircraft. Background Technology

[0002] Aircraft are gradually appearing in information-based and unmanned warfare due to their low cost and flexible configuration.

[0003] Currently, there are two main types of guidance methods for achieving simultaneous hits on a single target by multiple aircraft: open-loop cooperative guidance and closed-loop cooperative guidance.

[0004] Open-loop cooperative guidance methods were initially developed for missiles with uncontrollable speeds, and could only constrain the attack time by changing the flight trajectory. For aircraft with variable speeds, this approach cannot utilize the aircraft's optimal performance, resulting in unnecessary energy loss. While some open-loop cooperative guidance methods can be applied to variable-speed aircraft, the targets are all stationary, making it impossible to coordinate attacks on maneuvering targets, thus limiting their application scenarios.

[0005] Closed-loop cooperative guidance methods do not require pre-planned attack timing. Instead, they exchange information in real-time via a communication network during flight, adjusting their own state based on the status of other aircraft in the swarm to generate corresponding control commands and achieve a simultaneous hit. However, the communication network of closed-loop cooperative methods is susceptible to interference, and communication disruptions can prevent real-time information exchange. Furthermore, if one aircraft fails, the entire swarm can become uncontrollable. This cooperative guidance method places high demands on the communication network's anti-interference capabilities, has low fault tolerance, and suffers significant losses, making it difficult to apply in engineering. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention proposes a time-coordinated control method and system for variable-speed aircraft.

[0007] To achieve the above objectives, in a first aspect, the present invention provides a time-coordinated control method for variable-speed aircraft, which utilizes the real-time adjustment of the guidance law of each aircraft based on the relative motion state between the target and each aircraft during the flight of multiple aircraft, so that multiple aircraft can strike the target simultaneously.

[0008] Secondly, the present invention provides a time-coordinated control system for a variable-speed aircraft. The system includes:

[0009] The status acquisition module is used to acquire the target's velocity and acceleration in real time;

[0010] a guidance law obtaining module, configured to obtain a guidance law of each aircraft in real time according to a desired attack time, an acceleration of the target, and motion information of the target relative to the aircraft, wherein the motion information comprises a distance, a speed, a line-of-sight angle, and a line-of-sight angle rate;

[0011] an executing module, configured to control the multiple aircrafts to attack the target at the desired attack time through the guidance law of each aircraft.

[0012] The time coordination control method and system of the variable-speed aircraft provided by the application have the following beneficial effects:

[0013] (1) The method provided by the application detects and tracks the target through the image acquisition device and the photoelectric pod, and has high precision, strong intuitiveness, low cost, and is not affected by clutter interference, compared with radar and space-based platforms.

[0014] (2) The method provided by the application can estimate the motion of the target and autonomously navigate accordingly; in combination with a flexible guidance law, the method can quickly and stably track a maneuvering target in the shortest time, and enables each aircraft with different initial conditions to hit the target at the desired attack time, thereby achieving all-around accurate attack; and the method can also achieve simultaneous hitting of the target by changing the flight speed of the aircraft, thereby better exerting the performance of the aircraft and avoiding unnecessary energy waste.

[0015] (3) The method provided by the application divides the guidance law into a normal acceleration instruction and a radial acceleration instruction, respectively implements position constraint and time constraint, ensures that the aircraft hits a target in any motion state at the desired attack time, thereby meeting the task requirements of coordinated attack of multiple aircrafts, and realizes all-around autonomous operation and simultaneous and accurate all-around saturated attack on a maneuvering target. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 a flowchart of a time coordination control method of a variable-speed aircraft according to the application is shown;

[0017] Figure 2 a structural schematic diagram of a time coordination control system of a variable-speed aircraft according to the application is shown;

[0018] Figure 3 a schematic diagram of motion trajectories of four aircrafts with different initial conditions and a target in embodiment 1 of the application is shown;

[0019] Figure 4 a schematic diagram of changes of distances of four targets with different initial conditions relative to the aircrafts with time in embodiment 1 of the application is shown;

[0020] Figure 5Fig. 1 shows a schematic diagram of the residual flight time of four aircrafts with different initial conditions in Embodiment 1 of the present application varying with time;

[0021] Figure 6 Fig. 2 shows a schematic diagram of the acceleration control instructions of the four aircrafts with different initial conditions in Embodiment 1 of the present application in three directions of the inertial coordinate system (north-east sky).

