Coordinated Nodding of a Two-Dimensional Lidar for Dense Three-Dimensional Range Measurements

Sensing technology is an integral part of any autonomous system. In particular, two-dimensional (2-D) range sensors have played a critical role in localization, mapping, and other sensing tasks in robotics. But, 2-D measurements provide limited information about the environment, while 3-D range sensors provide a better understanding of the environment for the robot to make crucial decisions. However, 3-D range sensors presently available in market are too costly to be deployed by small robots and in large numbers. Therefore, we introduce a novel low cost 3-D range sensor, developed using an affordable 2-D lidar. A high speed servo is used to nod the lidar and generate 3-D perception of surrounding environment. We developed a mathematical model of the dynamics of the sensor system to prove results of unique point set registration of a 3-D surface while mounted on a robot. The proposed 3-D laser sensor is novel in the way the horizontal and vertical angle are coordinated to produce unique dense scans. In addition, we propose an optimal nodding scheme such that the laser beams cover the whole scan window in the best possible manner. Real-time environment reconstruction has been performed by mounting it on a mobile robot within an indoor environment.