Optimal Reconfiguration Maneuvers for Spacecraft Imaging Arrays in Multi-Body Regimes
- Paper number
IAC-07-C1.7.03
- Author
Ms. Lindsay Millard, Purdue University, United States
- Coauthor
Prof. Kathleen Howell, Purdue University, United States
- Year
2007
- Abstract
Sparse aperture telescope arrays may provide imaging capabilities far more powerful than any current monolithic imager. This imaging array design, however, incurs implementation challenges. Numerous tight inter-spacecraft positioning and system geometry constraints must be satisfied to assure successful imaging. But, a minimum expenditure of fuel and autonomous operation are also potential priorities. Much of the available research in formation flight applications focuses on Earth-orbiting configurations, where the influence of other gravitational perturbations can be safely ignored. However, interest in formations that evolve in the vicinity of the Sun-Earth libration points, e.g., planet-finders, has inspired new studies regarding formation keeping in these regimes. New developments in interferometric satellite formation control have been pursued, but only in limited scope. Consider applications to specific types of missions (including, for example, NASA’s TPF-Occulter concept). Mission requirements include a baseline scenario in which multiple spacecraft collect observations and, subsequently, reorient over some specified time interval. The formation is assumed to move along a libration point orbit in a multi-body regime. In the current study, a method is developed to identify minimum cost maneuvers. Given the initial positions of the spacecraft in a formation, a specified maneuver time, and the final desired position, a two-point boundary value problem is solved to determine a minimum cost trajectory. Previous studies in this regime assume that the spacecraft are moving in free space; the only forces acting on the system are control forces. However, this analysis incorporates natural dynamics in the optimal maneuver design and problem formulation. The two-point boundary problem is solved using a Newton-Raphson numerical algorithm. Because of sensitivities in the multi-body model, the initial conditions in the algorithm must be accurate to within some small tolerance to facilitate convergence. Thus, adequate initial conditions are determined based on knowledge of the dynamical phase space surrounding halo orbits in the three-body problem. Also, the trajectory path may be segmented for extended-time maneuvers. By segmenting the path within the optimization problem formulation, sensitivities in the dynamical model may be mitigated. Optimal maneuver trajectories are identified and implemented for differing mission scenarios. The control effort required for these maneuvers is compared to more traditional maneuver control methods such as impulsive targeting, feedback linearization, and linear quadratic regulators. The image is simulated with varying mission parameters, including: number of satellites, distance to the object of interest, mission duration, time between maneuvers, and maximum formation baseline.
- Abstract document
- Manuscript document
IAC-07-C1.7.03.pdf (🔒 authorized access only).
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