[0022] Figure 7 Fig. 3 shows a schematic diagram of the speed control curve of the four aircrafts with different initial conditions in Embodiment 1 of the present application. DETAILED DESCRIPTION

[0023] The preferred embodiments of the present application will be described in detail below with reference to the accompanying drawings, so that the advantages and features of the present application can be more easily understood by those skilled in the art, and the scope of protection of the present application can be more clearly defined.

[0024] It should be noted that, in this document, the terms "comprising", "containing", or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or further includes elements inherent to such a process, method, article, or device. Without more limitations, the elements defined by the statement "comprising" do not exclude the presence of additional identical elements in the process, method, article, or device including the elements.

[0025] At present, the open-loop cooperative guidance method cannot exert the optimal performance of the variable-speed aircraft, resulting in unnecessary energy loss. Although the partial open-loop cooperative guidance method can be applied to the variable-speed aircraft, the attacked objects are all stationary targets, which cannot achieve cooperative attack on mobile targets, and the application scenarios are limited.

[0026] In order to solve the above problems, the present application provides a time cooperative control method for a variable-speed aircraft. The method adjusts the guidance law of each aircraft in real time according to the relative motion state of the target and each aircraft during the flight of the multiple aircrafts, so that the multiple aircrafts attack the target at the same time. The present application further improves the open-loop cooperative guidance, realizes autonomous operation throughout the whole process, and performs simultaneous and accurate omnidirectional saturated attack on the mobile target.

[0027] Specifically, the time cooperative control method for a variable-speed aircraft provided by the present application, as shown in Fig. 1, mainly includes the following steps: Figure 1

[0028] S101, acquiring the speed and acceleration of the target in real time.

[0029] Preferably, before step S101, the method can further include: ​

[0030] S100-1, obtaining multiple images containing the target. For example, each aircraft carries an image acquisition device (such as a camera, etc.), and the image acquisition device is used to continuously capture the target.

[0031] In the present application, the aircraft is preferably a rotor unmanned aerial vehicle or a fixed-wing unmanned aerial vehicle, and more preferably a rotor unmanned aerial vehicle with four or more propellers.

[0032] By inputting the real-time obtained guidance law into the rotor control system of the aircraft, the rotor control system can adjust the rotor propeller speed according to the input guidance law, and the speed change causes the rotor lift to change, thereby controlling the attitude and position of the aircraft.

[0033] It is worth noting that the present application does not make specific restrictions on the form of the target, and objects that make maneuvering movements can become the target of the present application. For example, the target can be a moving object on the ground, or a flying aircraft to be attacked.

[0034] S100-2, obtaining the motion information of the target relative to the aircraft in real time according to the multiple images containing the target, so as to realize continuous tracking of the target, wherein the motion information includes the line-of-sight angle q y of the target relative to the pitch direction of the aircraft, the line-of-sight angle q z of the target relative to the yaw direction of the aircraft, and the distance R of the target relative to the aircraft.

[0035] In the present application, each aircraft obtains multiple images containing the target, each aircraft can obtain the motion information of the target, and uses Kalman filtering algorithm to predict the state of the target, and controls the photoelectric pod carried on each aircraft to continuously observe and track the target according to the predicted state of the target.

[0036] Preferably, the photoelectric pod can be selected from the existing photoelectric pods in the art, which can perform target tracking and output the line-of-sight angle and line-of-sight angle rate of the target relative to the aircraft.

[0037] For example, the state prediction process of the target can be represented by the following formula:

[0038]

[0039] wherein,

[0040] state quantity

[0041] measurement quantity

[0042] K k represents the gain value;

[0043] Δx, Δy, Δz represent three distance components of the target relative to the aircraft in the inertial coordinate system; V tx ,V ty ,V tz represent three velocity components of the target in the inertial coordinate system; a tx ,a ty ,a tz represent three acceleration components of the target in the inertial coordinate system; V mx ,V my ,V mz represent three velocity components of the aircraft in the inertial coordinate system;

[0044] represent state quantities at the k moment; the predicted value is obtained by the following formula

[0045]

[0046] wherein a mx , a my , a mz represent three acceleration components of the aircraft in the inertial coordinate system;

[0047] represent state equations.

[0048] Preferably, the motion information further comprises the velocity V c of the target relative to the aircraft, and the line-of-sight angular rate Ω Los of the target relative to the aircraft.

[0049] In the present application, the velocity, position and acceleration of the target are all based on the inertial coordinate system.

[0050] wherein the inertial coordinate system refers to taking the mass center of the aircraft as the origin, the geographical east direction as the x axis, the geographical north direction as the y axis, the z axis being perpendicular to the x and y axes and upward as positive, constituting the right-hand rule.

