Terminal time constrained guidance method considering terminal acceleration convergence

Abstract

The application discloses a terminal time constraint guidance method considering terminal acceleration convergence, in which, flight is controlled by a proportional guidance law to ensure that a target position can be reached, and a bias guidance instruction is set to adjust the arrival time and terminal acceleration of the aircraft; a control scheme meeting the terminal acceleration convergence is set based on the optimal error dynamics thought, a control scheme meeting the terminal time constraint is set based on the prediction-correction method, the flight time error between the residual flight time and the expected flight time is fully considered, and the two are coupled to obtain the bias guidance instruction.

Description

Technical Field

[0001] This invention relates to aircraft guidance methods, and more particularly to a terminal time constraint guidance method that considers terminal acceleration convergence. Background Technology

[0002] When controlling multiple aircraft to fly towards a fixed target and ensuring their simultaneous arrival, a desired flight time can be preset for each aircraft based on factors such as takeoff time and distance, ensuring that the aircraft arrives at the target position precisely within that desired time. Furthermore, an excellent guidance system can eliminate both position and velocity pointing errors, ensuring acceleration convergence when the aircraft reaches the target position. This means that at the instant of approach to the target, the aircraft's velocity vector points precisely towards the target, or satisfies the terminal angle constraint, eliminating the need for additional lateral overload.

[0003] In practical engineering, there is no guidance scheme that can simultaneously satisfy terminal acceleration convergence and terminal time constraints. Based on this, the inventors have conducted in-depth research on guidance schemes for aircraft in order to design a new guidance method that can solve the above problems. Summary of the Invention

[0004] To overcome the above problems, the inventors conducted intensive research and designed a terminal time-constrained guidance method that considers terminal acceleration convergence. In this method, the flight is controlled by a proportional guidance law to ensure that the target position can be reached. Then, an offset guidance command is set to adjust the arrival time and terminal acceleration of the aircraft. Based on the idea of ​​optimal error dynamics, a control scheme that satisfies terminal acceleration convergence is set. Based on the prediction-correction method, the flight time error between the remaining flight time and the expected flight time is fully considered, and a control scheme that satisfies the terminal time constraint is set. The two are then coupled to obtain the offset guidance command, thus completing the present invention.

[0005] Specifically, the purpose of this invention is to provide a terminal time constraint guidance method that considers terminal acceleration convergence. In this method, before the launch of the aircraft, the desired flight time is stored in the aircraft. During the flight of the aircraft, control commands are given in real time to control the aircraft to reach the target position within the desired flight time. Upon reaching the target, the acceleration of the aircraft converges.

[0006] The beneficial effects of this invention include: (1) According to the terminal time constraint guidance method considering terminal acceleration convergence provided by the present invention, the method enables multiple aircraft at different locations and different take-off times to reach the target position simultaneously, thereby realizing the cooperative guidance of multiple aircraft. (2) According to the terminal time constraint guidance method considering terminal acceleration convergence provided by the present invention, the method enables the aircraft to converge acceleration before reaching the target position, that is, glide smoothly to the target position, and ensures that the attitude is controllable when reaching the target position. Attached Figure Description

[0007] Figure 1 This diagram illustrates the physical quantities related to the interception plane in this application. Figure 2 The image shows the aircraft trajectory curves under three different terminal time constraints in Embodiment 1 of this application; Figure 3 The diagram shows the zero-control miss distance versus time curves under three different terminal time constraints in Embodiment 1 of this application; Figure 4 The diagram shows the curves of terminal time error versus time under three different terminal time constraints in Embodiment 1 of this application. Figure 5 The figure shows the curves of the change between the estimated and actual values ​​of the remaining flight time under three different terminal time constraints in Embodiment 1 of this application. Detailed Implementation

[0008] 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.

[0009] 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.

[0010] According to the present invention, a terminal time-constrained guidance method considering terminal acceleration convergence is provided. In this method, a desired flight time is stored in the aircraft before launch. During flight, control commands are issued in real time to guide the aircraft to reach the target position within the desired flight time, and upon reaching the target, the aircraft's acceleration converges. Multiple aircraft can be used, each storing a specific desired flight time, thereby enabling multiple aircraft to reach the target position in a predetermined order or simultaneously.

