Cost-effective Mobile Solution for Autonomous and Continuous Vital Signs
Monitoring
Abstract
The Covid-19 Pandemic has renewed interest in contactless vital signs
monitoring using state-of-the-art computer vision, which can efficiently
screen for symptoms while reducing the risk of disease transmission.
Despite the promising perfor- mance, the use of static camera setups
requires subjects to remain static inside a field of view (FoV) for a
pre-specified duration. Due to inconsistent ambient environmental
conditions, the transit of individuals through the FoV, and the time it
may take to triage individuals, the widespread adoption of static camera
systems to continuously monitor vital signs has had suboptimal uptake.
Robotic systems enable autonomous and continuous monitoring, but these
require expensive cameras, computers, and robotic platforms, limiting
widespread deployment. In response, we propose a cost-effective and
scalable robotic solution consisting of a suite of commercial,
off-the-shelf wireless cameras for capturing photoplethysmography (PPG)
on ambulatory subjects linked to a single computer that supervises the
cameras to compute the vital signs of subjects. Throughout a set of
careful investigations of each individual step of the wireless machine
vision camera and computer, bottlenecks constraining wireless
live-streaming of high-quality PPG information are identified and those
are addressed by a hybrid centralized/decentralized wireless machine
vision protocol. Our results demonstrate that the proposed
cost-effective wireless camera achieves equivalent remote-PPG accuracy
to its costly, USB3 counterparts (mean error: 5.0 BMP vs. 4.7 BPM) by
means of the hybrid camera protocol which boosts the overall frame rate
to 17 FPS. In contrast, using the standard method that captures the PPG
with the same spatial resolution can only achieve 1 FPS. In addition,
this work also elucidates how varying the distance, image pixel density,
frame rate, image compression, image downsampling, and color depth
affect the rPPG performance. For each of the effects, we also discuss
potential solutions for the cost-effective setup.