Nonstandard Backstepping Based Integral Sliding Mode Control of Hydraulically Actuated Active Suspension System

In this paper, the integral sliding mode control (ISMC) with non-standard backstepping is utilized for designing an automotive active suspension system hydraulic actuator. The main objective of this design is to make the suspension system's ride more comfortable while keeping the road holding and rattling space within safe bounded limits. The controller design consists of applying the ISMC to perform a virtual control force, that meets all suspension requirements, besides utilizing a hydraulic model by a non-standard backstepping control algorithm taking into consideration the uncertainty and nonlinearity of the hydraulic system. The main advantage of ISMC is to have a robust controller, such that the stability of the system appears from starting its states at the switching surface where system nonlinearity, parameter changes, and road disturbances are rejected by a discontinuous control term present strongly in the suspension dynamics. This work demonstrates the effectiveness of the present controller design through the simulation of a 2-DOF quarter car system equipped with a passive suspension. The results vividly showcase how the current design enhances the overall performance of the system.