Development of Structures and Methods for Safe On Orbit Robotic Assembly of Small Satellites

Abstract

While the advent of small satellites such as CubeSats have allowed for space to become quicker and easier to access, the turn-around time is still insufficient for rapid deployment. Example situations are replacing nodes in large constellations, time-sensitive science experiments, or disaster relief imaging. A solution can be found in on-orbit assembly. By flat packing a large quantity of snap-fit compatible boards for a plurality of CubeSats and assembling them on-orbit, time from conception to operation can be significantly lowered. Crucial to on-orbit robotic assembly is the design of the satellite. Traditional CubeSats, with rails, precise pin connectors, dense headers, and small wires, are difficult to assemble for all but the most advanced robots. Instead, this thesis discusses the design and testing of custom-made structures for assembly by a cartesian robot with an electromagnetic end-effector. These structural designs need to ensure consistent, repeatable, and safe assembly of satellites, both on the ground and on orbit. The requirements for such a system are examined with a Systems Theoretic Process Analysis, or STPA. Additionally, different types of compliant design features, such as sliding latches and chamfer overhangs, have their performance analyzed by performing repeated insertion tests. It is found that, with compliant designs, a cartesian robot can assemble the designed structure of eight boards and four rails in approximately four minutes.