Improved finite-time-convergence-differentiator-based robust back-stepping control of an air-breathing hypersonic vehicle

A robust back-stepping controller based on improved finite-time-convergent differentiator is designed to solve the problem of parameters uncertainty in flexible model of air-breathing hypersonic vehicle (AHV). Virtual and actual control laws are designed based on back-stepping and dynamic inversion design procedure respectively. Improved finite-time-convergent differentiator (FD) is introduced to obtain the derivatives of virtual control laws, which avoids the explosion of differentiation terms in the traditional back-stepping control. A nonlinear disturbance observer (NDO), which is based on finite-time-convergent differentiator, is designed to estimate and compensate the model uncertainties, which enhances the controller's robustness. Simulation results demonstrate the effectiveness of this controller in tracking velocity and altitude commands in the presence of model uncertainty and flexible dynamics.