Analysis for robotic assembly of large flexible space structures

Abstract

Space solar power is a renewable, environment-friendly alternative to satisfy future terrestrial power needs. Space solar power stations will need to have large dimensions (on the order of hundreds of meters) to be able to collect enough power to make them cost effective. It will be infeasible to transport these large structures, fully assembled, from earth to space, or use human astronauts for their construction in space, leaving robotic assembly as the only viable option. The focus of the current work is to identify potential challenges to the large structure assembly process in space and develop methods to address them. One of the major causes of failure in the assembly process would be dimensional mismatch between the two structures to be joined. The first part of this thesis analyses the static and dynamic effects on a typical large space structure using finite element models and predicts the deformation that the structure will undergo due to thermal and vibration effects in space. Forced assembly methods using cooperative robots are developed to compensate for these dimensional errors. The second part of the thesis deals with the application of forced assembly methods to representative assembly scenarios. The scenarios are categorized based on the nature of the deformation involved. The differences between the use of thrusters and manipulators by robots are discussed and assembly plans are developed for each scenario using either or both types of actuators. A genetic algorithm based planner is developed and implemented to optimize the assembly process within the limits of the assumptions made.