Map Building for a Terrain Scanning Robot

This paper presents the application of an image registration method for a mobile manipulator. The robot is used for scanning natural terrain and detecting metal objects hidden beneath the terrain surface (e.g., landmines) using a metal detector. The range image may be interpreted for visual servoing, map building and path planning, or object recognition. In this work, the image is used to build a terrain map for obstacle free path planning. Because the working area of the robot is extremely dynamic (i.e., not only the robot travels but also the environment is also subject to change) an active range sensing method is selected to provide the range image. The range values are acquired using a laser range finder with a rotating mirror for scanning so that sensor fusion in the form of collecting sensor readings over an extended period of time is required. In addition, range readings of two ultrasonic range finders are fused at signal level to tackle both sensor imperfection and environmental illumination that induce uncertainty at the system. In this paper, we explain the use of a real-time programming platform that executes an on-line mapbuilding process in parallel for robot manipulation and control. KeywordsMobile manipulator, path planning, map building, range image, visual servoing, and sensor fusion.