• Journal of Power Electronics
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• 제16권3호
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• pp.1025-1035
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• 2016

Luenberger observer (LO)-based sensorless multi-loop control of a converter requires an iterative trial-and-error design process, considering that many parameters should be determined, and loop gains are indirectly related to the closed-loop characteristics. Robust H∞ control adopts a compact sensorless controller. The algebraic Riccati equation (ARE)-based and linear matrix inequality (LMI)-based H∞ approaches need an exhaustive procedure, particularly for a low-order controller. Therefore, in this study, a novel robust H∞ synthesis approach is proposed to design a low-order sensorless controller for boost converters, which need not solve any ARE or LMI, and to parameterize the controller by an adjustable parameter behaving like a "knob" on the closed-loop characteristics. Simulation results show the straightforward closed-loop characteristics evaluation and better dynamic performance by the proposed H∞ approach, compared with the LO-based sensorless multi-loop control. Practical experiments on a digital processor confirmed the simulation results.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(2)
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• pp.965-968
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• 2003

This paper describes the PWM-VSI controller of three-phase UPS system using stationary reference frame. This controller meets the specification the UPS inverter output voltage even under the unbalanced or nonlinear load. This controller is also constructed with duble control loop of the outer voltage control loop and the inner current control loop. For the fast response of the output voltage control, yhr inner current control loop of the capacitor current os used. To get the good property against overshoot, the If controller us used. The outer voltage controller is designed with P controller and the high gain transfer function is used for the zero steady state error. All control gains of both controller is designed base on the CDM method.

• Journal of Power Electronics
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• 제7권4호
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• pp.310-317
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• 2007

In this paper, an analysis and hysteretic controller design of a $3^{rd}$ order buck converter is presented. The proposed hysteretic controller consists of an inner current-loop, just like the conventional cascade control scheme, and an outer voltage-loop for load voltage regulation. Although it is possible to include an inner current loop from different branches of the converter, from the feasibility and operational point of view, the load side capacitor current would be the better choice. The addition of an inner current-loop improves the dynamic performance of the converter while preserving the robustness of the hysteretic control. The controller formulation and closed-loop converter performance analysis are validated through computer simulations. Few experimental results of the proposed converter are given and compared with the buck converter.

• 대한전기학회논문지
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• 제38권2호
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• pp.119-126
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• 1989

In this paper, a new technique, which uses an "input compensator", is proposed to design a controller for the rebalance loop of a Dynamically Tuned Gyroscope (DTG) and the performance of this new controller is compared with that of a Proportional and Integral (PI) controller through simulation. The rebalance loop is an essential part of a DTG` it is composed of a controller, low-pass filters, notch filters and torque drivers. Among them, the controller is the main attributor to determine the performance of the rebalance loop. Through simulation, it is concluded that the performance of the newly designed controller is better than that of a PI controller in the point of (1) low maximum overshoot, (2) short settling time and (3) small steady state error.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제3권1호
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• pp.58-65
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• 2003

In this paper, a new model, which is a Takagi-Sugeno fuzzy model, for mobile robot is presented. A controller, consisting of two loops the one of which is the inner state feedback loop designed for stability and the outer loop is a PI controller designed for tracking the reference input, is suggested. Because the robot dynamics is nonlinear, it requires the controller to be insensitive to the nonlinear term. To achieve this objective, the model is developed by well known T-S fuzzy model. The design algorithm of inner state-feedback loop is regional pole-placement. In this paper, regions, for which poles of the inner state feedback loop are lie in, are formulated by LMI's. By solving these LMI's, we can obtain the state feedback gains for T-S fuzzy system. And this paper shows that the PI controller is equivalent to the state feedback and the cost function for reference tracking is equivalent to the LQ(linear quadratic) cost. By using these properties, it is also shown in this paper that the PI controller can be obtained by solving the LQ problem.

