Robust tracking control for the hypersonic flight vehicle via backstepping method

The problem of output tracking control is addressed for the longitudinal dynamics of a generic hypersonic flight vehicle. For the altitude subsystem and velocity subsystem, the dynamics is transformed into block-triangular form where the backstepping scheme is used. This problem is challenging due to the nonlinear uncertain complex interactions between the altitude and velocity subsystems. A new design approach of robust controller is proposed by combining standard backstepping with signal compensation method. It is shown that semiglobal robust stability and semiglobal robust practical tracking property of the closed-loop system can be ensured and the tracking error can be made as small as desired.