Statically unstable projectile-based acceleration feedback autopilot design method

Abstract

The invention discloses an acceleration feedback autopilot design method based on a statically unstable projectile. The method comprises the following steps: establishing a longitudinal linear kinetic equation; constructing an acceleration autopilot framework; acceleration autopilot control parameters are set, and an autopilot is obtained; an autopilot is adopted to control the flight state of the aircraft, an acceleration autopilot frame is of a three-ring autopilot structure and comprises a damping stabilizing inner ring, a stability enhancing loop and an acceleration loop outer ring, and feedback signals of the damping stabilizing inner ring are generated based on the pitch angle speed; a feedback signal of the stability enhancement loop is generated based on the longitudinal acceleration, and a feedback signal of the outer loop of the acceleration loop is generated based on the longitudinal acceleration. According to the method disclosed by the invention, the stability and controllability of the statically unstable aircraft can be realized, and the overload capacity of the statically unstable aircraft is remarkably improved.

Description

TECHNICAL FIELD

[0001] The application relates to a design method of an acceleration feedback autopilot based on a static unstable missile, and belongs to the technical field of aircraft control. BACKGROUND

[0002] The core task of the autopilot is to ensure that an aircraft accurately and robustly tracks an instruction signal generated by a guidance system, so that the aircraft can generate corresponding control force and torque according to the instruction signal, thereby enabling the aircraft to stably fly until hitting a target.

[0003] Most existing autopilots adopt a classic three-loop autopilot, which is good for traditional aircraft control, however, for a static unstable aircraft, when the aircraft deviates from the equilibrium state due to external disturbance, the aerodynamic moment generated by the missile at the moment when the disturbance disappears makes the aircraft deviate from the original equilibrium position, and the control effect of the classic three-loop autopilot is obviously poor.

[0004] Therefore, it is necessary to further study the existing autopilot to solve the problem of poor control of the static unstable aircraft. SUMMARY

[0005] In order to overcome the above problems, the present application has been researched in depth, and a design method of an acceleration feedback autopilot based on a static unstable missile is provided, which comprises the following steps:

[0006] S1, establishing a longitudinal linear dynamics equation;

[0007] S2, constructing an acceleration autopilot framework;

[0008] S3, setting acceleration autopilot control parameters to obtain an autopilot;

[0009] S4, using the autopilot to control the flight state of the aircraft.

[0010] In one preferred embodiment, in S1, the longitudinal linear dynamics equation is expressed as:

[0011]

[0012] Wherein, alpha represents an attack angle, b α represents a pitching force generated by the attack angle, b δ represents a pitching force caused by the elevator, delta e represents a rudder deflection angle, represents a pitch angle, a α represents a pitching moment caused by the attack angle, a ω represents a pitching damping moment caused by the pitch angle velocity, a δrepresents the pitching moment caused by the elevator, θ represents the trajectory inclination angle, V represents the flight speed, c represents the distance between the accelerometer installation position and the center of mass, and a y Indicates the longitudinal acceleration.

[0013] In a preferred embodiment, in S2, the acceleration autopilot framework includes a pitch loop autopilot and a yaw loop autopilot;

[0014] The yaw loop autopilot structure and the pitch loop autopilot structure are arranged symmetrically.

[0015] In a preferred embodiment, the pitch loop autopilot is a three-loop autopilot structure, comprising a damping stabilization inner loop, a stability enhancement loop, and an acceleration loop outer loop, wherein the feedback signal of the damping stabilization inner loop is based on the pitch angular velocity The feedback signal of the stability enhancement loop is generated based on the longitudinal acceleration a y Generate, the feedback signal of the outer loop of the acceleration loop is based on the longitudinal acceleration a y generate.

[0016] In a preferred embodiment, an acceleration gain K is set in the outer loop of the acceleration circuit. ac , for the longitudinal acceleration a y The signal after gain is used as the feedback signal of the outer loop of the acceleration circuit.

[0017] In a preferred embodiment, a stability gain K is set in the stability enhancement loop. I , for the longitudinal acceleration a y Gain is performed, and the gained signal is used as the feedback signal of the stability enhancement loop

[0018] In a preferred embodiment, an angular velocity gain K is set in the damping stabilization inner loop. G +cK ac K A , for the pitch angular velocity The signal after gain is used as the feedback signal of the damping stabilization inner loop.

