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Vibration reduction and stability analysis of H_infinite active control systems
|關鍵字:||active control;主動控制;time delay;active tendon;時間延遲;主動鋼鍵||出版社:||土木工程學系||摘要:||
In this study,H-infinite control algorithm is applied to reduce the structural responses under seismic loads. Two kinds of controlled outputs, named “displacement controlled output” and “energy controlled output” are presented to design the optimal controller for structures equipped with active tendon systems. The value of parameters alpha and gamma are selected based on the desired control efficiency. The decrease of alpha or increase of gamma will result in larger control forces and better effectiveness in reducing structural responses. Larger has to be selected for stiff structures to achieve the same control effectiveness than flexible structures.
The influence of structural modeling error on the accuracy of estimating controlled frequencies and damping ratios was also investigated. It is found that control system with displacement controlled output are primarily affected by the errors of structural fundamental period, whereas the “energy controlled output” systems are more sensitive to the errors of structural original damping ratio.
In active control systems, control force execution time delay cannot be avoided. Small delay time not only can render the control ineffective, but also may cause the system instability. The maximum delay time for system instability increased with increasing structural original damping ratios or selecting smaller alpha in which the stability of control system are dominated by lower modes. In the final part of this thesis, an optimal time-delayed H-infinite control algorithm is developed for discrete-time systems. According to the proposed control algorithm, the structural system is assured to remain stable and the control effectiveness is not degraded even with the presence of time delay.
|Appears in Collections:||土木工程學系所|
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