• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.330-335
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• 1998

In this paper the robust vector control method of induction motor for the purpose of improving the system performance deterioration caused by parameter variations is proposed. The estimations of the stator current and the rotor flux are obtained by the full order state observer with corrective prediction error feedback. and the adaptive scheme is constructed to estimate the rotor speed with the error signal between real and estimation value of the stator current. Adaptive sliding observer based on the variable structure control is applied to parameter identification. Consequently predictive current control and speed sensorless vector control can be obtained simultaneously regardless of the parameter variations.

• Journal of Power Electronics
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• v.12 no.6
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• pp.904-911
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• 2012

This paper presents a fuzzy adaptive speed controller that guarantees a fast dynamic behavior and a precise trajectory tracking capability for surfaced-mounted permanent magnet synchronous motors (SPMSMs). The proposed fuzzy adaptive control strategy is simple and easy to implement. In addition, the proposed speed controller is very robust to system parameter and load torque variations because it does not require any accurate parameter values. The global stability of the proposed control system is analytically verified. To evaluate the proposed fuzzy adaptive speed controller, both simulation and experimental results are shown under motor parameter and load torque variations on a prototype SPMSM drive system.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.4
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• pp.590-595
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• 1996

The robust control technique is generally the iterative design method to determine a robust control for perturbed system with prescribed range of perturbation based on the robust stability measure. However, robot manipulator has the structured pertubation and the unstructured one. This paper proposes the robust technique for designing controller such that the trajectory of end-effector of robot manipulator tracks asymptotically the desired trajectory for all allowable variations in the manipulator's parameter. For satisfying asymptotical stability though we can not know the bound of perturbations and the parameter variations, the relation between the unknown parameter and the parameter of nominal system can be derived from Krasovskii theorem and we construct the new robust control using that relation. (author). 12 refs., 6 figs.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.1
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• pp.136-144
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• 2004

In general a hydraulic system which uses a single rod hydraulic as an actuator is modeled as a nonlinear system and reveals uncertain Parameter characteristics such as the density variation of hydraulic oil and is subject to load variations and severe disturbances during operation. A variable design-parameter fuzzy PID controller is adopted to solve these undesirable internal and external problems and its effectiveness is verified through computer simulations for control performance and real time control possibility.

• Journal of Korea Society of Industrial Information Systems
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• v.7 no.4
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• pp.66-73
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• 2002

Although the general sliding mode control has the robust property, bounds on the disturbances and parameter variations are known to the designer of the system control. But sometimes these bounds may not be easily obtained. However, fuzzy control provides an effective way to design the controller of the system with the disturbances and parameter variations. Therefore, combination of the best feature of fuzzy control and sliding mode control is considered. When using the conventional VSC, generally the reaching phase problem occurs, which cause the system response to be sensitive to parameter variations and external disturbances. In order to overcome these problems, an adaptive fuzzy VSC with sliding surface eliminating reaching phase is proposed. The validity of the proposed scheme is shown by results of experiments for the BLDC motor.

• Journal of Institute of Control, Robotics and Systems
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• v.3 no.1
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• pp.9-16
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• 1997

The method of designing robust two degree of freedom(2 DOF) controllers for linear systems with parameter uncertainties and unmodeled dynamics is presented in this paper. Robust performance condition that accounts for robust model matching of closed loop system and disturbance rejection is derived. Using the robust performance condition, the feedback controller is designed to meet robust stability and disturbance rejection specifications, while prefilter is used to improve the robust model matching properties. The $H^{\infty}$ and $\mu$ controller for six degree of freedom vehicle with parameter variations are designed and compared. Simulations for hydrodynamic parameter variations and disturbance are presented to demonstrate the achievement of good robust performance.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.451-456
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• 1991

A robust position control scheme for DC Motor is proposed based on Fuzzy Acceleration Control. Proposed control system has the similar structure that Y. Hori proposed. But the PI type acceleration controller of it is replaced by Fuzzy Logic Controller(FLC) which is known to be robust to the operating point and parameter variations. By the simulation study for a real DC Motor, we have slowed the superiority to the continuous PI acceleration controller in the view point of robustness to the operating point and parameter variations.

• Journal of the Korean Society for Precision Engineering
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• v.6 no.2
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• pp.65-76
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• 1989

The objective of this paper is to design the variable structure system(VSS) controller for the tracking control of excavator which is driven by electro-hydraulic servomechansim. It is generally agreed that the dynamic characteristics of the robot arm such as excavator are coupled, time varying, and highly nonlinear, and also hydraulic system contains nonlinear characteristics in itself, so performing exact position control and trajectory tracking control need remarkable consideration. To solve this porblem, this system was designed as a variable structure system. The salient feature of VSS is that the sliding mode occur on a switching surface. While in sliding mode, the system remains insensitive to parameter variations and disturbances. This control algorithm was applied to a hydraulic excavator by simulaltion and to a simulator by experiment. And its effectiveness was verified. And the results of VSS for the electro-hydraulic excavator was compared with that of the PID when load disturbances and system parameter variations exist.

• International Journal of Control, Automation, and Systems
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• v.5 no.6
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• pp.607-613
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• 2007

Eigenstructure assignment provides the advantage of allowing great flexibility in shaping the closed-loop system responses by allowing specification of closed-loop eigenvalues and corresponding eigenvectors. But, the general eigenstructure assignment methodologies cannot guarantee stability robustness to parameter variations of a system. In this paper, we present a novel method that has the capability of exact assignment of an eigenstructure which can consider the probability of instability for LTI (Linear Time-Invariant) systems. The probability of instability of an LTI system is determined by the probability distributions of the closed-loop eigenvalues. The stability region for the system is made probabilistically based upon the Monte Carlo evaluations. The proposed control design method is applied to design a flight control system with probabilistic parameter variations to confirm the usefulness of the method.

• 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.