Enhanced composite nonlinear extended state observer based on trajectory linearization control in presence of external and internal disturbance

This paper investigates a novel compound control scheme combined with the advantages of trajectory linearization control (TLC) and alternative enhanced composite nonlinear extended state observer (ECNESO) in presence external and internal disturbance. First, an improved generalized tracking differentiator (IGTD) is applied to realize differentiation and filtering for the reference command. Second, ECNESO are constructed to estimate the uncertainties acting on the LTV. In addition, combining the novel observer with TLC strategy, a method is developed to force the controlled output to track the reference signal, rather than just stabilizing it around zero. Moreover, for the first time, this paper gives a rigorous proof of enhanced extended state observer (EESO) for nonlinear systems. The proposed TLC- ECNESO strategy is guaranteed the robustness of closed-loop system in the presence of parametric uncertainties and internal and external disturbances, in addition, the simplicity of the proposed strategy can meet the real-time computational requirement in practical air vehicle control systems. Stability analysis verifies that all signals in the closed-loop system are uniformly ultimately bounded. Finally, numerical simulation studies demonstrate the feasibility and efficacy of the proposed method.