Traffic Signal Recognition Using Link-Based Map Data
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Solution Overview
Problem
Existing traffic signal recognition systems face challenges in accurately specifying and recognizing traffic signals when multiple signals are present at an intersection, leading to incorrect targeting and recognition due to variations in vehicle direction, lanes, and camera views.
Innovation Solution
The system utilizes map information that includes traveling link data and traffic signal data, where each traffic lane is defined by a directed link with start and end points, and related traveling direction information, to correctly specify the targeted traffic signal, even in complex scenarios, using a camera with a moving mechanism and position detection device to adjust the image capture based on vehicle attitude and position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple traffic signals are captured in the image area, then the system can detect more signals, but the accuracy of specifying the correct targeted signal decreases
Solution Approach 1:
The patent divides the detection task into segments by associating each traffic signal with a specific traveling link (road segment). The control device specifies the targeted traffic signal by identifying which traveling link the own vehicle is currently on, then selecting only the traffic signal associated with that link, rather than attempting to identify the correct signal from all detected signals.
Solution Approach 2:
The patent introduces traveling link information as an intermediary data structure that connects the vehicle's position to the relevant traffic signal. This intermediary layer (traveling link data including start point, end point, and up/down direction) serves as a mediator that filters and identifies the correct traffic signal without requiring direct complex analysis of multiple signals.
2Area of stationary object
If the camera captures a wide area to ensure the targeted signal is included, then the probability of capturing the correct signal increases, but the likelihood of capturing irrelevant signals also increases
Solution Approach 1:
The system performs preliminary action by pre-establishing the relationship between traveling links and traffic signals in advance. The map information stores which traffic signals are associated with which traveling links before the vehicle arrives. When the vehicle is on a particular traveling link, the system can immediately identify the relevant traffic signal without needing to analyze the captured image content.
3Device complexity
If the system uses only image recognition to identify traffic signals, then the device complexity is reduced, but the reliability of specifying the correct signal in complex situations decreases
Solution Approach 1:
The patent merges two approaches: image recognition technology and map information-based traveling link data. The control device combines the captured image containing traffic signal candidates with pre-stored traveling link information to specify the targeted signal. This combination leverages the strengths of both methods while mitigating their individual weaknesses.
Data Source
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AI summary
A traffic signal recognition apparatus (100) including a control device (10) is provided. The control device (10) executes: a captured image acquisition function which acquires a captured image around an own vehicle from a camera (20); an own vehicle position acquisition function which acquires a current position of the own vehicle; a target traffic signal specifying function which refers to map information to specify a traffic signal to be targeted in a traveling link for the own vehicle, the map information including traveling link data and traffic signal data, the traveling link data including a connected link and traveling direction information which are related to each other, the connected link being defined by a directed link including a start point, an end point and an up direction or down direction and connected with each of the start point and the end point of the directed link, the traveling direction information specifying a traveling direction including straight ahead, right turn or left turn, the traffic signal data including position information about the traffic signal related to the traveling link; a traffic signal image area extraction function which extracts an image area of the traffic signal on the basis of the position information about the traffic signal and image capturing property information about the camera (20); and a traffic signal content recognition function which recognizes a traffic signal content of the traffic signal on the basis of an image of the traffic signal in the image area.