Technology Of Robust And Adaptive Control Of A Hypersonic Vehicle

With a special manoeuvring airspace and extremely high speed,an air-breathing hypersonic vehicle has the advantages of strong survivability,good cost-effectiveness and quick response.Those advantages make an AHV strategically valuable and extensively applicable.Considering the huge value of an AHV,several countries with strong ability in the field of aerospace are quite interested in the research of it,and have had many research results.In order to occupy the high land in this field,we should pay more attention to develop the key and supporting techniques.As a produce of the fusion of aerotechnics and astronautical technology,there are great obstacles both in theoretical research and engineering practice,which makes it necessary to break through in many aspects.Aiming to secure the flight and complete different missions,the flight control system is a key stone for the AHV.With respect to common flight control,the control of an AHV has such difficulties: a higher demand of the control accuracy,more factors to consider and much higher complexity.In this thesis,in the frame of nonlinear control,these factors such as input delay,disturbance,saturation of input,model uncertainties and non-affine in control are considered.Under different considering and assumptions,the robust and adaptive control of an AHV is well studied.The contents of the thesis are mainly listed as below:Firstly,an AHV with a winged-cone configuration is described.Using the mechanics of rigid bodies,a group of equations with six-DOF and twelve states is derived.The aerodynamic model of it is given.At last,the open loop characters of the AHV's dynamic model are studied.Secondly,the attitude control of an AHV considering input delay is studied.When the signal transmission process and the dynamic of actuators is abstracted as an input delay term,and the wind interference and modeling error are treated as an exo-disturbance,the control problem of nonlinear systems with input delay and disturbance is produced.Based on the delay compensation theory,nonlinear disturbance observer and nonlinear damping controller,a new resolve framework for the nonlinear regulation with input delay is produced,and the controller design process is described giving stability conclusions.The attitude controller of an AHV is then derived using that framework,and simulation results are given which verifies the framework.Thirdly,the robust and adaptive control of a class of nonlinear systems with input saturation and exo-disturbance is studied,and it is applied on the AHV's attitude control.Two types of uncertainties are considered,and the controller for each type is designed.The first type assumes that the velocity of the uncertainty is bounded with an unknown boundary.With this type of uncertainty,the tracking control of an uncertain nonlinear system with input saturation is studied,and a DSC controller is given whose stabilization is assured by a given theorem.The other type assumes,from the view point of disturbance suppression,that the exo-system contains uncertainties with unknown boundaries.For this type of uncertainty,a robust and adaptive disturbance observer is presented,which develops the disturbance theory.A robust and adaptive controller is given using the robust disturbance observer and input saturation compensation.The practical stability both of the observer error system and the closed loop controlled system is proved and summarized as theorems.Simulation results are given for the AHV attitude system with each type of uncertainties,and the presented theory is verified.Fourthly,the robust and adaptive control of a class of nonlinear system with uncertainties in the control gain matrices is studied and applied on the attitude control of an AHV.For the uncertainties,two types of assumptions are made,and relative treatments are studied.The first type assumes that the control gain matrix is unknown but positive definite.With this type of uncertainties,a nonlinear tracking control problem is solved by a robust and adaptive control,and the closed loop system is assured practically stable by a given theorem.The other type assumes that the gain matrices are invertible and all the elements of the control gain matrices are unknown both in value and in sign,but their signs are all the same.With that type of uncertainties,the tracking control of a class of nonlinear systems with model uncertainties whose velocity boundary is unknown and parameter uncertainties is studied.A new Nussbaum function matrix based robust and adaptive control is presented to realize the tracking control.The stability of the closed loop system is proved and summarized as a theorem.The control method is then applied on the attitude control of an AHV.Simulation results are given and verified the presented theory.The affection of the designed adaptive laws to the steady response of an AHV is also analyzed.Fifthly: The trajectory tracking control of an AHV is studied.Based on the two-timescale character,the trajectory tracking control of an AHV is divided into two parts: the trajectory tracking loop and the attitude tracking loop.For the trajectory loop,making use of the structure characters,following the path of the dynamic inversion and taking advantage of the robust and adaptive control,a controller considering the non-affine in the control channel is presented in an explicit form.Based on analyzing the uncertainties and disturbances in an AHV's dynamic model,after making reasonable assumptions,the attitude control model of the AHV is gained with an applicable form.Using the attitude control design results in preceding chapters,the attitude controller here is easily constructed.Simulation results are given and verify an eclectic trajectory control strategy.Through simulation,the low aerodynamic efficiency of the actuators of the AHV at a very high altitude is presented.