Barrier Lyapunov Function based Sliding Mode Control for BWB Aircraft with Mismatched Disturbances and Output Constraints

This paper presents a barrier Lyapunov function based nonsingular fast terminal sliding mode control with fixed-time non-recursive disturbance observer for the blended-wing-body (BWB) aircraft in the presence of mismatched disturbances and output constraints. The fixed-time non-recursive disturbance observer based nonsingular fast terminal sliding mode control is proposed for matched and mismatched disturbances attenuation. Furthermore, in order to pursue high-precision attitude tracking regarded as output tracking errors constraints before disturbance observer tracking errors converge to a small prescribed range, the barrier Lyapunov function is designed to constrain the sliding mode variables before states reach the sliding mode surface. Consequently outputs tracking errors constraints can be satisfied by the sliding variables constraints. More importantly, barrier Lyapunov function based terminal sliding mode controller ensures the finite-time convergence. Finally, the numerical simulations demonstrate the chattering attenuation and high-precision attitude tracking of the BWB aircraft in the presence of mismatched disturbances and output constraints.