1 Copyright © 2002 by ASME Proceedings of ESDA2002: 6th Biennial Conference on Engineering Systems Design and Analysis Istanbul, Turkey, July 8-11, 2002 ESDA2002/APM-093 USE OF COMPUTER AIDED METHODS FOR OPTIMISATION IN VEHICLE SUSPENSION DESIGN AND FOR DESIGNING ACTIVE SUSPENSIONS Ali Boyalı Uzel Makina A.Ş. Topçular Kışla Cad. No: 5 İstanbul, TR-34147 E-mail: aboyali@uzel.com.tr Serdar Öztürk Department of Mechanical Engineering İstanbul Technical University, Gümüşsuyu, Taksim, TR-80191,İstanbul, Turkey Fax:+90 212 2450795 E-mail: esozturk@yahoo.com Tevfik Yiğit Department of Mechanical Engineering İstanbul Technical University Gümüşsuyu, Taksim, TR- 80191,İstanbul, Turkey Fax: +90 212 2450795 E-mail: tevfikyigit@yahoo.com Bilin Aksun Güvenç Department of Mechanical Engineering İstanbul Technical University Gümüşsuyu, Taksim, TR- 80191,İstanbul, Turkey Fax: +90 212 2450795 E-mail: guvencb@itu.edu.tr Levent Güvenç Department of Mechanical Engineering İstanbul Technical University, Gümüşsuyu, Taksim, TR- 80191,İstanbul, Turkey Fax: +90 212 2450795, E-mail: guvencl@itu.edu.tr ABSTRACT The suspension is a very important subsystem of a vehicle as it affects both passenger ride comfort and the handling properties of the vehicle. This paper concentrates on two important aspects of suspension system design. One is the fine tuning of a passive suspension system design through an optimisation study using a virtual suspension system model. The second is the design and testing of an active suspension controller. Both problems are treated here in a computer aided setting using a highly realistic suspension system and a full vehicle model, respectively. INTRODUCTION The main reason for the existence of a suspension system like that shown in Figure 1 can be thought of as isolating the driver and passengers of a vehicle from the vibrations induced by road irregularities. This, however, is not the only reason for the use of a suspension system. According to Bastow and Howard (1993), maintaining contact between the wheels and the road surface is a far more fundamental issue as the vehicle's control and stability depends on it. So, suspension design requires concentration not only on ride comfort but also on handling characteristics. As ride and handling requirements are in conflict with each other, the design of suspension system characteristics like effective stiffness and damping require the determination of a compromise solution. While the well known quarter car model and higher order lumped parameter models used to represent the vehicle's overall suspension system are useful for preliminary work and initial design, suspension design work of any practical use has to take into account the physical details of the suspension system being used (double wishbone or McPherson strut type for example). While academic optimisation studies on suspension design and active suspension controller design can concentrate on the quarter car model (Cole, 2001; Yağız and Yüksek, 2001), one needs to base these optimisation and controller design studies on a much more accurate model of the vehicle's suspension system to be able to transfer the results to the automotive industry. Fortunately, such accurate models are quite readily implementable in the form of canned multibody dynamics programs like Adams® (Anon., 2001) and Simpack (Kortüm) or special purpose vehicle dynamics programs like Vedyna (Anon., 2000). The latter approach is taken in this paper. The suspension systems used are highly realistic models formed in Adams/Car® (Anon., 2001). This paper focuses on optimisation of suspension parameters and ride and handling properties and on implementation of active suspension control using an Adams/Car® suspension model. A first step in a suspension optimisation study is to determine which suspension variables can be varied and their