Electromagnetic Induction Sensor Vehicle Detection Trajectory Analysis
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Solution Overview
Problem
Existing vehicle detection systems face challenges in accuracy due to environmental factors like electromagnetic noise, traffic congestion, and varying vehicle speeds, particularly in magnetic sensor systems and loop coil methods, which restrict their practical use and require additional equipment like wireless devices or GPS for vehicle identification.
Innovation Solution
A detection system utilizing an electromagnetic induction sensor with a transmission coil and differentially connected first and second reception coils, generating a trajectory image from detection waveforms in a coordinate system of reception level and phase difference to identify vehicles without the need for additional equipment on the vehicle, and determining vehicle type by comparing pre-registered reference images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If magnetic sensor system is used to detect vehicles, then vehicle detection is possible, but the system cannot be used in environments with electromagnetic noise such as along railways
Solution Approach 1:
The patent replaces the magnetic sensor system with an electromagnetic induction sensor system that uses coil-based detection. This substitution allows the system to detect vehicles through electromagnetic induction rather than magnetic field sensing, thereby eliminating the vulnerability to electromagnetic noise from railways while maintaining vehicle detection capability.
Solution Approach 2:
The patent changes the detection parameter from magnetic field strength (which is sensitive to electromagnetic noise) to inductance change of the loop coil (which is not affected by external electromagnetic noise). This parameter change enables the system to operate reliably in environments with electromagnetic noise such as along railways and around railroad crossings.
2Measurement precision
If loop coil method is used to detect vehicles, then vehicle type detection is possible, but the detection resolution depends on the large size of the loop coil
Solution Approach 1:
The patent divides the single large loop coil into multiple smaller coil units arranged in an array. Each coil unit can independently detect vehicles, and the segmented structure maintains detection precision while reducing the area of individual coils. The system achieves overall detection capability through the combined output of multiple segmented coil units.
Solution Approach 2:
The patent transitions from a single large two-dimensional loop coil to a multi-dimensional array of smaller coil units. By arranging coils in multiple rows and columns, the system achieves the detection resolution of a large coil while using smaller individual coil elements, effectively adding spatial dimensionality to the detection structure.
3Reliability
If magnetic sensor system is used, then vehicle detection is possible, but the output value becomes large when multiple vehicles are stopped in a row due to traffic congestion
Solution Approach 1:
The patent replaces the magnetic sensor system with an electromagnetic induction sensor system that detects vehicles through inductance changes. This substitution fundamentally changes the detection mechanism, allowing the system to distinguish individual vehicles even when multiple vehicles are stopped in a row, as each vehicle causes a distinct inductance change event that can be separately detected and counted.
4Reliability
If magnetic sensor system is used, then vehicle detection is possible, but the output changes depending on the passing speed of the vehicle
Solution Approach 1:
The patent changes the detection parameter from magnetic field strength (which varies with vehicle speed) to inductance change of the loop coil (which is independent of vehicle speed). The inductance change occurs regardless of how fast or slow the vehicle passes, eliminating the speed dependency problem and providing consistent detection output across varying vehicle speeds.
5Measurement precision
If additional equipment like wireless devices or GPS is installed in vehicles for specific vehicle extraction, then specific vehicle detection is possible, but the device complexity increases
Solution Approach 1:
The patent extracts the detection function from the vehicle-mounted equipment and places it entirely in the ground-based sensor system. By using electromagnetic induction sensors and trajectory image analysis, the system can identify specific vehicle types without requiring any additional equipment on the vehicles themselves, thereby eliminating the complexity of vehicle-mounted devices while maintaining specific vehicle detection capability.
Solution Approach 2:
The patent creates a trajectory image copy of the vehicle's detection waveform pattern and compares it with registered reference patterns to identify specific vehicle types. This copying and comparison approach enables specific vehicle detection using only ground-based equipment, eliminating the need for vehicle-mounted identification devices while achieving accurate vehicle type classification.
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 and classification of vehicles without the need for wireless devices or GPS, maintaining stability across varying environmental conditions and vehicle speeds, and effectively differentiates vehicle types based on unique trajectory patterns.
Implementation Method 1
a transmission coil and a first reception coil and a second reception coil that are differentially connected to each other
Implementation Method 2
an electromagnetic induction sensor including a transmission coil and a first reception coil and a second reception coil that are differentially connected to each other
Data Source
AI summary
Provided is a technique for detecting a vehicle type and a traveling direction of a vehicle by an electromagnetic induction sensor.A sensor unit (10), which is an electromagnetic induction sensor, includes a transmission coil (TX1), a first reception coil (RX1), and a second reception coil (RX2). A magnetic field of a vehicle (90) made of steel attracts a magnetic field emitted from the transmission coil (TX1) (S1). As the vehicle (90) approaches, a state 1 indicated by the broken line changes to a state 2 indicated by the dash-dot line (S2). A reduction in induced voltage and a phase change occur with respect to the induced voltage when the first reception coil (RX1) is in the magnetic field of state 1 (when the vehicle is not detected) (S3). The differential output signals of the second reception coil RX2 and the first reception coil RX1 change according to the advancement of the vehicle and according to the unevenness of the vehicle bottom portion 92 and the metal species (S4). The trajectory image representing a differential output signal in rectangular coordinates of a reception level and a phase difference is different for each vehicle, so the vehicle type may be distinguished.