Second order-dynamic surface based fixed time control for UAH under disturbances

System uncertainties and external disturbances pose significant risks to unmanned aerial helicopters (UAHs), potentially causing crashes and casualties. This paper proposes an adaptive fuzzy nonlinear disturbance observer (NDO)-based second-order dynamic surface control (DSC) strategy, integrating fixed-time stability theory. The fuzzy logic system (FLS) addresses system uncertainties, while compound disturbances (external disturbances and FLS approximation errors) are compensated by the fixed-time NDO. The DSC method mitigates differentiation explosion caused by power series growth. The convergence time depends only on design parameters, independent of initial conditions. Simulations verify the approach’s effectiveness.