A method to detect stairs with three-dimensional scanning for hexapod robot stair climbing

This paper presents a novel stair recognition method by utilizing three-dimensional (3D) scanning for a hexapod robot to climb stairs. The method is based on the premise that stairs are composed of several parallel planar surfaces. A 3D laser range finder (LRF) system equipped on a hexapod robot is developed for performing 3D scanning. The algorithm can be divided into two procedures. At first, detecting the edge points of stair tread surfaces is performed in 2D range images. In order to enhance the robustness of the method and extract the edges more accurately, edge point searching is executed between neighbouring scan planes. Next, the extraction of the tread surfaces is carried out by using these detected edge points in 3D space. The performance of the proposed method is investigated through various experiments. As the experimental results demonstrate, the method is sufficient accurate to detect the tread surfaces and useful for a hexapod robot to climb the stair.