Adaptive gain scheduling control method for reusable vehicle

Abstract

This invention discloses an adaptive gain scheduling control method for a reusable vehicle. Based on the real-time estimation and compensation of uncertainties and disturbances by the ESO, this method enables precise attitude control of the reusable vehicle (RLV) under unmodeled dynamics, unknown external disturbances, and channel coupling. The estimator's classification compensation mechanism for disturbances enables adaptive scheduling of control gains during cross-domain maneuvers. Adaptive compensation is performed based on a nominal controller, and the scheduling range is designed based on prior information to ensure the stability of the proposed controller. This invention improves the attitude control performance and anti-interference capability of RLV cross-domain recovery, demonstrating excellent adaptability and robustness.

Description

Technical Field

[0001] The present invention relates to the field of aerospace vehicle control technology, and in particular to an estimation and compensation-based adaptive gain scheduling control method for a reusable vehicle. Background Art

[0002] A reusable launch vehicle (RLV) is a type of aircraft that, after completing a scheduled launch mission, can perform another launch mission after inspection, maintenance, and refueling. The vertical take-off and landing scheme inherits the configuration of traditional launch vehicles and has advantages such as technological span and low R&D costs. However, the airspace and speed domain span of the RLV vertical return flight are large, the dynamic pressure changes dramatically, the flight environment is complex and changeable, and there are strong internal and external uncertainties and disturbances such as aerodynamic parameter deviations, structural and wind interference. Each channel exhibits severe nonlinear coupling characteristics. Especially when the internal parameters of the system change or severe external disturbances occur, traditional control theory is difficult to meet the high-performance control requirements under the special maneuvers of modern launch vehicles.

[0003] Precise attitude control during vertical landing is crucial for achieving safe vehicle recovery. Currently, most engineering projects employ gain scheduling methods for vehicle attitude control, employing classic control methods such as PID. However, simple linear control methods are unable to cope with the strong nonlinear coupling, unknown disturbances, and uncertainties in the system, making it difficult to achieve satisfactory control results. With the advancement of modern technology, advanced control theories such as robust control, sliding mode control, adaptive backstepping control, and disturbance observer-based control methods have been developed for RLV attitude control.

[0004] Robust control quantitatively analyzes uncertainty and designs a controller to suppress the impact of uncertainty. ∞ Robust control methods can address uncertainties caused by uncertain aerodynamic parameters and liquid fuel sloshing, thereby enabling robust attitude control design for RLVs. Sliding mode control designs the system's switching hyperplane based on the system's desired dynamic characteristics, effectively addressing parameter uncertainty and external disturbances. Because traditional sliding mode control methods based on linear sliding surfaces struggle to avoid chattering of the controlled variable, terminal sliding mode control has gradually developed, achieving rapid control system convergence while also addressing the much-discussed chattering issue. Non-singular terminal sliding mode control further addresses the singularity issue of traditional terminal sliding mode control, promoting the application of sliding mode control technology in aircraft control. Furthermore, adaptive backstepping control decomposes a nonlinear control system into several subsystems that do not exceed the system order. Stable virtual controllers are then designed for each subsystem, and Lyapunov functions are then used to perform a step-by-step backstepping to ultimately obtain a controller that stabilizes the entire system. Due to the multi-layer recursive nature of this method, the designed controller is extremely complex.

[0005] In contrast, control concepts based on disturbance estimation and compensation are more intuitive and offer significant advantages in handling system disturbances and uncertainties. Examples include unknown input observers, disturbance observers, generalized proportional-integral observers, uncertainty and disturbance estimators, and extended state observers (ESOs). ESO design requires minimal dynamic system information, has a simple and easy-to-design structure, and can estimate both disturbances and system states, garnering widespread attention in the control field.

