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Open AccessArticle Perspective Preserving Solution for Quasi-Orthoscopic Video See-Through HMDs

by Fabrizio Cutolo, Umberto Fontana and Vincenzo Ferrari

Technologies 2018, 6(1), 9; doi:10.3390/technologies6010009

Received: 18 December 2017 / Revised: 9 January 2018 / Accepted: 10 January 2018 / Published: 13 January 2018

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Abstract

In non-orthoscopic video see-through (VST) head-mounted displays (HMDs), depth perception through stereopsis is adversely affected by sources of spatial perception errors. Solutions for parallax-free and orthoscopic VST HMDs were considered to ensure proper space perception but at expenses of an increased bulkiness and

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In non-orthoscopic video see-through (VST) head-mounted displays (HMDs), depth perception through stereopsis is adversely affected by sources of spatial perception errors. Solutions for parallax-free and orthoscopic VST HMDs were considered to ensure proper space perception but at expenses of an increased bulkiness and weight. In this work, we present a hybrid video-optical see-through HMD the geometry of which explicitly violates the rigorous conditions of orthostereoscopy. For properly recovering natural stereo fusion of the scene within the personal space in a region around a predefined distance from the observer, we partially resolve the eye-camera parallax by warping the camera images through a perspective preserving homography that accounts for the geometry of the VST HMD and refers to such distance. For validating our solution; we conducted objective and subjective tests. The goal of the tests was to assess the efficacy of our solution in recovering natural depth perception in the space around said reference distance. The results obtained showed that the quasi-orthoscopic setting of the HMD; together with the perspective preserving image warping; allow the recovering of a correct perception of the relative depths. The perceived distortion of space around the reference plane proved to be not as severe as predicted by the mathematical models. Full article

(This article belongs to the Special Issue Wearable Technologies)

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Open AccessFeature PaperArticle Dynamic Gesture Recognition Using a Smart Glove in Hand-Assisted Laparoscopic Surgery

by Lidia Santos, Nicola Carbonaro, Alessandro Tognetti, José Luis González, Eusebio de la Fuente, Juan Carlos Fraile and Javier Pérez-Turiel

Technologies 2018, 6(1), 8; doi:10.3390/technologies6010008

Received: 14 November 2017 / Revised: 10 January 2018 / Accepted: 10 January 2018 / Published: 13 January 2018

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Abstract

This paper presents a methodology for movement recognition in hand-assisted laparoscopic surgery using a textile-based sensing glove. The aim is to recognize the commands given by the surgeon’s hand inside the patient’s abdominal cavity in order to guide a collaborative robot. The glove,

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This paper presents a methodology for movement recognition in hand-assisted laparoscopic surgery using a textile-based sensing glove. The aim is to recognize the commands given by the surgeon’s hand inside the patient’s abdominal cavity in order to guide a collaborative robot. The glove, which incorporates piezoresistive sensors, continuously captures the degree of flexion of the surgeon’s fingers. These data are analyzed throughout the surgical operation using an algorithm that detects and recognizes some defined movements as commands for the collaborative robot. However, hand movement recognition is not an easy task, because of the high variability in the motion patterns of different people and situations. The data detected by the sensing glove are analyzed using the following methodology. First, the patterns of the different selected movements are defined. Then, the parameters of the movements for each person are extracted. The parameters concerning bending speed and execution time of the movements are modeled in a prephase, in which all of the necessary information is extracted for subsequent detection during the execution of the motion. The results obtained with 10 different volunteers show a high degree of precision and recall. Full article

(This article belongs to the Special Issue Wearable Technologies)

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Open AccessArticle A Low-Cost, Wearable Opto-Inertial 6-DOF Hand Pose Tracking System for VR

by Andualem T. Maereg, Emanuele L. Secco, Tayachew F. Agidew, David Reid and Atulya K. Nagar

Technologies 2017, 5(3), 49; doi:10.3390/technologies5030049

Received: 31 May 2017 / Revised: 22 July 2017 / Accepted: 25 July 2017 / Published: 28 July 2017

