Contactless Monitoring Of Human Vitals: A Study With Simultaneous Measurements Using FMCW Radar And Thermal Camera

This paper proposes contactless monitoring of Heart Rate (HR) and Breath Rate (BR) with simultaneous measurements using Frequency Modulated Continuous Wave (FMCW) radar and thermal camera. The radar collects the body movement signals which include Random Body Movements (RBMs). Non-negative Matrix Factorization (NMF) and Wavelet analysis were used on this signal to get the accurate values of HR and BR. Similarly, with thermal imaging, nostril and forehead regions are tracked to estimate the values of BR as well as HR. We conducted an experiment with 50 subjects to find similarities in the performance of radar and thermal camera while measuring HR and BR. Simultaneously, these two methods have been validated with pulse oximeter and visual camera. From the visual camera, we can get the abdominal movements on which the BR can be ascertained whereas pulse oximeter gives us the HR. Radar signals are degraded because of large RBMs whereas thermal signals get distorted because of sudden temperature changes in the surroundings, sweating, and occlusion. We used a Signal Quality Metric (SQM) to ascertain the measurement quality of the vital signs. This SQM-based approach can further be used for sensor fusion to build a robust contactless system to monitor vital signs.Clinical relevance- Contactless and accurate measurement of HR and BR is very essential for continuous and comfortable monitoring of vitals. In this paper, we combine both FMCW radar and thermal camera so that one can complement the other in adverse scenarios on the basis of signal quality.