• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2005.03a
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• pp.505-512
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• 2005

MR damper is one of the most promising control devices for civil engineering applications to earthquake hazard mitigation. However, a control system including a power supply, controller, and sensors is required to maximize the performance of the MR damper and this complicated control system is not effective to most of large civil structures. This paper proposes and experimentally verified a smart passive damping system using MR(Magnetorheological) dampers by introducing electromagnetic induction(EMI) system as an external power source to MR damper. It is easy to build up and maintain EMI system, because it does not require any control system such as a power supply, controller, and sensors. Numerical simulations using experimental model of EMI system are carried to verify the effectiveness of the proposed EMI system. The performances of smart passive damping system are compared with those of passive and semiactive MR dampers.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.251-256
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• 2000

This paper presents dynamic modeling and controller design of a tracked vehicle installed with the double-rod type ERSU(electro-rheological suspension unit). A 16 DOF(degree-of-freedom) model for the tracked vehicle is established by Lagrangian method. After showing the spring and damping characteristics of the proposed ERSU, equivalent 2 DOF 1/12 tracked vehicle model is then formulated by regarding the spring and viscous damping coefficients under the static state as constant values. A robust LSDP(loop-shaping design procedure) $H_{\infty}$ controller compensating spring and damping parameter variations is then designed in order to suppress unwanted vibration of the vehicle. The control responses such as vertical and pitch acceleration are presented in time domain.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.337-343
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• 2012

NREL(National Renewable Energy Laboratory) Baseline controller conduct using method proposed RISO National Laboratory in Region 3. which designed the blade-pitch control system using a single degree-of-freedom model of the wind turbine. Idealized PID-Controlled rotor-speed error will respond as a second-order system with the natural frequency and damping ratio. RISO proposed specific natural frequency(=0.6 rad/s) and damping ratio(=0.7). If specific Eigen value apply to NREL 5 MW wind turbine, differ with pitch respond for simulation results of RISO report. Variation of specific eigen value investigate performance of NREL 5 MW wind turbine.

• Proceedings of the KIEE Conference
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• 2001.07a
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• pp.149-151
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• 2001

This paper proposes the design of STATCOM(static synchronous compensator) stabilizer for improving power system stability using fuzzy logic controller(FLC). The STATCOM DC voltage regulator contributes negative damping to the power system as the installation of STATCOM DC voltage regulator. STATCOM stabiliser is superimposed on the AC voltage regulator to compensate the negative damping effect. To evaluate usefulness of the proposed method, we perform the nonlinear simulation on a single-machine infinite bus system. As results of the simulations, the proposed method shows better control performance than PI controller in terms of damping effects.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.8
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• pp.2501-2507
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• 1996

In this paper actively controlled air bearing is investigated to overcome the defects of air bearing such as low stiffness and damping coefficients. The actively controlled air beairng is composed of an air bearing, a gap sensor, a controller, and a piezo actuator. By controlling the position of air bearing with piezo actuator, the position of floating object is controlled. In this study the proportional-Integral-Derivative controller is employed. Active air bearing is investigated numerically and experimentally. There is good agreement between the simulation and the experimental results. It is shown that the stiffness and damping characteristics and positioning experimental results. It is shown that the stiffness and damping characteristics and positioning accuracy of air bearing can be improved by means of adopting actively controlled air bearing.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1126-1131
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• 2007

This paper presents unified chassis control (UCC) to improve the vehicle lateral stability. The unified chassis control implies combined control of active front steering (AFS), electronic stability control (ESC) and continuous damping control (CDC). A direct yaw moment controller based on a 2-D bicycle model is designed by using sliding mode control law. A direct roll moment controller based on a 2-D roll model is designed. The computed direct yaw moment and the direct roll moment are generated by AFS, ESP and CDC control modules respectively. A control authority of the AFS and the ESC is determined by tire slip angle. Computer simulation is conducted to evaluate the proposed integrated chassis controller by using the Matlab, simulink and the validated vehicle simulator. From the simulation results, it is shown that the proposed unified chassis control can provide with improved performance over the modular chassis control.

• Proceedings of the KIEE Conference
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• 1999.07c
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• pp.1032-1034
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• 1999

The design of an $H{\infty}$ controller for a TCSC to enhance the damping of an inter-area oscillation in a Power system is presented. The paper describes a comprehensive and systematic way of applying the $H{\infty}$ control design algorithm in power systems. Eigen sensitivity analysis to selction a TCSC location is described. Time simulation and eigenvalue analysis show that the proposed TCSC $H{\infty}$ controller can suppress the inter-area oscillations efficiently with robustness.

• Proceedings of the KIEE Conference
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• 1992.07a
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• pp.391-393
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• 1992

This paper proposes an adaptive control system using a 80286 microprocessor-based system and DC servo motors for the control of flexible joint manipulator. In this paper, we construct the controller based on a singular perturbation strategy damping out the elastic oscillations at the joints. we added to the controller the compensator for damping the joint and the term for decreasing the position error between the actuator and the link in order to improve the asymptotical convergence of the position of the link. It is shown that the implementation of this control algorithm can be practical.

• 제어로봇시스템학회:학술대회논문집
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• 1999.10a
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• pp.17-20
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• 1999

In this paper, we consider on hard contact transition control strategies. Hard contact transition phase can be divided into two definitely different phases,“Pre-Transition Phase”and“Transition Phase”. Here we focus on the“Pre-Transition Phase”and we propose three control methods. First, we propose a novel con-troller named as “Suppression Controller”which is not only stable but also simple to implement. Second, we present passive damper named as“Flexible-Damped Joint”Which is good solution in Circumventing pre-transition Phase. Third, We suggest a stable and simple controller which can maximize joint damping and minimize recontact velocity in flexible-damped joint. It is named as“Joint Damping Controller”.

• Journal of Power Electronics
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• v.11 no.4
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• pp.599-605
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• 2011

This paper proposes a gain scheduling method that improves the stability of grid-connected systems employing an LCL-filter. The method adjusts the current controller gain through an estimation of the grid impedance in order to reduce the resonance that occurs when using an LCL-filter to reduce switching harmonics. An LCL-filter typically has a frequency spectrum with a resonance peak. A change of the grid-impedance results in a change to the resonant frequency. Therefore an LCL-filter needs a damping method that is applicable when changing the grid impedance for stable system control. The proposed method instantaneously estimates the grid impedance and observes the resonant frequency at the same time. Consequently, the proposed method adjusts the current controller gain using a gain scheduling method in order to guarantee current controller stability when a change in the resonant frequency occurs. The effectiveness of the proposed method has been verified by simulations and experimental results.