Propellant-Sloshing Estimation and Suppression of Reusable Launch Vehicles Using Active Disturbance Rejection Control

The multi-source disturbances dominated by liquid propellant sloshing pose a critical challenge to the stability and safety of attitude control in reusable launch vehicles (RLVs). Therefore, this paper investigates the effects of propellant sloshing on RLV attitude control and the suppression method of liquid sloshing. To address disturbances such as propellant sloshing and wind interference, an extended state observer (ESO) is employed for real-time estimation of total disturbances, with the estimated extended state used for total disturbance compensation, and proportional-derivative control applied for attitude control. Finally, simulation results indicate a complex coupling relationship between propellant sloshing and RLV attitude control, which significantly affects attitude control stability. Active disturbance rejection control (ADRC) can effectively suppress liquid sloshing and enhance attitude control performance, demonstrating its strong capability on disturbance rejection and control performance.