[0006] However, during re-entry, the cross-domain maneuvers of a reusable vehicle (RLV) within a large airspace cause the vehicle's inherent characteristics and the external flight environment to vary across the airspace and velocity domains, resulting in complex and variable disturbance types in the ESO estimate. Different disturbance types have varying impacts on the system, and inappropriate compensation mechanisms can be counterproductive, impacting control performance and stability margins. Currently, research on control methods specifically tailored to cross-domain maneuverability is lacking. Summary of the Invention

[0007] The purpose of the present invention is to provide a reusable vehicle adaptive gain scheduling attitude control method based on a strategy combining an observer and an estimator to address the unmodeled dynamics, uncertainties and disturbances, such as the wide airspace spanned by RLV re-entry flight, large changes in air density, flight speed and dynamic characteristics, severe coupling between channels, fuel consumption and large swaying, and changes in aircraft structure. The method is applied to the attitude control of the reusable vehicle re-entering the atmosphere, so as to solve the control gain scheduling problem of the RLV cross-domain maneuvering process in a large airspace, thereby realizing the safe recovery of the RLV.

[0008] The technical solution adopted to achieve the purpose of the present invention is:

[0009] A method for adaptive gain scheduling control of a reusable vehicle comprises the following steps:

[0010] S1. Based on the trajectory change requirements during the RLV reentry flight, a guidance law is designed for the RLV flight attitude to generate corresponding attitude tracking commands. The guidance commands for the pitch, roll, and yaw channels are:

[0011]

[0012] θ is the ballistic inclination angle, α r is the angle of attack guidance law, is the pitch angle command, β r is the sideslip angle command, γ r is the roll angle command; set the sideslip angle command β r =0, used to achieve yaw angle control ψ r =ψv , ψ r is the yaw angle, ψ v is the ballistic deflection angle,

[0013] S2. Design a six-degree-of-freedom dynamic model for the RLV reentry flight process, taking into account unmodeled dynamics, uncertainties, and disturbances, including air density, flight speed, and dynamic characteristics changes during cross-domain maneuvers, inter-channel coupling, fuel consumption, large oscillations, and vehicle structural changes. Establish an RLV attitude control model under these disturbances and uncertainties.

[0014] The six-degree-of-freedom dynamic model is:

[0015] The dynamic equations of the RLV center of mass motion are:

[0016]

[0017] The dynamic equation for the RLV's rotation around the center of mass is:

[0018]

[0019] Kinematic equations for the motion of the RLV center of mass:

[0020]

[0021] Kinematic equations for the rotation of the RLV around its center of mass

[0022]

[0023] Where m is the mass of the RLV, g is the acceleration due to gravity, α and β are the angle of attack and sideslip respectively, ψ,γ are the pitch angle, yaw angle and roll angle respectively, θ,ψ V ,γ V are respectively the ballistic inclination angle, ballistic deviation angle and tilt angle, V is the displacement velocity, x, y, z are the position coordinates, ω x ,ω y ,ω z is the angular velocity, J x ,J y ,J z is the moment of inertia, M x ,M y ,M z are the components of the external torque vector on each axis of the projectile coordinate system, X, Y, Z are drag, lift and side force respectively;

[0024]

[0025] in, is the dynamic pressure, ρ is the air density at the flight altitude of the RLV, S is the characteristic area of ​​the RLV, Lb ,L c are the lateral and longitudinal reference lengths of the RLV, respectively, and c x ,c y ,c z are respectively the drag coefficient, lift coefficient and side force coefficient, m x ,m y ,m z Represent the rolling moment coefficient, yaw moment coefficient, and pitch moment coefficient respectively;

[0026] Considering the RLV characteristics and various uncertainties and disturbances of the return flight, Taking the second derivative of ψ and γ, we can establish the following attitude control model:

[0027]

[0028] in, b f ,b p ,b r Represents the control gain of the pitch channel, yaw channel, and roll channel, are the moment coefficient components of the pitch channel, yaw channel and roll channel respectively, is the static derivative, δ z ,δ y ,δ x Mathematical rudders to be designed for the pitch, yaw, and roll channels;

[0029] The state information of the pitch channel, yaw channel and roll channel except the rudder effect is defined as disturbance f1, f2, f3, and f1 = f 01 +d1,f2=f 02 +d2,f3=f 03 +d3,f 01 ,f 02 ,f 03 are the modeled dynamics, and d1, d2, and d3 contain the remaining unmodeled dynamics, uncertainties, and unknown external disturbances in the pitch, yaw, and roll channels;

