Manhole Detection and Traversal for Exploration of Ballast Water Tanks using Micro Aerial Vehicles

This paper presents a method for the autonomous exploration of multiple compartments of a Ballast Water Tank inside a vessel using Micro Aerial Vehicles. Navigation across the compartments of ballast tanks often requires the robot to pass through narrow cross-section "manholes" (e.g., 0.8x0.6m). Hence, this work presents an algorithm to explicitly detect and localize such manholes using 3D LiDAR data and a strategy to reliably navigate through them to enable autonomous exploration of multiple compartments of the tank. Two ablation studies are presented analyzing the effective 3D space with respect to the manhole in which reliable detection takes place. Furthermore, the method is evaluated onboard a collision-tolerant aerial robot in two autonomous exploration experiments in relevant mock-up scenarios.