System and method for capturing and decontaminating photoplethysmopgraphy (PPG) signals in a vehicle

• US 10,213,162 B2
• Filed: 08/12/2016
• Issued: 02/26/2019
• Est. Priority Date: 04/06/2013
• Status: Active Grant

• Current Assignee: Honda Motor Co., Ltd. (Honda Motor Company)
• Original Assignee: Honda Motor Co., Ltd. (Honda Motor Company)
• Inventors: Fung, Kin C., Dick, Timothy J., Palande, Dhanashree
• Primary Examiner(s): Yi, Roy Y
• Assistant Examiner(s): Aiello, Jeffrey
• Application Number:
  US15/235,808
• Publication Number:
  US 20160345907A1
• Time in Patent Office: 928 Days
• CPC Class Codes: A61B 5/0059 using light, e.g. diagnosis by transillumination, diascopy, fluorescence A61B5/0093, A61B5/1455, A61B5/02416 and A61B5/0261 take precedence
• CPC Class Codes: A61B 5/0077 Devices for viewing the surface of the body, e.g. camera, magnifying lens
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/0261 using optical means, e.g. infrared light
• CPC Class Codes: A61B 5/0295 using plethysmography, i.e. measuring the variations in the volume of a body part as modified by the circulation of blood therethrough, e.g. impedance plethysmography
• CPC Class Codes: A61B 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• CPC Class Codes: A61B 5/11 Measuring movement of the entire body or parts thereof, e.g. head or hand tremor, mobility of a limb for measuring pulse A61B5/02 ;A61B5/1038 takes precedence; motion detection to correct for motion artifacts in physiological signals A61B5/721
• CPC Class Codes: A61B 5/117 Identification of persons methods or arrangements for recognising patterns, e.g. fingerprints, G06F18/00, G06V40/00; identification of persons by analysing their voice or speech G10L17/00
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: A61B 5/18 for vehicle drivers or machine operators
• CPC Class Codes: A61B 5/6893 Cars
• CPC Class Codes: A61B 5/721 using a separate sensor to detect motion or using motion information derived from signals other than the physiological signal to be measured
• CPC Class Codes: B60R 25/25 using biometry
• CPC Class Codes: G06F 2218/10 by analysing the shape of a waveform, e.g. extracting parameters relating to peaks
• CPC Class Codes: G06F 2218/12 Classification; Matching
• CPC Class Codes: G06V 40/15 Biometric patterns based on physiological signals, e.g. heartbeat, blood flow

Abstract

A system and method for processing photoplethysmography (PPG) signals in a vehicle. The system and method include receiving a PPG waveform signal from an optical sensor. The system and method also include processing a PPG measurement signal based on the PPG waveform signal. The system and method additionally include receiving a noise waveform signal from at least one of: a seat assembly sensor, a vehicle sensor, and a vehicle system. Additionally, the system and method include processing a motion artifacts measurement signal based on the noise waveform signal. The system and method further include processing a refined PPG signal to suppress the motion artifacts measurement signal from the PPG measurement signal.

Claims

1. A computer-implemented method for processing photoplethysmography (PPG) signals in a vehicle, comprising:

receiving a plurality of PPG waveform signals output from a plurality of optical sensors included in one or more sensor assemblies;

receiving a plurality of pressure measurement signals output from a plurality of pressure sensors included in the one or more sensor assemblies;

selecting optimum PPG waveform signals from the plurality of PPG waveform signals based on the plurality of pressure measurement signals and based on a position of a driver in the vehicle;

aggregating the optimum PPG waveform signals into a PPG measurement signal;

outputting the PPG measurement signal to determine a state of the driver; and

controlling at least one vehicle system of the vehicle based on the driver state of the driver.

2. The computer-implemented method of claim 1, wherein selecting the optimum PPG waveform signals includes determining one or more of the plurality of pressure sensors sensing the highest pressure based on the plurality of pressure measurement signals.

3. The computer-implemented method of claim 2, further including selecting the optimum PPG waveform signals based on a location of the plurality of optical sensors relative to a location of the one or more of the plurality of pressure sensors sensing the highest pressure.

4. The computer-implemented method of claim 2, further including selecting the optimum PPG waveform signals output from one or more of the plurality of optical sensors included within the one or more sensor assemblies also including the one or more of the plurality of pressure sensors sensing the highest pressure.

5. The computer-implemented method of claim 1, wherein selecting the optimum PPG waveform signals based on the position of the driver further includes determining a location of a vehicle seat in the vehicle having the highest amount of contact with the driver based on the position of the driver, and selecting PPG waveform signals output from one or more of the plurality of optical sensors included within sensor assemblies located at the location of the vehicle seat.

