• International Journal of Aeronautical and Space Sciences
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• 제16권2호
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• pp.278-294
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• 2015

Considering the guidance and control problem of the near space interceptor (NSI) during the terminal course, this paper proposes a three-channel independent integrated guidance and control (IGC) scheme based on the backstepping sliding mode and finite time disturbance observer (FTDO). Initially, the three-channel independent IGC model is constructed based on the interceptor-target relative motion and nonlinear dynamic model of the interceptor, in which the channel coupling term and external disturbance are regarded as the total disturbances of the corresponding channel. Then, the FTDO is introduced to estimate the target acceleration and control system loop disturbances, and the feed-forward compensation term based on the estimated values is employed to effectively remove the effect of disturbances in finite time. Subsequently, the IGC algorithm based on the backstepping sliding mode is also given to obtain the virtual control moment. Furthermore, a robust least-squares weighted control allocation (RLSWCA) algorithm is employed to distribute the previous virtual control moment among the corresponding aerodynamic fins and reaction jets, which also takes into account the uncertainty in the control effectiveness matrix. Finally, simulation results show that the proposed IGC method can obtain the small miss distance and smooth interceptor trajectories.

• 대한기계학회논문집
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• 제16권7호
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• pp.1332-1340
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• 1992

본 연구에서는 제어기에 관심을 갖던 기존의 방법에서 탈피해서 포화요소에 촛점을 맞추어 와인드업 현상을 해결하는 방법을 제시하고자 한다. 이 방법은 단입 출력 시스템에서는 역계산방법(back calculation method)과 동일하나 제어기와 보상기 를 분리하여 설계한 후 보상기를 각각의 엑추에이터 앞에 설치함으로써 다입 출력 시 스템에 쉽게 적용될 수 있다는 점에서 새로운 제안이라 할 수 있다. 또한 제어기를 바꾸지 않고도 보상기만을 추가로 설치하여 와인드업을 방지할 수 있으므로 이미 설치 된 시스템에의 적용이 용이함도 특기할 만하다.

• 한국정밀공학회지
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• 제21권1호
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• pp.101-108
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• 2004

An electro-hydraulic manipulator using hydraulic actuators has many nonlinear elements, and its parameter fluctuations are greater than those of an electrically driven manipulator. So it is relatively difficult to obtain stable control performance. In this report, we applied disturbance estimation and compensation type robust control to all axes in a 3-link electro-hydraulic manipulator. From the results of experiment, it was confirmed that the performance of trajectory tracking and attitude regulating is greatly improved by the disturbance observer, which model is the same for each axis. On the other hand, for the autonomous assembly tasks, it is said that compliance control is one of the most available methods. Therefore we proposed compliance control which is based on the position control by disturbance observer for our manipulator system. To realize more stable contact work, the states in the compliance loop are feedback, where not only displacement but also velocity and acceleration are considered. And we applied this compliance control to Peg-in-Hole insertion task and analyzed mechanical relation between peg and hole. Also we proposed new method of shifting the position of end-effector periodically for the purpose of smooth insertion. As a result of using this method, it is experimentally confirmed that Peg-in-Hole insertion task with a clearance of 0.05［mm］can be achieved.

• 한국항행학회논문지
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• 제18권5호
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• pp.455-460
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• 2014

장거리 광전송 시스템에서 그룹 속도 분산과 비선형 현상에 의한 왜곡을 보상할 수 있는 분산 제어 (DM; dispersion management)와 광 위상 공액 기술이 결합된 전송 링크의 최적 설계를 위한 성능 분석을 수행하였다. 즉 전체 전송 링크의 중간에 위치한 광위상 공액기 (OPC; optical phase conjugator) 양쪽의 전송 구획에서의 잉여 분산의 상호 관계가 최적 전체 잉여 분산 (NRD; net residual dispersion)에 미치는 영향을 살펴보았다. 시뮬레이션 결과 전반 전송 구획에서의 잉여 분산과 후반 전송 구획에서의 잉여 분산의 차이를 10 ps/nm로 하여 전체 전송 링크의 NRD를 10 ps/nm로 설정하여야 가장 우수한 보상이 이루어진다는 것을 확인하였다.

