Observer-based fixed-time continuous nonsingular terminal sliding mode control of quadrotor aircraft under uncertainties and disturbances for robust trajectory tracking: Theory and experiment

This paper solves an accurate fixed-time attitude and position control problems of a quadrotor UAV system. The aircraft system is subject to nonlinearities, parameter uncertainties, unmodeled dynamics, external time-varying disturbances. To deal with the under-actuation problem quadrotor’s hierarchical structure inner–outer loop framework adopted for flight design. Robust nonlinear strategies are innovatively proposed based on new continuous nonsingular terminal sliding mode (CNTSMC) scheme. A full-order homogeneous surface designed states in such way that motion stable independently system’s initial condition. Hence, this contributes enhancing robustness. disturbance observer-based (DOBC) approach developed stabilize inner rotational subsystem (attitude-loop). compounded integrates finite-time observer (FTO) CNTSMC FTO incorporated into cope strong perturbations. An output-feedback outer translational (position-loop) ensure velocity-free control. In context, scheme combined extended state (FXESO) achieve active rejection (ADRC) by estimating canceling lumped Therefore, within including robust scheme, DOBC, ADRC strategies, trajectory tracking can be achieved despite uncertainties Stability analysis closed-loop rigorously investigated using Lyapunov theorem, bi-limit theory, notion input-to-state stability (ISS). Extensive experimental tests under influence various disturbances conducted corroborate theoretical findings. end, effective model-based design (MBD) established implement algorithms real autopilot hardware. Furthermore, processor-in-the-loop (PIL) experiments also carried out MBD framework. comparative study made involving our other strategies. Overall, obtained results show synthesized yields performance improvement regarding featuring fast transient, robustness, high steady-state precision. Besides, chattering effect regular linear (LSMC) significantly alleviated. Moreover, unlike conventional TSMC, input shows no singularity.