Safety Constrained Free-Flyer Path Planning at the International Space Station

Abstract

A path-planning tool is presented to generate safe trajectories from an initial docking release, to a specified observation point, and back to docking for a small free-flying robot camera around the International Space Station. The tool makes use of ellipse of safety trajectories to enforce long-term passive safe requirements in the presence of differential air drag during the fly around phases of the maneuver during transfer between the docking port and observation point. Short-term passive safety (2-3 orbits) is also maintained during all station-keeping and approach maneuvers by checking the safety of the observation point at the initial planning stage, and through the use of precalculated velocities profiles along the r-bar forced motion approaches to the observation point and docking. The observation phase of the mission is enhanced through the use of artificial Laplace potential functions within a constrained volume, to allow for limited maneuvering close to the observation point enabling the available view to be translated and rotated.