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Editorial

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138 KiB

Open AccessEditorial

Sensors in Collaboration Increase Individual Potentialities

by Gonzalo Pajares

Sensors 2012, 12(4), 4892-4896; https://doi.org/10.3390/s120404892 - 13 Apr 2012

Cited by 3 | Viewed by 6333

Abstract

Different applications require different sensor technologies and methods to achieve specific goals. Particular sensor designs are focused on solving problems. It is well-known that individual sensors can be limited when complex problems or applications are involved or the application requires sensing in different [...] Read more.

Different applications require different sensor technologies and methods to achieve specific goals. Particular sensor designs are focused on solving problems. It is well-known that individual sensors can be limited when complex problems or applications are involved or the application requires sensing in different locations or even different geographical areas. [...] Full article

(This article belongs to the Special Issue Collaborative Sensors)

Research

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5802 KiB

Open AccessArticle

Improvement of Kinect_TM Sensor Capabilities by Fusion with Laser Sensing Data Using Octree

by Alfredo Chávez and Henrik Karstoft

Sensors 2012, 12(4), 3868-3878; https://doi.org/10.3390/s120403868 - 26 Mar 2012

Cited by 7 | Viewed by 7710

Abstract

To enhance sensor capabilities, sensor data readings from different modalities must be fused. The main contribution of this paper is to present a sensor data fusion approach that can reduce Kinect_TM sensor limitations. This approach involves combining laser with Kinect_TM sensors. [...] Read more.

To enhance sensor capabilities, sensor data readings from different modalities must be fused. The main contribution of this paper is to present a sensor data fusion approach that can reduce Kinect_TM sensor limitations. This approach involves combining laser with Kinect_TM sensors. Sensor data is modelled in a 3D environment based on octrees using a probabilistic occupancy estimation. The Bayesian method, which takes into account the uncertainty inherent in the sensor measurements, is used to fuse the sensor information and update the 3D octree map. The sensor fusion yields a significant increase of the field of view of the Kinect_TM sensor that can be used for robot tasks. Full article

(This article belongs to the Special Issue Collaborative Sensors)

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473 KiB

Open AccessArticle

Consolidation of a WSN and Minimax Method to Rapidly Neutralise Intruders in Strategic Installations

by Jesus Conesa-Muñoz and Angela Ribeiro

Sensors 2012, 12(3), 3281-3301; https://doi.org/10.3390/s120303281 - 7 Mar 2012

Cited by 3 | Viewed by 7196

Abstract

Due to the sensitive international situation caused by still-recent terrorist attacks, there is a common need to protect the safety of large spaces such as government buildings, airports and power stations. To address this problem, developments in several research fields, such as video [...] Read more.

Due to the sensitive international situation caused by still-recent terrorist attacks, there is a common need to protect the safety of large spaces such as government buildings, airports and power stations. To address this problem, developments in several research fields, such as video and cognitive audio, decision support systems, human interface, computer architecture, communications networks and communications security, should be integrated with the goal of achieving advanced security systems capable of checking all of the specified requirements and spanning the gap that presently exists in the current market. This paper describes the implementation of a decision system for crisis management in infrastructural building security. Specifically, it describes the implementation of a decision system in the management of building intrusions. The positions of the unidentified persons are reported with the help of a Wireless Sensor Network (WSN). The goal is to achieve an intelligent system capable of making the best decision in real time in order to quickly neutralise one or more intruders who threaten strategic installations. It is assumed that the intruders’ behaviour is inferred through sequences of sensors’ activations and their fusion. This article presents a general approach to selecting the optimum operation from the available neutralisation strategies based on a Minimax algorithm. The distances among different scenario elements will be used to measure the risk of the scene, so a path planning technique will be integrated in order to attain a good performance. Different actions to be executed over the elements of the scene such as moving a guard, blocking a door or turning on an alarm will be used to neutralise the crisis. This set of actions executed to stop the crisis is known as the neutralisation strategy. Finally, the system has been tested in simulations of real situations, and the results have been evaluated according to the final state of the intruders. In 86.5% of the cases, the system achieved the capture of the intruders, and in 59.25% of the cases, they were intercepted before they reached their objective. Full article

(This article belongs to the Special Issue Collaborative Sensors)

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477 KiB

Open AccessArticle

Artificial Neural Network for Location Estimation in Wireless Communication Systems

by Chien-Sheng Chen

Sensors 2012, 12(3), 2798-2817; https://doi.org/10.3390/s120302798 - 1 Mar 2012

Cited by 36 | Viewed by 7964

Abstract

In a wireless communication system, wireless location is the technique used to estimate the location of a mobile station (MS). To enhance the accuracy of MS location prediction, we propose a novel algorithm that utilizes time of arrival (TOA) measurements and the angle [...] Read more.

In a wireless communication system, wireless location is the technique used to estimate the location of a mobile station (MS). To enhance the accuracy of MS location prediction, we propose a novel algorithm that utilizes time of arrival (TOA) measurements and the angle of arrival (AOA) information to locate MS when three base stations (BSs) are available. Artificial neural networks (ANN) are widely used techniques in various areas to overcome the problem of exclusive and nonlinear relationships. When the MS is heard by only three BSs, the proposed algorithm utilizes the intersections of three TOA circles (and the AOA line), based on various neural networks, to estimate the MS location in non-line-of-sight (NLOS) environments. Simulations were conducted to evaluate the performance of the algorithm for different NLOS error distributions. The numerical analysis and simulation results show that the proposed algorithms can obtain more precise location estimation under different NLOS environments. Full article

(This article belongs to the Special Issue Collaborative Sensors)

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2883 KiB

Open AccessArticle

A Radar-Enabled Collaborative Sensor Network Integrating COTS Technology for Surveillance and Tracking

by Robert Kozma, Lan Wang, Khan Iftekharuddin, Ernest McCracken, Muhammad Khan, Khandakar Islam, Sushil R. Bhurtel and R. Murat Demirer

Sensors 2012, 12(2), 1336-1351; https://doi.org/10.3390/s120201336 - 31 Jan 2012

Cited by 12 | Viewed by 9479

Abstract

The feasibility of using Commercial Off-The-Shelf (COTS) sensor nodes is studied in a distributed network, aiming at dynamic surveillance and tracking of ground targets. Data acquisition by low-cost ( [...] Read more.

