1,721,003 research outputs found
Optical-aided, autonomous and optimal space rendezvous with a non-cooperative target
No full textPerforming rendezvous in close-proximity of a non-cooperative target is a challenging task, especially if certain performance requirements have to be met. When maneuvering in hazardous scenarios in order to accomplish either refuelling, inspection, repair or dismissal tasks, optimality and safety are relevant aspects to be sought. Additionally, autonomy is essential in unmanned missions. All these aspects can be achieved through purposely intended Guidance Navigation and Control (GNC) architectures. Optimality is obtained by means of the guidance system, that is by a proper optimal trajectory calculation. Safety and accuracy are guaranteed by evaluation of target's relative pose and shape, which is exploited by the navigation system. Among all the possible choices, optical hardware is becoming widely studied for its high accuracy and capability to reconstruct three-dimensional properties of the observed scene. The present work investigates the reciprocal influences between the guidance and navigation subsystems, putting higher focus on how the performance of an optimal rendezvous maneuver with a non-cooperative target can be influenced by the accuracy reached in the pose and shape estimation process. To this purpose, the chaser, or maneuvering spacecraft is considered to be equipped with a single camera and a distance sensor, as this architecture both provides high accuracy and meets mass, power and volume requirements to be implemented on-board a small platform. An algorithm including the optimization process and a purposely built filter, capable of receiving images as inputs and providing evaluation of target's relative pose and shape as output, is implemented and tested in several different scenarios to validate the feasibility of the maneuver
Quantum-inspired diffusion Monte Carlo optimization algorithm applied to space trajectories and attitude maneuvers
No full textIn this work, an algorithm for solving optimization problems is proposed, inspired by a computational method employed in Quantum Mechanics: the Diffusion Monte Carlo method, commonly used for the computation of ground states of many-particle systems. The optimization problem is re-formulated as the problem of sampling the ground state wave function of a particle subject to a potential based on the function to be minimized. The algorithm is applied to problems in space trajectory and spacecraft attitude maneuvers optimization, the first application is to the problem of transfer between circular orbits, the results obtained are compared to the results from the literature,
then it is applied to the problem of rendezvous with the asteroid Pallas, and finally to the optimization of an attitude maneuver in the presence of several constraints, and the obtained results are compared to two widely used methods: Particle Swarm Optimization and Differential Evolution algorithms. The algorithm is of simple implementation, and the numerical results show better performance than the comparison methods in the considered problems
Quantum-inspierd diffusion monte carlo optimization algorithm applied to space trajectories
No full textIn this work, an algorithm for optimization is proposed, inspired by the principles of Quantum Mechanics. The algorithm is based on the Diffusion Monte Carlo method, commonly used for the computation of ground states of many-particles systems. The optimization problem is reconducted to sampling the ground state wave function of a particle subject to a potential based on the function to be minimized. The algorithm is applied to the problem of transfer between circular orbits and compared to the results in the literature. Then it is applied to the problem of rendezvous with the asteroid Pallas and compared to the results of Particle Swarm Optimization algorithm
Nonlinear model predictive control leveraging quantum-inspired optimization in the three body problem with uncertainty
No full textThe optimization and control of spacecraft trajectories in presence of uncertainties and unmodeled disturbances
represents a challenging problem. Future missions would benefit from robust control techniques to compute
their trajectory in a complex, nonlinear environment and in presence of stochasticity. In this work the
Stochastic Optimal Control problem in the Circular Restricted Three Body Problem is addressed and a method
is proposed based on Nonlinear Model Predictive control (NMPC). This method presents the challenge of
solving a nonlinear optimization problem on-board. A Quantum-inspired meta-heuristic optimization algorithm
is tested in this context: the Diffusion Monte Carlo (DMC) method is based on a numerical techniques used in
Quantum Mechanics, adapted to solve optimization problems. The NMPC with DMC is implemented, taking
into account an estimate of the computational time required through the introduction of delayed actuation of
the control. Two applications are presented featuring transfer trajectories between planar periodic orbits in the
vicinity of the Moon; the proposed method proved able to successfully generate trajectories when disturbance
accelerations and uncertain initial conditions are present
Design of Mars global longitudinal coverage constellation leveraging resonant and periodic orbits in Mars-Phobos-Deimos system
No full textOver the last decades, the exploration of Phobos and Deimos has acquired relevance from both scientific and human missions standpoint.
