Moving Object Position Estimation Using Structural Shape Features
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Solution Overview
Problem
Existing position estimation techniques, such as those using GPS signals or SLAM, are ineffective in environments like tunnels where constant changes in the surrounding environment are minimal, and installing light irradiation targets for train position detection is costly and impractical in all cases, especially in water conduits.
Innovation Solution
A position estimation device that acquires shape information of surrounding structures, extracts feature portions indicating shape changes, and compares this information with stored reference data to estimate the current position of a moving object, allowing for accurate positioning without the need for additional infrastructure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If light irradiation means and light receiving means are installed for train position detection, then position detection capability in tunnels is improved, but device complexity and installation cost increase
Solution Approach 1:
The train itself serves as the light source for position detection. The train's headlight irradiates the track ahead, and reflected light from track features is detected by the light receiving means mounted on the train. This eliminates the need for separate light irradiation infrastructure, allowing the train to perform its own position detection using its existing lighting capability.
Solution Approach 2:
Track features (such as ties, rails, or other permanent track structures) serve as intermediaries that reflect light from the train's headlight back to the light receiving means. These natural track features act as passive reflectors, enabling position detection without requiring active transponders or specialized reflective markers to be installed on the track.
2Measurement precision
If light irradiation targets are installed in tunnels for position detection, then position estimation accuracy is improved, but installation cost and practicality worsen
Solution Approach 1:
The train's existing headlight is utilized as the light source for position detection, eliminating the need to install separate light irradiation targets or transponders in the tunnel. The train performs position detection using its own lighting capability and the natural reflective properties of track features.
Solution Approach 2:
The system uses permanent, naturally occurring track features (ties, rails, ballast patterns) as reflection targets instead of requiring expensive, installable transponders or reflective markers. These track features already exist and require no additional installation cost, serving as free, permanent reference points for position estimation.
3Reliability
If SLAM technique is used for position estimation, then position grasping capability is improved, but reliability in tunnels worsens due to lack of environmental changes
Solution Approach 1:
The system replaces SLAM's complex mechanical/motion-based sensing approach with an optical sensing approach using light irradiation and reflection. Instead of relying on inertial sensors and detecting environmental changes over time, the system uses the train's headlight to illuminate track features and detects their reflected light patterns, providing stable position references that do not depend on motion or environmental changes.
Solution Approach 2:
The system pre-processes the reflected light signals to extract characteristic patterns from track features before comparing them with stored reference data. By analyzing the spatial and temporal patterns of reflected light from known track features, the system establishes position references in advance, enabling reliable position estimation without requiring continuous environmental changes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate and cost-effective position estimation of moving objects in environments where traditional methods fail, such as tunnels and water conduits, by utilizing feature extraction and comparison with stored reference data.
Implementation Method 1
the sensor irradiates a surface of an inner wall with a beam, acquires reflected light from the surface
Data Source
AI summary
Provided is a position estimation device capable of appropriately grasping a position of a moving object. According to the present disclosure, a position estimation device (10) includes an acquisition unit (11) configured to acquire shape information of a surface of a structure around a moving object, an extraction unit (12) configured to extract a feature portion indicating a shape change of the surface of the structure from the shape information and extract feature information including a position and a size of the feature portion, a storage unit (13) configured to store, in advance, reference information including a position and a size of a reference portion that is a reference for position estimation, and an estimation unit (14) configured to compare the feature information with the reference information and estimates a current position of the moving object.