Time-varying bandwidth extended state observer-based trajectory tracking control for unmanned helicopters with disturbances

This paper investigates the trajectory tracking problems of a disturbed unmanned helicopter. A time-varying bandwidth extended state observer (TBESO) is developed to estimate lumped disturbances, mitigating the performance limitations of observers due to fixed bandwidth and effectively reducing the initial peaking phenomenon while ensuring strict stability proof. Based on the disturbance information estimated by TBESO, an adaptive super twisting algorithm sliding mode controller (ASTASMC) and an adaptive feedback controller (AFC) are proposed for position and attitude subsystems, respectively. The designed approach reduces dependency on model information, resulting in a more concise control structure. In addition, the introduction of adaptive method eliminates the effects of static parameter deviations, reduces parameter sensitivity and enhances control accuracy. The stability of control system is rigorously proven using Lyapunov theory. Finally, numerical simulations comparing the designed scheme with linear active disturbance rejection control (LADRC) and TBESO-based block backstepping control (BBSC) demonstrate its superiority and effectiveness.