[0019] In a preferred embodiment, a closed loop gain K is set in the pitch loop autopilot. DC , used to input acceleration instruction a yc Perform gain, and obtain the acceleration command a′ after gain yc It is superimposed with the feedback signal of the outer loop of the acceleration loop and then passes through the proportional module K A , integration module Then, it is superimposed with the feedback signal of the stability enhancement loop and the feedback signal of the damping stabilization inner loop, and the rudder deflection angle δ is generated after the servo gain.e , based on the rudder deflection angle δ e The longitudinal acceleration a is obtained by solving the longitudinal linear dynamic equation y .

[0020] In a preferred embodiment, in S3, the acceleration autopilot control parameters are set to:

[0021]

[0022]

[0023]

[0024] Among them, k1, k2, and k3 are intermediate variables, which are set as:

[0025]

[0026] The beneficial effects of the present invention include:

[0027] (1) Improving the overload capacity of the aircraft: By properly selecting the parameters of the damping circuit, the statically unstable aircraft can be stabilized and controlled, significantly improving the overload capacity of the statically unstable aircraft;

[0028] (2) Achieve rapid response: Through acceleration feedback, the autopilot can quickly perceive the dynamic changes of the aircraft and make corresponding adjustments and controls in a timely manner, enabling the aircraft to achieve rapid response and precise strikes in a short period of time;

[0029] (3) Simplified control system design: Traditional statically unstable aircraft usually require complex control systems and algorithms to maintain stability and precise strikes, while the acceleration feedback autopilot provided by the present invention can simplify the control system design and reduce manufacturing and maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A schematic flow chart of a method for designing an acceleration feedback autopilot based on statically unstable springs according to a preferred embodiment of the present invention is shown;

[0031] Figure 2 A schematic diagram of the acceleration autopilot framework structure in a statically unstable spring-based acceleration feedback autopilot design method according to a preferred embodiment of the present invention is shown;

[0032] Figure 3 The output response curve simulation diagram in Example 1 is shown. DETAILED DESCRIPTION

[0033] The present invention will be described in further detail below with reference to the accompanying drawings and examples, through which the features and advantages of the present invention will become more clearly understood.

[0034] The word "exemplary" is used exclusively herein to mean "serving as an example, example, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. Although various aspects of the embodiments are shown in the drawings, the drawings are not necessarily drawn to scale unless otherwise indicated.

[0035] According to the present invention, a statically unstable elastic acceleration feedback autopilot design method is provided. Figure 1 As shown, the following steps are included:

[0036] S1. Establish the longitudinal linear dynamic equation;

[0037] S2, build acceleration autopilot framework;

[0038] S3, setting acceleration autopilot control parameters and obtaining the autopilot;

[0039] S4. Use the autopilot to control the flight status of the aircraft.

[0040] In S1, the longitudinal linear dynamic equation is expressed as:

[0041]

[0042] Where α represents the angle of attack, b α represents the pitching force generated by the angle of attack, b δ represents the pitching force caused by the elevator, δ e Indicates the rudder angle, represents the pitch angle, a α represents the pitching moment caused by the angle of attack, a ω represents the pitch damping moment caused by the pitch angular velocity, a δ represents the pitching moment caused by the elevator, θ represents the trajectory inclination angle, V represents the flight speed, c represents the distance between the accelerometer installation position and the center of mass, and a y represents the longitudinal acceleration. ω z As state variables x, a y ,∫a y ,ω z As the output y, the state equation of the longitudinal linear dynamic equation is expressed as

[0043]

[0044] y=Cx+Du

[0045]

[0046]

[0047] wherein, represents the pitch angle.

[0048] In S2, the acceleration autopilot framework comprises a pitch loop autopilot and a yaw loop autopilot;

[0049] The yaw loop autopilot structure is symmetrically arranged with the pitch loop autopilot structure.

[0050] In the conventional autopilot, the feedback signals are generally the pitch angle, the pitch angular velocity and the longitudinal acceleration, and for a statically unstable aircraft, when the aircraft deviates from the equilibrium state due to external disturbance, the conventional autopilot will make the aircraft deviate from the original equilibrium position more at the moment when the disturbance disappears.

[0051] In the present application, the pitch loop autopilot is a three-loop autopilot structure, comprising a damping stability inner loop, a stability enhancement loop and an acceleration loop outer loop, as shown in Figure 2 wherein the feedback signal of the damping stability inner loop is generated based on the pitch angular velocity The feedback signal of the stability enhancement loop is generated based on the longitudinal acceleration a y The feedback signal of the acceleration loop outer loop is generated based on the longitudinal acceleration a y .

