Event-Based Sensor Flicker Filtering via Polarity Analysis
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Solution Overview
Problem
Event-based sensors generate excessive unwanted events when exposed to flickering light, overwhelming subsequent processing and preventing real-time applications due to misinterpretation of flickering light as motion.
Innovation Solution
An event-based sensor system comprising a photoarray and processing circuit that filters out events caused by flickering light by determining the polarity of light intensity changes and calculating a flicker probability based on time differences between events, discarding events above a threshold probability to retain only motion-related events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the event-based sensor outputs all pixel-level brightness changes, then the sensor captures all motion information, but the computational load becomes excessively high due to flicker-related events
Solution Approach 1:
The patent extracts and removes flicker-related events from the event stream by analyzing temporal patterns and polarity sequences. The system identifies events caused by flickering light and selectively filters them out, retaining only motion-related events for processing. This extraction approach maintains motion detection accuracy while reducing computational load.
Solution Approach 2:
The patent performs preliminary analysis of event polarity and temporal patterns before full processing. By evaluating the sequence of ON and OFF signals and calculating time differences between events, the system pre-identifies flicker-related events and marks them for filtering. This preliminary action prevents unnecessary processing of flicker events downstream.
2Reliability
If the sensor processes all events including flicker-induced events, then no motion information is lost, but real-time processing becomes infeasible due to overwhelming data volume
Solution Approach 1:
The patent extracts flicker-related events from the complete event stream through temporal pattern analysis. By identifying characteristic patterns of flicker (repetitive polarity changes at regular intervals), the system removes these events while preserving all genuine motion events. This ensures motion detection completeness is maintained without the time penalty of processing flicker artifacts.
Solution Approach 2:
The patent changes the processing approach by introducing temporal parameter analysis (time differences between events) and polarity sequence analysis. Instead of processing all events uniformly, the system uses these additional parameters to distinguish flicker events from motion events, enabling real-time processing by filtering out the overwhelming majority of flicker-induced events.
3Adaptability or versatility
If the sensor operates under flickering light conditions, then the sensor remains functional, but the output contains excessive unwanted events that overwhelm processing
Solution Approach 1:
The patent converts the harmful effect of flicker into a useful signal by exploiting the characteristic temporal patterns of flicker events. The systematic polarity changes and regular time intervals of flicker-induced events are identified and used as fingerprints for filtering. This approach maintains operational capability under flicker conditions while eliminating the harmful overflow of unwanted events.
Solution Approach 2:
The patent introduces an intermediary filtering stage between event generation and motion processing. This intermediary analyzes temporal patterns and polarity sequences to mediate between the raw event stream and the motion detection algorithm, blocking flicker-induced events while allowing genuine motion events to pass through. This maintains versatility under flicker conditions while eliminating harmful event overflow.
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
This approach significantly reduces computational load by eliminating flicker-related events, allowing for more efficient and accurate detection of moving objects, enhancing the sensor's performance in real-time applications.
Implementation Method 1
Each cell includes a photosensor generating a sensor signal dependent on intensity of light casted on the cell
Data Source
AI summary
An event-based sensor includes a photoarray and a processing circuit. The photoarray includes an array of cells. Each cell includes a photosensor generating a sensor signal dependent on an intensity of light casted on the cell, and an intensity monitoring circuit outputting an ON signal when the light intensity is increasing and an OFF signal when the light intensity is decreasing. The processing circuit is configured to generate an event in response to the ON and OFF signals, filter out the events caused by flickering light, and pass the events caused by motion.