MS thesis abstract - Radcliffe, Andrew

Author:	Radcliffe, Andrew
Degree:	Masters of Science
SERC #:	7-02
File type:	PDF, 1332 kB
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A Real-Time Simulator for the SPHERES Formation Flying Satellites Testbed

A software simulator for the SPHERES formation flight testbed, the GFLOPS SPHERES Simulator (GSS), has been developed. The Synchronized Position, Hold, Engage, and Reorient Experimental Satellites (SPHERES) testbed consists of three miniature spacecraft (or SPHERES), each with their own power, avionics, navigation, communications, and propulsion. These spacecraft will operate inside the International Space Station to test formation flying, autonomy, and autonomous rendezvous and docking algorithms. The GSS runs on the Generalized FLight Operations Processing Simulator (GFLOPS), a real-time embedded hardware testbed for the simulation of distributed space systems. SPHERES flight code can be run in the simulator to test the performance of guest investigator algorithms. The simulator models the characteristics of SPHERES hardware, including thrusters and metrology sensors, and simulates the dynamics of the spacecraft. Features include the ability to simulate SPHERE-SPHERE and SPHERE-wall collisions, as well as docking between SPHERES. A 3-D viewer allows users to monitor the motion of SPHERES within the test space and log the results for later playback. A command window allows users to view telemetry from the units and send them commands. Methods of measuring flight code processor utilization are discussed. Results are presented from sample simulations that demonstrate the capabilities of the simulator. Simulations include a leader-follower control architecture, a SPHERE-SPHERE collision, passive docking, and cooperative docking. Suggestions are given for future improvements to the simulator.