Sensors

518 KiB

Open AccessArticle

Analyzing Body Movements within the Laban Effort Framework Using a Single Accelerometer

by Basel Kikhia, Miguel Gomez, Lara Lorna Jiménez, Josef Hallberg, Niklas Karvonen and Kåre Synnes

Sensors 2014, 14(3), 5725-5741; https://doi.org/10.3390/s140305725 - 21 Mar 2014

Cited by 24 | Viewed by 9316

Abstract

This article presents a study on analyzing body movements by using a single accelerometer sensor. The investigated categories of body movements belong to the Laban Effort Framework: Strong—Light, Free—Bound and Sudden—Sustained. All body movements were represented by a set of activities used for [...] Read more.

This article presents a study on analyzing body movements by using a single accelerometer sensor. The investigated categories of body movements belong to the Laban Effort Framework: Strong—Light, Free—Bound and Sudden—Sustained. All body movements were represented by a set of activities used for data collection. The calculated accuracy of detecting the body movements was based on collecting data from a single wireless tri-axial accelerometer sensor. Ten healthy subjects collected data from three body locations (chest, wrist and thigh) simultaneously in order to analyze the locations comparatively. The data was then processed and analyzed using Machine Learning techniques. The wrist placement was found to be the best single location to record data for detecting Strong—Light body movements using the Random Forest classifier. The wrist placement was also the best location for classifying Bound—Free body movements using the SVM classifier. However, the data collected from the chest placement yielded the best results for detecting Sudden—Sustained body movements using the Random Forest classifier. The study shows that the choice of the accelerometer placement should depend on the targeted type of movement. In addition, the choice of the classifier when processing data should also depend on the chosen location and the target movement. Full article

(This article belongs to the Section Physical Sensors)

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2023 KiB

Open AccessArticle

Fully Distributed Monitoring Architecture Supporting Multiple Trackees and Trackers in Indoor Mobile Asset Management Application

by Seol Young Jeong, Hyeong Gon Jo and Soon Ju Kang

Sensors 2014, 14(3), 5702-5724; https://doi.org/10.3390/s140305702 - 21 Mar 2014

Cited by 18 | Viewed by 10377

Abstract

A tracking service like asset management is essential in a dynamic hospital environment consisting of numerous mobile assets (e.g., wheelchairs or infusion pumps) that are continuously relocated throughout a hospital. The tracking service is accomplished based on the key technologies of an indoor [...] Read more.

A tracking service like asset management is essential in a dynamic hospital environment consisting of numerous mobile assets (e.g., wheelchairs or infusion pumps) that are continuously relocated throughout a hospital. The tracking service is accomplished based on the key technologies of an indoor location-based service (LBS), such as locating and monitoring multiple mobile targets inside a building in real time. An indoor LBS such as a tracking service entails numerous resource lookups being requested concurrently and frequently from several locations, as well as a network infrastructure requiring support for high scalability in indoor environments. A traditional centralized architecture needs to maintain a geographic map of the entire building or complex in its central server, which can cause low scalability and traffic congestion. This paper presents a self-organizing and fully distributed indoor mobile asset management (MAM) platform, and proposes an architecture for multiple trackees (such as mobile assets) and trackers based on the proposed distributed platform in real time. In order to verify the suggested platform, scalability performance according to increases in the number of concurrent lookups was evaluated in a real test bed. Tracking latency and traffic load ratio in the proposed tracking architecture was also evaluated. Full article

(This article belongs to the Special Issue Ambient Assisted Living (AAL): Sensors, Architectures and Applications)

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Graphical abstract

592 KiB

Open AccessArticle

Multi-Sensor Fusion for Enhanced Contextual Awareness of Everyday Activities with Ubiquitous Devices

by John J. Guiry, Pepijn Van de Ven and John Nelson

Sensors 2014, 14(3), 5687-5701; https://doi.org/10.3390/s140305687 - 21 Mar 2014

Cited by 74 | Viewed by 11284

Abstract

In this paper, the authors investigate the role that smart devices, including smartphones and smartwatches, can play in identifying activities of daily living. A feasibility study involving N = 10 participants was carried out to evaluate the devices’ ability to differentiate between nine [...] Read more.

In this paper, the authors investigate the role that smart devices, including smartphones and smartwatches, can play in identifying activities of daily living. A feasibility study involving N = 10 participants was carried out to evaluate the devices’ ability to differentiate between nine everyday activities. The activities examined include walking, running, cycling, standing, sitting, elevator ascents, elevator descents, stair ascents and stair descents. The authors also evaluated the ability of these devices to differentiate indoors from outdoors, with the aim of enhancing contextual awareness. Data from this study was used to train and test five well known machine learning algorithms: C4.5, CART, Naïve Bayes, Multi-Layer Perceptrons and finally Support Vector Machines. Both single and multi-sensor approaches were examined to better understand the role each sensor in the device can play in unobtrusive activity recognition. The authors found overall results to be promising, with some models correctly classifying up to 100% of all instances. Full article

(This article belongs to the Section Sensor Networks)

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499 KiB

Open AccessArticle

An Integrated Photoluminescence Sensing Platform Using a Single-Multi-Mode Fiber Coupler-Based Probe

by Feng Long, Anna Zhu and Hanchang Shi

Sensors 2014, 14(3), 5677-5686; https://doi.org/10.3390/s140305677 - 21 Mar 2014

Cited by 3 | Viewed by 6606

Abstract

We demonstrate an integrated fiber optic photoluminescence sensing platform using a novel single-multi-mode fiber coupler (SMFC)-based probe with high collection efficiency for fluorescence signals. The SMFC, prepared using fused biconical taper technology, not only transmits excitation light, but also collects and transmits fluorescence. [...] Read more.

