• Journal of Astronomy and Space Sciences
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• 제24권4호
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• pp.315-326
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• 2007

최근에 제안된, 이웃하는 타원 궤도의 상대운동에 대한 몇 가지 양함수형 해를 분석하였다. 이 해를 이용한 상대운동 결과를 일반 선형화 운동 방정식의 해석적 해와 비교했다. 수치계산 결과를 위한 초기 조건은 Hill-Clohessy-Wiltshire(HCW) 운동방정식에 의한 해의 역함수로 구했다. 기준 궤도의 차이에도 불구하고 상대적으로 작은 이심률의 궤도 일 경우에는 타원 상대운동 궤도와 원 상대운동 궤도의 결과는 근접했다. 주위성의 궤도가 상대적으로 큰 이심률을 가질 경우에는, 기본 궤도로 원 궤도를 이용하는 HCW 운동방정식은 다른 타원 상대운동 궤도 방정식의 해보다 상대적으로 큰 오차를 갖는다.

• Journal of Astronomy and Space Sciences
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• 제25권3호
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• pp.255-266
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• 2008

The current paper presents application of a new analytic solution in general relative motion to spacecraft formation flying in an elliptic orbit. The calculus of variations is used to analytically find optimal trajectories and controls for the given problem. The inverse of the fundamental matrix associated with the dynamic equations is not required for the solution in the current study. It is verified that the optimal thrust vector is a function of the fundamental matrix of the given state equations. The cost function and the state vector during the reconfiguration can be analytically obtained as well. The results predict the form of optimal solutions in advance without having to solve the problem. Numerical simulation shows the brevity and the accuracy of the general analytic solutions developed in the current paper.

• International Journal of Aeronautical and Space Sciences
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• 제15권1호
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• pp.82-90
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• 2014

In this paper, the effect of Lorentz force on the stability of attitude orientation of a charged spacecraft moving in an elliptic orbit in the geomagnetic field is considered. Euler equations are used to derive the equations of attitude motion of a charged spacecraft. The equilibrium positions and its stability are investigated separately in the pitch, roll and yaw directions. In each direction, we use the Lorentz force to identify an attitude stabilization parameter. The analytical methods confirm that we can use the Lorentz force as a stabilization method. The charge-to-mass ratio is the main key of control, in addition to the components of the radius vector of the charged center of the spacecraft, relative to the center of mass of the spacecraft. The numerical results determine stable and unstable equilibrium positions. Therefore, in order to generate optimum charge, which may stabilize the attitude motion of a spacecraft, the amount of charge on the surface of spacecraft will need to be monitored for passive control.