Static Background Removal in Vehicular Radar: Filtering in Azimuth-Elevation-Doppler Domain

Anti-collision assistance (as part of the current push towards increasing vehicular autonomy) critically depends on accurate detection/localization of moving targets in vicinity. An effective solution pathway involves removing background or static objects from the scene, so as to enhance the detection/localization of moving targets as a key component for improving overall system performance. In this paper, we present an efficient algorithm for background removal for automotive scenarios, applicable to commodity frequency-modulated continuous wave (FMCW)-based radars. Our proposed algorithm follows a three-step approach: a) preprocessing of back-scattered received radar signal for 4-dimensional (4D) point clouds generation, b) 3-dimensional (3D) radar ego-motion estimation, and c) notch filter-based background removal in the azimuth-elevation-Doppler domain. To begin, we model the received signal corresponding to multiple-input multiple-output (MIMO) FMCW transmissions and develop a signal processing framework for extracting 4D point clouds. Subsequently, we introduce a robust 3D ego-motion estimation algorithm that accurately estimates source radar velocity, accounting for measurement errors and Doppler ambiguity, by processing the point clouds. Additionally, our algorithm leverages the relationship between Doppler velocity, azimuth angle, elevation angle, and radar ego-motion velocity to identify the background clutter spectrum and employ notch filters for its removal. The performance of our algorithm is evaluated using both simulated data and experiments with real-world data. By offering a fast and computationally efficient solution, our approach contributes to a potential pathway for challenges posed by non-homogeneous environments and real-time processing requirements.