• 한국자동차공학회논문집
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• 제19권2호
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• pp.57-65
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• 2011

In this paper, a hydropneumatic modeling and dynamic analysis of a heavy truck semi-active cabin air suspension system is presented. Semi-active cabin air suspension system improves driver's ride comfort by controlling the damping characteristics in accordance with driving situation. So it can reduce vibration between truck frame and cabin. Semi-active cabin air suspension system is consist of air spring, leveling valve and CDC shock absorber, and full cabin system are mathematically modelled using AMESim software. Simulation results of components and full cabin system are compared with experimental data of components and test results of a cabin using 6 axis simulation table. It is found that the simulation results are in good agreements with test results, and the hydropneumatic model can be used well to predict dynamic characterics of heavy truck semi-active cabin air suspension system.

• Smart Structures and Systems
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• 제15권4호
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• pp.963-995
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• 2015

The effectiveness of the various control algorithms for semi-active structural control systems proposed in the literature is highly questionable when dealing with earthquake actions, which never reach a steady state. From this perspective, the paper summarizes the results of an experimental activity aimed to compare the effectiveness of four different semi-active control algorithms on a structural mock up representative of a class of structural systems particularly prone to seismic actions. The controlled structure is a near full scale 2-story steel frame, equipped with two semi-active bracing systems including two magnetorheological dampers designed and manufactured in Europe. A set of earthquake records has been applied at the base of the structure, by utilizing a shaking table facility. Experimental results are compared in terms of displacements, absolute accelerations and energy dissipation capability. A further analysis on the percentage incidence of undesired and/or unpredictable operations corresponding to each algorithm gives an insight on some factors affecting the reliability and, in turn, the real effectiveness of semi-active structural control systems.

• Smart Structures and Systems
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• 제18권4호
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• pp.683-705
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• 2016

A semi-active algorithm for edgewise vibration control of the spar-type floating offshore wind turbine (SFOWT) blades, nacelle and spar platform is developed in this paper. A tuned mass damper (TMD) is placed in each blade, in the nacelle and on the spar to control the vibrations for these components. A Short Time Fourier Transform algorithm is used for semi-active control of the TMDs. The mathematical formulation of the integrated SFOWT-TMDs system is derived by using Euler-Lagrangian equations. The theoretical model derived is a time-varying system considering the aerodynamic properties of the blade, variable mass and stiffness per unit length, gravity, the interactions among the blades, nacelle, spar, mooring system and the TMDs, the hydrodynamic effects, the restoring moment and the buoyancy force. The aerodynamic loads on the nacelle and the spar due to their coupling with the blades are also considered. The effectiveness of the semi-active TMDs is investigated in the numerical examples where the mooring cable tension, rotor speed and the blade stiffness are varying over time. Except for excessively large strokes of the nacelle TMD, the semi-active algorithm is considerably more effective than the passive one in all cases and its effectiveness is restricted by the low-frequency nature of the nacelle and the spar responses.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2002년도 가을 학술발표회 논문집
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• pp.313-320
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• 2002

A new semi-active control strategy for seismic response reduction using a neuro-controller and a magnetorheological (MR) fluid damper is proposed. The proposed control system consists of the improved neuro-controller and the bang-bang-type controller. 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 the bang-bang-type controller causes the MR fluid damper to generate the desired control force, so long as this force is dissipative. In numerical simulation, a three-story building structure is semi-actively controlled by the trained neural network under the historical earthquake records. The simulation results show that the proposed semi-active neuro-control algorithm is quite effective to reduce seismic responses. In addition, the semi-active control system using MR fluid dampers has many attractive features, such as the bounded-input, bounded-output stability and small energy requirements. The results of this investigation, therefore, indicate that the proposed semi-active neuro-control strategy using MR fluid dampers could be effectively used for control of seismically excited structures.

• 한국지진공학회논문집
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• 제9권6호
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• pp.75-90
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• 2005

사장교의 효과적 지진응답제어를 위하여 MR 감쇠기를 이용한 준능동 퍼지 제어기법을 제시하였다. 제시하는 방법은 MR 감쇠기의 응답정보만을 이용한 퍼지추론 과정을 통하여 준능동 제어를 수행하는 방법으로서, 능동제어이론에 기반한 기존 준능동 제어기법과 달리, 별도의 능동제어기를 설계할 필요가 없는 간단한 구조로서 구성될 수 있다. 제시한 제어기법의 제어성능을 평가하기 위해 사장교 벤치마크 문제에 적용하였으며 기존 준능동 제어기법들과의 성능비교를 통하여 그 효율성을 평가하였다. 제어성능을 비교한 결과, 제시하는 준능동 퍼지 제어기법은 주탑의 전단력 및 휨모멘트, 데크의 수평변위, 그리고 케이블 장력 등의 상충하는 지진응답들을 동시에 효과적으로 제어함으로써 지진응답제어에 매우 효율적인 제어전략이 될 수 있음을 보였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.191-194
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• 1997

Passive, semi-active and active dampers have been used to dissipate energy in mechanical systems. Semi-active dampers have higher performance than passive dampers and require lower power to operate than active dampers. Its damping characteristics can be changed appropriately for varying conditions. In this paper, we developed a semi-active damper based on Magnetorheological(MR) fluid. MR fluid has a variable damping characteristics proportional for the magnetic field intensity. It has several advantages such as high strength, low viscosity, robustness in impurities and wide temperature range of operational stability. We designed a constrained rotary MR damper base on valve mode which can dissipate more energy per unit volume. The system with Bingham characteristics is obtained and proved by the experiment.

