Geology Reference
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Figure 32. Base isolator and third-floor displacement and acceleration responses under Big Bear earth-
quake for integrator backstepping based MR damper monitoring
to 1.3729 m/s 2 in controlled case). The control
force provided by the MR damper and the cor-
responding input voltages to the MR damper are
shown in Figure 33. It is clear from the input
voltage time history shown in Figure 33 that only
a small amount current input is needed to mitigate
the vibration. Therefore, switching the input cur-
rent from zero to maximum based on system re-
sponses decreases the system performance under
seismic motions.
It is observed from above discussions that
worst control cases are seen in clipped optimal
and in GA based optimal FLC. The reason for
clipped optimal case is that it tries to provide a
full voltage supply or zero to the damper. There-
fore either it tries to over dampen the structure or
it provides less than required damping. When the
damper gets full voltage supply it tries to reduce
the displacement and that on the other hand in-
creases the acceleration at the base level.
This scenario is not seen in the cases of dynamic
inversion control and in integrator backstepping
control as they provide the required voltage to
the MR damper.
Figure 33. Voltage input and control force under
Big Bear earthquake for integrator backstepping
based MR damper monitoring
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