Cascaded Nonlinear Active Disturbance Rejection Control with Time Delay Compensation for Flight Environment Simulation Systems

The flight environment simulation system is used for development and testing of advanced aeroengines, where the crucial intake pressure subsystem provides properly conditioned air pressure for simulating the flight speed. The time delay existing in the large-scale hydraulic regulating valves of the system significantly degrades pressure control performance and may even cause oscillations, especially when multisource disturbances and sensor noises occur. To tackle this challenge, a cascaded nonlinear active disturbance rejection control scheme with time delay compensation (TDC-CNADRC) is proposed. In particular, an output prediction–based time delay compensation (TDC) strategy is designed, in which accurate and real-time differential signals obtained from a tracking differentiator are utilized to estimate the delayed output and compensate the time delay effect. Furthermore, an enhanced nonlinear extended state observer, which possesses a novel nonlinear state error gain function, is proposed to improve the estimation precision of the total disturbances. Experimental results demonstrated that the proposed TDC-CNADRC significantly suppresses valve position oscillations, ensuring smooth tracking with small overshoots. In addition, thrust transient experiments further verified that the intake pressure control performance is improved in terms of disturbance rejection capability and response speed.