[0051] The line-of-sight coordinate system refers to taking the mass center of the aircraft as the origin, the connecting line direction of the aircraft and the target as the X L axis, the Z L axis being perpendicular to the X L axis in the vertical plane and upward as positive, the Y L axis being determined through the right-hand rule.

[0052] In the present application, the target is detected and tracked by the image acquisition device and the photoelectric pod, and compared with the radar and the space-based platform, the precision is high, the intuitiveness is strong, the cost is low, and the influence of clutter interference is avoided.

[0053] S102, obtaining the guidance law of each aircraft in real time according to the expected attack time, the acceleration of the target, and the motion information of the target relative to the aircraft, wherein the motion information comprises distance, speed, line-of-sight angle, and line-of-sight angle rate.

[0054] In the application, the guidance law comprises a normal acceleration instruction and a radial acceleration instruction.

[0055] The normal acceleration instruction corresponds to a position constraint, i.e., the relative distance between the target and the aircraft is zero when the target is hit; and the radial acceleration instruction corresponds to a time constraint, i.e., the flight speed of the aircraft is controlled so that the aircraft attacks the target at the expected time.

[0056] In the application, the position and the time are simultaneously constrained in the guidance law, so that the aircraft hits the target in any motion state at the expected attack time, thereby meeting the task requirement of multi-aircraft cooperative attack.

[0057] Preferably, the normal acceleration instruction can be represented by Formula I:

[0058]

[0059] wherein a c represents the normal acceleration instruction;

[0060] represents a conversion matrix from the line-of-sight coordinate system to the inertial coordinate system;

[0061] N represents a proportional guidance rate, and N is preferably 3-5, more preferably 3; when N is in the above range, the overload limit of the aircraft can be met;

[0062] V c represents the speed of the target relative to the aircraft, i.e., the difference between the speed of the target and the projection of the speed of the aircraft in the line-of-sight direction;

[0063] Ω Los represents the line-of-sight angle rate of the target relative to the aircraft, i.e., the rotation rate of the angle between the line connecting the aircraft and the target and the X axis of the inertial coordinate system, and the component can be represented as and Ω Los can be output in real time by an optical pod;

[0064] a tn represents the normal acceleration of the target in the inertial coordinate system, and the value can be the square of the speed of the target divided by the radius of the trajectory of the target.

[0065] Specifically, the coordinate rotation matrix of the line-of-sight coordinate system to the inertial coordinate system can be represented according to Formula II:

[0066]

[0067] It is found that the normal acceleration command as shown in Formula One requires the least energy for the aircraft when attacking a maneuvering target.

[0068] Preferably, the radial acceleration command can be represented by Formula Three:

[0069]

[0070] wherein a cx represents the radial acceleration command; represents a sliding mode reaching law; R represents the distance of the target relative to the aircraft, t dgo represents the desired remaining flight time, i.e. the difference between the desired flight time and the current time; a tx represents the radial acceleration of the target in the inertial coordinate system, which can be the derivative of the target speed with respect to time.

[0071] It is found that the radial acceleration command as shown in Formula Three is more stable and can make the deviation between the actual speed and the desired speed quickly converge to zero.

[0072] In order to accelerate the convergence speed and reduce chattering, more preferably, the sliding mode reaching law can be represented by Formula Four:

[0073]

[0074] wherein s represents a sliding surface, which is related to the time constraint; ε and m respectively represent a proportional coefficient and a power coefficient; sgn() represents a sign function.

[0075] wherein ε is greater than 0, and m is 0 to 1. It is found that when ε is 0.8 and m is 0.5, the rapidity and stability of convergence can be ensured, and the radial acceleration command limit of the aircraft can also be met.

[0076] Further preferably, the sliding surface s can be represented by Formula Five:

[0077] s = α (V d -V c ) Formula Five

[0078] wherein α represents a proportional coefficient, and the value range of α is preferably 0.4-1, and more preferably 0.6, so that the sliding surface is more stable and singularity does not occur;

[0079] V d represents the desired relative speed,

[0080] wherein the sliding surface as shown in Formula Five is simple and intuitive, and can avoid deviation when the state corresponding to the sliding surface is reached.

[0081] S103. By using the guidance law of each aircraft, control multiple aircraft to attack the target at the desired attack time.

[0082] In this invention, after multiple aircraft are launched from different locations, the aircraft adjust their respective flight speeds in real time based on the motion information between themselves and the target, thereby changing their guidance laws and achieving coordinated strikes against maneuvering targets.

