Type of Document Master's Thesis Author Scruggs, Jeffrey URN etd-080399-151816 Title Active, Regenerative Control of Civil Structures Degree Master of Science Department Electrical and Computer Engineering Advisory Committee
Advisor Name Title Lindner, Douglas K. Committee Chair Mili, Lamine M. Committee Member Ramu, Krishnan Committee Member Singh, Mahendra P. Committee Member Keywords
- structural control
- regenerative actuation
- proof-mass actuators
Date of Defense 1999-05-10 Availability unrestricted AbstractAn analysis is presented on the use of a proof-mass actuator as a
regenerative force actuator for the mitigation of earthquake
disturbances in civil structures. A proof-mass actuator is a machine
which accelerates a mass along a linear path. Such actuators can
facilitate two-way power flow. In regenerative force actuation, a bi-
directional power-electronic drive is used to facilitate power flow
both to and from the proof-mass actuator power supply. With proper
control system design, this makes it possible to suppress a disturbance
on a structure using mostly energy extracted from the disturbance
itself, rather than from an external power source.
In this study, three main objectives are accomplished. First, a new
performance measure, called the "required energy capacity," is proposed
as an assessment of the minimum size of the electric power supply
necessary to facilitate the power flow required of the closed-loop
system for a given disturbance. The relationship between the required
energy capacity and the linear control system design, which is based on
positive position feedback concepts, is developed. The dependency of
the required energy capacity on hybrid realizations of the control law
are discussed, and hybrid designs are found which minimize this
quantity for specific disturbance characteristics.
As the second objective, system identification and robust estimation
methods are used to develop a stochastic approach to the performance
assessment of structural control systems, which evaluates the average
worst-case performance for all earthquakes "similar" to an actual data
record. This technique is used to evaluate the required energy
capacity for a control system design.
In the third objective, a way is found to design a battery capacity
which takes into account the velocity rating of the proof-mass
actuator. Upon sizing this battery, two nonlinear controllers are
proposed which automatically regulate the power flow in the closed-loop
system to accommodate a power supply with a finite energy capacity,
regardless of the disturbance size. Both controllers are based on a
linear control system design. One includes a nonlinearity which limits
power flow out of the battery supply. The other includes a
nonlinearity which limits the magnitude of the proof-mass velocity.
The latter of these is shown to yield superior performance.
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