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Ivanov, Ivelin; Kuijper, Arjan [Advisor]; Wilmsdorff, Julian von [Advisor]; Kirchbuchner, Florian [Advisor]

CapBed - Preventive Assistance System for the Bed Area Based on Capacitive Sensing

2018

Darmstadt, TU, Master Thesis, 2018

Over the past decades, human activity recognition systems have become a major input modality for building automation. However, those systems also found recent applications in emergency detection, such as recognizing patient activities that may lead to life-threatening situations like falls or heart attacks. The aim of this thesis is to develop a sensor that recognizes whether a person wants to get out of bed. This is to prevent falls by illuminating the path or calling a nurse in time. In addition, such a system can also provide insights into the behavior of the user in the long term. Therefore, a concept of preventive assistance system for the bed area based on capacitive sensing is developed within the scope of this work. To this end, a comparison to other sensor technologies will be established, followed by a detailed overview of the technical background of capacitive proximity sensing. An innovative concept of a device that offers decent performance at an affordable price is proposed. Based on this concept a prototype system was developed and evaluated to investigate its sensing performance and identify possible limitations. As a future outlook, this thesis summarizes the occurred problems and suggests possible modifications that might improve the overall performance of the system.

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Wilmsdorff, Julian von; Kirchbuchner, Florian; Braun, Andreas; Kuijper, Arjan

Eliminating the Ground Reference for Wireless Electric Field Sensing

2018

Ambient Intelligence

European Conference on Ambient Intelligence (AmI) <14, 2018, Larnaca, Cyprus>

Capacitive systems are getting more and more attention these days. But many systems today like smart-phone screens, laptops, and non-mechanical buttons use capacitive techniques to measure events within several centimeters of distance. The reason that battery-powered devices don’t have high measurement ranges lies in the principle of capacitive measurement itself - the electrical ground is an inherent part of the measurement. In this paper, we present a method for passive and wireless capacitive systems to eliminate the reference to ground. This bears a couple of advantages for mobile, battery-powered capacitive sensor designs in the field of ambient intelligence. We compare the detection range of normal passive capacitive systems with our new approach. The results show that our improvements result in a higher detection range and higher power efficiency.

978-3-030-03061-2

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Kolf, Jan Niklas; Wilmsdorff, Julian von [Advisor]; Kuijper, Arjan [Advisor]

Evaluation of Activity of Daily Life Recognition based on Electric Field Tokens

2018

Darmstadt, TU, Bachelor Thesis, 2018

Electric field sensors are used in a variety of ways to recognize different human actions and behaviors, for example, fall detection or classification of movements. However, very little is known about the number of sensors that are needed to achieve an acceptable recognition rate. Most systems just use as many sensors as possible to achieve confusion matrices with high true positive and true negative rates. In this thesis, the relation of recognition rates and the size of a system composed of electric field sensors shall be further investigated. For this purpose, several setups to recognize different human activities will be created and evaluated, each with a varying number of sensor tokens.

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Fu, Biying; Kirchbuchner, Florian; Wilmsdorff, Julian von; Große-Puppendahl, Tobias; Braun, Andreas; Kuijper, Arjan

Performing Indoor Localization with Electric Potential Sensing

2018

Journal of Ambient Intelligence and Humanized Computing

Location-based services or smart home applications all depend on an accurate indoor positioning system. Basically one divides these systems into token-based and token-free localization systems. In this work, we focus on the token-free system based on smart floor technology. Smart floors can typically be built using pressure sensors or capacitive sensors. However, these set-ups are often hard to deploy as mechanical or electrical features are required below the surface and even harder to replace when detected a sensor malfunctioning. Therefore we present a novel indoor positioning system using an uncommon form of passive electric field sensing (EPS), which detects the electric potential variation caused by body movement. The EPS-based smart floor set-up is easy to install by deploying a grid of passive electrode wires underneath any non-conductive surfaces. Easy maintenance is also ensured by the fact that the sensors are not placed underneath the surface, but on the side. Due to the passive measuring nature, low power consumption is achieved as opposed to active capacitive measurement. Since we do not collect image data as in visual-based systems and all sensor data is processed locally, we preserve the user’s privacy. The proposed architecture achieves a high position accuracy and an excellent spatial resolution. Based on our evaluation conducted in our living lab, we measure a mean positioning error of only 12.7 cm.

