A reusable launch vehicle control method based on an elliptical disturbance observer

Abstract

The application provides a reuse carrier control method based on an elliptical interference observer, which measures the vertical acceleration, the pitch angle and the pitch angular velocity of the carrier through an accelerometer and a goniometer gyro; then the pitch angle expected instruction, the pitch angular velocity task expected instruction and the acceleration task expected instruction are adopted in a way of error layer-by-layer cascade superposition to realize the compatible and unified control of the three instructions of angle, angular velocity and acceleration, and the instruction switching is very convenient; meanwhile, the solving of the pitch angular acceleration estimation signal and the formation of the acceleration sliding mode surface are realized through anti-saturation exponential transformation, inverse proportional transformation, linear and nonlinear mixed transformation and nonlinear mixed integral, and the final pitch channel control signal is formed by superimposing the sliding mode inverse proportional switching signal and the sliding mode mixed integral signal, so that the stable control of the carrier is realized.

Description

Technical Field

[0001] This invention relates to the field of stability and control of reusable launch vehicles, and more specifically, to a reusable launch vehicle control method based on an elliptic disturbance observer. Background Technology

[0002] A reusable launch vehicle is a multi-functional high-speed aircraft capable of repeatedly traversing high-altitude space, possessing reusability, and performing a series of tasks according to mission requirements. It can complete designated tasks in high altitudes, hover at near-high altitudes or pass through designated waypoints to perform information collection and transmission, satellite launches, and more. It combines the characteristics of aviation and aerospace, capable of performing high-altitude missions such as satellite launches and orbital servicing, and can return to Earth like a space shuttle. After simple maintenance and repair, it can continue to perform new space missions, significantly reducing operating costs. Reusable launch vehicles integrate the technologies of launch vehicles, space shuttles, and spacecraft, representing a trend in the development of aerospace technology worldwide, and possessing significant military and civilian value. However, reusable launch vehicles suffer from significant model uncertainties and external disturbances due to the highly variable space environment; conventional PID control technology struggles to achieve good adaptability in different environments. Based on the above background reasons, this invention proposes a method using an elliptical interference observer to adaptively estimate the pitch angle error and pitch angular velocity error after comprehensive error conversion, thereby realizing overall interference estimation feedback control. This enables the entire reusable launch vehicle to have good adaptability in high and low altitude environments, thus giving this invention great engineering practical value.

[0003] It should be noted that the information in the background section above is only used to enhance the understanding of the background of the present invention, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0004] The purpose of this invention is to provide a reusable launch vehicle control method based on an elliptical interference observer, thereby overcoming the problem of weak anti-interference capability caused by the limitations and defects of related technologies.

[0005] According to one aspect of the present invention, a reusable launch vehicle control method based on an elliptic disturbance observer is provided, comprising the following steps: Step S10: Install an angle-measuring gyroscope on the reusable launch vehicle to measure the pitch angle signal of the reusable launch vehicle. Then, set the desired pitch angle signal according to the flight mission and compare it to obtain the pitch angle error signal. Then, perform a nonlinear half-power integral operation on the pitch angle error signal to obtain the pitch angle error half-power integral signal. Install a velocity-measuring gyroscope on the reusable launch vehicle to measure the pitch angular velocity signal of the reusable launch vehicle. Then, superimpose the pitch angle error signal and the pitch angle error half-power integral signal to form a combined pitch angle error signal. Then, design a first-order differential filter to obtain the pitch angular velocity approximate differential signal through the pitch angular velocity signal. Then, construct the observer state differential signal based on the pitch angle error signal, the pitch angular velocity approximate differential signal, and the interference observation control signal.

[0006] Step S20: Integrate the differential signal of the observer state to obtain the observer state signal; then superimpose the pitch angle combined error signal to obtain the comprehensive observer state signal; then perform a limiting transformation on the comprehensive observer state signal to obtain the observation state limiting signal; then perform an elliptic transformation on the observation limiting signal to obtain the observation state elliptic transformation signal; then perform an inverse proportional transformation on the observation state elliptic transformation signal to obtain the observation state inverse proportional signal.

