The ASCE Committee on Structural Control sponsored a session at the 1997 Structures Congress entitled "Structural Control: A Benchmark Comparison." The session brought together a group of highly qualified researchers to study a well defined benchmark problem. The purpose of this exercise was to have a basis for assessing the relative effectiveness and implementability of various structural control algorithms and to provide an analytical testbed for evaluation of control design issues such as model order reduction, spillover, control-structure interaction, limited control authority, sensor noise, available measurements, computational delay, etc. The session represented an initial step toward development of a standard by which to validate software and hardware for structural control systems.
The session consisted of five papers. The first paper provided an overview and definition of the benchmark problem. The remaining four papers applied various control strategies to this problem and discussed the ability of the respective approaches to meet performance specifications while not violating control constraints.
The papers were as follows (click on a paper title to go to the paper in format):
Abstract: Tremendous progress has been made over the last two decades toward making active structural control a viable technology for enhancing structural functionality and safety against natural hazards such as strong earthquakes and high winds. Over the years, many control algorithms and devices have been investigated, each with its own merits, depending on the particular application and desired effect. Clearly, the ability to make direct comparisons between systems employing these algorithms and devices is necessary to focus future efforts in the most promising directions and to effectively set performance goals and specifications.
This paper presents the overview and problem definition for a
benchmark structural control problem that can be used to evaluate
the relative effectiveness and implementability of structural
control algorithms and to provide an analytical testbed for
evaluation of various control design issues. The structure
considered -- chosen because of the widespread interest in this
class of systems (Soong 1990; Housner, et al. 1994; Fujino, et al.
1996) -- is a scale model of a three-story building employing an
active mass driver. A model for this structural system, including
the actuator and sensors, has been developed directly from
experimentally obtained data and will form the basis for the
benchmark study. Control constraints and evaluation criteria are
presented for the design problem. A simulation program has been
developed and made available to facilitate comparison of the
efficiency and merit of various control strategies. This benchmark
problem can be viewed as an initial step toward development of
standardized performance evaluation procedures.
Abstract: In this paper, both the methods of
continuous sliding mode control (CSMC) and continuous
sliding mode control with a compensator (CSMC&C) are applied
to a benchmark problem; namely, an active mass driver system. For
these control strategies, salient features of the controller design
and their merit are described. Simulation results based on
CSMC and CSMC&C are presented and compared with that
of the LQG method. It is demonstrated that the control
performances of CSMC and CSMC&C are quite comparable
to that of LQG.
Abstract: This paper presents a low order
controller design method, using closed loop modeling plus
covariance control, with application to the benchmark problem in
structural control for the active mass driver system at the
University of Notre Dame. This method finds a satisfactory
controller by iterating between closed loop modeling and covariance
control. The closed loop modeling implies that the model used for
model-based control design is extracted from the feedback system of
the last iteration.
Abstract: This study develops an active control
methodology for the AMD benchmark problem of Spencer et al.
(1997) based on dynamic output feedback controllers designed using
an H-infinity based approach. Kalman filter
estimators of the states of a reduced order model of the benchmark
structure are coupled to static state feedback controller gains to
develop the dynamic feedback controllers. A method is outlined for
designing H-infinity feedback controller gains,
and a comparison is made between the effectiveness of
H-infinity static output feedback and the dynamic
acceleration feedback controllers. The results quantify the
performance increase obtained with the additional complexity of the
dynamic output feedback controllers compared to the static
acceleration feedback controllers.
Abstract: The structured singular value (µ) synthesis technique is used to design controllers for the Active Mass Damper (AMD) Benchmark problem. In addition to stated performance objectives, robustness of the controllers to high frequency unmodeled dynamics (the neglected high frequency modes of the evaluation model), modeling error in the actuator dynamics and variations in the first structural natural frequency and damping value are considered in the design. The resulting controller achieves similar performance levels on the nominal evaluation model and the evaluation model with significant changes in its first natural frequency and damping value.
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