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14 pages, 2719 KiB

Open AccessArticle

Synchronized High-Speed Vision Sensor Network for Expansion of Field of View

by Akihito Noda, Satoshi Tabata, Masatoshi Ishikawa and Yuji Yamakawa

Sensors 2018, 18(4), 1276; https://doi.org/10.3390/s18041276 - 21 Apr 2018

Cited by 2 | Viewed by 6310

We propose a 500-frames-per-second high-speed vision (HSV) sensor network that acquires frames at a timing that is precisely synchronized across the network. Multiple vision sensor nodes, individually comprising a camera and a PC, are connected via Ethernet for data transmission and for clock [...] Read more.

We propose a 500-frames-per-second high-speed vision (HSV) sensor network that acquires frames at a timing that is precisely synchronized across the network. Multiple vision sensor nodes, individually comprising a camera and a PC, are connected via Ethernet for data transmission and for clock synchronization. A network of synchronized HSV sensors provides a significantly expanded field-of-view compared with that of each individual HSV sensor. In the proposed system, the shutter of each camera is controlled based on the clock of the PC locally provided inside the node, and the shutters are globally synchronized using the Precision Time Protocol (PTP) over the network. A theoretical analysis and experiment results indicate that the shutter trigger skew among the nodes is a few tens of microseconds at most, which is significantly smaller than the frame interval of 1000-fps-class high-speed cameras. Experimental results obtained with the proposed system comprising four nodes demonstrated the ability to capture the propagation of a small displacement along a large-scale structure. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Japan 2017)

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14 pages, 3289 KiB

Open AccessArticle

Evaluation of a Sensor System for Detecting Humans Trapped under Rubble: A Pilot Study

by Di Zhang, Salvatore Sessa, Ritaro Kasai, Sarah Cosentino, Cimarelli Giacomo, Yasuaki Mochida, Hiroya Yamada, Michele Guarnieri and Atsuo Takanishi

Sensors 2018, 18(3), 852; https://doi.org/10.3390/s18030852 - 13 Mar 2018

Cited by 22 | Viewed by 11243

Abstract

Rapid localization of injured survivors by rescue teams to prevent death is a major issue. In this paper, a sensor system for human rescue including three different types of sensors, a CO₂ sensor, a thermal camera, and a microphone, is proposed. The [...] Read more.

Rapid localization of injured survivors by rescue teams to prevent death is a major issue. In this paper, a sensor system for human rescue including three different types of sensors, a CO₂ sensor, a thermal camera, and a microphone, is proposed. The performance of this system in detecting living victims under the rubble has been tested in a high-fidelity simulated disaster area. Results show that the CO₂ sensor is useful to effectively reduce the possible concerned area, while the thermal camera can confirm the correct position of the victim. Moreover, it is believed that the use of microphones in connection with other sensors would be of great benefit for the detection of casualties. In this work, an algorithm to recognize voices or suspected human noise under rubble has also been developed and tested. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Japan 2017)

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21 pages, 1960 KiB

Open AccessArticle

Infrastructure-Less Communication Platform for Off-The-Shelf Android Smartphones

by Takuma Oide, Toru Abe and Takuo Suganuma

Sensors 2018, 18(3), 776; https://doi.org/10.3390/s18030776 - 4 Mar 2018

Cited by 7 | Viewed by 4410

Abstract

As smartphones and other small portable devices become more sophisticated and popular, opportunities for communication and information sharing among such device users have increased. In particular, since it is known that infrastructure-less device-to-device (D2D) communication platforms consisting only of such devices are excellent [...] Read more.

As smartphones and other small portable devices become more sophisticated and popular, opportunities for communication and information sharing among such device users have increased. In particular, since it is known that infrastructure-less device-to-device (D2D) communication platforms consisting only of such devices are excellent in terms of, for example, bandwidth efficiency, efforts are being made to merge their information sharing capabilities with conventional infrastructure. However, efficient multi-hop communication is difficult with the D2D communication protocol, and many conventional D2D communication platforms require modifications of the protocol and terminal operating systems (OSs). In response to these issues, this paper reports on a proposed tree-structured D2D communication platform for Android devices that combines Wi-Fi Direct and Wi-Fi functions. The proposed platform, which is expected to be used with general Android 4.0 (or higher) OS equipped terminals, makes it possible to construct an ad hoc network instantaneously without sharing prior knowledge among participating devices. We will show the feasibility of our proposed platform through its design and demonstrate the implementation of a prototype using real devices. In addition, we will report on our investigation into communication delays and stability based on the number of hops and on terminal performance through experimental confirmation experiments. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Japan 2017)

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11 pages, 3342 KiB

Open AccessArticle

Earable TEMPO: A Novel, Hands-Free Input Device that Uses the Movement of the Tongue Measured with a Wearable Ear Sensor

by Kazuhiro Taniguchi, Hisashi Kondo, Mami Kurosawa and Atsushi Nishikawa

Sensors 2018, 18(3), 733; https://doi.org/10.3390/s18030733 - 1 Mar 2018

Cited by 27 | Viewed by 6288

Abstract

In this study, an earphone-type interface named “earable TEMPO” was developed for hands-free operation, wherein the user can control the device by simply pushing the tongue against the roof of the mouth for about one second. This interface can be used to start [...] Read more.