[0007] Step S30: Based on the observed state elliptic inverse ratio signal, the observer's comprehensive state signal, and the pitch angle error signal, the pitch error compensation rate signal is solved using adaptive and semi-power transformation and coincidence function switching; then, a nonlinear semi-power integration is performed to obtain the pitch error compensation signal; the observed state elliptic inverse ratio signal, the observer's comprehensive state signal, and the pitch angle velocity signal are solved using adaptive and semi-power transformation and coincidence function switching; then, a nonlinear semi-power integration is performed to obtain the pitch velocity compensation signal.

[0008] Step S40: The pitch error compensation signal, pitch speed compensation signal, observer integrated status signal, and observation status elliptic inverse ratio signal are superimposed to obtain the interference observation control signal; then, the pitch angle combined error signal is subjected to amplitude limiting transformation to obtain the pitch angle combined error amplitude limiting signal; then, the pitch angle combined error amplitude limiting signal is subjected to elliptic transformation to obtain the pitch angle elliptic transformation signal; then, the pitch angle elliptic transformation signal is subjected to inverse proportional transformation to obtain the pitch angle elliptic inverse ratio signal.

[0009] Step S50: The pitch angle combined error ellipse sign cross signal is obtained by performing sign transformation on the pitch angle combined error ellipse inverse ratio signal and the pitch angle combined error signal; then, the pitch angle combined error ellipse sign cross signal is obtained by combining the pitch angle combined error ellipse inverse ratio signal and the pitch angle combined error limiting signal; then, the pitch angle combined error integral signal is obtained by performing nonlinear half-power integration on the pitch angle combined error signal and the pitch angle combined error signal; finally, the interference observation control signal, the pitch angle combined error signal, the pitch angle combined error ellipse sign cross signal, and the pitch angle combined error ellipse limiting signal are superimposed to obtain the final pitch control signal of the repeating launch vehicle, thereby achieving stable tracking control of the desired pitch angle.

[0010] In one exemplary embodiment of the present invention, a nonlinear half-power integral operation is performed on the pitch angle error signal to obtain a pitch angle error half-power integral signal; a velocimetric gyroscope is installed on the reusable vehicle to measure the pitch angular velocity signal of the reusable vehicle; then the pitch angle error signal and the pitch angle error half-power integral signal are superimposed to form a combined pitch angle error signal; a first-order differential filter is then designed to obtain an approximate differential signal of the pitch angular velocity from the pitch angular velocity signal; then, based on the pitch angle error signal, the approximate differential signal of the pitch angular velocity, and the interference observation control signal, an observer state differential signal is constructed, including: ; ; ; ; ; in To reuse the launch vehicle's pitch angle signal, For the desired pitch angle signal, This is the pitch angle error signal; For constant time parameters of the integral, For constant parameters of the semi-power transformation, This is a constant integration threshold parameter; The pitch angle error is a half-power integral signal; This is the pitch angular velocity signal of the repetitive launch vehicle; , For constant combination parameters, This is the pitch angle combination error signal; These are the constant parameters of the first-order filter differentiator. The differential operator is the transfer function of the filter differentiator; This is the approximate differential signal of the pitch angular velocity; These are the constant parameters of the observer. To prevent interference with the observation and control signal, the initial value is set to 0. This is the differential signal of the observer state.

[0011] In one exemplary embodiment of the present invention, the observer state signal is obtained by integrating the differential observer state signal; then, the elevation angle combination error signal is superimposed to obtain the comprehensive observer state signal; then, the comprehensive observer state signal is subjected to a limiting transformation to obtain an observation state limiting signal; then, the observation limiting signal is subjected to an elliptic transformation to obtain an observation state elliptic transformation signal; and then, the observation state elliptic transformation signal is subjected to an inverse proportional transformation to obtain an observation state inverse elliptic proportional signal, including: ; ; ; ; ; in This is the observer's state signal; This is the overall state signal of the observer; , The limiting parameter is a constant value; Amplitude limiting signal for observation status; These are constant elliptic transformation parameters; The elliptic transformation signal for the observation state; It is a constant inverse proportional parameter. The signal is the inverse ratio of the observed ellipse.

