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  • 1. Cippitelli, E.
    et al.
    Gasparrini, S.
    Gambi, E.
    Spinsante, S.
    Wåhslén, Jonas
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Orhan, Ibrahim
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Lindh, Thomas
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Time synchronization and data fusion for RGB-Depth cameras and inertial sensors in AAL applications2015In: 2015 IEEE International Conference on Communication Workshop, ICCW 2015, IEEE conference proceedings, 2015, p. 265-270Conference paper (Refereed)
    Abstract [en]

    Ambient Assisted Living applications often need to integrate data from multiple sensors, to provide consistent information on the observed phenomena. Data fusion based on samples from several sensors requires accurate time synchronization with sufficient resolution, depending on the sensor sampling frequency. This work presents a technical platform for the efficient and accurate synchronization of the data captured from RGB-Depth cameras and wearable inertial sensors, that can be integrated in AAL solutions. A case study of sensor data fusion for Timed Up and Go test is also presented and discussed.

  • 2. Gasparrini, S.
    et al.
    Cippitelli, E.
    Gambi, E.
    Spinsante, S.
    Wåhslén, Jonas
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Orhan, Ibrahim
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Lindh, Thomas
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Proposal and experimental evaluation of fall detection solution based on wearable and depth data fusion2016In: ICT Innovations 2015: Emerging Technologies For Better Living, Springer, 2016, Vol. 399, p. 99-108Conference paper (Refereed)
    Abstract [en]

    Fall injury issues represent a serious problem for elderly in our society. These people want to live in their home as long as possible and technology can improve their security and independence. In this work we study the joint use of a camera based system and wearable devices, in the so called data fusion approach, to design a fall detection solution. The synchronization issues between the heterogeneous data provided by the devices are properly treated, and three different fall detection algorithms are implemented. Experimental results are also provided, to compare the proposed solutions.

  • 3.
    Jacobsson, Martin
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Health Informatics and Logistics.
    Wåhslén, Jonas
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Health Informatics and Logistics.
    Virtual machine execution for wearables based on WebAssembly2018Conference paper (Refereed)
    Abstract [en]

    Today, the programming of a complete wearable sensor system requires writing code in different programming languages for the different parts of the systems, such as the wearable sensor platform itself, the gateway, the back-end server, and the client app. In this paper, we propose to use WebAssembly, which is a simple but powerful virtual machine standard already supported by all major web browsers. We show that it is possible to implement a WebAssembly interpreter for embedded systems, such as the Texas Instruments CC2652R system-on-chip and this enables the same code to execute in all parts of the systems. In our proof-of-concept implementation, we use Bluetooth low energy, which means that smartphones can communicate with and program our device without the need for special hardware.

  • 4.
    Wåhslén, Jonas
    KTH, School of Technology and Health (STH), Data- och elektroteknik.
    Multi-Sensor Data Synchronization using Mobile Phones2013Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Body sensor networking is a rapidly growing technology. Today wearable sensors are used to measure and monitor e.g. pulse, temperature, skin conductance, heart activity, and movement (through GPS or inertial measurement units). Mobile phones can act as coordinating nodes in wireless personal area networks used in home automation, healthcare, sport and wellness e.g. to measure pulse and distance. Integration of data from multiple sources sensors (data fusion) means that data from each sensor node needs to be associated with data from other sensor nodes sampled at approximately the same time. Accurate methods for time synchronization are therefore a necessary prerequisite for reliable data fusion.

    This thesis studies time synchronization problems in Bluetooth piconets between multiple wireless sensor nodes connected to a mobile phone that acts as coordinating node. Three different algorithms to enable correct data fusion have been developed, implemented and evaluated. The first is a single clock solution that synchronizes multiple wireless sensor nodes based solely on the mobile phone’s clock. The other two algorithms synchronize the clocks in sensor nodes to the clock in the coordinating node. 

  • 5.
    Wåhslén, Jonas
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Health Informatics and Logistics.
    Technical Solutions for Internet-based Wireless Sensor Networks in e-Health Applications2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    E-Health technology has developed rapidly in the last decade. Body-worn sen- sors have developed from an idea to a reality. Today, wireless sensors can perform functions from measuring heartbeats to advanced motion recognition. However, the integration of the various available solutions is still lacking. The research presented in this thesis examined important issues in wireless sensor networks and mobile phone systems for e-Health applications. The dissertation covers four essential areas for successful integration of IoT communication systems for e-Health. The first area is fusion of sensor data. In the previous licentiate thesis (2013), three algo- rithms were developed to synchronise data from multiple wireless sensors. The dissertation presents a method to merge data from wireless sensors with video streams. That was subsequently applied for automatic fall prevention and fall detec- tion using inertial sensors and a depth camera. The second area is mobile phone centric systems for Wi-Fi device-to-device sensor communication enabling mobility in ambient assisted living (AAL) services. The third area is a real-time monitoring and control system for Bluetooth wireless communication networks. Lastly, the dissertation presents a software framework to iteratively develop, tune and deploy functions in wireless sensor network using dynamic software updating.

