Continuous-Time Three-Dimensional Mapping for Micro Aerial Vehicles with a Passively Actuated Rotating Laser Scanner

The ability to generate accurate and detailed three-dimensional (3D) maps of a scene from a mobile platform is an essential technology for a wide variety of applications from robotic navigation to geological surveying. In many instances, the best vantage point is from above, and as a result, there is a growing demand for low-altitude mapping solutions from micro aerial vehicles such as small quadcopters. Existing lidar-based 3D airborne mapping solutions rely on GPS/INS solutions for positioning, or focus on producing relatively low-fidelity or locally focused maps for the purposes of autonomous navigation. We have developed a general-purpose airborne 3D mapping system capable of continuously scanning the environment during flight to produce accurate and dense point clouds without the need for a separate positioning system. A key feature of the system is a novel passively driven mechanism to rotate a lightweight 2D laser scanner using the rotor downdraft from a quadcopter. The data generated from the spinning laser is input into a continuous-time simultaneous localization and mapping (SLAM) solution to produce an accurate 6 degree-of-freedom trajectory estimate and a 3D point cloud map. Extensive results are presented illustrating the versatility of the platform in a variety of environments including forests, caves, mines, heritage sites, and industrial facilities. Comparison with conventional surveying methods and equipment demonstrates the high accuracy and precision of the proposed solution.