[0012] In one exemplary embodiment of the present invention, based on the observed state elliptic inverse ratio signal, the observer's comprehensive state signal, and the pitch angle error signal, an adaptive and semi-power transform and a coincidence function switching method are used to solve for the pitch error compensation rate signal; then, a nonlinear semi-power integration is performed to obtain the pitch error compensation signal; the observed state elliptic inverse ratio signal, the observer's comprehensive state signal, and the pitch angle velocity signal are used to solve for the pitch velocity compensation rate signal using an adaptive and semi-power transform and a coincidence function switching method; then, a nonlinear semi-power integration is performed to obtain the pitch velocity compensation signal, including: ; ; ; ; in For symbolic functions, For constant parameters, This is the threshold parameter for the integral constant. This is a constant parameter used to adjust the convergence speed of the pitch error compensation signal; This is the pitch error compensation rate signal; This is the pitch error compensation signal; For constant parameters, This is a constant parameter used to adjust the convergence speed of the pitch speed compensation signal; This is the pitch speed compensation rate signal; This is the pitch speed compensation signal.

[0013] In one exemplary embodiment of the present invention, an interference observation control signal is obtained by superimposing the pitch error compensation signal, pitch speed compensation signal, observer integrated status signal, and observation status elliptic inverse ratio signal; then, a limiting transformation is performed on the pitch angle combined error signal to obtain a pitch angle combined error limiting signal; then, an elliptic transformation is performed on the pitch angle combined error limiting signal to obtain a pitch angle elliptic transformation signal; finally, an inverse proportional transformation is performed on the pitch angle elliptic transformation signal to obtain a pitch angle elliptic inverse ratio signal, including: ; ; ; ; Among them To interfere with the observation and control signals, , It is a constant parameter; This is a pitch angle combination error limiting signal; This is an elliptic transform signal for the pitch angle; This is the pitch angle elliptic inverse ratio signal.

[0014] In one exemplary embodiment of the present invention, a sign transformation is performed on the pitch angle elliptic inverse ratio signal and the pitch angle combined error signal to obtain a pitch angle combined error elliptic sign cross signal; then, the pitch angle elliptic inverse ratio signal and the pitch angle combined error limiting signal are combined to obtain a pitch angle elliptic limiting signal; then, a nonlinear half-power integration is performed on the pitch angle elliptic limiting signal and the pitch angle combined error signal to obtain a pitch angle combined error integral signal; finally, the interference observation control signal, the pitch angle combined error signal, the pitch angle combined error elliptic sign cross signal, and the pitch angle elliptic limiting signal are superimposed to obtain the final pitch control signal of the repeating launch vehicle, including: ; ; ; ; in The ellipse symbol crossover signal represents the pitch angle combination error. This is an elliptical amplitude-limited signal for pitch angle; For the constant threshold parameter of the integral, This is the integral signal of the pitch angle combination error; , , For constant control parameters, This is the final pitch control signal for the reusable launch vehicle.

[0015] Beneficial effects This invention discloses a reusable launch vehicle control method based on an elliptical disturbance observer. Its main innovations are as follows: First, it proposes a method for constructing an elliptical observer, enabling pitch channel disturbance estimation. Furthermore, it employs elliptical sign crossing and elliptical amplitude limiting signals in the final pitch channel control law, introducing feedback cancellation into the final control, thus giving the entire launch vehicle's attitude control strong disturbance adaptive capability. Second, it combines the observer with an adaptive method to adaptively estimate and compensate for pitch error and pitch speed, primarily addressing the issue of unknown information in the observer structure. Traditional observers require precise knowledge of the system structure, which is difficult for reusable launch vehicles. This invention, however, does not require precise system structure information in the use of the observer because the inaccurate parts are compensated for through adaptive estimation.

[0016] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit the invention. Attached Figure Description

[0017] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0018] Figure 1 This is a flowchart of a reusable launch vehicle control method based on an elliptic interference observer provided by the present invention; Figure 2 This is the pitch angle signal curve (unit: degrees) of the reusable carrier provided by the method in the embodiments of the present invention. Figure 3 This is the pitch angle error signal curve (unit: degrees) of the method provided in the embodiments of the present invention. Figure 4 This is the pitch angular velocity signal curve (unit: meters per second) of the reusable carrier provided by the embodiment of the present invention. Figure 5This is the pitch angular velocity approximate differential signal curve (unitless) of the method provided in the embodiments of the present invention. Figure 6 This is the pitch speed compensation signal curve (unitless) of the method provided in the embodiments of the present invention. Figure 7 This is the pitch angle combination error integral signal curve (unitless) of the method provided in the embodiment of the present invention. Figure 8 This is the final pitch control signal curve (unitless) of the reusable carrier provided by the method in the embodiments of the present invention. Detailed Implementation

[0019] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided to make the invention more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art. The described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a full understanding of embodiments of the invention. However, those skilled in the art will recognize that the technical solutions of the invention may be practiced with one or more of these specific details omitted, or other methods, components, apparatus, steps, etc., may be employed. In other instances, well-known technical solutions are not shown or described in detail to avoid obscuring various aspects of the invention.

