Research on disturbance in nearspacevehicle longitudinal trajectory system

Considering the severe changes of aero-dynamic parameters and susceptibility on the external disturbances of nearspace vehicle (NSV), a backstepping control strategy with robust adaptive dynamic surface is proposed in this paper for the disturbance problem in the NSV longitudinal trajectory system during the hypersonic process. Firstly, the complex nonlinear longitudinal dynamic model is transformed into nonlinear affine model by using the input-output feedback linearization method. Meanwhile, the “computer explosion“ in the computation procedures for derivatives is avoided with the estimation of the virtual control law in one-order low pass filter. Then,the robustness item in the virtual controller ,which combined with approximation capability of neural network, is used to eliminate the parameter uncertainties and external disturbances in NSV. The simulation results show the improved robustness in this method with reduced complexity.