[0052] Preferably, an acceleration gain K ac is arranged in the acceleration loop outer loop, and the longitudinal acceleration a y is gain-controlled, and the gain-controlled signal is taken as the feedback signal of the acceleration loop outer loop.

[0053] A stability gain K I is arranged in the stability enhancement loop, and the longitudinal acceleration a y is gain-controlled, and the gain-controlled signal is taken as the feedback signal of the stability enhancement loop.

[0054] An angular velocity gain K G +cK ac K A is arranged in the damping stability inner loop, and the pitch angular velocity is gain-controlled, and the gain-controlled signal is taken as the feedback signal of the damping stability inner loop,

[0055] wherein the pitch angular velocity is solved by using the longitudinal linear dynamics equation based on the longitudinal acceleration a y .

[0056] Furthermore, a closed loop gain K is set in the pitch loop autopilot. DC , used to input acceleration instruction a yc Perform gain, and obtain the acceleration command a′ after gain yc It is superimposed with the feedback signal of the outer loop of the acceleration loop and then passes through the proportional module K A , integration module Then, it is superimposed with the feedback signal of the stability enhancement loop and the feedback signal of the damping stabilization inner loop, and the servo gain K is used to ACT Post-generated rudder deflection angle δ e , based on the rudder deflection angle δ e The longitudinal acceleration a is obtained by solving the longitudinal linear dynamic equation y .

[0057] The acceleration autopilot framework provided by the present invention can greatly improve the system stability of statically unstable aircraft compared to traditional autopilots. Furthermore, compared to other autopilots, the stability enhancement loop of the present invention adopts the longitudinal acceleration a y As a feedback signal, it can enable the statically unstable aircraft to respond more quickly, allowing the aircraft to achieve rapid response and precise strikes in a short period of time.

[0058] Based on the longitudinal acceleration a y The pitch angular velocity is obtained by solving the longitudinal linear dynamic equation Based on the rudder deflection angle δ e The longitudinal acceleration a is obtained by solving the longitudinal linear dynamic equation y The specific solution process is not described in detail in the present invention, and those skilled in the art can perform it based on experience.

[0059] Furthermore, the acceleration gain K ac , closed-loop gain K DC , proportional module K A , integration module Servo gain K ACT These are all commonly used gains or modules for autopilots. The present invention does not limit the specific settings of their parameters, and those skilled in the art can freely set them.

[0060] Preferably, the servo gain K ACT Set to a constant term.

[0061] In S3, when setting the acceleration autopilot control parameters, the dynamics of the accelerometer and angular rate gyroscope hardware are not considered. The feedback is placed at the servo, resulting in:

[0062]

[0063] Combined with the state equation of the longitudinal dynamic equation, the state feedback matrix can be obtained as:

[0064]

[0065] Among them, k1, k2, and k3 are intermediate variables.

[0066] The output feedback matrix is:

[0067]

[0068]

[0069] From the relationship between the output feedback matrix and the state feedback matrix, we can get:

[0070]

[0071] According to the pole placement method, the acceleration autopilot control parameters can be obtained:

[0072]

[0073]

[0074]

[0075] It should be understood that the various forms of the processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this disclosure can be performed in parallel, sequentially, or in a different order, as long as the desired results of the technical solutions disclosed in this disclosure can be achieved. This is not a limitation herein.

[0076] Example

[0077] Example 1

[0078] Conduct simulation experiments and obtain the autopilot by the following method:

[0079] S1. Establish the longitudinal linear dynamic equation;

[0080] S2, build acceleration autopilot framework;

[0081] S3. Set acceleration autopilot control parameters and obtain the autopilot.

[0082] In S1, the longitudinal linear dynamic equation is expressed as:

[0083]

[0084] In S2, the acceleration autopilot framework includes a pitch loop autopilot and a yaw loop autopilot, wherein the pitch loop autopilot structure is as follows: Figure 2 As shown, the yaw loop autopilot structure and the pitch loop autopilot structure are symmetrically arranged.

[0085] In S3, the acceleration autopilot control parameters are set as:

[0086]

[0087]

[0088]

[0089]

[0090] During the simulation, a statically unstable missile is used as the simulation object. During the simulation, the missile selects characteristic points with disturbances. The specific characteristic points are: a α =-175, b α =1.67, V=359; During the simulation, set k ACT =-1, K is obtained by S3 calculation A =0.0142, K I =0.0055, K G =0.0907.