[0030]

[0031] S3. Use ESO to estimate the integrated total disturbance of pitch, roll, and yaw channels in real time and perform feedback compensation;

[0032] Use the angular velocity information ω of the three channels of pitch, yaw and roll respectively z ,ω y ,ω x The ESO is designed to estimate the total disturbance in real time. The ESOs designed for the pitch channel, yaw channel, and roll channel are

[0033]

[0034]

[0035] in, are the estimated angular velocities of the pitch channel, yaw channel, and roll channel, respectively. z ψ1 ≈ω y ,z γ1 ≈ω x , are the total disturbance estimates of the pitch channel, yaw channel and roll channel, i.e. z θ2 ≈f1+(b f -b f0 )δ z , z ψ2 ≈f2+(b p -b p0 )δ y , z γ2 ≈f3+(b r -b r0 )δ x , b f0 ,b p0 ,b r0 for b f ,b p ,b r Estimated nominal value of

[0036] Place the ESO pole at -ω oz ,-ω oy ,-ω ox Department, ω oz ,ω oy ,ω ox are the pitch, yaw and roll channel bandwidths, and the six observer gains l z1 ,l z2 ,l y1 ,l y2 ,l x1 ,l x2 satisfy

[0037] S4. Considering the continuous changes in system gain and uncertainty caused by the dynamic characteristics and aerodynamic parameters during RLV cross-domain maneuvers, a symbolic estimator is used to classify and identify the disturbances and uncertainties of RLV cross-domain maneuvers, and their respective compensations are performed based on the nominal controller to achieve precise attitude control during RLV reentry flight.

[0038] The symbolic estimator is used to analyze, estimate and compensate for disturbances and uncertainties. The loss function established is:

[0039]

[0040] Among them, δ bf ,δ bp ,δ br are the pitch, yaw and roll channel system gains b respectively f ,b p ,b r The estimated uncertainty of f θ ,f ψ ,f r is the disturbance and uncertainty that is unrelated to the steering effect; the loss function is solved by using the symbolic projection gradient strategy, and we get:

[0041]

[0042] Among them, δ bf ,δ bp ,δ br are the estimated uncertainties of the rudder effects in the pitch, yaw and roll channels, f ψ ,f γ are the estimated values ​​of disturbances and uncertainties unrelated to the rudder effect in the pitch, yaw and roll channels, respectively; α1, α2, α3>0 are the update constants to be designed for the pitch, yaw and roll channels, respectively;

[0043] Based on the estimation results and the attitude angle and angular rate information of the three channels, the mathematical rudder control laws for the pitch, yaw, and roll channels are designed as follows:

[0044]

[0045] Among them, k pf ,k pp ,k pr are the proportional feedback gains of the pitch, yaw and roll channels, respectively, k df ,k dp ,k dr is the differential feedback gain of the three channels;

[0046] By mathematical rudder δ x ,δ y ,δ z The equivalent grid rudders of the three channels of pitch, yaw and roll are obtained as follows:

[0047]

[0048] The three-channel equivalent grid rudder is applied to the six-degree-of-freedom model of the RLV to achieve precise tracking guidance law of pitch angle, sideslip angle and roll angle, namely ψ=ψ r =ψ V(β=0),γ=γ r =0, perform attitude control for RLV cross-domain maneuvers.

[0049] The present invention designs an adaptive gain scheduling control strategy for RLV, which estimates and separates disturbances such as strong coupling between channels, parameter and model uncertainties in cross-domain maneuvers in real time, and can effectively improve the attitude control accuracy of cross-domain maneuvers.

[0050] The present invention performs adaptive gain scheduling design based on the nominal controller, which solves the control gain selection problem in the traditional ADRC controller. It has a simple structure and is easy to design. It ensures the stability of attitude control under cross-domain maneuvers, while improving the stability margin of the control system and having stronger robustness and adaptability. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 Schematic diagram of the adaptive gain scheduling control method for a reusable vehicle according to the present invention.

[0052] Figure 2 This is a cross-domain maneuvering altitude profile of the RLV of the present invention.

