• 제어로봇시스템학회논문지
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• 제8권10호
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• pp.861-866
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• 2002

A seat suspension system with a controlled MR(Magneto Rheological) fluid damper is introduced to improve the ride quality and prevent the health risk of a driver compared to fixed seats. The system is located between a seat cushion and the base, and is composed of a spring, MR fluid damper and controller. The MR fluid damper designed in valve mode is capable of producing a wide range of damping force according to applied currents. In experiments, a person was sitting on the controlled seat excited by a hydraulic system The skyhook control, continuous skyhook control and relative displacement control were applied and the continuous skyhook control improved the vibration suppression by 36.6%.

• 유공압시스템학회논문집
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• 제1권1호
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• pp.17-22
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• 2004

The goal of this paper is to improve the position control performance of pneumatic rotary actuator with variable brake using Magneto-Rheological Fluid. The air compressibility and the lack of damping of the pneumatic actuator bring the dynamic delay of the pressure response and cause the oscillatory motion. In this study, a variable rotary brake comprising Magneto-Rheological Fluid is equipped to the joint of a pneumatic manipulator. Experiments of step response have proved that the transient response of the manipulator could be improved compared with that of the conventional control algorithm by using a phase plane switching control algorithm.

• 제어로봇시스템학회논문지
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• 제4권1호
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• pp.26-31
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• 1998

For the semiactive vibration control, a variable damper and proper control systems are essential. In this research, a controllable damper was designed using the MR fluids and its mechanical properties such as damping constant and response time were measured. Since the response time of the MR damper was much longer than nominal MR fluid response time, the time delay of the damper should be considered in the design of controllers. It is shown that the advanced On/Off vibration control which includes the damper time delay performs more effectively than the conventional one.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2006년도 학술발표회 논문집
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• pp.495-502
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• 2006

Seismic performance of semi-active fuzzy control algorithm to operate MR dampers for coupling adjacent building is investigated in this paper. In the proposed semi-active control technique, the fuzzy logic is used as a method to adjust input voltage to MR damper. In order to validate control performance of proposed technique, the seismic performance of the semi-active fuzzy control system is compared with that of passive control system where the input voltage to MR damper is set to display maximum damping force. The simulated results show that the semi-active fuzzy control technique effectively regulates the trade-off existing between seismic responses of two buildings subject to various earthquake excitations.

• 한국강구조학회 논문집
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• 제24권1호
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• pp.91-99
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• 2012

최근 인접 건축물의 진동제어와 관련된 연구가 몇몇 연구자에 의하여 수행되고 있으며 그리고 구조물의 지진동 제어를 위하여 준능동 감쇠기의 일종인 MR 감쇠기가 적용되고 있다. 본 논문에서는 MR 감쇠기의 위치에 따른 인접 건축물의 지진동 제어성능을 분석하여 MR 감쇠기의 설치에 대한 최적의 위치를 선정하고자 한다. 본 연구를 위하여 인접한 20층과 15층 건축물을 예제 구조물로 사용하였으며 이 예제 구조물은 서로 다른 고유진동수를 갖게 하였으며 예제 구조물의 지진동 제어를 위하여 Groundhook 제어기법을 적용하였다. 예제 구조물의 수치해석에 의한 지진응답 분석결과, 변위응답 제어를 위하여 인접 건축물의 최상층에 MR 감쇠기를 설치하는 것이 제어성능에 있어서 우수하며 가속도응답을 제어하기 위해서는 인접 건축물의 중간층에 MR 감쇠기를 설치하는 것이 우수한 제어성능을 보이고 있다. MR 감쇠기를 중간층에 설치할 경우에, 변위응답과 가속도응답을 동시에 제어가 가능하다. 따라서 건축물의 제어 목표에 따라서 MR 감쇠기 설치위치를 적절하게 선정해야 할 것이다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집A
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• pp.433-439
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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 and small size. To design a MR damper that has a large maximum dissipating torque and a low damping coefficient, 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 trajectories.