• International Journal of Aeronautical and Space Sciences
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• 제15권1호
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• pp.1-19
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• 2014

Attaching a piezoelectric transducer to a vibrating structure, and shunting it with an electric circuit, gives rise to different passive, semi-passive, and semi-active control techniques. This paper attempts to review the research related to structural vibration control, via passive, semi-passive, and semi-active control methods. First, the existing electromechanical modeling is reviewed, along with the modeling methods. These range from lumped parameters, to distributed parameters modeling of piezostructural systems shunted by electrical networks. Vibration control laws are then discussed, covering passive, semi-passive, and semi-active control techniques, which are classified according to whether external power is supplied to the piezoelectric transducers, or not. Emphasis is placed on recent articles covering semi-passive and semi-active control techniques, based upon switched shunt circuits. This review provides the necessary background material for researchers interested in the growing field of vibration damping and control, via shunted piezostructural systems.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 추계학술대회논문집
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• pp.282-286
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• 2000

In this paper, magneto-rheological(MR) damper is studied for vibration control of large infra structures under earthquake. Generally, active control devices need a large control force and a high power supply system to reduce the vibration effectively. Large and miss tuned control force may induce the dangerous situation such that the generated large control force acts to amplify the structural vibration. Recently, to overcome the weaknesses of the active control, the semi-active control method is suggested by many researchers. Semi-active control uses the passive control device of which the characteristics can be modified. Control force of the semi-active device is not generated from the actuator with power supply. It is generated as a dynamic reaction force of the device same as in the passive control case, so the control system is inherently stable and robust. Unlike the case of passive control, control force of semi-active control is adjusted depending on the measured response of the structure, so the vibration can be reduced more effectively against various unknown environmental loads. Magneto-rheological(MR) damper is one of the semi-active devices. Dynamic characteristics of the MR material can be changed by applying the magnetic fields. So the control of MR damper needs only small power. Response time of MR to the input voltage is very short, so the high performance control is possible. MR damper has a high force capacity so it is adequate to the vibration control of large infra structure. Because MR damper has a nonlinear property, normal control method used in active control may not be effective. Clipped optimal control, modified bang-bang control etc. have been suggested to MR damper by many researchers. In this study, sliding mode fuzzy control(SMFC) is applied to MR damper. Genetic algorithm is used for the controller tuning. To verify the applicability of MR damper and suggested algorithm, numerical simulation on the aseismic control is carried out. Simulation model is three-story building structure, which was used in the paper of Dyke, et al. The control performance is compared with clipped optimal control. The present results indicate that the SMFC algorithm can reduce the earthquake-induced vibration very effectively.

• 한국항공우주학회지
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• 제38권9호
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• pp.882-889
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• 2010

수동형 진동제어 방식과 같이 시스템이 안정되며, 수동형에 비해 높은 제진 효과가 기대되는 반능동 진동제어 방식은 시스템의 안정화가 요구되는 우주구조물의 제진방법에 유효한 진동제어 방식중 하나이다. On-Off 제어방식에 근거한 반능동 제어는 On-Off 스위칭 시에 전달력의 불연속성으로 인한 chattering을 발생시킬 수 있으며, 이는 탑재체 구조물의 고유진동수와의 커플링으로 인하여 지향성능을 저하시키는 원인으로 작용할 수 있다. 본 논문에서는 chattering 영향 최소화를 통한 지향성능향상을 목적으로 LQ(Linear Quadratic)이론에 기반한 가변 감쇠형 반능동 제어기법을 제안하였다. 시뮬레이션 결과는 본 논문에서 제안한 반능동 제어기법은 기존의 skyhook와 LQ를 기반으로 하는 Bang-Bang 반능동 제어기법과 비교하여 높은 진동절연 성능을 나타내고 있다.

• 한국지진공학회논문집
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• 제9권4호
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• pp.43-54
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• 2005

다양한 지진 규모 및 주파수 특성을 가지는 지반운동에 대하여 사장교에 장착된 준능동 제어시스템의 제어효과를 분석하고 비용효율성을 평가하였다. Dyke 등에 의하여 제시된 벤치마크 사장교 제어문제에 준능동 제어시스템을 설계하였으며, LQG 최적제어기에 기반한 bi-state 제어방법을 적용하였다. 제어시스템의 비용효율성은 제어시스템을 장착하지 않은 교량의 생애주기 비용에 대한 제어시스템을 장착한 교량의 생애주기비용의 비로서 정의하였으며, 손상비용 규모와 준능동 제어장치의 가격을 매개변수로 하여 그 변화에 따른 비용효율성 평가를 수행하였다. 분석 결과, 제어시스템의 경제적 효율성은 준능동 제어장지의 가격에 크게 민감하지 않은 반면, 손상비용 규모에 따라 민감하게 변화하였다. 또한 중진규모의 연약지반과 강진규모의 견고한 지반에 해당하는 지반운동에 대하여 준능동 제어시스템의 비용효율성이 높은 것으로 평가되었다.