• Smart Structures and Systems
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• 제16권6호
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• pp.981-1002
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• 2015

For vibration control of civil structures, especially large civil structures, one of the important issues is how to place a minimal number of actuators and sensors at their respective optimal locations to achieve the predetermined control performance. In this paper, a methodology is presented for the determination of the minimal number and optimal location of actuators and sensors for vibration control of building structures under earthquake excitation. In the proposed methodology, the number and location of the actuators are first determined in terms of the sequence of performance index increments and the predetermined control performance. A multi-scale response reconstruction method is then extended to the controlled building structure for the determination of the minimal number and optimal placement of sensors with the objective that the reconstructed structural responses can be used as feedbacks for the vibration control while the predetermined control performance can be maintained. The feasibility and accuracy of the proposed methodology are finally investigated numerically through a 20-story shear building structure under the El-Centro ground excitation and the Kobe ground excitation. The numerical results show that with the limited number of sensors and actuators at their optimal locations, the predetermined control performance of the building structure can be achieved.

• Journal of Mechanical Science and Technology
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• 제17권1호
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• pp.11-22
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• 2003

In this paper, a method for optimal placement of sensors and actuators is presented by using new measures of modal controllability and observability defined in a balanced coordinate system. The proposed new measures are shown to have a great advantage in practical use when they are used as criteria for selecting the locations of sensors and actuators, since the most controllable and observable locations can be obtained to be identical. In addition, they are more accurate than the measures of Hamdan and Nayfeh in that the effects of the eigenvector norm are considered into the magnitude of measures. In simulations, to verify the effectiveness of the proposed measures and optimal placement method, the closed-loop response of a simply supported flexible beam, in which the number and locations of actuators are determined by using the proposed measures and optimal placement method, has been examined and compared with the case of Hamdan and Nayfeh’s measures.

• Smart Structures and Systems
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• 제15권4호
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• pp.1041-1062
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• 2015

In this paper a method of finding optimal positions for piezoelectric actuators and sensors on different structures is presented. The genetic algorithm and multi-objective genetic algorithm are selected for optimization and $H_{\infty}$ norm is defined as a cost function for the optimization process. To optimize the placement concerning the selected modes simultaneously, the multi-objective genetic algorithm is used. The optimization is investigated for two different structures: a cantilever beam and a simply supported plate. Vibrating structures are controlled in a closed loop with feedback gains, which are obtained using optimal LQ control strategy. Finally, output of a structure with optimized placement is compared with the output of the structure with an arbitrary, non-optimal placement of piezoelectric patches.

• Smart Structures and Systems
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• 제12권5호
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• pp.547-577
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• 2013

To suppress vibration and noise of mechanical structures piezoelectric ceramics play an increasing role as effective, simple and light-weighted damping devices as they are suitable for sensing and actuating. Out of the various piezoelectric damping methods this paper compares mode based active control strategies to passive shunt damping for thin plates. Therefore, a new approach for the optimal placement of the piezoelectric sensors/actuators, or more general transducers, is proposed after intense theoretical investigations based on the Kirchhoff kinematical hypotheses of plates; in particular, modal and nilpotent transducers are discussed in detail. Based on the proposed distribution a discrete design for modal transducers is implemented, tested and verified on an experimental setup. For active control the modal sensors clearly identify the eigenmodes, whereas the modal actuators impose distributed eigenstrains in order to reduce the transverse plate vibrations. In contrast to the modal control, passive shunt damping works without requiring additional actuators or auxiliary power and can therefore act as an autonomous system, but it is less effective compensating the flexible vibrations. Exemplarily, an acryl glass plate disturbed by an arbitrary force initialized by a loudspeaker is investigated. Comparing the different methods their specific advantages are highlighted and a significant broadband reduction of the vibrations of up to -20dB is obtained.

• 한국항공우주학회지
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• 제43권6호
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• pp.557-567
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• 2015

헬리콥터 진동의 주요 가진원 중 가장 결정적인 요인은 주로터이며 이러한 로터 유발진동은 승무원과 승객의 안락함을 보장하기 위해 회전익 항공기에서 해결해야할 과제 중 하나이다. 종래의 헬리콥터에서는 수동형 진동저감장치가 주로 사용되어 왔고 수리온 항공기에도 여러 가지 형태의 수동형 진동저감장치가 적용되어 있다. 최근 국외 항공기 제조업체에서는 수동형 진동저감장치 대비 작은 중량으로 우수한 진동저감 성능을 발휘할 수 있는 능동진동제어시스템(AVCS)의 적용을 확대하고 있는 추세이다. AVCS는 중량 절감외에도 항공기 형상, 비행 상태 변화 시에도 만족할만한 성능을 유지할 수 있는 장점이 있다. 이러한 AVCS를 수리온에 적용 시 어느 정도의 성능을 발휘하는지 확인하기 위한 성능시연 프로그램을 수행하였고, 최적의 센서와 작동기 조합을 찾기 위한 최적화 과정을 수행하였다. 지상 및 비행시험을 통해 계측된 데이터를 이용하여 최적의 센서 및 작동기 조합을 도출하고 비행시험 결과와 비교하였다.