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Abstract

In this paper, a low cost, wearable six Degree of Freedom (6-DOF) hand pose tracking system is proposed for Virtual Reality applications. It is designed for use with an integrated hand exoskeleton system for kinesthetic haptic feedback. The tracking system consists of an

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In this paper, a low cost, wearable six Degree of Freedom (6-DOF) hand pose tracking system is proposed for Virtual Reality applications. It is designed for use with an integrated hand exoskeleton system for kinesthetic haptic feedback. The tracking system consists of an Infrared (IR) based optical tracker with low cost mono-camera and inertial and magnetic measurement unit. Image processing is done on LabVIEW software to extract the 3-DOF position from two IR targets and Magdwick filter has been implemented on Mbed LPC1768 board to obtain orientation data. Six DOF hand tracking outputs filtered and synchronized on LabVIEW software are then sent to the Unity Virtual environment via User Datagram Protocol (UDP) stream. Experimental results show that this low cost and compact system has a comparable performance of minimal Jitter with position and orientation Root Mean Square Error (RMSE) of less than 0.2 mm and 0.15 degrees, respectively. Total Latency of the system is also less than 40 ms. Full article

(This article belongs to the Special Issue Wearable Technologies)

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Open AccessArticle Development of a High-Speed Current Injection and Voltage Measurement System for Electrical Impedance Tomography-Based Stretchable Sensors

by Stefania Russo, Samia Nefti-Meziani, Nicola Carbonaro and Alessandro Tognetti

Technologies 2017, 5(3), 48; doi:10.3390/technologies5030048

Received: 12 July 2017 / Revised: 20 July 2017 / Accepted: 21 July 2017 / Published: 26 July 2017

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Abstract

Electrical impedance tomography (EIT) is an imaging method that can be applied over stretchable conductive-fabric materials to realize soft and wearable pressure sensors through current injections and voltage measurements at electrodes placed at the boundary of a conductive medium. In common EIT systems,

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Electrical impedance tomography (EIT) is an imaging method that can be applied over stretchable conductive-fabric materials to realize soft and wearable pressure sensors through current injections and voltage measurements at electrodes placed at the boundary of a conductive medium. In common EIT systems, the voltage data are serially measured by means of multiplexers, and are hence collected at slightly different times, which affects the real-time performance of the system. They also tend to have complicated hardware, which increases power consumption. In this paper, we present our design of a 16-electrode high-speed EIT system that simultaneously implements constant current injection and differential potential measurements. This leads to a faster, simpler-to-implement and less-noisy technique, when compared with traditional EIT approaches. Our system consists of a Howland current pump with two multiplexers for a constant DC current supply, and a data acquisition card. It guarantees a data collection rate of 78 frames/s. The results from our conductive stretchable fabric sensor show that the system successfully performs voltage data collection with a mean signal-to-noise ratio (SNR) of 55 dB, and a mean absolute deviation (MAD) of 0.5 mV. The power consumption can be brought down to 3 mW; therefore, it is suitable for battery-powered applications. Finally, pressure contacts over the sensor are properly reconstructed, thereby validating the efficiency of our EIT system for soft and stretchable sensor applications. Full article

(This article belongs to the Special Issue Wearable Technologies)

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Open AccessArticle Determining the Reliability of Several Consumer-Based Physical Activity Monitors

by Joshua M. Bock, Leonard A. Kaminsky, Matthew P. Harber and Alexander H. K. Montoye

Technologies 2017, 5(3), 47; doi:10.3390/technologies5030047

Received: 31 May 2017 / Revised: 19 July 2017 / Accepted: 21 July 2017 / Published: 24 July 2017

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Abstract

Limited research exists on the reliability of consumer-based physical activity monitors (CPAMs) despite numerous studies on their validity. Consumers often purchase CPAMs to assess their physical activity (PA) habits over time, emphasizing CPAM reliability more so than their validity; therefore, the purpose of