[0020] This invention provides a reusable launch vehicle control method based on an elliptical interference observer. It measures the launch vehicle's pitch angle and pitch velocity using angle-measuring and velocity-measuring gyroscopes, respectively, and superimposes the pitch angle error half-power integral signal to form a combined pitch angle error signal. Then, it constructs an observer state differential signal based on the pitch velocity approximate differential signal and the interference observation control signal, and integrates it to obtain the observer's state. The interference observation control signal is obtained by performing an elliptic transformation on the observer's comprehensive state signal, thus constructing an interference estimation signal. An inverse elliptic proportional signal of the observation state is used to adaptively estimate the pitch error and velocity. Finally, the combined pitch angle error signal is subjected to an elliptic amplitude-limiting transformation, and the pitch velocity, error interference compensation signal, and interference observation control signal are superimposed to form the final pitch control signal for the reusable launch vehicle, achieving stable tracking control of the desired pitch angle.

[0021] The following will, with reference to the accompanying drawings, further explain and illustrate a reusable launch vehicle control method based on an elliptic interference observer according to the present invention. (Reference) Figure 1 As shown, this reusable launch vehicle control method based on an elliptic disturbance observer may include the following steps: Step S10: Install an angle-measuring gyroscope on the reusable launch vehicle to measure the pitch angle signal of the reusable launch vehicle. Then, set the desired pitch angle signal according to the flight mission and compare it to obtain the pitch angle error signal. Then, perform a nonlinear half-power integral operation on the pitch angle error signal to obtain the pitch angle error half-power integral signal. Install a velocity-measuring gyroscope on the reusable launch vehicle to measure the pitch angular velocity signal of the reusable launch vehicle. Then, superimpose the pitch angle error signal and the pitch angle error half-power integral signal to form a combined pitch angle error signal. Then, design a first-order differential filter to obtain the pitch angular velocity approximate differential signal through the pitch angular velocity signal. Then, construct the observer state differential signal based on the pitch angle error signal, the pitch angular velocity approximate differential signal, and the interference observation control signal.

[0022] Specifically, this can be broken down into the following five steps. The first step is to install an angle-measuring gyroscope on the reusable launch vehicle to measure its pitch angle signal. Then, based on the flight mission, a desired pitch angle signal is set, and the results are compared to obtain the pitch angle error signal, as follows: ; in To reuse the launch vehicle's pitch angle signal, For the desired pitch angle signal, This is the pitch angle error signal.

[0023] The second step involves performing a nonlinear half-power integral operation on the pitch angle error signal to obtain the pitch angle error half-power integral signal as follows: ; in For constant time parameters of the integral, For constant parameters of the semi-power transformation, This is a constant integration threshold parameter; The pitch angle error is a half-power integral signal.

[0024] The third step involves installing a velocimetric gyroscope on the reusable launch vehicle to measure its pitch angular velocity signal. Then, the pitch error signal and the pitch error half-power integral signal are superimposed to form the combined pitch error signal as follows: ; in This is the pitch angular velocity signal of the repetitive launch vehicle; , For constant combination parameters, This is the pitch angle combination error signal.

[0025] The fourth step is to design a first-order differential filter to obtain the approximate differential signal of the pitch angular velocity from the pitch angular velocity signal, as follows: ; in These are the constant parameters of the first-order filter differentiator. The differential operator is the transfer function of the filter differentiator; This is the approximate differential signal of the pitch angular velocity.

[0026] Fifth, based on the pitch angle error signal, the approximate differential signal of the pitch angular velocity, and the interference observation control signal, construct the observer state differential signal as follows: ; in These are the constant parameters of the observer. To prevent interference with the observation and control signal, the initial value is set to 0. This is the differential signal of the observer state.

[0027] Step S20: Integrate the differential signal of the observer state to obtain the observer state signal; then superimpose the pitch angle combined error signal to obtain the comprehensive observer state signal; then perform a limiting transformation on the comprehensive observer state signal to obtain the observation state limiting signal; then perform an elliptic transformation on the observation limiting signal to obtain the observation state elliptic transformation signal; then perform an inverse proportional transformation on the observation state elliptic transformation signal to obtain the observation state inverse proportional signal.