The feasibility of using Commercial Off-The-Shelf (COTS) sensor nodes is studied in a distributed network, aiming at dynamic surveillance and tracking of ground targets. Data acquisition by low-cost ( < $50 US) miniature low-power radar through a wireless mote is described. We demonstrate the detection, ranging and velocity estimation, classification and tracking capabilities of the mini-radar, and compare results to simulations and manual measurements. Furthermore, we supplement the radar output with other sensor modalities, such as acoustic and vibration sensors. This method provides innovative solutions for detecting, identifying, and tracking vehicles and dismounts over a wide area in noisy conditions. This study presents a step towards distributed intelligent decision support and demonstrates effectiveness of small cheap sensors, which can complement advanced technologies in certain real-life scenarios. Full article

(This article belongs to the Special Issue Collaborative Sensors)

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Open AccessArticle

A Low-Complexity Geometric Bilateration Method for Localization in Wireless Sensor Networks and Its Comparison with Least-Squares Methods

by Juan Cota-Ruiz, Jose-Gerardo Rosiles, Ernesto Sifuentes and Pablo Rivas-Perea

Sensors 2012, 12(1), 839-862; https://doi.org/10.3390/s120100839 - 12 Jan 2012

Cited by 36 | Viewed by 11939

Abstract

This research presents a distributed and formula-based bilateration algorithm that can be used to provide initial set of locations. In this scheme each node uses distance estimates to anchors to solve a set of circle-circle intersection (CCI) problems, solved through a purely geometric [...] Read more.

This research presents a distributed and formula-based bilateration algorithm that can be used to provide initial set of locations. In this scheme each node uses distance estimates to anchors to solve a set of circle-circle intersection (CCI) problems, solved through a purely geometric formulation. The resulting CCIs are processed to pick those that cluster together and then take the average to produce an initial node location. The algorithm is compared in terms of accuracy and computational complexity with a Least-Squares localization algorithm, based on the Levenberg–Marquardt methodology. Results in accuracy vs. computational performance show that the bilateration algorithm is competitive compared with well known optimized localization algorithms. Full article

(This article belongs to the Special Issue Collaborative Sensors)

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630 KiB

Open AccessArticle

Fusion of a Variable Baseline System and a Range Finder

by Javier Hernández-Aceituno, Leopoldo Acosta and Rafael Arnay

Sensors 2012, 12(1), 278-296; https://doi.org/10.3390/s120100278 - 28 Dec 2011

Cited by 4 | Viewed by 7397

Abstract

One of the greatest difficulties in stereo vision is the appearance of ambiguities when matching similar points from different images. In this article we analyze the effectiveness of using a fusion of multiple baselines and a range finder from a theoretical point of [...] Read more.

One of the greatest difficulties in stereo vision is the appearance of ambiguities when matching similar points from different images. In this article we analyze the effectiveness of using a fusion of multiple baselines and a range finder from a theoretical point of view, focusing on the results of using both prismatic and rotational articulations for baseline generation, and offer a practical case to prove its efficiency on an autonomous vehicle. Full article

(This article belongs to the Special Issue Collaborative Sensors)

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780 KiB

Open AccessArticle

Force to Rebalance Control of HRG and Suppression of Its Errors on the Basis of FPGA

by Xu Wang, Wenqi Wu, Bing Luo, Zhen Fang, Yun Li and Qingan Jiang

Sensors 2011, 11(12), 11761-11773; https://doi.org/10.3390/s111211761 - 16 Dec 2011

Cited by 41 | Viewed by 10586

Abstract

A novel design of force to rebalance control for a hemispherical resonator gyro (HRG) based on FPGA is demonstrated in this paper. The proposed design takes advantage of the automatic gain control loop and phase lock loop configuration in the drive mode while [...] Read more.

A novel design of force to rebalance control for a hemispherical resonator gyro (HRG) based on FPGA is demonstrated in this paper. The proposed design takes advantage of the automatic gain control loop and phase lock loop configuration in the drive mode while making full use of the quadrature control loop and rebalance control loop in controlling the oscillating dynamics in the sense mode. First, the math model of HRG with inhomogeneous damping and frequency split is theoretically analyzed. In addition, the major drift mechanisms in the HRG are described and the methods that can suppress the gyro drift are mentioned. Based on the math model and drift mechanisms suppression method, four control loops are employed to realize the manipulation of the HRG by using a FPGA circuit. The reference-phase loop and amplitude control loop are used to maintain the vibration of primary mode at its natural frequency with constant amplitude. The frequency split is readily eliminated by the quadrature loop with a DC voltage feedback from the quadrature component of the node. The secondary mode response to the angle rate input is nullified by the rebalance control loop. In order to validate the effect of the digital control of HRG, experiments are carried out with a turntable. The experimental results show that the design is suitable for the control of HRG which has good linearity scale factor and bias stability. Full article

(This article belongs to the Special Issue Collaborative Sensors)

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Open AccessArticle

ATLAS: A Traffic Load Aware Sensor MAC Design for Collaborative Body Area Sensor Networks

by Md. Obaidur Rahman, Choong Seon Hong, Sungwon Lee and Young-Cheol Bang

Sensors 2011, 11(12), 11560-11580; https://doi.org/10.3390/s111211560 - 12 Dec 2011

Cited by 42 | Viewed by 9509

Abstract

In collaborative body sensor networks, namely wireless body area networks(WBANs), each of the physical sensor applications is used to collaboratively monitor thehealth status of the human body. The applications of WBANs comprise diverse and dynamictraffic loads such as very low-rate periodic monitoring ( [...] Read more.