[0053] Figure 3 This is the speed change curve of the RLV cross-domain maneuver of the present invention.

[0054] Figure 4 This is the three-channel attitude angle tracking curve of the present invention.

[0055] Figure 5 This is the three-channel attitude angular velocity change curve of the present invention.

[0056] Figure 6 These are the control torque curves of the three mathematical rudders of the present invention. DETAILED DESCRIPTION

[0057] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0058] The present invention's reusable vehicle adaptive gain scheduling control method, based on the real-time estimation and compensation of uncertainties and disturbances by the ESO, can achieve precise attitude control of the RLV under unmodeled dynamics, unknown external disturbances, and channel coupling. Based on the estimator's classification compensation mechanism for disturbances, adaptive scheduling of control gains during cross-domain maneuvers can be achieved. To ensure the stability of the proposed controller, adaptive compensation is performed based on the nominal controller, and the scheduling range is designed based on prior information. The present invention improves the attitude control performance and anti-interference capability of the RLV cross-domain recovery, and has good adaptability and robustness.

[0059] like Figure 1 As shown, the adaptive gain scheduling control method for a reusable vehicle according to an embodiment of the present invention comprises the following steps:

[0060] Step 1: Based on the trajectory change requirements of the RLV reentry flight process, design an appropriate guidance law for the RLV flight attitude to generate corresponding attitude tracking commands;

[0061] Step (1) During the RLV reentry flight, its flight altitude and Mach number gradually decrease. Therefore, the longitudinal height profile is designed to be h r ,

[0062]

[0063] Among them, t0, t1, t2, h 01 ,h 02 , a1 is the constant to be designed, t0 is the initial time value, t1, t2 are the function segmentation times, h 01 is the initial altitude of the reentry flight, h 02 is the terminal altitude of the reentry flight, a1 is the coefficient of the piecewise function,

[0064] For the pitch channel, the angle of attack guidance law α is designed according to the current true altitude h of the RLV reentry flight process r for:

[0065]

[0066] The saturation function is defined as e h =h r -h is the height tracking error, h i ,k pα ,k dα is the constant to be designed, h i is the height error, k pα is the proportionality coefficient, k dα is the differential coefficient, and α0 is the initial value of the angle of attack.

[0067] Considering that the inertial time constant of the trajectory inclination angle θ is much larger than and the time constant of α, according to the geometric relationship The angle of attack guidance law α r Converted to approximately equivalent pitch angle command

[0068]

[0069] For the yaw channel, the yaw command is set to ψ r =ψ v, that is, the yaw angle tracks the trajectory angle. When high-precision instruction tracking is used, β control can basically be achieved, so the sideslip angle instruction is set to β r = 0 to achieve yaw angle control ψ r =ψ v .

[0070] For the roll channel, the roll angle tracking is set to γ r =0.

[0071] Therefore, the guidance instructions for the three channels are set as follows:

[0072]

[0073] Step 2: Design a six-degree-of-freedom dynamic model for the RLV reentry flight process, fully considering the changes in air density, flight speed, and dynamic characteristics during cross-domain maneuvers, the strong coupling between channels, as well as unmodeled dynamics, uncertainties, and disturbances such as fuel consumption, large sloshing, and vehicle structure changes. Establish an RLV attitude control model under disturbances and uncertainties.

[0074] Among them, the established RLV six-degree-of-freedom model is:

[0075] The dynamic equations of the RLV center of mass motion are:

[0076]

[0077] The dynamic equation for the RLV's rotation around the center of mass is:

[0078]

[0079] Kinematic equations for the motion of the RLV center of mass:

[0080]

[0081] Kinematic equations for the RLV's rotation around its center of mass:

[0082]

[0083] Where m is the mass of the RLV, g is the acceleration due to gravity, α and β are the angle of attack and sideslip respectively, ψ,γ are the pitch angle, yaw angle and roll angle respectively, θ,ψ V ,γ V are respectively the ballistic inclination angle, ballistic deviation angle and tilt angle, V is the displacement velocity, x, y, z are the position coordinates, ω x ,ω y ,ω z is the angular velocity, J x ,J y ,J z is the moment of inertia, Mx ,M y ,M z are the components of the external torque vector on each axis of the missile coordinate system, X, Y, and Z are drag, lift, and side force respectively. Using the aerodynamic coefficient formula of the public Winged-Cone model, we have:

