Large-Scale Displacement Measurement With Micrometer-Level Accuracy Using MIMO FMCW Radar

Due to its excellent environmental adaptability, large detection range, and multitarget measurement, displacement measurement with multiple-input multiple-output (MIMO) frequency-modulated continuous-wave (FMCW) radar has shown enormous potentiality. However, when the target has large-scale displacement, it will inevitably cross the range units and angle units, resulting in additional phase jumps and the failure of the existing measurement method. In this article, a novel ridge demodulation (RDM) method is proposed for large-scale displacement measurement. The approach leverages the range-time ridge and angle-time ridge to estimate the motion trend of the target, enabling to construct the demodulation operator and correspondingly demodulate the baseband signal. With rigorous mathematical derivation, it is demonstrated that the target to be measured will be demodulated into the main lobe of the sinc function, and there is no phase jump in it. Interferometric phase evolution tracking is performed on the zeroth range unit and the zeroth angle unit, which is used to extract the displacement of the target to be measured. Finally, simulations and experiments in various scenarios demonstrate that the proposed RDM method can effectively eliminate the errors and distortion caused by the target crossing range and angle units, offering a promising approach for accurate large-scale displacement measurement with MIMO FMCW radar.