In collaborative body sensor networks, namely wireless body area networks(WBANs), each of the physical sensor applications is used to collaboratively monitor thehealth status of the human body. The applications of WBANs comprise diverse and dynamictraffic loads such as very low-rate periodic monitoring (i.e., observation) data and high-ratetraffic including event-triggered bursts. Therefore, in designing a medium access control(MAC) protocol for WBANs, energy conservation should be the primary concern duringlow-traffic periods, whereas a balance between satisfying high-throughput demand andefficient energy usage is necessary during high-traffic times. In this paper, we design atraffic load-aware innovative MAC solution for WBANs, called ATLAS. The design exploitsthe superframe structure of the IEEE 802.15.4 standard, and it adaptively uses the contentionaccess period (CAP), contention free period (CFP) and inactive period (IP) of the superframebased on estimated traffic load, by applying a dynamic “wh” (whenever which is required)approach. Unlike earlier work, the proposed MAC design includes load estimation fornetwork load-status awareness and a multi-hop communication pattern in order to preventenergy loss associated with long range transmission. Finally, ATLAS is evaluated throughextensive simulations in ns-2 and the results demonstrate the effectiveness of the protocol. Full article

(This article belongs to the Special Issue Collaborative Sensors)

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Open AccessArticle

Heterogeneous Collaborative Sensor Network for Electrical Management of an Automated House with PV Energy

by Manuel Castillo-Cagigal, Eduardo Matallanas, Álvaro Gutiérrez, Félix Monasterio-Huelin, Estefaná Caamaño-Martín, Daniel Masa-Bote and Javier Jiménez-Leube

Sensors 2011, 11(12), 11544-11559; https://doi.org/10.3390/s111211544 - 9 Dec 2011

Cited by 10 | Viewed by 9432

Abstract

In this paper we present a heterogeneous collaborative sensor network for electrical management in the residential sector. Improving demand-side management is very important in distributed energy generation applications. Sensing and control are the foundations of the “Smart Grid” which is the future of [...] Read more.

In this paper we present a heterogeneous collaborative sensor network for electrical management in the residential sector. Improving demand-side management is very important in distributed energy generation applications. Sensing and control are the foundations of the “Smart Grid” which is the future of large-scale energy management. The system presented in this paper has been developed on a self-sufficient solar house called “MagicBox” equipped with grid connection, PV generation, lead-acid batteries, controllable appliances and smart metering. Therefore, there is a large number of energy variables to be monitored that allow us to precisely manage the energy performance of the house by means of collaborative sensors. The experimental results, performed on a real house, demonstrate the feasibility of the proposed collaborative system to reduce the consumption of electrical power and to increase energy efficiency. Full article

(This article belongs to the Special Issue Collaborative Sensors)

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Open AccessArticle

An Integrated Testbed for Cooperative Perception with Heterogeneous Mobile and Static Sensors

by Adrián Jiménez-González, José Ramiro Martínez-de Dios and Aníbal Ollero

Sensors 2011, 11(12), 11516-11543; https://doi.org/10.3390/s111211516 - 9 Dec 2011

Cited by 45 | Viewed by 10407

Abstract

Cooperation among devices with different sensing, computing and communication capabilities provides interesting possibilities in a growing number of problems and applications including domotics (domestic robotics), environmental monitoring or intelligent cities, among others. Despite the increasing interest in academic and industrial communities, experimental tools [...] Read more.

Cooperation among devices with different sensing, computing and communication capabilities provides interesting possibilities in a growing number of problems and applications including domotics (domestic robotics), environmental monitoring or intelligent cities, among others. Despite the increasing interest in academic and industrial communities, experimental tools for evaluation and comparison of cooperative algorithms for such heterogeneous technologies are still very scarce. This paper presents a remote testbed with mobile robots and Wireless Sensor Networks (WSN) equipped with a set of low-cost off-the-shelf sensors, commonly used in cooperative perception research and applications, that present high degree of heterogeneity in their technology, sensed magnitudes, features, output bandwidth, interfaces and power consumption, among others. Its open and modular architecture allows tight integration and interoperability between mobile robots and WSN through a bidirectional protocol that enables full interaction. Moreover, the integration of standard tools and interfaces increases usability, allowing an easy extension to new hardware and software components and the reuse of code. Different levels of decentralization are considered, supporting from totally distributed to centralized approaches. Developed for the EU-funded Cooperating Objects Network of Excellence (CONET) and currently available at the School of Engineering of Seville (Spain), the testbed provides full remote control through the Internet. Numerous experiments have been performed, some of which are described in the paper. Full article

(This article belongs to the Special Issue Collaborative Sensors)

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Open AccessArticle

Development of a 3D Parallel Mechanism Robot Arm with Three Vertical-Axial Pneumatic Actuators Combined with a Stereo Vision System

by Mao-Hsiung Chiang and Hao-Ting Lin

Sensors 2011, 11(12), 11476-11494; https://doi.org/10.3390/s111211476 - 5 Dec 2011

Cited by 21 | Viewed by 10342

Abstract

This study aimed to develop a novel 3D parallel mechanism robot driven by three vertical-axial pneumatic actuators with a stereo vision system for path tracking control. The mechanical system and the control system are the primary novel parts for developing a 3D parallel [...] Read more.

This study aimed to develop a novel 3D parallel mechanism robot driven by three vertical-axial pneumatic actuators with a stereo vision system for path tracking control. The mechanical system and the control system are the primary novel parts for developing a 3D parallel mechanism robot. In the mechanical system, a 3D parallel mechanism robot contains three serial chains, a fixed base, a movable platform and a pneumatic servo system. The parallel mechanism are designed and analyzed first for realizing a 3D motion in the X-Y-Z coordinate system of the robot’s end-effector. The inverse kinematics and the forward kinematics of the parallel mechanism robot are investigated by using the Denavit-Hartenberg notation (D-H notation) coordinate system. The pneumatic actuators in the three vertical motion axes are modeled. In the control system, the Fourier series-based adaptive sliding-mode controller with H_∞ tracking performance is used to design the path tracking controllers of the three vertical servo pneumatic actuators for realizing 3D path tracking control of the end-effector. Three optical linear scales are used to measure the position of the three pneumatic actuators. The 3D position of the end-effector is then calculated from the measuring position of the three pneumatic actuators by means of the kinematics. However, the calculated 3D position of the end-effector cannot consider the manufacturing and assembly tolerance of the joints and the parallel mechanism so that errors between the actual position and the calculated 3D position of the end-effector exist. In order to improve this situation, sensor collaboration is developed in this paper. A stereo vision system is used to collaborate with the three position sensors of the pneumatic actuators. The stereo vision system combining two CCD serves to measure the actual 3D position of the end-effector and calibrate the error between the actual and the calculated 3D position of the end-effector. Furthermore, to verify the feasibility of the proposed parallel mechanism robot driven by three vertical pneumatic servo actuators, a full-scale test rig of the proposed parallel mechanism pneumatic robot is set up. Thus, simulations and experiments for different complex 3D motion profiles of the robot end-effector can be successfully achieved. The desired, the actual and the calculated 3D position of the end-effector can be compared in the complex 3D motion control. Full article

