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Pervasive Tables of Contents: 02040506070809101112

Proceedings of Pervasive 2006: International Conference on Pervasive Computing

Fullname:Pervasive 2006: Pervasive Computing, 4th International Conference
Editors:Kenneth P. Fishkin; Bernt Schiele; Paddy Nixon; Aaron J. Quigley
Location:Dublin, Ireland
Dates:2006-May-07 to 2006-May-10
Series:Lecture Notes in Computer Science 3968 Springer 2006
Standard No:ISBN 3-540-33894-2; hcibib: Pervasive06
Links:Online Proceedings
A Practical Approach to Recognizing Physical Activities BIBAFull-Text 1-16
  Jonathan Lester; Tanzeem Choudhury; Gaetano Borriello
We are developing a personal activity recognition system that is practical, reliable, and can be incorporated into a variety of health-care related applications ranging from personal fitness to elder care. To make our system appealing and useful, we require it to have the following properties: (i) data only from a single body location needed, and it is not required to be from the same point for every user; (ii) should work out of the box across individuals, with personalization only enhancing its recognition abilities; and (iii) should be effective even with a cost-sensitive subset of the sensors and data features. In this paper, we present an approach to building a system that exhibits these properties and provide evidence based on data for 8 different activities collected from 12 different subjects. Our results indicate that the system has an accuracy rate of approximately 90% while meeting our requirements. We are now developing a fully embedded version of our system based on a cell-phone platform augmented with a Bluetooth-connected sensor board.
Building Reliable Activity Models Using Hierarchical Shrinkage and Mined Ontology BIBAFull-Text 17-32
  Emmanuel Munguia Tapia; Tanzeem Choudhury; Matthai Philipose
Activity inference based on object use has received considerable recent attention. Such inference requires statistical models that map activities to the objects used in performing them. Proposed techniques for constructing these models (hand definition, learning from data, and web extraction) all share the problem of model incompleteness: it is difficult to either manually or automatically identify all the possible objects that may be used to perform an activity, or to accurately calculate the probability with which they will be used. In this paper, we show how to use auxiliary information, called an ontology, about the functional similarities between objects to mitigate the problem of model incompleteness. We show how to extract a large, relevant ontology automatically from WordNet, an online lexical reference system for the English language. We adapt a statistical smoothing technique, called shrinkage, to apply this similarity information to counter the incompleteness of our models. Our results highlight two advantages of performing shrinkage. First, overall activity recognition accuracy improves by 15.11% by including the ontology to re-estimate the parameters of models that are automatically mined from the web. Shrinkage can therefore serve as a technique for making web-mined activity models more attractive. Second, smoothing yields an increased recognition accuracy when objects not present in the incomplete models are used while performing an activity. When we replace 100% of the objects with other objects that are functionally similar, we get an accuracy drop of only 33% when using shrinkage as opposed to 91.66% (equivalent to random guessing) without shrinkage. If training data is available, shrinkage further improves classification accuracy.
"Need to Know": Examining Information Need in Location Discourse BIBAFull-Text 33-49
  Derek F. Reilly; David Dearman; Vicki Ha; Ian Smith; Kori Inkpen
Location discourse involves the active or passive sharing of location information between individuals. Related applications include mobile friend locators, and location-dependent messaging. Privacy issues pertaining to location disclosure have been considered in research and relevant design guidelines are emerging, however what location information a user actually "needs to know" has received little systematic analysis to date. In this paper we present results from a questionnaire study and a diary study considering location information need. We provide a classification of location discourse and the factors which impact location need, showing that seemingly small changes in a scenario can yield drastically different location information needs. Finally, we summarize trends that are of interest to designers of location discourse applications.
