Space systems design (spacecraft, satellites, space stations and their equipment)
Ghasem Heydari; Maryam Kiani; S. Hossein Pourtakdost; Mohammad Sayanjali
Volume 13, Issue 3 , September 2020, , Pages 25-38
Abstract
Halo orbits are of importance for observation and study of the space due to their specific characteristics including the orbital position and the periodic motion. In this regards, present paper has focused on optimal trajectory planning to transfer to halo orbits. To this aim, homotopy approach has been ...
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Halo orbits are of importance for observation and study of the space due to their specific characteristics including the orbital position and the periodic motion. In this regards, present paper has focused on optimal trajectory planning to transfer to halo orbits. To this aim, homotopy approach has been adopted for optimal trajectory design. This approach has improved the convergence rate and insensitivity of the problem to initial guess. The designed trajectory transfers a spacecraft orbiting the Earth to a Halo orbit around Lagrangian point L1 of the Earth-moon restricted three-body system. The propulsion system has been assumed to be low thrust with constant specific impulse. Homotopy approach has a broad domain of applicability and methods in which continuation method has been employed here among them. The optimal designed trajectory minimizes the fuel consumption via transforming solution of the minimum energy problem utilizing the homotopy approach. This approach simplifies solution of the complex problem of minimum fuel indeed.
recognition, evaluation, and detection of space radiation
Marjan Moghanipoor; Maryam Kiani; S. Hossein Pourtakdost; Amir Labibian
Volume 12, Issue 4 , December 2019, , Pages 91-102
Abstract
Temperature sensors have recently been proposed for attitude estimation (AE) of Low-Earth satellites. However, since half of the satellite surfaces do not receive any heat flux from the Sun, conduction occurs among the satellite surfaces. In this regard, the present study has focused on the effect of ...
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Temperature sensors have recently been proposed for attitude estimation (AE) of Low-Earth satellites. However, since half of the satellite surfaces do not receive any heat flux from the Sun, conduction occurs among the satellite surfaces. In this regard, the present study has focused on the effect of surfaces’ conduction as well as inner radiation on AE using temperature sensors. The nonlinear filter of Unsceted Kalman filter is adopted for AE, and the developed model to describe temperature rates is verified using Thermal Desktop and SINDA software. Monte Carlo simulations prove positive effect of the conduction on AE performance against negative role of the inner radiation.
Maryam Kiani; Amir Shakouri; S.H Pourtakdoust; Mohammad Sayanjali
Volume 11, Issue 1 , June 2018, , Pages 49-57
Abstract
A new strategy is presented for the optimal transfer of non-coplanar elliptical orbits based on sequential multi-Lambert trajectories. The proposed method tries to minimize the control effort during the orbit transfer. The main advantages of the proposed method include transfer between arbitrary initial ...
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A new strategy is presented for the optimal transfer of non-coplanar elliptical orbits based on sequential multi-Lambert trajectories. The proposed method tries to minimize the control effort during the orbit transfer. The main advantages of the proposed method include transfer between arbitrary initial and final orbits, utilizing desired number of impulses, and covering all possible transfer trajectories to achieve the target. The position and time instant of impulses are considered as the design variables which determine utilizing the well-known optimization method of pseudo-Newton. Performance of the proposed method is investigated and verified through some numerical simulations. It is also shown that the proposed method converges to the celebrated Hahmann’s maneuver in transfer between two coplanar orbital orbits.
M. Jafari Nadoushan; S. H. Pourtakdoust
Volume 3, Issue 1 , July 2010, , Pages 75-80
Abstract
Development of halo orbits and their associated invariant manifolds are investigated. Halo orbits play a fundamental role in complex space mission designs. In essence, halo orbits are periodic solutions of the restricted three body problem (R3BP) determined under specific initial conditions. In this ...
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Development of halo orbits and their associated invariant manifolds are investigated. Halo orbits play a fundamental role in complex space mission designs. In essence, halo orbits are periodic solutions of the restricted three body problem (R3BP) determined under specific initial conditions. In this paper, the symmetric property of the nonlinear R3BP governing differential equations is utilized in order to obtain the desired initial conditions. In this regard the differential correction technique and the state transition matrix are used to generate the halo orbits. The differential correction technique, based on the Newton method, is an effective tool for solving two point boundary value problems. In addition to generate the stable and unstable manifolds, the initial conditions are perturbed in the direction of Eigenvectors and the equations of motion are integrated for an arbitrary time interval.
S. H. Pourtakdoust; R. Moradi; R. Kamyar
Volume 2, Issue 2 , July 2009, , Pages 1-16
Abstract
In this work the coupled nonlinear problem of optimal spacecraft rendezvous and docking (RVD) is addressed. In most of the previous studies on the subject of optimal RVD, decoupling is presumed to exist between the trajectory translational and the attitude motions and hence the optimal coupled analysis ...
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In this work the coupled nonlinear problem of optimal spacecraft rendezvous and docking (RVD) is addressed. In most of the previous studies on the subject of optimal RVD, decoupling is presumed to exist between the trajectory translational and the attitude motions and hence the optimal coupled analysis has not been yet addressed properly. However there are circumstances where these two motions are in fact coupled and interdependent and one such situation is investigated and analyzed in this article. By utilizing thrusters for the translational control and reaction wheels for the attitude control, one can uncouple the translational and rotational control to a high degree of approximation. However it can be shown that due to even very small thrust misalignments, the uncoupled problem changes to a highly coupled one. In this article, the nonlinear rendezvous and docking problem is assumed to be coupled and its optimal fuel-trajectory closed loop solution is obtained using two approaches of local linearization and Gauss Pseudospectral methods. Therefore the designed controllers are able to handle the highly nonlinear coupled rendezvous and docking optimally in the presence of system uncertainties as well as environmental disturbances. The results of the two solution approaches and their pertinent control strategies are compared and the merits and weaknesses of each are fully analyzed. Finally, a sensitivity analysis is also performed that shows the effects of thrust misalignments levels on the final state diversions.
S. Hossein Pourtakdost; M. Fakhri; Nima Asadian
Volume 1, Issue 1 , September 2008, , Pages 1-10
Abstract
Current practical methods of pitch programming design for multi-stage launch and ballistic vehicles suffer from several deficiencies. For many applications they are often determined for various phases of ascent trajectory utilizing simplified dynamics that results in non-optimal trajectories. Trial-and-error ...
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Current practical methods of pitch programming design for multi-stage launch and ballistic vehicles suffer from several deficiencies. For many applications they are often determined for various phases of ascent trajectory utilizing simplified dynamics that results in non-optimal trajectories. Trial-and-error design techniques coupled with flight simulation usually results in a more accurate pitch program, but that may not satisfy all the required constraints simultaneously and is also very time consuming. In this study, an integrated design environment is developed which enables a novice designer to generate optimal pitch program for the whole part of the ascent trajectory while satisfying all the required flight path constraints as well as the final time boundary conditions. Since, the preset guidance program is naturally known as an open-loop steering program, this method utilizes optimal control theory using full nonlinear system state equations together with a functional performance index to determine the optimal steering command. Evaluation of the proposed technique is demonstrated through application on a typical two stage ballistic vehicle, for which the resulting trajectory fully satisfies all the flight related and final time constraints.
