Automatic planning of laser measurements for a large-scale environment using CPS-SLAM system

In recent years, several low-cost 3D laser scanners are being brought to the market and 3D laser scanning is becoming widely used in many fields. For example, 3D modeling of architectural structures or digital preservation of cultural heritages are typical applications for 3D laser scanning. Despite of the development of light-weight and high-speed laser scanners, however, the complicated measurement procedure and long measurement time are still a heavy burden for the widespread use of laser scanning. We have proposed a robotic 3D scanning system using multiple robots named CPS-SLAM, which consists of parent robots with a 3D laser scanner and child robots with target markers. In this system, a large-scale 3D model can be acquired by an on-board 3D laser scanner on a parent robot from several positions determined precisely by the localization technique using multiple robots named Cooperative Positioning System, CPS. Therefore, this system enables to build a 3D model without complicated post-processing procedures such as ICP. In addition, this system is an open-loop SLAM system and a quite precise 3D model can be obtained without closed loops. This paper proposes an automatic planning technique of a laser measurement for CPS-SLAM. By planning a proper scanning strategy depending on a target structure, it is possible to perform laser scanning efficiently and accurately even for a large-scale and complex environment. Proposed technique plans an efficient scanning strategy automatically by taking account of several criteria, such as visibility between robots, error accumulation, and efficient traveling. We conducted computer simulations and outdoor experiments to verify the performance of the proposed technique.