Collaborative Localization: Enhancing WiFi-Based Position Estimation with Neighborhood Links in Clusters BIBAFull-Text 50-66
  Li-Wei Chan; Ji-Rung Chiang; Yi-Chao Chen; Chia-nan Ke; Jane Yung-jen Hsu; Hao-Hua Chu
Location-aware services can benefit from accurate and reliable indoor location tracking. The widespread adoption of 802.11x wireless LAN as the network infrastructure creates the opportunity to deploy WiFi-based location services with few additional hardware costs. While recent research has demonstrated adequate performance, localization error increases significantly in crowded and dynamic situations due to electromagnetic interferences. This paper proposes collaborative localization as an approach to enhance position estimation by leveraging more accurate location information from nearby neighbors within the same cluster. The current implementation utilizes ZigBee radio as the neighbor-detection sensor. This paper introduces the basic model and algorithm for collaborative localization. We also report experiments to evaluate its performance under a variety of clustering scenarios. Our results have shown 28.2-56% accuracy improvement over the baseline system Ekahau, a commercial WiFi localization system.
Risks of Using AP Locations Discovered Through War Driving BIBAFull-Text 67-82
  Minkyong Kim; Jeffrey J. Fielding; David Kotz
Many pervasive-computing applications depend on knowledge of user location. Because most current location-sensing techniques work only either indoors or outdoors, researchers have started using 802.11 beacon frames from access points (APs) to provide broader coverage. To use 802.11 beacons, they need to know AP locations. Because the actual locations are often unavailable, they use estimated locations from war driving. But these estimated locations may be different from actual locations. In this paper, we analyzed the errors in these estimates and the effect of these errors on other applications that depend on them. We found that the estimated AP locations have a median error of 32 meters. We considered the error in tracking user positions both indoors and outdoors. Using actual AP locations, we could improve the accuracy as much as 70% for indoors and 59% for outdoors. We also analyzed the effect of using estimated AP locations in computing AP coverage range and estimating interference among APs. The coverage range appeared to be shorter and the interference appeared to be more severe than in reality.
Declarative Support for Sensor Data Cleaning BIBAFull-Text 83-100
  Shawn R. Jeffery; Gustavo Alonso; Michael J. Franklin; Wei Hong; Jennifer Widom
Pervasive applications rely on data captured from the physical world through sensor devices. Data provided by these devices, however, tend to be unreliable. The data must, therefore, be cleaned before an application can make use of them, leading to additional complexity for application development and deployment. Here we present Extensible Sensor stream Processing (ESP), a framework for building sensor data cleaning infrastructures for use in pervasive applications. ESP is designed as a pipeline using declarative cleaning mechanisms based on spatial and temporal characteristics of sensor data. We demonstrate ESP's effectiveness and ease of use through three real-world scenarios.
Detecting and Interpreting Muscle Activity with Wearable Force Sensors BIBAFull-Text 101-116
  Paul Lukowicz; Friedrich Hanser; Christoph Szubski; Wolfgang Schobersberger
In this paper we present a system for assessing muscle activity by using wearable force sensors placed on the muscle surface. Such sensors are very thin, power efficient and have also been demonstrated as pure textile devices, so that they can be easily integrated in such garments as elastic underwear or tight shorts/shirt. On the example upper-leg muscle we show how good signal quality can be reliably acquired under realistic conditions. We then show how information about general user context can be derived from the muscle activity signal. We first look at the modes of locomotion problem which is a well studied, benchmark-like problem in the community. We then demonstrate the correlation between the signals from our system and user fatigue. We conclude with a discussion of other types of information that can be derived from the muscle activity based on physiological considerations and example data form our experiments.
