Ascending stairway modeling from dense depth imagery for traversability analysis

Localization and modeling of stairways by mobile robots can enable multi-floor exploration for those platforms capable of stair traversal. Existing approaches focus on either stairway detection or traversal, but do not address these problems in the context of path planning for the autonomous exploration of multi-floor buildings. We propose a system for detecting and modeling ascending stairways while performing simultaneous localization and mapping, such that the traversability of each stairway can be assessed by estimating its physical properties. The long-term objective of our approach is to enable exploration of multiple floors of a building by allowing stairways to be considered during path planning as traversable portals to new frontiers. We design a generative model of a stairway as a single object. We localize these models with respect to the map, and estimate the dimensions of the stairway as a whole, as well as its steps. With these estimates, a robot can determine if the stairway is traversable based on its climbing capabilities. Our system consists of two parts: a computationally efficient detector that leverages geometric cues from dense depth imagery to detect sets of ascending stairs, and a stairway modeler that uses multiple detections to infer the location and parameters of a stairway that is discovered during exploration. We demonstrate the performance of this system when deployed on several mobile platforms using a Microsoft Kinect sensor.