\chapter{MECHATRONIC SUSPENSION SYSTEM MODELING and Its Application in Vehicles}
\label{ch:modelin}


\section{INTRODUCTION}
 and an approach for the vertical dynamic performance evaluation are given in Sections~\ref{sec:34ssr} and \ref{sec:35spe} respectively. In Section~\ref{sec:36md}, two classes of road excitation signals are introduced and appropriate disturbance models, which are utilized in the Chapters \ref{ch:mac}, \ref{ch:rbcont} and \ref{ch:wmmac}, are presented.

\section{VEHICLE SUSPENSION MODELLING }
\label{sec:32vsm}
 On one hand, a stiff suspension such as handling performance and suspension travel constraints are conflicted. Thus, many kinds of vehicle suspensions systems have been developed to improve both ride quality and handling performance.

A mechatronic suspension system can employ some pneumatic, magneto rheological , hydraulic or elctromagnatic actuators to generate the force to control this suspension system. With the development of microprocessors and electronics, many researchers \cite{Hrovat97,Appleyard95}  of active suspension control systems have been presented by \cite{Elmadany11,Nagai93,Kruczek10,Hrovat97,Genger09,Gavriloski07}. It should be noticed that ride comfort, road handling and suspension deflection are mainly used to evaluate the suspension performances. Generally speaking, ride comfort of the  is associated with the contact forces of tyres and road surface, and suspension deflection is referred to the displacement between the sprung mass and unsprung mass \cite{Lai02,Yamashita90}. In the past two decades, a great number of research projects have been carried out, targeting the challenge of how to improve the vehicle suspension systems performances \cite{Hrovat97}. Due to the inherent conflicting nature of the systems performance criteria, for instance, enhancing ride comfort needs larger suspension stroke and smaller damping of wheel-hop mode, and this results in a degradation in ride safety \cite{Liu05}. The problem, hence, is still open for a better solution to be excavated.\\


On one hand, a stiff suspension such as handling performance and suspension travel constraints are conflicted. Thus, many kinds of vehicle suspensions systems have been developed to improve both ride quality and handling performance.


\section{A QUARTER VEHICLE SUSPENSION MODEL}
\label{sec:33qvsm}

  \section{SUPENSION SYSTEM REQUIREMENTS}
  \label{sec:34ssr}
  \subsection{Ride Comfort}
    \label{subsec:34ssr1}
   see \citet{Hrovat97} and  vertical sprung mass acceleration (i.e. the acceleration sensed by vehicle passengers) $||\ddot{Z}_S ||_{RMS}$, which should be minimized. This is a widely used measure for ride comfort. A suspension system enhances ride comfort by isolating the sprung mass from the vibrations induced by the road or the dynamics of the vehicle. Thus, in terms of  acceleration of the sprung mass \cite{Heiring11}. However, to
  
  \section{SUSPENSION PERFORANCE EVALUATION }
  \label{sec:35spe}
  On one hand, a stiff suspension such as handling performance and suspension travel constraints are conflicted. Thus, many kinds of vehicle suspensions systems have been developed to improve both ride quality and handling performance.On one hand, a stiff suspension such as handling performance and suspension travel constraints are conflicted. Thus, many kinds of vehicle suspensions systems have been developed to improve both ride quality and handling performance.
  in this Thesis, the performance gain of a mechatronic suspension is given with respect to a reference system as
  \begin{align}
  P_{gain}=1-\frac{\left \| absP_{cont.} \right \|_i}{\left \| absP_{pass.} \right \|_i}
  \end{align}
  
  