Extended disturbance observer based robust sliding mode control for active suspension system

Abstract

In this paper, the approach of reduced-order extended state observer (RO-ESO) proposed by Zuo and Nayfeh (J Sound Vib 265(2):459–465, 2003) for estimation of un-modeled dynamics and disturbances in the antilock braking system is extended to the half car active suspension system (HCASs). Reduced-order ESO is used to estimate the lumped parametric uncertainties, un-modeled dynamics, and external disturbances affecting the performance of HCASs. Here, the estimation accuracy is further improved by the modification of RO-ESO. Modified and extended disturbance observer (E-DO) is proposed to estimate these lumped disturbances and their derivatives, thus reducing disturbance estimation error. A sliding mode control (SMC) based controller is designed to stabilize the vehicle body’s heave and pitch motion using an active suspension system, resulting in ride comfort improvement with guaranteed suspension space constraint and road holding. The proposed E-DO-based SMC (E-DO-SMC) controller’s effectiveness and robustness is analyzed by MATLAB simulations conducted on two different road excitations. The results obtained are compared with RO-ESO based SMC (RO-ESO-SMC) and passive suspension system.