In this study, an earphone-type interface named “earable TEMPO” was developed for hands-free operation, wherein the user can control the device by simply pushing the tongue against the roof of the mouth for about one second. This interface can be used to start and stop the music from a portable audio player. The earable TEMPO uses an earphone-type sensor equipped with a light emitting diode (LED) and a phototransistor to optically measure shape variations that occur in the external auditory meatus when the tongue is pressed against the roof of the mouth. To evaluate the operation of the earable TEMPO, experiments were performed on five subjects (men and women aged 22–58) while resting, chewing gum (representing mastication), and walking. The average accuracy was 100% while resting and chewing and 99% while walking. The precision was 100% under all conditions. The average recall value of the five subjects was 92%, 90%, and 48% while resting, masticating, and walking, respectively. All subjects were reliably able to perform the action of pressing the tongue against the roof of the mouth. The measured shape variations in the ear canal were highly reproducible, indicating that this method is suitable for various applications such as controlling a portable audio player. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Japan 2017)

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22 pages, 6583 KiB

Open AccessArticle

A Liquid-Surface-Based Three-Axis Inclination Sensor for Measurement of Stage Tilt Motions

by Yuki Shimizu, Satoshi Kataoka, Tatsuya Ishikawa, Yuan-Liu Chen, Xiuguo Chen, Hiraku Matsukuma and Wei Gao

Sensors 2018, 18(2), 398; https://doi.org/10.3390/s18020398 - 30 Jan 2018

Cited by 16 | Viewed by 7459

Abstract

In this paper a new concept of a liquid-surface-based three-axis inclination sensor for evaluation of angular error motion of a precision linear slide, which is often used in the field of precision engineering such as ultra-precision machine tools, coordinate measuring machines (CMMs) and [...] Read more.

In this paper a new concept of a liquid-surface-based three-axis inclination sensor for evaluation of angular error motion of a precision linear slide, which is often used in the field of precision engineering such as ultra-precision machine tools, coordinate measuring machines (CMMs) and so on, is proposed. In the liquid-surface-based three-axis inclination sensor, a reference float mounting a line scale grating having periodic line grating structures is made to float over a liquid surface, while its three-axis angular motion is measured by using an optical sensor head based on the three-axis laser autocollimation capable of measuring three-axis angular motion of the scale grating. As the first step of research, in this paper, theoretical analysis on the angular motion of the reference float about each axis has been carried out based on simplified kinematic models to evaluate the possibility of realizing the proposed concept of a three-axis inclination sensor. In addition, based on the theoretical analyses results, a prototype three-axis inclination sensor has been designed and developed. Through some basic experiments with the prototype, the possibility of simultaneous three-axis inclination measurement by the proposed concept has been verified. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Japan 2017)

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10076 KiB

Open AccessArticle

Hazardous Object Detection by Using Kinect Sensor in a Handle-Type Electric Wheelchair

by Jeyeon Kim, Takaaki Hasegawa and Yuta Sakamoto

Sensors 2017, 17(12), 2936; https://doi.org/10.3390/s17122936 - 18 Dec 2017

Cited by 4 | Viewed by 5409

Abstract

To ensure the safety of a handle-type electric wheelchair (hereinafter, electric wheelchair), this paper describes the applicability of using a Kinect sensor. Ensuring the mobility of elderly people is a particularly important issue to be resolved. An electric wheelchair is useful as a [...] Read more.