We demonstrate an integrated fiber optic photoluminescence sensing platform using a novel single-multi-mode fiber coupler (SMFC)-based probe with high collection efficiency for fluorescence signals. The SMFC, prepared using fused biconical taper technology, not only transmits excitation light, but also collects and transmits fluorescence. The entire system does not use complex optical components and rarely requires optical alignment. The simple structure of the SMFC considerably improves the light transmission efficiency, signal-to-noise ratio, and sensitivity of the system. Theoretical and experimental results show that the proposed probe increases the collection efficiency by more than eight-fold compared with a bifurcated fiber probe. The performance of the proposed probe was experimentally evaluated by measuring the fluorescence spectra of well-known targets and a fresh Tall Fescue leaf. Full article

(This article belongs to the Special Issue Photonic Sensors for Industrial, Environmental and Health Monitoring)

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573 KiB

Open AccessArticle

A Caregiver Support Platform within the Scope of an Ambient Assisted Living Ecosystem

by Angelo Costa, Paulo Novais and Ricardo Simoes

Sensors 2014, 14(3), 5654-5676; https://doi.org/10.3390/s140305654 - 20 Mar 2014

Cited by 32 | Viewed by 8393

Abstract

The Ambient Assisted Living (AAL) area is in constant evolution, providing new technologies to users and enhancing the level of security and comfort that is ensured by house platforms. The Ambient Assisted Living for All (AAL4ALL) project aims to develop a new AAL [...] Read more.

The Ambient Assisted Living (AAL) area is in constant evolution, providing new technologies to users and enhancing the level of security and comfort that is ensured by house platforms. The Ambient Assisted Living for All (AAL4ALL) project aims to develop a new AAL concept, supported on a unified ecosystem and certification process that enables a heterogeneous environment. The concepts of Intelligent Environments, Ambient Intelligence, and the foundations of the Ambient Assisted Living are all presented in the framework of this project. In this work, we consider a specific platform developed in the scope of AAL4ALL, called UserAccess. The architecture of the platform and its role within the overall AAL4ALL concept, the implementation of the platform, and the available interfaces are presented. In addition, its feasibility is validated through a series of tests. Full article

(This article belongs to the Special Issue Ambient Assisted Living (AAL): Sensors, Architectures and Applications)

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Graphical abstract

441 KiB

Open AccessArticle

The Dual Carrier ABSK System Based on a FIR Bandpass Filter

by Zhimin Chen, Lenan Wu and Jiwu Wang

Sensors 2014, 14(3), 5644-5653; https://doi.org/10.3390/s140305644 - 20 Mar 2014

Cited by 4 | Viewed by 5458

Abstract

The special impacting filter (SIF) with IIR structure has been used to demodulate ABSK signals. The key points of SIF, including the resonance circuit’s high Q value and the “slope-phase discrimination” character of the filter sideband, are demonstrated in the paper. The FIR [...] Read more.

The special impacting filter (SIF) with IIR structure has been used to demodulate ABSK signals. The key points of SIF, including the resonance circuit’s high Q value and the “slope-phase discrimination” character of the filter sideband, are demonstrated in the paper. The FIR narrow-band bandpass filtering system, which can also provide the impact-filtering effect, is proposed. A dual carrier system of ABSK signals is designed with the proposed FIR filter as its receiver. The simulation results show that the FIR filter can work well. Moreover, compared to the traditional SIF, the proposed FIR filter can not only achieve higher spectral efficiency, but also give better demodulation performance. Full article

(This article belongs to the Section Sensor Networks)

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734 KiB

Open AccessArticle

An Analytical Model for the Performance Analysis of Concurrent Transmission in IEEE 802.15.4

by Cengiz Gezer, Alberto Zanella and Roberto Verdone

Sensors 2014, 14(3), 5622-5643; https://doi.org/10.3390/s140305622 - 20 Mar 2014

Cited by 5 | Viewed by 5941

Abstract

Interference is a serious cause of performance degradation for IEEE802.15.4 devices. The effect of concurrent transmissions in IEEE 802.15.4 has been generally investigated by means of simulation or experimental activities. In this paper, a mathematical framework for the derivation of chip, symbol and [...] Read more.

Interference is a serious cause of performance degradation for IEEE802.15.4 devices. The effect of concurrent transmissions in IEEE 802.15.4 has been generally investigated by means of simulation or experimental activities. In this paper, a mathematical framework for the derivation of chip, symbol and packet error probability of a typical IEEE 802.15.4 receiver in the presence of interference is proposed. Both non-coherent and coherent demodulation schemes are considered by our model under the assumption of the absence of thermal noise. Simulation results are also added to assess the validity of the mathematical framework when the effect of thermal noise cannot be neglected. Numerical results show that the proposed analysis is in agreement with the measurement results on the literature under realistic working conditions. Full article

(This article belongs to the Section Sensor Networks)

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847 KiB

Open AccessArticle

Development of an Electrochemical Sensing Technique for Rapid Genotyping of Hepatitis B Virus

by Jinyuan Chen, Shaohuang Weng, Qingqiong Chen, Ailin Liu, Fengqing Wang, Jing Chen, Qiang Yi, Qicai Liu and Xinhua Lin

Sensors 2014, 14(3), 5611-5621; https://doi.org/10.3390/s140305611 - 20 Mar 2014

Cited by 5 | Viewed by 7015

Abstract

Objective: To develop a convenient; sensitive; accurate; and economical technique for genotyping of hepatitis B viruses (HBVs). Methods: The mercapto-modified B1; B2; C1; and C2-specific genotyping probes consisted of two probes for each HBV genotype that served as a double verification [...] Read more.

