Conditional disturbance negation based active disturbance rejection control for hypersonic vehicles

This paper presents a conditional disturbance negation (CDN) based active disturbance rejection control (ADRC) scheme for the velocity and altitude tracking control of flexible air-breathing hypersonic vehicles (FAHVs) in the presence of various uncertainties and disturbances. A pioneering CDN module is proposed to selectively compensate the total disturbances according to the characteristics of the total disturbances and the FAHV dynamics, which is aimed at canceling some detrimental disturbances while profiting from other beneficial disturbances. Firstly, model-based extended state observers are applied to estimate the total disturbances in FAHVs in an efficient way. Based on the Lyapunov theory and the estimated disturbances, a novel disturbance characterization indicator (DCI) is then designed to show whether the total disturbance harms or benefits the tracking performance in engineering practice. Then, DCI is utilized to construct the CDN module. In consequence, the CDN based FAHV tracking control is implemented in an ADRC framework, yielding the CDN based ADRC scheme. The stability analysis is conducted to show the convergence of the closed-loop system. Finally, the effectiveness and superiority of the proposed control scheme are validated by some representative simulations in various flight conditions.