River mapping from a flying robot: state estimation, river detection, and obstacle mapping

Accurately mapping the course and vegetation along a river is challenging, since overhanging trees block GPS at ground level and occlude the shore line when viewed from higher altitudes. We present a multimodal perception system for the active exploration and mapping of a river from a small rotorcraft. We describe three key components that use computer vision, laser scanning, inertial sensing and intermittant GPS to estimate the motion of the rotorcraft, detect the river without a prior map, and create a 3D map of the riverine environment. Our hardware and software approach is cognizant of the need to perform multi-kilometer missions below tree level with size, weight and power constraints. We present experimental results along a 2 km loop of river using a surrogate perception payload. Overall we can build an S. Scherer ( ) · S. Achar · H. Cover · A. Chambers · S. Nuske · S. Singh Robotics Institute, Carnegie Mellon University, 5000 Forbes Ave, Pittsburgh, PA 15213, USA e-mail: [email protected] S. Achar e-mail: [email protected] H. Cover e-mail: [email protected] A. Chambers e-mail: [email protected] S. Nuske e-mail: [email protected] S. Singh e-mail: [email protected] J. Rehder Institute of Control Systems, Hamburg University of Technology, Eissendorfer Strasse 40, 21073 Hamburg, Germany e-mail: [email protected] accurate 3D obstacle map and a 2D map of the river course and width from light onboard sensing.