  • 6.
    Wåhslén, Jonas
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Health Informatics and Logistics.
    Lindh, Thomas
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Health Informatics and Logistics.
    A Javascript Web Framework for Rapid Development of Applications in IoT System for eHealthManuscript (preprint) (Other academic)
    Abstract [en]

    Bluetooth Low Energy (BLE) is currently the dom- inating wireless network solution for eHealth and sports. Howev- er, most BLE sensors require dedicated applications with limited development capabilities. This paper presents a method for rapid development of applications in distributed BLE IoT systems for eHealth and sports. The method is implemented as a JavaScript web framework based on HTML5 canvas, WebSocket and Web Bluetooth APIs. This paper demonstrates how the framework can be applied to develop an application for monitoring physical activity and heart rate. The framework enables software and service operators to iteratively create, tune and deploy filter algorithms in distributed BLE IoT systems, without rebooting nodes or restarting programs using dynamic software updating.

  • 7.
    Wåhslén, Jonas
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Biomedical Engineering and Health Systems, Health Informatics and Logistics.
    Lindh, Thomas
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    A javascript web framework for rapid development of applications in IoT systems for eHealth2018In: 2018 IEEE 20th International Conference on e-Health Networking, Applications and Services, Healthcom 2018, Institute of Electrical and Electronics Engineers Inc. , 2018Conference paper (Refereed)
    Abstract [en]

    Bluetooth Low Energy (BLE) is currently the dominating wireless network solution for eHealth and sports. However, most BLE sensors require dedicated applications with limited development capabilities. This paper presents a method for rapid development of applications in distributed BLE IoT systems for eHealth and sports. The method is implemented as a JavaScript web framework based on HTML5 canvas, WebSocket and Web Bluetooth APIs. This paper demonstrates how the framework can be applied to develop an application for monitoring physical activity and heart rate. The framework enables software and service operators to iteratively create, tune and deploy filter algorithms in distributed BLE IoT systems, without rebooting nodes or restarting programs using dynamic software updating.

  • 8.
    Wåhslén, Jonas
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Lindh, Thomas
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Real-time Performance Management of Assisted Living Services for Bluetooth Low Energy Sensor Communication2017In: Integrated Network and Service Management (IM), 2017 IFIP/IEEE Symposium on, IEEE conference proceedings, 2017Conference paper (Refereed)
    Abstract [en]

    PerfMon is a prototype implementation of a realtime performance management method for sensor data communication in assisted living applications. It is implemented in accordance with the specification for GATT services in Bluetooth low energy (BLE). PerfMon provides a tool for real-time performance monitoring and control for caregivers and service providers. Test results from monitoring and control of packet loss ratio related to alarm thresholds are presented. PerfMon is adapted to cloud-based web services using RESTful APIs and established object models. Performance management is a necessary component in an overall management system of IoT devices for healthcare and assisted living applications.

  • 9.
    Wåhslén, Jonas
    et al.
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Lindh, Thomas
    KTH, School of Technology and Health (STH), Medical Engineering, Computer and Electronic Engineering.
    Smartphone-Centric Wi-Fi Device-to-Device Sensor Communication for User Mobility in AAL Services2016In: Personal, Indoor, and Mobile Radio Communications (PIMRC), 2016 IEEE 27th Annual International Symposium on, IEEE conference proceedings, 2016, p. 80-85Conference paper (Refereed)
    Abstract [en]

    This paper evaluates a use-case for smartphone-centric Wi-Fi device-to-device sensor communication that enables user mobility in ambient assisted living (AAL) services. A real-time performance measurement method has been developed and implemented to evaluate the smartphone’s ability to act as a hub and gateway for Wi-Fi connected sensor nodes. The results show that Wi-Fi Direct and Wi-Fi Hotspot are feasible solutions for smartphone-centric device-to-device communication that enables user mobility. In addition, a cloud-based web application for monitoring and displaying sensor data has been implemented.

