Method For Modeling And Trajectory Tracking Control Of A Hypersonic Vehicle

Hypersonic vehicle(HSV) is a kind of special craft different from generalaeronautical and space vehicles with the prominent feature of high speed. Thedeveloping hypersonic technology related with HSV must have a far-reaching influenceon the military area and civil and commercial fields. HSV flies in a severe environment,and its structure is designed with an elongated shape, the analyses show that the openingloop dynamic characteristic is not stable. Its rigid body dynamics are coupled seriouslywith structural dynamics and have many unknown uncertainties.The general HSV model with flexible modal coordinates dynamics is deriveddetailedly. Then the model is simplified with the flexible modal coordinates dynamicsand linearized in a set of given equilibrium points, then the dissertation got thetransmission zeros and system poles of the opening loop linearized system and analysedthe dynamic characteristics of the vehicle.The rigid body model is handled with input-output linearization and then turnedinto a linear model. Based on the linear model, then two dynamic inversion controllersare designed with a pole assignment method and a LQR optimal method, respectively.Simulations under the nominal model without disturbance show the controllers cantrack the desired signals well. Then the dissertation used sliding mode control(SMC),finite-time integral sliding mode control, second-order terminal sliding modecontrol(2TSMC) methods to handle the trajectory tracking control problem. Simulationsunder the nominal model without disturbance show that the finite-time integral slidingmode control method has certain robustness and the2TSMC has shorter settling timeand smaller tracking errors than the SMC.The dissertation designed a sliding mode disturbance observer(SMDO) to estimatethe uncertainties and disturbances, and then compensate for2TSMC. Simulations showthat2TSMC with SMDO has shorter settling time and smaller tracking errors.Considering the elastic vibration reducing problem based on the flexible HSVmodel, The dissertation only designed a SMC controller for the rigid body dynamicspart and a notch filter in the pitch rate feedback loop. The simulations show the notchfilter can reduce the elastic vibration in some degree. Then a sliding mode state observeris designed to estimate the unmeasurable states of angle of attack and track angle.