Localization in Unstructured Environments: Towards Autonomous Robots in Forests with Delaunay Triangulation

Autonomous harvesting and transportation is a long-term goal of the forest industry. One of the main challenges is the accurate localization of both vehicles and trees in a forest. Forests are unstructured environments where it is difficult to find a group of significant landmarks for current fast feature-based place recognition algorithms. This paper proposes a novel approach where local observations are matched to a general tree map using the Delaunay triangularization as the representation format. Instead of point cloud based matching methods, we utilize a topology-based method. First, tree trunk positions are registered at a prior run done by a forest harvester. Second, the resulting map is Delaunay triangularized. Third, a local submap of the autonomous robot is registered, triangularized and matched using triangular similarity maximization to estimate the position of the robot. We test our method on a dataset accumulated from a forestry site at Lieksa, Finland. A total length of 2100\,m of harvester path was recorded by an industrial harvester with a 3D laser scanner and a geolocation unit fixed to the frame. Our experiments show a 12\,cm s.t.d. in the location accuracy and with real-time data processing for speeds not exceeding 0.5\,m/s. The accuracy and speed limit is realistic during forest operations

How to teach a van to drive: an undergraduate perspective on the 2005 DARPA Grand Challenge

This paper describes how a team of undergraduate volunteers from California Institute of Technology (Caltech) developed a robotic vehicle that can navigate completely autonomously through the Mojave Desert. Called Alice, the vehicle was Caltech's entry to the 2005 DARPA Grand Challenge which aimed to generate the technology needed to build and program an unmanned ground vehicle through 130 miles of difficult terrain completely autonomously in under ten hours. Although Alice failed to win the competition, she did succeed in her original purpose of teaching a new generation of students about engineering, how to apply theory to the real world, how to debug and deal with shortcomings and schedules, and most importantly, how to work as a team on a complex problem