This paper presents an active suspension system for passenger cars, using l
inear and fuzzy-logic controls. The model is described by a nonlinear syste
m with four degrees of freedom, subject to irregular excitation from a road
surface. The active control is the sum of two kinds of control. The former
is obtained by vertical acceleration of the vehicle body as the principal
source of control, and the latter is obtained by using fuzzy-logic control
as the complementary control. In the derivation of fuzzy control rules, lin
ear combinations of the vertical and rotary velocities and displacements of
the vehicle body are denoted as the input variables. The simulation result
s indicate that the proposed active suspension system proves to be very eff
ective in the vibration isolation of the vehicle body. (C) 1999 Elsevier Sc
ience Ltd. All rights reserved.