(This article belongs to the Special Issue Collaborative Sensors)

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Open AccessArticle

Improving Social Odometry Robot Networks with Distributed Reputation Systems for Collaborative Purposes

by David Fraga, Álvaro Gutiérrez, Juan Carlos Vallejo, Alexandre Campo and Zorana Bankovic

Sensors 2011, 11(12), 11372-11389; https://doi.org/10.3390/s111211372 - 30 Nov 2011

Cited by 6 | Viewed by 7689

Abstract

The improvement of odometry systems in collaborative robotics remains an important challenge for several applications. Social odometry is a social technique which confers the robots the possibility to learn from the others. This paper analyzes social odometry and proposes and follows a methodology [...] Read more.

The improvement of odometry systems in collaborative robotics remains an important challenge for several applications. Social odometry is a social technique which confers the robots the possibility to learn from the others. This paper analyzes social odometry and proposes and follows a methodology to improve its behavior based on cooperative reputation systems. We also provide a reference implementation that allows us to compare the performance of the proposed solution in highly dynamic environments with the performance of standard social odometry techniques. Simulation results quantitatively show the benefits of this collaborative approach that allows us to achieve better performances than social odometry. Full article

(This article belongs to the Special Issue Collaborative Sensors)

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Open AccessArticle

The New Pelagic Operational Observatory of the Catalan Sea (OOCS) for the Multisensor Coordinated Measurement of Atmospheric and Oceanographic Conditions

by Nixon Bahamon, Jacopo Aguzzi, Raffaele Bernardello, Miguel-Angel Ahumada-Sempoal, Joan Puigdefabregas, Jordi Cateura, Eduardo Muñoz, Zoila Velásquez and Antonio Cruzado

Sensors 2011, 11(12), 11251-11272; https://doi.org/10.3390/s111211251 - 28 Nov 2011

Cited by 23 | Viewed by 12346

Abstract

The new pelagic Operational Observatory of the Catalan Sea (OOCS) for the coordinated multisensor measurement of atmospheric and oceanographic conditions has been recently installed (2009) in the Catalan Sea (41°39'N, 2°54'E; Western Mediterranean) and continuously operated (with minor maintenance gaps) until today. This [...] Read more.

The new pelagic Operational Observatory of the Catalan Sea (OOCS) for the coordinated multisensor measurement of atmospheric and oceanographic conditions has been recently installed (2009) in the Catalan Sea (41°39'N, 2°54'E; Western Mediterranean) and continuously operated (with minor maintenance gaps) until today. This multiparametric platform is moored at 192 m depth, 9.3 km off Blanes harbour (Girona, Spain). It is composed of a buoy holding atmospheric sensors and a set of oceanographic sensors measuring the water conditions over the upper 100 m depth. The station is located close to the head of the Blanes submarine canyon where an important multispecies pelagic and demersal fishery gives the station ecological and economic relevance. The OOCS provides important records on atmospheric and oceanographic conditions, the latter through the measurement of hydrological and biogeochemical parameters, at depths with a time resolution never attained before for this area of the Mediterranean. Twenty four moored sensors and probes operating in a coordinated fashion provide important data on Essential Ocean Variables (EOVs; UNESCO) such as temperature, salinity, pressure, dissolved oxygen, chlorophyll fluorescence, and turbidity. In comparison with other pelagic observatories presently operating in other world areas, OOCS also measures photosynthetic available radiation (PAR) from above the sea surface and at different depths in the upper 50 m. Data are recorded each 30 min and transmitted in real-time to a ground station via GPRS. This time series is published and automatically updated at the frequency of data collection on the official OOCS website (http://www.ceab.csic.es/~oceans). Under development are embedded automated routines for the in situ data treatment and assimilation into numerical models, in order to provide a reliable local marine processing forecast. In this work, our goal is to detail the OOCS multisensor architecture in relation to the coordinated capability for the remote, continuous and prolonged monitoring of atmospheric and oceanographic conditions, including data communication and storage. Accordingly, time series of measurements for a number of biological parameters will be presented for the summer months of 2011. Marine hindcast outputs from the numerical models implemented for simulating the conditions over the study area are shown. The strong changes of atmospheric conditions recorded in the last years over the area have altered the marine conditions of living organisms, but the dimension of the impact remains unclear. The OOCS multisensor coordinated monitoring has been specifically designed to address this issue, thus contributing to better understand the present environmental fluctuations and to provide a sound basis for a more accurate marine forecast system. Full article

(This article belongs to the Special Issue Collaborative Sensors)

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378 KiB

Open AccessArticle

Distributed Bees Algorithm Parameters Optimization for a Cost Efficient Target Allocation in Swarms of Robots

by Aleksandar Jevtić and Álvaro Gutiérrez

Sensors 2011, 11(11), 10880-10893; https://doi.org/10.3390/s111110880 - 21 Nov 2011

Cited by 13 | Viewed by 7634

Abstract

Swarms of robots can use their sensing abilities to explore unknown environments and deploy on sites of interest. In this task, a large number of robots is more effective than a single unit because of their ability to quickly cover the area. However, [...] Read more.

