• Journal of the Korean Institute of Telematics and Electronics B
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• v.30B no.9
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• pp.36-44
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• 1993

In the development of a high speed and light weight manipulator, it is necessary to consider the flexibility of a robotic arm. The infinite dynamics must be analyzed to obtain the finite mode modeling to achieve the feasible controller design of the robotic arm. The modeling procedures of the flexible robot arm, and natural frequencies and mode shapes by the constrained and unconstrained mode method are illustrated. The transfer function of the robot arm with a payload is also shown. The controller is designed by the pole assignment and optimal control theory to compensate for the unmodelled dynamic effects to the low order system. Also, the pole assignment method involving the harmonic vibration mode is presented through computer simulation.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.54 no.3
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• pp.119-128
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• 2005

In this paper, an robust adaptive backstepping controller is proposed for the chaos system with disturbances. This controller will be applicable to the chaos system of strict-feedback form and utilize the saturation function for decreasing the effect of disturbances derived from unmodelled dynamics and external noise. It shows that backstepping algorithm can be used to solve the problems of nonlinear system very well and robust controller can be designed without the variation of adaptive law. Simulation results are provided to demonstrate the effectiveness of the proposed controller.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10b
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• pp.378-384
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• 1993

In this paper, an intelligent adaptive controller is proposed for the process with unmodelled dynamics. The intelligent adaptive controller consists of the numeric adaptive controller and the intelligent tuning part. The continuous scheme is used for the numeric adaptive controller to avoid the problems occurred in the discrete time schemes. The adaptive controller is adopted to the process with time delay. It is an implicit adaptive algorithm based on GMV using the emulator. The tuning part changes the design parameters in the control algorithm. It is a multilayer neural network trained by robustness analysis data. The proposed method can improve the robustness of the adaptive control system because the design parameters are tuned according to the operating points of the process. Through the simulation, robustnesses are shown for intelligent adaptive controller. Finally, the proposed algorithms are implemented on the electric furnace temperature control system. The effectiveness of the proposed algorithm is shown from experiments.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.5
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• pp.65-72
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• 2000

This paper presents the study of the tension control in a web transfer system. In this study the sliding mode controller is applied to a time-varying nonlinear mathematical model. The model was derived to consider the effects of changing the roll radius in tension variation during winding and unwinding. The uncertainty in modeling may be due to unmodelled dynamics, on variations in system model. Designed sliding mode controller made the system error always staying in the suggested surface from the beginning. Through this, system is maintained to be robust against a disturbance and uncertainty. To verify the designed controller has a good performance, various inputs such as desired velocity, step input, and trapezoidal input are applied. When the sliding mode controller was used, the system(the tension control) performance was improved comparing to the PID controller. The robustness of the controller with respect to an estimation error was verified through simulations.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.2
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• pp.146-154
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• 2000

An $H\infty$ controller is designed for active suspensions of vehicles using 7-degree-of-freedom full-car model. Its performance robustness as well as stability robustness to system parameter variations and unmodelled dynamics are assured through the $\mu$-framework. The performance of the $H\infty$ controller is compared with that of a LQC controller in compute simulations. From the simulations it is found that the active suspension with the $H\infty$ controller reduces the acceleration and motion of the sprung mass in the heaving rolling and pitching directions when the car is driven on a normal road or through an asymmetric bump. The suspension stroke and the road holding capability are also improved with a relatively small level of power consumption. Overall the $H\infty$ controller shows a more robust performance than that of the LQG design.

• Journal of Electrical Engineering and Technology
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• v.12 no.4
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• pp.1537-1547
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• 2017

In this paper, a discrete-time robust current controller is proposed for PMSM drives. The structure of the proposed controller is quite simple and does not require high computational resource. The only difference of the proposed controller from the classical dead-beat controller is the integral term which can easily be implemented in a PMSM drive. The stability analysis of the proposed controller is performed accounting in parametric uncertainties, unmodelled dynamics and disturbances in the mathematical model. The boundedness of the dynamical system and asymptotic convergence of dq-axes currents to their reference values are provided under certain conditions. Various simulation and experimental studies are performed and the results taken at different operation conditions show the validity of the proposed controller.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.36 no.7
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• pp.484-491
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• 1987

A sufficent condition for the robust control of the adaptive control system is presented under the convergence of the parameters of the adaptive system. The plant in the adaptive control system is a stable system which includes the unmodelled dynamics and can be approximated by a minimum phase system. It is shown that modified structure which Kosut and Friedlander suggested satisfies the sufficient condition more easily than the original structure without modification. It is also shown by computer simulation that the modified structure and/ or the adaptation method using the normalized input and output data or filtered input and output data can improve the robustness of the adaptive control system.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.52 no.6
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• pp.323-332
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• 2003

This paper proposes a variable structure position controller for an induction motor(IM) which uses a reaching law and an integral compensating nonlinear switching function. With the integral compensating nonlinear switching function, both very low overshoot and high steady state control accuracy can be obtained by compensating the states chattering problem due to the unmodelled dynamics of inverter and feedback sensors. With the reaching law, reaching mode can be established quantitatively during transient state so that dynamic control performance is improved. For experiment a digital servo driver which consists of a DSP and an IPM inverter was developed. With the various experimental results, IM position control performance was verified.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.6
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• pp.1346-1360
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• 1989

본 연구에서는 기준 모델 적응제어 방식에서 직접 적응제어 방식을 사용하여 부하의 변동 및 외란이 발생할 경우에도 매니퓰레이터의 정확한 궤적의 추종 및 속도 의 실시간 제어가 가능한 적응제어시스템을 설계하고자 한다. 제2절에서는 로봇 매니퓰레이터의 기구학적 이론 및 동적 모델링에 대한 기본이론을 전개하고, 제3절 에서는 제어시스템의 설계를 위한 제어 알고리즘과 초안정(hyperstability)이론을 통한 안정성 해석을 다룬다. 그리고 제4절에서는 제안된 제어기의 성능 평가를 위해 6관절 로봇인 스탠포드 로봇 매니퓰레이터에 대한 시뮬레이션을 통한 결과를 토오크 계산법(computed torque method)에 의한 결과와 비교 검토함으로서 제안된 제어기의 성능을 예증한다.

• Proceedings of the KIEE Conference
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• 1998.07b
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• pp.414-416
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• 1998

One significant error in XY table is due to friction and disturbance. However, the characteristics of this friction is not easy to predict and analyze because of its nonlinearity. Therefore, it is difficult for conventional controller to compensate it effectively. In order to solve this problem, this paper presents a position controller based on fuzzy logic controller(FLC) that is suitable for system with unknown and unmodelled dynamics. The performance of the proposed controller are demonstrated by simulation results.