Are Doppler Velocity Measurements Useful for Spinning Radar Odometry?

TL;DR

This paper introduces a method to extract Doppler velocity measurements from spinning FMCW radars using a novel firmware modification, demonstrating their usefulness in improving autonomous vehicle odometry, especially in challenging environments.

Contribution

The paper presents a new technique to obtain radial Doppler velocities from spinning radar scans without data association, enhancing odometry robustness in complex scenarios.

Findings

Doppler velocities improve odometry accuracy in geometric environments.

Radial Doppler measurements enable odometry in tunnel-like environments.

The method is validated over 110 km of driving data.

Abstract

Spinning, frequency-modulated continuous-wave (FMCW) radars with 360 degree coverage have been gaining popularity for autonomous-vehicle navigation. However, unlike `fixed' automotive radar, commercially available spinning radar systems typically do not produce radial velocities due to the lack of repeated measurements in the same direction and the fundamental hardware setup. To make these radial velocities observable, we modified the firmware of a commercial spinning radar to use triangular frequency modulation. In this paper, we develop a novel way to use this modulation to extract radial Doppler velocity measurements from consecutive azimuths of a radar intensity scan, without any data association. We show that these noisy, error-prone measurements contain enough information to provide good ego-velocity estimates, and incorporate these estimates into different modern odometry pipelines. We extensively evaluate the pipelines on over 110 km of driving data in progressively more geometrically challenging autonomous-driving environments. We show that Doppler velocity measurements improve odometry in well-defined geometric conditions and enable it to continue functioning even in severely geometrically degenerate environments, such as long tunnels.