  • 10.
    Wåhslén, Jonas
    et al.
    KTH, School of Technology and Health (STH), Data- och elektroteknik (Closed 20130701).
    Lindh, Thomas
    KTH, School of Technology and Health (STH), Data- och elektroteknik (Closed 20130701).
    Eriksson, Martin
    KTH, School of Technology and Health (STH).
    A novel approach to multi-sensor data synchronization using mobile phones2011In: Proceedings of the 5th International ICST Conference on Body Area Networks: BodyNets 2010, 2011, p. 171-174Conference paper (Refereed)
    Abstract [en]

    This paper presents a new algorithm for synchronization of data from multiple sensors arriving to a mobile phone's Bluetooth interface with possibly unknown and different sampling frequencies. A system that provides feedback signals to an athlete is one example where it is crucial to synchronize data from several wireless sensors; especially sensor nodes use different and unknown sampling rates.

  • 11.
    Wåhslén, Jonas
    et al.
    KTH, School of Technology and Health (STH), Data- och elektroteknik (Closed 20130701).
    Orhan, Ibrahim
    KTH, School of Technology and Health (STH), Data- och elektroteknik (Closed 20130701).
    Lindh, Thomas
    KTH, School of Technology and Health (STH).
    Local Time Synchronization in Bluetooth Piconets for Data Fusion Using Mobile Phones2011In: BSN 2011: 8th International Conference on Body Sensor Networks, 2011, p. 113-138Conference paper (Refereed)
    Abstract [en]

    This paper presents a method to synchronize the clocks in a Bluetooth piconet from the application layer in a mobile phone. It adapts algorithms for time synchronization of distributed systems and the Internet to Bluetooth networks. The performance issues that cause problems for data synchronization between master and slaves in Bluetooth are highlighted. The tests show that the synchronization error is limited to one sampling time.

  • 12.
    Wåhslén, Jonas
    et al.
    KTH, School of Technology and Health (STH), Data- och elektroteknik (Closed 20130701).
    Orhan, Ibrahim
    KTH, School of Technology and Health (STH), Data- och elektroteknik (Closed 20130701).
    Lindh, Thomas
    KTH, School of Technology and Health (STH), Data- och elektroteknik (Closed 20130701).
    Eriksson, Martin
    KTH, School of Technology and Health (STH), Medical sensors, signals and systems (MSSS) (Closed 20130701).
    A novel approach to multi-sensor data synchronisation using mobile phones2013In: International Journal of Autonomous and Adaptive Communications Systems, ISSN 1754-8632, E-ISSN 1754-8640, Vol. 6, no 3, p. 289-303Article in journal (Refereed)
    Abstract [en]

    This paper presents a new algorithm for application layer synchronisation of data from multiple sensors arriving to a mobile phone's Bluetooth interface. A system that provides feedback signals to an athlete is one example where it is crucial to synchronise data from several wireless sensors. This paper also discusses synchronisation problems caused by unpredictable Bluetooth transmission performance. 

  • 13.
    Wåhslén, Jonas
    et al.
    KTH, School of Technology and Health (STH), Data- och elektroteknik (Closed 20130701).
    Orhan, Ibrahim
    KTH, School of Technology and Health (STH), Data- och elektroteknik (Closed 20130701).
    Sturm, Dennis
    KTH, School of Technology and Health (STH), Centres, Centre for Technology in Medicine and Health, CTMH.
    Lindh, Thomas
    KTH, School of Technology and Health (STH), Data- och elektroteknik (Closed 20130701).
    Performance evaluation of time synchronization and clock drift compensation in wireless personal area networks2012In: BodyNets '12 Proceedings of the 7th International Conference on Body Area Networks, ICST , 2012, p. 153-158Conference paper (Refereed)
    Abstract [en]

    Efficient algorithms for time synchronization, including compensation for clock drift, are essential in order to obtain reliable fusion of data samples from multiple wireless sensor nodes. This paper evaluates the performance of algorithms based on three different approaches; one that synchronizes the local clocks on the sensor nodes, and a second that uses a single clock on the receiving node (e.g. a mobile phone), and a third that uses broadcast messages. The performances of the synchronization algorithms are evaluated in wireless personal area networks, especially Bluetooth piconets and ZigBee/IEEE 802.15.4 networks. A new approach for compensation of clock drift and a realtime implementation of single node synchronization from the mobile phone are presented and tested. Finally, applications of data fusion and time synchronization are shown in two different use cases; a kayaking sports case, and monitoring of heart and respiration of prematurely born infants. 

  • 14.
    Wåhslén, Jonas
    et al.
    KTH, School of Technology and Health (STH), Data- och elektroteknik (Closed 20130701).
    Sturm, Dennis
    KTH, School of Technology and Health (STH), Centres, Centre for Technology in Medicine and Health, CTMH.
    ExecutiveSummary of AugmentIT: A Smart Phone App that generates kinematic feedback based on augmented reality data e.g. vidoeo and IMU (or other sensor) data2012Other (Other (popular science, discussion, etc.))
1 - 14 of 14
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