5,605 research outputs found
Rational physical agent reasoning beyond logic
The paper addresses the problem of defining a theoretical physical agent framework that satisfies practical requirements of programmability by non-programmer engineers and at the same time permitting fast realtime operation of agents on digital computer networks. The objective of the new framework is to enable the satisfaction of performance requirements on autonomous vehicles and robots in space exploration, deep underwater exploration, defense reconnaissance, automated manufacturing and household automation
FIRI - a Far-Infrared Interferometer
Half of the energy ever emitted by stars and accreting objects comes to us in
the FIR waveband and has yet to be properly explored. We propose a powerful
Far-InfraRed Interferometer mission, FIRI, to carry out high-resolution imaging
spectroscopy in the FIR. This key observational capability is essential to
reveal how gas and dust evolve into stars and planets, how the first luminous
objects in the Universe ignited, how galaxies formed, and when super-massive
black holes grew. FIRI will disentangle the cosmic histories of star formation
and accretion onto black holes and will trace the assembly and evolution of
quiescent galaxies like our Milky Way. Perhaps most importantly, FIRI will
observe all stages of planetary system formation and recognise Earth-like
planets that may harbour life, via its ability to image the dust structures in
planetary systems. It will thus address directly questions fundamental to our
understanding of how the Universe has developed and evolved - the very
questions posed by ESA's Cosmic Vision.Comment: Proposal developed by a large team of astronomers from Europe, USA
and Canada and submitted to the European Space Agency as part of "Cosmic
Vision 2015-2025
Two-Stage Path Planning Approach for Designing Multiple Spacecraft Reconfiguration Maneuvers
The paper presents a two-stage approach for designing optimal reconfiguration maneuvers for multiple spacecraft. These maneuvers involve well-coordinated and highly-coupled motions of the entire fleet of spacecraft while satisfying an arbitrary number of constraints. This problem is particularly difficult because of the nonlinearity of the attitude dynamics, the non-convexity of some of the constraints, and the coupling between the positions and attitudes of all spacecraft. As a result, the trajectory design must be solved as a single 6N DOF problem instead of N separate 6 DOF problems. The first stage of the solution approach quickly provides a feasible initial solution by solving a simplified version without differential constraints using a bi-directional Rapidly-exploring Random Tree (RRT) planner. A transition algorithm then augments this guess with feasible dynamics that are propagated from the beginning to the end of the trajectory. The resulting output is a feasible initial guess to the complete optimal control problem that is discretized in the second stage using a Gauss pseudospectral method (GPM) and solved using an off-the-shelf nonlinear solver. This paper also places emphasis on the importance of the initialization step in pseudospectral methods in order to decrease their computation times and enable the solution of a more complex class of problems. Several examples are presented and discussed
Manoeuvre Planning Architecture for the Optimisation of Spacecraft Formation Flying Reconfiguration Manoeuvres
Formation flying of multiple spacecraft collaborating toward the same goal is fast
becoming a reality for space mission designers. Often the missions require the spacecraft to
perform translational manoeuvres relative to each other to achieve some mission objective.
These manoeuvres need to be planned to ensure the safety of the spacecraft in the formation
and to optimise fuel management throughout the fleet. In addition to these requirements is it
desirable for this manoeuvre planning to occur autonomously within the fleet to reduce
operations cost and provide greater planning flexibility for the mission. One such mission that
would benefit from this type of manoeuvre planning is the European Space Agency’s
DARWIN mission, designed to search for extra-solar Earth-like planets using separated
spacecraft interferometry.
This thesis presents a Manoeuvre Planning Architecture for the DARWIN mission. The
design of the Architecture involves identifying and conceptualising all factors affecting the
execution of formation flying manoeuvres at the Sun/Earth libration point L2. A systematic
trade-off analysis of these factors is performed and results in a modularised Manoeuvre
Planning Architecture for the optimisation of formation flying reconfiguration manoeuvres.
The Architecture provides a means for DARWIN to autonomously plan manoeuvres during
the reconfiguration mode of the mission. The Architecture consists of a Science Operations
Module, a Position Assignment Module, a Trajectory Design Module and a Station-keeping
Module that represents a multiple multi-variable optimisation approach to the formation
flying manoeuvre planning problem. The manoeuvres are planned to incorporate target
selection for maximum science returns, collision avoidance, thruster plume avoidance,
manoeuvre duration minimisation and manoeuvre fuel management (including fuel
consumption minimisation and formation fuel balancing). With many customisable variables
the Architecture can be tuned to give the best performance throughout the mission duration.
The implementation of the Architecture highlights the importance of planning formation
flying reconfiguration manoeuvres. When compared with a benchmark manoeuvre planning
strategy the Architecture demonstrates a performance increase of 27% for manoeuvre
scheduling and fuel savings of 40% over a fifty target observation tour.
The Architecture designed in this thesis contributes to the field of spacecraft formation
flying analysis on various levels. First, the manoeuvre planning is designed at the mission
level with considerations for mission operations and station-keeping included in the design.
Secondly, the requirements analysis and implementation of Science Operation Module
represent a unique insight into the complexity of observation scheduling for exo-planet
analysis missions and presents a robust method for autonomously optimising that scheduling.
Thirdly, in-depth analyses are performed on DARWIN-based modifications of existing
manoeuvre optimisation strategies identifying their strengths and weaknesses and ways to
improve them. Finally, though not implemented in this thesis, the design of a Station-keeping
Module is provided to add station-keeping optimisation functionality to the Architecture
Space, the new frontier
Space program - high thrust boosters with greater payload capabilities, superior guidance and control, and astronaut trainin
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