Trajectory shaping method for hypersonic vehicle under initial position deviation

Abstract

The present application belongs to the field of aircraft guidance and control technology, and specifically discloses a trajectory shape preserving method for an initial position deviation of a supersonic aircraft, which comprises the following steps: obtaining the variation range of the height H and the Mach number Ma of the aircraft during flight according to the reference trajectory information; designing an aircraft guidance control system according to the variation range of the height H and the Mach number Ma and the initial launch condition deviation range; calculating the required command of the aircraft by the aircraft guidance system; and stably tracking the command calculated by the aircraft guidance system by the aircraft control system to maintain the original trajectory shape. In the case of an initial position deviation, the present application can keep the shape of the flight trajectory of the aircraft unchanged, and the attack angle variation law is also the same as that of the reference trajectory, thereby maintaining the aerodynamic characteristics and engine working characteristics of the original trajectory. The present application solves the problem that the original trajectory climbing law and acceleration law are destroyed when the conventional guidance control system corrects the initial position deviation of the aircraft.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aircraft guidance and control, and particularly relates to a trajectory shape preserving method for an initial position deviation of a supersonic aircraft. BACKGROUND

[0002] The supersonic aircraft is of great significance to the development of weapon systems in China. In the climbing stage, the shape of the reference trajectory contains the designed aircraft climbing and acceleration law. The aircraft flying according to the shape of the reference trajectory can make the climbing and acceleration satisfy the designed law, more effectively utilize the fuel quantity, and improve the flight performance of the supersonic aircraft.

[0003] However, due to the influence of environmental conditions and other factors, the launch position of the aircraft is prone to deviation. The correction of the deviation by the conventional guidance control system will destroy the original trajectory shape. This not only destroys the original trajectory climbing law, but also causes the change of the attack angle. The change of the attack angle affects the engine intake of the supersonic aircraft, and then affects the engine thrust, thereby destroying the original trajectory acceleration law. The destruction of the original trajectory climbing law and acceleration law will not only cause the waste of energy, but also even lead to the energy shortage of the aircraft and then stall the aircraft in the extreme case. SUMMARY

[0004] The purpose of the application is to solve the problem of the destruction of the original trajectory climbing law and acceleration law caused by the conventional guidance control system when correcting the initial position deviation of the aircraft. The application provides a trajectory shape preserving method for the initial position deviation of a supersonic aircraft.

[0005] The technical scheme of the application is as follows: a trajectory shape preserving method for the initial position deviation of a supersonic aircraft, comprising the following steps:

[0006] S1. According to the reference trajectory information, the change range of the height H and the Mach number Ma of the aircraft in the flight process is obtained;

[0007] S2. According to the change range of the height H and the Mach number Ma and the initial launch condition deviation range, the aircraft guidance system and the aircraft control system are designed;

[0008] S3. The aircraft guidance system is used to calculate the required instructions of the aircraft;

[0009] S4. The aircraft control system is used to stably track the instructions calculated by the aircraft guidance system, and keep the original trajectory shape.

[0010] The application has the following beneficial effects:

[0011] The designed trajectory shape keeping method can keep the shape of the flight trajectory of the vehicle unchanged, and the attack angle change rule is the same as that of the reference trajectory, so that the aerodynamic characteristics and engine working characteristics of the original trajectory are maintained.

[0012] As a preferred embodiment, the control system in step S2 realizes self-adaptation under the condition of initial position deviation by designing control parameters K I , K α and K ω .

[0013] The preferred embodiment has the following advantages:

[0014] By designing control parameters K I , K α and K ω in the control system, the control parameters change with the flight height and Mach number of the vehicle, so that good control effect can be achieved under different flight states.

[0015] As a preferred embodiment, the guidance system of the vehicle calculates the required command of the vehicle by trajectory inclination angle; the required command of the vehicle includes trajectory inclination angle command, height command and normal overload command.

[0016] The preferred embodiment has the following advantages:

[0017] The guidance system calculates the shape information of the reference trajectory into height command, trajectory inclination angle command and normal overload command, and the control system tracks these commands to realize trajectory shape keeping; and since these commands are calculated based on trajectory inclination angle, and the trajectory inclination angle is obtained by height interpolation, the flight trajectory can keep the original shape under the condition of initial position deviation.

[0018] As a preferred embodiment, the trajectory inclination angle command is obtained by height interpolation of the trajectory inclination angle by the guidance system of the vehicle.

[0019] As a preferred embodiment, the calculation formula of the trajectory inclination angle command is:

[0020]

[0021] Wherein, θ c represents the trajectory inclination angle command; θ(·) represents the function of the trajectory inclination angle obtained by height interpolation; H represents height interpolation; and [H1, H2] represents the range of height interpolation.

[0022] The preferred embodiment has the following advantages:

[0023] Since the trajectory inclination angle is obtained by height interpolation, the flight trajectory can keep the original shape under the condition of initial position deviation.

