Camera-Based License Plate Recognition for Vehicle Distance Measurement
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Solution Overview
Problem
Advanced driver assistance systems (ADAS) for autonomous driving, such as Adaptive Cruise Control (ACC), face challenges in accurately determining the position of a front vehicle without increasing costs, particularly when using lasers for distance measurement.
Innovation Solution
A vehicle system that uses a camera to acquire front images, recognizes license plates by matching them with stored reference images, and determines the position of the front vehicle based on the license plate's size, shape, aspect ratio, and movement, allowing for accurate distance calculation and vehicle positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If laser is used for accurate distance measurement, then measurement precision is improved, but device cost increases
Solution Approach 1:
The patent uses a camera to capture images of the front vehicle and extracts license plate information as a copy or proxy for direct distance measurement. Instead of using expensive laser ranging equipment, the system creates a visual copy of the target vehicle through imaging and processes this visual data to determine distance, thereby achieving accurate measurement without high-cost hardware
Solution Approach 2:
The patent replaces the mechanical/optical laser measurement system with an electronic image processing system. The camera-based visual recognition system substitutes for the laser-based physical measurement system, using software algorithms to analyze license plate size and position in images rather than direct optical time-of-flight measurement, thus reducing hardware costs while maintaining measurement capability
2Device complexity
If license plate recognition is used instead of laser, then device cost is reduced, but measurement precision may deteriorate
Solution Approach 1:
The system continuously captures images of the front vehicle and compares the license plate position and size across multiple frames. By tracking the movement and size changes of the license plate in sequential images, the system refines its distance estimation through feedback from ongoing observation, improving measurement precision over time despite using lower-cost camera equipment
Solution Approach 2:
The patent analyzes multiple parameters of the license plate including its pixel dimensions, aspect ratio, position in the image frame, and movement trajectory. By changing from a single measurement parameter to multiple parameters and analyzing their relationships, the system compensates for the lower inherent precision of camera-based measurement compared to laser, achieving acceptable distance accuracy through multi-parameter analysis
3Reliability
If outline image matching is used for license plate recognition, then recognition reliability is improved, but device complexity increases
Solution Approach 1:
The patent divides the license plate recognition task into distinct segments: first extracting the outline or contour of the detected plate region, then comparing this outline against stored reference outlines, and finally confirming recognition based on match quality. This segmentation of the recognition process into modular steps improves reliability through systematic verification while keeping each individual processing step relatively simple
Data Source
AI summary
A vehicle and a control method thereof are provided. The vehicle may include a camera configured to acquire a front image of the vehicle; a storage configured to store an outline image of a reference license plate, and store location information including a position of a front vehicle based on a size of the outline image of the reference license plate, and a controller configured to recognize a license plate included in the front image, and determine a position of the front vehicle based on the license plate and the location information.