• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 추계학술대회논문집
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• pp.443-448
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• 2000

In this paper, we propose a novel adaptive feedforward controller for periodic disturbance and noise cancellation, with a frequency tracking capability. It can be added to an existing feedback control system without altering the original closed-loop characteristics, which is based on adaptive algorithm. We introduce novel algorithm "Constrained AFC(adaptive feedforward controller) algorithm" that increase the convergence region regardless of the delay in the closed loop system. In the algorithms, coefficients of the controller are adapted using the residuals of constrained structure which are defined in such a way that the coefficients become time invariant. The proposed algorithm not only estimate the magnitude and phase of the tonal disturbance and noise but also track the frequency of the tone, which changes in quasi-static manner. The frequency tracking algorithm uses the instantaneous frequency approach based on Hilbert transform. A number of computer simulations have been carried out in order to demonstrate the effectiveness of proposed method under various conditions.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.40-46
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• 1993

In this paper, we design a multirate controller for a given multirate sampled-data system which has a periodic output measurement scheme. A sufficient condition for maintaining observability in multirate sampled-data systems is given first. The design strategy for disturbance rejection is proposed. The proposed controller has IMC structure, and can be deomposed into a disturbance estimator and the inverse of fast plants.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 22-24 Oct. 1991
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• pp.243-247
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• 1991

A roll eccentricity controller for a tandem cold rolling process is designed to attenuate the outlet thickness deviation due to roll eccentricity. In order to design the controller, the excess stability margin is maximized by solving a standard H.inf. optimization problem under the requirement that ensure disturbance rejection for a class of disturbance. Robust performance of the proposed controller is checked by a computer simulation.

• 제어로봇시스템학회논문지
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• 제8권7호
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• pp.547-555
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• 2002

This paper proposes a stabilizing controller for the multirate sampled-data systems, which have a periodic output measurement scheme, in case of the open-loop unstable plant. A sufficient condition for maintaining observability in the multirate sampled-data systems is derived and a design strategy for filtered disturbance rejection is proposed. We also propose a design method for the plant output estimator. It is shown that the proposed pre-stabilizing controllers can stabilize the plant through the simulations. The proposed controller has IMC structure, and can be decomposed into the pre-stabilizing controller, the plant output estimator, the filtered disturbance estimator and the inverse of the fast pre-stabilized plant model. We assume that the plant is open-loop unstable and the disturbance consists of a sum of finite number of sinusoids with different frequencies. Some examples are presented for illustrations.

• 전자공학회논문지SC
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• 제48권4호
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• pp.17-24
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• 2011

본 논문에서는 알 수 없는 주파수를 가지는 주기적인 외란이 존재하는 광디스크 드라이브에 대하여 주파수 적응 알고리즘과 출력 제어기를 추가하여 외란을 제거하는 제어기법을 제안한다. 여기서 IMP(internal model principal)에 기반을 두는 주파수 적응 알고리즘은 주기적인 외란의 주파수를 알아내는 역할을 한다. 전체 시스템의 안정도 및 외란제거 성능은 특이섭동이론(singular perturbation theory)으로 증명된다. 본 논문의 기여는 주파수 범위에 따른 설계의 제약이 없다는 점과 모델 불확실성이 존재할 때도 외란을 제거할 수 있다는 점을 들 수 있다.

• 수산해양기술연구
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• 제59권2호
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• pp.145-154
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• 2023

In this study, to control the heading angle of a ship, which is constantly subjected to various internal and external disturbances during the voyage, an LADRC (linear active disturbance rejection control) design that focuses more on improving the disturbance removal performance was proposed. The speed rate of change of the ship's heading angle due to the turn of the rudder angle was selected as a significant factor, and the nonlinear model of the ship's maneuvering equation, including the steering gear, was treated as a total disturbance. It is the similar process with an LADRC design for the first-order transfer function model. At this time, the gains of the controller included in LADRC and the gains of the extended state observer were tuned to RCGAs (real-coded genetic algorithms) to minimize the integral time-weighted absolute error as an evaluation function. The simulation was performed by applying the proposed GA-LADRC controller to the heading angle control of the Mariner class vessel. In particular, it was confirmed that the proposed controller satisfactorily maintains and follows the set course even when the disturbances such as nonlinearity, modelling error, uncertainty and noise of the measurement sensor are considered.

• 전기전자학회논문지
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• 제24권1호
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• pp.154-160
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• 2020

본 논문에서는 계통연계인버터용 정지좌표기반 전류제어알고리즘을 제안한다. PI 제어기는 계통 연결 인버터의 전류 제어기로 사용되고 있다. 정지좌표기반 PI 제어기를 사용할 경우, AC 신호 제어로 인하여 정상 상태 오류와 위상지연현상이 발생한다. 본 논문에서는 전향보상기를 추가하여 명령 추적 성능을 높이고 과도 응답을 개선하는 방법을 제안한다. 또한 계통 전압을 외란으로 사용하여 계통 오류 발생 시 시스템을 보호하기 위해 외란을 측정 및 제거하는 제어 방법을 제안한다. 제안된 제어 방법은 수학적으로 유도하고 전달 함수로 표현하였으며 시뮬레이션을 통하여 검증하였다.

• 대한기계학회논문집A
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• 제29권4호
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• pp.591-599
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• 2005

This paper proposes a systematic design methodology for high-speed/high-precision servomechanisms by using a disturbance observer. A multiplicative uncertainty model and a two degree-of-freedom controller composed of a disturbance observer (DOB) and a PD controller are considered as subsystems. Analysis of the system performance, such as internal stability and bandwidth of a servomechanism according to subsystem parameters is conducted for better understanding of the dynamic behavior and interactions among the subsystem parameters. Then, an integrated design methodology, where the interactions are considered simultaneously, is applied to design processes of the servomechanism. The tradeoff relationship between disturbance suppression and measurement noise rejection of the DOB is considered through the design process. Numerical case studies show the improved possibility to evaluate and optimize the dynamic motion performance of the servomechanism. Moreover, the disturbance observer designed based on the proposed design methodology yields excellent disturbance suppression performance.

• 소음진동
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• 제11권1호
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• pp.49-56
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• 2001

In this paper, two plant models, of which one is newly developed and the other one is the conventional one, of the focus servo system of DVD drive are presented and a two-degree-of freedom controller consisted of Inverse dynamics feedforward and LQG/LTR feedback controller is designed. The newly developed plant model is used to design the feedforward controller and the conventional model is used for the design of feedback controller. The output of newly developed model is the displacement of objective lens and the output of conventional model is the focus error of the DVD focus servo system. The displacement of the objective lens is estimated by the dynamics model of the DVD focus servo system. The disturbance rejection performance of the two-degree-of freedom controller is compared with that of an LQG/LTR one.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 B
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• pp.515-517
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• 1999

This paper considers the design of the effective controllers for the plant with an integrator and a long deadtime. The structure of the new DTC(DeadTime Compensator) that has an additive filter is proposed. Our DTC shows the improved performance in set-point response and disturbance rejection. Especially the bad effect of the long deadtime in the disturbance rejection is fairly reduced by using the additive filter. Illustrative examples are provided to show the availability of the proposed controller.