A method for precise speed control of an axisymmetric aircraft using additional control surface drag

Abstract

This invention discloses a method for precise speed control of an axisymmetric aircraft using additional control surface drag. The method includes: obtaining the nominal trajectory and aerodynamic data of the aircraft based on mathematical simulation results; using the nominal trajectory and aerodynamic data to obtain a nominal speed interpolation table and a speed control threshold interpolation table, thereby determining the nominal speed, speed control threshold, and speed control gain; acquiring real-time flight data of the aircraft; calculating a preliminary deceleration path control deflection angle command based on the deviation between the actual speed and the nominal speed and speed control threshold, combined with the speed control gain; performing nonlinear processing on the preliminary deceleration path control deflection angle command and superimposing it onto a single-chip control deflection angle command calculated by the aircraft's guidance law, and then sending it to the aircraft's servo mechanism to perform aerodynamic control of the control surfaces. This invention achieves precise control of the aircraft's landing speed without affecting the guidance law effect.

Description

Technical Field

[0001] This invention relates to the field of aircraft guidance and control, specifically to a method for precise speed control of an axisymmetric aircraft using additional control surface drag, applicable to situations where precise control of the aircraft's descent speed is required. Background Technology

[0002] Axisymmetric aircraft need to maintain both position and landing speed accuracy at the end of their trajectory. This is typically achieved through maneuvering to decelerate and control speed. However, this inevitably leads to a conflict between maneuvering deceleration and the guidance law at the end of the trajectory, causing a sharp drop in position accuracy. In such cases, the maneuvering deceleration function is often removed at the end of the trajectory to maintain position accuracy, resulting in poor landing speed control accuracy. Furthermore, maneuvering deceleration methods generally have poor speed control accuracy. How to achieve precise landing speed control without compromising guidance accuracy has been a long-standing search for a solution. Summary of the Invention

[0003] The purpose of this invention is to provide a method for precise speed control of an axisymmetric aircraft through additional control surface drag, so as to achieve precise control of the aircraft's descent speed without affecting the guidance law effect (i.e., terminal position accuracy).

[0004] To achieve the above objectives, the present invention employs the following technical solution: A method for precise speed control of an axisymmetric aircraft using additional control surface drag includes: The nominal trajectory and aerodynamic data of the aircraft are obtained based on the mathematical simulation results of the aircraft; the nominal velocity interpolation table and the velocity control threshold interpolation table are obtained using the nominal trajectory and aerodynamic data, thereby determining the nominal velocity, velocity control threshold and velocity control gain; Acquire real-time flight data of the aircraft, and calculate the initial deceleration channel rudder deflection command based on the deviation between the actual speed and the nominal speed and the speed control threshold, combined with the speed control gain. After the initial deceleration channel rudder deflection angle command is nonlinearly processed and superimposed onto the single-chip rudder deflection angle command calculated by the aircraft's guidance law, it is sent to the aircraft's servo mechanism to perform aerodynamic control on the rudder surface.

[0005] Furthermore, the distance between the aircraft and the target in the nominal trajectory is extracted. Aircraft speed Two variable vectors are used as a nominal velocity interpolation table; when the distance between the aircraft and the target is... At that time, the nominal speed is obtained by linear interpolation as follows: ;in This represents a linear interpolation function.

[0006] Furthermore, by mathematically simulating the process from different distances between the aircraft and the target in the deceleration channel until they meet, half the difference between the maximum deceleration channel rudder deflection angle and the undecelerated landing speed is used as the speed control threshold. The distance vector between the aircraft and the target at the start of deceleration is recorded. and speed control threshold vector As a speed control threshold interpolation table, the distance between the aircraft and the target can be obtained through linear interpolation. Speed ​​control threshold at time .

[0007] Furthermore, speed control gain The design is carried out by linearizing the deceleration channel of the aircraft and building a linearized model.

[0008] Further, calculate the initial deceleration path rudder deflection command according to the following formula. :

[0009] in For the mass of the aircraft, For dynamic pressure, The aerodynamic characteristic area of ​​the aircraft. This is the derivative of the aircraft drag coefficient with respect to the deceleration path rudder deflection angle. This refers to the real-time speed of the aircraft.

[0010] Furthermore, the process of nonlinearly processing the initial deceleration channel rudder deflection angle command is as follows:

[0011] in, The maximum absolute value of each individual rudder deflection angle command. These are the individual deflection angle commands for the four control surfaces calculated by the aircraft's guidance law. , , As an intermediate variable, For time k , This is the deceleration channel rudder deflection angle command at time k after nonlinear processing.

[0012] Furthermore, this is superimposed on the single-plate rudder deflection command calculated by the aircraft's guidance law, specifically:

[0013] in, The superimposed command corresponds to the deflection angle of a single control surface on the four control surfaces of the aircraft and is executed by the servo mechanism.

[0014] A terminal device includes a processor, a memory, and a computer program stored in the memory; when the processor executes the computer program, it implements a method for precise speed control of the axisymmetric aircraft by means of additional control surface drag.

