• The Transactions of the Korean Institute of Electrical Engineers D
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• v.50 no.8
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• pp.376-383
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• 2001

Factors leading to poor control of the steam generator in a nuclear power plant are nonminimum phase characteristics, unreliable of flow measurements and nonlinear characteristics, which increase more at low power(below 20%) operation. And the study of problems for water level control in the steam generator is that design water level controller only power renge, not entire. This paper introduces a model predictive control(MPC) algorithm for solving poor control factors and quadratic programming(QP) for solving input constraints. Also presents the design method of stable model predictive controller in the entire power range. The simulation results show the efficiency of proposed MPC controller by comparing with PI controller, and effect of the design parameters.

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.6
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• pp.176-187
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• 1995

The problem of designing intelligent cruise control system for a longitudinal motion of an automobile, which is powered by internal combustion engines coupled to an automatic multispeed transmission, is considered. The basic concept is a vehicle-following system which maintains desired spacing between vehicles. This system actuates throttle with the information of the spacing error so as to maintain proper spacing and improve passenger ride comfort. In designing the controller, a modified controller, i.e, PID gain scheduling and fuzzy controller with fuzzy compensator was developed in order to overcome the nonlinearities of the automobile and obtain better performance. The computer simulation results illustrate that the better vehicle responses were obtained with the modified fuzzy controller and, under this controller, the vehicle responses were found to be relatively insensitive to parameter variations.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.22 no.50
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• pp.127-137
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• 1999

This study is concerned with the loading problems in flexible manufacturing system(FMS). The loading problem in FMS is a complex one, when the number of machine and job is increased. It may be time-consuming and even impossible to achieve an optimal solution about this problem mathematically. Thus, a heuristic method is recommended in order to gain near-optimal solutions in a practically acceptable time. A new loading algorithm is developed with a multi-criterion objective of considering the workload unbalance, and maximizing the machine utilization, throughput for critical resources such as the number of tool slots and the number of working hours in a scheduling period and so on. The results of SAS analysis indicated that true average throughput of proposed heuristic loading statistically exceeds that of Shanker and Srinivasulus loading algorithm at the significance level of 0.1.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.7
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• pp.582-588
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• 2001

The Multiple Model/Controller IMC(MMC-IMC) is a model-based control method which uses a set of model/controller pairs rather than a single model/controller to handle all possible operating conditions in the IMC control structure. During operation, one model/controller pair that best fit, for current plant situation is chosen by the switching algorithm. The major drawback of the switching controller is the bad transient performance due to the model error and the use fo linear controller for nonlinear plants. In this paper, we propose a method that transient response of the MMC-IMC using two recurrent neural networks. Simulation result shows that the proposed method represents better performance than the usual MMC-IMC`s.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.7
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• pp.589-596
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• 2001

In this paper, a new design methodology for the optimal control of nonlinear systems described by the TS(Takagi-Sugeno) fuzzy model is proposed. First, a new theorem concerning the optimal stabilizing control of a general nonlinear dynamic system is proposed. Next, based on the proposed theorem and the inverse optimal approach, an optimal controller synthesis procedure for a TS fuzzy system is given, Also, it is shown that the optimal controller can be found by solving a linear matrix inequality problem. Finally, the proposed method is applied to the attitude control of a rigid spacecraft to demonstrate its validity.

• Proceedings of the KIEE Conference
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• 1999.07a
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• pp.101-104
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• 1999

This paper presents the design of state feedback controller with state observer(dynamic filter) for Electro-Magnetic Suspension System. Also, the gain scheduling technique using state observer is analyzed in the time domain and frequency domain.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.7
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• pp.1309-1313
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• 2010

In this paper, we propose a novel guidance law for controlling an UAV(Unmanned Air-Vehicle) to follow a reference line in vertical plane. A kinematics model representing the relative motion of the UAV to the reference line is derived. And then LQR(Linear Quadratic Regulator) theory is applied to the model to derive the VLFG(Vertical Line Following Guidance) law. The resultant guidance law forms a gain-scheduling controller scheduled by a simple parameter $\sigma$ which is a function of the UAV's velocity, axial acceleration, gravity, and the slope of the reference line. Also derived is a stability condition for the $\sigma$ variation based on Lyapunov theory. Simulation results show that the proposed guidance law can be applied effectively to UAV guidance algorithm design.

• Proceedings of the KIEE Conference
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• 1998.11b
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• pp.689-692
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• 1998

In this research a fault-tolerant and bumpless switching control is proposed for boiler systems used in the power plants. Firstly, three operating points are selected to control the nonlinear boiler through the full operational range, and the $H_{\infty}$ loop shaping controller and the model-based predictive controller(MBPC) are designed. To prevent the windup and bump problems which are caused by the actuator saturation and the controller switching, an anti-windup and bump less transfer technique is adopted to the $H_{\infty}$ loop shaping controller. Also the constrained gain-scheduling technique is applied to MBPC to achieve the same objective. Secondly, the fault-tolerant control technique is proposed to continue the control action without stopping the boiler operation even in case of some faults. Through various simulation studies, the performances of the proposed control techniques are demonstrated.

• Journal of Advanced Marine Engineering and Technology
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• v.24 no.4
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• pp.435-440
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• 2000

The speed control system of diesel engine is considerably nonlinear. Therefore, a countermeasure such as gain scheduling used to be incorporated to compensate this nonlinearity. On the other hand, it is said that fuzzy control is very robust against nonlinearity. But it is difficult to get a satisfactory response with only fuzzy control in real system. In this paper authors design a fuzzy-PI controller for the speed control of Medium diesel engine and carry out experiments with dedicate system implemented by Intel 80916KC to real diesel engine, Deawoo MAN 6Cyl., 1800rpm driving 3$\psi$220V, 150KW generator. We confirm the effectiveness of proposed control system.

• 제어로봇시스템학회:학술대회논문집
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• 1998.10a
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• pp.205-209
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• 1998

A synthesis of fuzzy variable structure control is proposed to design a high-angle-of-attack flight system for a modification version of the F-18 aircraft. The knowledge of the proportional, integral, and derivative control is combined into the fuzzy control that addresses both the highly nonlinear aerodynamic characteristics of elevators and the control limit of thrust vectoring nozzles. A simple gain scheduling method with multi-layered fuzzy rules is adopted to obtain an appropriate blend of elevator and thrust vectoring commands in the wide operating range. Improving the computational efficiency, an accelerated kernel for on-line fuzzy reasoning is also proposed. The resulting control system achieves the good flying quantities during a high-angle-of- attack excursion. Thus the fuzzy logic can afford the control engineer a flexible means of deriving effective control laws in the nonlinear flight regime.