Underwater Vehicle Position Detection via Map Matching
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Solution Overview
Problem
The existing nuclear reactor inspection systems face inaccuracies in detecting the position of underwater vehicles due to errors in displacement calculation, which accumulate and are not corrected until contact with internal structures is made, leading to reduced accuracy.
Innovation Solution
A position detection system for underwater vehicles that includes vertical position detecting means, relative distance detecting means, measurement image acquiring means, image storing means, image selecting means, corresponding-area identifying means, and horizontal position calculating means, utilizing correlation-based map matching to enhance accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If displacement values are calculated and integrated to determine absolute position, then the system can track the underwater vehicle's movement, but errors in displacement calculation accumulate and reduce position accuracy
Solution Approach 1:
The system continuously compares the measured position (from integration) with the expected position (from map matching) and uses this feedback to correct accumulated errors. The map matching process provides periodic absolute position references that reset the error accumulation, while the integration provides continuous relative position updates between these references.
Solution Approach 2:
The system pre-stores map data of the inspection space before the underwater vehicle enters. This preliminary preparation enables the vehicle to perform map matching against known structures during operation, providing absolute position references without requiring real-time external positioning systems.
2Measurement precision
If the system waits for contact with internal structures to correct position errors, then correction can be made, but accuracy is reduced during the period before contact
Solution Approach 1:
The system performs continuous map matching against pre-stored structural data throughout the inspection process, rather than waiting for contact events. This continuous operation maintains position accuracy at all times by constantly comparing sensor data with the stored map, eliminating periods where accuracy deteriorates without correction.
3Productivity
If integration of displacement values is used for position calculation, then continuous position tracking is achieved, but error accumulation occurs over time
Solution Approach 1:
The system uses map matching results as feedback to periodically correct the integrated position. The correction amount is calculated as the difference between the integrated position and the map-matched position, and this correction is applied to eliminate accumulated errors while maintaining continuous tracking capability.
Solution Approach 2:
By pre-storing accurate map data of the inspection environment, the system establishes a reference framework that enables continuous error correction during operation. This preliminary preparation allows the system to maintain both continuous tracking and high accuracy without requiring external positioning infrastructure.
Data Source
AI summary
The position detection system includes a pressure sensor that detects the vertical position of an underwater vehicle, a range sensor unit that detects the relative distances of the underwater vehicle from its surrounding structures; a measurement image acquisition unit that acquires a measurement image of the horizontal plane, an image storage unit that stores images, an image selector that selects one of the stored images that corresponds to the horizontal plane in which the relative distances have been detected, a corresponding-area identification unit that identifies the area in the selected image that corresponds to the measurement image by performing map matching, and a horizontal position calculator that identifies, the pixel that corresponds to the position at which the relative distances have been detected and calculates the horizontal position of the underwater vehicle.