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Rus, Silvia; Hammacher, Felix; Wilmsdorff, Julian von; Braun, Andreas; Große-Puppendahl, Tobias; Kirchbuchner, Florian; Kuijper, Arjan

Prototyping Shape-Sensing Fabrics Through Physical Simulation

2018

Ambient Intelligence

European Conference on Ambient Intelligence (AmI) <14, 2018, Larnaca, Cyprus>

Lecture Notes in Computer Science (LNCS), 11249

Embedding sensors into fabrics can leverage substantial improvements in application areas like working safety, 3D modeling or health-care, for example to recognize the risk of developing skin ulcers. Finding a suitable setup and sensor combination for a shape-sensing fabric currently relies on the intuition of an application engineer. We introduce a novel approach: Simulating the shape-sensing fabric first and optimize the design to achieve better real-world implementations. In order to enable developers to easily prototype their shape-sensing scenario, we have implemented a framework that enables soft body simulation and virtual prototyping. To evaluate our approach, we investigate the design of a system detecting sleeping postures. We simulate potential designs first, and implement a bed cover consisting of 40 distributed acceleration sensors. The validity of our framework is confirmed by comparing the simulated and real evaluation results. We show that both approaches achieve similar performances, with an F-measure of 85% for the virtual prototype and 89% for the real-world implementation.

978-3-030-03061-2

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Scherf, Lisa; Kirchbuchner, Florian; Wilmsdorff, Julian von; Fu, Biying; Braun, Andreas; Kuijper, Arjan

Step by Step: Early Detection of Diseases Using an Intelligent Floor

2018

Ambient Intelligence

European Conference on Ambient Intelligence (AmI) <14, 2018, Larnaca, Cyprus>

Lecture Notes in Computer Science (LNCS), 11249

The development of sensor technologies in smart homes helps to increase user comfort or to create safety through the recognition of emergency situations. For example, lighting in the home can be controlled or an emergency call can be triggered if sensors hidden in the floor detect a fall of a person. It makes sense to also use these technologies regarding prevention and early detection of diseases. By detecting deviations and behavioral changes through long-term monitoring of daily life activities it is possible to identify physical or cognitive diseases. In this work, we first examine in detail the existing possibilities to recognize the activities of daily life and the capability of such a system to conclude from the given data on illnesses. Then we propose a model for the use of floor-based sensor technology to help diagnose diseases and behavioral changes by analyzing the time spent in bed as well as the walking speed of users. Finally, we show that the system can be used in a real environment.

978-3-030-03061-2

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Wilmsdorff, Julian von; Kirchbuchner, Florian; Fu, Biying; Braun, Andreas; Kuijper, Arjan

An Exploratory Study on Electric Field Sensing

2017

Ambient Intelligence

European Conference on Ambient Intelligence (AmI) <13, 2017, Malaga, Spain>

Electric fields are influenced by the human body and other conducting materials. Capacitive measurement techniques are used in touch-screens, in the automobile industry, and for presence and activity recognition in Ubiquitous Computing. However, a drawback of the capacitive technology is the energy consumption, which is an important aspect for mobile devices. In this paper we explore possible applications of electric field sensing, a purely passive capacitive measurement technique, which can be implemented with an extremely low power consumption. To cover a wide range of applications, we examine five possible use cases in more detail. The results show that the application is feasible both in interior spaces and outdoors. Moreover, due to the low energy consumption, mobile usage is also possible.

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Fu, Biying; Kirchbuchner, Florian; Wilmsdorff, Julian von; Große-Puppendahl, Tobias; Braun, Andreas; Kuijper, Arjan

Indoor Localization Based on Passive Electric Field Sensing

2017

Ambient Intelligence

European Conference on Ambient Intelligence (AmI) <13, 2017, Malaga, Spain>

The ability to perform accurate indoor positioning opens a wide range of opportunities, including smart home applications and location-based services. Smart floors are a well-established technology to enable marker-free indoor localization within an instrumented environment. Typically, they are based on pressure sensors or varieties of capacitive sensing. These systems, however, are often hard to deploy as mechanical or electrical features are required below the surface. They might also have a limited range or not be compatible with different floor materials. In this paper, we present a novel indoor positioning system using an uncommon form of passive electric field sensing, which detects the change in body electric potential during movement. It is easy to install by deploying a grid of passive wires underneath any non-conductive floor surface. The proposed architecture achieves a high position accuracy and an excellent spatial resolution. In our evaluation, we measure a mean positioning error of only 12.7 cm. The proposed system also combines the advantages of very low power consumption, easy installation, easy maintenance, and the preservation of privacy.

