Hypersonic Vehicle Model Research Articles

A New Airframe/Propulsion-Integrated Aerodynamic Testing Technology in Hypersonic Wind Tunnel

This article presents a new type of multicomponent force measurement system to measure lift force, drag force, and pitching moment in hypersonic wind tunnel, which called the suspension force-measuring system (SFMS). The SFMS does not occupy the installation space of the scramjet engine and other key functional components in the air-breathing hypersonic vehicle model. It solves the problem that the conventional aerodynamic force measurement technology occupies too much internal space of the hypersonic vehicle test model and dramatically reduces the design difficulty of scramjet propulsion system in the test model. The SFMS adopts the spatial multi-point distribution support mode for the test model. Therefore, it has an excellent stiffness characteristic, meeting the requirement of support rigidity of wind tunnel force measurements test for large-scale and heavy load test model. Then the designed SFMS is constructed and calibrated. The static calibration results show that each test channel of the SFMS has a good sensitivity of 0.2502 mV/N for drag force test channel, 0.1557 mV/N for lift force test channel, 0.2484 mV/Nm for pitching moment test channel, and the max interference error among the SFMS test channels is less than 2.3&#x0025;. A series of aerodynamic force experiments have been carried out in the <inline-formula> <tex-math notation="LaTeX">$\emptyset 600~mm$ </tex-math></inline-formula> impulse combustion wind tunnel, and the output data of each test channel well reflected the change process of the total pressure in the test section of wind tunnel. Hence, the proposed device can meet the force test requirements of the hypersonic wind tunnel test.

A new force-measuring balance for large-scale model in hypersonic wind tunnel.

There is a strong coupling effect between the body and propulsion system of the integrated hypersonic vehicle. The scaled-down model cannot reflect the laws of physics. Therefore, carrying out hypersonic aerodynamic tests using large-scale aircraft models is an urgent difficulty and the key link in the research of hypersonic aircraft. This Note presents a designscheme of large-scale and heavy-load three-component gauge strain balance. The balance innovatively uses the designof a "herringbone" force measuring element and a support plate to ensure the sensitivity of the main channel and solve the problem of serious coupling between channels. In order to solve the problem of insufficient stiffness caused by the large scale of the model, two convex plates are added to the contact surface between the model and the balance. Therefore, the difficulties encountered by large-scale aircraft models in a pulsed wind tunnel can be overcome effectively. The balance is verified by static calibration and wind tunnel test to meet the requirements. The results show that the balance meets the requirements of the aerodynamic load test of the large-scale and heavy-duty hypersonic vehicle model in a pulse combustion wind tunnel.

Optimization of Active and Passive Thermal Protection Systems for a Hypersonic Vehicle

The hypersonic vehicle model Michigan–AFRL Scramjet in Vehicle (MASIV) is used to optimize both the active and the passive thermal protection systems on a scramjet-powered generic X-43 waverider. The passive thermal protection system is the NASA ARMOR design; a silicon dioxide insulation layer is sandwiched between a radiation shield and the vehicle titanium skin. The active thermal protection system consists of a heat exchanger on the combustor wall; the coolant is the liquid hydrogen fuel. The portion of the fuel that is used for cooling (and not for propulsion) is recirculated back into the fuel tank, which causes the temperature of fuel in the tank to rise. Gradient-based optimization is performed to determine 1) the minimum insulation thickness distribution required and 2) the optimal coolant mass flow rate and its variation in time. Constraints are that surface temperatures cannot exceed the failure temperatures, and the volume of fuel in the fuel tank cannot exceed the tank volume. The hypersonic vehicle heat transfer model is adaptable and can handle new materials for thermal protection, as they are developed.

