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Experimental validation of novel structural control algorithms is a vital step in both developing and building acceptance
for this technology. Small-scale experimental test-beds fulfill an important role in the validation of multiple-degree-offreedom
(MDOF) and distributed semi-active control systems, allowing researchers to test the control algorithms,
communication topologies, and timing-critical aspects of structural control systems that do not require full-scale
specimens. In addition, small-scale building specimens can be useful in combined structural health monitoring (SHM)
and LQG control studies, diminishing safety concerns during experiments by using benchtop-scale rather than largescale
specimens. Development of such small-scale test-beds is hampered by difficulties in actuator construction. In order
to be a useful analog to full-scale structures, actuators for small-scale test-beds should exhibit similar features and
limitations as their full-scale counterparts. In particular, semi-active devices, such as magneto-rheological (MR) fluid
dampers, with limited authority (versus active mass dampers) and nonlinear behavior are difficult to mimic over small
force scales due to issues related to fluid containment and friction. In this study, a novel extraction-type small-force (0-
10 N) MR-fluid damper which exhibits nonlinear hysteresis similar to a full-scale, MR-device is proposed. This actuator
is a key development to enable the function of a small-scale structural control test-bed intended for wireless control
validation studies. Experimental validation of this prototype is conducted using a 3-story scale structure subjected to
simulated single-axis seismic excitation. The actuator affects the structural response commanded by a control computer
that executes an LQG state feedback control law and a modified Bouc-Wen lookup table that was previously developed
for full-scale MR-applications. In addition, damper dynamic limitations are characterized and presented including force
output magnitude and frequency characteristics.
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