• 한국공작기계학회논문집
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• 제10권3호
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• pp.26-30
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• 2001

Controller refinement scheme to improve the performance of a conventional system automatically in frequency domain is proposed. The controller automatic tuning method features using experimental frequency responses of the conventional closed-loop system, the conventional controller, and the improved closed-loop system, instead of poorly modeled plant due to non-linearities and disturbances. The improved closed-loop system characteristics is automatically acquired by the con-ventional closed-loop system characteristics and the proposed performance index in system bandwidth. And the proper controller is realized by least squares approximation in frequency domain. To testify the usefulness of the approach, the path tracking control of robot arm is performed. Experimental results and analytic results are well-matched.

• Journal of international Conference on Electrical Machines and Systems
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• 제3권2호
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• pp.184-189
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• 2014

In this paper, a new design method of vibration suppression controller for multi-inertia (especially, 3-ineritia) resonance systems is proposed. The controller consists of a digital fuzzy controller for speed loop and a digital PI controller for current minor loop. The three scaling factor of the fuzzy controller and two PI controller gains are determined by Differential Evolution (DE). The DE is one of optimization techniques and a kind of evolutionary computation technique. In this paper, we have applied the DE/rand/1/bin strategy to design the optimal controller parameters. Comparing with the conventional design algorithm, the proposed method is able to shorten the time of the controller design to a large extent and to obtain accurate results. Finally, we confirmed the effectiveness of the proposal method by the computer simulations.

• 로봇학회논문지
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• 제13권3호
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• pp.157-163
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• 2018

This paper deals with the development and application of control algorithms for series elastic relief robots for rescue operations in harsh environment like disasters or battlefield. The joint controller applied in this paper has a cascade structure combining inner loop for torque control and outer loop for position control. The torque loop contains feedforward and feedback controller and disturbance observer for independent, decentralized joint control. The effect of the elastic component and motor dynamics are treated as the nonlinear disturbance and compensated with the disturbance observer of torque controller. For the collision detection, Band Designed Disturbance Observer is configured to recognize/respond to external disturbance robustly in the continuously changing environment. The controller is applied to a 7-dof series elastic manipulator to evaluate the torque tracking and collision detection/response performance.

• International Journal of Control, Automation, and Systems
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• 제5권3호
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• pp.243-250
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• 2007

This paper presents a systematic method of estimating a velocity disturbance occurring in the fine seek control system of an optical disk drive. A fine seek loop gain adjustment algorithm is introduced to accurately estimate the velocity disturbance in spite of the uncertainties of the fine actuator. The velocity disturbance can be estimated from a measurable velocity, a fine seek controller output, and a compensated fine actuator model. A robust fine seek controller can be designed by considering a minimum fine seek open-loop gain, calculated by the estimated velocity disturbance. The proposed controller design method is applied to the fine seek control system of a DVD rewritable drive and is evaluated through the experimental results.

• 한국산학기술학회논문지
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• 제15권11호
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• pp.6446-6451
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• 2014

공압모터는 저렴한 가격, 가벼운 무게, 용이한 조립, 중량대비 힘, 위험한 지역에서도 안전한 내부 구조와 더블어 매우 가혹한 환경에서도 작동하기 때문에 여러 분야의 응용에 매우 매력적이다. 이러한 장점에도 불구하고, 공압모터는 빠르고 정확한 응답을 필요로 하는 용도에 있어서 그 사용을 제한하는 여러 가지 바람직하지 않은 특성을 나타낸다. 이러한 바람직하지 않은 특성은 공기의 높은 압축성과 공압모터 구동시스템에 존재하는 비선형성에 기인한다. 본 논문에서는 공압모터의 회전각 제어시 강성을 높이기 위해 3-루프 기반 슬라이딩 모드 제어기를 제안하였으며 계단 응답과 외란 부하에 대한 응답 특성을 기존 PID 제어기와 비교 하였다. 공압모터 위치제어에 적용하여 본 결과 공압모터의 위치제어 정밀도는 ${\pm}0.05mm$ 이내로 제어할 수 있으며 부하에 대한 강성은 기존 PID제어기 보다 3.5배 향상됨을 보였다.