Global adaptive neural backstepping control of a flexible hypersonic vehicle with disturbance estimation

PurposeThis paper aims to discuss the precise altitude and velocity tracking control of a hypersonic vehicle, a global adaptive neural backstepping controller was studied based on a disturbance observer (DOB).Design/methodology/approachThe DOB combined with a radial basis function (RBF) neural network (NN) was used to estimate the disturbance terms that are generated by the flexible modes of the hypersonic vehicle system. A global adaptive neural method was introduced to approximate the unknown system dynamics, with robust control terms pulling the system transient states back into the neural approximation domain externally.FindingsThe globally uniformly ultimately bounded for all signals of a closed-loop system can be guaranteed by the proposed control algorithm. Additionally, the command filtered backstepping methods can avoid the explosion of the complexity problem caused by the backstepping design process. In addition, the effectiveness of the proposed controller can be verified by the simulation used in this study.Research limitations/implicationsNormally lateral dynamics issue should be discussed in the process of control system designed, the lateral dynamics are not included in the nonlinear dynamic model of hypersonic vehicle used in this paper, merely the longitudinal flight dynamics are discussed in this paper.Originality/valueThe flexible states in rigid modes are considered as the disturbance of the system, which is estimated by structuring DOB with NN approximations. The compensating tracking error and prediction error are used in the update law of RBF NN weight. The differential explosions complexity derived from the backstepping procedure is dealt with by using command filters.

Robust model predictive control for hypersonic vehicle with state‐dependent input constraints and parameter uncertainty

AbstractIn this article, a robust model predictive control strategy based on sum‐of‐squares (SOS‐RMPC) is proposed for hypersonic vehicle with state‐dependent input constraints and uncertain parameters. Based on feedback linearization model of hypersonic vehicle, the polytopic linear parameter varying error model with bounded disturbance is established for reference trajectory tracking. The real limits of the actual control inputs are transformed into the constraints of the virtual inputs equivalently with the state‐dependent nonlinear functions. Further, the multivariate linear fitting is used to approximate the state‐dependent input constraints into polynomials. A weighted composite virtual control is formulated as the combination of unconstrained control and auxiliary control. SOS technique is introduced to cast the polynomial constraints into the convex matrix SOS conditions via linear matrix inequality. The virtual control law can be obtained by solving a SOS‐RMPC convex optimization with infinite horizon. The invariant set is designed for the undisturbed error states and the norm‐bounding theory is applied to ensure that the predictive error states with disturbance can remain in the same invariant set. The real control law is obtained by inverse control. The simulation verifies the performance of the designed controller.

Compound control of an uncertain hypersonic vehicle model

The extremely broad flight envelope brings remarkable uncertainties to hypersonic vehicles. This paper investigates the longitudinal control problem of hypersonic vehicles with synthetical considerations on multiple modelling uncertainties, especially on time-varying aerodynamic coefficients. To overcome the efficiency loss of aerodynamic control surfaces (ACS), the reaction control system (RCS) is employed to assist the attitude control. An adaptive ACS-RCS compound control is proposed, which deals with uncertain RCS parameters, simultaneously. Other factors including scramjet input saturation, variable geometry inlet, external disturbances and structural flexibilities are also taken into account. Analysis and simulation indicate that preset references can be well tracked with prescribed performances.

Adaptive actuator fault-tolerant control for non-minimum phase air-breathing hypersonic vehicle model

In this paper, the tracking control problem of non-minimum phase flexible air-breathing hypersonic vehicles (AHSV) is investigated subject to actuator fault, external disturbances and parameters uncertainties. The study is began with a series of control-oriented manipulations: first, the input–output dynamics are derived by using feedback linearization method and the internal dynamics of AHSV are constructed; then, the zero dynamics stability analysis is conducted to verify the non-minimum phase characteristic of AHSV. In order to realize output tracking of the non-minimum phase system with sufficient accuracy, an adaptive fault tolerant controller (FTC) is proposed based on an output-redefinition making the zero-dynamics with respect to the new output stable. Additionally, robust adaptive laws are utilized for the estimation of unknown parameters and actuator failure compensation of the AHSV model. Furthermore, the stability of the closed-loop system is analyzed based on the Lyapunov stability theory. At last, the numerical simulation results are provided to demonstrate the effective tracking performance of the proposed FTC scheme.