To ensure the safety of a handle-type electric wheelchair (hereinafter, electric wheelchair), this paper describes the applicability of using a Kinect sensor. Ensuring the mobility of elderly people is a particularly important issue to be resolved. An electric wheelchair is useful as a means of transportation for elderly people. Considering that the users of electric wheelchairs are elderly people, it is important to ensure the safety of electric wheelchairs at night. To ensure the safety of an electric wheelchair at night, we constructed a hazardous object detection system using commercially available and inexpensive Kinect sensors and examined the applicability of the system. We examined warning timing with consideration to the cognition, judgment, and operation time of elderly people. Based on this, a hazardous object detection area was determined. Furthermore, the detection of static and dynamic hazardous objects was carried out at night and the results showed that the system was able to detect with high accuracy. We also conducted experiments related to dynamic hazardous object detection during daytime. From the above, it showed that the system could be applicable to ensuring the safety of the handle-type electric wheelchair. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Japan 2017)

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12117 KiB

Open AccessArticle

Super-Resolution of Plant Disease Images for the Acceleration of Image-based Phenotyping and Vigor Diagnosis in Agriculture

by Kyosuke Yamamoto, Takashi Togami and Norio Yamaguchi

Sensors 2017, 17(11), 2557; https://doi.org/10.3390/s17112557 - 6 Nov 2017

Cited by 92 | Viewed by 10461

Abstract

Unmanned aerial vehicles (UAVs or drones) are a very promising branch of technology, and they have been utilized in agriculture—in cooperation with image processing technologies—for phenotyping and vigor diagnosis. One of the problems in the utilization of UAVs for agricultural purposes is the [...] Read more.

Unmanned aerial vehicles (UAVs or drones) are a very promising branch of technology, and they have been utilized in agriculture—in cooperation with image processing technologies—for phenotyping and vigor diagnosis. One of the problems in the utilization of UAVs for agricultural purposes is the limitation in flight time. It is necessary to fly at a high altitude to capture the maximum number of plants in the limited time available, but this reduces the spatial resolution of the captured images. In this study, we applied a super-resolution method to the low-resolution images of tomato diseases to recover detailed appearances, such as lesions on plant organs. We also conducted disease classification using high-resolution, low-resolution, and super-resolution images to evaluate the effectiveness of super-resolution methods in disease classification. Our results indicated that the super-resolution method outperformed conventional image scaling methods in spatial resolution enhancement of tomato disease images. The results of disease classification showed that the accuracy attained was also better by a large margin with super-resolution images than with low-resolution images. These results indicated that our approach not only recovered the information lost in low-resolution images, but also exerted a beneficial influence on further image analysis. The proposed approach will accelerate image-based phenotyping and vigor diagnosis in the field, because it not only saves time to capture images of a crop in a cultivation field but also secures the accuracy of these images for further analysis. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Japan 2017)

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4154 KiB

Open AccessArticle

TAMRA/TAMRA Fluorescence Quenching Systems for the Activity Assay of Alkaline Phosphatase

by Akio Shiba, Emiko Kinoshita-Kikuta, Eiji Kinoshita and Tohru Koike

Sensors 2017, 17(8), 1877; https://doi.org/10.3390/s17081877 - 15 Aug 2017

Cited by 15 | Viewed by 8566

Abstract

We introduce two types of fluorescence-quenching assay for alkaline phosphatases (APs) by using a carboxytetramethyl-rhodamine (TAMRA)-labeled phosphate-binding tag molecule (TAMRA-Phos-tag). In the first assay, TAMRA-labeled O-phosphorylethanolamine (TAMRA-PEA) was used as an artificial AP-substrate. TAMRA-Phos-tag specifically captured TAMRA-PEA to form a 1:1 complex [...] Read more.

We introduce two types of fluorescence-quenching assay for alkaline phosphatases (APs) by using a carboxytetramethyl-rhodamine (TAMRA)-labeled phosphate-binding tag molecule (TAMRA-Phos-tag). In the first assay, TAMRA-labeled O-phosphorylethanolamine (TAMRA-PEA) was used as an artificial AP-substrate. TAMRA-Phos-tag specifically captured TAMRA-PEA to form a 1:1 complex at pH 7.4; the intensity of the fluorescence peak of the complex at 580 nm (λ_ex = 523 nm) was significantly reduced to 32% of the average value for the two individual components as a result of the mutual approach of the TAMRA moieties. As TAMRA-PEA was dephosphorylated by AP, the resulting TAMRA-labeled ethanolamine dissociated and the fluorescence increased in a manner dependent on the AP dose and the time. In the second assay, pyrophosphate (PP), a natural AP-substrate, was used as a bridging ligand to form a dimeric TAMRA-Phos-tag complex. The dimerization reduced the fluorescence intensity to 49% of that in the absence of PP. As pyrophosphate was hydrolyzed to two orthophosphate moieties by AP, the 580-nm fluorescence recovered in a time-dependent manner. By examining the initial slope of this time-dependent fluorescence recovery, we succeeded in evaluating the 50% inhibitory concentrations of orthovanadate toward two AP isozymes under near-physiological conditions. Full article

(This article belongs to the Special Issue State-of-the-Art Sensors Technology in Japan 2017)

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