• International Journal of Precision Engineering and Manufacturing
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• v.2 no.2
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• pp.48-56
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• 2001

This paper presents the position tracking control of a closed-loop cylinder system using electro-rheological (ER) valve actuators. After manufacturing three sets of cylindrical ER valves on the basis of Bingham model of ER fluid, a 3 dof(degree-freedom) closed-loop cylinder system having the heave, roll and pitch motions is constructed. The governing equations of motion are derived using Lagrange's equation and a control model is formulated by considering nonlinear characteristics of the system, Sliding mode controllers are the designed for these ER valve actuators in order to achieve position tracking control. The effectiveness of trajectory tracking control performance of the proposed cylinder system is demonstrated through computer simulation and experimental implementation of the sliding mode controller.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.3
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• pp.165-173
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• 2000

This Paper presents the position tracking control of a closed-loop cylinder system using electro-rheological(ER) valve actuators. After manufacturing three sets of cylindrical ER valves on the basis of Bingham model of ER fluid, a 3 dof(degree-of-freedom) closed-loop cylinder system having the heave, roll and pitch motions is constructed. The governing equations of motion are derived using Lagrange's equation and a control model is formulated by considering nonlinear characteristics of the system. Sliding mode controllers are then designed fer these ER valve actuators in order to achieve position tracking control. The effectiveness of trajectory tracking control performance of the proposed cylinder system is demonstrated through computer simulation and experimental implementation of the sliding mode controller.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.10
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• pp.911-917
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• 2000

As many sensors and actuators are used in various automated systems, the application of network to real-time distributed control system is gaining acceptance in many industries. In order to take advantages of networking, however, the network should be carefully designed to satisfy real-time distributed control. This paper presents an implementation method of closed-loop control using Profibus-FMS. In order to implement a closed-loop control system, we used industrial computers with Profibus-FMS network cards and a DC servo motor. Through various experiments, the step response of the control system with network was compared with the reference response without network.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.9 s.90
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• pp.801-810
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• 2004

Parameter modification of a linear finite element model(FEM) based on modal sensitivity matrix is usually performed through an effort to match FEM modal data to experimental ones. However, there are cases where this method can't be applied successfully; lack of reliable modal data and ill-conditioning of the modal sensitivity matrix constitute such cases. In this research, a novel concept of introducing feedback loops to the conventional modal test setup is proposed. This method uses closed-loop natural frequency data for parameter modification to overcome the problems associated with the conventional method based on modal sensitivity matrix. We proposed the whole procedure of parameter modification using the closed-loop natural frequency data including the modal sensitivity modification and controller design method. Proposed controller design method is efficient in changing modes. Numerical simulation of parameter estimation based on time-domain input/output data is provided to demonstrate the estimation performance of the proposed method.

• 제어로봇시스템학회:학술대회논문집
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• 1986.10a
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• pp.86-89
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• 1986

This paper presents a design methodology for a PID regulator. The parameters of the PID regulator are determined through equivalent structure to the closed-loop system whose feedback gain assigns prescribed eigenvalues of the closed-loop system and minimizes a given performance index.

• Journal of Power Electronics
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• v.16 no.3
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• pp.1025-1035
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• 2016

Luenberger observer (LO)-based sensorless multi-loop control of a converter requires an iterative trial-and-error design process, considering that many parameters should be determined, and loop gains are indirectly related to the closed-loop characteristics. Robust H∞ control adopts a compact sensorless controller. The algebraic Riccati equation (ARE)-based and linear matrix inequality (LMI)-based H∞ approaches need an exhaustive procedure, particularly for a low-order controller. Therefore, in this study, a novel robust H∞ synthesis approach is proposed to design a low-order sensorless controller for boost converters, which need not solve any ARE or LMI, and to parameterize the controller by an adjustable parameter behaving like a "knob" on the closed-loop characteristics. Simulation results show the straightforward closed-loop characteristics evaluation and better dynamic performance by the proposed H∞ approach, compared with the LO-based sensorless multi-loop control. Practical experiments on a digital processor confirmed the simulation results.

• Proceedings of the KIEE Conference
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• 1999.11c
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• pp.512-514
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• 1999

The damping ratio $\zeta$ of a continuous 2nd order response which passes all the points of the discrete response of a 2nd order discrete system(envelope curve) is a function of only the location of the closed-loop pole and ie not at all related to the location of the zero. And the peak overshoot of the envelope curve is uniquely specified by the damping ratio $\zeta$, which is a function of solely the closed-loop pole location, and the angle $\alpha$ which is determined by the relative location of the zero with respect to the closed-loop complex pole. Therefore, if the zero slides on the real axis with the closed-loop complex poles being fixed, then the angle $\alpha$ changes however the damping ratio $\zeta$ does not. Accordingly, when the closed-loop system poles are fixed, the peak overshoot is function of $\alpha$ or the system zero. In this thesis the effects of the relative location of the zero on the system performance of a second order discrete system is studied.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1632-1633
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• 2007

This paper presents a new method of designing digital controller based on closed-loop identification of a pulse width modulation (PWM) converter system. We consider the control system structure which is composed of both current control loop and voltage control loop. The current controller can be designed independently of voltage loop. Whereas voltage controller can not do easily due to the PWM switching component which is nonlinear in nature. Furthermore, the control objective of inner loop is to track the sine wave of 60 Hz, but the outer loop shall maintain the constant DC voltage irrespective to load change. To systematically design outer loop controller, we propose a method finding linear approximate model of the nonlinear inner loop part including current controller by closed loop identification. Based on the identified model, we show that a simple digital voltage controller can be directly designed and it has good performance.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1068-1070
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• 2000

This paper presents a method of designing the control loop for dc-to-dc converters when at characteristics of the converter's load are unknown. In the proposed method, a converter is considered as a stand-alone module that feeds a current sink load, and the control loop is designed in order to maximize the robustness of the converter's closed-loop performance. The proposed method yields a control design that provides predictable and controllable closed-loop performance for the converter loaded with an actual load.

• Proceedings of the KIEE Conference
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• 1999.11c
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• pp.552-554
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• 1999

In this paper, a robust control system with the disturbance observer is proposed for BLDC servo system. The overall control system consists of the speed controller which is implemented with PI controller and the disturbance observer with free parameters. The proposed control system is designed the command input response and the closed loop characteristics independently by using two-degrees-of-freedom concept, so it can improve the closed loop characteristics with no influence on the command input response. The effective suppression of disturbance with the observer improves the characteristics of the closed loop of the system. And also, by fluting the bandwidth of free parameters, measurement noise is considered. To verify the better performance of the proposed control system than that of the conventional PI controllers, the performance of the controller is analyzed theoretically and some simulation results are presented.