Obstacle

About: Obstacle is a research topic. Over the lifetime, 9517 publications have been published within this topic receiving 94760 citations. The topic is also known as: impediment & barrier.

Using obstacle analysis to identify contingency requirements on an unpiloted aerial vehicle

Abstract: This paper describes the use of Obstacle Analysis to identify anomaly handling requirements for a safety-critical, autonomous system. The software requirements for the system evolved during operations due to an on-going effort to increase the autonomous system’s robustness. The resulting increase in autonomy also increased system complexity. This investigation used Obstacle Analysis to identify and to reason incrementally about new requirements for handling failures and other anomalous events. Results reported in the paper show that Obstacle Analysis complemented standard safety-analysis techniques in identifying undesirable behaviors and ways to resolve them. The step-by-step use of Obstacle Analysis identified potential side effects and missing monitoring and control requirements. Adding an Availability Indicator and feature-interaction patterns proved useful for the analysis of obstacle resolutions. The paper discusses the consequences of these results in terms of the adoption of Obstacle Analysis to analyze anomaly handling requirements in evolving systems.

Optimizing and Post Processing of a Smart Beamformer for Obstacle Retrieval

Abstract: Beamforming is one of the most interesting techniques used to know distance systems in order to detect punctual, widespread obstacles. If correctly associated to DOA (Difference of Arrival), it can allow the description of obstacle shape. Distance ranging, for mobile and fixed systems, namely cars, vehicles, vessels and airplanes, that is a key issue for demands of nowadays. Distance between cars and from obstacles can be established and measured using laser and ultrasound. Cloudy and foggy conditions are very important requirements for testing distance ranging facilities. If based on acoustic waves, they can be easily integrated by sophisticated on-board software in order to perform new features. This research presents interesting aspects of defining new requirements for an acoustic scanning capable of reconstructing fixed obstacle features by targeting them using a special array of sensors. The term “acoustic scanning” is intended here as an aspect of sound ranging and reproduction regarding spatial locations of the obstacle, that is spatial shaping. The paper illustrates first an experimental system from which it is possible to derive parameters for setting spatial shaping of scenarios and after a clear identification of DOAs.

Motion Planning in Dynamic Environments

Abstract: Motion planning in dynamic environments is made possible using the concept of velocity obstacles. It maps the colliding velocities of the robot with any moving or static obstacle to the robot’s velocity space. Collision avoidance is achieved by selecting the robot velocity outside the velocity obstacles. This concept was first proposed in [3] for the linear case of obstacles moving on straight line trajectories, and is extended here to obstacles moving along arbitrary trajectories. The non-linear velocity obstacle (NLVO) takes into account the shape, velocity and path curvature of the moving obstacle. It allows to select a single avoidance maneuver (if one exists) that avoids any number of obstacles that move on any known trajectories. The nonlinear v-obstacle can be generated as a time integral of the colliding velocities, or by computing its boundaries using analytic expressions.

Inverse obstacle scattering with limited-aperture data

Abstract: Inverse obstacle scattering aims to extract information about distant and unknown targets using wave propagation. This study concentrates on a two-dimensional setting using time-harmonic acoustic plane waves as incident fields and taking the obstacles to be sound-hard with smooth or polygonal boundary. Measurement data is simulated by sending one incident wave towards the area of interest and computing the far field pattern (1) on the whole circle of observation directions, (2) only in directions close to backscattering, and (3) only in directions close to forward-scattering. A variant of the enclosure method is introduced, based on applying the far field operator to an explicitly constructed density, yielding information about the convex hull of the obstacle. The numerical evidence presented suggests that the convex hull of obstacles can be approximately recovered from noisy limited-aperture far field data.