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Limited research exists on the reliability of consumer-based physical activity monitors (CPAMs) despite numerous studies on their validity. Consumers often purchase CPAMs to assess their physical activity (PA) habits over time, emphasizing CPAM reliability more so than their validity; therefore, the purpose of this study was to investigate the reliability of several CPAMs. In this study, 30 participants wore a pair of four CPAM models (Fitbit One, Zip, Flex, and Jawbone Up24) for a total of eight monitors, while completing seven activities in the laboratory. Activities were completed in two consecutive five-minute bouts. Participants then wore either all wrist- or hip-mounted CPAMs in a free-living setting for the remainder of the day. Intra-monitor reliability for steps (0.88–0.99) was higher than kcals (0.77–0.94), and was higher for hip-worn CPAMs than for wrist-worn CPAMs (p < 0.001 for both). Inter-monitor reliability in the laboratory for steps (0.81–0.99) was higher than kcals (0.64–0.91) and higher for hip-worn CPAMs than for wrist-worn CPAMs (p < 0.001 for both). Free-living correlations were 0.61–0.98, 0.35–0.96, and 0.97–0.98 for steps, kcals, and active minutes, respectively. These findings illustrate that all CPAMs assessed yield reliable estimations of PA. Additionally, all CPAMs tested can provide reliable estimations of physical activity within the laboratory but appear less reliable in a free-living setting. Full article

(This article belongs to the Special Issue Wearable Technologies)

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Open AccessArticle Communication Challenges in on-Body and Body-to-Body Wearable Wireless Networks—A Connectivity Perspective

by Dhafer Ben Arbia, Muhammad Mahtab Alam, Yannick Le Moullec and Elyes Ben Hamida

Technologies 2017, 5(3), 43; doi:10.3390/technologies5030043

Received: 15 May 2017 / Revised: 29 June 2017 / Accepted: 30 June 2017 / Published: 6 July 2017

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Abstract

Wearable wireless networks (WWNs) offer innovative ways to connect humans and/or objects anywhere, anytime, within an infinite variety of applications. WWNs include three levels of communications: on-body, body-to-body and off-body communication. Successful communication in on-body and body-to-body networks is often challenging due to

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Wearable wireless networks (WWNs) offer innovative ways to connect humans and/or objects anywhere, anytime, within an infinite variety of applications. WWNs include three levels of communications: on-body, body-to-body and off-body communication. Successful communication in on-body and body-to-body networks is often challenging due to ultra-low power consumption, processing and storage capabilities, which have a significant impact on the achievable throughput and packet reception ratio as well as latency. Consequently, all these factors make it difficult to opt for an appropriate technology to optimize communication performance, which predominantly depends on the given application. In particular, this work emphasizes the impact of coarse-grain factors (such as dynamic and diverse mobility, radio-link and signal propagation, interference management, data dissemination schemes, and routing approaches) directly affecting the communication performance in WWNs. Experiments have been performed on a real testbed to investigate the connectivity behavior on two wireless communication levels: on-body and body-to-body. It is concluded that by considering the impact of above-mentioned factors, the general perception of using specific technologies may not be correct. Indeed, for on-body communication, by using the IEEE 802.15.6 standard (which is specifically designed for on-body communication), it is observed that while operating at low transmission power under realistic conditions, the connectivity can be significantly low, thus, the transmission power has to be tuned carefully. Similarly, for body-to-body communication in an indoor environment, WiFi IEEE 802.11n also has a high threshold of end-to-end disconnections beyond two hops (approximatively 25 m). Therefore, these facts promote the use of novel technologies such as 802.11ac, NarrowBand-IoT (NB-IoT) etc. as possible candidates for body-to-body communications as a part of the Internet of humans concept. Full article

(This article belongs to the Special Issue Wearable Technologies)

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Open AccessFeature PaperArticle Oxide Thin-Film Transistors on Fibers for Smart Textiles

by Niko Münzenrieder, Christian Vogt, Luisa Petti, Giovanni A. Salvatore, Giuseppe Cantarella, Lars Büthe and Gerhard Tröster

Technologies 2017, 5(2), 31; doi:10.3390/technologies5020031

Received: 30 April 2017 / Revised: 26 May 2017 / Accepted: 29 May 2017 / Published: 2 June 2017

