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Jonathan P. How. Aoudé, Georges Salim Massachusetts Institute of Technology. Dept. of Aeronautics and Astronautics. Massachusetts Institute of Technology. Department of Aeronautics and Astronautics 2008-09-02T17:54:45Z 2008-09-02T17:54:45Z 2007 2007 http://hdl.handle.net/1721.1/42050 230816006 Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2007. This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. Includes bibliographical references (p. 143-149). The thesis 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 thesis also places emphasis on the importance of the initialization step in pseudospectral methods in order to decrease their computation times. It demonstrates the improvement that an initial guess based on an RRT planner brings to an optimal control problem solved using pseudospectral methods. Finally, this thesis presents the successful results of several reconfiguration maneuver experiments performed using the Synchronized Position Hold Engage and Reorient Experimental Satellites (SPHERES) hardware testbed onboard the International Space Station (ISS). The maneuvers were designed using two different two-stage algorithms presented in this work. It also discusses the lessons learned from these tests, and the recommendations to improve future ISS reconfiguration experiments. by Georges Salim Aoudé. S.M. 149 p. eng Massachusetts Institute of Technology M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. http://dspace.mit.edu/handle/1721.1/7582 Aeronautics and Astronautics. Two-stage path planning approach for designing multiple spacecraft reconfiguration maneuvers and application to SPHERES onboard ISS 2-stage path planning approach for designing multiple spacecraft reconfiguration maneuvers and application to Synchronized Position Hold Engage and Reorient Experimental Satellites onboard the International Space Station Thesis application/pdf false Publication unknown unknown <Publication xmlns="https://www.openaire.eu/cerif-profile/1.1/" id="92ab0461-f714-442d-a765-500673061a55"> <Type xmlns="https://www.openaire.eu/cerif-profile/vocab/COAR_Publication_Types">http://purl.org/coar/resource_type/c_1843</Type> <Language>eng</Language> <Title>Two-stage path planning approach for designing multiple spacecraft reconfiguration maneuvers and application to SPHERES onboard ISS</Title> <Subtitle>2-stage path planning approach for designing multiple spacecraft reconfiguration maneuvers and application to Synchronized Position Hold Engage and Reorient Experimental Satellites onboard the International Space Station</Subtitle> <PublishedIn> <Publication> </Publication> </PublishedIn> <PublicationDate>2007</PublicationDate> <Authors> <Author> <DisplayName>Aoudé, Georges Salim</DisplayName> <Affiliation> <OrgUnit> </OrgUnit> </Affiliation> </Author> </Authors> <Editors> </Editors> <Publishers> <Publisher> <DisplayName>Massachusetts Institute of Technology</DisplayName> <OrgUnit /> </Publisher> </Publishers> <License>http://dspace.mit.edu/handle/1721.1/7582</License> <Keyword>Aeronautics and Astronautics.</Keyword> <Abstract>The thesis 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 thesis also places emphasis on the importance of the initialization step in pseudospectral methods in order to decrease their computation times. It demonstrates the improvement that an initial guess based on an RRT planner brings to an optimal control problem solved using pseudospectral methods. Finally, this thesis presents the successful results of several reconfiguration maneuver experiments performed using the Synchronized Position Hold Engage and Reorient Experimental Satellites (SPHERES) hardware testbed onboard the International Space Station (ISS). The maneuvers were designed using two different two-stage algorithms presented in this work. It also discusses the lessons learned from these tests, and the recommendations to improve future ISS reconfiguration experiments.</Abstract> <Access xmlns="http://purl.org/coar/access_right" > </Access> </Publication>