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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.


Papers
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Journal ArticleDOI
TL;DR: Novel algorithms that enable the existing location-based routing protocols that resist obstacles are proposed that create low overhead and significantly reduce the average route length, and, therefore, improve the energy consumption and end-to-end delay for a wireless sensor network with obstacles.
Abstract: In wireless sensor networks, a geographic region without the functionality of sensing and communication can generally be treated as an obstacle, which significantly impacts the performance of existing location-based routing. An obstacle can dynamically be formed due to unbalanced deployment, sensor failure, or power exhaustion, animus interference, or physical obstacles such as mountains or buildings. This paper proposes novel algorithms that enable the existing location-based routing protocols that resist obstacles. Applying the proposed active route-guiding protocol for single obstacles (S-RGP), border nodes that surround the obstacles will actively establish a forbidden region for concave obstacles and make the obstacle information transparent. Then, packets will be guided to overcome the obstacle and move along the shorter path from the encountered border node to the sink node. In addition, the proposed active route-guiding protocol for multiple obstacles (M-RGP) takes multiple obstacles into consideration and integrates their information to help the packets overcome multiple obstacles. Simulation results show that the proposed S-RGP and M-RGP create low overhead and significantly reduce the average route length, and, therefore, improve the energy consumption and end-to-end delay for a wireless sensor network with obstacles.

31 citations

Journal ArticleDOI
TL;DR: A method to combine a low-cost 16 beam solid state laser sensor and a conventional video camera for obstacle detection is presented and results show that the method accurately detects the presence of obstacles and the direction of their movement.
Abstract: In this paper, a method to combine a low-cost 16 beam solid state laser sensor and a conventional video camera for obstacle detection is presented. The system is intended to form a non-intrusive virtual barrier at both sides of an intelligent wheelchair, in order to protect the user in everyday outdoor and indoor environments, like office, home, or pedestrian areas. In this type of environments, the shape of the obstacles is very heterogeneous (for instance, having a variable width along their height), so their detection via the conventional sensors installed in the wheelchair presents difficulties, especially in the most exposed areas of the user that are the sides of their torso. With the proposed system, when an obstacle intersects a beam, the intersection point is projected in the associated image and optical flow is calculated at both sides of this point. Using the optical flow, several classifiers have been trained and tested in order to automatically discern between intersections produced by the user and those produced by external obstacles. Results show that the method accurately detects the presence of obstacles and the direction of their movement.

31 citations

Patent
24 Aug 2016
TL;DR: In this article, a multi-sensor fusion-based autonomous obstacle avoidance unmanned aerial vehicle system and a control method are presented, which includes an environment information real-time detection module, obstacle data analysis processing module and obstacle avoidance decision-making module.
Abstract: The invention discloses a multi-sensor fusion-based autonomous obstacle avoidance unmanned aerial vehicle system and a control method. The system includes an environment information real-time detection module which carries out real-time detection on surrounding environment through adopting a multi-sensor fusion technology and transmits detected information to an obstacle data analysis processing module, the obstacle data analysis processing module which carries out environment structure sensing construction on the received information of the surrounding environment so as to determine an obstacle, and an obstacle avoidance decision-making module which determines an obstacle avoidance decision according to the output result of the obstacle data analysis processing module, so as to achieve obstacle avoidance of an unmanned aerial vehicle through the driving of power modules which is performed by a flight control system. According to the multi-sensor fusion-based autonomous obstacle avoidance unmanned aerial vehicle system and the control method of the invention, binocular machine vision systems are arranged around the body of the unmanned aerial vehicle, so that 3D space reconstruction can be realized; and an ultrasonic device and a millimeter wave radar in an advancing direction are used in cooperation, so that an obstacle avoidance method is more comprehensive. The system has the advantages of high real-time performance of obstacle detection, long visual detection distance and high resolution.

31 citations

Journal ArticleDOI
TL;DR: A novel system called CrowdWatch is proposed, which leverages mobile crowd sensing and crowd intelligence aggregation to detect temporary obstacles and make effective alerts for distracted walkers.
Abstract: Pedestrians distracted by smartphones are easy to meet with various dangers when crossing or walking on the street, such as the obstacles on the sidewalk (e.g., temporary parking and road repairing). Existing works about pedestrian safety are mostly based on the sensing capabilities from a single device. The surrounding information that can be learned, however, is quite limited or incomplete. Therefore, in many cases the dangers cannot be detected and the pedestrians cannot be alerted. In this paper, a novel system called CrowdWatch is proposed, which leverages mobile crowd sensing and crowd intelligence aggregation to detect temporary obstacles and make effective alerts for distracted walkers. To detect obstacles, we first study the regular rules of pedestrians’ avoidance behaviors from the aspects of turn-making and visual contexts. The Dempster–Shafer evidence theory is then used to fuse the behavior and visual contexts, and further calculate the confidence of obstacle existence. Afterwards, we leverage the features of pedestrians’ traces to characterize an appropriate dangerous area, which is used to alert distracted walkers. The conducted experiments with 36 participants and different obstacle settings indicate that the crowd-intelligence-based obstacle detection method is effective and the accuracy of reminding attains 83.3%.

31 citations

Journal ArticleDOI
TL;DR: In this article, the authors propose a three-dimensional extension of the velocity obstacle method that can reactively generate an avoidance maneuver by changing the vehicle velocity vector based on the encounter geometry.
Abstract: This paper proposes a novel avoidance method called the three-dimensional velocity obstacle method. The method is designed for unmanned aerial vehicle applications, in particular to autonomously handle uncoordinated multiple encounters in an integrated airspace, by exploiting the limited space in a three-dimensional manner. The method is a three-dimensional extension of the velocity obstacle method that can reactively generate an avoidance maneuver by changing the vehicle velocity vector based on the encounter geometry. Adverse maneuvers of the obstacle are anticipated by introducing the concept of a buffer velocity set, which ensures that the ownship will diverge with sufficient space in case of sudden imminence. A three-dimensional resolution is generated by choosing the right plane for avoidance, in which the unmanned aerial vehicle conducts a pure turning maneuver. Implementation of the three-dimensional velocity obstacle method is tested in several simulations that demonstrate its capability to resol...

31 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20241
20231,483
20223,389
2021407
2020817
2019873