Traffic Signal LED Flicker Detection for Flashing State Classification
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Solution Overview
Problem
Traffic signal element state classification is hindered by light emitting diode (LED) flickering, which can be misinterpreted as a flashing signal, posing challenges for autonomous vehicles (AVs) in accurately determining the state of traffic signals.
Innovation Solution
A method and system that capture a series of images of traffic signal elements over time, analyze the images to determine distinct on and off states, and identify cycles to classify the signal as flashing, using confidence scores and thresholds to differentiate between flickering and flashing LEDs, thereby sending appropriate instructions to the AV.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If standard object detection techniques are used to detect traffic signal elements, then the detection process is simple and fast, but LED flickering is misinterpreted as flashing signals reducing measurement precision
Solution Approach 1:
The patent segments the detection process into multiple analysis stages: capturing multiple images over time, analyzing intensity variations, determining on/off states with confidence scores, and identifying patterns. This segmentation allows the system to distinguish between flickering and flashing by breaking down the complex detection task into manageable temporal segments, thereby improving measurement precision without overwhelming system complexity.
Solution Approach 2:
The system performs preliminary actions by capturing a series of images before making a final determination. By pre-capturing multiple frames and performing preliminary intensity analysis, the system establishes a temporal pattern baseline that helps distinguish LED flickering from actual flashing signals, improving state determination accuracy before final classification.
2Measurement precision
If multiple images are captured and analyzed over time to distinguish flickering from flashing, then measurement precision improves, but loss of time increases
Solution Approach 1:
The system applies partial action by using confidence score thresholds to determine when sufficient analysis has been performed. Instead of analyzing every possible frame, the system stops when confidence scores indicate a clear distinction between flickering and flashing patterns, achieving acceptable precision without excessive time investment. The analysis continues only as long as needed to reach a confident determination.
Solution Approach 2:
The patent implements periodic action by analyzing images at regular time intervals rather than continuously. The system captures images periodically and analyzes intensity variations at these discrete time points, establishing patterns through periodic sampling. This approach maintains measurement precision by capturing sufficient temporal information while reducing overall processing time compared to continuous analysis.
3Measurement precision
If confidence scores and thresholds are used to differentiate flickering from flashing, then measurement precision improves, but device complexity increases
Solution Approach 1:
The system utilizes parameter changes by monitoring intensity values over time and comparing them against threshold parameters. Confidence scores are generated based on whether intensity measurements exceed or fall below predetermined thresholds, creating distinct on/off state classifications. This parameter-based approach improves measurement precision by providing quantitative criteria for differentiation while keeping the algorithm relatively simple through straightforward threshold comparisons.
Data Source
AI summary
Systems and methods are provided for detecting a flashing light on one or more traffic signal devices. The method includes capturing a series of images of one or more traffic signal elements in a traffic signal device over a length of time. The method further includes, for each traffic signal element, analyzing the series of images to determine one or more time periods at which the traffic signal element is in an on state or an off state, and analyzing the time periods to determine one or more distinct on states and one or more distinct off states. The method further includes identifying one or more cycles correlating to a distinct on state immediately followed by a distinct off state, or a distinct off state immediately followed by a distinct on state, and, upon identifying a threshold number adjacent cycles, classifying the traffic signal element as a flashing light.