Quarter Car Simulation Using Matlab

Abstract—

MATLABSolutions demonstrate The objectives of this study are to obtain a mathematical model for the passive and active suspensions systems for quarter car model. Current automobile suspension systems using passive components only by utilizing spring and damping coefficient with fixed rates. Vehicle suspensions systems typically rated by its ability to provide good road handling and improve passenger comfort. Passive suspensions only offer compromise between these two conflicting criteria. Active suspension poses the ability to reduce the traditional design as a compromise between handling and comfort by directly controlling the suspensions force actuators. In this study, the Linear Quadratic Control (LQR) technique implemented to the active suspensions system for a quarter car model. Comparison between passive and active suspensions system are performed by using different types of road profiles. The performance of the controller is compared with the LQR controller and the passive suspension system.

Introduction

A car suspension system is the mechanism that physically separates the car body from the wheels of the car. The performance of the suspension system has been greatly increased due to increasing vehicle capabilities. Apple yard and Well stead (1995) have proposed several performance characteristics to be considered in order to achieve a good suspension system. Suspension consists of the system of springs, shock absorbers and linkages that connects a vehicle to its wheels. In other meaning, suspension system is a mechanism that physically separates the car body from the car wheel. The main function of vehicle suspension system is to minimize the vertical acceleration transmitted to the passenger which directly provides road comfort. Traditionally automotive Suspension designs have been compromise between the three conflicting criteria’s namely road handling, load carrying, and passenger comfort. The suspension system must support the vehicle, provide directional control using

handling manoeuvres and provide effective isolation of passengers and load disturbance. A passive suspension has the ability to store energy via a spring and to dissipate it via a damper. Its Parameters are generally fixed, being chosen to achieve a certain level of compromise between road handling, load carrying and ride comfort. An active suspension system has the ability to store, dissipate and to introduce energy to the system. It may vary its parameters depending upon operating conditions. There are three Types of suspension system; passive, semi-active and active suspension system. Traditional suspension consists springs and dampers are referred to as passive suspension, then if the suspension is externally controlled it is known as a semi active or active suspension. The passive suspension system is an open loop control system.