Objective: To develop a convenient; sensitive; accurate; and economical technique for genotyping of hepatitis B viruses (HBVs). Methods: The mercapto-modified B1; B2; C1; and C2-specific genotyping probes consisted of two probes for each HBV genotype that served as a double verification system. These probes were fixed on the surface of No. 1; 2; 3; and 4 gold electrodes; respectively; via Au-S bonds. Different charge generated by the binding of RuHex to phosphate groups of the DNA backbone before and after hybridization was used for distinguishing the different genotypes. Results: During hybridization with genotype B; the charges detected at the No. 1 and 2 electrodes were significantly increased; while the charge at the No. 3 and 4 electrodes did not change significantly. During hybridization with genotype C; the charges detected at No. 3 and 4 electrodes were significantly increased; while the signals remained unchanged at the No. 1 and 2 electrodes. During hybridization with mixed genotypes (B and C); the charges detected at all four electrodes were significantly increased. The linear range of detection was 10^–7 to 10^–10 mol/L and the sensitivity for detecting mixed B (10%) or C (10%). Conclusions: Rapid genotyping of HBVs based on electrochemical sensing is simple, has good specificity; and can greatly reduce the cost. This method can be used for sensitive detection of mixed B and C HBV genotypes. Full article

(This article belongs to the Section Biosensors)

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486 KiB

Open AccessArticle

On the Acoustic Filtering of the Pipe and Sensor in a Buried Plastic Water Pipe and its Effect on Leak Detection: An Experimental Investigation

by Fabrício Almeida, Michael Brennan, Phillip Joseph, Stuart Whitfield, Simon Dray and Amarildo Paschoalini

Sensors 2014, 14(3), 5595-5610; https://doi.org/10.3390/s140305595 - 20 Mar 2014

Cited by 83 | Viewed by 15811

Abstract

Acoustic techniques have been used for many years to find and locate leaks in buried water distribution systems. Hydrophones and accelerometers are typically used as sensors. Although geophones could be used as well, they are not generally used for leak detection. A simple [...] Read more.

Acoustic techniques have been used for many years to find and locate leaks in buried water distribution systems. Hydrophones and accelerometers are typically used as sensors. Although geophones could be used as well, they are not generally used for leak detection. A simple acoustic model of the pipe and the sensors has been proposed previously by some of the authors of this paper, and their model was used to explain some of the features observed in measurements. However, simultaneous measurements of a leak using all three sensor-types in controlled conditions for plastic pipes has not been reported to-date and hence they have not yet been compared directly. This paper fills that gap in knowledge. A set of measurements was made on a bespoke buried plastic water distribution pipe test rig to validate the previously reported analytical model. There is qualitative agreement between the experimental results and the model predictions in terms of the differing filtering properties of the pipe-sensor systems. A quality measure for the data is also presented, which is the ratio of the bandwidth over which the analysis is carried out divided by the centre frequency of this bandwidth. Based on this metric, the accelerometer was found to be the best sensor to use for the test rig described in this paper. However, for a system in which the distance between the sensors is large or the attenuation factor of the system is high, then it would be advantageous to use hydrophones, even though they are invasive sensors. Full article

(This article belongs to the Special Issue Sensors for Fluid Leak Detection)

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666 KiB

Open AccessArticle

Improving Data Quality with an Accumulated Reputation Model in Participatory Sensing Systems

by Ruiyun Yu, Rui Liu, Xingwei Wang and Jiannong Cao

Sensors 2014, 14(3), 5573-5594; https://doi.org/10.3390/s140305573 - 20 Mar 2014

Cited by 20 | Viewed by 7268

Abstract

The ubiquity of mobile devices brings forth a sensing paradigm, participatory sensing, to collect and interpret sensory information from the environment. Participants join in multifarious sensing tasks and share their data. The sensing result can be obtained in light of shared data. It [...] Read more.

The ubiquity of mobile devices brings forth a sensing paradigm, participatory sensing, to collect and interpret sensory information from the environment. Participants join in multifarious sensing tasks and share their data. The sensing result can be obtained in light of shared data. It is not uncommon that some corrupted data is provided by participants, which makes sensing result unreliable accordingly. To address this nontrivial issue, we proposed the accumulated reputation model (ARM) to improve the accuracy of the sensing result. In ARM, participants’ reputation will be computed and accumulated based on their sensing data. The sensing data from reputable participants make higher contributions to the sensing result. ARM performs well on calculating accurate sensing results, even in extreme scenarios, where there are many inexperienced or malicious participants. Full article

(This article belongs to the Section Sensor Networks)

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4456 KiB

Open AccessArticle

Estimates of Minor Ocean Tide Loading Displacement and Its Impact on Continuous GPS Coordinate Time Series

by Zhao Li, Weiping Jiang, Wenwu Ding, Liansheng Deng and Lifeng Peng

Sensors 2014, 14(3), 5552-5572; https://doi.org/10.3390/s140305552 - 20 Mar 2014

Cited by 13 | Viewed by 6868

Abstract

The site displacement due to ocean tidal loading is regarded as one of the largest uncertainties in precise geodetic positioning measurements, among which the effect of minor ocean tides (MOT), except for the 11 main tidal constituents, are sometimes neglected in routine precise [...] Read more.

The site displacement due to ocean tidal loading is regarded as one of the largest uncertainties in precise geodetic positioning measurements, among which the effect of minor ocean tides (MOT), except for the 11 main tidal constituents, are sometimes neglected in routine precise global positioning system (GPS) data processing. We find that MOT can cause large vertical loading displacements with peak-to-peak variations reaching more than 8 mm at coastal/island stations. The impact of MOT on the 24-hour GPS solution is slightly larger than the magnitude of MOT loading itself, with peak-to-peak displacement variation at about 10 mm for the horizontal and 30 mm for the vertical components. We also find that the vertical velocity of all the selected stations in the Southwest Pacific was reduced by more than 10% after considering the MOT effect, while stations with weighted root mean square reduced data account for 62%, 59%, and 36% for the up, east, and north components respectively, in particular for most coastal/island stations. Furthermore, MOT correction could significantly reduce the annual signal of the global stacked east component, the near fortnightly and the long-term periodic signals in the up component. The power of some anomalous harmonics of 1.04 cycle per year is also decreased to some extent. These results further proved the benefits of MOT correction in precise GPS data processing. Full article

(This article belongs to the Section Remote Sensors)

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639 KiB

Open AccessArticle

Adaptive Preheating Duration Control for Low-Power Ambient Air Quality Sensor Networks

by Yoonchul Baek, Mahin K. Atiq and Hyung Seok Kim

Sensors 2014, 14(3), 5536-5551; https://doi.org/10.3390/s140305536 - 20 Mar 2014

Cited by 2 | Viewed by 6371

Abstract

Ceramic gas sensors used for measuring ambient air quality have features suitable for practical applications such as healthcare and air quality management, but have a major drawback—large power consumption to preheat the sensor for accurate measurements. In this paper; the adaptive preheating duration [...] Read more.