[0084]

[0085] in, is the dynamic pressure (ρ is the air density at the flight altitude of the RLV), S is the characteristic area of ​​the RLV, and L b ,L c are the lateral and longitudinal reference lengths of the RLV, respectively. x ,c y ,c z are respectively the drag coefficient, lift coefficient and side force coefficient, m x ,m y ,m z These six aerodynamic coefficients, representing the roll moment coefficient, yaw moment coefficient, and pitch moment coefficient, can be calculated in real time using publicly available Winged-Cone model data.

[0086] Considering the inherent characteristics of RLV and various uncertainties and disturbances of return flight, the equation (6) The second derivative of ψ and γ is performed to establish the following attitude control model:

[0087]

[0088] in, b f ,b p ,b r Represents the control gain of the pitch channel, yaw channel, and roll channel, are the main moment coefficient components of the pitch channel, yaw channel and roll channel respectively, is the static derivative, which is related to the angle of attack and Mach number, δ z ,δ y ,δ x is the mathematical rudder to be designed for the pitch channel, yaw channel and roll channel. In addition, the state information of the pitch channel, yaw channel and roll channel except the rudder effect is defined as disturbance f1, f2, f3, and f1 = f 01 +d1,f2=f 02 +d2,f3=f 03 +d3,f 01 ,f 02 ,f 03are the modeled dynamics, and d1, d2, and d3 include the remaining unmodeled dynamics, uncertainties, and unknown external disturbances in the pitch, yaw, and roll channels:

[0089]

[0090] It can be seen that the modelable disturbance f of the three channels of pitch, yaw and roll is 01 ,f 02 ,f 03 Including inter-channel coupling, aerodynamic parameter uncertainty, etc. Uncertain disturbances f1, f2, f3 and system gain b f ,b p ,b r It is a key issue to be solved in the RLV three-channel attitude control.

[0091] Step 3: To effectively handle the inter-channel coupling, unmodeled dynamics, and unknown external disturbances in RLV attitude control, the ESO is used to estimate the integrated total disturbance of the pitch, roll, and yaw channels in real time and perform feedback compensation.

[0092] In order to reduce the inter-channel coupling (aerodynamic coupling, inertial coupling, control quantity coupling), parameter and model uncertainty, and other unknown external disturbances in f1, f2, f3, the angular velocity information ω of the pitch, yaw, and roll channels is used respectively. z ,ω y ,ω x The ESO is designed to estimate the total disturbance in real time. Based on (7), the ESOs designed for the pitch channel, yaw channel, and roll channel are:

[0093]

[0094] in, are the estimated angular velocities of the pitch channel, yaw channel, and roll channel, respectively. z ψ1 ≈ω y ,z γ1 ≈ω x , are the total disturbance estimates of the pitch channel, yaw channel and roll channel, i.e. z θ2 ≈f1+(b f -b f0 )δ z , z ψ2 ≈f2+(b p -b p0 )δ y , z γ2 ≈f3+(b r -b r0 )δ x . b f0,b p0 ,b r0 for b f ,b p ,b r Estimated nominal value.

[0095] To ensure the convergence of the observer, the ESO pole is placed at -ω oz ,-ω oy ,-ω ox Department, ω oz ,ω oy ,ω ox are the pitch, yaw and roll channel bandwidths respectively. At this time, the six observer gains l z1 ,l z2 ,l y1 ,l y2 ,l x1 ,l x2 satisfy

[0096] Considering the continuous changes in system gain caused by the coupling between channels and uncertain aerodynamic parameters during RLV cross-domain maneuvers, it is difficult for the traditional single control gain method to achieve satisfactory attitude control effects. Although ADRC technology has strong robustness and anti-interference capabilities, the control gain b of the three channels of pitch, yaw and roll is not stable. f ,b p ,b r As a very critical parameter in ADRC, it not only affects the compensation accuracy of disturbances, but also directly affects the stability margin of the control system. Therefore, an adaptive gain scheduling strategy is adopted to compensate disturbances and gains in real time.

