Adaptive Backstepping Control Based Autopilot Design for Reentry Vehicle

A robust controller design methodology for high speed reentry vehicles (HSRV) is presented in this paper. The design methodology is based on a nonlinear backstepping technique. High speed reentry vehicles often contain signiflcant nonlinearities in the dynamics equation of motion which are partially caused by the high velocities and ∞ight path trajectories. These two factors tend to produce signiflcant aerodynamic forces and moments on the vehicle. The nonlinear backstepping control technique provides an alternative to methods such as piecewise linearization-based gain scheduling and feedback linearization. Backstepping approaches utilize Lyapunov theory to guarantee stability of the closed system and the methods are inherently recursive. Nonlinear optimization is also used to guarantee the accuracy of the mapping between the actuators and applied moments and an adaptive term is included to compensate for the moment bias. The proposed design procedure turns out to be simpler than designs based on alternative methods and the design appears relatively easy to implement.