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.

LIDAR Obstacle Warning and Avoidance System for Unmanned Aircraft

Abstract: The availability of powerful eye-safe laser sources and the recent advancements in electro-optical and mechanical beam-steering components have allowed laser-based Light Detection and Ranging (LIDAR) to become a promising technology for obstacle warning and avoidance in a variety of manned and unmanned aircraft applications. LIDAR outstanding angular resolution and accuracy characteristics are coupled to its good detection performance in a wide range of incidence angles and weather conditions, providing an ideal obstacle avoidance solution, which is especially attractive in low-level flying platforms such as helicopters and small-to-medium size Unmanned Aircraft (UA). The Laser Obstacle Avoidance Marconi (LOAM) system is one of such systems, which was jointly developed and tested by SELEX-ES and the Italian Air Force Research and Flight Test Centre. The system was originally conceived for military rotorcraft platforms and, in this paper, we briefly review the previous work and discuss in more details some of the key development activities required for integration of LOAM on UA platforms. The main hardware and software design features of this LOAM variant are presented, including a brief description of the system interfaces and sensor characteristics, together with the system performance models and data processing algorithms for obstacle detection, classification and avoidance. In particular, the paper focuses on the algorithm proposed for optimal avoidance trajectory generation in UA applications.

Stepping back to see the big picture: when obstacles elicit global processing

Abstract: Can obstacles prompt people to look at the "big picture" and open up their minds? Do the cognitive effects of obstacles extend beyond the tasks with which they interfere? These questions were addressed in 6 studies involving both physical and nonphysical obstacles and different measures of global versus local processing styles. Perceptual scope increased after participants solved anagrams in the presence, rather than the absence, of an auditory obstacle (random words played in the background; Study 1), particularly among individuals low in volatility (i.e., those who are inclined to stay engaged and finish what they do; Study 4). It also increased immediately after participants encountered a physical obstacle while navigating a maze (Study 3A) and when compared with doing nothing (Study 3B). Conceptual scope increased after participants solved anagrams while hearing random numbers framed as an "obstacle to overcome" rather than a "distraction to ignore" (Study 2) and after participants navigated a maze with a physical obstacle, compared with a maze without a physical obstacle, but only when trait (Study 5) or state (Study 6) volatility was low. Results suggest that obstacles trigger an "if obstacle, then start global processing" response, primarily when people are inclined to stay engaged and finish ongoing activities. Implications for dealing with life's obstacles and related research are discussed.

User-driven active guidance system

Abstract: A user-driven, active guidance system for guiding visually impaired users through obstacle filled routes of travel. The system includes an obstacle detection system, having an array of ultrasonic sensors, which detects the distance to and location of obstacles and a controller for receiving obstacle data and determining an optimal path around the obstacle so as to return the user back to the original path of travel without losing orientation or direction. The system provides active guidance by exerting physical force upon the user to intuitively direct the user around the obstacle. The system is driven by the user's motion and comprises a cane, as well as the my of ultrasonic sensors and controller supported on a pair of guide wheels.

Visual recognition of obstacles on roads

Abstract: As part of a driver support system for motor vehicles on freeways, an obstacle recognition system was developed within the EUREKA project PROMETHEUS over the last four years. The obstacle recognition system uses a single monochrome TV camera and a multi-processor robot vision system. The recognition system includes a road tracker and an obstacle detector that were described elsewhere, and an object classification and tracking module presented here. The module is based on generic 2D object models. It recognizes obstacles in real time and from distances of 200 to 300 m, sufficient for high-speed driving. The module was extensively tested in real-world scenes on the German Autobahn and on various other roads, including city streets with dense traffic. >

Multi-UAV path planning in obstacle rich environments using Rapidly-exploring Random Trees

Abstract: This paper presents path planning algorithms using Rapidly-exploring Random Trees (RRTs) to generate paths for multiple unmanned air vehicles (UAVs) in real time, from given starting locations to goal locations in the presence of static, pop-up and dynamic obstacles. Generating non-conflicting paths in obstacle rich environments for a group of UAVs within a given short time window is a challenging task. The difficulty further increases because the turn radius constraints of the UAVs have to be comparable with the corridors where they intend to fly. Hence we first generate a path quickly using RRT by taking the kinematic constraints of the UAVs into account. Then in order to generate a low cost path we develop an anytime algorithm that yields paths whose quality improves as flight proceeds. When the UAV detects a dynamic obstacle, the path planner avoids it based on a set of criteria. In order to track generated paths, a guidance law based on pursuit and line-of-sight is developed. Simulation studies are carried out to show the performance of the proposed algorithm.