Autonomous Exploration for 3D Mapping Using a Mobile Manipulator Robot with an RGB-D Camera

This study focuses on an unknown environment exploration method for generating a 3D occupancy grid map using a mobile manipulator robot with an RGB-Dcamera. To determine themoving destination and camera pose, a boundary between known and unknown regions is detected as a frontier, and a frontier observation map is created to record the number of frontiers that can be observed at a certain position and pose. Subsequently, based on the frontier observation map, an approach to efficiently generate a map in a short travel distance and time by actively changing the camera posture while moving is explored. However, if the robot simply sets the position by using the largest number of frontiers as the destination, it may have to move back and forth to the same location many times when missing some frontiers, resulting in more time to generate the map. To solve this problem, a method of modifying the frontier observation map based on the distance and angle to preferentially observe the frontier near the robot and in the direction where the robot is moving, respectively, is proposed. The effectiveness of the modification process in determining the destination in terms of the length of the path traveled and map generation time for several environments is verified by simulations. In addition, the effect of actively changing the camera posture while the robot is moving is evaluated.