[0015] A computer-readable storage medium storing a computer program; when executed by a processor, the computer program implements a method for precise speed control of the axisymmetric aircraft by means of additional control surface drag.

[0016] Compared with the prior art, the present invention has the following technical features: 1. This invention proposes the idea of ​​generating additional drag to reduce speed by adding additional rudder deflection angle. The added additional single-piece rudder deflection angle will not generate pitch, yaw channel forces and moments, nor will it generate rolling moments, but will only increase the axial drag of the aircraft.

[0017] 2. This invention obtains the deceleration channel rudder deflection command by comparing the deviations of real-time speed, nominal speed, and speed control threshold through proportional control and nonlinear processing. This allows for precise control of the aircraft's landing speed without affecting the effectiveness of the guidance law, meaning that precise landing speed control is achieved in the terminal phase while the accuracy of the landing point remains unaffected. Attached Figure Description

[0018] Figure 1 This is a flowchart illustrating the method of the present invention; Figure 2 This is a block diagram of the linear model for speed control parameter tuning; Figure 3 It is the definition of the positive deflection angle of a single-chip rudder command calculated by the guidance law; Figure 4 This is the definition of the positive deflection angle of the deceleration channel rudder deflection command; Figure 5 It is the rudder deflection command curve for the deceleration channel; Figure 6 These are the speed curves of aircraft using this method and those not using this method. Detailed Implementation

[0019] This invention proposes a method for precise speed control of an axisymmetric aircraft using additional control surface drag, wherein the axisymmetric aircraft has multiple axisymmetrically distributed control surfaces; the specific implementation process of this invention is described in conjunction with the accompanying drawings: Step 1: Obtain the nominal trajectory and aerodynamic data of the aircraft based on the mathematical simulation results of the aircraft; use the nominal trajectory and aerodynamic data to obtain the nominal speed interpolation table and the speed control threshold interpolation table, thereby determining the nominal speed, speed control threshold and speed control gain.

[0020] (1) Nominal speed.

[0021] Extract the distance between the aircraft and the target in the nominal trajectory. Aircraft speed Two variable vectors are used as a nominal velocity interpolation table; when the distance between the aircraft and the target is... At this point, the nominal speed can be obtained by linear interpolation. :

[0022] in This represents a linear interpolation function (with the same name as the one-dimensional linear interpolation function built into Matlab); the nominal trajectory of the aircraft is the ideal trajectory of the aircraft obtained through pre-simulation, which includes information such as the direction, speed, and distance between the aircraft and the target at each position.

[0023] (2) Speed ​​control threshold.

[0024] Based on aerodynamic data analysis of the aircraft's deceleration capability, a speed control threshold interpolation table is obtained. This invention introduces a deceleration channel into the existing pitch, yaw, and roll channels. Through mathematical simulation, the deceleration channel is used to simulate the process from different distances between the aircraft and the target until they meet. The maximum deceleration channel rudder deflection angle is preset, and half the difference between this angle and the undecelerated landing speed is used as the speed control threshold. The distance vector between the aircraft and the target at the start of deceleration is recorded. and speed control threshold vector As a speed control threshold interpolation table, the distance between the aircraft and the target can be obtained through linear interpolation. Speed ​​control threshold at time :

[0025] (3) Speed ​​control gain.

[0026] Speed ​​control gain The design can be carried out by linearizing the deceleration channel of the aircraft and building a linear model. The block diagram of the linear model for speed control parameter tuning is as follows. Figure 2 As shown, the value is generally approximately equal to 1; in the figure a ( s () is an acceleration command. This is the rudder deflection command. s For the Laplace operator.

[0027] Step 2: Obtain the aircraft's real-time flight data and determine its speed. With nominal speed and speed control threshold The deviation, combined with the speed control gain Calculate the initial deceleration path rudder deflection command .

[0028] Calculate the initial deceleration path rudder deflection command using the formula below. :

[0029] in For the mass of the aircraft, For dynamic pressure, The aerodynamic characteristic area of ​​the aircraft. This is the derivative of the aircraft drag coefficient with respect to the deceleration path rudder deflection angle. This refers to the real-time speed of the aircraft.

[0030] Step 3: Issue the initial deceleration channel rudder deflection command. The nonlinear processing is applied and superimposed onto the single-blade deflection angle command calculated by the aircraft's guidance law, and then sent to the aircraft's servo mechanism to perform aerodynamic control on the control surface in order to achieve precise control of the landing speed; wherein, the aircraft has four control surfaces distributed symmetrically.

[0031] (1) Nonlinear processing.

[0032]

[0033] in, The maximum absolute value of each individual rudder deflection angle command. These are the individual deflection angle commands for the four control surfaces calculated by the aircraft's guidance law. To perform the maximum value operation, , , As an intermediate variable, For time k , This is the deceleration channel rudder deflection angle command at time k after nonlinear processing.

[0034] (2) Superimposed on the single-blade deflection angle command calculated by the guidance law.