Constrained fault-tolerant control for hypersonic vehicle subject to actuator failure and with unmeasurable states

In this article, a novel constrained fault-tolerant control (FTC) scheme is proposed to solve the attitude tracking control problem of the hypersonic vehicle (HSV) subject to multiple constraints, actuator faults, and disturbances. The reentry model of HSV with state constraints and the fault model of aerodynamic surface considering surface deflection constraints are constructed firstly. The adaptive robust unscented Kalman filter (ARUKF)-based estimation algorithm is designed, which can quickly estimate state variables, stuck faults, partial loss of effectiveness (PLOE) faults, and disturbances at the same time. By utilising the improved model predictive static programming (MPSP) technique, the complexity of processing multiple constraints and the computation are significantly reduced. Moreover, the closed-loop control system stability of HSV is analysed and the simulation results under two fault cases are given to demonstrate the effectiveness of the presented FTC scheme.

\({\mathcal{L}_1}\) Adaptive Loss Fault Tolerance Control of Unmanned Hypersonic Aircraft with Elasticity

This paper investigates the fault tolerance control of hypersonic aircrafts with L1 adaptive control method in the presence of loss of actuator effectiveness fault. The hypersonic model considers the uncertainties caused by the features of nonlinearities and couplings. Elasticity is taken into account in hypersonic vehicle modeling which makes the model more accurate. A velocity L1 adaptive controller and an altitude L1 adaptive controller are designed to control flexible hypersonic vehicle model with actuator loss fault. A PID controller is designed as well for comparison. Finally, the simulation results are used to analyze the effectiveness of the controller. Compared to the results of PID controller, L1 controllers have better performance.

A concise funnel robust model-free control mechanism for hypersonic space vehicles based on error driving

Based on non-affine models of hypersonic space vehicles, the tracking control problem of hypersonic vehicles is studied and analyzed in this article using funnel robust model-free control mechanism considering parametric uncertainty and external disturbances. First, the control system is decomposed into altitude subsystem and velocity subsystem. For altitude subsystem, we propose a concise funnel robust model-free control mechanism based on error driving, and a novel model transformation approach is applied to the controller design. The new model-free controller only contains a Hurwitz stable term and a filtering term, and does not need precise motion model and too much calculation, so it can improve the calculation speed of the system. For velocity subsystem, only a concise proportional-integral controller is needed to meet the tracking requirements. Moreover, the devised controller is capable of guaranteeing funnel performance on the altitude and velocity tracking errors. Finally, numerical simulation results are presented to verify the efficiency of the design.

Research on phase shift characteristics of electromagnetic wave in plasma

The phase shift characteristics reflect the state change of electromagnetic wave in plasma sheath and can be used to reveal deeply the action mechanism between electromagnetic wave and plasma sheath. In this paper, the phase shift characteristics of electromagnetic wave propagation in plasma were investigated. Firstly, the impact factors of phase shift including electron density, collision frequency and incident frequency were discussed. Then, the plasma with different electron density distribution profiles were employed to investigate the influence on the phase shift characteristics. In a real case, the plasma sheath around the hypersonic vehicle will affect and even break down the communication. Based on the hypersonic vehicle model, we studied the electromagnetic wave phase shift under different flight altitude, speed, and attack angle. The results indicate that the phase shift is inversely proportional to the flight altitude and positively proportional to the flight speed and attack angle. Our work provides a theoretical guidance for the further research of phase shift characteristics and parameters inversion in plasma.

