Speed Detection via License Plate Character Dimension Analysis
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Solution Overview
Problem
Existing systems for detecting speeding violations are unreliable due to variations in license plate dimensions and environmental factors such as background colors and obstructions, which can lead to inaccurate distance and speed measurements.
Innovation Solution
A computerized system using a camera connected to a processor that captures timed image frames, recognizes alphanumeric characters on a license plate, measures their dimensions, and computes the speed of a target vehicle by correlating image dimensions with known standard plate dimensions, while also utilizing sensors like GPS and LIDAR for accurate ego-motion analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If license plate dimension comparison is used to determine vehicle speed, then speed measurement can be obtained, but measurement precision deteriorates due to variations in license plate dimensions and environmental factors
Solution Approach 1:
The system changes the measurement parameter from license plate dimension to alphanumeric character dimension. By measuring the dimensions of recognized characters (which have standardized fonts and sizes) and comparing them to known values, the system calculates vehicle distance and speed with higher precision, overcoming the variability issues of license plate dimensions
Solution Approach 2:
The system introduces character recognition as an intermediary step between image capture and speed measurement. By first recognizing alphanumeric characters and their dimensions, then using these measurements to calculate speed, the system creates a more reliable measurement chain that accounts for environmental factors and plate variations
2Measurement precision
If multiple sensors (GPS, LIDAR, accelerometers) are integrated for ego-motion analysis, then measurement precision improves, but device complexity increases
Solution Approach 1:
The system makes the camera multi-functional by using it for both target vehicle license plate recognition and ego-motion analysis through optical flow. This reduces device complexity by eliminating dedicated sensors while maintaining measurement precision through the dual-use of the camera system
Solution Approach 2:
The system uses its own camera footage to determine ego-motion through optical flow analysis, rather than relying on separate GPS or accelerometer sensors. The camera serves itself to provide both target identification and self-motion reference, reducing overall system complexity while maintaining precision
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 system provides high-accuracy distance and speed measurements, essential for enforcing speeding regulations, by mitigating the unreliability issues of previous methods through character recognition and sensor integration, ensuring measurements are precise to a few percent.
Implementation Method 1
capture a timed sequence of image frames of the target vehicle
Implementation Method 2
Ego-motion of the host vehicle may be determined by optical flow in the image frames
Implementation Method 3
a LIDAR and/or a gyroscope
Data Source
AI summary
Determining that a vehicle is speeding in violation of a speeding regulation. Capture a timed sequence of image frames of the target vehicle at known capture times of the vehicle, identify corresponding images of a license plate of the target vehicle in the image frames, recognize an alphanumeric character of the license plate in the corresponding images of the license plate, measure respective image dimensions of the alphanumeric character; and responsive to a change between the image dimensions of the alphanumeric character, compute a speed of the target vehicle relative to the camera. Font style and font size are stored of one or more standard vehicle license plate.