[0097] Step 4: Considering the continuous changes in system gain and uncertainty caused by the dynamic characteristics and aerodynamic parameters during RLV cross-domain maneuvers, a symbolic estimator is used to classify and identify the disturbances and uncertainties of the RLV cross-domain maneuvers, and the nominal controller is used to compensate for them respectively to achieve precise attitude control during RLV reentry flight.

[0098] The symbolic estimator is used to analyze, estimate and compensate for disturbances and uncertainties, and the loss function is established as

[0099]

[0100]

[0101] Among them, δ bf ,δ bp ,δ br are the pitch, yaw and roll channel system gains b respectively f ,b p ,b r The uncertainty of the estimate, f ψ ,f r is the disturbance and uncertainty that is unrelated to the steering effect. To minimize the loss function, the symbolic projection gradient strategy is used to solve (11)-(13), and we get:

[0102]

[0103] Among them, δ bf ,δ bp ,δ br are the estimated uncertainties of the rudder effects in the pitch, yaw and roll channels, f ψ ,f γ are the estimated values ​​of disturbances and uncertainties unrelated to the rudder effect in the pitch, yaw and roll channels, respectively. α1, α2, α3>0 are the update constants to be designed for the pitch, yaw and roll channels, respectively.

[0104] Based on the estimation results (14)-(16) and the attitude angle and angular rate information of the three channels, the mathematical rudder control laws for the pitch, yaw and roll channels are designed as follows:

[0105]

[0106] Among them, k pf ,k pp ,k pr are the proportional feedback gains of the pitch, yaw and roll channels, respectively, k df ,k dp ,k dr is the differential feedback gain of the three channels. The design converts the three channels into a series integral form that is easy to control by estimating, compensating for disturbances and controlling gains respectively.

[0107] During the RLV aerodynamic deceleration phase, only the grid rudder works. At this time, the mathematical rudder δ x ,δ y ,δ z The equivalent grid rudders of the pitch, yaw and roll channels are obtained as follows:

[0108]

[0109] Applying the three-channel equivalent grid rudder (20) to the six-degree-of-freedom model of the RLV can achieve accurate tracking guidance law of pitch angle, sideslip angle and roll angle, namely, ψ=ψ r =ψ V (β=0),γ=γ r =0.

[0110] Therefore, the RLV attitude control based on the adaptive gain scheduling control laws (17)-(19) of the pitch, yaw and roll channels can realize the adaptive scheduling of the system gain during the cross-domain maneuvering process, thereby improving the attitude control performance of the cross-domain maneuvering.

[0111] The present invention comprehensively considers the unmodeled dynamics, uncertainties and disturbances such as the wide cross-domain airspace and speed range, large changes in air density, flight speed and dynamic characteristics, severe coupling between channels, fuel consumption and large swaying, and changes in aircraft structure during RLV re-entry flight. An adaptive gain scheduling control strategy is proposed. Based on the active disturbance rejection controller, the signed projection gradient strategy is used to adaptively schedule the system gain. The strategy does not rely on RLV feature point extraction, has a simple structure and is easy to design. It can effectively handle the uncertainties and disturbances of the RLV cross-domain maneuvering process, thereby improving the attitude control accuracy.

[0112] To verify the effectiveness of the adaptive gain-scheduling control strategy proposed in this paper, a six-degree-of-freedom RLV model was constructed using MATLAB software. Based on the attitude control model, an adaptive gain-scheduling control strategy was designed to demonstrate the effectiveness of the present invention in handling disturbances and uncertainties, as well as its robustness and adaptability in improving attitude control accuracy. The relevant parameters used in the simulation are as follows:

[0113] t0=0,t1=60,t2=120,h 01 =25000,h 02 =1000, height error h1=500, h2=50, proportional coefficient k pα =0.2, differential coefficient k dα =1, the initial value of the angle of attack α0 = 5. The total mass of the RLV aircraft is 136080 kg, the longitudinal reference length is 24.384 m, the lateral reference length is 18.288 m, and the reference area is 334.73 m 2 , the initial moment of inertia in the x direction is 1355818kg×m 2 , the initial moment of inertia in the y and z directions is 13558180 kg×m 2 .

