Dynamic Illumination Control for Remote PPG Skin Orientation
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Solution Overview
Problem
Existing vital sign monitoring systems using remote photoplethysmography face challenges with motion robustness, especially when no dominant light source is present, and illumination conditions are not optimal for all skin types or body postures, leading to suboptimal signal quality due to changes in skin orientation relative to the illumination.
Innovation Solution
A device and method that include an orientation estimation unit to determine the skin region's orientation and a control unit to adjust the illumination unit, ensuring optimal illumination angles to minimize the impact of skin orientation changes, thereby improving signal quality and robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fixed illumination is used for remote PPG monitoring, then device complexity is reduced, but measurement precision deteriorates due to skin orientation changes
Solution Approach 1:
The illumination system transitions from fixed to dynamic control by adjusting illumination angles based on real-time skin surface orientation detection. The control unit modifies illumination parameters adaptively to maintain optimal measurement conditions despite subject movement, thereby resolving the contradiction between device simplicity and measurement accuracy.
Solution Approach 2:
The system implements feedback control by detecting skin surface orientation and using this information to adjust illumination angles. The orientation detection unit provides continuous feedback to the control unit, which then modifies illumination parameters to compensate for skin orientation changes, maintaining measurement precision without excessive complexity.
2Area of stationary object
If illumination angle is increased to cover larger skin area, then area of illumination is improved, but measurement precision deteriorates due to reduced irradiance
Solution Approach 1:
Instead of uniformly illuminating a large area at low intensity, the system focuses illumination on the specific skin region of interest with optimized angle and intensity. The orientation-based control ensures concentrated irradiance on the target area, maintaining high signal quality while covering sufficient measurement area.
3Ease of operation
If no orientation compensation is applied, then ease of operation is maintained, but reliability deteriorates during subject movement
Solution Approach 1:
The system performs self-adjustment by automatically detecting skin orientation and compensating for it without requiring external intervention. The orientation detection and illumination control work together to maintain measurement reliability during movement, while the automated nature preserves ease of operation.
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 results in more accurate and robust vital sign measurements by maintaining consistent irradiance and reducing noise from subject movements, even in varying illumination conditions, enhancing the reliability of heart rate, respiratory rate, and other vital sign extractions.
Implementation Method 1
a detection unit for receiving light in at least one wavelength interval reflected from a skin region of a living being and for generating an input signal from the received light
Implementation Method 2
receiving light in at least one wavelength interval reflected from a skin region of a living being
Data Source
AI summary
The present invention relates to a device, system and method for obtaining vital sign related information of a living being (3). The proposed device comprises an input unit (12) for receiving an input signal (32) generated from light (31) received in at least one wavelength interval reflected from a skin region (2) of a living being (3), said input signal representing vital sign related information from which a vital sign of the living being can be 5 derived, a processing unit (14) for processing the input signal (32) and deriving vital sign related information (36) of said living being from said input signal (32), an orientation estimation unit (16) for estimating the orientation of said skin region (2), and a control unit (18) for controlling an illumination unit (40) for illuminating said skin region (3) with light (41) to illuminate said skin region (2) based on the estimated orientation of said skin region 10 (2) and/or for controlling said processing unit to derive vital sign related information (36) from said input signal obtained during time intervals selected based on the estimated orientation of said skin region (2).