Generic Air-breathing Hypersonic Vehicle Research Articles

A Novel Robust Flight Controller Design for an Air-Breathing Hypersonic Vehicle

A novel robust flight control design method is proposed for a generic air-breathing hypersonic vehicle based on a state-dependent Riccati equation technique and a nonlinear disturbance observer. The highly nonlinear dynamics of the hypersonic vehicle are firstly brought to a linear structure having a state-dependent coefficient form. And then a state-dependent Riccati equation is solved at each sampling moment to obtain a nonlinear feedback optimal control law. In order to enhance robustness of the closed-loop system, a nonlinear disturbance observer is introduced to estimate the uncertainty caused by parametric variations and external disturbances. The resulting composite controller achieves not only promising robustness and disturbance rejection performance but also flexible adjustment in the response time. Compared to a Kriging controller, the proposed controller has great advantages in the system response time and robustness. The feasibility of the proposed method is validated by simulation results.

Disturbance-observer-based fixed-time second-order sliding mode control of an air-breathing hypersonic vehicle with actuator faults

This paper presents a disturbance-observer-based fixed-time second-order sliding mode approach for fault-tolerant control of an air-breathing hypersonic vehicle, where both partial loss of effectiveness faults and bias faults in actuators are considered. Firstly, a fixed-time second-order sliding mode control law is designed to guarantee the reaching time, independent of initial conditions. Then, by using a robust uniformly convergent differentiator technique, a fixed-time convergent disturbance observer is established to quickly estimate the lumped uncertainty, which consists of actuator faults and system uncertainties. Therefore, any information of actuator faults is not required by this design. Finally, simulation results of a generic air-breathing hypersonic vehicle are presented to demonstrate the effectiveness of the proposed controller.

Flight Dynamic Characteristic Analysis of a Generic Airbreathing Hypersonic Vehicle

Because of the high speed, strong coupling between aerodynamics and propulsion system, complex environmental conditions and new propulsion system, the airbreathing hypersonic vehicles have a complex dynamics characteristic. This paper use the generic hypersonic vehicle model (CSULA-GHV) to research this issue. The nonlinear longitudinal equations of motion are linearized based on the assumption of little perturbation. Analyze the dynamic characteristic on a feature point selected. The results show that, the stability of this model is poor. It has to design an efficient controller to adjust the poor stability.

Nonsingular direct neural control of air-breathing hypersonic vehicle via back-stepping

This paper investigates the design of nonsingular direct neural control systems for the longitudinal dynamics of a generic air-breathing hypersonic vehicle (AHV). The control objective is to steer the velocity and altitude to track the given commands in the presence of unmatched disturbances. For the velocity subsystem, a neural network (NN) is employed to approximate the developed control law directly where a direct neural controller is designed. For the altitude subsystem that is transformed into strict feedback form, two NNs are used to estimate the virtual and actual control laws derived from back-stepping design. Hence the problem of possible control singularity and “explosion of terms” are avoided. More specially, a nonlinear tracking differentiator is introduced to reconstruct the flight-path angle and angle of attack that are difficult and costly to measure in practice. Numerical simulations are presented to verify the feasibility of the proposed control approach.

Composite predictive flight control for airbreathing hypersonic vehicles

The robust optimised tracking control problem for a generic airbreathing hypersonic vehicle (AHV) subject to nonvanishing mismatched disturbances/uncertainties is investigated in this paper. A baseline nonlinear model predictive control (MPC) method is firstly introduced for optimised tracking control of the nominal dynamics. A nonlinear-disturbance-observer-based control law is then developed for robustness enhancement in the presence of both external disturbances and uncertainties. Compared with the existing robust tracking control methods for AHVs, the proposed composite nonlinear MPC method obtains not only promising robustness and disturbance rejection performance but also optimised nominal tracking control performance. The merits of the proposed method are validated by implementing simulation studies on the AHV system.

Use of Energy-State Analysis on a Generic Air-Breathing Hypersonic Vehicle

Apossiblenext-generation launch vehiclemaybea fullyreusable,single-stage-to-orbitaerospacecraft.Thisclass of hypersonic vehicle includes highly integrated airframe and propulsion systems; hence fuel-optimal trajectories are of special interest. Also, because these vehicles are neither conventional aircraft nor rockets, the appropriate approach for trajectory analysis during preliminary design, for example, is of interest. Addressed here is whether the energy-state method is justie ed for the determination of such trajectories for scramjet-powered, hypersonic vehicles. The focus is on the scramjet-powered phase of the mission. The energy-state approach is known to be justie ed when the system dynamics exhibit multi-time-scale behavior, and such behavior is shown to exist for the vehicle and mission phase under investigation here. Furthermore, solutions obtained via the energy-state assumption are compared with a full dynamic solution obtained using a nonlinear programming routine. It is shown that the results from the two methods are in reasonably good agreement. On the basis of these results, the energy-state method would appear justie ed for the class of vehicle in question, at least for obtaining rapid performance estimates, as well as gaining insight into the basic performance issues.