Both moons can play a key role on supporting the Martian Exploration program improving teleoperation capabilities and infrastructure
support. The purpose of this work is to propose a different approach to the problem of global longitudinal coverage of Mars,
exploiting the characteristic of natural satellites of the planet itself. The proposed constellation can be an alternative to the Mars Areostationary
Orbit (MAO), in fact, three satellites equally spaced at Deimos height are enough to provide global longitudinal coverage,
with a reduced cost. The main source of perturbation at areostationary height is due to the second degree, second order sectorial harmonic
of Mars gravitational field (J2;2), which requires high maintenance cost for an equivalent configuration in MAO. By leveraging
Lyapunov orbits in the Mars-Deimos perturbed Three Body Problem, it’s possible to achieve long term stable orbits with lower cost,
as well as ballistic orbits with bounded variations. The characteristics and the performance of the constellation are analyzed, as well
as the transfer orbits between the Mars-Deimos Lagrange points leveraging resonant orbits. The possibility of placing an extra satellite
in an orbit around Phobos with the purpose of increasing performance is also detailed, as well as the transfer trajectory from the Deimos
L3 point to a DRO orbit around Phobo
Wrinkling analysis for small solar-photon sails: an experimental and analytic approach for trajectory design
No full textA good model of solar-radiation pressure induced thrust is one of the key points in sailcraft trajectory design. The sail membrane’s local topographic deformations, i.e. wrinkles and creases, are among the main aspects that such a model should include. We have analyzed the influence of wrinkles/creases, as a whole, by measuring the related deformations on small samples of sail membrane, 2.5 lm thick, consisting of CP1 and physical-vapor-deposition Aluminum. Experimental outcomes from our laboratory facility have been processed, statistically investigated, and inserted into the lightness vector formalism. We have used such formalism for accurate sailcraft trajectory computation via a non-ideal reflection sail thrust model. Finally, we computed the deviations of wrinkled-sail sailcraft final orbital states with respect to the no-wrinkle sail final orbital ones for a circular to circular 2D inward transfer. The radii of the orbits are 1 AU and the semi-major axis of Mercury, respectively. It appears that sail wrinkles and creases are no longer negligible in the sailcraft trajectory design
A ground track-based approach to design satellite constellations
No full textFollowing an approach based on ground track analysis, original and compact relationships which permit the construction of ground track patterns and the determination of satellite arrangements able to generate appropriate track distance and revisit frequency over a given area are presented. These equations are valid in the general case of elliptical orbit and can easily be implemented in computer codes devoted to the design of single and multi-plane satellite constellations
Coronal Mass Ejection early-warning mission by solar-photon sailcraft
No full textA preliminary investigation of the early warning of solar storms caused by Coronal Mass Ejection has been carried out. A long warning time could be obtained with a sailcraft synchronous with the Earth-Moon barycenter, and stationed well below the L1 point. In this paper, the theory of heliocentric synchronous sailcraft is set up, its perturbed orbit is analyzed, and a potential solution capable of providing an annual synchrony is carried out. A simple analysis of the response from a low-mass electrochromic actuator for the realization of station-keeping attitude maneuvers is put forwards, and an example of propellantless re-orientation maneuver is studied
Selecting optimal inspection trajectories for target observation
No full textA challenging aspect regarding proximity operations such as on-orbit servicing, refuelling and dismissal is the selection of optimal trajectories. The path should be conveniently followed by making use of sensors and actuators available on-board Optical hardware has been lately demonstrated to be both accurate and reliable for determining pose estimation in space proximity operations. Nevertheless, when passive cameras are used, accuracy is achieved through clear images which are obtained if the target is in favourable relative illumination conditions. The goal of this work is to design an optimal docking trajectory to an uncontrolled, non-cooperative, free-tumbling satellite. This trajectory should satisfy initial and final constraints, avoid collisions with the target and be optimal in terms of propellant consumption and relative sunlight viewing conditions. To this aim, an inverse optimization method based on polynomial parameterization of the trajectory is used inside a multi-objective genetic algorithm. The effect of the favourable illumination conditions on the camera measurements noise will be discussed. A comparison is carried out with a trajectory obtained from a single objective optimization. The signicant inclusion of the constraint about illumination conditions, with relevant effect on the camera measurements noise, is discussed and evaluated
Solar sail H-reversal trajectory: a review of its advances and applications
No full textThe set of the orbital angular-momentum reversal, or H-reversal, sailcraft trajectory was born as a type of unconventional precursor interstellar mission trajectory by using highperformance solar sails. Starting from an outline of the H-reversal sail trajectory, this paper mainly focuses on the 2D reversal-mode solution to the general solar-photon sail motion equations. The feasible region for H-reversal trajectories in fixed sail attitude angles is illustrated. Some interesting applications of the H-reversal trajectory are presented in detail to show its advantages. As a special case, a precursor interstellar probe can be delivered with a constant sail orientation in the H-reversal trajectory to be compared with the direct-motion sail flyby of the Sun. Of importance are the heliocentric periodic orbits in double H-reversal modes, obtained via both fixed and time-varying sail attitude angles. Two more applications involving H-reversal trajectories are discussed in terms of asteroid deflection and transfer trajectory to rectilinear orbits. Finally, some items of the mathematics behind the 3D motion-reversal trajectories are summarized
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