Provable strategies for vision-guided exploration in three dimensions

An approach is presented for exploring an unknown, arbitrary surface in three-dimensional (3D) space by a mobile robot. The main contributions are (1) an analysis of the capabilities a robot must possess and the trade-offs involved in the design of an exploration strategy, and (2) two provably-correct exploration strategies that exploit these trade-offs and use visual sensors (e.g., cameras and range sensors) to plan the robot's motion. No such analysis existed previously for the case of a robot moving freely in 3D space. The approach exploits the notion of the occlusion boundary, i.e., the points separating the visible from the occluded parts of an object. The occlusion boundary is a collection of curves that "slide" over the surface when the robot's position is continuously controlled, inducing the visibility of surface points over which they slide. The paths generated by our strategies force the occlusion boundary to slide over the entire surface. The strategies provide a basis for integrating motion planning and visual sensing under a common computational framework.<<ETX>>