Payload transportation in microgravity with single and multiple cooperative free-flyer robots

The use of free-flyer robots in space applications has been increasing in recent years. Several space agencies, such as NASA, DLR and JAXA, have at this moment, or intend to have, projects involving this type of vehicles. The increasing interest in these robots is largely motivated by the expansion of human presence beyond low earth orbit, to cislunar space and beyond. In particular, the envisioned Deep Space Gateway (DSG) will require autonomous robots performing logistics operations. This work presents a nonlinear model predictive control based method targeting a free-flyer robot in microgravity to perform 3 different tasks: waypoint navigation, single robot transportation, and multi-robot transportation. This controller is coupled with a trajectory generation method that provides feasible trajectory references to the controller, and is capable of handling confined spaces, composed by walls and obstacles, as well as control actuation limitations and system dynamics. All tests conducted in this work were obtained through realistic simulation based in ROS and Gazebo/RotorS.