Rail Vehicle Speed Detection via Magnetic Signature Comparison
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Solution Overview
Problem
Conventional methods for measuring the speed of rail vehicles are unreliable and imprecise, especially at low speeds, due to limitations in sensor technologies such as wheel slip, interference from environmental conditions, and inability to detect standstill.
Innovation Solution
A procedure that uses at least three magnetic field sensors to record local magnetic signatures along a rail route, allowing for the determination of the distance covered by the rail vehicle and its true ground speed by comparing these signatures over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional wheel path sensors are used to measure vehicle speed, then the measurement system is simple and inexpensive, but the measurement precision deteriorates due to wheel slip relative to the rail
Solution Approach 1:
The patent replaces mechanical wheel path sensors with magnetic field sensors that detect magnetic inhomogeneities in the track system. This substitution eliminates the dependency on wheel-rail contact and mechanical coupling, thereby resolving the wheel slip problem while maintaining measurement functionality.
Solution Approach 2:
The patent introduces magnetic field sensors as an intermediary measurement medium that detects the magnetic signature of the track system indirectly. Instead of measuring wheel rotation directly, the system uses magnetic field variations as a mediator to determine vehicle position and speed, avoiding the wheel slip issue entirely.
2Adaptability or versatility
If radar sensors are used for speed measurement, then the system can operate in various conditions, but the reliability deteriorates in snow, ice and dirt conditions
Solution Approach 1:
The patent replaces radar sensors with magnetic field sensors that detect magnetic inhomogeneities in the track system. Magnetic field detection is not affected by weather conditions such as snow, ice, or dirt, thereby maintaining reliability while preserving operational versatility.
3Device complexity
If optical path sensors are used for measurement, then the system structure is simple, but the measurement precision deteriorates due to impairment by dirt and dust
Solution Approach 1:
The patent replaces optical path sensors with magnetic field sensors. Magnetic field detection does not involve line-of-sight requirements and is not affected by dirt or dust accumulation on sensor surfaces, thereby maintaining simple system structure while eliminating precision degradation from environmental contamination.
4Duration of action of moving object
If inertial navigation systems are used for speed measurement, then the system can provide continuous measurement, but the measurement precision deteriorates due to sensitivity to shocks and vibrations
Solution Approach 1:
The patent replaces inertial navigation systems with magnetic field sensors that detect track magnetic signatures. This substitution eliminates the sensitivity to shocks and vibrations that plagues inertial systems, while maintaining continuous measurement capability through ongoing detection of magnetic field variations.
5Loss of information
If global satellite navigation signals are used for speed measurement, then the system can provide absolute position information, but the reliability deteriorates in tunnels and narrow mountain valleys
Solution Approach 1:
The patent uses magnetic field sensors as an intermediary that detects local magnetic signatures of the track system. This local magnetic field-based measurement provides continuous position and speed information independent of satellite signals, thereby maintaining reliability in tunnels and valleys where GPS is unavailable.
6Power
If magnetic odometry with two magnetometers is used for speed measurement, then the system can determine vehicle speed, but the measurement precision deteriorates at low speeds due to increased time delay
Solution Approach 1:
The patent segments the measurement function by using at least three magnetometers instead of two, with at least one magnetometer positioned laterally offset from the vehicle's direction of travel. This segmentation of measurement positions enables detection of magnetic signature changes even at low speeds, preventing time delay from degrading precision.
Solution Approach 2:
The patent extends the measurement from a single line (direction of travel) to multiple dimensions by positioning magnetometers both along the direction of travel and laterally offset. This dimensional expansion creates additional measurement baselines that remain effective at low speeds, overcoming the time delay limitation of linear arrangements.
7Power
If magnetic odometry with two magnetometers is used for speed measurement, then the system can determine vehicle speed, but the reliability deteriorates due to inability to detect standstill
Solution Approach 1:
The patent segments the measurement function by using at least three magnetometers with lateral offset positioning. This segmentation enables the system to detect magnetic signature changes even when the vehicle is stationary or moving very slowly, thereby providing reliable standstill detection that a two-magnetometer system cannot achieve.
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 precise and contemporary determination of the rail vehicle's speed and distance, even at low speeds, and allows for reliable standstill detection, improving safety and operational efficiency.
Implementation Method 1
recording values of a local magnetic flux density using at least three magnetic field sensors arranged at intervals on the rail vehicle in one direction of travel
Data Source
Figure 1A~1D
Figure 2A~2D
AI summary
In a method for detecting the movement of a rail vehicle (1) along a track (2), values of a local magnetic flux density are recorded within a first time interval by means of at least three magnetic field sensors (11.1...11.n) arranged at intervals on the rail vehicle in one direction of travel (1). From these values, a first local magnetic signature is determined, corresponding to a first spatially dependent profile of the local magnetic flux density. Within a second time interval, values of the local magnetic flux density are again recorded by means of the at least three magnetic field sensors (11.1...11.n) arranged on the rail vehicle (1). From these, a second local magnetic signature is determined, corresponding to a second spatially dependent profile of the local magnetic flux density.By comparing the first local magnetic signature with the second local magnetic signature, the distance traveled by the rail vehicle (1) along the track (2) is determined. This method allows for the precise and time-accurate determination of the distance traveled in a given time interval, even during slow movements of the rail vehicle (1).