The Design of a Portable Kit of Wireless Sensors for Naturalistic Data Collection BIBAFull-Text 117-134
  Emmanuel Munguia Tapia; Stephen S. Intille; Louis Lopez; Kent Larson
In this paper, we introduce MITes, a flexible kit of wireless sensing devices for pervasive computing research in natural settings. The sensors have been optimized for ease of use, ease of installation, affordability, and robustness to environmental conditions in complex spaces such as homes. The kit includes six environmental sensors: movement, movement tuned for object-usage-detection, light, temperature, proximity, and current sensing in electric appliances. The kit also includes five wearable sensors: onbody acceleration, heart rate, ultra-violet radiation exposure, RFID reader wristband, and location beacons. The sensors can be used simultaneously with a single receiver in the same environment. This paper describes our design goals and results of the evaluation of some of the sensors and their performance characteristics. Also described is how the kit is being used for acquisition of data in non-laboratory settings where real-time multi-modal sensor information is acquired simultaneously from several sensors worn on the body and up to several hundred sensors distributed in an environment.
The Smart Tachograph -- Individual Accounting of Traffic Costs and Its Implications BIBAFull-Text 135-152
  Vlad Coroama
Today, several costs caused by road traffic may either be only roughly approximated, or cannot be clearly assigned to the drivers causing them, or both. They are typically distributed evenly among a large fraction of drivers, which is both unfair and economically inefficient. We have built a prototypical platform, called the "Smart Tachograph", that allows us to measure traffic-related costs on an individual basis, thus supporting a more fine-granular charging of the responsible parties. Sensors observe the manner and circumstances in which a vehicle is driven, while several accounting authorities can evaluate this information and charge motorists on a pay-per-use basis. The Smart Tachograph offers valuable insights for the deployment of future ubiquitous computing services in general: its implementation has obvious requirements in terms of security and privacy; its deployment model is realistic through the strong economic incentives it offers; and its usage directly affects core societal values such as fairness and trust. This paper summarizes our design considerations and discusses the feasibility and wider economic and societal implications of fielding such a system.
Domino: Exploring Mobile Collaborative Software Adaptation BIBAFull-Text 153-168
  Marek Bell; Malcolm Hall; Matthew Chalmers; Philip D. Gray; Barry Brown
Social Proximity Applications (SPAs) are a promising new area for ubicomp software that exploits the everyday changes in the proximity of mobile users. While a number of applications facilitate simple file sharing between co -- present users, this paper explores opportunities for recommending and sharing software between users. We describe an architecture that allows the recommendation of new system components from systems with similar histories of use. Software components and usage histories are exchanged between mobile users who are in proximity with each other. We apply this architecture in a mobile strategy game in which players adapt and upgrade their game using components from other players, progressing through the game through sharing tools and history. More broadly, we discuss the general application of this technique as well as the security and privacy challenges to such an approach.
Keep Your Eyes on the Road and Your Finger on the Trigger -- Designing for Mixed Focus of Attention in a Mobile Game for Brief Encounters BIBAFull-Text 169-186
  Liselott Brunnberg; Oskar Juhlin
In this paper we present an initial user feedback study of the Road Rager prototype. Road Rager is a mixed reality game, designed to enable passengers in different cars to play against each other during an encounter in traffic. We are concerned with how to design a game which balances the player's focus of attention between traffic and the computer interfaces, to provide a game which is comprehensive, interesting and challenging during a very limited lifetime. The study shows that a tangible user interface enables the player to handle the interaction in the game while watching for cars in the vicinity. Further, the users found multiplayer gaming during brief encounters exciting. However, the study also showed that minimalism is critical to the design. The gestures should preferably be indexical rather than symbolic, and elaborate forms of identification as a condition for manipulative success should be avoided. Finally, tangible user interfaces also allow a type of gaming where players only focus on the computers' interface, which suppresses the experience of combining traffic interaction with computer interaction.
