Serialized isolator, absorber, and actuator based active suspension for suppressing high-frequency vibration via extended sliding mode observer based extended optimal sliding mode controller

To effectively suppress the body’s high-frequency vibration and reduce the enormous demanded control force of the electro-hydraulic actuator, a serialized isolator, absorber, and actuator (SIAA) based active suspension (AS) is firstly proposed. The proposed AS comprises a hydro-pneumatic spring, a suspension third mass, and an electro-hydraulic actuator in series from bottom to up. The former two components serve as the isolator and absorber, respectively. Besides revealing influences of the suspension third mass on the high-frequency vibration reduction effect and demanded control force, an extended sliding mode (ESM) observer based extended optimal sliding mode (EOSM) controller is developed. The ESM observer is responsible for the observed values related to the suspension comprehensive performance, and the EOSM controller takes charge of the true nominal optimal performance and robustness. Consequently, by using the SIAA based AS regulated by the specially designed nonlinear optimal robust controller, the peak of the sprung mass acceleration’s power spectral density in the high-frequency region and demanded control force’s root mean square are respectively reduced by 84.68% and 61.71% compared to the single-staged electro-hydraulic AS.