[0083] In this invention, the guidance law is divided into normal acceleration command and radial acceleration command, which respectively realize position constraint and time constraint, so that each aircraft with different initial conditions can hit the target in any motion state at the expected attack time, thus achieving all-round precision attack.

[0084] Preferably, the mission is considered successful when the distance between the aircraft and the target is less than or equal to a preset value within the expected attack time, meaning the aircraft accurately hits the target.

[0085] Among them, the preset value R sp Select the settings based on the target size; if the target is large, then R... sp It can be set to a smaller value, such as 0.05 to 0.3 meters. If the target is larger, then R... sp It can be set to a larger value, such as 0.2 to 0.4 meters. R is preferred. sp The accuracy is 0.2 meters, which ensures that the aircraft can determine whether it has hit the target regardless of the target size.

[0086] This invention can estimate the motion state of a target and perform autonomous navigation accordingly; combined with a flexible strike execution system, it can quickly and stably track non-cooperative maneuvering targets in the shortest possible time, and enable multiple aircraft with different initial conditions to hit the target at the expected attack time, achieving all-round precision attack.

[0087] Secondly, the present invention also provides a time-coordinated control system for variable-speed aircraft. This system controls multiple aircraft to change their respective guidance laws according to their own and the target's states during flight, so that multiple aircraft can strike the target simultaneously.

[0088] Specifically, such as Figure 2 As shown, the system mainly includes:

[0089] The status acquisition module 201 is used to acquire the target's velocity and acceleration in real time.

[0090] The guidance law acquisition module 202 is used to acquire the guidance law of each aircraft in real time based on the expected attack time, the target's acceleration, and the target's motion information relative to the aircraft. The motion information includes distance, speed, line-of-sight angle, and line-of-sight angular rate.

[0091] An execution module 203 for controlling the multi-aircraft to attack the target at the desired attack time through the guidance law of each aircraft.

[0092] The time coordination control system of the variable-speed aircraft provided by the present application can be used to implement the time coordination control method of the variable-speed aircraft described in the first aspect, and has similar implementation principles and technical effects, which will not be described here.

[0093] Preferably, each module in the time coordination control system of the variable-speed aircraft can be directly in hardware (such as NX or TX2), in a software module executed by a processor, or a combination of both.

[0094] Embodiments

[0095] Example 1

[0096] An emulation experiment is set up, and four aircrafts are set up to attack the target in coordination. The initial position (x t0 ,y t0 ,z t0 ) of the target is (400, 300, 200) m, the initial speed (V xt0 ,V yt0 ,V zt0 ) is (3, 3, 5) m / s, the target makes a three-dimensional maneuvering motion in the air, and the acceleration in the inertial coordinate system is as follows:

[0097]

[0098] The initial parameters of the four aircrafts are shown in Table 1.

[0099] Table 1

[0100] Aircraft Initial position (m) Initial velocity (m / s) UAV1 (0,0,0) (8,8,5) UAV2 (800,600,0) (-8,-5,6) UAV3 (0,600,100) (8,-6,8) UAV4 (800,0,0) (-6,-6,3)

[0101] Each aircraft obtains the motion information of the target and continuously tracks the target using an electro-optical pod, wherein the motion information includes the line-of-sight angle q y of the target relative to the pitch direction of the aircraft, the line-of-sight angle q z of the target relative to the yaw direction of the aircraft, and the distance R of the target relative to the aircraft.

[0102] According to the desired attack time, the acceleration of the target, and the motion information of the target relative to the aircraft, the guidance law of each aircraft is obtained in real time, wherein the motion information includes the distance, the speed, the line-of-sight angle, and the line-of-sight angle rate.

[0103] The guidance law includes the normal acceleration command and the radial acceleration command.

[0104] In particular, the normal acceleration command is represented by Equation 1:

[0105]

[0106] where a c represents the normal acceleration command; represents the transformation matrix from the line-of-sight coordinate system to the inertial coordinate system; V c represents the velocity of the target relative to the vehicle; Ω Los represents the line-of-sight angular rate of the target relative to the vehicle; N = 3; a tn represents the normal acceleration of the target in the inertial coordinate system.

[0107] is represented by Equation 2:

[0108]

[0109] q y represents the line-of-sight angle of the target relative to the vehicle in the pitch direction; q z represents the line-of-sight angle of the target relative to the vehicle in the yaw direction.

