• The Transactions of the Korean Institute of Electrical Engineers D
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• v.49 no.9
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• pp.495-503
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• 2000

In this paper we propose a design procedure of loop-shaping two-degree-of-freedom H$\infty$ digital controller for sampled-data system. We extend the continuous time loop-shaping two-degree-of-freedom H$\infty$ control problem to sampled-data system. The configuration of generalized plant is modified for sampled-data system. And then using continuous lifting we obtain the digital controller. In the final stage of loop-shaping procedure the problem of absorbing weighting functions is discussed. We summarize this study to the design procedure and illustrate the application for an inverted pendulum on the cart.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.1
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• pp.1-8
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• 2017

The optimal gain design method of a three-phase boost converter is proposed in this study. The control system has a two-loop configuration, in which each controller is coupled closely; thus, the optimal design is difficult to achieve using conventional gain-tuning method. The proposed method is adopted to the MATLAB SISO TOOL software and is based on the controller requirements, which are phase margin and cut-off frequency of the open-loop system. The optimal proportional -integral gains can be designed easily using the proposed interactive method of the SISO TOOL. The performance of the proposed system is verified through simulation and experiments.

• Proceedings of the KIEE Conference
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• 1999.07b
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• pp.537-539
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• 1999

When dealing with a controller design in the two parameter configuration, there are some situations when neither a known pseudo inverse technique nor the inverse method can be applicable. In this case, we propose two methods of designing a controller by the gradient algorithm and the new pseudo inverse method such that the designed closed loop polynomial may be equal to or nearly equal to the desired closed loop polynomial. We compare the proposed methods with the known methods. We use the Manabe standard form as a desired closed loop characteristic polynomial.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.982-986
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• 1998

The peak-power-tracking solar array regulator sensing the inductor current is proposed. Since it uses the inductor current as the solar array output power information, the PPT control scheme can be greatly simplified. The charge controlled two-loop scheme is presented to improve the dynamics due to the inductor current sensing. The comparison between the single-voltage loop controlled system and the two-loop controlled system employing the charge control is presented. This paper also contains the simulation results of that comparison.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.804-807
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• 1996

In this paper, a new model of TDF(two degree of freedom) spin-stabilized platform has been suggested. The platform driving signal modulated in the spinning frequency is described in demodulated form keeping its precession angular velocity. When a strong spinning torque exists, the cross-axis spring constant cannot be neglected in modelling of the platform precession dynamics. A linearized dynamic model of spin-stabilized platform pointing loop is derived and validated through the comparison between simulation and experimental results.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.12
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• pp.1152-1159
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• 2015

Switching power supply systems are widely used in many industrial fields. Power factor correction (PFC) circuits have a tendency to be applied in new power supply designs. The PFC circuit with a boost converter using an input power source is studied in this paper. In a boost PFC circuit, there are two feedback control loops: a current feedback loop and a voltage feedback loop. In this paper, the regulation performance gained by using the output voltage and compensator to improve the transient response presented at the continuous conduction mode (CCM) of the boost PFC circuit is analyzed. The validity of the designed boost PFC circuit is confirmed by both MATLAB simulation and experimental results.

• Proceedings of the KIEE Conference
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• 2002.11c
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• pp.134-137
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• 2002

This paper presents a robot manipulator kinematic motion control scheme based on velocity feedback loop. The desired joint velocity is obtained by the feature-based visual servoing and is used in the joint velocity control loop system for trajectory control of the robot manipulator. The asymptotic stability of the closed loop system is shown by the Lyapunov method. Effectiveness of the proposed method is shown by simulation and experimental results on a robot manipulator with two degree of freedom.

• Journal of Animal Science and Technology
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• v.58 no.3
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• pp.13.1-13.7
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• 2016

Background: In the present study, various freezing containers were tested for mouse embryos of respective developmental stages; embryos were vitrified and then their survival rate and developmental rate were monitored. Mouse two cell, 8 cell, and blastula stage embryos underwent vitrification freezing-thawing and then their recovery rate, survival rate, development rate, and hatching rate were investigated. Methods: EM-grid, OPS, and cryo-loop were utilized for vitrification freezing-thawing of mouse embryos. Results: It was found that recovery rate and survival rate were higher in the group of cryo-loop compared to those of EM-grid (p < 0.05). Embryonic development rate, two cell embryos to blastocyst, as well as hatching rate were higher in the control group compared to the EM-grid group and OPS group (p < 0.05), yet no difference was noted between the control group and cryo-loop group. Development rate and hatching rate of eight cell morulae and blastocysts were all lower in the treatment groups than the control group whilst hatching rate of blastocysts was higher in the control group compared to the groups of EM-grid and OPS (p < 0.05); although the cryo-loop group was shown to be slightly higher than other groups, it was not statistically significant. Conclusions: In the study, we investigate effects of freezing containers on vitrified embryos of respective developmental stages; it was demonstrated that higher developmental rate was shown in more progressed (or developed) embryos with more blastomeres. There was however, no difference in embryonic development rate was shown amongst containers. Taken together, further additional studies are warranted with regards to 1) manipulation techniques of embryos for various vitrification freezing containers and 2) preventive measures against contamination via liquid nitrogen.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.407-412
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• 2004

This paper presents a new algorithm for the closed-loop $H_{\infty}$ composite control of singularly perturbed nonlinear systems with a exogenous disturbance, using the successive Galerkin approximation(SGA). The singularly perturbed nonlinear system is decomposed into two subsystems of a slow-time scale and a fast-time scale via singular perturbation theory, and two $H_{\infty}$ control laws are obtained to each subsystem by using the SGA method. The composite control law that consists of two $H_{\infty}$ control laws of each subsystem is designed. One of the purposes of this paper is to design the closed-loop $H_{\infty}$ composite control law for the singularly perturbed nonlinear systems via the SGA method. The other is to reduce the computational complexity when the SGA method is applied to the high order systems.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.7
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• pp.619-624
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• 2011

This paper presents a controller design method for a robust control problem with multiple constraints using genetic algorithms and LMI design method. A robust $H_{\infty}$ constraint with loop shaping and pole placement is used to address disturbance attenuation with error limits and desired transient specifications, in spite of the plant uncertainties and disturbances. In addition, a loop gain constraint is considered so as not to enlarge the loop gain unnecessarily. The robust $H_{\infty}$ constraint and pole placement constraint can be expressed in terms of two matrix inequalities and the loop gain constraint can be considered as an objective function so that genetic algorithms can be applied. Accordingly, a robust controller can be obtained by integrating genetic algorithms with LMI approach. The proposed controller design method is applied to a track-following system of an optical disk drive and is evaluated through simulation results.