Automatic Spatial Calibration of Near-Field MIMO Radar With Respect to Optical Depth Sensors

TL;DR

This paper introduces a novel automatic calibration method for near-field MIMO radar and optical depth sensors, enabling precise spatial alignment within decimeters, which is crucial for autonomous applications.

Contribution

It presents a joint calibration pipeline using a custom target for near-field sensor alignment, addressing limitations of target-based methods in the autonomous industry.

Findings

Effective calibration within decimeters range

High accuracy and robustness demonstrated

Compatible with different optical depth sensing technologies

Abstract

Despite an emerging interest in MIMO radar, the utilization of its complementary strengths in combination with optical depth sensors has so far been limited to far-field applications, due to the challenges that arise from mutual sensor calibration in the near field. In fact, most related approaches in the autonomous industry propose target-based calibration methods using corner reflectors that have proven to be unsuitable for the near field. In contrast, we propose a novel, joint calibration approach for optical RGB-D sensors and MIMO radars that is designed to operate in the radar's near-field range, within decimeters from the sensors. Our pipeline consists of a bespoke calibration target, allowing for automatic target detection and localization, followed by the spatial calibration of the two sensor coordinate systems through target registration. We validate our approach using two different depth sensing technologies from the optical domain. The experiments show the efficiency and accuracy of our calibration for various target displacements, as well as its robustness of our localization in terms of signal ambiguities.