Railway Bridge Speed Measurement from Entry–Exit Timing
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Solution Overview
Problem
Existing railway vehicle speed measurement methods face challenges in accurately measuring speed when vehicles decelerate or accelerate, particularly when crossing bridges, due to increased costs and decreased accuracy from weak laser reflections, and difficulty in determining entry and exit times.
Innovation Solution
A measurement method and apparatus using an observation apparatus on a bridge to calculate the traveling speed function by acquiring observation data, calculating entry and exit times, and determining speed based on acceleration data and environmental information, including bridge length and vehicle dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a laser light source is mounted on each railway vehicle for speed measurement, then speed measurement capability is improved, but cost increases
Solution Approach 1:
Instead of mounting the laser light source on the moving railway vehicle, the patent inverts the arrangement by placing the laser light source and photodetector on the stationary bridge structure. The railway vehicle becomes the passive object being measured, eliminating the need for expensive equipment on each vehicle while maintaining measurement capability.
Solution Approach 2:
The patent introduces an intermediary measurement system on the bridge that uses laser beams to measure the speed of passing railway vehicles. This intermediary system acts as a mediator between the bridge infrastructure and the vehicles, enabling speed measurement without modifying the vehicles themselves.
2Measurement precision
If a laser light source is mounted on each railway vehicle for speed measurement, then speed measurement capability is improved, but measurement accuracy decreases when reflected light or scattered light is weak
Solution Approach 1:
By inverting the measurement system arrangement and placing the laser source and detector on the bridge rather than on the vehicle, the system achieves more stable measurement conditions. The stationary position allows for optimized laser beam angles and consistent detection geometry, improving reliability especially when reflected light is weak.
3Ease of manufacture
If a measuring instrument is provided at the bridge to measure passing time, then measurement cost is reduced, but it is not possible to easily measure speed when the railway vehicle enters or exits the bridge
Solution Approach 1:
The patent replaces traditional mechanical speed measurement instruments with an optical measurement system using laser beams and photodetectors. This optical system can accurately measure speed during entry and exit phases by detecting the timing of when vehicles interrupt the laser beams, overcoming the limitations of mechanical instruments while maintaining cost-effectiveness.
4Ease of manufacture
If a measuring instrument is provided at the bridge to measure passing time, then measurement cost is reduced, but measurement accuracy decreases for vehicles decelerating or accelerating
Solution Approach 1:
The optical laser-based measurement system replaces mechanical instruments, enabling accurate speed measurement during acceleration and deceleration phases. The system calculates instantaneous speed by measuring the time intervals when vehicles interrupt laser beams at different positions, providing accurate speed data even when vehicles are changing speed, unlike mechanical instruments that measure only average speed.
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
Accurately measures the traveling speed function of railway vehicles while decelerating or accelerating across bridges, improving measurement accuracy and reducing costs by eliminating the need for individual vehicle installations.
Implementation Method 1
observation data output from the observation apparatus, the observation data including a response to an action of the railway vehicle on the observation point
Data Source
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AI summary
A measurement method includes: an observation data acquisition step of acquiring observation data output from an observation apparatus; a passing time calculation step of calculating, based on the observation data, an entry time when a railway vehicle enters one end of a bridge and an exit time when the railway vehicle exits another end, and calculating a time which is a difference between the exit time and the entry time as a passing time; and a traveling speed function calculation step of calculating a traveling speed function when the railway vehicle travels on the bridge based on the passing time, a traveling distance of the railway vehicle during the passing time, a distance between a stop position of the railway vehicle and a position of an end of the bridge closer to the stop position, and a length between a front surface of a leading car and a leading axle of the railway vehicle.