Constrained adaptive tracking and command shaped vibration control of flexible hypersonic vehicles

This study presents a new approach, which integrates the input shaping technique and the constrained adaptive backstepping control method, for constrained adaptive tracking and elastic vibration control of flexible hypersonic vehicles. Specifically, the input shaper as a feedforward part is implemented outside the feedback loop, which can achieve vibration suppression for flexible dynamics; whereas for the feedback loop, the vehicle model is decomposed into functional subsystems, and the decentralised approach is used. Then, by introducing the command filter and the auxiliary system, constrained adaptive control law is formulated to make the closed-loop system follow the shaped reference trajectory and attenuate the elastic vibration in the presence of parameter uncertainties, external disturbances and input saturation constraints. An attractive feature of this proposed control algorithm is that all signals of closed-loop system are uniformly ultimately bounded and the tracking error converges to a residual set which can be made sufficiently small by properly designing control parameters. Moreover, by applying the shaped commands, flexible dynamics with less elastic deformation and vibration can be achieved without destroying the closed-loop performance. Simulation results are provided to verify the effectiveness of the proposed control method.