[0011] In a preferred embodiment, the control command Obtained through the following formula (i): (one) in, This indicates a control command based on a proportional guidance law. This represents the navigation constant, which takes values ​​between 3 and 4. The speed of the aircraft is indicated by the GNSS signal receiver on the aircraft. This represents the navigation gain, which has a value of 3. Indicates time-of-flight error; This indicates the distance between the aircraft and the target, obtained through detection by the seeker on the aircraft; Indicates the leading angle; A unit vector representing control commands based on proportional guidance laws; This represents the ratio between the component of the bias guidance command perpendicular to the intercept plane and its component in the in-plane direction. This represents a unit vector perpendicular to the intercept plane.

[0012] The bias guidance command described in this application can be expressed as the following formula:

[0013] In this application, the interception plane is as follows: Figure 1 The image shown is made by and line-of-sight vector Zhang Cheng's plane; the aforementioned Indicates the direction of the aircraft's velocity vector, the A unit vector representing the direction of the aircraft's line of sight. Figure 1 middle express The terminal velocity unit vector of the aircraft under action, The unit vector representing the desired terminal velocity.

[0014] Preferably, the control command based on the proportional guidance law We obtain it through the following formula (II): (two) in, Indicates the angular velocity of line of sight rotation; It represents the direction of the aircraft's velocity vector. During the aircraft's flight, it can be obtained through combined navigation using an inertial navigation system and a GNSS receiver, and the results can be calculated in real time.

[0015] Preferably, the line-of-sight rotation angular velocity We obtain it through the following formula (iii): (three) in, The unit vector representing the direction of the aircraft's line of sight can be measured by the aircraft's radar guidance system during flight.

[0016] Preferably, the time-of-flight error We obtain it through the following formula (iv): (Four) in, Indicates the expected flight time; Indicates the remaining flight time; This indicates the current time, which is counted from the moment the aircraft takes off / launches; that is, the time is 0 at the moment of takeoff / launch.

[0017] Preferably, the remaining flight time We obtain it through the following formula (5): (five).

[0018] Preferably, the forward angle Obtained through the following formula (VI): (six).

[0019] In this application, the described Ensure that the line of sight is always within the field of view of the seeker head.

[0020] Preferably, the unit vector of the control command based on the proportional guidance law We obtain it through the following formula (VII): (seven).

[0021] Preferably, the unit vector perpendicular to the interception plane Obtained through the following formula (8): (eight).

[0022] Preferably, the ratio between the component of the bias guidance command perpendicular to the interception plane and its component in the in-plane direction is... Obtained under the following conditions: When the desired terminal angle is within the intercept plane, The value is 0. When the desired terminal angle is not within the interception plane, The value is 1; in this application, by setting this... Different values ​​of can allow the aircraft to adjust and control energy consumption according to specific mission requirements.

[0023] Example 1 The simulation is conducted, and the initial conditions are set as follows:

[0024] Given a navigation gain N = 3, the navigation constants are... =3, and the desired flight times are set to 40s, 45s, and 50s respectively. For each desired flight time, the following method is used to obtain control commands in real time and control the aircraft to fly towards the target: Control commands Obtained through the following formula (i): (one) in, Indicates the speed of the aircraft; Indicates the distance between the aircraft and the target; The control command based on the proportional guidance law We obtain it through the following formula (II): (two) in, Indicates the angular velocity of line of sight rotation; This indicates the direction of the aircraft's velocity vector.

[0025] The line of sight rotation angular velocity We obtain it through the following formula (iii): (three) in, A unit vector representing the direction of the aircraft's line of sight.

[0026] The time-of-flight error We obtain it through the following formula (iv): (Four) in, Indicates the expected flight time; Indicates the remaining flight time; Indicates the current time.

[0027] The remaining flight time We obtain it through the following formula (5): (five).

[0028] The forward angle Obtained through the following formula (VI): (six).

[0029] The unit vector of the control command based on the proportional guidance law We obtain it through the following formula (VII): (seven).

[0030] The unit vector perpendicular to the interception plane Obtained through the following formula (8): (eight).

