Vehicle Presence Detector Using Magnetic Field Gradient
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Solution Overview
Problem
Current contactless vehicle presence detection systems using magnetic field sensors face limitations in stationary detection, sensitivity, and interference from environmental factors, leading to inaccurate and unreliable vehicle presence monitoring, especially in varying orientations and distances.
Innovation Solution
A vehicle presence detector employing a configuration of aligned and orthogonal vector sensors, with a vehicle presence evaluation block, calculates the magnetic field's homogeneous and gradient components, and a scalar value, to enhance detection accuracy and stability, reducing interference from environmental factors and allowing for increased detection distance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If induction coils are used for magnetic field sensing, then vehicle presence detection is achieved, but stationary detection capability is lost
Solution Approach 1:
The patent changes the sensing mechanism from induction-based to direct magnetic field vector sensing, enabling detection of both dynamic and stationary magnetic field variations. This parameter change in the detection method allows stationary vehicle detection while maintaining reliability.
Solution Approach 2:
The patent replaces the induction coil system with vector magnetic field sensors that directly measure magnetic field components. This substitution enables the system to detect both moving and stationary vehicles by measuring magnetic field vectors rather than relying on motion-induced currents.
2Adaptability or versatility
If vector sensors are used to detect direct and slowly variable magnetic field components, then stationary detection capability is achieved, but measurement precision deteriorates due to environmental interference
Solution Approach 1:
The patent divides the magnetic field measurement into two distinct components: homogeneous field (H) measured by one sensor and gradient field (G) measured by another sensor at a different location. This segmentation allows separate processing of interference-prone direct field and vehicle-specific gradient field, improving measurement precision.
Solution Approach 2:
The patent introduces a computational intermediary that processes the ratio H/G to extract vehicle presence information. This intermediary calculation method separates the vehicle signal from environmental interference by utilizing the different spatial characteristics of homogeneous and gradient field components.
3Reliability
If gradiometric arrangement of sensors is used to suppress interference, then reliability improves, but device complexity and dimensions increase
Solution Approach 1:
The patent segments the interference suppression function into two independent measurements: homogeneous field by one sensor and gradient field by another sensor. This segmentation simplifies the overall system architecture compared to complex gradiometric arrangements while achieving similar interference rejection.
Solution Approach 2:
The patent moves from a spatial gradiometric arrangement (requiring multiple sensors in specific geometric configurations) to a computational dimension where H and G are calculated from sensor outputs. This dimensional change reduces physical complexity while maintaining interference suppression effectiveness.
4Measurement precision
If sensors are placed under the vehicle for maximum sensitivity, then detection sensitivity improves, but ease of operation and installation are reduced
Solution Approach 1:
The patent inverts the traditional sensor placement approach by positioning sensors away from the vehicle (at a distance) rather than directly under it. This inversion, combined with gradient field measurement, maintains detection sensitivity while dramatically improving installation flexibility and ease of operation.
Solution Approach 2:
The patent uses the gradient field measurement as an intermediary that allows distance-based sensing. The gradient field decays with distance in a predictable manner, enabling sensitive detection from remote locations without requiring direct contact or proximity to the vehicle.
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
The solution provides a compact, sensitive, and selective vehicle presence detection system that is less sensitive to angular drifts and changes in the Earth's field, enabling reliable detection at greater distances and orientations, including overhead installations without construction, thus improving traffic management and parking space monitoring.
Implementation Method 1
the first vector sensor 1 and the second vector sensor 2, which lie on one line 12 and have a concurrent direction... measure the magnetic field
Implementation Method 2
magnetic field sensors use induction coils embedded, for example, in the road or floor
Data Source
Figure 1~2
AI summary
A vehicle presence detector, usable in particular for monitoring the occupancy of parking spaces or for the traffic control and regulation, comprises two magnetic field vector sensors (1,2) and the vehicle presence evaluation block (6) equipped with the software or hardware for evaluating the information from the vector sensors. Vector sensors (1,2) lie on a single line (12), they have parallel direction and their vertical distance ranges from 2 cm to 20 cm. Between their outputs and the input of the vehicle presence evaluation block (6) is inserted the block (5) of calculation of the vehicle distance from the detector. The output of the first vector sensor (1) is connected to the input of the first block (51) of converting the uncalibrated output values from the first vector sensor (1) to the calibrated values B1 proportional to the magnetic flux density, the output of which is connected both to the first input of the summing circuit (52), and to the first input of the differential circuit (55). The output of the second vector sensor (2) is connected to the input of the second block (54) of converting the uncalibrated output values from the second vector sensor (2) to the calibrated values B2 proportional to the magnetic flux density, the output of which is connected to both to the second input of the summing circuit (52), and to the second input of the differential circuit (55). The output of the summing circuit (52) is via the circuit (53) for dividing by two interconnected with the first input of the divider (57). The output of the differential circuit (55) is via the divider (56) for dividing by number d specifying the distance between the first vector sensor (1) and the second vector sensor (2) connected to the second input of the divider (57), the output of which is connected to the first input of the vehicle presence evaluation block (6). The output of this divider (57) and simultaneously the input of the vehicle presence evaluation block (6) is therefore the information L=H/G, where H was obtained as (B1+B2)/2 and G as (B1 -B2)/d. This information L is proportional to the distance of the detector from the vehicle (8), which is an advantageous classifier for processing in the vehicle (8) presence evaluation block (6).