Online Navigation Planning for Long-term Autonomous Operation of Underwater Gliders
This addresses the need for practical autonomous systems to manage fleets of underwater gliders for ocean sampling, representing a domain-specific incremental advance.
The paper tackled the problem of autonomous long-term navigation for underwater gliders by formulating it as a stochastic shortest-path Markov Decision Process and proposing a sample-based online planner using Monte Carlo Tree Search, validated in field deployments totaling 3 months and 1000 km, showing improved efficiency over straight-to-goal navigation.
Underwater glider robots have become an indispensable tool for ocean sampling. Although stakeholders are calling for tools to manage increasingly large fleets of gliders, successful autonomous long-term deployments have thus far been scarce, which hints at a lack of suitable methodologies and systems. In this work, we formulate glider navigation planning as a stochastic shortest-path Markov Decision Process and propose a sample-based online planner based on Monte Carlo Tree Search. Samples are generated by a physics-informed simulator that captures uncertain execution of controls and ocean current forecasts while remaining computationally tractable. The simulator parameters are fitted using historical glider data. We integrate these methods into an autonomous command-and-control system for Slocum gliders that enables closed-loop replanning at each surfacing. The resulting system was validated in two field deployments in the North Sea totalling approximately 3 months and 1000 km of autonomous operation. Results demonstrate improved efficiency compared to straight-to-goal navigation and show the practicality of sample-based planning for long-term marine autonomy.