Abstract-- In this paper, passive and semi- active suspensions
system of a magnetorheological fluid damper for an
automobile application under different excitations (step,
sinusoidal, and random) as road profiles is studied. This work
is presented in two parts, the dynamic responses of the MR
fluid damper under the expiation are presented in the first part
and developing a simple and efficient controller to control the
damper behavior is presented in the second one. Bingham
plastic model is adopted for the mathematical modeling and
analyze the hysteretic behavior of the MR fluid damper. LQR
algorithm is used for the control processes. The results showed
that the input current to the magnetic circuit plays an
important role regarding the dynamic response and damping
force for the excitation, however, current effect is different for
the excitations. Magnetic saturation is noticed in the dynamic
response. Damping force can be controlled by controlling the
input current to reduce the overshoot, steady-state error, and
steady state time response. In addition, the linear quadratic
regulator (LQR) has successfully stabilized the system and
removes the vibration without any abnormal behavior.