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Bearing-Based Distributed Control and Estimation of Multi-Agent Systems  [PDF]
Shiyu Zhao,Daniel Zelazo
Computer Science , 2015,
Abstract: This paper studies the distributed control and estimation of multi-agent systems based on bearing information. In particular, we consider two problems: (i) the distributed control of bearing-constrained formations using relative position measurements and (ii) the distributed localization of sensor networks using bearing measurements. Both of the two problems are considered in arbitrary dimensional spaces. The analyses of the two problems rely on the recently developed bearing rigidity theory. We show that the two problems have the same mathematical formulation and can be solved by identical protocols. The proposed controller and estimator can globally solve the two problems without ambiguity. The results are supported with illustrative simulations.
Location,Localization,and Localizability
Location, Localization, and Localizability

Yunhao Liu Member,ACM,Senior Member,IEEE Zheng Yang Student Member,IEEE Xiaoping Wang Student Member,IEEE Lirong Jian Student Member,IEEE,

计算机科学技术学报 , 2010,
Abstract: Location-aware technology spawns numerous unforeseen pervasive applications in a wide range of living,production, commence,and public services.This article provides an overview of the location,localization,and localizability issues of wireless ad-hoc and sensor networks.Making data geographically meaningful,location information is essential for many applications,and it deeply aids a number of network functions,such as network routing,topology control,coverage, boundary detection,clustering,etc.We investigat...
Bearing Rigidity and Almost Global Bearing-Only Formation Stabilization  [PDF]
Shiyu Zhao,Daniel Zelazo
Computer Science , 2014,
Abstract: A fundamental problem that the bearing rigidity theory studies is to determine when a framework can be uniquely determined up to a translation and a scaling factor by its inter-neighbor bearings. While many previous works focused on the bearing rigidity of two-dimensional frameworks, a first contribution of this paper is to extend these results to arbitrary dimensions. It is shown that a framework in an arbitrary dimension can be uniquely determined up to a translation and a scaling factor by the bearings if and only if the framework is infinitesimally bearing rigid. In this paper, the proposed bearing rigidity theory is further applied to the bearing-only formation stabilization problem where the target formation is defined by inter-neighbor bearings and the feedback control uses only bearing measurements. Nonlinear distributed bearing-only formation control laws are proposed for the cases with and without a global orientation. It is proved that the control laws can almost globally stabilize infinitesimally bearing rigid formations. Numerical simulations are provided to support the analysis.
Concurrent Initialization for Bearing-Only SLAM  [PDF]
Rodrigo Munguía,Antoni Grau
Sensors , 2010, DOI: 10.3390/s100301511
Abstract: Simultaneous Localization and Mapping (SLAM) is perhaps the most fundamental problem to solve in robotics in order to build truly autonomous mobile robots. The sensors have a large impact on the algorithm used for SLAM. Early SLAM approaches focused on the use of range sensors as sonar rings or lasers. However, cameras have become more and more used, because they yield a lot of information and are well adapted for embedded systems: they are light, cheap and power saving. Unlike range sensors which provide range and angular information, a camera is a projective sensor which measures the bearing of images features. Therefore depth information (range) cannot be obtained in a single step. This fact has propitiated the emergence of a new family of SLAM algorithms: the Bearing-Only SLAM methods, which mainly rely in especial techniques for features system-initialization in order to enable the use of bearing sensors (as cameras) in SLAM systems. In this work a novel and robust method, called Concurrent Initialization, is presented which is inspired by having the complementary advantages of the Undelayed and Delayed methods that represent the most common approaches for addressing the problem. The key is to use concurrently two kinds of feature representations for both undelayed and delayed stages of the estimation. The simulations results show that the proposed method surpasses the performance of previous schemes.
Bearing-Only SLAM: Stochastic Triangulation Method  [PDF]
Munguía-Alcalá Rodrigo Francisco,Grau-Saldes Antoni
Ingeniería, investigación y tecnología , 2013,
Abstract: El SLAM (simultaneous localization and mapping) es una técnica en la cual un robot o vehículo autónomo opera en un entorno a priori desconocido, utilizando únicamente sus sensores de abordo, mientras construye un mapa de su entorno, el cual utiliza al mismo tiempo para localizarse. Los sensores tienen un gran impacto en los algoritmos usados en SLAM. Enfoques recientes se están centrando en el uso de cámaras como sensor principal, ya que generan mucha información y están bien adaptadas para su aplicación en sistemas embebidos: son ligeras, baratas y ahorran energía. Sin embargo, a diferencia de los sensores de rango, los cuales proveen información angular y de rango, una cámara es un sensor proyectivo que mide el ángulo(bearing) respecto a los elementos de la imagen, por lo que la profundidad o rango no puede ser obtenida mediante una sola medición. Lo anterior ha motivado la aparición de una nueva familia de métodos en SLAM: los métodos de SLAM basados en sensores angulares, los cuales están principalmente basados en técnicas especiales para la inicialización de características en el sistema, permitiendo el uso de sensores angulares (como cámaras) en SLAM. Este artículo presenta un método práctico para la inicialización de nuevas características en sistemas de SLAM basados en sensores angulares. El método propuesto implementa mediante un retardo una técnica de triangulación estocástica para definir una hipótesis para la profundidad inicial de las características. Para mostrar el desempe o del método propuesto se presentan resultados experimentales con simulaciones y también se presentan dos casos de aplicación para escenarios con datos reales procedentes de distintos sensores angulares.
