Formation control and reconfiguration through synthetic imaging formation flying testbed (SIFFT)

The objective of the Synthetic Imaging Formation Flying Testbed (SIFFT) is to develop and demonstrate algorithms for autonomous centimeter-level precision formation flying. This technology helps to enable synthetic aperture imaging systems, especially when combined with second stage precision optical control systems. Preliminary tests have been conducted on SIFFT at the Flat Floor facility at NASA’s Marshall Space Flight Center (MSFC). The goal of the testing at MSFC was to demonstrate formation control of three “apertures” in an equilateral triangle and to reconfigure the formation by rotation and expansion of the triangle. Results were very successful and demonstrate the ability to position and reconfigure separate apertures. The final configuration was with three satellites floating. The two Follower satellites expand the formation with respect to the Master satellite, which executes a 10° rotation. This test was performed successfully under various initial conditions: initial Follower rotation, initial Follower drift, and initial significant position error of each Follower. Simple PID controllers were implemented to maintain position and attitude. Results show roughly 10cm steady state error and ±5cm precision. In addition, formation capturing technique, where satellites search for each other without prior knowledge of the position of the other satellites, is developed and demonstrated both on the 2D flat table and in the 3D International Space Station environment. Future work includes using a minimum set of beacons for estimation and implementing a search algorithm so satellites can acquire each other from any initial orientation.