REACT: Real-time Entanglement-Aware Coverage Path Planning for Tethered Underwater Vehicles

TL;DR

REACT is a real-time planning framework that ensures tethered underwater vehicles can safely inspect structures without tether entanglement by actively managing tether length and configuration.

Contribution

This paper introduces a novel geometry-based tether model and online replanning strategy for entanglement-aware coverage path planning in underwater inspections.

Findings

REACT achieves 20% faster mission completion than conventional planners.

REACT successfully prevents tether entanglement in simulations and real-world tests.

The framework enables safe, full-coverage inspection of underwater structures.

Abstract

Inspection of underwater structures with tethered underwater vehicles is often hindered by the risk of tether entanglement. We propose REACT (real-time entanglement-aware coverage path planning for tethered underwater vehicles), a framework designed to overcome this limitation. REACT comprises a computationally efficient geometry-based tether model using the signed distance field (SDF) map for accurate, real-time simulation of taut tether configurations around arbitrary structures in 3D. This model enables an efficient online replanning strategy by enforcing a maximum tether length constraint, thereby actively preventing entanglement. By integrating REACT into a coverage path planning framework, we achieve safe and entanglement-free inspection paths, previously challenging due to tether constraints. The complete REACT framework's efficacy is validated in a pipe inspection scenario, demonstrating safe navigation and full coverage inspection. Simulation results show that REACT achieves complete coverage while maintaining tether constraints and completing the total mission 20% faster than conventional planners, despite a longer inspection time due to proactive avoidance of entanglement that eliminates extensive post-mission disentanglement. Real-world experiments confirm these benefits, where REACT completes the full mission, while the baseline planner fails due to physical tether entanglement.