• 한국소음진동공학회논문집
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• 제23권5호
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• pp.445-455
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• 2013

A new linearization model for MR dampers is analyzed. The nonlinear hysteretic damping force model of MR damper can be modeled as a hyperbolic tangent function of currents, positions, and velicities, which is an algebraic function with constant parameters. Model parameters can be identified with numerical method using experimental force-velocity-position data obtained from various operating conditions. The nonlinear hysteretic damping force can be linearized with a given slope of damping coefficient if there exist corresponding currents to compensate for the nonlinearity. The corresponding currents can be calculated from the inverse model when the given linear damping force is set equal to the nonlinear hysteretic damping force. The linearization controller is realized in a DSP controller such that the corresponding currents to satisfy a given damping coefficient should be calculated. Experiments show that the current inputs to the MR damper produce linearized damping force with a given slope of the damping coefficient.

• 한국공간구조학회논문집
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• 제12권4호
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• pp.99-108
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• 2012

In recently, sky-bridge are often applied to high-rised adjacent buildings for pedestrian bridge. the seisnic response control of adjacent buildings have been studied and magneto-rheological(MR) fluid dampers have been applied to seismic response control. In this study, vibration control effect of the MR damper connected adjacent buildings has been investigated. Adjacent building structures with different natural frequencies were used as example structures. Two typed of control methods, displacement based or velocity based, are applied to determinate control force of MR damper. In this numerical analysis, it has been shown that displacement-based control algorithm is more effective than velocity-based control algorithm for seismic response control of adjacent buildings. And, when displacement-based control method is applied to control of adjacent buildings, the control of building occurred large displacement is more efficient in reducing the seismic response.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2003년도 춘계 학술발표회논문집
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• pp.473-480
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• 2003

A new semiactive control strategy for seismic response reduction using a neuro-controller and a magnetorheological (MR) fluid damper is proposed. The proposed control system adopts a clipped algorithm which induces the MR damper to generate approximately the desired force. The improved neuro-controller, which was developed by employing the training algorithm based on a cost function and the sensitivity evaluation algorithm replacing an emulator neural network, produces the desired active control force, and then by using the clipped algorithm the appropriate command voltage is selected in order to cause the MR damper to generate the desired control force. The simulation results show that the proposed semiactive neuro-control algorithm is quite effective to reduce seismic responses. In addition, the semiactive control system using MR fluid dampers has many attractive features, such as bounded-input, bounded-output stability and small energy requirements. The results of this investigation, therefore, indicate that the proposed semiactive neuro-control strategy using MR fluid dampers could be effective used for control seismically excited structures.

• Smart Structures and Systems
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• 제20권5호
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• pp.619-636
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• 2017

Magnetorheological (MR) damper is a type of controllable device widely used in vibration mitigation. This device is highly nonlinear, and exhibits strongly hysteretic behavior that is dependent on both the motion imposed on the device and the strength of the surrounding electromagnetic field. An accurate model for understanding and predicting the nonlinear damping force of the MR damper is crucial for its control applications. The MR damper models are often identified off-line by conducting regression analysis using data collected under constant voltage. In this study, a MR damper model is integrated with a model for the power supply unit (PSU) to consider the dynamic behavior of the PSU, and then a real-time nonlinear model updating technique is proposed to accurately identify this integrated MR damper model with the efficiency that cannot be offered by off-line methods. The unscented Kalman filter is implemented as the updating algorithm on a cyber-physical model updating platform. Using this platform, the experimental study is conducted to identify MR damper models in real-time, under in-service conditions with time-varying current levels. For comparison purposes, both off-line and real-time updating methods are applied in the experimental study. The results demonstrate that all the updated models can provide good identification accuracy, but the error comparison shows the real-time updated models yield smaller relative errors than the off-line updated model. In addition, the real-time state estimates obtained during the model updating can be used as feedback for potential nonlinear control design for MR dampers.

