William Schmitendorf

Active control of buildings subject to earthquake excitation

The objective of this research is to develop control algorithms and methods for active control of structures subjected to environmental loads, such as earthquakes, strong wind gusts, waves, etc. A great deal of progress has been made on robust control theory, using the infinity norm in the time domain framework. Successful application of the theory has been made to aerospace and mechanical systems. Until recently, these control methodologies have not been investigated and evaluated in control of civil engineering structures. These advanced control theories will be used advantageously to develop the control algorithms and methodologies in designing controllers for large buildings. The investigation includes:

• Robust control algorithms which account for uncertainty in parameter identification and modeling uncertainties for the structure.
• Control algorithms and methods which ensure the reliability of the control system when a number of sensors and/or actuators fail. The reliability of the control system refers to the ability of the control system, as driven by the control algorithm, to stay stable and provide certain prescribed level of performance in case of sensor and/or actuator failure.
• Techniques for the selection of actuator/sensor locations in control of large structures.
• Control algorithms for practical implementation, including optimization, compensation of time delays, static output feedback and acceleration feedback.

This research program involves multi-disciplinary expertise and it will have a significant impact on the control technologies for civil engineering structures. Test plans have been made for the verification of the results obtained in this study utilizing the shaking table tests and the existing full-scale test facilities. The research is being done in collaboration with Professor Jabbari.

Dynamic full state feedback compensation to increase robustness

This research addresses the problem of designing robust state feedback controllers; i.e. controllers which guarantee stability for all possible uncertainties within a given range. Using an example, we have shown, that if the uncertainty is time invariant, it is possible to increase the size of the uncertainty set for which stability is guaranteed by using a dynamic feedback controller. Our objective is to develop a theoretical basis and a computation technique for using dynamic state feedback in robust control design. Robust control design problems arise in aerospace vehicle guidance problems and in the design of lightweight space structures.

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