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조겸래,김해동,박수홍 釜山大學校生産技術硏究所 1998 生産技術硏究所論文集 Vol.55 No.-
한 곳의 관측소에서 얻은 모의 관측데이터를 이용한 위성의 궤도결정문제에 적용된 몇가지 비선형 필터들의 성능에 관한 비교연구를 하였다. 본 연구에서 적용된 비선형 필터들은 확장칼만필터(EKF), 반복 확장칼만필터(IEKF), 수정 가우시안 2차필터(MGSO), 칼만게인보상필터(KGC)와 수정 가우시안 2차필터 정도의 성능을 가지면서도 계산부담을 줄이기 위해 본 논문에서 제안하는 반복 칼만게인보상필터(IKGC)이다. 다양한 시물레이션 결과 IEKF, IKGC와 같이 반복과정을 채택한 필터들이 다른 필터들보다 성능이 우수했다. 비선형성이 크지 않은 경우에는 EKF와 MGSO, KGC는 같은 정도의 정확도를 가진다. IKGC는 비선형성을 가지는 비원형 저궤도위성의 궤도결정문제인 경우에 MGSO보다 계산 시간이 현저히 줄어들면서도 정확도면에서는 MGSO, KGC보다 향상이 있었다. This research compares the performance of several nonlinear filters which have been applied to the problem of orbit determination using simulated tracking data obtained from only one ground observation. The nonlinear filters investigated in this research are the extended Kalman filter(EKF), the iterated extended Kalman filter(IEKF), the modified Gaussian second order filter(MGSO), the Kalman gain compensated filter(KGC), and the iterated Kalman gain compensated filter(IKGC) which is proposed in this paper in order to avoid the computational burden and to improve the accuracy of the MGSO. The result of an extensive simulation shows that the filters using iteration like the IEKF and the IKGC are generally superior to all of the other filters. In a case where nonlinearities are not significant, the other filters such as the EKF, MGSO and the KGC can be utilized as they have approximately the same level of accuracy. The IKGC filter is shown to provide some improvement in orbit determination accuracy compared with the MGSO and the KGC. It also reduces substantially the computational time compared with the MGSO for noncircular low earth orbit satellites subject ot significant nonlinearities.
지구 비대칭 중력장과 대기모델에 따른 위성체의 수명 예측
조겸래,이일준,이대우 釜山大學校生産技術硏究所 1999 生産技術硏究所論文集 Vol.56 No.-
위성의 수명 및 소멸율은 섭동의 영향을 받고있는 위성의 궤도요소의 변화를 통해 결정되어질 수 있다. 섭동의 원인으로는 지구 비대칭 중력장, 대기저항, 태양과 달의 영향, 태양풍의 영향을 고려하였으며, 수치적분은 특수섭동법의 코웰의 방법을 이용하였다. 저궤도에서 운행되는 다복적 실용위성에 많은 영향을 줄수 있는 지구 비대칭 중력장과 대기저항에 대해 여러 가지 모델을 이용해서 위성에 미치는 영향을 연구하였다. 마지막에는 대기저항의 영향에 의한 수치적인 계산을 통해 위성이 가지는 수명과 소멸율에 대해서도 연구하였다. Life time and decay rate of a satellite can be determined through the variation of trajectory elements which are effected by perturbing disturbances. For the cause of the perturbind disturbances, non-symmetric gravity, force between sun and earth, atmospheric drag, and solar flux could be considered. Cowell's method is used for numerical integration. Various models, U.S.76, MSIS, and CIRA are utilized to investigate the effects due to non-symmetric gravity, atmospheric drag, and solar flux. Finally, life time and decay rate are studied through numerical computations due to the atmospheric drag.
유전 이론을 이용한 위성 임무 스케줄링 알고리즘의 제어상수에 따른 적합도 변화 연구
조겸래(Kyeum-Rae Cho),백승우(Seung-Woo Baek),이대우(Dae-Woo Lee) 제어로봇시스템학회 2010 제어·로봇·시스템학회 논문지 Vol.16 No.6
In this paper, the final fitness results of the satellite mission scheduling algorithm, which is designed by using the genetic algorithm, are simulated and compared with respect to the control constants. Heuristic algorithms, including the genetic algorithm, are good to find global optima, however, we have to find the optimal control constants before its application to a problem, because the algorithm is strongly effected by the control constants. In this research, the satellite mission scheduling algorithm is simulated with different crossover probability and mutation probability, which is major control constant of the genetic algorithm.
Reference Trajectory Analysis and Trajectory Control by Bank Angle for Re-Entry Vehicle
Cho, Kyeum-Rae,Lee, Dae-Woo The Korean Society of Mechanical Engineers 2002 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.16 No.6
The re-entry problem consists of guidance design and trajectory control. This paper summarizes the detailed relationships between the velocity, drag acceleration and altitude in determining reference trajectories. The computational issues are also addressed, and the performance of the proposed simple nonlinear control of a bank angle for the longitudinal/ lateral trajectory is demonstrated. In particular, the fixed bank angle methods that can reduce the drag acceleration errors at low-speeds are proposed. The importance of bank reversals with respect to the azimuth errors Is also elucidated.
Re-Entry Trajectory Tracking Via an Inverse Dynamics Method
Dae-Woo Lee,Kyeum-Rae Cho,Hui Van 대한기계학회 2004 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.18 No.9
Atmospheric Re-Entry guidance is divided as longitudinal and lateral. This paper proposes a longitudinal reference trajectory and control law using the inverse dynamics method with pseudo spectral Legendre method. Application of this method into Re-Entry problem forces a power of calculation time-reduction due to unnecessary of integration or any iteration as well as sufficient accuracy convergence. The used guidance scheme is time-to-go.
Optimal Structural Design for Flexible Space Structure with Control System Based on LMI
Park, Jung-Hyen,Cho, Kyeum-Rae The Korean Society of Mechanical Engineers 2002 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.16 No.1
A simultaneous optimal design problem of structural and control systems is discussed by taking a 3-D truss structure as an object. We use descriptor forms for a controlled object and a generalized plant because the structural parameters appear naturally in these forms. We consider a minimum weight design problem for structural system and disturbance suppression problem for the control system. The structural objective function is the structural weight and the control objective function is $H_{\infty}$ norm from the disturbance input to the controlled output in the closed-loop system. The design variables are cross sectional areas of the truss members. The conditions for the existence of controller are expressed in terms of linear matrix inequalities (LMI) By minimizing the linear sum of the normalized structural objective function and control objective function, it is possible to make optimal design by which the balance of the structural weight and the control performance is taken. We showed in this paper the validity of simultaneous optimal design of structural and control systems.
Reference Trajectory Analysis and Trajectory Control by Bank Angle for Re-Entry Vehicle
Dae Woo Lee,Kyeum Rae Cho 대한기계학회 2002 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.16 No.6
The re-entry problem consists of guidance design and trajectory control. This paper summarizes the detailed relationships between the velocity, drag acceleration and altitude in determining reference trajectories. The computational issues are also addressed, and the performance of the proposed simple nonlinear control of a bank angle for the longitudinal/ lateral trajectory is demonstrated. In particular, the fixed bank angle methods that can reduce the drag acceleration errors at low-speeds are proposed. The importance of bank reversals with respect to the azimuth errors is also elucidated.