Nonlinear robust neuro-adaptive flight control for hypersonic vehicles with state constraints

This paper presents a new nonlinear robust neuro-adaptive state-constrained control formulation for effectively controlling a hypersonic flight vehicle in cruise. The proposed controller ensures that the vehicle velocity, attitude and angular body rates remain bounded within the prescribed limits. The asymptotic stability of the closed-loop system in presence of imposed state constraints is shown following barrier Lyapunov function based stability theory. A Sobolev norm-based adaptive control scheme is used along with the nominal controller to ensure the stability of the vehicle in the presence of model uncertainties (as high as 30%). The adaptive control formulation leads to quick learning with much lesser transients and is robust enough not to violate the imposed state-constraints. The effectiveness of the proposed nonlinear control design is illustrated by carrying out a large number of Monte-Carlo like randomized high fidelity six-degree-of-freedom (Six-DOF) simulation studies.