Rail Wheel Direction Detection via Asymmetric Magnetic Field
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Solution Overview
Problem
Current systems for detecting train wheels on rail tracks lack the ability to determine the direction of motion effectively, especially in environments without electrified safety systems, and struggle with detecting symmetrical objects like train wheels in uniform magnetic fields.
Innovation Solution
A device comprising at least one magnet and a magnetic field sensor, configured to analyze changes in magnetic field values over time to determine the direction of motion of a wheel, using a processor to compare flux density readings and detect significant changes indicative of a wheel's presence and direction, even in the presence of symmetrical objects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single Hall effect device is used to detect wheel passage, then the detection of wheel presence is achieved, but the direction of motion cannot be determined
Solution Approach 1:
The single detection function is segmented into multiple sensors arranged in a specific geometry (e.g., three sensors in a triangular pattern). Each sensor detects magnetic field changes independently, and the combined signals from multiple sensors enable direction determination through signal comparison and analysis.
Solution Approach 2:
A permanent magnet is introduced as an intermediary element that generates a magnetic field which interacts with the conducting wheel. The wheel's motion through this magnetic field induces voltage changes in the sensors, providing the basis for detecting both presence and direction of motion.
2Measurement precision
If multiple sensors are used to determine direction and speed, then motion direction detection is improved, but device complexity increases
Solution Approach 1:
The magnetic field is configured to have specific local characteristics in different spatial zones around the sensor array. By positioning sensors at specific locations where the magnetic field has distinct properties, the system can determine direction from the pattern of field changes detected at each location.
Solution Approach 2:
The sensor array is positioned asymmetrically relative to the magnet and track, or the magnets are positioned asymmetrically, creating an uneven magnetic field distribution. This asymmetry ensures that the magnetic field changes detected by different sensors are distinct for forward versus backward wheel motion, enabling direction detection.
3Ease of manufacture
If a uniform magnetic field is used for detection, then the magnetic field setup is simple, but direction of motion of symmetrical objects cannot be detected
Solution Approach 1:
Instead of using a uniform magnetic field, the system employs an asymmetric magnetic field configuration through strategic placement of permanent magnets relative to the sensor array and rail track. This creates distinct magnetic field gradients in different directions, allowing the symmetric wheel to produce asymmetric voltage signals that reveal its direction of motion.
Solution Approach 2:
The magnetic field is configured to have significant spatial variation in multiple dimensions rather than being uniform. By creating magnetic field gradients in both magnitude and direction across the sensor array positions, the system can detect direction from the multidimensional pattern of field changes as the wheel passes.
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 detection of the direction of motion of train wheels, allowing for better tracking of vehicles and improved safety in marshalling yards, with the potential for extended battery life due to reduced power consumption and the ability to operate wirelessly for long periods.
Implementation Method 1
at least one magnet for providing a magnetic field
Implementation Method 2
sensing a magnetic field value indicative for a flux density, or a change in the flux density
Implementation Method 3
the wheel acts as a magnetic shunt, or magnetic field blocking or altering element. In other words, the magnetic field lines generated by the at least one magnet are short circuited
Data Source
AI summary
Disclosed are a method and device for detecting a direction of motion of a wheel on a rail track. The device includes at least one magnet for providing a magnetic field; a magnetic field sensor for sensing a magnetic field value indicative for a flux density, or a change in the flux density of the provided magnetic field; and at least one processor in communication with the magnetic field sensor. The at least one processor is configured to: obtain a plurality of the magnetic field values for respective times from the magnetic field sensor; and to analyse the obtained plurality of magnetic field values such that a direction of motion of a wheel passing the device is obtained.