[0028] Specifically, it can be broken down into the following five steps. The first step is to integrate the differential signal of the observer state to obtain the observer state signal as follows: ; in This is the observer's state signal.

[0029] The second step involves superimposing the elevation angle combined error signals to obtain the observer's overall state signal, as follows: ; in This is the overall state signal of the observer.

[0030] The third step is to perform a limiting transformation based on the observer's overall state signal to obtain the observation state limiting signal as follows: ; in , The limiting parameter is a constant value; This is a limit signal for the observation state.

[0031] The fourth step is to perform an elliptic transformation based on the observed amplitude limiting signal, resulting in the following observed state elliptic transformation signal: ; in These are constant elliptic transformation parameters. The signal is the elliptic transformation signal for the observation state.

[0032] Fifth, perform an inverse proportional transformation on the observed state elliptic transformation signal to obtain the observed state elliptic inverse proportional signal as follows: ; in It is a constant inverse proportional parameter. The signal is the inverse ratio of the observed ellipse.

[0033] Step S30: Based on the observed state elliptic inverse ratio signal, the observer's comprehensive state signal, and the pitch angle error signal, the pitch error compensation rate signal is solved using adaptive and semi-power transformation and coincidence function switching; then, a nonlinear semi-power integration is performed to obtain the pitch error compensation signal; based on the observed state elliptic inverse ratio signal, the observer's comprehensive state signal, and the pitch angle velocity signal, the pitch velocity compensation rate signal is solved using adaptive and semi-power transformation and coincidence function switching; then, a nonlinear semi-power integration is performed to obtain the pitch velocity compensation signal.

[0034] Specifically, this can be broken down into the following two steps. First, based on the observed state elliptic inverse ratio signal, the observer's overall state signal, and the pitch angle error signal, the pitch error compensation rate signal is solved using adaptive and semi-power transforms, along with coincidence function switching. Then, a nonlinear semi-power integral is performed to obtain the pitch error compensation signal as follows: ; ; in For symbolic functions, For constant parameters, This is the threshold parameter for the integral constant. This is a constant parameter used to adjust the convergence speed of the pitch error compensation signal; This is the pitch error compensation rate signal; This is the pitch error compensation signal; This is a constant parameter.

[0035] The second step involves using the observed state elliptic inverse ratio signal, the observer's overall state signal, and the pitch angular velocity signal, along with adaptive and semi-power transforms and coincidence function switching, to solve for the pitch velocity compensation rate signal. Then, a nonlinear semi-power integral is performed to obtain the pitch velocity compensation signal as follows: ; ; in This is a constant parameter used to adjust the convergence speed of the pitch speed compensation signal; This is the pitch speed compensation rate signal; This is the pitch speed compensation signal.

[0036] Step S40: The pitch error compensation signal, pitch speed compensation signal, observer integrated status signal, and observation status elliptic inverse ratio signal are superimposed to obtain the interference observation control signal; then, the pitch angle combined error signal is subjected to amplitude limiting transformation to obtain the pitch angle combined error amplitude limiting signal; then, the pitch angle combined error amplitude limiting signal is subjected to elliptic transformation to obtain the pitch angle elliptic transformation signal; finally, the pitch angle elliptic transformation signal is subjected to inverse proportional transformation to obtain the pitch angle elliptic inverse ratio signal.

[0037] Specifically, it can be broken down into the following four steps. The first step involves superimposing the pitch error compensation signal, pitch speed compensation signal, observer integrated status signal, and observation status ellipse inverse ratio signal to obtain the interference observation control signal as follows: ; in To interfere with the observation and control signals, , This is a constant parameter.

[0038] The second step involves performing a limiting transformation on the pitch angle combined error signal to obtain the pitch angle combined error limiting signal as follows: ; in This is a pitch angle combination error limiting signal.

[0039] The third step is to perform an elliptic transform on the pitch angle combined error limiting signal, resulting in the following pitch angle elliptic transform signal: ; in This is the pitch angle elliptic transformation signal.

[0040] The fourth step is to perform an inverse proportional transformation on the pitch angle elliptic transform signal to obtain the pitch angle elliptic inverse proportional signal as follows: ; Among them This is the pitch angle elliptic inverse ratio signal.

