Aligning Civil and Private Interests towards Space Exploration Breakthroughts: Implementation Issues for NASA's Centennial Challenges Program
- Paper number
IAC-04-IAA.5.13.2.04
- Author
Mr. Brant Sponberg, National Aeronautics and Space Administration (NASA)/Headquarters, United States
- Year
2004
- Abstract
The majority of existing spacecraft in operation fall into the categories of large (>1000kg) through medium-sized (500-1000kg) to mini (100-500kg). All of these spacecraft have a volume and computational capacity that allows for complex means of control and decision making. Recently the drive has been toward reducing spacecraft mass which has introduced new constraints on the computational capacity that will be available for control and decision making algorithms. Radiation damage also is a key issue for smaller on-board processors. The aim of this paper is to present a new method for decision making algorithms that can be introduced to smaller micro (10-100kg) or nano (1-10kg) spacecraft. The key underlying concept is to use Modern Dynamic Systems Theory to generate provable algorithms for on-board use.
Coupled differential equations can be generated to define many dynamical systems and can be manipulated to achieve control of the system. Such analytic-based algorithms can be mathematically validated and shown to be very computationally efficient. In this paper the concept of hetero-clinic cycles is exploited to transition between control states. A hetero-clinic cycle is a collection of solution trajectories that connects sequences of equilibria, periodic solutions or chaotic invariant sets via saddle-sink connections.
To demonstrate this dynamical systems approach, a simple micro-spacecraft orbital model with a hetero-clinic cycle action selection algorithm has been developed. The model involves a single satellite in orbit around the earth with three states that in turn correspond to the action that it may perform depending on those states at any instant in time (record data, down-link data and battery charging). State space mappings resulting from the simulation are presented along with an analysis of the action selection. The results from this model demonstrate the use of modern dynamic systems theory to generate provable control algorithms.
Keywords: autonomy, dynamic systems theory, hetero-clinic cycles, micro-spacecraft
- Abstract document