Swarms of robots can use their sensing abilities to explore unknown environments and deploy on sites of interest. In this task, a large number of robots is more effective than a single unit because of their ability to quickly cover the area. However, the coordination of large teams of robots is not an easy problem, especially when the resources for the deployment are limited. In this paper, the Distributed Bees Algorithm (DBA), previously proposed by the authors, is optimized and applied to distributed target allocation in swarms of robots. Improved target allocation in terms of deployment cost efficiency is achieved through optimization of the DBA’s control parameters by means of a Genetic Algorithm. Experimental results show that with the optimized set of parameters, the deployment cost measured as the average distance traveled by the robots is reduced. The cost-efficient deployment is in some cases achieved at the expense of increased robots’ distribution error. Nevertheless, the proposed approach allows the swarm to adapt to the operating conditions when available resources are scarce. Full article

(This article belongs to the Special Issue Collaborative Sensors)

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Open AccessArticle

Angular Rate Estimation Using a Distributed Set of Accelerometers

by Sungsu Park and Sung Kyung Hong

Sensors 2011, 11(11), 10444-10457; https://doi.org/10.3390/s111110444 - 2 Nov 2011

Cited by 24 | Viewed by 7776

Abstract

A distributed set of accelerometers based on the minimum number of 12 accelerometers allows for computation of the magnitude of angular rate without using the integration operation. However, it is not easy to extract the magnitude of angular rate in the presence of [...] Read more.

A distributed set of accelerometers based on the minimum number of 12 accelerometers allows for computation of the magnitude of angular rate without using the integration operation. However, it is not easy to extract the magnitude of angular rate in the presence of the accelerometer noises, and even worse, it is difficult to determine the direction of a rotation because the angular rate is present in its quadratic form within the inertial measurement system equations. In this paper, an extended Kalman filter scheme to correctly estimate both the direction and magnitude of the angular rate through fusion of the angular acceleration and quadratic form of the angular rate is proposed. We also provide observability analysis for the general distributed accelerometers-based inertial measurement unit, and show that the angular rate can be correctly estimated by general nonlinear state estimators such as an extended Kalman filter, except under certain extreme conditions. Full article

(This article belongs to the Special Issue Collaborative Sensors)

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Open AccessArticle

A Grid-Based Distributed Event Detection Scheme for Wireless Sensor Networks

by Ja Won Ko and Yoon-Hwa Choi

Sensors 2011, 11(11), 10048-10062; https://doi.org/10.3390/s111110048 - 25 Oct 2011

Cited by 9 | Viewed by 6861

Abstract

This paper presents a grid-based distributed event detection scheme for wireless sensor networks. The network is divided into square-shaped grids of predefined grid size, where sensor nodes in each grid form a cluster with a cluster head. Event detection at each grid alone [...] Read more.

This paper presents a grid-based distributed event detection scheme for wireless sensor networks. The network is divided into square-shaped grids of predefined grid size, where sensor nodes in each grid form a cluster with a cluster head. Event detection at each grid alone based on the readings of its member nodes is limited in event detection performance, especially for a small event region compared to the grid size. To improve the performance, each grid is further divided into 2 × 2 sub-grids of equal size. The decision on an event is made by finding a square region of 2 × 2 sub-grids, not necessarily in the same grid, that passed a predefined threshold. This process is conducted at each cluster head in a distributed manner by inter-cluster communications. Event detection is initiated when a cluster head receives an alarm from its member nodes. The cluster-head communicates with its neighboring cluster heads to exchange the number of nodes reporting an alarm. The threshold for event detection can be dynamically adjusted to reflect the number of sensor nodes in a grid and event size, if known. High event detection accuracy is achieved with a relatively low threshold without sacrificing false alarm rate by filtering most errors due to transient faults and isolating nodes with permanent faults. Experimental results show that the proposed scheme can achieve high detection accuracy, while maintaining low false alarm rate. Full article

(This article belongs to the Special Issue Collaborative Sensors)

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Open AccessArticle

Improving Prediction Accuracy for WSN Data Reduction by Applying Multivariate Spatio-Temporal Correlation

by Carlos Carvalho, Danielo G. Gomes, Nazim Agoulmine and José Neuman De Souza

Sensors 2011, 11(11), 10010-10037; https://doi.org/10.3390/s111110010 - 25 Oct 2011

Cited by 52 | Viewed by 9076

Abstract

This paper proposes a method based on multivariate spatial and temporal correlation to improve prediction accuracy in data reduction for Wireless Sensor Networks (WSN). Prediction of data not sent to the sink node is a technique used to save energy in WSNs by [...] Read more.

This paper proposes a method based on multivariate spatial and temporal correlation to improve prediction accuracy in data reduction for Wireless Sensor Networks (WSN). Prediction of data not sent to the sink node is a technique used to save energy in WSNs by reducing the amount of data traffic. However, it may not be very accurate. Simulations were made involving simple linear regression and multiple linear regression functions to assess the performance of the proposed method. The results show a higher correlation between gathered inputs when compared to time, which is an independent variable widely used for prediction and forecasting. Prediction accuracy is lower when simple linear regression is used, whereas multiple linear regression is the most accurate one. In addition to that, our proposal outperforms some current solutions by about 50% in humidity prediction and 21% in light prediction. To the best of our knowledge, we believe that we are probably the first to address prediction based on multivariate correlation for WSN data reduction. Full article

(This article belongs to the Special Issue Collaborative Sensors)

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Open AccessArticle

Collaborative Localization Algorithms for Wireless Sensor Networks with Reduced Localization Error

by Prasan Kumar Sahoo and I-Shyan Hwang

Sensors 2011, 11(10), 9989-10009; https://doi.org/10.3390/s111009989 - 21 Oct 2011

Cited by 32 | Viewed by 8740

Abstract

Localization is an important research issue in Wireless Sensor Networks (WSNs). Though Global Positioning System (GPS) can be used to locate the position of the sensors, unfortunately it is limited to outdoor applications and is costly and power consuming. In order to find [...] Read more.

