ANALYSIS OF SEMI-ACTIVE AND PASSIVE SUSPENSION SYSTEMS

Abstract

Vehicle suspension systems can be classified as passive, active and semi active suspensions. Passive systems have been widely used in vehicles for many years. Design of a passive suspension system has always been a challenging problem that requires a designer to simultaneously maintain a high standard of ride, handling, and body attitude control under different road conditions. Compared to passive suspensions, active systems can improve the performance of vibration isolation over a wider range of frequencies. In recent years, semi-active control suspension systems have become more popular because they have the advantages of low energy consumption and fabrication cost with vibration control performance similar to active systems. Semi-active systems can only dissipate system energy and have the advantage of being able to function in a passive mode if the control system has failed. Modeling of semi-active suspension system provides better insight in to the ability of the semi-active suspensions in improving the suspension performance. Present work aims at preparing a mathematical model of semi-active vehicle suspension system of a quarter-car model with Magneto rheological (MR) damper and air spring. The software used for this purpose is MATLAB/Simulink. Three different control laws are used to examine the performance of semi-active suspension system. Frequency responses of sprung mass acceleration, relative displacement and transient responses of sprung mass displacement are plotted for suspension systems working under different control laws. Responses of different suspensions systems are compared.