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Abstract

Smart textiles promise to have a significant impact on future wearable devices. Among the different approaches to combine electronic functionality and fabrics, the fabrication of active fibers results in the most unobtrusive integration and optimal compatibility between electronics and textile manufacturing equipment. The

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Smart textiles promise to have a significant impact on future wearable devices. Among the different approaches to combine electronic functionality and fabrics, the fabrication of active fibers results in the most unobtrusive integration and optimal compatibility between electronics and textile manufacturing equipment. The fabrication of electronic devices, in particular transistors on heavily curved, temperature sensitive, and rough textiles fibers is not easily achievable using standard clean room technologies. Hence, we evaluated different fabrication techniques and multiple fibers made from polymers, cotton, metal and glass exhibiting diameters down to 125 μm. The benchmarked techniques include the direct fabrication of thin-film structures using a low temperature shadow mask process, and the transfer of thin-film transistors (TFTs) fabricated on a thin (≈1 μm) flexible polymer membrane. Both approaches enable the fabrication of working devices, in particular the transfer method results in fully functional transistor fibers, with an on-off current ratio >

10^{7}

, a threshold voltage of ≈0.8

V

, and a field effect mobility exceeding 7

c m^{2} V^{- 1} s^{- 1}

. Finally, the most promising fabrication approach is used to integrate a commercial nylon fiber functionalized with InGaZnO TFTs into a woven textile. Full article

(This article belongs to the Special Issue Wearable Technologies)

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Review

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Open AccessReview Cuff-Less and Continuous Blood Pressure Monitoring: A Methodological Review

by Manuja Sharma, Karinne Barbosa, Victor Ho, Devon Griggs, Tadesse Ghirmai, Sandeep K. Krishnan, Tzung K. Hsiai, Jung-Chih Chiao and Hung Cao

Technologies 2017, 5(2), 21; doi:10.3390/technologies5020021

Received: 5 March 2017 / Revised: 27 April 2017 / Accepted: 5 May 2017 / Published: 9 May 2017

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Abstract

Blood pressure (BP) is one of the most important monitoring parameters in clinical medicine. For years, the cuff-based sphygmomanometer and the arterial invasive line have been the gold standards for care professionals to assess BP. During the past few decades, the wide spread

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Blood pressure (BP) is one of the most important monitoring parameters in clinical medicine. For years, the cuff-based sphygmomanometer and the arterial invasive line have been the gold standards for care professionals to assess BP. During the past few decades, the wide spread of the oscillometry-based BP arm or wrist cuffs have made home-based BP assessment more convenient and accessible. However, the discontinuous nature, the inability to interface with mobile applications, the relative inaccuracy with movement, and the need for calibration have rendered those BP oscillometry devices inadequate for next-generation healthcare infrastructure where integration and continuous data acquisition and communication are required. Recently, the indirect approach to obtain BP values has been intensively investigated, where BP is mathematically derived through the “Time Delay” in propagation of pressure waves in the vascular system. This holds promise for the realization of cuffless and continuous BP monitoring systems, for both patients and healthy populations in both inpatient and outpatient settings. This review highlights recent efforts in developing these next-generation blood pressure monitoring devices and compares various mathematical models. The unmet challenges and further developments that are crucial to develop “Time Delay”-based BP devices are also discussed. Full article

(This article belongs to the Special Issue Wearable Technologies)

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Review

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Guest Editor Dr. Nicola Carbonaro Research Center "E. Piaggio”, University of Pisa, Largo L. Lazzerino, 1, 56122 Pisa, Italy Website \| E-Mail Interests: biomedical engineering, wearable sensing system, biomechanics, biomedical sensors and technologies, physiological sensors, rehabilitation, wearable sensor design
Guest Editor Dr. Alessandro Tognetti Research Center "E. Piaggio” and Information Engineering Department, University of Pisa, Via G. Caruso 16, 56122 Pisa, Italy Website \| E-Mail Interests: biomedical engineering, biomedical sensing technologies, biomedical instrumentation, motion capture, data fusion, biomechanics, rehabilitation, wearable sensors and technologies