Robust tracking for hypersonic vehicles subjected to mismatched uncertainties via fixed-time sliding mode control

This article investigates the robust tracking issue for the longitudinal dynamics of hypersonic vehicles subjected to mismatched uncertainties, and a novel sliding mode control approach is proposed to achieve the fixed-time convergence of tracking errors and satisfactory robustness against mismatched uncertainties. Establishing the control-oriented hypersonic vehicle model as velocity and altitude subsystems with mismatched uncertainties, the article introduces the nonlinear finite-time disturbance observer technique to estimate the uncertainties precisely. With the estimated uncertainties from the observer, the fixed-time sliding mode control is presented to track the velocity and altitude references. Consequently, the effect of the mismatched disturbances can be eliminated and the tracking performance can be improved. The stability of the closed-loop system is also analyzed. Numerical simulation results demonstrate the validity and superiority of the proposed control.

Beyond LOS Detection of Hypersonic Vehicles

RCS modeling of a typical hypersonic vehicle and its plasma sheath was investigated. The plasma parameters were analyzed to determine which were most dominant for accurate RCS prediction. HF was determined to provide BLOS detection and good conductivity of the plasma, for optimum RCS.

RETRACTED: Adaptive attitude control and the modeling of hypersonic vehicles with mismatched disturbances

Hypersonic vehicles often use the aerodynamic configuration and light materials such as lifting body and waverider, which leads to the unmatched uncertain control problems caused by strong coupling characteristics and interference during reentry. To solve these problems, firstly, this paper analyzes the key factors and uncertainties that affect the attitude motion of hypersonic vehicle. Secondly, it studies the modeling and verification of rigid body and elastic body of hypersonic vehicle, establishes the error model with disturbance observation compensation, and proposes a new attitude control scheme of hypersonic vehicle, which realizes the stable tracking of attitude angle and improves the uncertainty of key parameters of the system. The simulation results show that the performance index meets the requirements and has good robust performance in the presence of unknown disturbance.

Adaptive parameter estimation control of nonminimum phase hypersonic flight vehicle

In this study, considering the longitudinal dynamic model of a nonminimum phase hypersonic flight vehicle, output-redefinition-based adaptive parameter estimation control is proposed. Output redefinition is employed to transform unstable internal dynamics to asymptotically stable internal dynamics. Based on the coordinate transformation of the redefined internal dynamics, the pitch angle command is derived and used as the reference command of the input-output subsystem. For the redefined attitude subsystem and the velocity subsystem, the unknown aerodynamic functions are decomposed into the known state vector and the unknown aerodynamic parameter vector, that is the linear parametric form. The adaptive updating laws are constructed to estimate the aerodynamic parameter vectors, and then the dynamic inversion control is designed for the velocity subsystem and the backstepping control is designed for the input-output subsystem. The system stability is analyzed via the Lyapunov stability theorem while simulation studies are conducted to illustrate the effectiveness of the proposed method.

Guardian Map Approach to Feasible Range of Static Stability Margin of Hypersonic Flight Vehicles with Input Saturation

Static stability margin is a critical parameter in flight control design. The feasible range of it must cover the uncertainty through the flight. To reasonably identify the feasible range of static stability margin in advance, an approach based on guardian maps is proposed for flight control of hypersonic flight vehicles with input saturation. First, the model of hypersonic flight vehicle (HFV) is established as a parametric plant. Then, flying quality requirements for the closed-loop system are formulated as inequality constraints using guardian maps. Moreover, by using linear matrix inequality, the saturation of elevators is taken into account in the integrated control of attitude control. The prescribed minimum of static stability margin that ensures the flying quality of hypersonic flight vehicles with input saturation is obtained. Furthermore, from the prospective of integrated control, it is shown that the feasible range of static stability margin can be enlarged by changing aerodynamic characteristics. The effectiveness of the proposed approach is validated by numerical simulation.