[0024] As a preference, the height command is obtained by integrating the ballistic angle command.

[0025] As a preference, the height command is obtained by integrating the ballistic angle command.

[0026]

[0027] wherein H c represents the height command; H0 represents the initial height when the vehicle accesses the guidance system; t0 represents the initial time when the vehicle accesses the guidance system; t represents the flight time; and V represents the flight speed of the vehicle.

[0028] The above-mentioned preferred scheme has the following beneficial effects:

[0029] Since the height command is obtained based on the ballistic angle command, and the ballistic angle is obtained by height interpolation, the flight trajectory can still maintain the original height shape under the condition of initial position deviation.

[0030] As a preference, the normal overload command is obtained by a reaching law of the ballistic angle command and the relationship between the ballistic angle change rate and the normal overload.

[0031] As a preference, the reaching law of the ballistic angle command has the following calculation formula:

[0032]

[0033] wherein represents the ballistic angle change rate; K θ represents the guidance parameter; and θ represents the ballistic angle.

[0034] As a preference, the normal overload command has the following calculation formula:

[0035] n yc = K θ V[θ(H)-θ] / g+cosθ

[0036] wherein n yc represents the normal overload command; V represents the flight speed of the vehicle; and g represents the acceleration of the earth's gravity.

[0037] The above-mentioned preferred scheme has the following beneficial effects:

[0038] Since the normal overload command is obtained based on the ballistic angle command, and the ballistic angle is obtained by height interpolation, the flight trajectory can still maintain the original shape under the condition of initial position deviation. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 Fig. 1 shows a flow chart of a ballistic shape preserving method under initial position deviation of a supersonic vehicle.

[0040] Figure 2 Shown is a schematic diagram of a trajectory conformal guidance control system for a supersonic aircraft under initial position deviation. DETAILED DESCRIPTION

[0041] The exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be understood that the embodiments shown and described in the accompanying drawings are merely exemplary and are intended to illustrate the principles and spirit of the present invention, rather than to limit the scope of the present invention.

[0042] like Figure 1 As shown, a trajectory conformal method for a supersonic vehicle under initial position deviation includes the following steps:

[0043] S1.According to the reference trajectory information, obtain the altitude H and Mach number M of the aircraft during flight a the range of change;

[0044] S2. According to the height H and Mach number M a Design the aircraft guidance system and control system based on the range of changes in the launch conditions and the deviation range of the initial launch conditions;

[0045] S3. Calculate the instructions required by the aircraft guidance system;

[0046] S4. Use the aircraft control system to stably track the instructions solved by the aircraft guidance system and maintain the original trajectory shape.

[0047] In this embodiment, the control system in step S2 is designed to control the parameter K I , K α and K ω Ensure that good control effects can be achieved in different flight conditions and realize the control system's self-adaptation under the initial position deviation conditions; the control parameter K I , K α and K ω is the control parameter of the three-loop overload autopilot, which is obtained by interpolation of the aircraft's flight altitude H and Mach number Ma.

[0048] In this embodiment, the aircraft guidance system calculates the instructions required by the aircraft through the ballistic inclination angle; the instructions required by the aircraft include ballistic inclination angle instructions, altitude instructions and normal overload instructions.

[0049] In this embodiment, the trajectory inclination angle instruction is obtained by interpolating the trajectory inclination angle according to the altitude by the aircraft guidance system.

[0050] In this embodiment, the calculation formula of the trajectory inclination angle instruction is:

[0051]

[0052] wherein θ c represents the ballistic pitch angle command; θ(·) represents the function of ballistic pitch angle according to the height interpolation; H represents the height interpolation; [H1, H2] represents the range of height interpolation, which is the reference ballistic height variation range. When there is deviation in the initial position, the initial height of the aircraft can not be in the range of height interpolation, in which case the closer boundary value of the range of height interpolation is taken.

[0053] In the embodiment, the height command is obtained by integrating the ballistic pitch angle command, and the transfer function from height to ballistic pitch angle is:

[0054]

[0055] wherein θ(s) represents the Laplace transform of the ballistic pitch angle; H(s) represents the Laplace transform of the height; V represents the flight speed of the aircraft; s is a variable in the complex frequency domain, and s on the right side of the equation represents an integral element.

[0056] In the embodiment, the calculation formula of the height command is:

[0057]

[0058] wherein H c represents the height command; H0 represents the initial height of the aircraft when the guidance system is accessed; t0 represents the initial time when the guidance system is accessed; t represents the flight time; V represents the flight speed of the aircraft.

[0059] In the embodiment, the normal overload command is obtained by the approaching law of the ballistic pitch angle command and the relationship between the ballistic pitch angle rate and the normal overload, and the transfer function from the ballistic pitch angle to the normal overload is:

[0060]

[0061] wherein θ(s) represents the Laplace transform of the ballistic pitch angle; ny(s) represents the Laplace transform of the normal overload.