• 한국전산구조공학회논문집
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• 제20권6호
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• pp.761-767
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• 2007

건축 및 토목 구조물의 진동 제어분야에서 중앙집중식 제어방식은 주어진 목표응답수준을 만족시키기 위해서 전력공급, 센서, 그리고 감쇠기 등을 포함하는 복잡한 제어시스템을 구축하고 유지하는 노력이 필요하고, 구조물 유한요소모델의 큰차수, 모델의 불확실성, 가력장치의 제한 등의 이유로 적용성의 한계가 있다. 본 논문에서는 센서 혹은 컴퓨터없이 준능동 MR 감쇠기가 설치된 층만의 정보에 의해 제어력이 생성되는 분산제어식 응답의존형 MR 감쇠기가 제안하였다. 제안된 분산제어식 응답의존형 MR 감쇠기는 구조물의 층전단력에 대한 가변마찰력 크기 비의 변화에 따라 지진하중을 받는 구조물의 제어성능이 수동인 경우와 비선형 시간이력해석을 통해 비교 평가되었다. 마지막으로 일반 제어이론에서 널리 이용되는 중앙집중식 LQR 알고리듬과 본 논문에서 제안된 분산제어식 응답의존형 MR감쇠기가 3층 전단형 구조물을 대상으로 수치해석을 통해 비교 평가됨으로써 제안된 알고리즘의 유효성을 검증하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 추계학술대회 논문집
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• pp.947-948
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• 2010

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2000년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 2000
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• pp.496-500
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• 2000

대형 구조물의 진동제어를 위하여 MR 유체 댐퍼를 사용한 반능동 제어기법에 대하여 연구하였다. 기존에 많이 사용되고 있는 수동제어기법은 일단 제어장치를 설치한 후에는 구조물에 실제로 작용하고 있는 외부 하중의 현재 특성에 대해서 적절히 반응할 수 없다는 제한을 가지고 있으며, 이를 극복하기 위하여 연구되어온 능동제어기법은 구조물이 진동을 감소시키기 위하여 구조물에 직접적으로 가해지는 커다란 제어력을 요구하며, 이로 인해 경우에 따라서는 불안정한 상태가 유발될 수도 있다는 점이 단점으로 지적되고 있다. 최근에 Spencer 등은 반능동 제어기법을 제안하였는데, 이는 수동제어장치의 제어특성을 On-Line 으로 조절하는 방식으로서 제어 가능한 수동제어기법으로도 불리운다. 구조물의 진동제어에 필요한 제어력이, 특수한 제어기구에서 발생되는 인위적인 힘이 아니라, 적절한 구조부재에서 발생되는 자연적인 부재력이므로, 무엇보다 강인하고 신뢰할 수 있는 제어기법이며, 이때 제어장치의 구조적 특성을, 측정된 구조물의 응답에 맞추어 적절히 조절함으로써 다양한 외부하중에 대해 보다 효율적인 제어가 이루어질 수 있도록 한 방법이다. 반능동제어를 위한 제어기로서는 Variable Orifice Dampers, Friction Controllable Isolators, Variable Stiffness Devices, Electro-Rheological (ER) Fluid Damper, Magneto-Rheological(MR) Fluid Damper등이 제안되고 있으며, 본 논문에서는 반응속도가 빠르고, 적은 파워만을 요구하며, 커다란 제어력을 낼 수 있는 MR Damper를 사용하여 지진하중을 받는 구조물의 반능동 제어게 대하여 연구하였다. MR Damper의 특성이 비선형이므로 이에 적합한 Sliding Mode Fuzzy Control(SMFC)기법을 사용하였으며 이때 SMFC 의 최적 설계를 위하여 Genetic Algorithm을 적용하였다. 제안된 제어기법의 실제 적용성을 검증하기 위하여 기존이 제어결과와 비교 검토하였으며, 그 결과로부터 MR Damper를 사용한 반능동 제어기법이 구조물의 진동제어에 매우 효과적임을 확인할 수 있었다.

• 한국정밀공학회지
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• 제17권10호
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• pp.69-76
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• 2000

Lots of semi-active control devices have been developed in recent years because they have the best features of passive and active system. Especially, controllable magneto-rheological(MR) fluid devices have received significant attention in these area of research. The MR fluid is the material that reversibly changes from a free-flowing, linear viscous fluid to a semisolid with a controllable yield strength in milliseconds when exposed to a magnetic field. If the magnetic field is induced by moving a permanent magnet instead of applying current to a solenoid, it is possible to design a MR damper consuming low power because the power consumption is reduced at steady state. This paper proposes valve mode MR damper using permanent magnetic circuit that has wide range of operation with low power consumption, a design parameter is adopted. The magnetic circuit, material of choke and choke type are selected experimentally with the design parameter. The behaviors of the damper are examined and torque tracking control using PID feedback controller is performed for step, ramp and sinusoidal trajectiories.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2008년도 춘계학술대회 논문집
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• pp.1009-1010
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• 2008

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2007년도 춘계학술대회 논문집
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• pp.43-44
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• 2007