• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.3
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• pp.278-285
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• 1999

This paper utilizes the method of Q-parameterization control to design a controller which solves the problem of imbalance in magnetic bearing systems. There are two methods to solve this problem using feedback controal. The first method is to compensate for the imbalance forces by generating opposing forces on the bearing surface (imbalance compensation). The second method is to make the rotor rotate around its axis of inertia (automatic balancing);in this case no imbalance forces will be generated. In this paper we deal with only imbalance compensation. The free parameter of the Q-parameterization controller is chosen such that these goals are achieved. After the introduction of a model of the magnetic bearing system, we explain the Q-parameterization controller design of the magnetic bearing system with emphasis on the rejection of sinusoidal disturbance for imbalance compensation design. The design objectives are formulated as a linear equations in the controller free paramete Q. Finally, simulation and experimental results are presented and showed the robustness and effectiveness of the proposed controllers.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10a
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• pp.52-55
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• 1996

In this paper, we consider the decentralized reduced-order H$_{\infty}$ controller for the general plant. Simplifying method is suggested for the general plant with the decentralized controller structure. When the controller is reconstructed for the original system, the decentralizability of the controller for the transformed system is generally destroyed with the older method. We solve this problem. For the simplified system, the structure of the decentralized controller is suggested..

• Proceedings of the KIEE Conference
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• 1997.07b
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• pp.636-638
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• 1997

This paper deals with the problem of finding robust controller based upon a pole assignment method for a plant with parameter perturbations. This case is not a problem of Interval polynomial family but a problem of poly topic polynomial family. As a method of stability test, we used GKT(Generalized Kharitonov Theorem) having computational advantage.

• Proceedings of the KIEE Conference
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• 1999.11c
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• pp.555-557
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• 1999

This paper implements an active noise controller in a headset by solving Robust $H_{\infty}$ control problem. In the $H_{\infty}$ control framework, we can suppose the noise in a headset as disturbance and the noise control problem is cast on the well-known $H_{\infty}$ regulation problem. By representing the system as LFT(Linear Fractional Transformaion) form, the controller is obtained using D-K iteraitons. The designed controller was implemented with operational amplifiers and it produced the desired noise reduction performance.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.975-980
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• 2004

Positioning system is widely used for many practical applications. This system requires a good controller to achieve high accuracy and fast response with simple and self-adjustable design. In order to satisfy the above requirements, a new practical controller for positioning systems, namely nominal characteristic trajectory following (NCTF) controller with PI compensator, has been proposed. However, the effect of actuator saturation can not be completely compensated for integrator windup when the object parameters vary. This paper presents a method to improve the NCTF controller by overcoming the problem of integrator windup by adopting a fuzzy system. The improvement of the NCTF controller is evaluated through simulation using a rotary positioning system. The simulation result has demonstrated the effectiveness of the compensated NCTF in overcoming the problem of integrator windup.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.5
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• pp.44-51
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• 2008

In this paper, the optimal tuning of a cross-coupled controller linked with the feedforward controller is studied to reduce contouring and tracking errors of a bi-axial servomechanisms by using the previously developed integrated tuning method. The CCC system for an arbitrary curve, which is combined with the feedforward controller, is formulated by a state-space based on a series of linear motion trajectories. An optimal tuning problem is formulated as a nonlinear constrained optimization problem including relevant controller parameters of the servo. To verify the effectiveness of the proposed optimal tuning procedure, linear and circular motion experiments are performed on the xy-table. Experimental results confirm that both tracking and contouring errors are significantly reduced by applying the proposed control and tuning system.

• Computers and Concrete
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• v.30 no.5
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• pp.357-367
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• 2022

In this paper, we propose an efficient control method that can be transformed into a general building control problem for building structure control using these reliability criteria. To facilitate the calculation of controller H∞, an efficient solution method based on Linear Matrix Inequality (LMI) is introduced, namely H∞-based LMI control. In addition, a self-tuning predictive grey fuzzy controller is proposed to solve the problem caused by wrong parameter selection to eliminates the effect of dynamic coupling between degrees of freedom (DOF) in Self-Tuning Fuzzy Controllers. We prove stability using Lyapunov's stability theorem. To check the applicability of the proposed method, the proposed controller is applied and the control characteristics are determined. The simulation assumes system uncertainty in the controller design and emphasizes the use of acceleration feedback as a practical consideration. Simulation results show that the performance of the proposed controller is impressive, stable, and consistent with the performance of LMI-based methods. Therefore, an effective control method is suitable for seismic reinforcement of civil buildings.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.36 no.5
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• pp.360-366
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• 1987

The design problem of optimal constant PIDM (proportional-integral-derivative and measurable variable) feedback controller for linear time-invariannt systems is investigated with the time-weighted quadratic performance index. Necessary conditions for an optimality of the controller are derived and an algorithm for computing the optimal feedback gain is presented. It is shown via example that the design mithod using the time-weighted quadratic performance index improves the transient responses of the closed-loop system.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.151.2-151
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• 2001

In this paper, the design of a two-degree-of-freedom(TDF) controller is proposed to track the reference model, as well as to reject an influence of measurable disturbance for descrpitor system. The TDF controllers based on the Youla parametrization reveals that the design of the feedforward controller and the regulator can be done independently. First, to solve this problem, we will change descriptor system into regular state space system using a state feedback. And then, the feedforward controller is determined by solving a full information approach for augmented system with a nominal control constraint, and the regulator is designed by means of the loop-Shaping method.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.292-292
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• 2000

Since high-power CO$_2$ Laser can be make a high densed energy to Local processing area, manufacturing processes using the laser can be processed for very Localized areas at a very fast rate with minimal or no distortion. Accordingly, the laser has been widely used in the fields of thermal manufacturing processes such as welding, fusion cutting, grooving, and heat treatment of metals. In particular, interest in the laser heat treatment process has grown tremendously in the past few years. In this process, maintaining the uniform hardening depth is important problem to obtain good quality products and to reduce heat induced distortion and residual stress. For achieving this objective, we introduced a new design technique of a fuzzy logic controller that greatly simplified the design procedure by defining several simplified design parameters. In the design procedure, the major design parameters of the controller are characterized by identifying several common aspects. From a series of simulation results, we found that the proposed design technique can be effectively used to design of a fuzzy logic controller for the LASER surface hardening process.