[0041] Step S50: The pitch angle combined error ellipse sign cross signal is obtained by performing sign transformation on the pitch angle combined error ellipse inverse ratio signal and the pitch angle combined error signal; then, the pitch angle combined error ellipse sign cross signal is obtained by combining the pitch angle combined error ellipse inverse ratio signal and the pitch angle combined error limiting signal; then, the pitch angle combined error integral signal is obtained by performing nonlinear half-power integration on the pitch angle combined error signal and the pitch angle combined error signal; finally, the interference observation control signal, the pitch angle combined error signal, the pitch angle combined error ellipse sign cross signal, and the pitch angle combined error ellipse limiting signal are superimposed to obtain the final pitch control signal of the repeating launch vehicle, thereby achieving stable tracking control of the desired pitch angle.

[0042] Specifically, it can be broken down into the following four steps. The first step is to perform a sign transformation on the pitch angle elliptic inverse ratio signal and the pitch angle combined error signal to obtain the pitch angle combined error elliptic sign crossover signal as follows: ; in The ellipse symbol cross signal represents the pitch angle combination error.

[0043] The second step involves combining the pitch angle elliptic inverse ratio signal with the pitch angle combined error limiting signal to obtain the pitch angle elliptic limiting signal as follows: ; in This is an elliptical amplitude-limited signal for pitch angle.

[0044] The third step involves performing a nonlinear half-power integral on the pitch angle elliptic limiting signal and the pitch angle combined error signal to obtain the integrated pitch angle combined error signal, as follows: ; in For constant threshold parameters of integration, This is the integral signal of the pitch angle combination error.

[0045] The fourth step involves superimposing the pitch angle combined error integral signal, the interference observation control signal, the pitch angle combined error signal, the pitch angle combined error ellipse sign crossover signal, and the pitch angle ellipse limiting signal to obtain the final pitch control signal for the repeatable launch vehicle, as follows: ; in , , For constant control parameters, This is the final pitch control signal for the reusable launch vehicle.

[0046] Case Implementation and Computer Simulation Results Analysis In step S10, select Spend, , , The pitch angle signal of the reusable launch vehicle is obtained as follows: Figure 2 As shown; the pitch angle error signal is obtained as follows. Figure 3 As shown; the pitch angular velocity signal of the repetitive launch vehicle is obtained as follows: Figure 4 As shown, the approximate differential signal of the pitch angular velocity is obtained as follows: Figure 5 As shown.

[0047] In step S20, select , , , .

[0048] In step S30, select , , , The pitch speed compensation signal is obtained as follows: Figure 6 As shown.

[0049] In step S40, select , .

[0050] In step S50, select The integral signal of the pitch angle combination error is obtained as follows: Figure 7 As shown, the final pitch control signal of the reusable launch vehicle is obtained as follows: Figure 8 As shown.

[0051] Depend on Figure 2 It can be seen that the attitude angle of the reusable launch vehicle can stably track the desired signal by 13 degrees; from Figure 3 It can be seen that the pitch angle error can smoothly converge to 0 degrees, and the overshoot does not exceed 4 degrees; from Figure 4 It can be seen that the maximum value of the pitch angular velocity signal of the reusable launch vehicle is less than 30°, and no flutter is observed in the angular velocity; Figure 8 As can be seen, although the control quantity fluctuates, the maximum value does not exceed 0.6, thus meeting engineering requirements; moreover, the fluctuation does not cause attitude angle jitter in reusable vehicles. Therefore, the experimental results demonstrate that this invention has significant engineering application value.

