Return-to-base navigation of robotic swarms in Mars exploration using DoA estimation

In Mars exploration tasks, robotic swarms containing multiple autonomous units are efficient and robust against hazards in the mission. However, when the swarm travels significantly far away from the base, it is not sufficiently reliable to use the local map generated during the exploration alone to return. We propose a return-to-base navigation system for swarm exploration tasks using a radio link from the base station. With intra-swarm links, a swarm can be controlled into a coplanar formation and cooperatively determine the relative position. Then the swarm exploits the difference of phase measurements for distinct swarm elements to estimate the direction of arrival (DoA). The estimation of directions is shown to be reliable to guide the swarm back to the base.