6. The computer-implemented method of claim 1, wherein selecting the optimum PPG waveform signals based on the position of the driver further includes identifying movement of the driver and selecting PPG waveform signals output from one or more of the plurality of optical sensors included within sensor assemblies at a location in a vehicle seat proximate to a body part of the driver exhibiting the least movement.

7. The computer-implemented method of claim 1, wherein selecting the optimum PPG waveform signals based on the position of the driver further includes selecting the PPG waveform signals output from one or more of the plurality of optical sensors included within sensor assemblies located in a vehicle seat proximate to a left leg of the driver.

8. The computer-implemented method of claim 1, further including processing a refined PPG signal to suppress motion artifacts from the PPG measurement signal by filtering a segment of the PPG measurement signal that is attributed to motion artifacts represented within a motion artifacts measurement signal.

9. The computer-implemented method of claim 1, wherein selecting the optimum PPG waveform signals further includes determining the position of the driver based on images of the driver received from one or more cameras.

10. The computer-implemented method of claim 9, further including determining characteristics of clothing worn by the driver based on the images, the characteristics including at least one of color, material, clothing type, and a location of clothing on the driver.

11. The computer-implemented method of claim 10, further including controlling an intensity of optical sensors included within the plurality of optical sensors based on the characteristics of clothing and a location of the optical sensors.

12. The computer-implemented method of claim 10, further including controlling an intensity of optical sensors included within the plurality of optical sensors based on the clothing type at a location of clothing on the legs of the driver.

13. A system for processing photoplethysmography (PPG) signals in a vehicle, comprising:

a computing device that includes a memory storing instructions that are executed by a processor; and

a PPG determinant module that is included as a module of the computing device that;

receives a plurality of PPG waveform signals output from a plurality of optical sensors included in one or more sensor assemblies,

receives a plurality of pressure measurement signals output from a plurality of pressure sensors included in the one or more sensor assemblies,

evaluates the plurality of PPG waveform signals to determine a set of consistent PPG waveform signals including optimum PPG waveform signals selected from the plurality of PPG waveform signals based on the plurality of pressure measurement signals and based on a position of a driver in the vehicle,

aggregates the set of consistent PPG waveform signals into a PPG measurement signal;

outputs the PPG measurement signal to the computing device; and

controls at least one vehicle system of the vehicle based on the driver state of the driver.

14. The system of claim 13, wherein the PPG determinant module determines one or more of the plurality of pressure sensors sensing the highest pressure based on the plurality of pressure measurement signals and selects the optimum PPG waveform signals based on a location of the plurality of optical sensors relative to a location of the one or more of the plurality of pressure sensors sensing the highest pressure.

15. The system of claim 13, wherein the PPG determinant module discards PPG waveform signals from the a set of consistent PPG waveform signals based a location of the plurality of optical sensors relative to the position of the driver.

16. The system of claim 13, further including one or more cameras for capturing images of the driver, wherein the PPG determinant module determines characteristics of clothing worn by the driver based on the images, and controls an intensity of optical sensors included within the plurality of optical sensors based on the characteristics of clothing and a location of the optical sensors.

17. A non-transitory computer-readable storage medium storing instructions that when executed by a computer, which includes a processor perform a method, the method comprising:

receiving a plurality of PPG waveform signals output from a plurality of optical sensors included in one or more sensor assemblies;

receiving a plurality of pressure measurement signals output from a plurality of pressure sensors included in the one or more sensor assemblies;

selecting optimum PPG waveform signals from the plurality of PPG waveform signals based on the plurality of pressure measurement signals and based on a position of a driver in a vehicle;

aggregating the optimum PPG waveform signals into a PPG measurement signal;

outputting the PPG measurement signal to determine a state of the driver; and

controlling at least one vehicle system of the vehicle based on the driver state of the driver.

18. The non-transitory computer-readable medium of claim 17, wherein selecting the optimum PPG waveform signals includes selecting PPG waveform signals output from one or more of the plurality of optical sensors that are located in proximity to one or more of the plurality of pressure sensors sensing the highest pressure.

19. The non-transitory computer-readable medium of claim 17, further including determining characteristics of clothing worn by the driver based on images received from one or more cameras, the characteristics including at least one of color, material, clothing type, and a location of clothing on the driver.

20. The non-transitory computer-readable medium of claim 19, further including

controlling an intensity of optical sensors included within the plurality of optical sensors based on the characteristics of clothing and a location of the optical sensors.