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A Time-Optimal Space Station Reboost Guidance Strategy*
Renjith R. Kumar** and Hans Seywald***
Abstract
A closed-loop guidance strategy for time and fuel optimal reboost of Space Station Freedom is discussed in this paper. The reboost maneuver is formulated as an Optimal control problem rather than a parameter optimization problem, the parameters being the thrust switching times. In the present approach the thrust switching structure need not be prescribed a priori to solve the resulting two point boundary value problem. Non-optimality of singular control or intermediate thrust is proved by utilizing the second order Kelley condition or the Generalized Legendre-Clebsch condition. Only
a few sets of initial co-states and time-to-go guess values need to be stored on-board for a wide range of reboost scenarios.
*This work was completed under contract NAS1-18935 with Spaco Station Freedom Oftice at NASA Langley Research Center.
**Supervising Engineer. Analytical Mechanics Associates, Inc., 17 Research Drive, Hampton, Virginia 23666. Member AIAA
***Senior Project Engineer. Analytical Mechanics Associates, Inc., 17 Research Drive, Hampton, Virginia 23666.Member AIAA.