Autonomous Vessel Path Planning Under Drift Constraints
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Solution Overview
Problem
Current autonomous marine vessel path planning systems fail to effectively account for drift conditions, leading to inaccuracies and inefficiencies in navigation, particularly for vessels with tows, as they do not adequately adjust for ocean currents and tidal influences during the planning phase.
Innovation Solution
A method and system that determine a modified primary path by extrapolating points along the planned path under drift conditions, assessing whether motion constraints are breached, and revising the path to ensure navigability, using techniques such as Dubin's curves and rapidly exploring random trees, while incorporating data from on-board sensors to account for ocean drift and vessel capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a primary path is planned without accounting for drift conditions, then the path planning is simpler and faster, but the navigation accuracy deteriorates and the vessel deviates from the intended path
Solution Approach 1:
The patent applies preliminary action by calculating drift extrapolated positions before path validation. The system determines where path points will drift to under current conditions, then validates the modified path against motion constraints before execution. This advance preparation ensures navigation accuracy without adding complex real-time adjustments during path following.
Solution Approach 2:
The patent segments the path planning process into distinct stages: primary path generation, drift extrapolation, modification, and validation. By dividing the complex task of drift-compensated path planning into manageable segments, the system maintains computational efficiency while improving navigation accuracy through systematic drift compensation.
2Measurement precision
If the path is revised to account for drift conditions, then the navigation accuracy improves, but the computation time increases
Solution Approach 1:
The patent applies partial action by calculating drift extrapolation only for the specific path points that need validation, rather than recalculating the entire path. The system determines drift for individual points along the primary path and only modifies points where drift causes constraint violations, reducing unnecessary computation while maintaining accuracy.
Solution Approach 2:
The system uses the vessel's own motion constraints and drift conditions to self-validate the modified path. By checking whether drift-extrapolated positions violate motion constraints using the vessel's inherent operational limits, the system avoids requiring external validation systems, thereby reducing computational overhead while ensuring path feasibility.
3Reliability
If the turn radius is increased to accommodate drift conditions, then the path remains within motion constraints, but the path length increases
Solution Approach 1:
The patent applies parameter changes by adjusting the turn radius parameter specifically at points where drift extrapolation indicates constraint violations. Rather than uniformly increasing the turn radius for the entire path, the system modifies only the local geometry where needed, thereby maintaining constraint compliance while minimizing the overall path length increase.
4Use of energy by moving object
If drift conditions are accounted for during path planning, then energy efficiency improves, but the device complexity increases
Solution Approach 1:
The patent applies feedback by using drift conditions and motion constraint violations as input to iteratively modify the path. The system calculates drift extrapolated positions, checks for constraint violations, and adjusts the path accordingly, creating a feedback loop that optimizes energy efficiency by ensuring the vessel follows a drift-compensated path without requiring complex predictive models of future drift conditions.
Data Source
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AI summary
Disclosed is a path planning method for an autonomous marine vessel, comprising: obtaining a primary path of travel for the vessel; obtaining drift conditions for the vessel travelling along the primary path; determining a modified primary path which represents the primary path adjusted with the drift conditions; determining whether the modified primary path is navigable within predetermined motion constraints of the vessel; and, providing the primary path as the path for the vessel if the modified primary path is navigable within the predetermined motion constraints of the vessel.