Design and Experimental Validation of a Robust Attitude Controller for a 3-DOF Hover System Under Network Constraint

This paper proposes a fast and reliable control strategy for a three-degree-of-freedom (3-DOF) Hover system subject to external disturbances and communication constraints. The objective is to achieve accurate tracking of time-varying reference trajectories while ensuring rapid convergence and minimizing unnecessary feedback transmissions. To this end, an event-triggered variable-exponent nonsingular terminal sliding mode controller (ET-VE-NSTSMC) is developed. The proposed controller guarantees fixed-time (FxT) stability of the relative dynamics, ensuring that tracking errors converge to zero within a predefined bound independent of the initial conditions. This approach departs from conventional fixed-time schemes by using a state-dependent variable exponent that adjusts based on how far the system is from its equilibrium point. Thus, the controller achieves a faster transient response while minimizing control effort. Moreover, an event-triggered mechanism is adopted to respect the bandwidth constraint, so the state feedback signal is updated only when it is needed. Thus, it saves communication resources without sacrificing tracking performance. The stability analysis using Lyapunov theory guarantees FxT stability of the surface and relative errors. The proposed strategy was then validated through hardware results on a Quanser 3-DOF Hover platform. The experimental results show that the ET-VE-NSTSMC strategy outperforms existing techniques, offering faster convergence, greater robustness, and improved communication efficiency.