Ceramic gas sensors used for measuring ambient air quality have features suitable for practical applications such as healthcare and air quality management, but have a major drawback—large power consumption to preheat the sensor for accurate measurements. In this paper; the adaptive preheating duration control (APC) method is proposed to reduce the power consumption of ambient air quality sensor networks. APC reduces the duration of unnecessary preheating, thereby alleviating power consumption. Furthermore, the APC can allow systems to meet user requirements such as accuracy and periodicity factor when detecting the concentration of a target gas. A performance evaluation of the power consumption of gas sensors is conducted with various user requirements and factors that affect the preheating duration of the gas sensor. This shows that the power consumption of the APC is lower than that of continuous power supply methods and constant power supply/cutoff methods. Full article

(This article belongs to the Special Issue Ambient Assisted Living (AAL): Sensors, Architectures and Applications)

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9250 KiB

Open AccessArticle

Samba: A Real-Time Motion Capture System Using Wireless Camera Sensor Networks

by Hyeongseok Oh, Geonho Cha and Songhwai Oh

Sensors 2014, 14(3), 5516-5535; https://doi.org/10.3390/s140305516 - 20 Mar 2014

Cited by 6 | Viewed by 10568

Abstract

There is a growing interest in 3D content following the recent developments in 3D movies, 3D TVs and 3D smartphones. However, 3D content creation is still dominated by professionals, due to the high cost of 3D motion capture instruments. The availability of a [...] Read more.

There is a growing interest in 3D content following the recent developments in 3D movies, 3D TVs and 3D smartphones. However, 3D content creation is still dominated by professionals, due to the high cost of 3D motion capture instruments. The availability of a low-cost motion capture system will promote 3D content generation by general users and accelerate the growth of the 3D market. In this paper, we describe the design and implementation of a real-time motion capture system based on a portable low-cost wireless camera sensor network. The proposed system performs motion capture based on the data-driven 3D human pose reconstruction method to reduce the computation time and to improve the 3D reconstruction accuracy. The system can reconstruct accurate 3D full-body poses at 16 frames per second using only eight markers on the subject’s body. The performance of the motion capture system is evaluated extensively in experiments. Full article

(This article belongs to the Section Sensor Networks)

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775 KiB

Open AccessArticle

Analytical Calculation of Sensing Parameters on Carbon Nanotube Based Gas Sensors

by Elnaz Akbari, Zolkafle Buntat, Mohd Hafizi Ahmad, Aria Enzevaee, Rubiyah Yousof, Syed Muhammad Zafar Iqbal, Mohammad Taghi. Ahmadi, Muhammad Abu Bakar Sidik and Hediyeh Karimi

Sensors 2014, 14(3), 5502-5515; https://doi.org/10.3390/s140305502 - 20 Mar 2014

Cited by 38 | Viewed by 12110

Abstract

Carbon Nanotubes (CNTs) are generally nano-scale tubes comprising a network of carbon atoms in a cylindrical setting that compared with silicon counterparts present outstanding characteristics such as high mechanical strength, high sensing capability and large surface-to-volume ratio. These characteristics, in addition to the [...] Read more.

Carbon Nanotubes (CNTs) are generally nano-scale tubes comprising a network of carbon atoms in a cylindrical setting that compared with silicon counterparts present outstanding characteristics such as high mechanical strength, high sensing capability and large surface-to-volume ratio. These characteristics, in addition to the fact that CNTs experience changes in their electrical conductance when exposed to different gases, make them appropriate candidates for use in sensing/measuring applications such as gas detection devices. In this research, a model for a Field Effect Transistor (FET)-based structure has been developed as a platform for a gas detection sensor in which the CNT conductance change resulting from the chemical reaction between NH₃ and CNT has been employed to model the sensing mechanism with proposed sensing parameters. The research implements the same FET-based structure as in the work of Peng et al. on nanotube-based NH₃ gas detection. With respect to this conductance change, the I–V characteristic of the CNT is investigated. Finally, a comparative study shows satisfactory agreement between the proposed model and the experimental data from the mentioned research. Full article

(This article belongs to the Section Chemical Sensors)

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880 KiB

Open AccessArticle

Improved Algorithms for the Classification of Rough Rice Using a Bionic Electronic Nose Based on PCA and the Wilks Distribution

by Sai Xu, Zhiyan Zhou, Huazhong Lu, Xiwen Luo and Yubin Lan

Sensors 2014, 14(3), 5486-5501; https://doi.org/10.3390/s140305486 - 19 Mar 2014

Cited by 31 | Viewed by 7715

Abstract

Principal Component Analysis (PCA) is one of the main methods used for electronic nose pattern recognition. However, poor classification performance is common in classification and recognition when using regular PCA. This paper aims to improve the classification performance of regular PCA based on [...] Read more.

Principal Component Analysis (PCA) is one of the main methods used for electronic nose pattern recognition. However, poor classification performance is common in classification and recognition when using regular PCA. This paper aims to improve the classification performance of regular PCA based on the existing Wilks ?-statistic (i.e., combined PCA with the Wilks distribution). The improved algorithms, which combine regular PCA with the Wilks ?-statistic, were developed after analysing the functionality and defects of PCA. Verification tests were conducted using a PEN3 electronic nose. The collected samples consisted of the volatiles of six varieties of rough rice (Zhongxiang1, Xiangwan13, Yaopingxiang, WufengyouT025, Pin 36, and Youyou122), grown in same area and season. The first two principal components used as analysis vectors cannot perform the rough rice varieties classification task based on a regular PCA. Using the improved algorithms, which combine the regular PCA with the Wilks ?-statistic, many different principal components were selected as analysis vectors. The set of data points of the Mahalanobis distance between each of the varieties of rough rice was selected to estimate the performance of the classification. The result illustrates that the rough rice varieties classification task is achieved well using the improved algorithm. A Probabilistic Neural Networks (PNN) was also established to test the effectiveness of the improved algorithms. The first two principal components (namely PC1 and PC2) and the first and fifth principal component (namely PC1 and PC5) were selected as the inputs of PNN for the classification of the six rough rice varieties. The results indicate that the classification accuracy based on the improved algorithm was improved by 6.67% compared to the results of the regular method. These results prove the effectiveness of using the Wilks ?-statistic to improve the classification accuracy of the regular PCA approach. The results also indicate that the electronic nose provides a non-destructive and rapid classification method for rough rice. Full article

