Vehicle Speed Determination Using Magnetometer Array Correlation
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Solution Overview
Problem
Existing methods for contactless speed determination of rail-guided vehicles face issues such as sliding and slipping effects, complexity, high costs, interference, and reliability problems due to environmental and mechanical vulnerabilities, especially in non-standardized substructures and adverse weather conditions.
Innovation Solution
The use of networked magnetometers installed on the vehicle to measure and compare the magnetic profiles of the subsurface in real-time, allowing for accurate speed calculation through time differences and phase shifts, with the option to combine with acceleration sensors for redundancy and improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If wheel rotation detection is used for speed measurement, then the system is simple and low-cost, but it is susceptible to sliding and slipping effects which reduce measurement accuracy
Solution Approach 1:
The patent replaces the mechanical wheel rotation detection system with an electromagnetic field-based measurement system. Magnetic sensors detect changes in the magnetic field caused by the vehicle's movement through the Earth's magnetic field, eliminating the need for physical contact with the wheels and thus avoiding sliding and slipping errors while maintaining system simplicity.
Solution Approach 2:
The patent introduces the Earth's magnetic field as an intermediary medium for speed measurement. Instead of directly measuring wheel rotation, the system uses magnetic sensors to detect variations in the magnetic field that occur as the vehicle moves, providing an indirect but accurate measurement of speed that is not affected by wheel-surface interactions.
2Measurement precision
If radar measurements based on the Doppler effect are used, then sliding and slipping effects are avoided, but the system becomes complex and expensive with high risk of failure
Solution Approach 1:
The patent substitutes the complex radar system with a simpler magnetic field detection system. Instead of using radio waves and Doppler effect calculations requiring sophisticated transmission and reception technology, the system uses magnetic sensors to directly detect magnetic field variations, achieving similar accuracy with much reduced complexity and cost.
Solution Approach 2:
The patent changes the measurement parameter from radio frequency signals (radar) to magnetic field parameters. By measuring changes in magnetic field strength and direction rather than using Doppler-shifted radio waves, the system achieves accurate speed measurement without requiring complex signal processing hardware and software.
3Measurement precision
If satellite navigation systems are used for speed determination, then highly accurate position and speed information is provided, but the system is vulnerable to interference and signal disruption
Solution Approach 1:
The patent uses the Earth's magnetic field as a local, always-present intermediary for measurement that does not require external satellite signals. This local field is unaffected by jamming or interference that can disrupt satellite communications, providing reliable speed measurement in environments where GPS signals may be blocked or corrupted.
Solution Approach 2:
The system uses the Earth's magnetic field, which is naturally present and requires no external infrastructure or active transmission. The vehicle carries its own magnetic sensors that continuously measure the magnetic field, making the system self-sufficient and independent of external satellite systems that can be disrupted or jammed.
4Measurement precision
If optical speed measurement systems are used, then non-contact measurement is achieved, but the systems are vulnerable to weather conditions, contamination, and require sufficient illumination
Solution Approach 1:
The patent replaces optical measurement systems with magnetic field-based sensors. Instead of using light that can be blocked by weather, contamination, or lack of illumination, the system uses magnetic sensors that detect changes in the magnetic field, which are not affected by optical conditions and can operate reliably in all weather and lighting conditions.
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
This solution provides reliable and accurate speed measurement independent of surface conditions, reduces complexity and cost, and enhances robustness against interference and environmental factors, making it suitable for both rail-guided and free-moving vehicles, including those in cross-border operations.
Implementation Method 1
The magnetic field of the ground is measured independently at or from several locations on the vehicle
Implementation Method 2
Time-resolved measurement makes it possible to determine at which time the stationary magnetic profile of the ground was detected by which sensor. Together with the known geometry (or spacing) of the sensors on the vehicle, the speed can be calculated from the time difference (phase shift)
Data Source
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AI summary
To make a device for the contactless determination of a vehicle's speed more reliable, it is proposed that the device comprise at least two magnetometers spaced apart from each other and be designed to determine the speed based on a comparison of the magnetic profiles of the at least two magnetometers. The detected signals are time-shifted relative to each other; the corresponding time difference can be determined by correlation. Given a known distance between the two magnetometers, the speed can be determined from this distance and the time difference.