• Journal of Institute of Control, Robotics and Systems
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• v.2 no.4
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• pp.351-361
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• 1996

A variable structure controller is developed for an AC servo motor used in CNC milling machines. The designed controller is implemented as an outer loop controller to a factory designed motor-servopack system. The robustness parameter is tuned for a fast response when the speed tracking error is large, while it is tuned for small oscillations when the speed tracking error is small. The designed controller is installed on a CNC machine using a PC. Cutting experiments show improved performance over the factory-designed controller.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.472-474
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• 1994

A new integral variable structure system without the reaching phase problems is presented for the prescribed control of the BLDDSM under load variation and parameter uncertainties. The control technique can yields the complete robustness of initially prescribed output dynamics in the sliding surface against the modeling errors. The comparative simulation and experiment studies of the BLDDSM position control are carried out in comparison with two previous algorithms.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.277-279
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• 1994

In this paper, a novel field weakening scheme for the induction machine by the voltage control strategy is presented. The proposed algorithm ensures producing the maximum torque over the entire field weakening legion. Also by introducing the direct field-oriented control in the field weakening legion with large variation in machine parameters, the drive system can obtain the robustness to machine parameter variation. Moreover, by using estimated speed, sensorless speed control can be possible in very high speed lesion. Experimental results for a laboratory induction motor drive system confirm the validity or the proposed control algorithm.

• Journal of Information Processing Systems
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• v.13 no.2
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• pp.321-339
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• 2017

In this work, we are interested in the extraction of areas of interest from satellite images by introducing a MO-TRIBES/OC-SVM approach. The One-Class Support Vector Machine (OC-SVM) is based on the estimation of a support that includes training data. It identifies areas of interest without including other classes from the scene. We propose generating optimal training data using the Multi-Objective TRIBES (MO-TRIBES) to improve the performances of the OC-SVM. The MO-TRIBES is a parameter-free optimization technique that manages the search space in tribes composed of agents. It makes different behavioral and structural adaptations to minimize the false positive and false negative rates of the OC-SVM. We have applied our proposed approach for the extraction of earthquakes and urban areas. The experimental results and comparisons with different state-of-the-art classifiers confirm the efficiency and the robustness of the proposed approach.

• Proceedings of the KIEE Conference
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• 2004.10a
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• pp.179-181
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• 2004

This paper is proposed an adaptive fuzzy-neural network(A-FNN) controller based on the vector controlled induction motor drive system. The hybrid combination of fuzzy control and neural network will produce a powerful representation flexibility and numerical processing capability. Also, this paper is proposed speed estimation of induction motor using A closed-loop state observer. The rotor position is calculated through the stator flux position and an estimated flux value of rotation reference frame. A closed-loop state observer is implemented to compute the speed feedback signal. The results of analysis prove that the proposed control system has strong robustness to rotor parameter variation, and has good steady-state accuracy and transitory response.

• Journal of Power Electronics
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• v.16 no.4
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• pp.1387-1395
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• 2016

A method for the identification of mechanical parameters based on integral calculation is presented. Both the moment of inertia and the friction constant are identified by the method developed here, which is based on well-known mechanical differential equations. The mechanical system under test is excited according to a pre-determined low-frequency sinusoidal motion, minimizing the distortion, and increasing the accuracy of the results. The parameters are identified using integral calculation, increasing the robustness of the results against measurement noise. Experimental data are supported by simulation, confirming the effectiveness of the proposed technique. The performance improvements shown here are of use in the design of speed and position controllers and observers. Owing to its simplicity, this method can be readily applied to commercial inverter products.

• Journal of Advanced Marine Engineering and Technology
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• v.27 no.6
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• pp.759-766
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• 2003

The amount of container freight continuously has been increased. and the low efficiency of container crane causes jamming frequently in transportation and cargo handling at port. The conventional control techniques based on a mathematical model are not well suited for dealing with ill-defined and uncertain systems. Recently. Fuzzy control has been successfully applied to a wide variety of practical problems as robots. automatic train operation system. etc. In this paper. a fuzzy controller for container crane is proposed to accomplish a design of improved control system for minimizing the swing motion at destination. In this scheme a mathematical model for the system is obtained in state space form. Finally. to exhibit the tracking performance and robustness of the proposed controller. computer simulations were carried out with various references, parameter variations and disturbances.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.927-932
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• 2007

This paper proposes a robust back-stepping control with polynomial-type PD input for flexible joint robot manipulators to overcome parameter uncertainty. In the first step, a fictitious control is designed with polynomial-type PD input for the rigid link dynamic by the H-infinity control method. In second and third steps, the other fictitious control and real control are designed using saturation control and polynomial-type PD input based on the Lyapunov's second method. In each step, the designed robust inputs satisfy the L2-gain, which is equal to or less than gamma in the closed loop system. In contrast with the previous researches, the proposed method proves performance relations with PD gain from the robust gain. The performance robustness of the proposed control is verified through a 2-DOF robot manipulator with joint flexibility.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.9
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• pp.1741-1747
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• 2011

Though various techniques have been studied as a way of adjusting parameters of PID controllers, no perfect method of determining parameters is available to date. This paper proposes a new method for enhancing performance of PID controllers by using the characteristics of dual-input describing function (DIDF). In other words, if nonlinear elements with two inputs (DIDF) are connected in series to the plant, the critical point (-1+j0) for Nyquist stability theory can be moved to a position arbitrarily selected on the complex plane by determining necessary coefficients of the DIDF appropriately. This makes the application of the existing conventional PID parameter tuning methods a lot easier, and stability and robustness of the system are improved simultaneously due to the DIDF inserted.

• Proceedings of the KIEE Conference
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• 2007.11c
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• pp.160-164
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• 2007

MRAS observer, which is based on adaptive control theory, estimates speed and position by using optimal observer gains on the basis of Lyapunov stability theory. However, in case of MRAS theory, position estimation error is in existence because of non-linearity for inductance variation and limit cycles for position estimation. The adaptive sliding observer based on the variable structure control theory estimates the speed and position for zero of estimation error by using the sliding surface equal to the error between speed and position estimation. The binary observer estimates the rotor speed and rotor flux with alleviation of the high-frequency chattering, and retains the benefits achieved in the conventional sliding observer, such as robustness to parameter and disturbance variations. The speed and position sensorless control of SRM under the load and inductance variation is verified by the experimental results.