Teleportation Protocols Requiring Only One Classical Bit  [PDF]
Subhash Kak
Physics , 2003,
Abstract: The standard protocol for teleportation of a quantum state requires an entangled pair of particles and the use of two classical bits of information. Here, we present two protocols for teleportation that require only one classical bit. In the first protocol, chained XOR operations are performed on the particles before one of them is removed to the remote location where the state is being teleported. In the second protocol, three entangled particles are used.
Cooperative localization in wireless ad hoc and sensor networks using hybrid distance and bearing (angle of arrival) measurements  [cached]
Eren Tolga
EURASIP Journal on Wireless Communications and Networking , 2011,
Abstract: This article provides the graphical properties which can ensure unique localizability in cooperative networks with hybrid distance and bearing (angle of arrival) measurements. Furthermore, within the networks satisfying these graphical properties, this article identifies further sets of conditions so that the associated computational complexity becomes linear in the number of sensor nodes. We show how, by forming a spanning tree used once for distances and a second time for bearings where the underlying graph is connected, the localization problem can be made solvable in linear time with significantly less number of sensing links and smaller sensing radii of nodes compared with the cooperative networks with distance-only or bearing-only measurements. These easily localizable networks can be localized in polynomial time when measurements are noisy.
Localizability in de Sitter space  [PDF]
N. Yokomizo,J. C. A. Barata
Physics , 2010, DOI: 10.1088/1751-8113/45/36/365401
Abstract: An analogue of the Newton-Wigner position operator is defined for a massive neutral scalar field in de Sitter space. The one-particle subspace of the theory, consisting of positive-energy solutions of the Klein-Gordon equation selected by the Hadamard condition, is identified with an irreducible representation of de Sitter group. Postulates of localizability analogous to those written by Wightman for fields in Minkowski space are formulated on it, and a unique solution is shown to exist. A simple expression for the time-evolution of the operator is presented.
Localizability of Wireless Sensor Networks: Beyond Wheel Extension  [PDF]
Buddhadeb Sau,Krishnendu Mukhopadhyaya
Computer Science , 2013,
Abstract: A network is called localizable if the positions of all the nodes of the network can be computed uniquely. If a network is localizable and embedded in plane with generic configuration, the positions of the nodes may be computed uniquely in finite time. Therefore, identifying localizable networks is an important function. If the complete information about the network is available at a single place, localizability can be tested in polynomial time. In a distributed environment, networks with trilateration orderings (popular in real applications) and wheel extensions (a specific class of localizable networks) embedded in plane can be identified by existing techniques. We propose a distributed technique which efficiently identifies a larger class of localizable networks. This class covers both trilateration and wheel extensions. In reality, exact distance is almost impossible or costly. The proposed algorithm based only on connectivity information. It requires no distance information.
Track Processing Approach for Bearing-Only Target Tracking
Hui Chen,Chen Li
International Journal of Intelligent Systems and Applications , 2009,
Abstract: This paper mainly studies angle-measurement based track processing approach to overcome the existing problems in the applications of traditional approaches for bearing-only target locating and tracking system. First, this paper gives suited data association algorithms including track initiation and point-track association. Moreover, a new tracking filtering association gate method is presented through analysis of the target motion characteristics in polar coordinates for improving bearing-only measurement confirming efficiency of real target and limiting false track overextension with the dense clutter. Then, by analyzing the feasibility of using multi-model technology, the IMM is adopt as filtering algorithm to solve existing problem in bearing-only tracking for complicated target motion in two dimensional angle plane. As the results, the two dimensional bearing-only tracking accuracy of real target is improved and false tracking is greatly limited. Moreover, computation cost of IMM is analyzed in view of the real-time demand of bearing-only tracking. Finally, this paper gives some concrete summary of multi-model choosing principle. The application of the proposed approach in a simulation system proves its effectiveness and practicability.
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