Name: Monir Ahmad

English 259

Fall II 2018

Technical Writing

TTH 1-4:25PM

Professor Linda

A comparative study of semi- active control strategies
for base isolated buildings



Earthquake Resistance

Earthquake is a violent and sudden shock of the earth, which
is often caused by two layers of the ground slipping from one another.
Earthquakes are measured in accordance with their magnitudes. The earthquakes
with higher magnitudes have higher destruction levels. Scientists believe that
earthquakes can occur anywhere, anytime, and are unpredictable. The engineering
society believes there are no systems that can reduce the magnitude of the
earthquakes but they have several techniques that would protect the safety of
buildings in earthquakes.

There are several methods used in the control of semi-active
control which includes;

”Maximum energy dissipation algorithm and
modulated homogeneous friction algorithm”

The behavior of devices that are semi-active is mostly
nonlinear, and as such, one of the major challenges during application of this
technology is the appropriate development of control algorithm. A number of
algorithms are tested for use with the MR (Magneto rheological Damper), a
semi-active control device that’s been innovated and is quite promising to the
civil engineering applications. Discussion of each control system takes place
after simulation, with results indicating that the control systems’ performance
is dependent on the employed algorithm (Dyke and Spencer Jr., 1997).

”Sliding mode control”

SMC is a nonlinear control method
which forces a system slide over a cross-section of the systems’ normal
behavior through alteration of the nonlinear systems’ dynamics. The method can
switch from one continuous structure to another making the method a variable
structure method (Komatsu et al., 2007).

”Backstopping control technique and
quantitative feedback theory”

Suspension systems are crucial
even in vehicles. The suspension systems are designed to ensure the comfort of
the passengers, protect the chassis, and load. Suspensions have been designed
to mitigate uncomfortable and harmful vibrations through the use of dampers. In
cases where the suspension systems are used in semi-active controls, two
control methodologies are used in making use of magneto rheological dampers.
For the appropriate performance of these dampers, their nonlinear dynamics
requires the use of control methodologies that are nonlinear. The first
methodology involves the use of the backstopping technique. The other methodology
is the QFT (Quantitative Feedback Theory). Despite the fact that QFT is
designed for linear systems, it could also be used for nonlinear systems.
Achievement of this can only be possible in the event nonlinear dynamics are
represented as linear systems, with representations of uncertainties that are
approximately true with the behavior of the plant to be controlled (Zapateiro
et al., 2010).

”Force tracking”

Force tracking is a method used in
testing structures and facilities and is widely applied in seismic and civil
engineering. For there to be efficient suppression of the surplus force that
results from acceleration motion during the force control process, an FVFC
(Force and Voltage Feed forward Controller) and FIDOB (Feed forward Inverse
with Disturbance Observer) is presented. As an inner loop feed forward
controller, it constitutes the real-time control voltage signal and the
generated force feedback signal of the actuators’ acceleration as compensation
for the specimens’ acceleration motion for better disturbance rejection model.
The FVFC requires little information of the parameters or dynamic structure of
the system. FIDOB is then combined with FVFC to deal with remaining
disturbances as an outer-loop for the controlled testing of the electro-hydraulic
hybrid system. Therefore, there is an integration of the proposed controller
advantages of FVFC controller and FIDOB in terms of high tracking performance
and easy implementation. The uniaxial electro-hydraulic hybrid test rig is used
to carry out comparative experiments, with the effectiveness of the proposed
control strategy being seen from the results from the xPC rapid prototyping
technology and experiments (Dyke and Spencer Jr., 1997). 


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