A new height-estimation method using FMCW radar Doppler beam sharpening

Abstract

This paper presents a new method for estimating the height of extended objects using a Frequency Modulation Continuous Wave (FMCW) automotive radar. The proposed algorithm exploits the frequency shift caused by the Doppler effect while approaching stationary objects, to estimate target heights. Thus, the algorithm does not require multiple vertical antennas for height finding. First, the measured radial velocity is derived using sensor target geometry, then, a target height is formulated as a function of target range, vehicle velocity and elevation angle component of the measured radial velocity. Next, the processing pipeline of the proposed Doppler Beam Sharpening (DBS) algorithm is described, and the three dimensional (3D) high resolution RELAX is applied to collected radar data to provide accurate range, azimuth angle and Doppler estimations of the detected targets. Finally height measurement results of an entrance gate 4.5 m high are presented and discussed. The results show that the proposed height finding algorithm can achieve a root mean squared error of 0.26 m.