In-cabin 120 GHz radar system for functional human breathing monitoring in a 3D scenario

Abstract

Driving is one of the activities that takes a significant part of a person’s time, that is why monitoring vital signs is useful for the wellness of the occupants of the vehicle. One of the vital signs that provides more information about the state of the person, is the functional breathing. Compared to other vital signs indicators, breathing is more sensitive to cardiovascular events, emotional stress, physical exertion, or fatigue induced by long time driving, seen as variations in chest and abdomen elongation modes. Functional monitoring is a tool that can transcend, from measurement and detection to emotional changes through feedback of sounds, images, or videos to the driver. In this regard, this work proposes an imaging radar system to generate a topographic map with elongation modes of the driver’s chest and abdomen, at 120 GHz. Numerical simulations have been deployed in order to reconstruct the image from the receiver signal in the radar using spatial convolution. Furthermore, a metronome has been used to calibrate the radar for elongations measuring with respect to time, and finally, the system has been tested experimentally in an adult person, to generate a preliminary topographic map that allows matching the chest elongation modes to breathing patterns.