Localization is an important research issue in Wireless Sensor Networks (WSNs). Though Global Positioning System (GPS) can be used to locate the position of the sensors, unfortunately it is limited to outdoor applications and is costly and power consuming. In order to find location of sensor nodes without help of GPS, collaboration among nodes is highly essential so that localization can be accomplished efficiently. In this paper, novel localization algorithms are proposed to find out possible location information of the normal nodes in a collaborative manner for an outdoor environment with help of few beacons and anchor nodes. In our localization scheme, at most three beacon nodes should be collaborated to find out the accurate location information of any normal node. Besides, analytical methods are designed to calculate and reduce the localization error using probability distribution function. Performance evaluation of our algorithm shows that there is a trade off betweendeployed number of beacon nodes and localization error, and average localization time of the network can be increased with increase in the number of normal nodes deployed over a region. Full article

(This article belongs to the Special Issue Collaborative Sensors)

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Open AccessArticle

A Multi-Sensorial Hybrid Control for Robotic Manipulation in Human-Robot Workspaces

by Jorge Pomares, Ivan Perea, Gabriel J. García, Carlos A. Jara, Juan A. Corrales and Fernando Torres

Sensors 2011, 11(10), 9839-9862; https://doi.org/10.3390/s111009839 - 20 Oct 2011

Cited by 10 | Viewed by 10534

Abstract

Autonomous manipulation in semi-structured environments where human operators can interact is an increasingly common task in robotic applications. This paper describes an intelligent multi-sensorial approach that solves this issue by providing a multi-robotic platform with a high degree of autonomy and the capability [...] Read more.

Autonomous manipulation in semi-structured environments where human operators can interact is an increasingly common task in robotic applications. This paper describes an intelligent multi-sensorial approach that solves this issue by providing a multi-robotic platform with a high degree of autonomy and the capability to perform complex tasks. The proposed sensorial system is composed of a hybrid visual servo control to efficiently guide the robot towards the object to be manipulated, an inertial motion capture system and an indoor localization system to avoid possible collisions between human operators and robots working in the same workspace, and a tactile sensor algorithm to correctly manipulate the object. The proposed controller employs the whole multi-sensorial system and combines the measurements of each one of the used sensors during two different phases considered in the robot task: a first phase where the robot approaches the object to be grasped, and a second phase of manipulation of the object. In both phases, the unexpected presence of humans is taken into account. This paper also presents the successful results obtained in several experimental setups which verify the validity of the proposed approach. Full article

(This article belongs to the Special Issue Collaborative Sensors)

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714 KiB

Open AccessArticle

Odometry and Laser Scanner Fusion Based on a Discrete Extended Kalman Filter for Robotic Platooning Guidance

by Felipe Espinosa, Carlos Santos, Marta Marrón-Romera, Daniel Pizarro, Fernando Valdés and Javier Dongil

Sensors 2011, 11(9), 8339-8357; https://doi.org/10.3390/s110908339 - 29 Aug 2011

Cited by 32 | Viewed by 12187

Abstract

This paper describes a relative localization system used to achieve the navigation of a convoy of robotic units in indoor environments. This positioning system is carried out fusing two sensorial sources: (a) an odometric system and (b) a laser scanner together with artificial [...] Read more.

This paper describes a relative localization system used to achieve the navigation of a convoy of robotic units in indoor environments. This positioning system is carried out fusing two sensorial sources: (a) an odometric system and (b) a laser scanner together with artificial landmarks located on top of the units. The laser source allows one to compensate the cumulative error inherent to dead-reckoning; whereas the odometry source provides less pose uncertainty in short trajectories. A discrete Extended Kalman Filter, customized for this application, is used in order to accomplish this aim under real time constraints. Different experimental results with a convoy of Pioneer P3-DX units tracking non-linear trajectories are shown. The paper shows that a simple setup based on low cost laser range systems and robot built-in odometry sensors is able to give a high degree of robustness and accuracy to the relative localization problem of convoy units for indoor applications. Full article

(This article belongs to the Special Issue Collaborative Sensors)

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2075 KiB

Open AccessArticle

Common Criteria Related Security Design Patterns for Intelligent Sensors—Knowledge Engineering-Based Implementation

by Andrzej Bialas

Sensors 2011, 11(8), 8085-8114; https://doi.org/10.3390/s110808085 - 17 Aug 2011

Cited by 15 | Viewed by 8289

Abstract

Intelligent sensors experience security problems very similar to those inherent to other kinds of IT products or systems. The assurance for these products or systems creation methodologies, like Common Criteria (ISO/IEC 15408) can be used to improve the robustness of the sensor systems [...] Read more.

Intelligent sensors experience security problems very similar to those inherent to other kinds of IT products or systems. The assurance for these products or systems creation methodologies, like Common Criteria (ISO/IEC 15408) can be used to improve the robustness of the sensor systems in high risk environments. The paper presents the background and results of the previous research on patterns-based security specifications and introduces a new ontological approach. The elaborated ontology and knowledge base were validated on the IT security development process dealing with the sensor example. The contribution of the paper concerns the application of the knowledge engineering methodology to the previously developed Common Criteria compliant and pattern-based method for intelligent sensor security development. The issue presented in the paper has a broader significance in terms that it can solve information security problems in many application domains. Full article

(This article belongs to the Special Issue Collaborative Sensors)

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1925 KiB

Open AccessArticle

Smart Pipes—Instrumented Water Pipes, Can This Be Made a Reality?

by Nicole Metje, David N. Chapman, David Cheneler, Michael Ward and Andrew M. Thomas

Sensors 2011, 11(8), 7455-7475; https://doi.org/10.3390/s110807455 - 27 Jul 2011

Cited by 30 | Viewed by 13442

Abstract

Several millions of kilometres of pipes and cables are buried beneath our streets in the UK. As they are not visible and easily accessible, the monitoring of their integrity as well as the quality of their contents is a challenge. Any information of [...] Read more.

