Automatic Spatial Calibration of Near-Field MIMO Radar With Respect to Optical Depth Sensors
This addresses a critical bottleneck for autonomous systems requiring precise sensor fusion in near-field applications, representing a novel method for a known challenge.
The paper tackles the problem of mutual sensor calibration between MIMO radar and optical depth sensors in the near field, proposing a joint calibration approach that achieves efficient and accurate spatial alignment validated with two depth sensing technologies.
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.