An event-triggered nonsingular fixed-time sliding mode control (ET-NFxT-SMC) scheme is developed for trajectory tracking of quadrotor unmanned aerial vehicles (QUAVs). The proposed controller employs a state-dependent variable exponent (SDVE) framework to ensure fixed-time stability (FxTS). Unlike constant-exponent methods, it adapts the convergence rate dynamically to the system state, offering a simplified structure with reduced computational complexity. The proposed approach addresses altitude and attitude tracking problems in the presence of external disturbances and system uncertainties. An event-triggering mechanism is integrated to significantly reduce unnecessary control updates by up to 52% without compromising stability. Thus, computational load and signal transmission bandwidth are further reduced, while maintaining robust performance. The Lyapunov-based analysis ensures FxT convergence and confirms a positive lower bound on inter-event times, thus avoiding Zeno behavior. Simulation results demonstrate that the proposed controller achieves accurate and robust trajectory tracking with fewer control updates, leading to improved resource efficiency and practical implementation feasibility.
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