Non-Contact Vital Signs Monitoring for Multiple Subjects Using a Millimeter Wave FMCW Automotive Radar

Technology for in-cabin non-contact monitoring of driver vital signs is a growing area of interest for automotive applications. This has been spurred in part by successful demonstrations of remote sensing of human physiological motion using radar, for healthcare applications. However, most reported physiological radar results have focused on the use of continuous wave radar operating between the 2.4 GHz up to 24 GHz, to monitor a single, isolated subject. There is a recent paradigm shift in the automotive radar industry towards the use of W-band frequency modulated continuous wave radar. This research investigates the feasibility of extracting vital signs information for both single and multi-subject scenarios, utilizing a newly developed 76–81 GHz FMCW single channel architecture automotive radar. Chirp parameters and signal processing steps were developed to extract phase information for signals reflected from tiny movement of a subject's chest surface. Beam steering techniques were used to isolate the respiratory signatures for individual subjects from radar signals reflected simultaneously from multiple subjects. Experimental results showed that independent respiratory signatures could be isolated and measured for subjects separated by a 30° angular discrimination limit.