EHA Cascade Sliding Mode Position Control Based on System Virtual Decomposition

Compared with valve controlled electro-hydraulic servo actuators (SHA), EHA eliminates servo valves and has advantages such as high efficiency and strong pollution resistance. Therefore, it has been applied in the main flight control system of aircraft. But Parameter uncertainties, system modeling errors, and external disturbances compromise the control precision and stability of Electro-Hydrostatic Actuators (EHA), directly impacting aircraft flight safety. To mitigate these challenges, a cascade sliding mode control strategy, based on system virtual decomposition, is proposed. EHA is decomposed into mechanical, hydraulic, and motor subsystems. Sliding mode control is employed to attenuate mechanical disturbances, while non-singular terminal sliding mode control is utilized to mitigate hydraulic flow disturbances. The motor subsystem is controlled using the widely adopted Field Oriented Control (FOC) strategy. Stability analysis is conducted via Lyapunov stability analysis. Simulation results demonstrate superior disturbance rejection capa-bilities compared to traditional PID control.