(This article belongs to the Special Issue Gas Sensors - 2013)

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541 KiB

Open AccessArticle

Gait Event Detection during Stair Walking Using a Rate Gyroscope

by Paola Catalfamo Formento, Ruben Acevedo, Salim Ghoussayni and David Ewins

Sensors 2014, 14(3), 5470-5485; https://doi.org/10.3390/s140305470 - 19 Mar 2014

Cited by 60 | Viewed by 9128

Abstract

Gyroscopes have been proposed as sensors for ambulatory gait analysis and functional electrical stimulation systems. These applications often require detection of the initial contact (IC) of the foot with the floor and/or final contact or foot off (FO) from the floor during outdoor [...] Read more.

Gyroscopes have been proposed as sensors for ambulatory gait analysis and functional electrical stimulation systems. These applications often require detection of the initial contact (IC) of the foot with the floor and/or final contact or foot off (FO) from the floor during outdoor walking. Previous investigations have reported the use of a single gyroscope placed on the shank for detection of IC and FO on level ground and incline walking. This paper describes the evaluation of a gyroscope placed on the shank for determination of IC and FO in subjects ascending and descending a set of stairs. Performance was compared with a reference pressure measurement system. The absolute mean difference between the gyroscope and the reference was less than 45 ms for IC and better than 135 ms for FO for both activities. Detection success was over 93%. These results provide preliminary evidence supporting the use of a gyroscope for gait event detection when walking up and down stairs. Full article

(This article belongs to the Special Issue Wearable Gait Sensors)

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661 KiB

Open AccessArticle

Fibre Optic System for Monitoring Rotational Seismic Phenomena

by Anna Kurzych, Leszek R. Jaroszewicz, Zbigniew Krajewski, Krzysztof P. Teisseyre and Jerzy K. Kowalski

Sensors 2014, 14(3), 5459-5469; https://doi.org/10.3390/s140305459 - 19 Mar 2014

Cited by 21 | Viewed by 6557

Abstract

We outline the development and the application in a field test of the Autonomous Fibre-Optic Rotational Seismograph (AFORS), which utilizes the Sagnac effect for a direct measurement of the seismic-origin rotations of the ground. The main advantage of AFORS is its complete insensitivity [...] Read more.

We outline the development and the application in a field test of the Autonomous Fibre-Optic Rotational Seismograph (AFORS), which utilizes the Sagnac effect for a direct measurement of the seismic-origin rotations of the ground. The main advantage of AFORS is its complete insensitivity to linear motions, as well as a direct measurement of rotational components emitted during seismic events. The presented system contains a special autonomous signal processing unit which optimizes its operation for the measurement of rotation motions, whereas the applied telemetric system based on the Internet allows for an AFORS remote control. The laboratory investigation of such two devices indicated that they keep an accuracy of no less than 5.1 × 10⁻⁹ to 5.5 × 10⁻⁸ rad/s in the detection frequency band from 0.83~106.15 Hz and protect linear changes of sensitivity in the above bandpass. Some experimental results of an AFORS-1 application for a continuous monitoring of the rotational events in the Książ (Poland) seismological observatory are also presented. Full article

(This article belongs to the Special Issue Photonic Sensors for Industrial, Environmental and Health Monitoring)

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976 KiB

Open AccessArticle

Small Private Key MQPKS on an Embedded Microprocessor

by Hwajeong Seo, Jihyun Kim, Jongseok Choi, Taehwan Park, Zhe Liu and Howon Kim

Sensors 2014, 14(3), 5441-5458; https://doi.org/10.3390/s140305441 - 19 Mar 2014

Cited by 5 | Viewed by 8733

Abstract

Multivariate quadratic (MQ) cryptography requires the use of long public and private keys to ensure a sufficient security level, but this is not favorable to embedded systems, which have limited system resources. Recently, various approaches to MQ cryptography using reduced public [...] Read more.

Multivariate quadratic (MQ) cryptography requires the use of long public and private keys to ensure a sufficient security level, but this is not favorable to embedded systems, which have limited system resources. Recently, various approaches to MQ cryptography using reduced public keys have been studied. As a result of this, at CHES2011 (Cryptographic Hardware and Embedded Systems, 2011), a small public key MQ scheme, was proposed, and its feasible implementation on an embedded microprocessor was reported at CHES2012. However, the implementation of a small private key MQ scheme was not reported. For efficient implementation, random number generators can contribute to reduce the key size, but the cost of using a random number generator is much more complex than computing MQ on modern microprocessors. Therefore, no feasible results have been reported on embedded microprocessors. In this paper, we propose a feasible implementation on embedded microprocessors for a small private key MQ scheme using a pseudo-random number generator and hash function based on a block-cipher exploiting a hardware Advanced Encryption Standard (AES) accelerator. To speed up the performance, we apply various implementation methods, including parallel computation, on-the-fly computation, optimized logarithm representation, vinegar monomials and assembly programming. The proposed method reduces the private key size by about 99.9% and boosts signature generation and verification by 5.78% and 12.19% than previous results in CHES2012. Full article

(This article belongs to the Section Physical Sensors)

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356 KiB

Open AccessArticle

Experimental Investigations on Airborne Gravimetry Based on Compressed Sensing

by Yapeng Yang, Meiping Wu, Jinling Wang, Kaidong Zhang, Juliang Cao and Shaokun Cai

Sensors 2014, 14(3), 5426-5440; https://doi.org/10.3390/s140305426 - 18 Mar 2014

Cited by 1 | Viewed by 6491

Abstract

Gravity surveys are an important research topic in geophysics and geodynamics. This paper investigates a method for high accuracy large scale gravity anomaly data reconstruction. Based on the airborne gravimetry technology, a flight test was carried out in China with the strap-down airborne [...] Read more.

