Accurate Heart Rate Measurement Across Various Body Postures Using FMCW Radar

In this paper, a new heart rate measurement technology with high accuracy is proposed by using the frequency modulated continuous wave (FMCW) radar in the case of body-limb motions. Using this technology to detect human heart rate can not only filter the interference of various stationary clutters in the radar field of view but also effectively eliminate the interference caused by body motion. The main contributions of this paper include the establishment of the hybrid echo signal model for motion-stationary objects and the complex signal model for multi-limb composite motions. Based on the proposed complex signal model, a periodic signal enhancement algorithm together with the optimizing equation for heart rate measurement is proposed to acquire heart rate by parameter optimization. Both the simulation and experimental results show that the proposed technology can achieve accurate measurement of heart rate even when the human body is in the state of various multi-limb movements. Accuracy analysis compared to the mean value of the results of electrocardiography (ECG) shows that the root mean square error is less than 3.5 bpm in stationary scenarios within 2 m and less than 4.2 bpm in body motion scenarios within 1 m. Additionally, simulations are conducted for radars operating at 5.8 GHz and 77 GHz frequencies. The results show that the proposed technology can be well applied to vital sign monitoring for radars operating across various frequency bands.