Research On Control Methods Of Air-breathing Hypersonic Vehicles

As a kind of nearspace aerocraft with high-speed and high-mobility,the air-breathing hypersonic vehicle(AHV)has been seriously taken into account by global powers.Although huge progress has been made on the research of AHVs in recent decades,the design of control system is still a big challenge.This paper focuses on the tracking control of the longitudinal dynamics of AHVs,which mainly has the following results.Firstly,the control-oriented mathematical models of AHVs are obtained.Based on the existing curve-fitted dynamic model of AHVs,both the feedback linearized model and the parameterized model are derived with proper assumptions.The parameterized model contains the block-feedback form and the strict-state-feedback form,which can be directly utilized in the back-stepping design.Secondly,the active disturbance rejection(ADR)control of AHVs is considered.A new finite-time tracking controller with ADR ability is proposed for AHVs based on terminal sliding mode theory.To obtain the relevant information of the mismatched disturbances,a finite-time disturbance observer is introduced.Moreover,a novel integral sliding surface is constructed and the relevant reaching law is designed with the utilization of the states in the observer,which can remove the effects of the mismatched disturbances from outputs.In spite of ADR ability,the proposed controller also regulates the tracking errors of velocity and altitude to zero in finite time,in which case the tracking performance is guaranteed.Thirdly,the problem of uncertain parameters is solved.Compared with the existing adaptive control strategies that focus on constant uncertain parameters,this paper further considers the case where time-varying parameters exist in the AHV model.By estimating the bounds of uncertain parameters or parameter vectors,the time-varying model parameters are accommodated,as well as the expressions of adaptive laws are largely simplified.Fourthly,the anti-windup control of AHVs is implemented.Within the frame of terminal sliding control or adaptive control,proper auxiliary systems are constructed to analysis the effects of the saturated actuators on the dynamics of AHVs.By introducing the states of auxiliary systems into design,the resulting controller has a good anti-windup ability.In addition,this paper also considers the dead-zone nonlinearity in the actuator with the help of adaptive dynamic inverse.Fifthly,the state-constrained control of AHVs is considered.In the literature,there is little research involving state constraints in the control of AHVs.This paper deals with the magnitude constraints on flight-path angle,pitch angle and pitch angle rate,as well as the constraints on angle-of-attack required by the scramjet.By introducing barrier Lyapunov functions in the adaptive design,these prescribed state constraints are guaranteed,which makes the designed controller more acceptable in engineering.In summary,this paper systematically presents tracking controllers for AHVs subject to mismatched disturbances,uncertain parameters,actuator nonlinearities and state constraints,which can be regarded as a good complement to the existing research,as well as a technical reserve for the practical realization of hypersonic flight control system.