The Application Of Quasi-continuous High Order Sliding Mode In The Controller Design Of Hypersonic Vehicles

Hypersonic vehicle techniques are the combination of Aeronautics and Astronauticsand related to multidisciplinary integration. Hypersonic Flight control is among the mostcrucial technologies. Hypersonic vehicle model has the character of highly nonlinearity,strong coupling, and strong uncertainty. And this is a difficult problem in control design.Dealing with nonlinear hypersonic vehicle model, accurate linearization method isutilized to linearize the input/output relation of the model. Then based on the linearizedmodel, Quasi-continuous high order sliding mode method is used to design the controller,simulation results demonstrate the controller has the ability to stabilize the vehicle andtrack the reference command. In order to construct the controller, exact robustdifferentiator is designed to obtain high order derivatives of state variables. Through thesimulation of third and fourth order differentiator, the relationship between differentiator’sorder and convergence time is discussed in detail. Finally, by simulation analysis ofparameter uncertainty of the model, the robustness of Quasi-continuous high order slidingmode controller is verified. While the performance of the controller still needed to bemade clear quantitatively, three control methods are introduced for comparation includingstandard sliding mode, optimum control and backstepping. Simulation results demonstratethat the Quasi-continuous high order sliding mode method takes less time to converge andthe accuracy of the method is one order of magnitude higher than others. Meanwhile,another advantage of Quasi-continuous high order sliding mode is discovered. Thismethod is applicable for large velocity and altitude variation, which is helpful in reducingthe number of controllers when designing a whole flight envelope control system.Above all, the application of Quasi-continuous high order sling mode in hypersonicvehicle is deeply studied. In the controller design process, the parameter selection and thecontroller construction method are also detailed discussed. Through the comparation, theconvergence property is studied and useful results are obtained.