[0062] In the embodiment, the calculation formula of the approaching law of the ballistic pitch angle command is:

[0063]

[0064] wherein represents the ballistic pitch angle rate; θ represents the ballistic pitch angle; K θIt indicates the guidance parameter, which affects the rate of tracking the ballistic inclination instruction. This parameter is adjusted with the change of altitude H and Mach number Ma, and the adjustment range is 0.1~0.4. When the flight pressure q is large, the aircraft has a stronger ability to change the ballistic inclination, so in this state K θ The value is larger. On the contrary, when the flight pressure q is small, K θ The value is smaller.

[0065] In this embodiment, the normal overload instruction calculation formula is:

[0066] n yc =K θ V[θ(H)-θ] / g+cosθ

[0067] Among them, n yc Indicates the normal overload command; V represents the flight speed of the aircraft; g represents the acceleration of gravity.

[0068] The specific working principle and process of the present invention are:

[0069] The present invention is designed as Figure 2 The guidance and control system shown can maintain ballistic shape information, wherein the guidance system calculates the altitude, ballistic inclination and overload instructions required by the aircraft based on the ballistic shape information carried by the ballistic inclination, and the control system stably tracks these instructions so that the actual flight trajectory of the aircraft can maintain the reference ballistic shape, and the guidance and control system needs to be able to adapt to different initial position deviation conditions and still maintain the original ballistic shape under different deviation conditions.

[0070] According to the trajectory conformal method of a supersonic aircraft under initial position deviation proposed by the present invention, the six degrees of freedom of the trajectory under different deviation conditions are simulated and verified.

[0071] The baseline trajectory has an initial altitude of 11 km. To verify trajectory conformality under various initial position deviations, points were selected at 0.1 km intervals within the range of 10.5 km to 11.5 km as initial conditions for the simulation, corresponding to eleven flight trajectories that account for initial position deviations. The simulation starts at the launch moment and ends after the vehicle reaches cruise mode. Considering the safety of the carrier aircraft and the stability of the missile during the initial launch, the conformal guidance system is deactivated for 30 seconds after launch. The control system tracks the normal overload command of the baseline trajectory, and after 30 seconds, the conformal guidance control system is engaged. Simulations have verified that this method can maintain the shape of the vehicle's flight trajectory, and the angle of attack changes in the same manner as the baseline trajectory.

[0072] Those skilled in the art will appreciate that the embodiments described herein are presented for purposes of illustration and that the inventive principles are not limited to these particular embodiments. Other variations and modifications can be made to the embodiments without departing from the spirit and scope of the inventive principles.

Claims

1. A method for trajectory conformality of a supersonic vehicle under initial position deviation, characterized by: S1.According to the reference trajectory information, obtain the altitude of the aircraft during flight and Mach number the range of change; S2. According to the height ,Mach number Design the aircraft guidance system and control system based on the range of changes in the launch conditions and the deviation range of the initial launch conditions; S3. The aircraft guidance system calculates the required instructions for the aircraft; the aircraft guidance system calculates the required instructions for the aircraft through the ballistic inclination angle; the instructions required for the aircraft include a ballistic inclination angle instruction, an altitude instruction, and a normal overload instruction; the ballistic inclination angle instruction is obtained by the aircraft guidance system by interpolating the ballistic inclination angle according to the altitude; the calculation formula for the ballistic inclination angle instruction is: in, Indicates the ballistic inclination angle command; A function representing the interpolation of ballistic inclination according to altitude; Indicates height interpolation; Indicates the range of height interpolation; The normal overload command is obtained by calculating the approaching law of the trajectory inclination command and the relationship between the trajectory inclination change rate and the normal overload. The formula for calculating the approaching law of the trajectory inclination command is: in, Indicates the rate of change of trajectory inclination; Indicates guidance parameters; Indicates the ballistic inclination angle; The calculation formula for normal overload instruction is: in, Indicates normal overload instruction; Indicates the flight speed of the aircraft; represents the acceleration due to gravity; S4. Use the aircraft control system to stably track the instructions solved by the aircraft guidance system and maintain the original trajectory shape.

2. The method for trajectory conformality under initial position deviation of a supersonic vehicle according to claim 1, characterized in that: The control system in step S2 is designed by controlling the parameters 、 and Realize self-adaptation under the conditions of initial position deviation.

3. The trajectory conformal method for a supersonic vehicle under initial position deviation according to claim 1, characterized in that: The altitude instruction is obtained by integrating the trajectory inclination instruction.

4. The trajectory conformal method for a supersonic vehicle under initial position deviation according to claim 3, characterized in that: The calculation formula of the height instruction is: in, Indicates altitude instruction; Indicates the initial altitude of the aircraft when it is connected to the guidance system; Indicates the initial time when the aircraft is connected to the guidance system; Indicates flight time; Indicates the aircraft's flight speed.

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