Fractional-order proportional-integral-derivative linear active disturbance rejection control design and parameter optimization for hypersonic vehicles with actuator faults

The hypersonic vehicle model is characterized by strong coupling, nonlinearity, and acute changes of aerodynamic parameters, which are challenging for control system design. This study investigates a novel compound control scheme that combines the advantages of the Fractional-Order Proportional-Integral-Derivative (FOPID) controller and Linear Active Disturbance Rejection Control (LADRC) for reentry flight control of hypersonic vehicles with actuator faults. First, given that the controller has adjustable parameters, the frequency-domain analysis-method-based parameter tuning strategy is utilized for the FOPID controller and LADRC method (FOLADRC). Then, the influences of the actuator model on the anti-disturbance capability and parameter tuning of the FOLADRC-based closed-loop control system are analyzed. Finally, the simulation results indicate that the proposed FOLADRC approach has satisfactory performance in terms of rapidity, accuracy, and robustness under the normal operating condition and actuator fault condition.

Parameter Adaptive Terminal Sliding Mode Control of Flexible Coupling Air-Breathing Hypersonic Vehicle

The highly nonlinear and coupling characteristics of a flexible air-breathing hypersonic vehicle create great challenges to its flight control design. A unique parameter adaptive nonsingular terminal sliding mode method is proposed for longitudinal control law design of a flexible coupling air-breathing hypersonic vehicle. This method uses adaptive reaching law gain instead of the additional adaptive compensation term to handle the uncertainty to improve robustness. The stability of the close loop system is proved via a Lyapunov way. The longitudinal tracking control law for velocity and angle of attack is designed based on a rigid dynamic model of a flexible air-breathing hypersonic vehicle. A strong coupling model of the same vehicle, considering aerodynamic-scramjet engine-flight dynamic-elastic couplings, is established as the verification platform of the designed control law. The remarkable differences of flight dynamic characteristics between this strong coupling model and the rigid body model can be seen, which mean the controller needs to endure very great uncertainty, unmodeled dynamics, and other types of internal disturbance. Simulation results based on the coupling model demonstrate that the designed control law has good performance and acceptable robustness.

An Exponential-Based DGTD Method for Modeling 3-D Plasma-Surrounded Hypersonic Vehicles

Plasma surrounding a hypersonic vehicle can lead to the absorption of incoming radar radiation or the interruption of communication. Therefore, the development of hypersonic vehicle relies on a clear understanding of the strong interaction between the surrounding plasma and the incident electromagnetic wave. However, because of the presence of complex geometrical features and heterogeneous media, these applications are often multiscale. The modeling of such applications in 3-D is extremely challenging for traditional numerical methods. In this work, an efficient discontinuous Galerkin time-domain (DGTD) method for the 3-D modeling of plasma-surrounded hypersonic vehicles is presented. To overcome the grid-induced stiffness problem arising from the modeling of such multiscale applications with dispersive media, and to improve the modeling efficiency, a high-order exponential-based time integration for the time-domain Maxwell’s equations discretized by DG schemes with a general flux formulation is proposed. This time integration has excellent stability properties in the locally refined part of the mesh and hence enables the usage of larger time steps compared with the explicit time marching scheme. Additionally, the exponential-based time integration is developed to adapt an anisotropic perfectly matched layer for the modeling of open-domain problems. Finally, numerical experiments are presented to investigate the accuracy and convergence properties and to demonstrate the well-modeling capability of the proposed method.

Decoupling Attitude Control of a Hypersonic Glide Vehicle Based on a Nonlinear Extended State Observer

Aiming at solving the attitude control problem of a hypersonic glide vehicle, this paper proposes a decoupling control method based on a nonlinear extended state observer (NESO). According to the decentralized robust control theory of Tornambè, the coupling terms and the uncertainties are regarded as generalized uncertainties, and the NESO-based estimation and compensation signals are added to the closed-loop control law. The theoretical deduction proves that the proposed method can ensure that the tracking error of the closed-loop system is uniformly bounded. The simulation is carried out on the hypersonic glide vehicle model and compared with the traditional subchannel feedback control method. The simulation results show that the designed decoupling control method has superior control performances, and the influence of channel-coupling and uncertainty is compensated to a great extent.