Train Position Detection Using GNSS and Self-Contained Navigation
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Solution Overview
Problem
GNSS-based train position sensing systems face accuracy issues due to obstacles like vehicle roofs, which obstruct satellite signals, leading to degraded radio wave reception and positioning accuracy, especially in environments like train stations.
Innovation Solution
A train position detection apparatus that combines GNSS signals with self-contained navigation data, using a reception antenna installed near the cab to filter direct waves and correct position calculations based on railway design standards, ensuring accurate positioning by excluding unsuitable satellites and integrating self-contained navigation data when GNSS data deviates from standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the GNSS reception antenna is installed on the roof of the vehicle, then the satellite signal reception is improved, but the vehicle cannot pass authentication because the antenna was not mounted during vehicle authentication
Solution Approach 1:
The patent introduces a signal processing intermediary system that separates the antenna installation location from the signal processing location. The GNSS reception antenna is installed on the roof to capture satellite signals, while the signal processing is performed by the train position detection apparatus inside the vehicle. This intermediary arrangement allows the system to benefit from roof-mounted antenna signal reception while maintaining authentication compliance by processing signals through approved onboard equipment.
2Reliability
If the GNSS reception antenna is installed indoors, then the vehicle passes authentication, but the positioning accuracy decreases due to roof obstacles blocking satellite signals
Solution Approach 1:
The patent addresses the spatial constraint by utilizing the vertical dimension. The GNSS reception antenna is positioned on the roof surface, which is the highest point of the vehicle, allowing it to receive satellite signals from above while the indoor installation requirement is satisfied for the processing equipment. This dimensional separation allows both authentication compliance and signal reception quality to be maintained.
3Reliability
If satellites are tracked through the roof, then the vehicle passes authentication, but the reception state of radio waves degrades due to reflected waves and insufficient satellite visibility
Solution Approach 1:
The patent changes the installation parameter of the GNSS reception antenna from indoor to roof-mounted position. This parameter change fundamentally alters the signal reception characteristics by providing direct line-of-sight to satellites, eliminating the need to track satellites through the roof structure. The parameter change from installation location to signal source location resolves the contradiction between authentication compliance and signal quality.
Data Source
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AI summary
A railway design standard storage unit in a train position detection apparatus according to an embodiment stores in advance a railway design standard of a railway track on which a train travels. A position detection unit detects a position of the train by receiving positioning radio waves from satellites through a reception antenna, and simultaneously detects a position of the train by self-contained navigation based on an input signal from a self-contained navigation sensor. When a result of the train position detection based on the positioning radio waves does not satisfy the railway design standard, the position detection unit corrects the result of the train position detection based on the positioning radio waves with a result of the position detection by self-contained navigation. Accordingly, even a vehicle of a train provided with a position detection system after authentication of the vehicle can suppress degradation of positioning accuracy at a place where the direct waves of the positioning radio waves from the satellites cannot be received.