Unobtrusive Multimodal Biometrics for Ensuring Privacy and Information Security with Personal Devices BIBAFull-Text 187-201
  Elena Vildjiounaite; Satu-Marja Mäkelä; Mikko Lindholm; Reima Riihimäki; Vesa Kyllönen; Jani Mäntyjärvi; Heikki Ailisto
The need for authenticating users of ubiquitous mobile devices is becoming ever more critical with the increasing value of information stored in the devices and of services accessed via them. Passwords and conventional biometrics such as fingerprint recognition offer fairly reliable solutions to this problem, but these methods require explicit user authentication and are used mainly when a mobile device is being switched on. Furthermore, conventional biometrics are sometimes perceived as privacy threats. This paper presents an unobtrusive method of user authentication for mobile devices in the form of recognition of the walking style (gait) and voice of the user while carrying and using the device. While speaker recognition in noisy conditions performs poorly, combined speaker and accelerometer-based gait recognition performs significantly better. In tentative tests with 31 users the Equal Error Rate varied between 2% and 12% depending on noise conditions, typically less than half of the Equal Error Rates of individual modalities.
LoKey: Leveraging the SMS Network in Decentralized, End-to-End Trust Establishment BIBAFull-Text 202-219
  Anthony J. Nicholson; Ian E. Smith; Jeff Hughes; Brian D. Noble
People increasingly depend on the digital world to communicate with one another, but such communication is rarely secure. Users typically have no common administrative control to provide mutual authentication, and sales of certified public keys to individuals have made few inroads. The only remaining mechanism is key exchange. Because they are not authenticated, users must verify the exchanged keys through some out-of-band mechanism. Unfortunately, users appear willing to accept any key at face value, leaving communication vulnerable. This paper describes LoKey, a system that leverages the Short Message Service (SMS) to verify keys on users' behalf. SMS messages are small, expensive, and slow, but they utilize a closed network, between devices -- phones -- that are nearly ubiquitous and authenticate with the network operator. Our evaluation shows LoKey can establish and verify a shared key in approximately 30 seconds, provided only that one correspondent knows the other's phone number. By verifying keys asynchronously, two example applications -- an instant messaging client and a secure email service -- can provide assurances of message privacy, integrity, and source authentication while requiring only that users know the phone number of their correspondent.
Scalability in a Secure Distributed Proof System BIBAFull-Text 220-237
  Kazuhiro Minami; David Kotz
A logic-based language is often adopted in systems for pervasive computing, because it provides a convenient way to define rules that change the behavior of the systems dynamically. Those systems might define rules that refer to the users' context information to provide context-aware services. For example, a smart-home application could define rules referring to the location of a user to control the light of a house automatically. In general, the context information is maintained in different administrative domains, and it is, therefore, desirable to construct a proof in a distributed way while preserving each domain's confidentiality policies. In this paper, we introduce such a system, a secure distributed proof system for context-sensitive authorization and show that our novel caching and revocation mechanism improves the performance of the system, which depends on public key cryptographic operations to protect confidential information in rules and facts. Our revocation mechanism maintains dependencies among facts and recursively revokes across multiple hosts all the cached facts that depend on a fact that has become invalid. Our initial experimental results show that our caching mechanism, which maintains both positive and negative facts, significantly reduces the latency for handling a logical query.
Secure Mobile Computing Via Public Terminals BIBAFull-Text 238-253
  Richard Sharp; James Scott; Alastair R. Beresford
The rich interaction capabilities of public terminals can make them more convenient to use than small personal devices, such as smart phones. However, the use of public terminals to handle personal data may compromise privacy. We present a system that enables users to access their applications and data securely using a combination of public terminals and a more trusted, personal device. Our system (i) provides users with capabilities to censor the public terminal display, so that it does not show private data; (ii) filters input events coming from the public terminal, so that maliciously injected keyboard/pointer events do not compromise privacy; and (iii) enables users to view personal information and perform data-entry via their personal device. A key feature of our system is that it works with unmodified applications. A prototype implementation of the system has been publicly released for Linux and Windows. The results arising from a pilot usability study based on this implementation are presented.