Claims

1. A reusable launch vehicle control method based on an elliptic disturbance observer, characterized by the following steps: Step S10: Install an angle-measuring gyroscope on the reusable launch vehicle to measure the pitch angle signal. Then, set the desired pitch angle signal according to the flight mission and compare it to obtain the pitch angle error signal. Next, perform a nonlinear half-power integral operation on the pitch angle error signal to obtain the pitch angle error half-power integral signal. Install a velocity-measuring gyroscope on the reusable launch vehicle to measure the pitch angular velocity signal. Then, superimpose the pitch angle error signal and the pitch angle error half-power integral signal to form a combined pitch angle error signal. Next, design a first-order differential filter to obtain an approximate differential pitch angular velocity signal from the pitch angular velocity signal. Finally, construct the observer state differential signal based on the pitch angle error signal, the approximate differential pitch angular velocity signal, and the interference observation control signal as follows: ； ； ； ； ； in To reuse the launch vehicle's pitch angle signal, For the desired pitch angle signal, This is the pitch angle error signal; For constant time parameters of the integral, For constant parameters of the semi-power transformation, This is a constant integration threshold parameter; The pitch angle error is a half-power integral signal; This is the pitch angular velocity signal of the repetitive launch vehicle; , For constant combination parameters, This is the pitch angle combination error signal; These are the constant parameters of the first-order filter differentiator. The differential operator is the transfer function of the filter differentiator; This is the approximate differential signal of the pitch angular velocity; These are the constant parameters of the observer. To prevent interference with the observation and control signal, the initial value is set to 0. The observer state differential signal; Step S20: Integrate the differential signal of the observer state to obtain the observer state signal; then superimpose the pitch angle combined error signal to obtain the comprehensive observer state signal; then perform a limiting transformation on the comprehensive observer state signal to obtain the observation state limiting signal; then perform an elliptic transformation on the observation limiting signal to obtain the observation state elliptic transformation signal; finally perform an inverse proportional transformation on the observation state elliptic transformation signal to obtain the observation state inverse elliptic proportional signal as follows: ； ； ； ； ； in For observer state signals; This is the overall state signal of the observer; , The limiting parameter is a constant value; Amplitude limiting signal for observation status; These are constant elliptic transformation parameters; The elliptic transformation signal for the observation state; It is a constant inverse proportional parameter. The inverse proportional signal of the observed ellipse; Step S30: Based on the observed state elliptic inverse ratio signal, the observer's comprehensive state signal, and the pitch angle error signal, the pitch error compensation rate signal is solved using adaptive and semi-power transformation and coincidence function switching; then, a nonlinear semi-power integration is performed to obtain the pitch error compensation signal; based on the observed state elliptic inverse ratio signal, the observer's comprehensive state signal, and the pitch angle velocity signal, the pitch velocity compensation rate signal is solved using adaptive and semi-power transformation and coincidence function switching; then, a nonlinear semi-power integration is performed to obtain the pitch velocity compensation signal as follows; ； ； ； ； in For symbolic functions, For constant parameters, This is the threshold parameter for the integral constant. This is a constant parameter used to adjust the convergence speed of the pitch error compensation signal; This is the pitch error compensation rate signal; This is the pitch error compensation signal; For constant parameters, This is a constant parameter used to adjust the convergence speed of the pitch speed compensation signal; This is the pitch speed compensation rate signal; For pitch speed compensation signal; Step S40: An interference observation control signal is obtained by superimposing the pitch error compensation signal, pitch speed compensation signal, observer integrated status signal, and observation status elliptic inverse ratio signal. Then, a limiting transformation is performed on the pitch angle combined error signal to obtain a pitch angle combined error limiting signal. Next, an elliptic transformation is performed on the pitch angle combined error limiting signal to obtain a pitch angle elliptic transformation signal. Finally, an inverse proportional transformation is performed on the pitch angle elliptic transformation signal to obtain the pitch angle elliptic inverse ratio signal as follows: ； ； ； ； Among them To interfere with the observation and control signals, , It is a constant parameter; This is a pitch angle combination error limiting signal; This is an elliptic transform signal for the pitch angle; This is the pitch angle elliptic inverse ratio signal; Step S50: The pitch angle combined error elliptic crossover signal is obtained by sign transformation of the pitch angle combined error elliptic inverse signal and the pitch angle combined error signal; then, the pitch angle combined error elliptic crossover signal and the pitch angle combined error limiting signal are combined to obtain the pitch angle elliptic limiting signal; next, the pitch angle combined error integral signal is obtained by nonlinear half-power integration of the pitch angle elliptic limiting signal and the pitch angle combined error signal; finally, the interference observation control signal, the pitch angle combined error signal, the pitch angle combined error elliptic crossover signal, and the pitch angle elliptic limiting signal are superimposed to obtain the final pitch control signal of the repeating launch vehicle, achieving stable tracking control of the desired pitch angle as follows: ； ； ； ； in The ellipse symbol crossover signal represents the pitch angle combination error. This is an elliptical amplitude-limited signal for pitch angle; For constant threshold parameters of integration, This is the integral signal of the pitch angle combination error; , , For constant control parameters, This is the final pitch control signal for the reusable launch vehicle.

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