[0035] The positive deflection angle of the single-chip rudder command calculated by the guidance law is defined as follows: Figure 3 As shown, the positive deflection angle of the deceleration channel rudder deflection angle command is defined as follows: Figure 4 As shown; in this scheme, the aircraft coordinate system takes the aircraft axis as the X direction, corresponding to the roll channel; the Y and Z directions are set in a plane perpendicular to the missile axis, corresponding to the yaw channel and roll channel respectively; then, in the plane perpendicular to the missile axis, the positive deflection angle of the single-blade deflection command calculated by the guidance law (i.e., when the deflection angle command is positive) of the four control surfaces is counterclockwise; in the positive deflection angle of the deceleration channel deflection command, the control surfaces in the first and third quadrants are clockwise, and the control surfaces in the second and fourth quadrants are counterclockwise.

[0036] Therefore, the superposition formula is as follows:

[0037] in, The superimposed command corresponds to the deflection angle of a single control surface on the four control surfaces of the aircraft and is executed by the servo mechanism.

[0038] Example: Assuming an axisymmetric aircraft has an initial velocity of 775 m / s, its descent velocity without velocity control is 527.65 m / s. The required descent velocity is 500 m / s. What is the nominal trajectory distance between the aircraft and the target? m, nominal velocity of the orbital vehicle m / s, velocity control distance vector between the aircraft and the target m, speed control threshold vector m / s. Maximum absolute value of a single-chip rudder command. °, take The command to draw the deceleration channel rudder deflection angle is as follows: Figure 5 As shown, the velocity curves of the aircraft using this method and those not using this method are plotted as follows. Figure 6 As shown, it can be seen that by using a deflection angle of approximately 6 to 7 degrees, the speed control deceleration is 27.6 m / s with high accuracy.

[0039] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for precise speed control of an axisymmetric aircraft using additional control surface drag, characterized in that, include: The nominal trajectory and aerodynamic data of the aircraft are obtained based on the mathematical simulation results of the aircraft. Using nominal trajectory and aerodynamic data, a nominal speed interpolation table and a speed control threshold interpolation table are obtained, thereby determining the nominal speed, speed control threshold, and speed control gain; Acquire real-time flight data of the aircraft, and calculate preliminary deceleration channel rudder deflection commands based on the deviation between the actual speed and the nominal speed and speed control threshold, combined with the speed control gain, including: Extract the distance between the aircraft and the target in the nominal trajectory. Aircraft speed Two variable vectors are used as a nominal velocity interpolation table; when the distance between the aircraft and the target is... At that time, the nominal speed is obtained by linear interpolation as follows: ;in Represents a linear interpolation function; The process of the aircraft decelerating from different distances to the target in the deceleration channel is simulated mathematically. Half of the difference between the maximum deceleration channel rudder deflection angle and the undecelerated landing speed is used as the speed control threshold. The distance vector between the aircraft and the target at the start of deceleration is recorded. and speed control threshold vector As a speed control threshold interpolation table, the distance between the aircraft and the target can be obtained through linear interpolation. Speed ​​control threshold at time ; Calculate the initial deceleration path rudder deflection command using the formula below. : in For the mass of the aircraft, For dynamic pressure, The aerodynamic characteristic area of ​​the aircraft. This is the derivative of the aircraft drag coefficient with respect to the deceleration path rudder deflection angle. For the real-time speed of the aircraft, Speed ​​control gain; After the initial deceleration channel rudder deflection angle command is nonlinearly processed and superimposed onto the single-chip rudder deflection angle command calculated by the aircraft's guidance law, it is sent to the aircraft's servo mechanism to perform aerodynamic control on the rudder surface.

2. The method for precise speed control of an axisymmetric aircraft using additional control surface drag according to claim 1, characterized in that, Speed ​​control gain The design is carried out by linearizing the deceleration channel of the aircraft and building a linearized model.

3. The method for precise speed control of an axisymmetric aircraft using additional control surface drag according to claim 1, characterized in that, The process of nonlinearly processing the initial deceleration channel rudder deflection angle command is as follows: in, The maximum absolute value of each individual rudder deflection angle command. These are the individual deflection angle commands for the four control surfaces calculated by the aircraft's guidance law. , , As an intermediate variable, For time k , This is the deceleration channel rudder deflection angle command at time k after nonlinear processing.

4. The method for precise speed control of an axisymmetric aircraft using additional control surface drag according to claim 3, characterized in that, The single-plate rudder deflection command superimposed on the aircraft's guidance law calculation is as follows: in, The superimposed command corresponds to the deflection angle of a single control surface on the four control surfaces of the aircraft and is executed by the servo mechanism.

5. A terminal device, comprising a processor, a memory, and a computer program stored in the memory; characterized in that, When the processor executes the computer program, it implements the method for precise speed control of an axisymmetric aircraft by additional control surface drag according to any one of claims 1-4.

6. A computer-readable storage medium storing a computer program; characterized in that, When the computer program is executed by the processor, it implements the method for precise speed control of an axisymmetric aircraft by additional control surface drag according to any one of claims 1-4.

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