Several millions of kilometres of pipes and cables are buried beneath our streets in the UK. As they are not visible and easily accessible, the monitoring of their integrity as well as the quality of their contents is a challenge. Any information of these properties aids the utility owners in their planning and management of their maintenance regime. Traditionally, expensive and very localised sensors are used to provide irregular measurements of these properties. In order to have a complete picture of the utility network, cheaper sensors need to be investigated which would allow large numbers of small sensors to be incorporated into (or near to) the pipe leading to so-called smart pipes. This paper focuses on a novel trial where a short section of a prototype smart pipe was buried using mainly off-the-shelf sensors and communication elements. The challenges of such a burial are presented together with the limitations of the sensor system. Results from the sensors were obtained during and after burial indicating that off-the-shelf sensors can be used in a smart pipes system although further refinements are necessary in order to miniaturise these sensors. The key challenges identified were the powering of these sensors and the communication of the data to the operator using a range of different methods. Full article

(This article belongs to the Special Issue Collaborative Sensors)

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961 KiB

Open AccessArticle

Data Fusion Algorithms for Multiple Inertial Measurement Units

by Jared B. Bancroft and Gérard Lachapelle

Sensors 2011, 11(7), 6771-6798; https://doi.org/10.3390/s110706771 - 29 Jun 2011

Cited by 105 | Viewed by 15821

Abstract

A single low cost inertial measurement unit (IMU) is often used in conjunction with GPS to increase the accuracy and improve the availability of the navigation solution for a pedestrian navigation system. This paper develops several fusion algorithms for using multiple IMUs to [...] Read more.

A single low cost inertial measurement unit (IMU) is often used in conjunction with GPS to increase the accuracy and improve the availability of the navigation solution for a pedestrian navigation system. This paper develops several fusion algorithms for using multiple IMUs to enhance performance. In particular, this research seeks to understand the benefits and detriments of each fusion method in the context of pedestrian navigation. Three fusion methods are proposed. First, all raw IMU measurements are mapped onto a common frame (i.e., a virtual frame) and processed in a typical combined GPS-IMU Kalman filter. Second, a large stacked filter is constructed of several IMUs. This filter construction allows for relative information between the IMUs to be used as updates. Third, a federated filter is used to process each IMU as a local filter. The output of each local filter is shared with a master filter, which in turn, shares information back with the local filters. The construction of each filter is discussed and improvements are made to the virtual IMU (VIMU) architecture, which is the most commonly used architecture in the literature. Since accuracy and availability are the most important characteristics of a pedestrian navigation system, the analysis of each filter’s performance focuses on these two parameters. Data was collected in two environments, one where GPS signals are moderately attenuated and another where signals are severely attenuated. Accuracy is shown as a function of architecture and the number of IMUs used. Full article

(This article belongs to the Special Issue Collaborative Sensors)

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1448 KiB

Open AccessArticle

Collaborative Processing of Wearable and Ambient Sensor System for Blood Pressure Monitoring

by Masayuki Nakamura, Jiro Nakamura, Guillaume Lopez, Masaki Shuzo and Ichiro Yamada

Sensors 2011, 11(7), 6760-6770; https://doi.org/10.3390/s110706760 - 28 Jun 2011

Cited by 23 | Viewed by 10100

Abstract

This paper describes wireless wearable and ambient sensors that cooperate to monitor a person’s vital signs such as heart rate and blood pressure during daily activities. Each wearable sensor is attached on different parts of the body. The wearable sensors require a high [...] Read more.

This paper describes wireless wearable and ambient sensors that cooperate to monitor a person’s vital signs such as heart rate and blood pressure during daily activities. Each wearable sensor is attached on different parts of the body. The wearable sensors require a high sampling rate and time synchronization to provide a precise analysis of the received signals. The trigger signal for synchronization is provided by the ambient sensors, which detect the user’s presence. The Bluetooth and IEEE 802.15.4 wireless technologies are used for real-time sensing and time synchronization. Thus, this wearable health-monitoring sensor response is closely related to the context in which it is being used. Experimental results indicate that the system simultaneously provides information about the user’s location and vital signs, and the synchronized wearable sensors successfully measures vital signs with a 1 ms resolution. Full article

(This article belongs to the Special Issue Collaborative Sensors)

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583 KiB

Open AccessArticle

Trust Index Based Fault Tolerant Multiple Event Localization Algorithm for WSNs

by Xianghua Xu, Xueyong Gao, Jian Wan and Naixue Xiong

Sensors 2011, 11(7), 6555-6574; https://doi.org/10.3390/s110706555 - 27 Jun 2011

Cited by 35 | Viewed by 8680

Abstract

This paper investigates the use of wireless sensor networks for multiple event source localization using binary information from the sensor nodes. The events could continually emit signals whose strength is attenuated inversely proportional to the distance from the source. In this context, faults [...] Read more.

This paper investigates the use of wireless sensor networks for multiple event source localization using binary information from the sensor nodes. The events could continually emit signals whose strength is attenuated inversely proportional to the distance from the source. In this context, faults occur due to various reasons and are manifested when a node reports a wrong decision. In order to reduce the impact of node faults on the accuracy of multiple event localization, we introduce a trust index model to evaluate the fidelity of information which the nodes report and use in the event detection process, and propose the Trust Index based Subtract on Negative Add on Positive (TISNAP) localization algorithm, which reduces the impact of faulty nodes on the event localization by decreasing their trust index, to improve the accuracy of event localization and performance of fault tolerance for multiple event source localization. The algorithm includes three phases: first, the sink identifies the cluster nodes to determine the number of events occurred in the entire region by analyzing the binary data reported by all nodes; then, it constructs the likelihood matrix related to the cluster nodes and estimates the location of all events according to the alarmed status and trust index of the nodes around the cluster nodes. Finally, the sink updates the trust index of all nodes according to the fidelity of their information in the previous reporting cycle. The algorithm improves the accuracy of localization and performance of fault tolerance in multiple event source localization. The experiment results show that when the probability of node fault is close to 50%, the algorithm can still accurately determine the number of the events and have better accuracy of localization compared with other algorithms. Full article

(This article belongs to the Special Issue Collaborative Sensors)

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504 KiB

Open AccessArticle

Diffusion-Based EM Algorithm for Distributed Estimation of Gaussian Mixtures in Wireless Sensor Networks

by Yang Weng, Wendong Xiao and Lihua Xie

Sensors 2011, 11(6), 6297-6316; https://doi.org/10.3390/s110606297 - 14 Jun 2011

Cited by 33 | Viewed by 8837

Abstract

Distributed estimation of Gaussian mixtures has many applications in wireless sensor network (WSN), and its energy-efficient solution is still challenging. This paper presents a novel diffusion-based EM algorithm for this problem. A diffusion strategy is introduced for acquiring the global statistics in EM [...] Read more.