[0031] The ratio between the component of the bias guidance command perpendicular to the intercept plane and its component in the in-plane direction. Obtained under the following conditions: When the desired terminal angle is within the intercept plane, The value is 0. When the desired terminal angle is not within the interception plane, The value is 1.

[0032] The simulation results obtained are as follows Figure 2 , Figure 3 , Figure 4 and Figure 5 As shown; Depend on Figure 2 It can be seen that under the three different terminal time constraints, the aircraft reaches the target within the expected flight time. Figure 3 , Figure 4 It can be seen that the zero-control miss distance and the terminal time error converge to 0 at the terminal moment, which proves the effectiveness of this guidance law.

[0033] Comparing the curves under different scenarios reveals that as the expected terminal time increases, the guidance command corresponding to the bias term increases, causing the aircraft to rapidly pitch up and perform additional maneuvers to increase altitude, thus lengthening the flight time and gradually converging the terminal time towards the expected value. Therefore, as the expected terminal time increases, the aircraft's trajectory becomes more curved; due to the increased command acceleration, the control energy also increases. Simultaneously, with the increase in flight time, due to the occurrence of additional maneuvers, the zero-control miss distance initially increases to meet the terminal time constraint, and then gradually converges to ensure a hit on the target.

[0034] Figure 5 This indicates that, after 25 seconds, the estimated remaining flight time... Compared with the true value This demonstrates that the terminal time-constrained guidance method considering terminal acceleration convergence provided in this application is selected... The estimation method and the accuracy of the corresponding guidance commands.

[0035] 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 terminal time-constrained guidance method considering terminal acceleration convergence, characterized in that, In this method, the desired flight time is stored in the aircraft before launch. During the flight, control commands are given in real time to control the aircraft to reach the target position within the desired flight time. Upon reaching the target, the acceleration of the aircraft converges.

2. The terminal time-constrained guidance method considering terminal acceleration convergence according to claim 1, characterized in that, The control command Obtained through the following formula (i): (one) in, This indicates a control command based on a proportional guidance law. Represents navigation constants; Indicates the speed of the aircraft; Indicates navigation gain; Indicates time-of-flight error; Indicates the distance between the aircraft and the target; Indicates the leading angle; A unit vector representing control commands based on proportional guidance laws; This represents the ratio between the component of the bias guidance command perpendicular to the intercept plane and its component in the in-plane direction. This represents a unit vector perpendicular to the intercept plane.

3. The terminal time-constrained guidance method considering terminal acceleration convergence according to claim 2, characterized in that, The control command based on the proportional guidance law We obtain it through the following formula (II): (two) in, Indicates the angular velocity of line of sight rotation; This indicates the direction of the aircraft's velocity vector.

4. The terminal time-constrained guidance method considering terminal acceleration convergence according to claim 3, characterized in that, The line of sight rotation angular velocity We obtain it through the following formula (iii): (three) in, A unit vector representing the direction of the aircraft's line of sight.

5. The terminal time-constrained guidance method considering terminal acceleration convergence according to claim 2, characterized in that, The time-of-flight error We obtain it through the following formula (iv): (Four) in, Indicates the expected flight time; Indicates the remaining flight time; Indicates the current time.

6. The terminal time-constrained guidance method considering terminal acceleration convergence according to claim 5, characterized in that, The remaining flight time We obtain it through the following formula (5): (five).

7. The terminal time-constrained guidance method considering terminal acceleration convergence according to claim 2, characterized in that, The forward angle Obtained through the following formula (VI): (six).

8. The terminal time-constrained guidance method considering terminal acceleration convergence according to claim 2, characterized in that, The unit vector of the control command based on the proportional guidance law We obtain it through the following formula (VII): (seven).

9. The terminal time-constrained guidance method considering terminal acceleration convergence according to claim 2, characterized in that, The unit vector perpendicular to the interception plane Obtained through the following formula (8): (eight).

10. The terminal time-constrained guidance method considering terminal acceleration convergence according to claim 2, characterized in that, The ratio between the component of the bias guidance command perpendicular to the intercept plane and its component in the in-plane direction. Obtained under the following conditions: When the desired terminal angle is within the intercept plane, The value is 0. When the desired terminal angle is not within the interception plane, The value is 1.

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