Monochrome Sensor Green Filter Driver State Detection
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Solution Overview
Problem
Existing methods for monitoring a vehicle driver's condition using plethysmographic variables are limited by the need for continuous contact, complex and costly processing, and adverse visual impacts, particularly when using color cameras for ambient light photoplethysmography.
Innovation Solution
A method employing a monochrome image sensor with a structured green filter or an image sensor with green and transparent pixels, which records the driver's head and determines plethysmographic signals using a mathematical algorithm, allowing for robust and cost-effective detection without the need for continuous contact or additional illumination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a color camera is used for ambient light photoplethysmography, then the detection can be performed without additional illumination, but the processing complexity and costs increase significantly
Solution Approach 1:
The patent extracts only the green color component from the ambient light spectrum using a green bandpass filter, discarding other color information. This extraction approach simplifies the processing requirements while maintaining the ability to detect photoplethysmographic signals without additional illumination sources.
Solution Approach 2:
The patent changes the spectral parameter by using a green bandpass filter with specific wavelength range (480-560nm) to isolate the green component. This parameter change in the optical domain simplifies subsequent processing compared to full-color analysis, reducing computational complexity while enabling illumination-free operation.
2Measurement precision
If a monochrome image sensor with structured green filter is used, then the resolution and cost are optimized, but the implementation complexity increases
Solution Approach 1:
The patent segments the image sensor into different functional regions: a first region with a green bandpass filter for photoplethysmographic signal detection and a second region without filter for facial feature detection. This segmentation allows each region to be optimized for its specific function while using a single monochrome sensor, maintaining high resolution without requiring multiple specialized sensors.
Solution Approach 2:
The monochrome image sensor serves multiple functions: detecting photoplethysmographic signals in the first region and detecting facial features in the second region. This multi-functionality approach consolidates what would otherwise require separate sensors, reducing overall system complexity while maintaining detection precision.
3Reliability
If finger beds are arranged on the steering wheel rim for continuous monitoring, then the driver's condition can be monitored continuously, but the visual impression is adversely affected and structural implementation becomes complicated
Solution Approach 1:
The patent replaces the mechanical contact-based photoplethysmographic sensor (finger bed) with an optical detection system using a camera and image processor. This substitution eliminates the need for physical contact points on the steering wheel, allowing continuous monitoring without compromising visual appearance or requiring complex structural modifications to the steering wheel assembly.
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 provides quick, reliable, and cost-effective detection of physiological parameters like heart rate, reducing the complexity and cost of previous methods while maintaining high resolution and reliability, even in low light conditions.
Implementation Method 1
a green bandpass filter is provided which has green and transparent filter pixels
Implementation Method 2
the green components of several individual images of the head of the vehicle driver of the facial area are recorded and stored as image data
Implementation Method 3
the plethysmographic size is determined from the stored image data using a mathematical algorithm
Data Source
Figure 1
Figure 2~4
AI summary
The invention relates to a method for identifying the state of a driver (2) of a motor vehicle (1) by generating a plethysmographic variable which indicates the physiological state of said vehicle driver (2), preferably the heart rate, using a sensor (3) arranged in said vehicle (1). According to the invention, the sensor is designed as a monochrome imaging sensor (3) for capturing an image of the vehicle driver's (2) head (2a), a structured green filter (4, 4a) is provided which comprises green and transparent filter pixels (4b, 4c), the facial region of the vehicle driver (2) is detected from the image-capture of the head (2a), the green portions of the facial region are measured from a plurality of individual images of the vehicle driver's (2) head (2a) and stored as imaging data over a predetermined time period in each case, and the plethysmographic variable is determined from this stored imaging data using a mathematical algorithm.