Global and robust attitude control of a launch vehicle in exoatmospheric flight

The goal of this research is to design global attitude control systems for launch vehicles in exoatmospheric flight. An attitude control system is global when it guarantees the vehicle converges to the desired attitude regardless of its initial condition. Global controllers are important since they allow to perform large angle maneuvers using simpler algorithms with respect to several local controllers patched together. It is also required that the designed autopilots are robust, which means global convergence must be achieved despite uncertainties in the parameters of the vehicle. Two designs are carried out. In the first one possible delays introduced by the actuator are neglected. The first design is performed by using a Lyapunov approach, and the obtained autopilot is a standard proportional- derivative controller. In the second one, the effects of the actuator are considered. Then, the design is based on a robust backstepping approach which leads to a memory-less nonlinear feedback of attitude, attitude-rate, and engine's deflection angle. Both autopilots are validated in a case study.