http://research.engr.oregonstate.edu/immiscibles/sites/research.engr.oregonstate.edu.immiscibles/files/Papers/Wildenschild_Sheppard_AWR_2012.pdf

X-ray imaging and analysis techniques for quantifying pore-scale structure and processes in subsurface porous medium systems

We review a range of techniques related to navigation of unmanned vehicles through unknown environments with obstacles, especially those that rigorously ensure collision avoidance (given certain assumptions about the system). This topic continues to be an active area of research, and we highlight some directions in which available approaches may be improved. The paper discusses models of the sensors and vehicle kinematics, assumptions about the environment, and performance criteria. Methods applicable to stationary obstacles, moving obstacles and multiple vehicles scenarios are all reviewed. In preference to global approaches based on full knowledge of the environment, particular attention is given to reactive methods based on local sensory data, with a special focus on recently proposed navigation laws based on model predictive and sliding mode control.

/pdf/algorithms-for-collision-free-navigation-of-mobile-robots-in-1s1ksc76if.pdf

Algorithms for collision-free navigation of mobile robots in complex cluttered environments: a survey

This book offers the definitive guide to the theory and practice of disaster robotics. It can serve as an introduction for researchers and technologists, a reference for emergency managers, and a textbook in field robotics. Written by a pioneering researcher in the field who has herself participated in fifteen deployments of robots in disaster response and recovery, the book covers theory and practice, the history of the field, and specific missions. After a broad overview of rescue robotics in the context of emergency informatics, the book provides a chronological summary and formal analysis of the thirty-four documented deployments of robots to disasters that include the 2001 collapse of the World Trade Center, Hurricane Katrina, the 2010 Haiti earthquake, the Deepwater Horizon oil spill, the 2011 Japanese earthquake and tsunami, and numerous mining accidents. It then examines disaster robotics in the typical robot modalities of ground, air, and marine, addressing such topics as robot types, missions and tasks, and selection heuristics for each modality. Finally, the book discusses types of fieldwork, providing practical advice on matters that include collecting data and collaborating with emergency professionals. The field of disaster robotics has lacked a comprehensive overview. This book by a leader in the field, offering a unique combination of the theoretical and the practical, fills the gap.

Disaster Robotics

An efficient and analytical continuous-curvature path-smoothing algorithm, which fits an ordered sequence of waypoints generated by an obstacle-avoidance path planner, is proposed. The algorithm is based upon parametric cubic Bezier curves; thus, it is inherently closed-form in its expression, and the algorithm only requires the maximum curvature to be defined. The algorithm is, thus, computational efficient and easy to implement. Results show the effectiveness of the analytical algorithm in generating a continuous-curvature path, which satisfies an upper bound-curvature constraint, and that the path generated requires less control effort to track and minimizes control-input variability.

An Analytical Continuous-Curvature Path-Smoothing Algorithm

We present a new remeshing scheme based on the idea of improving mesh quality by a series of local modifications of the mesh geometry and connectivity. Our contribution to the family of local modification techniques is an area-based smoothing technique. Area-based smoothing allows the control of both triangle quality and vertex sampling over the mesh, as a function of some criteria, e.g. the mesh curvature. To perform local modifications of arbitrary genus meshes we use dynamic patch-wise parameterization. The parameterization is constructed and updated on-the-fly as the algorithm progresses with local updates. As a post-processing stage, we introduce a new algorithm to improve the regularity of the mesh connectivity. The algorithm is able to create an unstructured mesh with a very small number of irregular vertices. Our remeshing scheme is robust, runs at interactive speeds and can be applied to arbitrary complex meshes.

/pdf/explicit-surface-remeshing-1ktun8swm2.pdf

Explicit surface remeshing

Estimating intrinsic geometric properties of a surface from a polygonal mesh obtained from range data is an important stage of numerous algorithms in computer and robot vision, computer graphics, geometric modeling, industrial and biomedical engineering. This work considers different computational schemes for local estimation of intrinsic curvature geometric properties. Five different algorithms and their modifications were tested on triangular meshes that represent tessellations of synthetic geometric models. The results were compared with the analytically computed values of the Gaussian and mean curvatures of the non-uniform rational B-spline (NURBs) surfaces, these meshes originated from. This work manifests the best algorithms suited for that indeed different algorithms should be employed to compute the Gaussian and mean curvatures.

/pdf/a-comparison-of-gaussian-and-mean-curvatures-estimation-481foi5q1x.pdf

A comparison of Gaussian and mean curvatures estimation methods on triangular meshes

http://www.cs.technion.ac.il/~octavian/PUBLICATIONS/RangeImageCurvatures.pdf

A comparison of Gaussian and mean curvature estimation methods on triangular meshes of range image data

This paper offers a path planning algorithm based on splines. The sought path avoids the obstacles, and is smooth and short. Smoothing is used as an integral part of the algorithm, and not only as a final improvement to a path found by other methods. In order to avoid a very difficult optimization over all the path's points, it is modeled by a sequence of splines defined by a gradually increasing number of knots.

/pdf/spline-based-robot-navigation-1hvtxtm0jq.pdf

Spline-Based Robot Navigation

This paper presents a comparison of four most recent ROS-based monocular SLAM-related methods: ORB-SLAM, REMODE, LSD-SLAM, and DPPTAM, and analyzes their feasibility for a mobile robot application in indoor environment. We tested these methods using video data that was recorded from a conventional wide-angle full HD webcam with a rolling shutter. The camera was mounted on a human-operated prototype of an unmanned ground vehicle, which followed a closed-loop trajectory. Both feature-based methods (ORB-SLAM, REMODE) and direct SLAMrelated algorithms (LSD-SLAM, DPPTAM) demonstrated reasonably good results in detection of volumetric objects, corners, obstacles and other local features. However, we met difficulties with recovering typical for offices homogeneously colored walls, since all of these methods created empty spaces in a reconstructed sparse 3D scene. This may cause collisions of an autonomously guided robot with unfeatured walls and thus limits applicability of maps, which are obtained by the considered monocular SLAM-related methods for indoor robot navigation.

Comparative analysis of ROS-based monocular SLAM methods for indoor navigation

Bug algorithms are a class of popular algorithms for autonomous robot navigation in unknown environments with local information. Very natural, with low memory requirements, Bug strategies do not yet allow any competitive analysis. The bound on the robot's path changes from scene to scene depending on the obstacles, even though a new obstacle may not alter the length of the shortest path. We propose a new competitive algorithm, CautiousBug, whose competitive factor has an order of O(d/sup m-1/), where d is the length of the optimal path from starting point S to a target point T. m = 2/sup #Min-1/ and #Min denote the number of the distance function isolated local minima points in the given environment. Simulations were performed to study the average competitive factor of the algorithm.

/pdf/cautiousbug-a-competitive-algorithm-for-sensory-based-robot-18ywo3dxj2.pdf

Evgeni Magid

Papers

A comparison of Gaussian and mean curvatures estimation methods on triangular meshes

A comparison of Gaussian and mean curvature estimation methods on triangular meshes of range image data

Spline-Based Robot Navigation

Comparative analysis of ROS-based monocular SLAM methods for indoor navigation

CautiousBug: a competitive algorithm for sensory-based robot navigation