LiDAR is a method of determining distances by hitting a target with laser light and measuring its reflection with a sensor. The technology is used for any number of applications, including autonomous vehicles for obstacle avoidance and robotics where it's employed for navigation (area mapping) and object classification. For some mobile robots, omnidirectional 3D LiDAR is typically mounted to the front of the unit to limit interference from other equipment, but doing so limits its measurement area by half because the robot's body blocks the laser.
To help mitigate that issue, researchers from the University of Tokyo and Tohoku University were able to expand the LiDARs measurement area by installing mirrors to its blind spots on the robot's housing.
According to the team, "Installing mirrors behind LiDAR enables the invalidated area behind the LiDAR to be utilized. Hence, it is possible to acquire environmental information within a broader range in front of the robot. Particularly, by expanding the measurement area to the lower front of the robot, it is possible to obtain terrain information such as a shape of the stairway or large obstacles in the short distance of the robot."
Roboticists can't just slap any mirrors onto the robot and improve its LiDAR measurement and range; some requirements need to be implemented for it to work correctly. Providing an overlap between the desired area to be observed and the detection area by the reflected laser light needs to be maximized. The overlap between the detection area of standard laser rays and the reflective area must be minimized, and flat mirrors are required to avoid any distortion of the laser light, which could produce anomalies. Finally, the mirrors need to be mounted on the same base where the LiDAR is mounted to avoid vibration during movement.
The researchers tested their setup using a series of calculations to find the best angles for the mirrors to positioned that would warrant higher area measurements. The found while their calculations were slightly different from what they expected, it did increase LiDARs accuracy.