iCAP: Interactive Prototyping of Context-Aware Applications BIBAFull-Text 254-271
  Anind K. Dey; Timothy Sohn; Sara Streng; Justin Kodama
Although numerous context-aware applications have been developed and there have been technological advances for acquiring contextual information, it is still difficult to develop and prototype interesting context-aware applications. This is largely due to the lack of programming support available to both programmers and end-users. This lack of support closes off the context-aware application design space to a larger group of users. We present iCAP, a system that allows end-users to visually design a wide variety of context-aware applications, including those based on if-then rules, temporal and spatial relationships and environment personalization. iCAP allows users to quickly prototype and test their applications without writing any code. We describe the study we conducted to understand end-users' mental models of context-aware applications, how this impacted the design of our system and several applications that demonstrate iCAP's richness and ease of use. We also describe a user study performed with 20 end-users, who were able to use iCAP to specify every application that they envisioned, illustrating iCAP's expressiveness and usability.
iCam: Precise at-a-Distance Interaction in the Physical Environment BIBAFull-Text 272-287
  Shwetak N. Patel; Jun Rekimoto; Gregory D. Abowd
Precise indoor localization is quickly becoming a reality, but application demonstrations to date have been limited to use of only a single piece of location information attached to an individual sensing device. The localized device is often held by an individual, allowing applications, often unreliably, to make high-level predictions of user intent based solely on that single piece of location information. In this paper, we demonstrate how effective integration of sensing and laser-assisted interaction results in a handheld device, the iCam, which simultaneously calculates its own location as well as the location of another object in the environment. We describe how iCam is built and demonstrate how location-aware at-a-distance interaction simplifies certain location-aware activities.
Gesture Signature for Ambient Intelligence Applications: A Feasibility Study BIBAFull-Text 288-304
  Elisabetta Farella; M. Sile O'Modhrain; Luca Benini; Bruno Riccò
This work investigates the feasibility of a personal verification system using gestures as biometric signatures. Gestures are captured by low-power, low-cost tri-axial accelerometers integrated into an expansion pack for palmtop computers. The objective of our study is to understand whether the mobile system can recognize its owner by how she/he performs a particular gesture, acting as a gesture signature. The signature can be used for obtaining access to the mobile device, but the handheld device can also act as an intelligent key to provide access to services in an ambient intelligence scenario. Sample gestures are analyzed and classified using supervised and unsupervised dimensionality reduction techniques. Results on a set of benchmark gestures performed by several individuals are encouraging.
Exploring the Effects of Target Location Size and Position System Accuracy on Location Based Applications BIBAFull-Text 305-320
  Cliff Randell; Erik Geelhoed; Alan J. Dix; Henk L. Muller
We describe an examination of various physical and human factors which influence the effectiveness of location-based applications. By varying both the target location size and position system accuracy, and hence the ease of use of an application, we are able to identify physical constraints which apply as well as quantifying performance and evaluating human factors. A movement analysis is proposed which allows us to formulate a set of equations that relate the time to find the target to the target location size, distance and positioning system accuracy. We validate our work using a game based application, digital hopscotch, in which the location size and the accuracy of the positioning system are varied. A further set of tests is performed outdoors using a GPS-based application. We show that the results from these experiments concur with the results from our equations. This work may be usefully embedded in software packages that allow designers to build location-based applications.
Displays in the Wild: Understanding the Dynamics and Evolution of a Display Ecology BIBAFull-Text 321-336
  Elaine M. Huang; Elizabeth D. Mynatt; Jay P. Trimble
Large interactive display systems are becoming increasingly pervasive, but most have been studied in isolation, rather than in the context of other technologies in the environment. We present an in-depth field evaluation of large interactive displays within a multi-display work environment used in the NASA Mars Exploration Rover (MER) missions, a complex and authentic use setting. We uncover how the role of such displays evolves in the context of other displays as tasks and collaboration practices change, as well as how tasks migrate among different displays over time. Finally, we present suggestions for how to evaluate the success of large interactive displays and multi-display environments in collaborative work environments based on our findings.
