Nonlinear trajectory optimization with path constraints applied to spacecraft reconfiguration maneuvers

Future space assembly and science missions (e.g., Terrestrial Planet Finder) will typically require complex reconfiguration maneuvers involving well coordinated 6 DOF motions of the entire fleet of spacecraft. The motions must also satisfy constraints such as collision avoidance and pointing restrictions on some of the instruments. This problem is particularly difficult due to the nonlinearity of the attitude dynamics and the non-convexity of some of the constraints. The coupling of the positions and attitudes of the N spacecraft by some of the constraints adds a significant complication because it requires that the trajectory optimization be solved as a single 6N DOF problem. This thesis presents a method to solve this problem by first concentrating on finding a feasible solution, then developing improvements to it. The first step is posed as a path planning problem without differential constraints and solved using Rapidly-exploring Random Trees (RRT's). The improvement step is posed as a feasible nonlinear optimization problem and solved by an iterative optimization similar to a sequential linear programming method. The primary contribution of the thesis is an improvement to the basic RRT algorithm that replaces the connection step with a more complex function that takes into account local information about the constraints. Two functions are proposed, one based on artificial potential functions, and another based on a random search. The results show that the new RRT with either of these connection functions is faster and more reliable for a difficult sample problem.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Aeronautics and Astronautics.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2005

Author dc:creator

• García, Ian Miguel

Advisor dc:contributor.advisor

• Jonathan P. How.

• Aeronautics and Astronautics.

Statement dc:rights

• 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.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/32448

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/32448