• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.2756-2759
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• 2000

In this paper. A PID motion controller based on the fuzzy concept is discussed for nonholonomic mobile robot. The difficulties in controlling such a Mobile robot vehicle lies in the fact that it usually has only two degrees of freedom for motion control in a tracking mode. It makes the control of speed and steering possible to decompose the error between the reference posture and the current posture. The Gyro compass is used to measure the position of robot. The proposed nonholonomic mobile robot is shown to follow the reference trajectory and compensate the dynamics. Simulation results are provided to validate the proposed controller. Experiments have been used to verify the effectiveness and robustness of the motion controller.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.52 no.7
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• pp.385-392
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• 2003

A nonlinear speed controller for a separately excited DC motor (SEDCM) based on a newly developed adaptive backstepping approach is presented. To compensate parameter uncertainties and load torque disturbance, a nonlinear adaptive backstepping control law and adaptive law are derived systematically step by step through virtual control input and suitable Lyapunov function. Also, speed observer without using costly speed sensor is presented. Simulation results show that the proposed controller can observe real speed and track the reference speed signal generated by a reference model.

• Proceedings of the KIEE Conference
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• 1998.11b
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• pp.526-529
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• 1998

In this paper, we proposed a nonlinear sliding mode controller to regulate the swinging angle of Overhead Crane System. Roughly speaking, the controller is designed to regulate an output(the swing angle) while providing internal stability. It is difficult to apply many of standard nonlinear control design techniques. In contrast to control that use a command generator and possibly a time-varying feedback, our control law is simple autonomous nonlinear controller. We analyze the stability of the closed-loop system using an $L_2$ Sliding surface conditions approach on a nonlinear feedback linearization of the system about the desired periodic orbit. One can easily extend this approach to analyze the robustness of the control system with respect to disturbances and parameter variations.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1726-1727
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• 2007

In this paper, a systematic guideline is introduced to design a stable adaptive fuzzy wavelet controller with sliding mode for a class of uncertain nonlinear systems. Based on the Lyapunov synthesis approach, we construct the fuzzy wavelet controller such that it can basically control and guarantee the stability of the whole control system. On the other hand, a robust controller is design to restrain or eliminate the disturbance and assure the desired output accuracy of a control system. Some experimental results for a chaotic system are provided here to demonstrate the effectiveness of the control algorithm.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.585-588
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• 1997

This paper presents a construction method of logic-based switching control system which operates in widely changing environments. The logic-based switching controller is composed of a family of candidate controllers together with a supervisor. The system does not require any identification schemes of environments. Switching from one candidate controller to another is carried out based on monitoring the output of the system. The basic ideas of adaptation are as follows: (1)each candidate controller is prepared for each environment in advance; (2)the supervisor applies a sequence of speculative controls to a plant with candidate controllers just after the control has started and just after the change of the environment has been detected. It is important that each candidate controller can keep the system stable during a sequence of speculative controls, and the most appropriate candidate controller for the environment to which the system is exposed can be selected before the last speculative control is ended. An application to an antiskid braking system clarifies the effectiveness of the proposed method.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1109-1114
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• 2007

This paper presents the road simulator control technology for reproducing the road input signal to implement the real road data. The simulator consists of the hydraulic pump, servo valve, hydraulic actuator and its control equipment. The QFT is utilized to control the simulator effectively. The control system illustrates a tracking performance of the closed-loop controller with low order transfer function G(s) and pre-filter F(s) for a parametric uncertain model. A force controller is designed to communicate the control signal between simulator and digital controller. The efficacy of the QFT force controller is verified through the numerical simulation, in which combined dynamics and actuation of the hydraulic servo system are tested. The simulation results show that the proposed control technique works well under uncertain hydraulic plant system. The conventional software (Labview) is used to make up for the real controller in the real-time basis, and the experimental works show that the proposed algorithm works well for a single road simulator.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.53 no.3
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• pp.122-128
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• 2004

This paper presents a control approach for designing a fuzzy-PI controller for a synchronous generator excitation and SVC system. A combination of thyristor-controlled reactors and fixed capacitors(TCR-FC) type SVC is recognized as having the most flexible control and high speed response, which has been widely utilized in power systems, is considered and designed to improve the response of a synchronous generator, as well as controlling the system voltage. A Fuzzy-PI controller for SVC system was proposed in this paper. The PI gain parameters of the proposed Fuzzy-PI controller which is a special type of PI ones are self-tuned by fuzzy inference technique. It is natural that the fuzzy inference technique should be based on humans intuitions and empirical knowledge. Nonetheless, the conventional ones were not so. Therefore, In this paper, the fuzzy inference technique of PI gains using MMGM(Min Max Gravity Method) which is very similar to humans inference procedures, was presented and applied to the SVC system. The system dynamic responses are examined after applying all small disturbance condition.

• Journal of Electrical Engineering and Technology
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• v.10 no.1
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• pp.280-287
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• 2015

Three-level PWM rectifiers applied in medium voltage applications usually operate at low switching frequency to keep the dynamic losses under permitted level. However, low switching frequency brings a heavy cross-coupling between the current components $i_d$ and $i_q$ with a poor dynamic system performance and a harmonic distortion in the grid-connecting current. To overcome these problems, a mathematical model based on complex variables of the three-level voltage source PWM rectifier is firstly established, and the reasons of above issues resulted from low switching frequency have been analyzed using modern control theory. Then, a novel control strategy suitable for the current decoupling control based on the complex variables for $i_d$ and $i_q$ is designed here. The comparisons between this kind of control strategy and the normal PI method have been carried out. MATLAB and experimental results are given in detail.

• Proceedings of the KIEE Conference
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• 2004.10a
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• pp.176-178
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• 2004

Precise control of interior permanent magnet synchronous motor(IPMSM) over wide speed range is an engineering challenge. This paper considers the design and implementation of novel technique of speed estimation and control for IPMSM using hybrid intelligent control. The hybrid combination of neural network and adaptive fuzzy control will produce a powerful representation flexibility and numerical processing capability. Also, this paper is proposed speed control of IPMSM using adaptive neural network fuzzy(A-NNF) and estimation of speed using artificial neural network(ANN) controller. The back propagation neural network technique is used to provide a real time adaptive estimation of the motor speed.

• Proceedings of the KIEE Conference
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• 2008.10b
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• pp.464-465
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• 2008

This paper proposed a robust controller in order to handle the boom vibration of inspection robot. While a inspection robot moves on boom with vibration by weight occurs. Therefore, Boom as structure like cantilever beam appears vibration by weight of inspection robot. The Z axis of inspection robot operates with Sliding structure. inspection robot is used "Fuzzy Controller" for position control with Z axis. The developed robot system is composed of the specially designed car for inspection robot. The proposed Fuzzy Controllers are used to track position reference signal of Z axis. A Experiment verify that the proposed Fuzzy Controller design method can achieve favorable control performance with regard to external disturbance.