Decentralized Topological Mapping for Multi-robot Autonomous Exploration under Low-Bandwidth Communication

This paper concerns a mapping framework for multi-robot exploration of underground environments with only very limited communication available. We focus on multi-robot map building and coordination to explore large areas with real-time planning to long distances. The considered communication can broadcast only 100B/s, and therefore, we propose coordination planning using two terrain models. The first model is a dense 3D map built by each robot individually to identify explorable places and generate detailed plans to avoid un-traversable areas. The second model is a global topological map built in a decentralized manner by exchanging tiny 12B packets between the robots. The feasibility of the proposed approach has been verified in the real-world autonomous exploration mission and various multi-robot scenarios inspired by a virtual cave circuit of the DARPA Subterranean Challenge while adapting two different decentralized coordination strategies.