• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1998.10a
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• pp.156-165
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• 1998

This paper proposes a systematic design methodology for the Takagi-Sugeno(TS) model based fuzzy control system with guaranteed stability and additional constraints on the closed-loop pole location. These combined two objectives are formulated as a system of LMIs(Linear Matrix Inequalities). Since LMIs intrinsically reflect constraints, they tend to offer more flexibility for combining various constraints on the closed-loop system. To demonstrate the usefulness of the proposed design methodology it is applied to the requlation problem of a nonlinear magnetic bearing system. Simulation results show that the proposed LMI-based design methodology yields not only maximized stability boundary but also the desired transient responses.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.449-451
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• 2003

In this paper, the stability problem for singular bilinear system is investigated. We present state feedback control laws for two classes of singular bilinear plants. Asymptotic stability of the closed-loop systems is derived by employing singular Lyapunov's direct method. The primary advantage of our approach lies in its simplicity. In order to verify effectiveness of the results, two numerical examples are given.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.3
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• pp.249-254
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• 2009

This paper studies the problem of pole placement by an LQ controller for system having two distinct real poles. Using the so-called Pole's Moving Range (PMR) drawn in the s-plane and relational equations between closed-loop system poles and weighting matrices, we calculate the state weighting matrix to move two distinct real poles to a pair of complex poles. By numerical examples, we show that the proposed method is applied to improve system performance.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2001.11a
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• pp.181-185
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• 2001

This paper presents a digitally speed sensorless control system for induction motor with direct torque control (DTC). The drive is based on Mode1 Reference Adaptive System (MRAS) using state observer as a reference model fat flux estimation. The system are closed loop stator flux and torque observer for wide speed range that inputs are currents and voltages sensing of motor terminal, model reference adaptive control (MRAS) with rotor flux linkages for the speed turning aignal at low speed range, two hysteresis controllers. The Proposed system is verified through simulation.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.8
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• pp.6-13
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• 2014

In this paper, a multiwavelength-switchable first-order fiber flexible filter is newly proposed, which is based on a polarization-diversity loop. The proposed filter consists of a polarization beam splitter, three half-wave plates(HWPs), and two high birefringent fibers(HBFs). The proposed filter has a good flexibility in adjusting relative angular difference between the principal axes of two HBFs by inserting an HWP between two HBFs. The first-order flat-top or narrow band transmission spectra and the zeroth-order transmission spectra, which had a channel spacing of ~0.8nm, could be obtained by controlling the three HWPs, and, in particular, each of them could also be interleaved. In addition, zeroth-order transmission spectra with a channel spacing of ~0.8nm could be flexibly converted into those with a channel spacing of ~0.4nm through the control of three HWPs, and also be interleaved. The transmission characteristics of the proposed filter was theoretically analyzed and experimentally verified.

• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.6
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• pp.442-450
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• 2020

A small-signal modeling approach for a three-level boost (TLB) converter and a design methodology for a double-loop controller are proposed in this study. Conventional modeling of TLB converters involves three state variables. Moreover, TLB converters have two operation modes depending on the duty ratio. Consequently, complex mathematical calculations are required for controller design. This study proposes a simple system modeling method that uses two state variables, unlike previous methods that require three state variables. Analysis shows that the transfer functions of the two operation modes can be expressed as identical equations. This condition means that the linear feedback controller can be applied to all operational ranges, that is, for full duty ratios. The design method for a double-loop controller using a PI controller is presented in step-by-step sequences. Simulation and experimental verifications are conducted to verify the effectiveness of the small-signal analysis and control system design.

• Structural Engineering and Mechanics
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• v.67 no.6
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• pp.643-658
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• 2018

In this paper, we introduce a new framework for running the finite element (FE) packages inside an online Loop together with MATLAB. Contrary to the Hardware-in-the-Loop techniques (HiL), in the proposed Software-in-the-Loop framework (SiL), the FE package represents a simulation platform replicating the real system which can be out of access due to several strategic reasons, e.g., costs and accessibility. Practically, SiL for sophisticated structural design and multi-physical simulations provides a platform for preliminary tests before prototyping and mass production. This feature may reduce the new product's costs significantly and may add several flexibilities in implementing different instruments with the goal of shortlisting the most cost-effective ones before moving to real-time experiments for the civil and mechanical systems. The proposed SiL interconnection is not limited to ABAQUS as long as the host FE package is capable of executing user-defined commands in FORTRAN language. The focal point of this research is on using the compiled FORTRAN subroutine as a messenger between ABAQUS/CAE kernel and MATLAB Engine. In order to show the generality of the proposed scheme, the limitations of the available SiL schemes in the literature are addressed in this paper. Additionally, all technical details for establishing the connection between FEM and MATLAB are provided for the interested reader. Finally, two numerical sub-problems are defined for offline and online post-processing, i.e., offline optimization and closed-loop system performance analysis in control theory.

• Journal of Advanced Marine Engineering and Technology
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• v.17 no.3
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• pp.60-69
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• 1993

The speed control associated with dc servo motors for direct-drive applications of mobile robot is considered in this study. Robot is moved by power wheeled steering of two dc servo motors mounted to it. In order to cooperate with micro-computer and to achieve the high-performance operation of dc servo motor, speed control system is composed of a digital Phase Locked Loop and H-type drive circuit. And the motor is driven by Pulse Width Modulations. In controlling PWM, it is modified to compose of H-type drive circuit with feedback diodes and switching transistor and design of control sequence so that it may show linear characteristics. As a result, speed characteristics of motor showed linear features. In order to get data on design of PLL control system, the parameters of 80[W[ motor & robot device is measured by simple software control. The PLL speed control system is schemed and designed by leaner drive circuit and measured parameters. A complete speed control system applied to 80[W] dc servo motor showed good linearity, stability and high response. Also, it is verified that the PLL speed control system has good compatibility as a mobile robot driver.

• Journal of Mechanical Science and Technology
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• v.17 no.7
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• pp.978-985
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• 2003

In this paper, a new proportional solenoid invented for pneumatic directional control valves is introduced. The new proportional solenoid has two-dimensional structure and a pivoting armature on which the friction force is inherently negligible. Another advantageous feature of this solenoid is that its mechanical parts can be easily manufactured and assembled. The working principle and design example of the now proportional solenoid, its application to the activation of a 4/3-way directional control valve, and the evaluation of its control performance in a position control loop are reported.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.71.4-71
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• 2001

This paper presents swing up and stabilization control of an underactuated two-link robot called the Pendubot. This device is a two-link planar robot with an actuator at the shoulder, but no actuator at the elbow. The controller swings up first link from its open loop stable equilibrium point to the unstable equilibrium point and then, catches the unactuated second link to balance it there. Two control algorithms are used for this task. Proportional Derivative Control technique is used to design the swing up control. The linear model of Pendubot is obtained by linearizing the nonlinear dynamic equations about the desired equilibrium point and LQR technique is used to design a stabilization controller.