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Kirchbuchner, Florian; Fu, Biying; Braun, Andreas; Wilmsdorff, Julian von

New Approaches for Localization and Activity Sensing in Smart Environments

2017

Ambient Assisted Living

Ambient Assisted Living (AAL) <9, 2016, Frankfurt, Germany>

Smart environments need to be able to fulfill the wishes of its occupants unobtrusively. To achieve this goal, it has to be guaranteed that the current state environment is perceived at all times. One of the most important aspects is to find the current position of the in- habitants and to perceive how they move in this environment. Numerous technologies enable such supervision. Particularly challenging are marker-free systems that are also privacy-preserving. In this paper, we present two such systems for localizing inhabitants in a Smart Environment using - electrical potential sensing and ultrasonic Doppler sensing. We present methods that infer location and track the user, based on the acquired sensor data. Finally, we discuss the advantages and challenges of these sensing technologies and provide an overview of future research directions.

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Wilmsdorff, Julian von; Kuijper, Arjan [Prüfer]; Große-Puppendahl, Tobias [Betreuer]

Activity Recognition based on Electric Potential Sensing

2015

Darmstadt, TU, Master Thesis, 2015

Electric fields are influenced by the human body and other conducting materials. This property can be used to detect presence of human bodies. For the detection of presence and activity recognition, mostly capacitive measurement techniques are used. Despite the fact that capacitive sensing is an fairly old technology, since it has been around since the 1920's, it is still a hot topic of ongoing research works. Today, capacitive measurement techniques are used in touch-screens, in the automobile industry and many other fields of Ubiquitous Computing. But a drawback of the capacitive technology is the energy consumption, which is an important aspect of mobile devices. That is why, in this thesis, i investigate the potential of electric potential sensing (EPS), a purely passive capacitive measurement technique, which can be implemented with an extremely low power consumption. First, the most commonly used capacitive measurement techniques will be analyzed and how they work. This is done to understand the pros and cons of electric potential sensing compared to other technologies. After analyzing electric potential sensing and related capacitive measurement techniques, we will have a closer look at some possible areas of application of electric potential sensing in an explorative studie. Hence, multiple experiments, involving electric potential sensing in various environmental settings for different use-case scenarios, will be conducted. This is done to evaluate the best use-case for this technology. Then, after selecting the most suitable use-case for activity recognition with EPS, two sensor systems are developed, discussed and evaluated. At the end, the benefits and limitations of EPS will be concluded with regards to capacitive sensing.

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Wilmsdorff, Julian von; Marinc, Alexander; Kuijper, Arjan

Context-Based Document Management in Smart Living Environments

2015

Distributed, Ambient, and Pervasive Interactions

International Conference on Distributed, Ambient and Pervasive Interactions (DAPI) <3, 2015, Los Angeles, CA, USA>

Nowadays an increasingly wide variety of multimedia devices can be networked together in ever-growing smart environments. Although these networks, thanks to mobile technology and Wi-Fi, are almost ubiquitous by now, the players therein are still working largely distinct from one another. To simply play a file on the playback device A, which is originally housed on device B, is therefore a complicated task, despite the theoretical possibility provided by existing networking. Especially playing and viewing files on multimedia devices under various circumstances and limited reproduction capabilities is a non-trivial problem. Current solutions from industry still put little interoperable approaches in proprietary systems. Individual multimedia devices of the same manufacturer can be combined intelligently, but with respect to the usability the system scales poorly, the (also physical) distribution increases the difficulty of access to the functions and control is largely independent of the user's context. In this work, a solution is developed, which focuses in particular on the context-based playback of files: sending video, music, image and text files to output devices with different display options, as well as the distribution of these multimedia files between devices. Activities are centered on a mobile device for visualizing the spatial distribution of all devices, including the user's position and the intuitive movement of files of various types between them.

