Int. J. Vehicle Design, Vol. 68, Nos. 1/2/3, 2015 119 Copyright © 2015 Inderscience Enterprises Ltd. Load-dependent LPV/H 2 output-feedback control of semi-active suspension systems equipped with MR damper Jaffar Seyyed Esmaeili* and Ahmad Akbari Department of Electrical Engineering, Sahand University of Technology, P.O. Box: 51335/1996, Tabriz, Iran Email: j_esmaeili@sut.ac.ir Email: a.akbari@sut.ac.ir *Corresponding author Hamid Reza Karimi Faculty of Engineering and Science, Department of Engineering, University of Agder, N-4898 Grimstad, Norway Email: hamid.r.karimi@uia.no Abstract: This paper is concerned with the problem of load-dependent H 2 control for vehicle semi-active suspension. A quarter-car model equipped with a magnetorheological (MR)-damper, which captures essential features of a real car suspension, is considered in this study. H 2 -norm measures the root-mean-square (RMS) value of output to white noise input. Considering the fact that road roughness is often modelled as white noise, H 2 -norm is used to quantify control objectives of ride comfort and safety as well as suspension deflection and control effort. To guarantee system performance against parameter variations, a linear matrix inequality (LMI)-based design framework has been utilised and a linear parameter-varying (LPV) controller is synthesised. The design procedure of the semi-active suspension requires the inverse dynamics of MR damper, which is obtained through a locally linear neuro-fuzzy (LLNF) network. To illustrate the effectiveness of the proposed approach, the system outputs for both impulse and real road inputs are compared with H ∞ controller in terms of performances. Keywords: semi-active suspension; LPV/H 2 control; H ∞ control; LMI; MR damper. Reference to this paper should be made as follows: Esmaeili, J.S., Akbari, A. and Karimi, H.R. (2015) ‘Load-dependent LPV/H 2 output-feedback control of semi-active suspension systems equipped with MR damper’, Int. J. Vehicle Design, Vol. 68, Nos. 1/2/3, pp.119–140. Biographical notes: Jaffar Seyyed Esmaeili received his BSc and MSc in Control Systems Engineering from the Sahand University of Technology, Tabriz, Iran, in 2009 and 2011, respectively. His research interests include