Simplified Method of Time-Domain Displacement Motion Recovery Using Doppler Radar Sensor

Non-contact accurate detection system of displacement motion has a very wide range of application requirements and potential in medical health and elderly care, especially in vital signs. However, the system of radar-based precision demodulation is easily disturbed by nonlinear factors; it's also hard to achieve high linearity time-domain demodulation with low-complexity demodulation, which limits the application of radar-based detection method in practice. Based on the K-band Doppler radar sensor, this paper introduces the arc-chord approximation and automatic segmentation algorithms to present a simplified and robust demodulation system, which can achieve accurate time-domain detection of arbitrary displacement motion. Both simulation and experiments are conducted in this paper to show the effectiveness of our method. In the experiments, our method can recover 3.67-mm triangle displacement with the accuracy of relative root mean square error 4.47%. What’s more, the proposed method can recover vital sign with strong noise while traditional phase demodulation fails.