Disturbance observer–based control of flexible hypersonic flight vehicle

Abstract

In this article, the disturbance observer-based control is designed for a flexible hypersonic flight vehicle with the external disturbance. The aircraft structure is easy to cause elastic vibration, thus leading to serious change in structural configuration or even disintegration. Therefore, the impact of elasticity modal for altitude subsystem is described as a system disturbance, and then, the equivalent model is established. On this basis, considering the model structure and composition of nonlinear systems, the disturbance observer is used to eliminate the information of the disturbance. Finally, the simulation results make an offer to show that the disturbance observer-based control can provide a good tracking performance.

Robust tracking control for two classes of variable stiffness actuators based on linear extended state observer with estimation error compensation

“…In this section, the stability of the closed-loop system under the proposed controller is analyzed. Invoking equations (28) to (46) and Lemma 1, the related calculations shown in equations (47) to (56) can be obtained…”

“…Finally, the simulation results show the effectiveness, robustness, and good adaptability of the designed controller. The proposed design idea of reducing the tracking error can be extended to the tracking control of other types of systems [26][27][28][29][30][31][32][33][34][35][36][37][38][39][40] to improve the tracking accuracy and disturbance rejection performance of the controller.…”

“…The first-order time derivative of e q1 is given by equation (28) where d q1 represents the estimation error…”

“…In the current studies on robust tracking control, DOB [24][25][26][27][28] and extended state observer (ESO) are two popular methods to effectively deal with the uncertainties and the disturbances in the systems. Generally, the ESOs can be classified into the linear extended state observers (LESOs) and the nonlinear extended state observers (NESOs).…”

“…[29][30][31][32][33][34][35][36][37][38][39] For the antagonistic VSAs based on equivalent nonlinear torsion springs (ENTSs) in the presence of parametric uncertainties, unknown friction torques, unknown external disturbance, and input saturation constraints, a combination of the LESO, the sliding mode control (SMC), and the adaptive input saturation compensation (ISC) is designed to achieve the simultaneous position and stiffness tracking control of the VSAs. 40 However, in the above studies, 21,[26][27][28][29][30][31][32][33][34][35][36][37][38][39][40] the estimation errors were not considered explicitly in the DOB-based control or the LESO-based control.…”