Simple Adaptive Bank-Reversal Control for Non-linear Winged Re-entry Vehicles
Simple adaptive control can be applied to any non-linear system, provided it is almost strictly passive. A necessary condition is that each control channel is single-input single-output. Winged re-entry vehicles, where reaction and aerodynamic control are combined, do not fulfill that condition. In particular, gliding vehicles at large angle of attack, where the rudders are partially shielded by the fuselage, need yaw thrusters to support the weak rudder control. Instead of commanding the actuators directly, a required moment per axis is commanded, and the actual actuator allocation is done outside the controller. Not only does this make the closed-loop system almost strictly passive, but also the controller design is simplified. The current paper addresses such a control-system design, and applies it to two bank reversals, one at low and one at high dynamic pressure. Despite large perturbations and actuator saturation, the controller remains stable and can be considered robust.