[0114] ω of =10,b f0 =2.45,ω op =10,b p0 =0.5,ω or =10,b r0 =11.18. bf ,δ bp ,δ br and f ψ ,f γThe initial values ​​of are all set to 0, α1, α2, α3 = 0.001. pf =42,k df =20,k pp =0.5,k dp =20,k pr =62,k dr = 38. The initial value of the control attitude angle is [5 0 1]°, the initial value of the position is [0 25000 0]m, the initial value of the speed is 4Ma, and the initial value of the angular velocity is 0.

[0115] The simulation results are as follows Figure 2-6 As shown, it is divided into two parts:

[0116] Part I: Guidance Law

[0117] According to the longitudinal profile reference value of the RLV re-entry flight, the angle of attack is designed, and the pitch angle tracking control is performed according to the geometric relationship. The obtained longitudinal profile reference value and actual value are as follows Figure 2 As shown in Figure 2, it can be seen that the control strategy proposed in the present invention can track the longitudinal profile value well and has good tracking performance. Figure 3 As shown, the attenuation of the flight speed during the RLV re-entry flight is achieved, which further illustrates the effectiveness of the guidance law adopted by the present invention and lays a good foundation for achieving precise attitude control.

[0118] Part 2: Posture Control

[0119] The present invention proposes to use adaptive gain scheduling strategy to perform RLV cross-domain maneuvers. The simulation results show that Figure 4 The control result of the attitude angle is given. Figure 5 The control results of three angular velocities are given. Figure 6 This is a mathematical control rudder designed based on the present invention. The results show that the present invention can effectively handle uncertainties such as inter-channel coupling, aerodynamic parameter uncertainty, and air density variations. It also achieves stable and precise tracking of the guidance law, demonstrating the effectiveness, robustness, and adaptability of the proposed algorithm.

[0120] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is limited by the appended claims rather than the above description, and it is intended that all changes that fall within the meaning and scope of the equivalent elements of the claims are included in the present invention.

