Human Target Detection, Tracking, and Classification Using 24-GHz FMCW Radar

This paper presents a millimeter-wave radar in the 24-GHz ISM band for detection, tracking, and classification of human targets. Linear frequency modulation of the transmit signal and two receive antennas enable distance and angle measurements, respectively. Multiple consecutive frequency chirps are used for target velocity calculation. Hardware as well as firmware concepts of the proposed system are described in detail. Various algorithms for human detection and tracking are investigated and combined into a new signal processing routine optimized for compactness and low power to run on a microcontroller. In addition, a novel Doppler-compensated angle-of-arrival estimation method and a one-class support vector machine for human classification are proposed to further enhance the human detection and tracking performance. The achieved performances of the designed hardware and the implemented algorithm are verified in extensive measurements. The distance and angle errors of the realized radar sensor are at most 25 cm along a measurement range of 18 m and 10° for a two-sided angle sweep of 65°, respectively. The achieved range resolution is 0.9 m. The dedicated verifications of the most important signal processing routines are presented to verify their functionality and experiments with several human targets that illustrate the performance and limits of the overall tracking algorithm. It is shown that range, velocity, and angle of up to five humans are correctly detected and tracked. The presented one-class classifier successfully distinguishes the human targets from other quasi-static targets, such as trees and shadowing effects of human subjects on walls.