Long Duration Inspection of GNSS-Denied Environments with a Tethered UAV-UGV Marsupial System

TL;DR

This work tackles the UAV endurance bottleneck in GNSS-denied inspection tasks by introducing a tethered marsupial system that powers a UAV from a ground vehicle. It combines a hardware platform (UGV/UAV/tether) with a ROS-based software stack that includes Direct LiDAR Localization (DLL) and a tether-aware planning framework built on RRT* and nonlinear optimization, enabling safe, cooperative autonomy. Field tests across three buildings demonstrate flight durations exceeding two hours, centimeter-level localization accuracy, and autonomous inspection capabilities, with all data released for reproducibility. The approach offers a practical, modular solution to extend UAV endurance and expand inspection capabilities in challenging environments, while outlining avenues for further enhancements such as continuous coordination, outdoor deployments, and sensor modularity.

Abstract

Unmanned Aerial Vehicles (UAVs) have become essential tools in inspection and emergency response operations due to their high maneuverability and ability to access hard-to-reach areas. However, their limited battery life significantly restricts their use in long-duration missions. This paper presents a tethered marsupial robotic system composed of a UAV and an Unmanned Ground Vehicle (UGV), specifically designed for autonomous, long-duration inspection tasks in Global Navigation Satellite System (GNSS)-denied environments. The system extends the UAV's operational time by supplying power through a tether connected to high-capacity battery packs carried by the UGV. Our work details the hardware architecture based on off-the-shelf components to ensure replicability and describes our full-stack software framework used by the system, which is composed of open-source components and built upon the Robot Operating System (ROS). The proposed software architecture enables precise localization using a Direct LiDAR Localization (DLL) method and ensures safe path planning and coordinated trajectory tracking for the integrated UGV-tether-UAV system. We validate the system through three sets of field experiments involving (i) three manual flight endurance tests to estimate the operational duration, (ii) three experiments for validating the localization and the trajectory tracking systems, and (iii) three executions of an inspection mission to demonstrate autonomous inspection capabilities. The results of the experiments confirm the robustness and autonomy of the system in GNSS-denied environments. Finally, all experimental data have been made publicly available to support reproducibility and to serve as a common open dataset for benchmarking.

Figures (17)

• Figure 1: Our marsupial system performing autonomous inspection tasks in two buildings with structural damage in the University Pablo de Olavide (UPO), Seville (Spain). (a) Detail of the UAV at the abandoned thermal station (Scenario 2). (b) Tethered marsupial system at the old theater building (Scenario 3).
• Figure 2: Marsupial system, UAV tied to UGV. (a) Detail of the UGV equipped with the auxiliary structure that stores the systems of the marsupial configuration. (b) Marsupial system in an initial position before the experiment.
• Figure 3: Basic ARCO UGV from IDMind with its onboard batteries.
• Figure 4: M210 UAV and its additional onboard systems.
• Figure 5: (a) LIGH-T V4 Tethered Station (LTS4), including switches, a reel for the cable, and the battery connector. (b) Detail of the battery connector.