Modelling and simulation of motor vehicle suspension system

Abstract

In this work, using a quarter-car model was adopted, the equations of motion were derived for a passive and then the sky-hook semi-active suspension systems. The derived differential equations, solved using the Dormand-Prince pair numerical formula, was then used to simulate values of displacements as affected by damping coefficients and the sky-hook constant. The simulated results showed that the maximum amplitude of the sprung mass, which is linked to ride discomfort, increases while those of unsprung masses, which affects the road holding ability, decreases with increasing depth of pothole. Furthermore, displacements for both sprung and unsprung masses varied directly with damping coefficient. Finally, as the sky-hook constant of the semi active system model increases, values of amplitudes of unsprung masses decreases while those of sprung masses increases. It was, thus, shown that the vertical displacements of vehicle bodies and wheels are dependent on the depth of potholes, damping coefficient and sky-hook constant, and that the sky-hook semi-active suspension system model gave a better result compared to the passive suspension system. Therefore, by applying the sky-hook control principle, the desired road comfort of passengers can be achieved as well as reduced rate of car damage and cost of maintenance.