Ship Position Estimation Using Reliability-Adaptive Velocity Calculation
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Solution Overview
Problem
Inaccurate self-position estimation of ships due to tidal currents and waves, especially in urban coasts and rivers where GNSS reception is degraded, leading to reduced positioning accuracy.
Innovation Solution
An information processing device that calculates a ship's estimated position by updating a predicted position based on sensor data and map matching, with reliability calculation and velocity estimation using a time constant adjusted by reliability, to improve accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If scan matching is applied to improve self-position estimation accuracy, then positioning accuracy is improved, but errors caused by tidal currents and waves increase
Solution Approach 1:
The patent implements feedback by calculating reliability of matching results and using this reliability information to adjust the time constant in velocity calculation. The reliability calculation means assesses the quality of matching between sensor data and map data, and this reliability feedback is used to dynamically adjust the smoothing filter characteristics, thereby compensating for errors caused by tidal currents and waves.
Solution Approach 2:
The patent changes the parameter (time constant) of the velocity calculation based on the reliability of matching results. When reliability is high, a smaller time constant is used for more responsive velocity estimation, while when reliability is low, a larger time constant provides stronger smoothing to reduce errors from tidal currents and waves.
2Device complexity
If velocity calculation uses fixed time constant, then calculation simplicity is maintained, but accuracy under varying sea conditions deteriorates
Solution Approach 1:
The patent makes the time constant dynamic by adjusting it according to the reliability of matching results. Instead of using a fixed time constant, the system adapts the smoothing filter characteristics based on real-time assessment of data quality, allowing optimal performance under varying sea conditions while maintaining reasonable calculation complexity.
3Measurement precision
If reliability assessment is added to improve estimation accuracy, then positioning accuracy is improved, but system complexity increases
Solution Approach 1:
The reliability calculation means provides feedback on the quality of matching results, enabling the system to assess whether the current sensor data and map data alignment is reliable. This reliability information is then used to adjust the velocity calculation parameters, improving overall estimation accuracy without requiring complex additional hardware or algorithms.
Data Source
AI summary
An information processing device includes a predicted position acquisition means, an estimated position calculation means, a reliability calculation means, and a velocity calculation means. The predicted position acquisition means acquires a predicted position of a ship. The estimated position calculation means calculates an estimated position of the ship in which the predicted position is updated, based on a matching between data based on an output of an external sensor provided on the ship and map data. The reliability calculation means calculates a reliability of the matching. The velocity calculation means calculates a velocity of the ship at a first process time based on the estimated position at the first process time, an estimated position at a second process time immediately before the first process time, and a time constant set depending on at least the reliability.