• 한국소음진동공학회논문집
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• 제23권5호
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• pp.463-471
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• 2013

This paper presents design and control of electronic control suspension(ECS) equipped with controllable magnetorheological(MR) damper for passenger vehicle. In order to achieve this goal, a cylindrical type MR fluid damper that satisfies design specification of a middle-sized commercial passenger vehicle is proposed. After manufacturing the MR damper with design parameters, their field-dependent damping forces are experimentally evaluated and compared with those of a conventional damper. A quarter-vehicle MR ECS system consisting of sprung mass, spring, tire, controller and the MR damper is established in order to investigate the ride comfort performances. On the basis of the governing equation of motion of the suspension system, five control strategies(soft, hard, comfort, sport and optimal mode) are formulated. The proposed control strategies are then experimentally realized with the quarter-vehicle MR ECS system. Control performances such as vertical acceleration of the car body and tire deflection are evaluated in frequency domains on random road condition. In addition, performance comparison of WRMS(weighted root mean square) of the quarter-vehicle MR ECS system on random road are undertaken in order to investigate ride comfort characteristics.

• 한국산학기술학회논문지
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• 제10권12호
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• pp.3567-3573
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• 2009

본 연구에서는 MR유체를 특징으로 하는 대시포트형 마운트를 제안하고, 자극 형상 및 구조의 변화가 MR유체 마운트의 감쇠력에 미치는 영향에 대하여 실험적으로 고찰하였다. 자극의 유효길이와 코어 중심부의 구조를 달리하여 MR 유체 마운트를 제작하였다. MR유체 마운트에 자기장을 형성하기 위하여 공급하는 전류의 세기를 변화시켰을 때의 감쇠력 변화와 전류를 공급하지 않은 경우의 감쇠력 변화를 측정하였다. 또한, 가진 변위는 일정하게 유지한 상태에서 MR엔진마운트에 가해지는 가진 주파수를 변화시켜 감쇠력의 변화를 측정하였다. MR유체마운트로부터 전달되는 힘은 가진 주파수가 증가함에 따라 감소하는 경향을 나타냈으며, 공급하는 전류의 세기가 증가함에 따라 전달되는 힘은 증가하여 나타났다. 자기장이 형성되는 MR마운트에 유효길이 변화에 대해서는 전달력의 변화가 나타나지 않았다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.1298-1302
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• 2000

Electrorheological(HER) and magnetorheologica(MR) fluids have a unique ability to increase the dynamic yield stress of the fluid substantially when electric or magnetic field is applied. ER and MR fluid-based dampers are typically analyzed using Bingham-plastic shear flow analysis under Quasi-steady fully developed flow conditions. An alternative perspective, supported by measurements reported in the literature, is to allow for post-yield shear thinning and shear thickening. To model these, the constant post-yield plastic viscosity in Bingham model can be replaced with a power-law model dependent on shear strain rate that is known as the Herschel-Bulkley fluid model. The objective of this paper is to predict the damping forces analytically in a typical ER bypass damper for variable electric field, or yield stress using Herschel-Bulkley analysis.

• Smart Structures and Systems
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• 제11권5호
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• pp.435-451
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• 2013

High-rise buildings are a common feature of urban cities around the world. These flexible structures frequently exhibit large vibration due to strong winds and earthquakes. Structural control has been employed as an effective means to mitigate excessive responses; however, structural control mechanisms that can be used in tall buildings are limited primarily to mass and liquid dampers. An attractive alternative can be found in outrigger damping systems, where the bending deformation of the building is transformed into shear deformation across dampers placed between the outrigger and the perimeter columns. The outrigger system provides additional damping that can reduce structural responses, such as the floor displacements and accelerations. This paper investigates the potential of using smart dampers, specifically magnetorheological (MR) fluid dampers, in the outrigger system. First, a high-rise building is modeled to portray the St. Francis Shangri-La Place in Philippines. The optimal performance of the outrigger damping system for mitigation of seismic responses in terms of damper size and location also is subsequently evaluated. The efficacy of the semi-active damped outrigger system is finally verified through numerical simulation.