[0121] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A method for adaptive gain scheduling control of a reusable vehicle, characterized in that: Including steps: S1. Based on the trajectory change requirements during the RLV reentry flight, a guidance law is designed for the RLV flight attitude to generate corresponding attitude tracking commands. The guidance commands for the pitch, roll, and yaw channels are: θ is the ballistic inclination angle, α r is the angle of attack guidance law, θ r is the pitch angle command, β r is the sideslip angle command, γ r is the roll angle command; set the sideslip angle command β r =0, used to achieve yaw angle control ψ r =ψ v , ψ r is the yaw angle, ψ v is the ballistic deflection angle; S2. Design a six-degree-of-freedom dynamic model for the RLV reentry flight process, taking into account unmodeled dynamics, uncertainties, and disturbances, including air density, flight speed, and dynamic characteristics changes during cross-domain maneuvers, inter-channel coupling, fuel consumption, large oscillations, and vehicle structural changes. Establish an RLV attitude control model under these disturbances and uncertainties. The six-degree-of-freedom dynamic model is: The dynamic equations of the RLV center of mass motion are: The dynamic equation for the RLV's rotation around the center of mass is: Kinematic equations for the motion of the RLV center of mass: Kinematic equations for the rotation of the RLV around its center of mass Where m is the mass of the RLV, g is the acceleration due to gravity, α and β are the angle of attack and sideslip, respectively. are the pitch, yaw and roll angles, θ, ψ V , γ V are respectively the trajectory inclination angle, trajectory deviation angle and tilt angle, V is the displacement velocity, x, y, z are the position coordinates, ω x ,ω y ,ω z is the angular velocity, J x , J y , J z is the moment of inertia, M x , M y , M z are the components of the external torque vector on each axis of the projectile coordinate system, X, Y, Z are drag, lift and side force respectively; in, is the dynamic pressure, ρ is the air density at the flight altitude of the RLV, S is the characteristic area of ​​the RLV, L b , L c are the lateral and longitudinal reference lengths of the RLV, respectively, and c x , c y , c z are respectively the drag coefficient, lift coefficient and side force coefficient, m x , m y , m z Represent the rolling moment coefficient, yaw moment coefficient, and pitch moment coefficient respectively; Considering the RLV characteristics and various uncertainties and disturbances of the return flight, Taking the second derivative of Ψ and γ, we can establish the following attitude control model: in, b f , b p , b r Represents the control gain of the pitch channel, yaw channel, and roll channel, are the moment coefficient components of the pitch channel, yaw channel and roll channel respectively, is the static derivative, δ z , δ y , δ x Mathematical rudders to be designed for the pitch, yaw, and roll channels; The state information of the pitch channel, yaw channel and roll channel except the rudder effect is defined as disturbance f1, f2, f3, and f1 = f 01 +d1,f2=f 02 +d2,f3=f 03 +d3,f 01 , f 02 , f 03 are the modeled dynamics, d1, d2, and d3 contain the remaining unmodeled dynamics, uncertainties, and unknown external disturbances in the pitch, yaw, and roll channels; S3. Use ESO to estimate the integrated total disturbance of pitch, roll, and yaw channels in real time and perform feedback compensation; Use the angular velocity information ω of the three channels of pitch, yaw and roll respectively z ,ω y ,ω x The ESO is designed to estimate the total disturbance in real time. The ESOs designed for the pitch channel, yaw channel, and roll channel are in, are the estimated angular velocities of the pitch channel, yaw channel, and roll channel, respectively. are the total disturbance estimates of the pitch channel, yaw channel and roll channel, respectively, z ψ2 ≈f2+(b p -b p0 )δ y , z γ2 ≈f3+(b r -b r0 )δ x , b f0 , b p0 , b r0 for b f , b p , b r Estimated nominal value of Place the ESO pole at -ω oz , -ω oy , -ω ox Department, ω oz ,ω oy ,ω ox are the pitch, yaw and roll channel bandwidths, and the six observer gains l z1 , l z2 , l y1 , l y2 , l x1 , l x2 Satisfy z1 =2ω oz , l y1 =2ω oy , l x1 =2ω ox , S4. Considering the dynamic characteristics of the RLV cross-domain maneuver and the continuous changes in system gain and uncertainty caused by aerodynamic parameters, a symbolic estimator is used to classify and identify the disturbances and uncertainties of the RLV cross-domain maneuver, and the nominal controller is used to compensate for them respectively to achieve precise attitude control of the RLV reentry flight. The symbolic estimator is used to analyze, estimate and compensate for disturbances and uncertainties, and the loss function established is: Among them, δ bf , δ bp , δ br are the pitch, yaw and roll channel system gains b respectively f , b p , b r The uncertainty of the estimate, is the disturbance and uncertainty that is unrelated to the steering effect; the loss function is solved by the symbolic projection gradient strategy, and the result is: Among them, δ bf , δ bp , δ br are the estimated uncertainties of the rudder effects in the pitch, yaw and roll channels, are the estimated values ​​of disturbances and uncertainties unrelated to the rudder effect in the pitch, yaw and roll channels, respectively; α1, α2, α3>o are the update constants to be designed for the pitch, yaw and roll channels, respectively; Based on the estimation results and the attitude angle and angular rate information of the three channels, the mathematical rudder control laws for the pitch, yaw, and roll channels are designed as follows: Among them, k pf , k pp , k pr are the proportional feedback gains of the pitch, yaw and roll channels, respectively, k df , k dp , k dr is the differential feedback gain of the three channels; By mathematical rudder δ x , δ y , δ z The equivalent grid rudders of the three channels of pitch, yaw and roll are obtained as follows: The three-channel equivalent grid rudder is applied to the six-degree-of-freedom model of the RLV to achieve precise tracking guidance law of pitch angle, sideslip angle and roll angle, namely Perform attitude control for RLV cross-domain maneuvers.

Images