Distributed estimation of Gaussian mixtures has many applications in wireless sensor network (WSN), and its energy-efficient solution is still challenging. This paper presents a novel diffusion-based EM algorithm for this problem. A diffusion strategy is introduced for acquiring the global statistics in EM algorithm in which each sensor node only needs to communicate its local statistics to its neighboring nodes at each iteration. This improves the existing consensus-based distributed EM algorithm which may need much more communication overhead for consensus, especially in large scale networks. The robustness and scalability of the proposed approach can be achieved by distributed processing in the networks. In addition, we show that the proposed approach can be considered as a stochastic approximation method to find the maximum likelihood estimation for Gaussian mixtures. Simulation results show the efficiency of this approach. Full article

(This article belongs to the Special Issue Collaborative Sensors)

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1125 KiB

Open AccessArticle

A QoS-Guaranteed Coverage Precedence Routing Algorithm for Wireless Sensor Networks

by Joe-Air Jiang, Tzu-Shiang Lin, Cheng-Long Chuang, Chia-Pang Chen, Chin-Hong Sun, Jehn-Yih Juang, Jiun-Chuan Lin and Wei-Wen Liang

Sensors 2011, 11(4), 3418-3438; https://doi.org/10.3390/s110403418 - 24 Mar 2011

Cited by 22 | Viewed by 11651

Abstract

For mission-critical applications of wireless sensor networks (WSNs) involving extensive battlefield surveillance, medical healthcare, etc., it is crucial to have low-power, new protocols, methodologies and structures for transferring data and information in a network with full sensing coverage capability for an extended [...] Read more.

For mission-critical applications of wireless sensor networks (WSNs) involving extensive battlefield surveillance, medical healthcare, etc., it is crucial to have low-power, new protocols, methodologies and structures for transferring data and information in a network with full sensing coverage capability for an extended working period. The upmost mission is to ensure that the network is fully functional providing reliable transmission of the sensed data without the risk of data loss. WSNs have been applied to various types of mission-critical applications. Coverage preservation is one of the most essential functions to guarantee quality of service (QoS) in WSNs. However, a tradeoff exists between sensing coverage and network lifetime due to the limited energy supplies of sensor nodes. In this study, we propose a routing protocol to accommodate both energy-balance and coverage-preservation for sensor nodes in WSNs. The energy consumption for radio transmissions and the residual energy over the network are taken into account when the proposed protocol determines an energy-efficient route for a packet. The simulation results demonstrate that the proposed protocol is able to increase the duration of the on-duty network and provide up to 98.3% and 85.7% of extra service time with 100% sensing coverage ratio comparing with LEACH and the LEACH-Coverage-U protocols, respectively. Full article

(This article belongs to the Special Issue Collaborative Sensors)

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Review

Jump to: Editorial, Research

1186 KiB

Open AccessReview

Brain Computer Interfaces, a Review

by Luis Fernando Nicolas-Alonso and Jaime Gomez-Gil

Sensors 2012, 12(2), 1211-1279; https://doi.org/10.3390/s120201211 - 31 Jan 2012

Cited by 1605 | Viewed by 71084

Abstract

A brain-computer interface (BCI) is a hardware and software communications system that permits cerebral activity alone to control computers or external devices. The immediate goal of BCI research is to provide communications capabilities to severely disabled people who are totally paralyzed or ‘locked [...] Read more.

A brain-computer interface (BCI) is a hardware and software communications system that permits cerebral activity alone to control computers or external devices. The immediate goal of BCI research is to provide communications capabilities to severely disabled people who are totally paralyzed or ‘locked in’ by neurological neuromuscular disorders, such as amyotrophic lateral sclerosis, brain stem stroke, or spinal cord injury. Here, we review the state-of-the-art of BCIs, looking at the different steps that form a standard BCI: signal acquisition, preprocessing or signal enhancement, feature extraction, classification and the control interface. We discuss their advantages, drawbacks, and latest advances, and we survey the numerous technologies reported in the scientific literature to design each step of a BCI. First, the review examines the neuroimaging modalities used in the signal acquisition step, each of which monitors a different functional brain activity such as electrical, magnetic or metabolic activity. Second, the review discusses different electrophysiological control signals that determine user intentions, which can be detected in brain activity. Third, the review includes some techniques used in the signal enhancement step to deal with the artifacts in the control signals and improve the performance. Fourth, the review studies some mathematic algorithms used in the feature extraction and classification steps which translate the information in the control signals into commands that operate a computer or other device. Finally, the review provides an overview of various BCI applications that control a range of devices. Full article

(This article belongs to the Special Issue Collaborative Sensors)

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1270 KiB

Open AccessReview

A Comprehensive Approach to WSN-Based ITS Applications: A Survey

by Fernando Losilla, Antonio-Javier Garcia-Sanchez, Felipe Garcia-Sanchez, Joan Garcia-Haro and Zygmunt J. Haas

Sensors 2011, 11(11), 10220-10265; https://doi.org/10.3390/s111110220 - 28 Oct 2011

Cited by 97 | Viewed by 14362

Abstract

In order to perform sensing tasks, most current Intelligent Transportation Systems (ITS) rely on expensive sensors, which offer only limited functionality. A more recent trend consists of using Wireless Sensor Networks (WSN) for such purpose, which reduces the required investment and enables the [...] Read more.

In order to perform sensing tasks, most current Intelligent Transportation Systems (ITS) rely on expensive sensors, which offer only limited functionality. A more recent trend consists of using Wireless Sensor Networks (WSN) for such purpose, which reduces the required investment and enables the development of new collaborative and intelligent applications that further contribute to improve both driving safety and traffic efficiency. This paper surveys the application of WSNs to such ITS scenarios, tackling the main issues that may arise when developing these systems. The paper is divided into sections which address different matters including vehicle detection and classification as well as the selection of appropriate communication protocols, network architecture, topology and some important design parameters. In addition, in line with the multiplicity of different technologies that take part in ITS, it does not consider WSNs just as stand-alone systems, but also as key components of heterogeneous systems cooperating along with other technologies employed in vehicular scenarios. Full article

(This article belongs to the Special Issue Collaborative Sensors)

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