• The Korean Journal of Ecology
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• 제21권3호
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• pp.233-241
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• 1998

In order to test of intermediate disturbance hypothesis that an intermediate level of disturbance maximize biodiversity and to elucidate the effect of disturbance during the early old-field succession, the response of plant community along an experimental disturbance gradient was investigated in a five-year old-field. Response of plant community along an experimental disturbance gradient was connected with light condition because artificial disturbance gradient had been treat by clipping of plants and removing of litter. Artificial disturbance in five-year old-field plant community retarded rate of succession by increasing invasion and performance of the earlier successional species in the initial and middle stage of disturbance treatment. The species richness in the blocks of intermediate disturbance level showed the peak in early and mid-summer. This result did correspond with the prediction of intermediate disturbance hypothesis.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.24-27
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• 1997

A periodic disturbance canceler is proposed to compensate the periodic disturbance due to cutting process in a CNC machining center. For precision cutting, the combination of a disturbance observer and a periodic disturbance canceler is desirable in order to compensate both the frictional force and the periodic disturbance. This method is implemented in a position control system of a CNC machining center in cutting process and the experimental results are described to show its effectiveness.

• 전기학회논문지
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• 제59권12호
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• pp.2278-2283
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• 2010

This paper deals with the pendubot control using disturbance observer. Experimental results for the motion of pendubot with balancing control show that the limit cycle can be attributed to the disturbance. Therefore, we propose the disturbance compensation method using by disturbance observer to compensate for the disturbance. Through the experimental results, the effectiveness of the proposed method is verified.

• 대한전기학회논문지:시스템및제어부문D
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• 제53권6호
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• pp.408-414
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• 2004

In this paper, a disturbance observer based sliding mode control is proposed to attenuate disturbance responses in an active magnetic bearing system, which is subject to base motion. An algorithm which decouples disturbance observation dynamics from sliding mode dynamics is suggested. This algorithm preserves the robustness of the sliding mode control and satisfies reachability condition in the presence of external disturbance and parameter uncertainties. Along with experimental results, it is shown that the proposed control is effective in disturbance rejection without any additive disturbance measurement.

• 로봇학회논문지
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• 제18권1호
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• pp.82-87
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• 2023

This paper proposes a disturbance observer-based control for 6-DOF remotely operated underwater vehicles with model uncertainties. The sum of external disturbance and the forces generated from model parameters except for the inertial matrix of the hydrodynamic model is defined as a lumped disturbance in this paper. Then, the lumped disturbance caused by model uncertainties and the external forces is estimated using the disturbance observer. Fortunately, the disturbance observer is constructed as a linear form because all the elements of the inertial matrix of the hydrodynamic model are constants. To verify the proposed control scheme, we show that the actual lumped disturbance is similar to the estimated lumped disturbance obtained by the disturbance observer. Finally, the position tracking performance in the disturbance environment is confirmed through the comparative study with a traditional inverse dynamics PD controller.

• 한국항공운항학회지
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• 제26권2호
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• pp.61-67
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• 2018

This paper presents a method to apply disturbance observer to PID controller for robustness enhancement of UAVs. The system uncertainties and disturbances bring adverse effects on performance and stability of UAVs. In this paper, we estimate the acceleration disturbances using nonlinear disturbance observer, then compensate disturbances with composite controller. By employing nonlinear disturbance observer and composite controller, we have better performance and robustness than conventional PID controller. The asymptotical stability of nonlinear disturbance observer is presented through theoretical analysis. The estimation performance of nonlinear disturbance observer is evaluated by numerical simulation. And performance of disturbance observer based PID controller is evaluated by comparing the performance with conventional PID controller.

• 전기학회논문지
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• 제56권10호
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• pp.1844-1851
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• 2007

This paper presents methods for the compensation of sinusoidal disturbances with unknown amplitude, phase, and time-varying frequency in nonlinear systems. In the previous disturbance accommodation methods, the sinusoidal disturbance with unknown time-invariant frequency was considered. In the proposed method, the disturbance with unknown time-varying frequency is compensated. As for the control structure, two control inputs are designed separately in such a way that one of them is designed for the nonlinear system control without considering the disturbance, and the other one uses the disturbance estimate obtained from the disturbance accommodating observer. The stability analysis is done considering the disturbance estimation error and the numerical simulation demonstrates the proposed approach.

• 전기학회논문지
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• 제65권4호
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• pp.652-658
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• 2016

In practical control systems differences between nominal and real systems arise from internal uncertainties and/or external disturbances. This paper presents a model-based low-order disturbance observer for a sinusoidal disturbance with unknown constant offset. By using the disturbance model of a biased harmonic signal, the proposed method can successfully estimate the biased sinusoidal disturbance with unknown amplitude and phase but known frequency. At the first stage of the observer design, a model-based disturbance observer is designed when all the system states are measurable. Next, a sufficient condition is presented for the proposed observer to estimate the sinusoidal disturbance with a minimal-order additional dynamics using only output measurement. Comparative computer simulations are performed to test the performance of the proposed method. The simulation results show the enhanced performance of the proposed disturbance observer.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.22-25
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• 2005

In the paper, algorithms for disturbance observers are newly presented in the time-domain. Attention is paid to observing a ramp disturbance by introducing an integral term to the output equation of a constant disturbance observer. In order to reduce the sensitivity to the measurement noise, the disturbance observer is combined with the state observer. It will be shown that the estimation dynamics can be arbitrarily chosen by assigning the eigenvalues of a characteristic equation. Also, we provide the analysis of observer behaviors subject to non-ramp-style disturbances. Finally, we propose the generalized disturbance observer that accurately estimates disturbances of higher order in time series expansion.

• 전자공학회논문지SC
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• 제47권2호
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• pp.16-24
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• 2010

본 논문은 불특정한 외란을 가진 비선형 시스템에서의 백스태핑 기법을 이용한 새로운 퍼지 외란 관측가 설계 방법을 제안한다. 먼저, 퍼지 논리 시스템을 이용하여 불특정한 외란을 관측하기 위한 관측 입력을 가진 퍼지 외란 관측기를 설계한다. 제안된 외란 관측기가 불특정한 외란을 관측하는 것을 증명하기 위해 와란 관측 오차 시스템을 도입한다. 백스태핑 기법을 도입하여 각 단계에서의 퍼지 외란 관측기의 파라마터 적응 규칙과 외란 관측기의 관측 입력을 유도하고 외란 오차 시스템의 안정성을 증명한다. 제안된 외란 관측기의 명확성을 증명하기 위해서 모의 실험 예제들을 제공한다.