Independent Suspension System, Modeling and Analysis of Multi-axle Vehicle

Abstract

Suspension system of the vehicle separates the vehicle body from road’s irregularities. If suspension system is not present, road shocks and vibration affect the passenger and payload. Independent, dependent and semi-independent suspension systems are used in vehicles depending upon the type of vehicle. Independent suspension system performs better off road and 3D road profile and in heavy vehicles it is preferred than other types of suspension systems. Independent suspension provides better roll over resistance and contact patch novel forces. Independent suspension system controls three types of vehicle motions including pitch, roll and heave. Mathematical models for two axle vehicle with four independent suspension systems are available in literature as the classical case. Mathematical models of multi-axle vehicle are required to develop their design and for simulation purposes. Design parameters set according to the system requirements affect the performance of vehicle’s suspension. A complete mathematical model is required to evaluate the suspension system behavior. System becomes complicated with axles more than two requiring independent suspensions more than four. This thesis presents the 11-DOF full-car model of a four axle vehicle with eight independent suspensions. Overall system is based on eight passive type suspensions operating independently to handle the vehicle vibrations. Generic mathematical model in index notation is also developed to design a system with n number of axles. Model is implemented in MATLAB Simulink to generate the behavior of heave, pitch and roll on different road inputs and results are compared with a commercial software simulation results.