• 한국항행학회논문지
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• 제17권1호
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• pp.16-23
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• 2013

단일 모드 광섬유의 그룹 속도 분산과 비선형 효과에 의해 왜곡되는 960 Gbps 파장 분할 다중 신호의 보상을 위해 분산 제어 기술이 적용된 광전송 링크에서 분산 보상 광섬유 (DCF; dispersion compensating fiber)의 분산 계수와 중계 구간 당 잉여 분산량 (RDPS; residual dispersion per span)이 왜곡 보상에 미치는 영향을 분석하였다. 우선 왜곡 보상에 큰 영향을 미치는 최적 전체 잉여 분산량 (NRD; net residual dispersion)은 고려한 모든 DCF의 분산 계수와 RDPS에 관계없이 큰 입사 전력에서 구해야 한다는 것을 확인하였다. 중계 구간의 RDPS는 매우 작게, 반면 DCF의 분산 계수는 크게 하여야 시스템 성능이 현저하게 개선되는 것을 확인하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.932_933
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• 2009

A technology based on thyristors will be used to manufacture the super-conducting coil AC/DC converters because of the low ratio of cost over installed power compared to a design based on GTO or similar technology. But phase-controlled converter suffers from fundamental disadvantage. They inject current harmonics into the input ac mains due to their nonlinear characteristics, thereby distort the supply voltage waveform, and demand reactive power from the associated ac power system at retarded angles. To overcome this disadvantage, in the case of two series converters at the DC side, connected to the same step-down transformer, apply for the sequence control. It is the most simple and efficient way to reduce the reactive power consumption at low cost. Analytical sequence control algorithm is suggested, the validity of the proposed scheme has been verified by experimental results with the small-scaled International Thermonuclear Experimental Reactor (ITER) Power Supply to minimize reactive power consumption.

• 전기학회논문지P
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• 제59권2호
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• pp.141-145
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• 2010

Most of the industrial loads includes the non-linear load as well as the linear load because there are many kinds of power conversion equipments at the input stage of the load in distribution network. The non-linear load causes the distortion of voltage waveform at PCC because the non-linear load generates the harmonic current. As a result, various voltage harmonics are existed at PCC depending on the current harmonics from the non-linear load. And, a series reactor is generally connected to the power capacitor in series to attenuate the distortion of voltage waveform and to reduce an inrush current of power capacitor. Also, harmonic current of power capacitor is highly dependent on the series reactor because it is operated with the power capacitor as a passive filter against nonlinear loads. Then, these capacitors might be damaged by the excessive voltage and current harmonic components. In this paper, we presented how to select the capacitor and series reactor to meet the requirement of the voltage distortion at PCC and analyzed the voltage, current and capacity rating of the power capacitor by the computer simulation to ensure the safe operation of power capacitor when the voltage harmonics at PCC are existed. Also, the analysis data were compared with the experimental measurements for the verification.

• 한국위성정보통신학회논문지
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• 제3권1호
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• pp.15-21
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• 2008

OFDM (직교 주파수 분할 다중화) 신호의 높은 PAPR은 시스템의 송신단에서 전력증폭기의 비선형적 특성으로 인해 비선형 왜곡이 불가피하게 발생한다. 이 현상은 대역 내 왜곡과 대역 외 방사를 초래한다. 본 논문에서는 다항식 (polynomial) 모델에 기반한 사전왜곡(pre-distortion) 기법으로 이러한 문제를 보상하는 기법을 제안한다. 비선형 및 역비선형 다항식 모델 추정은 LSE(Least Square Error) 알고리즘으로 수행한다. 또한 시스템의 성능 향상을 위해 피크제거와 클리핑 결합기법을 이용해 OFDM 신호가 전력증폭기의 포화 영역 근처에서 동작함으로써 발생하는 왜곡된 신호의 진폭을 제거한다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.265-270
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• 2005

This paper presents a new attitude stabilization and control of an unmanned helicopter based on neural network compensation. A systematic derivation on the dynamics of an unmanned small-scale helicopter is performed. Combined rotor-fuselage-tail dynamics is derived in body-fixed reference frame with its origin at the C.G. of the helicopter. And the resulting nonlinear equation of motion consists of 6-DOF air vehicle dynamics as well as the rotor flapping and engine torque equations. A simulation model was modified using the existing simulator for an unmanned helicopter dynamic model, which reflects the unmanned test helicopter(CNUHELI). The dynamic response of the refined model was compared with the flight test data. It can be shown that a good coincidence was accomplished between the real unmanned helicopter system and the mathematical model. This dynamic model was linearized for classical controller design using small perturbation method. A Neuro-PD control system was designed for both longitudinal and lateral flight modes, and the results were compared with the PD-only control response. Simulation results show that the proposed Neuro-PD control system demonstrates better performance.

• 한국지능시스템학회논문지
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• 제14권3호
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• pp.375-382
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• 2004

신경회로망을 이용한 XY 테이블의 비선형 보상기법을 제안한다. 제안된 신경망 제어기는 시스템의 비선형 성분에 의한 성능저하를 보상하는 신경회로망과 시스템의 안정화를 위한 비례미분(PD) 제어기로 구성된다. 신경망 보상 구조가 적응적이고 추적오차와 파라미터 추정치가 유계가 되는 신경망 파라미터 동조알고리듬과 안정도 증명을 제시한다. 신경망 제어기를 위치 테이블에 실험함으로써 비선형 성분에 의한 성능저하를 줄이는 효과를 보여준다.