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Große-Puppendahl, Tobias; Beck, Sebastian; Wilbers, Daniel; Zeiß, Steeven; Wilmsdorff, Julian von; Kuijper, Arjan

Ambient Gesture-Recognizing Surfaces with Visual Feedback

2014

Distributed, Ambient, and Pervasive Interactions

International Conference on Distributed, Ambient and Pervasive Interactions (DAPI) <2, 2014, Heraklion, Crete, Greece>

In recent years, gesture-based interaction gained increasing interest in Ambient Intelligence. Especially the success of camera-based gesture recognition systems shows that a great variety of applications can benefit significantly from natural and intuitive interaction paradigms. Besides camera-based systems, proximity-sensing surfaces are especially suitable as an input modality for intelligent environments. They can be installed ubiquitously under any kind of non-conductive surface, such as a table. However, interaction barriers and the types of supported gestures are often not apparent to the user. In order to solve this problem, we investigate an approach which combines a semi-transparent capacitive proximity-sensing surface with an LED array. The LED array is used to indicate possible gestural movements and provide visual feedback on the current interaction status. A user study shows that our approach can enhance the user experience, especially for inexperienced users.

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Große-Puppendahl, Tobias; Herber, Sebastian; Wimmer, Raphael; Englert, Frank; Beck, Sebastian; Wilmsdorff, Julian von; Wichert, Reiner; Kuijper, Arjan

Capacitive Near-Field Communication for Ubiquitous Interaction and Perception

2014

UbiComp' 14

International Conference on Ubiquitous Computing (Ubicomp) <16, 2014, Seattle, WA, USA>

Smart objects within instrumented environments offer an always available and intuitive way of interacting with a system. Connecting these objects to other objects in range or even to smartphones and computers, enables substantially innovative interaction and sensing approaches. In this paper, we investigate the concept of Capacitive Near-Field Communication to enable ubiquitous interaction with everyday objects in a short-range spatial context. Our central contribution is a generic framework describing and evaluating this communication method in Ubiquitous Computing. We prove the relevance of our approach by an open-source implementation of a low-cost object tag and a transceiver offering a high-quality communication link at typical distances up to 15 cm. Moreover, we present three case studies considering tangible interaction for the visually impaired, natural interaction with everyday objects, and sleeping behavior analysis.

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Wilmsdorff, Julian von; Marinc, Alexander [Betreuer]; Kuijper, Arjan [Gutachter]

Kontextbasiertes Dokumentenmanagement in intelligenten Wohnumgebungen

2012

Darmstadt, TU, Bachelor Thesis, 2012

Heutzutage werden vermehrt verschiedenste Multimediageräte miteinander in immer weiter wachsenden intelligenten Umgebungen vernetzt. Obwohl diese Netze heutzutage Dank mobiler Technik und WLAN fast omnipräsent sind, arbeiten die darin enthaltenen Abspielgeräte immer noch weitgehend distinkt voneinander. Das einfache Abspielen einer Datei auf dem Wiedergabegerät A, die ursprünglich auf Gerät B beherbergt wird, ist daher, trotz der theoretisch vorhandenen Möglichkeit durch die Vernetzung, eine komplizierte Aufgabe geworden. Besonders das Abspielen und Anzeigen von Dateien auf Multimediageräten mit verschiedenen, unter Umständen begrenzten Wiedergabefähigkeiten ist ein nicht triviales Problem. Aktuelle Lösungen aus der Industrie setzen hier momentan noch auf wenig interoperable Ansätze in proprietären Systemen. Einzelne Multimediageräte gleicher Hersteller lassen sich so zwar intelligent verbinden, gerade mit Hinsicht auf die Benutzbarkeit skaliert das System jedoch schlecht, die (auch physikalische) Verteilung erhöht die Schwierigkeit des Zugangs zu den Funktionen und die Steuerung ist weitgehend unabhängig vom Kontext des Benutzers. In dieser Arbeit wird daher eine Lösung entwickelt, deren Fokus insbesondere auf dem kontextbasierten Abspielen von Dateien liegt. Genauer auf dem Wiedergeben von Video-, Musik-, Bild- sowie Textdateien auf Ausgabegeräten mit unterschiedlichen Darstellungsmöglichkeiten, sowie der Verteilung dieser Multimediadateien zwischen den Geräten. Im Zentrum steht hierbei ein mobiles Gerät zur Visualisierung der räumlichen Verteilung aller Geräte unter Einbeziehung der Position des Benutzers und der intuitiven Verschiebung von Dateien verschiedener Typen zwischen diesen.

  • Capacitive sensor technology
  • Electric field sensor technology
  • Signal processing
  • IoT