High-Precision Vital Signs Monitoring Method Using a FMCW Millimeter-Wave Sensor

Abstract

The method of using millimeter-wave radar sensors to detect human vital signs, namely respiration and heart rate, has received widespread attention in non-contact monitoring. These sensors are compact, lightweight, and able to sense and detect various scenarios. However, it still faces serious problems of noisy interference in hardware, which leads to a low signal-to-noise ratio (SNR). We used a frequency-modulated continuous wave (FMCW) radar sensor operating at 77 GHz in an office environment to extract the respiration and heart rate of a person accustomed to sitting in a chair. Indeed, the proposed signal processing includes novel impulse denoising operations and the spectral estimation decision method, which are unique in terms of noise reduction and accuracy improvement. In addition, the proposed method provides high-quality, repeatable respiration and heart rates with relative errors of 1.33% and 1.96% on average compared with the reference values measured by a reliable smart bracelet.

Systematic Literature Review Regarding Heart Rate and Respiratory Rate Measurement by Means of Radar Technology

“…The distance between the test persons and the radar varied between 0.15 and 30 m. In 72 studies, measurements were performed at a distance of up to 1 m [2,5,10-14, 16-19,22,23,25-27,30,33-40, 42-45,48,51,55,57-59,61,63-65,70,74-80,80-84,86,92,93,95-97,100-103,107-111,113,115-117,120]. In 39 studies, the distance was between 1 and 10 m [3,10,15,20,24,31,32,37,44,[46][47][48][49][50]53,56,59,60,62,66,68,69,[71][72][73]76,79,81,85,87,88,90,91,93,94,109,112,115,119], and in 3 studies, it exceeded 10 m [31,49,81]. A total of 13 studies did not contain any information on the distance [21,28,41,54,…”

An improved error cancellation method for high speed FMCW radar based on FPGA platform

“…With the continuous improvement of intelligent requirements in the industrial field, sensor detection technology is an important way to collect information and an important basic condition to realize intelligence. As a kind of radar sensing technology, frequency modulated continuous wave (FMCW) radar has been widely used due to its advantages of low cost, high resolution, and adaptability to complex working environments, [1][2][3][4] including high-speed moving target recognition, life detection, automatic driving, and so on. [5][6][7][8] However, due to the noise in the environment and the influence of the system hardware itself, the signal measured by the radar sensor has large noise, which affects the final solution accuracy.…”

Respiration and Heart Rate Monitoring in Smart Homes: An Angular-Free Approach with an FMCW Radar

“…This can be achieved by standing in front of the radar sensor or lying down on a bed equipped with radar technology on the ceiling. In the majority of works, the individual in question assumes an anterior position to the radar without any angular orientation [ 9 , 10 , 11 , 12 , 13 , 14 , 15 ]. The ability to monitor vital signs from various angular positions presents a significant advantage in the context of smart home applications.…”

“…As mentioned, in most papers, it is assumed that the living subject is in front of the radar (without any angular position). In the work conducted by authors in [ 10 , 11 , 12 ], commercial FMCW radars were employed to extract physiological indicators from varying distances of up to 2.5 m, without angular orientation and with offline processing. In the study outlined in [ 14 , 15 ], measurements were conducted to monitor vital signs of an individual who lay on a bed in front of the radar.…”