Title page for ETD etd-080399-151816


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
  • earthquakes
Date of Defense 1999-05-10
Availability unrestricted
Abstract
An 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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