Modeling Human Behavior from Simple Sensors in the Home BIBAFull-Text 337-348
  Ryan Aipperspach; Elliot Cohen; John F. Canny
Pervasive sensors in the home have a variety of applications including energy minimization, activity monitoring for elders, and tutors for household tasks such as cooking. Many of the common sensors today are binary, e.g. IR motion sensors, door close sensors, and floor pressure pads. Predicting user behavior is one of the key enablers for applications. While we consider smart home data here, the general problem is one of predicting discrete human actions. Drawing on Activity Theory, the language as action principle, and speech understanding research, we argue that smoothed n-grams are very appropriate for this task. We built such a model and applied it to data gathered from 3 smart home installations. The data showed a classic Zipf or power-law distribution, similar to speech and language. We found that the predictive accuracy of the n-gram model ranges from 51% to 39%, which is significantly above the baseline for the deployments of 16, 76 and 70 sensors. While we cannot directly compare this result with other work (lack of shared data), by examination of high entropy zones in the datasets (e.g. the kitchen triangle) we argue that accuracies around 50% are best possible for this task.
Using a Live-In Laboratory for Ubiquitous Computing Research BIBAFull-Text 349-365
  Stephen S. Intille; Kent Larson; Emmanuel Munguia Tapia; Jennifer Beaudin; Pallavi Kaushik; Jason Nawyn; Randy Rockinson
Ubiquitous computing researchers are increasingly turning to sensor-enabled "living laboratories" for the study of people and technologies in settings more natural than a typical laboratory. We describe the design and operation of the PlaceLab, a new live-in laboratory for the study of ubiquitous technologies in home settings. Volunteer research participants individually live in the PlaceLab for days or weeks at a time, treating it as a temporary home. Meanwhile, sensing devices integrated into the fabric of the architecture record a detailed description of their activities. The facility generates sensor and observational datasets that can be used for research in ubiquitous computing and other fields where domestic contexts impact behavior. We describe some of our experiences constructing and operating the living laboratory, and we detail a recently generated sample dataset, available online to researchers.
The Diet-Aware Dining Table: Observing Dietary Behaviors over a Tabletop Surface BIBAFull-Text 366-382
  Keng-hao Chang; Shih-yen Liu; Hao-Hua Chu; Jane Yung-jen Hsu; Cheryl Chia-Hui Chen; Tung-yun Lin; Chieh-Yu Chen; Polly Huang
We are what we eat. Our everyday food choices affect our long-term and short-term health. In the traditional health care, professionals assess and weigh each individual's dietary intake using intensive labor at high cost. In this paper, we design and implement a diet-aware dining table that can track what and how much we eat. To enable automated food tracking, the dining table is augmented with two layers of weighing and RFID sensor surfaces. We devise a weight-RFID matching algorithm to detect and distinguish how people eat. To validate our diet-aware dining table, we have performed experiments, including live dining scenarios (afternoon tea and Chinese-style dinner), multiple dining participants, and concurrent activities chosen randomly. Our experimental results have shown encouraging recognition accuracy, around 80%. We believe monitoring the dietary behaviors of individuals potentially contribute to diet-aware healthcare.
Lessons for the Future: Experiences with the Installation and Use of Today's Domestic Sensors and Technologies BIBAFull-Text 383-399
  Mark Stringer; Geraldine Fitzpatrick; Eric Harris
Domestic environments are receiving increasing attention as sites of deployment for pervasive technologies, as evidenced by the growing number of studies of homes and maturing technologies in prototype aware/smart homes. The challenge now is to move technologies out of purpose built homes into everyday environments in ways that will fit with existing buildings and the people who live in them. However, there are many aspects of this future vision that people live with right now in the form of sensors and technologies already in the home. We describe findings from three studies -- in-home interviews, a questionnaire about home sensors, and interviews with commercial smart home installers -- that explore current experiences with sensors and technologies in the home. These lead us to reflect on the implicit assumptions in, and future design directions for, pervasive research for the home.