Reshaping Field of View and Resolution with Segmented Reflectors: Bridging the Gap between Rotating and Solid-State LiDARs

Abstract

This paper describes the first simulations and experimental results of a novel segmented Light Detection And Ranging (LiDAR) reflector. Large portions of the rotating LiDAR data are typically discarded due to occlusion or a misplaced field of view (FOV). The proposed reflector solves this problem by reflecting the entire FOV of the rotating LiDAR towards a target. Optical simulation results, using Zemax OpticStudio, suggest that adding a reflector reduces the range of the embedded LiDAR with only 3.9 %. Furthermore, pattern simulation results show that a radially reshaped FOV can be configured to maximize point cloud density, maximize coverage, or a combination. Here, the maximum density is defined by the number of mirror segments in the reflector. Finally, a prototype was used for validation. Intensity, Euclidean error, and sample standard deviation were evaluated and, except for reduced-intensity values, no significant reduction in the LiDAR’s performance was found. Conversely, the number of usable measurements increased drastically. The mirrors of the reflector give the LiDAR multiple viewpoints to the target. Ultimately, it is argued that this can enhance the object revisit rate, instantaneous resolution, object classification range, and robustness against occlusion and adverse weather conditions. Consequently, the reflector design enables long-range rotating LiDARs to achieve the robust super-resolution needed for autonomous driving at highway speeds.

Calibration of Planar Reflectors Reshaping LiDAR’s Field of View

“…The impact of planar reflectors on another popular LIDAR (Velodyne VLP-16) was investigated in detail in the paper [ 19 ]. In their work, the authors investigated power loss and LiDAR’s scanning pattern after FOV reshaping.…”

“…The authors Aalerud et al [ 19 ] proposed a method for the simulation and design of a radially reshaped field of view. This work shows great potential for an increased number of usable measurements.…”

Design and Calibration of Plane Mirror Setups for Mobile Robots with a 2D-Lidar

“…The resulting point cloud data after the transformation depend on the distance and angular orientation of the mirror that reflects the light. The algorithm of this point cloud transformation as presented in Formulas (1) to (4) was taken from [ 12 ] (p. 5), but the formula (2) for was corrected. For a visualization of the underlying 3D geometry, the figure in the given reference can be used.…”

“…In a paper by Aalerud et al [ 12 ], the FOV of a 3D spinning Lidar was reshaped by means of eight plane mirrors. The goal was to generate a similar FOV to that of a 3D flash Lidar, but using a 3D spinning Lidar, and to improve the spatial resolution.…”

“…The goal was to generate a similar FOV to that of a 3D flash Lidar, but using a 3D spinning Lidar, and to improve the spatial resolution. This group also presented mechanical design considerations for the placement of the mirrors and performance figures of the resulting prototype, and they stressed the need for a calibration method [ 12 ] (p. 22) to increase the precision of the measurement.…”