• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2003.11a
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• pp.229-234
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• 2003

As electrorheological fluid(ER fluid) has a characteristic that apparent viscosity varies when electric field applied, so rheological characteristic(yield stress & viscosity) changes in proportion to the electric field applied and the response time is very short within a few miliseconds . In case of using ER fluid for journal bearing as lubricant, it is estimated that it's possible to realize very effective journal bearing system that is not complicate and has a very quick response time. It is necessary to examine the influence of rheological characteristic that varies with electric field applied on bearing characteristic to apply ER fluid to journal bearing, however there are few studies for about that. As for the journal bearing, it comes under high shear flow mode that has shear rate range of $10^3\~10^4s^{-1}$ because rotational speed is very high and clearance is small. But most of the studies for about ER fluid issued until now is about the range of $10\~10^2s^{-1}$. So, there are a lot of difficulties to understand the characteristic offish shear flow mode and furthermore it is restricted to make an experiment for about the characteristic of ER fluid because of the limitation of experimental equipment. The equipment was prepared to make an experiment lot high shear flow mode that has the range of $10^3\~10^4s^{-1}$ using ER fluid that is composed of silicon oil with dispersed particle of starch. Using the above system, the fluid characteristic of ER fluid was studied.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.10a
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• pp.451-455
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• 1997

This paper presents vibration mode control of a smart plate containing electro-rheological (ER) fluid between elastic face layers. Following the composition of a silicone oil-based ER fluid, the ER fluid-embedded plate partitioned into four sections is constructed. Then, an extensive modal test is experimentally carried out to identify field-dependent modal parameters such as mode shapes and natural frequencies of the structure with respect to different are subjected to electric fields. The distilled results from the experiment exhibit that the ER fluid can be effectively employed in a continuous fashion to tune modal behaviors of the distributed parameter systems,

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.357-360
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• 1997

This paper presents a new anti-lock brake system(ABS) using electro-rheological(ER) valve actuators for the wheel slip control. The hydraulic dynamic model of the automotive brake system is formulated by incorporating electric field-dependent Bingham properties of ER fluid obtained experimentally. The brake system designed by this hydraulic model is able to control wheel slip by controlling the intensity of electric field which tunes the braking torque. The control fields of the ER valve to command desired wheel slip are determined by a sliding mode controller. A comparison between the proposed brake system and the conventional brake system is made by providing with computer simulations of vehicle motions under ABS performance requirement condition.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.4
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• pp.400-408
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• 2009

This work presents experimental results on vibration control of flexible structures using the squeeze mode electrorheological(ER) mount. An appropriate size of the squeeze mode ER mount is devised and its field-dependent damping force characteristics are experimentally evaluated. The ER mount is then applied to two different flexible structures : beam structure and frame structure. An optimal controller associated with displacement and acceleration signals is designed to suppress the imposed vibration and experimentally realized using the microprocessor. Vibration control responses of the flexible structures such as acceleration are evaluated in time and frequency domains.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.3
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• pp.284-290
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• 2012

In this research, a new type of haptic master device using electrorheological(ER) fluid for minimally invasive surgery(MIS) is devised and control performance of the proposed haptic master is evaluated. The proposed haptic master consists of ER bi-directional clutch/brake for 2 DOF rotational motion(X, Y) using gimbal structure and ER brake on the gripper for 1 DOF rotational motion (Z). Using Bingham characteristic of ER fluid and geometrical constraints, principal design variables of the haptic master are determined. Then, the generation of torque of the proposed master is experimentally evaluated as a function of applied field of voltage. A sliding mode controller which is robust to uncertainties is then designed and empirically realized. It has been demonstrated via experiment that the proposed haptic master associated with the controller can be effectively applied to MIS in real field conditions.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.23 no.6 s.165
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• pp.1055-1064
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• 1999

In this wort ER(electro-rheological) clutch and MR(magneto-rheological) clutch are devised and their performance characteristics such as response time and controllability are compared. As a first step, field-dependent yield stresses of ER and MR fluids are distilled in shear mode. For reasonable comparison between two clutches, a nondimensional design model is established by choosing same design parameters of gap size and number. Following the manufacturing of two clutches, field-dependent torque level, response time to step input, mechanical Power generation to electric power consumption are experimentally measured and compared. In addition, in order to investigate torque controllability of the clutches a sliding mode controller is formulated and experimentally realized. Control bandwidths of two clutches are identified and tracking control responses for desired torque trajectories are presented.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.5
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• pp.24-29
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• 2004

This paper presents the tension control of a wire-cut discharge machine using electrorheological(E,R) fluid based brake system. On the basis of the tension level required in the machine, an appropriate size of the ER brake which features design simplicity, fast response and salient controllability is designed. Considering the Bingham property of ER fluid and actuator response time, the governing equation of the ER brake is derived. And a tension propagation of wire electrode is modeled via frequency response. The tension control performance of the discharge machine is simulated by using a robust sliding mode controller.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.8
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• pp.102-111
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• 1996

This paper presents a proof-of-concept investigation on an active tension control using an ER (electro-rheological) brake actuator. Firstly, an ERF (electro-rheological fluid) which has an inherent reversible feature from Newtonian fluid to Bingham fluid upon applying an electric field is composed, and its property is tested to obtain intrinsic parameters of the Bingham model. An appropriate size of the ER brake is manufactured on the basis of the Bingham model, and dynamic characteristics of the brake are experimentally identified. After formulating a governing equation of motion of the tension control system, a sliding mode controller is designed to achieve a certain desired level of tension. Both simulation and experimental works are undertaken in order to demonstrate the efficiency and feasibility of the proposed active tension control method.

• ETRI Journal
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• v.27 no.1
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• pp.95-101
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• 2005

Waveguide structures of the stand-alone electroabsorption (EA) modulator and the electroabsorption modulated laser (EML) are investigated using the 3D beam propagation method. The EA waveguide structures with InP-based passivation layers show saturation in the extinction ratio (ER) due to the stray light traveling through the passivation layers. This paper demonstrates that narrower passivation layers suppress stray-light excitation in the EA waveguide, increasing the ER. A taper structure in the isolation section of the EML waveguide can reduce the mode mismatch and suppress the excitation of the stray light, increasing the ER further. Low-index-polymer passivation layers can confine the mode more tightly in the active waveguide, yielding an even higher ER.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.04a
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• pp.394-399
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• 1997

This paper presents a new concept of a semi-active suspension system for a commercial vehicle seat. The proposed suspension system features an ER(electro-rheological) damper which can produce continuously tunable damping forces by control electric fields. A dynamic model of the ER damper is first achieved by incorporating Bingham property of the ER fluid, followed by the formulation of governing equations of motion for the suspension system. A sliding mode controller is then designed on the basis of the hyper-plane sliding mode scheme. The effectiveness of the proposed control system is evaluated by investigating control performance for vibration isolation.