Gravity surveys are an important research topic in geophysics and geodynamics. This paper investigates a method for high accuracy large scale gravity anomaly data reconstruction. Based on the airborne gravimetry technology, a flight test was carried out in China with the strap-down airborne gravimeter (SGA-WZ) developed by the Laboratory of Inertial Technology of the National University of Defense Technology. Taking into account the sparsity of airborne gravimetry by the discrete Fourier transform (DFT), this paper proposes a method for gravity anomaly data reconstruction using the theory of compressed sensing (CS). The gravity anomaly data reconstruction is an ill-posed inverse problem, which can be transformed into a sparse optimization problem. This paper uses the zero-norm as the objective function and presents a greedy algorithm called Orthogonal Matching Pursuit (OMP) to solve the corresponding minimization problem. The test results have revealed that the compressed sampling rate is approximately 14%, the standard deviation of the reconstruction error by OMP is 0.03 mGal and the signal-to-noise ratio (SNR) is 56.48 dB. In contrast, the standard deviation of the reconstruction error by the existing nearest-interpolation method (NIPM) is 0.15 mGal and the SNR is 42.29 dB. These results have shown that the OMP algorithm can reconstruct the gravity anomaly data with higher accuracy and fewer measurements. Full article

(This article belongs to the Section Physical Sensors)

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539 KiB

Open AccessArticle

Synthesis of Three Dimensional Nickel Cobalt Oxide Nanoneedles on Nickel Foam, Their Characterization and Glucose Sensing Application

by Mushtaque Hussain, Zafar Hussain Ibupoto, Mazhar Ali Abbasi, Xianjie Liu, Omer Nur and Magnus Willander

Sensors 2014, 14(3), 5415-5425; https://doi.org/10.3390/s140305415 - 18 Mar 2014

Cited by 53 | Viewed by 11045

Abstract

In the present work, NiCo₂O₄ nanostructures are fabricated in three dimensions (3D) on nickel foam by the hydrothermal method. The nanomaterial was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The nanostructures exhibit nanoneedle-like [...] Read more.

In the present work, NiCo₂O₄ nanostructures are fabricated in three dimensions (3D) on nickel foam by the hydrothermal method. The nanomaterial was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The nanostructures exhibit nanoneedle-like morphology grown in 3D with good crystalline quality. The nanomaterial is composed of nickel, cobalt and oxygen atoms. By using the favorable porosity of the nanomaterial and the substrate itself, a sensitive glucose sensor is proposed by immobilizing glucose oxidase. The presented glucose sensor has shown linear response over a wide range of glucose concentrations from 0.005 mM to 15 mM with a sensitivity of 91.34 mV/decade and a fast response time of less than 10 s. The NiCo₂O₄ nanostructures-based glucose sensor has shown excellent reproducibility, repeatability and stability. The sensor showed negligible response to the normal concentrations of common interferents with glucose sensing, including uric acid, dopamine and ascorbic acid. All these favorable advantages of the fabricated glucose sensor suggest that it may have high potential for the determination of glucose in biological samples, food and other related areas. Full article

(This article belongs to the Section Chemical Sensors)

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1595 KiB

Open AccessArticle

Maestro: An Orchestration Framework for Large-Scale WSN Simulations

by Laurynas Riliskis and Evgeny Osipov

Sensors 2014, 14(3), 5392-5414; https://doi.org/10.3390/s140305392 - 18 Mar 2014

Cited by 5 | Viewed by 7267

Abstract

Contemporary wireless sensor networks (WSNs) have evolved into large and complex systems and are one of the main technologies used in cyber-physical systems and the Internet of Things. Extensive research on WSNs has led to the development of diverse solutions at all levels [...] Read more.

Contemporary wireless sensor networks (WSNs) have evolved into large and complex systems and are one of the main technologies used in cyber-physical systems and the Internet of Things. Extensive research on WSNs has led to the development of diverse solutions at all levels of software architecture, including protocol stacks for communications. This multitude of solutions is due to the limited computational power and restrictions on energy consumption that must be accounted for when designing typical WSN systems. It is therefore challenging to develop, test and validate even small WSN applications, and this process can easily consume significant resources. Simulations are inexpensive tools for testing, verifying and generally experimenting with new technologies in a repeatable fashion. Consequently, as the size of the systems to be tested increases, so does the need for large-scale simulations. This article describes a tool called Maestro for the automation of large-scale simulation and investigates the feasibility of using cloud computing facilities for such task. Using tools that are built into Maestro, we demonstrate a feasible approach for benchmarking cloud infrastructure in order to identify cloud Virtual Machine (VM)instances that provide an optimal balance of performance and cost for a given simulation. Full article

(This article belongs to the Section Sensor Networks)

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Open AccessReview

Modeling Users, Context and Devices for Ambient Assisted Living Environments

by Eduardo Castillejo, Aitor Almeida, Diego López-de-Ipiña and Liming Chen

Sensors 2014, 14(3), 5354-5391; https://doi.org/10.3390/s140305354 - 17 Mar 2014

Cited by 23 | Viewed by 9312

Abstract

The participation of users within AAL environments is increasing thanks to the capabilities of the current wearable devices. Furthermore, the significance of considering user’s preferences, context conditions and device’s capabilities help smart environments to personalize services and resources for them. Being aware of [...] Read more.

The participation of users within AAL environments is increasing thanks to the capabilities of the current wearable devices. Furthermore, the significance of considering user’s preferences, context conditions and device’s capabilities help smart environments to personalize services and resources for them. Being aware of different characteristics of the entities participating in these situations is vital for reaching the main goals of the corresponding systems efficiently. To collect different information from these entities, it is necessary to design several formal models which help designers to organize and give some meaning to the gathered data. In this paper, we analyze several literature solutions for modeling users, context and devices considering different approaches in the Ambient Assisted Living domain. Besides, we remark different ongoing standardization works in this area. We also discuss the used techniques, modeled characteristics and the advantages and drawbacks of each approach to finally draw several conclusions about the reviewed works. Full article

(This article belongs to the Special Issue Ambient Assisted Living (AAL): Sensors, Architectures and Applications)

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1538 KiB

Open AccessArticle

Calibration between Color Camera and 3D LIDAR Instruments with a Polygonal Planar Board

by Yoonsu Park, Seokmin Yun, Chee Sun Won, Kyungeun Cho, Kyhyun Um and Sungdae Sim

Sensors 2014, 14(3), 5333-5353; https://doi.org/10.3390/s140305333 - 17 Mar 2014

Cited by 198 | Viewed by 15455

Abstract

Calibration between color camera and 3D Light Detection And Ranging (LIDAR) equipment is an essential process for data fusion. The goal of this paper is to improve the calibration accuracy between a camera and a 3D LIDAR. In particular, we are interested in [...] Read more.

