Hybrid Planning to Minimize Platform Disturbances during In-orbit Assembly Tasks

In-orbit space assembly has been proposed as a method to overcome the obstacles for deployment of large spatial structures. To make such assemblies economically feasible, they must rely on robotic arms to perform the required manipulation actions. The operations with the robotic arm inevitably affect the attitude and orientation of the spacecraft. This influence is well understood for simple trajectories; however, assembly sequences for full structures require multiple repetitive motions, with and without load, which significantly affect the attitude and orbital control of the satellite. This paper analyzes such perturbations for a complex assembly task, the construction of the primary mirror for a space telescope, using a hybrid planner with two levels: a low level that considers individual motions of the robotic arm, and a high level that generates the overall assembly sequence while minimizing the perturbations created on the attitude control system. The method effectively minimizes perturbations during orbital assembly tasks, therefore minimizing fuel or energy consumption in the spacecraft.