[0110] In particular, the radial acceleration command is represented by Equation 3:

[0111]

[0112] where a cx represents the radial acceleration command; represents the sliding mode reaching law; R represents the distance of the target relative to the vehicle, t dgo represents the desired remaining flight time, i.e., the difference between the desired flight time and the current time; a tx represents the radial acceleration of the target in the inertial coordinate system.

[0113] Further, the sliding mode reaching law is represented by Equation 4:

[0114]

[0115] where s represents the sliding surface; ε = 0.8; m = 0.5; sgn() represents the sign function.

[0116] Further, the sliding surface s is represented by Equation 5:

[0117] s = a(V d - V c ) Equation 5

[0118] where a = 0.6; V d represents the desired relative velocity,

[0119] The multi-aircrafts attack the target at the desired attack time by the guidance law of each aircraft. The specific simulation results of the aircrafts are shown in Figures 3-7 .

[0120] As can be seen from Figure 3 , the embodiment can attack the mobile target simultaneously from all directions.

[0121] As can be seen from Figures 3-5 , the embodiment can make the residual flight time of the four aircrafts with different initial positions and initial speeds tend to be consistent quickly, i.e. hit the mobile target at the desired attack time, and the relative distance between each aircraft and the target at the desired attack time is less than 0.2m.

[0122] As can be seen from Figure 6 , the acceleration instruction of the embodiment is small, satisfying the overload limit of the aircraft.

[0123] As can be seen from Figure 7 , the embodiment can make the target relative speed V c of the target relative to the aircraft approach the desired relative speed V d , and keep them equal, thereby ensuring hitting the target at the desired attack time.

[0124] The present application has been described in detail with reference to specific embodiments and exemplary examples, but these descriptions are not to be construed as limiting the present application. Those skilled in the art understand that various equivalent substitutions, modifications or improvements can be made to the technical solutions and embodiments of the present application without departing from the spirit and scope of the present application, and these all fall within the scope of the present application.

Claims

1. A time-coordinated control method for a variable-speed aircraft, characterized in that, During the flight of multiple aircraft, the guidance law of each aircraft is adjusted in real time according to the relative motion state between the target and each aircraft, so that multiple aircraft can strike the target simultaneously. Includes the following steps: S101. Real-time acquisition of the target's velocity and acceleration; S102. Based on the expected attack time, the target's acceleration, and the target's motion information relative to the aircraft, the guidance law of each aircraft is acquired in real time, where the motion information includes distance, speed, line-of-sight angle, and line-of-sight angular rate. S103. By using the guidance law of each aircraft, control multiple aircraft to attack the target at the desired attack time; In step S102, the guidance law includes a normal acceleration command and a radial acceleration command; The normal acceleration command is expressed by Equation 1: Among them, a c Indicates normal acceleration command; The transformation matrix from the line-of-sight coordinate system to the inertial coordinate system is represented by N; the proportional guidance coefficient is represented by V. c Ω represents the velocity of the target relative to the aircraft. Los This represents the line-of-sight angular rate of the target relative to the aircraft; a tn This represents the normal acceleration of the target in the inertial coordinate system. Radial acceleration command is expressed by Equation 3: Among them, a cx Indicates radial acceleration command; Represents the sliding mode approach law; R represents the distance between the target and the aircraft, t dgo This represents the expected remaining flight time, which is the difference between the expected flight time and the current time; a tx This represents the radial acceleration of the target in the inertial coordinate system.

2. The time-coordinated control method for a variable-speed aircraft according to claim 1, characterized in that, Coordinate rotation matrix from line-of-sight coordinate system to inertial coordinate system Equation 2 represents: Where, q y The line-of-sight angle representing the target's pitch direction relative to the aircraft; q z This indicates the line-of-sight angle of the target relative to the yaw direction of the aircraft.

3. The time-coordinated control method for a variable-speed aircraft according to claim 1, characterized in that, Sliding mode approach law Equation 4 represents: Where s represents the sliding surface; ε and m represent the proportionality coefficient and the power coefficient, respectively; and sgn() represents the sign function.

4. The time-coordinated control method for a variable-speed aircraft according to claim 3, characterized in that, The sliding surface s is represented by Equation 5: s=α(V d -V c Formula 5 Where α represents the proportionality coefficient; V d This indicates the desired relative speed.

5. The time-coordinated control method for a variable-speed aircraft according to claim 4, characterized in that, The value of α ranges from 0.4 to 1.

6. The time-coordinated control method for a variable-speed aircraft according to claim 4, characterized in that, Expected relative speed

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