US 11,730,427 B2
Systems and methods for autocorrelation based assessment of PPG signal quality
Eliott Jones, Truckee, CA (US); Jean-Francois Knebel, Montricher (CH); Urvan Christen, Pully (CH); Frederic Frappereau, Menlo Park, CA (US); and Patrick Schoettker, Menlo Park, CA (US)
Assigned to BIOSPECTAL SA, Lausanne (CH)
Filed by BIOSPECTAL SA, Lausanne (CH)
Filed on Oct. 27, 2021, as Appl. No. 17/511,550.
Claims priority of provisional application 63/220,369, filed on Jul. 9, 2021.
Claims priority of provisional application 63/107,927, filed on Oct. 30, 2020.
Prior Publication US 2022/0133241 A1, May 5, 2022
Int. Cl. A61B 5/00 (2006.01); G06V 10/56 (2022.01); A61B 5/024 (2006.01); A61B 5/103 (2006.01); G06T 7/90 (2017.01); G06V 10/40 (2022.01); A61B 5/021 (2006.01); A61B 5/026 (2006.01); A61B 5/1455 (2006.01); A61B 5/0225 (2006.01); G06V 40/12 (2022.01)
CPC A61B 5/7221 (2013.01) [A61B 5/0004 (2013.01); A61B 5/0013 (2013.01); A61B 5/0077 (2013.01); A61B 5/0261 (2013.01); A61B 5/02108 (2013.01); A61B 5/02141 (2013.01); A61B 5/02255 (2013.01); A61B 5/02416 (2013.01); A61B 5/1032 (2013.01); A61B 5/6826 (2013.01); A61B 5/6898 (2013.01); A61B 5/7225 (2013.01); A61B 5/7264 (2013.01); A61B 5/742 (2013.01); A61B 5/743 (2013.01); G06T 7/90 (2017.01); G06V 10/40 (2022.01); G06V 10/56 (2022.01); G06V 40/1382 (2022.01); A61B 5/14551 (2013.01); A61B 2560/0223 (2013.01); A61B 2562/0247 (2013.01); A61B 2562/0271 (2013.01)] 10 Claims
OG exemplary drawing
 
1. A method of assessing photoplethysmographic (PPG) signals generated based on transdermal optical data, the method comprising:
acquiring, by a computing device, a sequence of images representing transdermal optical data of a subject;
generating, by the computing device, a sequence of downsampled color frames corresponding to the sequence of images by downsampling a respective color frame for each image of the sequence of images;
generating, by the computing device, a PPG signal using color intensity values corresponding to central image blocks defined across the sequence of downsampled color frames, each color intensity value generated using a corresponding central image block defined in a corresponding downsampled color frame in the sequence of downsampled color frames;
computing, by the computing device, using a sliding window, a plurality of normalized autocorrelation signals of the PPG signal, each normalized autocorrelation signal corresponding to a portion of the PPG signal defined by a corresponding position of the sliding window;
determining, by the computing device, using the plurality of normalized autocorrelation signals, a plurality of quality metrics indicative of a quality of the PPG signal, determining the plurality of quality metrics includes determining, for each normalized autocorrelation signal, a respective peak; and
generating, by the computing device, based on the plurality of quality metrics, an indicator indicative of the quality of the PPG signal,
wherein determining the respective peak for each normalized autocorrelation signal includes:
penalizing correlation values of the normalized autocorrelation signal using powers of corresponding indices; and
identifying an index of the respective peak as an index of a maximum of penalized correlation values.