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Development of a Reachability Analysis Algorithm for Space Applications

Arslantas, Yunus (2017) Development of a Reachability Analysis Algorithm for Space Applications. Dissertation, Universität Bremen.

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In the last decades developments in space technology paved the way to more challenging missions like asteroid mining, space tourism and human expansion into the Solar System. These missions require difficult tasks such as real-time capable guidance schemes for re-entry, landing on celestial bodies and implementation of large angle maneuvers for spacecraft. There is a need for an analysis tool to increase the robustness and success of these missions. Reachability analysis contributes to this requirement by obtaining the set of all achievable states for a dynamical system starting from an initial condition with given admissible control inputs of the system. In this study, an optimal control based reachability analysis algorithm is developed for evaluating the performance of the guidance and control methods for space missions considering the desired performance index. The developed method considers a soft-landing problem for a Moon mission as the case study, and attainable area of the lander as the performance index. The method computes feasible trajectories for the lunar lander between the point where the terminal landing maneuver starts and points that constitutes the candidate landing region. The candidate landing region is discretized by equidistant points on a two dimensional plane, i.e. in downrange and crossrange coordinates, and for each grid point a distance function is defined. This distance function acts as an objective function for a related optimal control problem (OCP). Each infinite dimensional OCP is transcribed into a finite dimensional Nonlinear Programming Problem (NLP) by using Pseudo-Spectral Methods (PSM). The NLPs are solved using available tools to obtain feasible trajectories and approximated reachable sets with information about the states of the dynamical system at the grid points. The proposed method approximates reachable sets of the lander with propellant-to-reach and time-to-reach cost by solution of NLPs. A polynomial-based Apollo guidance scheme is used to compare the results for the developed method. The coefficients that define the position of the lander are obtained by solving a series of explicit equations for the given initial and final states. A model inversion based PD controller is designed to track the generated trajectory. Feasible solutions that satisfy safe landing conditions are filtered and the results are compared for the two different approaches.

Item URL in elib:https://elib.dlr.de/116338/
Document Type:Thesis (Dissertation)
Title:Development of a Reachability Analysis Algorithm for Space Applications
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Arslantas, YunusUNSPECIFIEDhttps://orcid.org/0000-0001-9924-2250UNSPECIFIED
Date:20 June 2017
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In ISI Web of Science:No
Number of Pages:153
Keywords:reachable sets, optimal control, lunar landing
Institution:Universität Bremen
Department:Fachbereich Produktionstechnik
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Space System Technology
DLR - Research area:Raumfahrt
DLR - Program:R SY - Space System Technology
DLR - Research theme (Project):R - Projekt ATON (old)
Location: Bremen
Institutes and Institutions:Institute of Space Systems > Navigation and Control Systems
Institute of Space Systems > Systems Enabling Technologies
Deposited By: Theil, Dr.-Ing. Stephan
Deposited On:30 Nov 2017 12:48
Last Modified:31 Jul 2019 20:13

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