Calibration between color camera and 3D Light Detection And Ranging (LIDAR) equipment is an essential process for data fusion. The goal of this paper is to improve the calibration accuracy between a camera and a 3D LIDAR. In particular, we are interested in calibrating a low resolution 3D LIDAR with a relatively small number of vertical sensors. Our goal is achieved by employing a new methodology for the calibration board, which exploits 2D-3D correspondences. The 3D corresponding points are estimated from the scanned laser points on the polygonal planar board with adjacent sides. Since the lengths of adjacent sides are known, we can estimate the vertices of the board as a meeting point of two projected sides of the polygonal board. The estimated vertices from the range data and those detected from the color image serve as the corresponding points for the calibration. Experiments using a low-resolution LIDAR with 32 sensors show robust results. Full article

(This article belongs to the Section Physical Sensors)

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2802 KiB

Open AccessReview

Flexible Tactile Sensing Based on Piezoresistive Composites: A Review

by Stefano Stassi, Valentina Cauda, Giancarlo Canavese and Candido Fabrizio Pirri

Sensors 2014, 14(3), 5296-5332; https://doi.org/10.3390/s140305296 - 14 Mar 2014

Cited by 358 | Viewed by 29267

Abstract

The large expansion of the robotic field in the last decades has created a growing interest in the research and development of tactile sensing solutions for robot hand and body integration. Piezoresistive composites are one of the most widely employed materials for this [...] Read more.

The large expansion of the robotic field in the last decades has created a growing interest in the research and development of tactile sensing solutions for robot hand and body integration. Piezoresistive composites are one of the most widely employed materials for this purpose, combining simple and low cost preparation with high flexibility and conformability to surfaces, low power consumption, and the use of simple read-out electronics. This work provides a review on the different type of composite materials, classified according to the conduction mechanism and analyzing the physics behind it. In particular piezoresistors, strain gauges, percolative and quantum tunnelling devices are reviewed here, with a perspective overview on the most used filler types and polymeric matrices. A description of the state-of-the-art of the tactile sensor solutions from the point of view of the architecture, the design and the performance is also reviewed, with a perspective outlook on the main promising applications. Full article

(This article belongs to the Special Issue Tactile Sensors and Sensing Systems)

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883 KiB

Open AccessArticle

Infrared Sensor-Based Temperature Control for Domestic Induction Cooktops

by Javier Lasobras, Rafael Alonso, Claudio Carretero, Enrique Carretero and Eduardo Imaz

Sensors 2014, 14(3), 5278-5295; https://doi.org/10.3390/s140305278 - 14 Mar 2014

Cited by 18 | Viewed by 22360

Abstract

In this paper, a precise real-time temperature control system based on infrared (IR) thermometry for domestic induction cooking is presented. The temperature in the vessel constitutes the control variable of the closed-loop power control system implemented in a commercial induction cooker. A proportional-integral [...] Read more.

In this paper, a precise real-time temperature control system based on infrared (IR) thermometry for domestic induction cooking is presented. The temperature in the vessel constitutes the control variable of the closed-loop power control system implemented in a commercial induction cooker. A proportional-integral controller is applied to establish the output power level in order to reach the target temperature. An optical system and a signal conditioning circuit have been implemented. For the signal processing a microprocessor with 12-bit ADC and a sampling rate of 1 Ksps has been used. The analysis of the contributions to the infrared radiation permits the definition of a procedure to estimate the temperature of the vessel with a maximum temperature error of 5 °C in the range between 60 and 250 °C for a known cookware emissivity. A simple and necessary calibration procedure with a black-body sample is presented. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Spain 2013)

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14098 KiB

Open AccessArticle

Research on the Signal Process of a Bell-Shaped Vibratory Angular Rate Gyro

by Zhong Su, Ning Liu, Qing Li, Mengyin Fu, Hong Liu and Junfang Fan

Sensors 2014, 14(3), 5254-5277; https://doi.org/10.3390/s140305254 - 13 Mar 2014

Cited by 11 | Viewed by 7214

Abstract

A bell-shaped vibratory angular rate gyro, which is inspired by the Chinese traditional bell, is a kind of axisymmetric shell resonator gyroscope. Its sensitive element is a vibratory-like Chinese traditional bell, using a piezoelectric element on the wall of the vibrator to detect [...] Read more.

A bell-shaped vibratory angular rate gyro, which is inspired by the Chinese traditional bell, is a kind of axisymmetric shell resonator gyroscope. Its sensitive element is a vibratory-like Chinese traditional bell, using a piezoelectric element on the wall of the vibrator to detect the standing wave’s precession to solve the input angular rate. This work mainly studies the circuit system of a bell-shaped vibratory angular rate gyro. It discusses the process of circuit system design, analysis and experiment, in detail, providing the foundation to develop a bell-shaped vibratory angular rate gyro. Since the bell-shaped resonator’s curved structure has the characteristics of large noise in the piezoelectric signal and large harmonics, this paper analyzes its working and signal detection method, then gives the whole plan of the circuit system, including the drive module, the detection module and the control loop. It also studies every part of the whole system, gives a detailed design and analysis process and proves part of the circuit system using digital simulation. At the end of the article, the test result of the circuit system shows that it can remove the disadvantages of the curved structure having large noise in the piezoelectric signal and large harmonics and is more effective at solving the input angular rate. Full article

(This article belongs to the Section Physical Sensors)

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338 KiB

Open AccessArticle

A Constant Speed Changing Rate and Constant Turn Rate Model for Maneuvering Target Tracking

by Guan Zhai, Huadong Meng and Xiqin Wang

Sensors 2014, 14(3), 5239-5253; https://doi.org/10.3390/s140305239 - 13 Mar 2014

Cited by 26 | Viewed by 7976

Abstract

This paper addresses the problem of modeling maneuvering target motion in tracking applications. A target trajectory can typically be divided into segments with different dynamic motion modes, such as a constant velocity motion, a constant acceleration motion or a constant turn rate motion. [...] Read more.

