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標題: H∞直接輸出回饋之結構控制
H∞ Direct Output Feedback in Structural Control
作者: 潘銘棋
Pan, Ming-Chi
關鍵字: Earthquake Engineering;地震工程;Active Control;H-infinite Control;Time Delay;Direct Output Feedback;主動控制;H∞控制;時間延遲;直接輸出回饋
出版社: 土木工程學系

In this study, a H∞ direct output feedback control algorithm, through minimizing the entropy, a performance index measuring the tradeoff between the H∞ optimality and the H2 optimality, is applied to reduce the structural responses under seismic loads. The values of control parameters γ and α are selected based on the desired control efficiency. The decrease of γ or increase of α will result in better effectiveness in reducing structural responses, but larger control forces required to be applied. Larger α has to be selected for stiff structures to achieve the same control effectiveness than flexible structures.
For a SDOF damped structure, exact output feedback gains are derived. From the modal parameters, frequency domain and time domain analysis of the controlled system, we found that the control effectiveness of direct velocity output feedback control is similar to state feedback control. The control forces are then calculated from the multiplication of output measurements by time-invariant feedback gain matrix. Small number of sensors and simple on-line calculation made the proposed control algorithm favorable to real implementation.
In real active control, 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. In this study, explicit formulas are obtained to calculate the maximum allowable delay time to avoid system instability. In addition, a formula is also derived to determine the critical control weighting factor so as to make the system stability dominated by the lower mode, and hence the allowable delay time is significantly lengthened. In addition, the maximum delay, (td)max, for system instability can be increased with increasing structural original damping ratios or selecting small α in which the stability of control system are dominated by lower modes.
Appears in Collections:土木工程學系所

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