[0091] During the simulation, the input acceleration command is set to a square wave signal of 1m / s 2 ,3m / s 2 ,2m / s 2 , the autopilot frequencies are set to 5rad / s, 15rad / s and 33rad / s respectively, and the output response curves are obtained as follows Figure 3 shown.

[0092] As can be seen from the figure, after the statically unstable missile is input with a changing square wave signal, the longitudinal acceleration can reach the corresponding stable state; at the same time, the autopilot frequency has little effect on the stable state. When the autopilot frequency increases, the system response time decreases, that is, the response speed increases.

[0093] The present invention has been described above with reference to preferred embodiments, but these embodiments are merely exemplary and serve only as illustrations. On this basis, various replacements and improvements can be made to the present invention, all of which fall within the scope of protection of the present invention.

Claims

1. A design method for an acceleration feedback autopilot based on static instability, characterized in that: include: S1. Establish the longitudinal linear dynamic equation; S2, build acceleration autopilot framework; S3, setting acceleration autopilot control parameters and obtaining the autopilot; S4. Use the autopilot to control the flight status of the aircraft.

2. The design method of an acceleration feedback autopilot based on statically unstable springs according to claim 1, characterized in that: In S1, the longitudinal linear dynamic equation is expressed as: Where α represents the angle of attack, b α represents the pitching force generated by the angle of attack, b δ represents the pitching force caused by the elevator, δ e Indicates the rudder angle, represents the pitch angle, a α represents the pitching moment caused by the angle of attack, a ω represents the pitch damping moment caused by the pitch angular velocity, a δ represents the pitching moment caused by the elevator, θ represents the trajectory inclination angle, V represents the flight speed, c represents the distance between the accelerometer installation position and the center of mass, and a y Indicates the longitudinal acceleration.

3. The design method of an acceleration feedback autopilot based on statically unstable springs according to claim 1, characterized in that: In S2, the acceleration autopilot framework includes a pitch loop autopilot and a yaw loop autopilot; The yaw loop autopilot structure and the pitch loop autopilot structure are arranged symmetrically.

4. The method for designing an acceleration feedback autopilot based on statically unstable springs according to claim 3, characterized in that: The pitch loop autopilot is a three-loop autopilot structure, including a damping stabilization inner loop, a stability enhancement loop, and an acceleration loop outer loop, wherein the feedback signal of the damping stabilization inner loop is based on the pitch angular velocity The feedback signal of the stability enhancement loop is generated based on the longitudinal acceleration a y Generate, the feedback signal of the outer loop of the acceleration loop is based on the longitudinal acceleration a y generate.

5. The design method of an acceleration feedback autopilot based on statically unstable springs according to claim 4, characterized in that: The acceleration gain K is set in the outer loop of the acceleration circuit. ac , for the longitudinal acceleration a y The signal after gain is used as the feedback signal of the outer loop of the acceleration circuit.

6. The method for designing an acceleration feedback autopilot based on statically unstable springs according to claim 4, characterized in that: A stability gain K is set in the stability enhancement loop I , for the longitudinal acceleration a y The signal after gain is used as the feedback signal of the stability enhancement loop.

7. The design method of an acceleration feedback autopilot based on statically unstable springs according to claim 4, characterized in that: The angular velocity gain K is set in the damping stabilization inner loop G +cK ac K A , for the pitch angular velocity The signal after gain is used as the feedback signal of the damping stabilization inner loop.

8. The method for designing an acceleration feedback autopilot based on statically unstable springs according to claim 4, characterized in that: In the pitch loop autopilot, a closed loop gain K is set DC , used to input acceleration instruction a yc Perform gain, and obtain the acceleration command a′ after gain yc It is superimposed with the feedback signal of the outer loop of the acceleration loop and then passes through the proportional module K A , integration module Then, it is superimposed with the feedback signal of the stability enhancement loop and the feedback signal of the damping stabilization inner loop, and the rudder deflection angle δ is generated after the servo gain. e , based on the rudder deflection angle δ e The longitudinal acceleration a is obtained by solving the longitudinal linear dynamic equation y .

9. The method for designing an acceleration feedback autopilot based on statically unstable springs according to claim 4, characterized in that: In S3, the acceleration autopilot control parameters are set as: Among them, k1, k2, and k3 are intermediate variables, which are set as:

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