This paper addresses the problem of modeling maneuvering target motion in tracking applications. A target trajectory can typically be divided into segments with different dynamic motion modes, such as a constant velocity motion, a constant acceleration motion or a constant turn rate motion. To integrate the different motion modes into a uniform model, a Constant Speed Changing Rate and Constant Turn Rate (CSCRCTR) model is proposed. A new state vector is defined, and the state transition function is derived. Based on the CSCRCTR model, we present a tracking algorithm using a particle filter. The performances of the CSCRCTR model, the uniform model (UM) and the interacting multiple model (IMM) for tracking a simulated maneuvering target are compared and show that the CSCRCTR model maintains a good consistency for different types of motions and achieves better accuracy than UM and IMM when maneuvers occur. Full article

(This article belongs to the Section Physical Sensors)

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Graphical abstract

1223 KiB

Open AccessArticle

Olfaction-Inspired Sensing Using a Sensor System with Molecular Recognition and Optimal Classification Ability for Comprehensive Detection of Gases

by Masahiro Imahashi, Masashi Watanabe, Sunil Kumar Jha and Kenshi Hayashi

Sensors 2014, 14(3), 5221-5238; https://doi.org/10.3390/s140305221 - 12 Mar 2014

Cited by 5 | Viewed by 7839

Abstract

In this study, we examined the comprehensive detection of numerous volatile molecules based on the olfactory information constructed by using olfaction-inspired sensor technology. The sensor system can simultaneously detect multiple odors by the separation and condensation ability of molecularly imprinted filtering adsorbents (MIFAs), [...] Read more.

In this study, we examined the comprehensive detection of numerous volatile molecules based on the olfactory information constructed by using olfaction-inspired sensor technology. The sensor system can simultaneously detect multiple odors by the separation and condensation ability of molecularly imprinted filtering adsorbents (MIFAs), where a MIP filter with a molecular sieve was deposited on a polydimethylsiloxane (PDMS) substrate. The adsorption properties of MIFAs were evaluated using the solid-phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS). The results demonstrated that the system embedded with MIFAs possesses high sensitivity and specific selectivity. The digitization and comprehensive classification of odors were accomplished by using artificial odor maps constructed through this system. Full article

(This article belongs to the Section Chemical Sensors)

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640 KiB

Open AccessArticle

Force Sensor Attachable to Thin Fiberscopes/Endoscopes Utilizing High Elasticity Fabric

by Tetsuyou Watanabe, Takanobu Iwai, Yoshinori Fujihira, Lina Wakako, Hiroyuki Kagawa and Takeshi Yoneyama

Sensors 2014, 14(3), 5207-5220; https://doi.org/10.3390/s140305207 - 12 Mar 2014

Cited by 21 | Viewed by 7722

Abstract

An endoscope/fiberscope is a minimally invasive tool used for directly observing tissues in areas deep inside the human body where access is limited. However, this tool only yields visual information. If force feedback information were also available, endoscope/fiberscope operators would be able to [...] Read more.

An endoscope/fiberscope is a minimally invasive tool used for directly observing tissues in areas deep inside the human body where access is limited. However, this tool only yields visual information. If force feedback information were also available, endoscope/fiberscope operators would be able to detect indurated areas that are visually hard to recognize. Furthermore, obtaining such feedback information from tissues in areas where collecting visual information is a challenge would be highly useful. The major obstacle is that such force information is difficult to acquire. This paper presents a novel force sensing system that can be attached to a very thin fiberscope/endoscope. To ensure a small size, high resolution, easy sterilization, and low cost, the proposed force visualization–based system uses a highly elastic material—panty stocking fabric. The paper also presents the methodology for deriving the force value from the captured image. The system has a resolution of less than 0.01 N and sensitivity of greater than 600 pixels/N within the force range of 0–0.2 N. Full article

(This article belongs to the Section Physical Sensors)

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Graphical abstract

368 KiB

Open AccessCommunication

A Polarization Control System for Intensity-Resolved Guided Mode Resonance Sensors

by Sheng-Fu Lin, Fu-Chen Chang, Zhi-Heng Chen, Chih-Ming Wang, Tsung-Hsun Yang, Wen-Yih Chen and Jenq-Yang Chang

Sensors 2014, 14(3), 5198-5206; https://doi.org/10.3390/s140305198 - 12 Mar 2014

Cited by 12 | Viewed by 6758

Abstract

In this study, a polarization-control setup for intensity-resolved guided mode resonance sensors is proposed and demonstrated experimentally. The experimental results are in good agreement with the simulation data based on rigorous coupled wave approach calculations. The proposed intensity-resolved measurement setup transfers polarization ellipses, [...] Read more.

In this study, a polarization-control setup for intensity-resolved guided mode resonance sensors is proposed and demonstrated experimentally. The experimental results are in good agreement with the simulation data based on rigorous coupled wave approach calculations. The proposed intensity-resolved measurement setup transfers polarization ellipses, which are produced from guided mode resonance to a linear polarization state under a buffer solution condition, and then suppresses the signals to dark using a polarization-control set. Hence, any changes in the refractive index results in an increase in the intensity signals. Furthermore, no wavelength-resolved or angular-resolved measurement is needed in this scheme. According to the experimental results, a wide linear detection range of 0.014 refractive index units is achieved and the limit of detection is 1.62E-4 RIU. Full article

(This article belongs to the Section Physical Sensors)

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Sensors, Volume 14, Issue 3 (March 2014) – 101 articles , Pages 3825-5741

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