Kristof Van Laerhoven

Advanced Interaction in Context

Mobile information appliances are increasingly used in numerous different situations and locations, setting new requirements to their interaction methods. When the users situation, place or activity changes, the functionality of the device should adapt to these changes. In this work we propose a layered real-time architecture for this kind of context-aware adaptation based on redundant collections of low-level sensors. Two kinds of sensors are distinguished: physical and logical sensors, which give cues from environment parameters and host information. A prototype board that consists of eight sensors was built for experimentation. The contexts are derived from cues using real-time recognition software, which was constructed after experiments with Kohonens Self-Organizing Maps and its variants. A personal digital assistant (PDA) and a mobile phone were used with the prototype to demonstrate situational awareness. On the PDA font size and backlight were changed depending on the demonstrated contexts while in mobile phone the active user profile was changed. The experiments have shown that it is feasible to recognize contexts using sensors and that context information can be used to create new interaction metaphors.

Context Acquisition Based on Load Sensing

Load sensing is a mature and robust technology widely applied in process control. In this paper we consider the use of load sensing in everyday environments as an approach to acquisition of contextual information in ubiquitous computing applications. Since weight is an intrinsic property of all physical objects, load sensing is an intriguing concept on the physical-virtual boundary, enabling the inclusive use of arbitrary objects in ubiquitous applications. In this paper we aim to demonstrate that load sensing is a versatile source of contextual information. Using a series of illustrative experiments we show that using load sensing techniques we can obtain not just weight information, but object position and interaction events on a given surface. We describe the incorporation of load-sensing in the furniture and the floor of a living laboratory environment, and report on a number of applications that use context information derived from load sensing.

Using an autonomous cube for basic navigation and input

This paper presents a low-cost and practical approach to achieve basic input using a tactile cube-shaped object, augmented with a set of sensors, processor, batteries and wireless communication. The algorithm we propose combines a finite state machine model incorporating prior knowledge about the symmetrical structure of the cube, with maximum likelihood estimation using multivariate Gaussians. The claim that the presented solution is cheap, fast and requires few resources, is demonstrated by implementation in a small-sized, microcontroller-driven hardware configuration with inexpensive sensors. We conclude with a few prototyped applications that aim at characterizing how the familiar and elementary shape of the cube allows it to be used as an interaction device.

Long term activity monitoring with a wearable sensor node

This paper introduces an encapsulated sensor node that is devised to monitor and record motion patterns over long, quotidian periods of time with potential application in psychological studies. Its design fuses different sensing modalities to allow efficient capturing of tilt and acceleration stimuli, as well as embedded algorithms that abstract from the raw sensory data to indicative features. By combining tilt switches and accelerometers with customized processing techniques, it is argued that a power-efficient yet information-rich approach is reached for the observation and logging of human motion-based activity

Pin&Play: Networking Objects through Pins

We introduce a new concept of networking objects in everyday environments. The basic idea is to build on the familiar use of surfaces such as walls and boards for attachment of mundane objects such as light controls, pictures, and notes. Hence our networking concept entails augmentation of such surfaces with conductive material to enable them as communication medium. It further incorporates the use of simple pushpin-connectors through which objects can be attached to network-enabled surfaces. Thereby users are provided with a highly familiar mechanism for adding objects ad hoc to the bus network, hence its name Pin&Play. This paper describes the architecture and principles of Pin&Play, as well as the design and implementation of a smart notice-board as proof of concept.

Combining wearable and environmental sensing into an unobtrusive tool for long-term sleep studies

Long-term sleep monitoring of patients has been identified as a useful tool to observe sleep trends manifest themselves over weeks or months for use in behavioral studies. In practice, this has been limited to coarse-grained methods such as actigraphy, for which the levels of activity are logged, and which provide some insight but have simultaneously been found to lack accuracy to be used for studying sleeping disorders. This paper presents a method to automatically detect the users sleep at home on a long-term basis. Inertial, ambient light, and time data tracked from a wrist-worn sensor, and additional night vision footage is used for later expert inspection. An evaluation on over 4400 hours of data from a focus group of test subjects demonstrates a high re-call night segment detection, obtaining an average of 94%. Further, a clustering to visualize reoccurring sleep patterns is presented, and a myoclonic twitch detection is introduced, which exhibits a precision of 74%. The results indicate that long-term sleep pattern detections are feasible.

Detecting leisure activities with dense motif discovery

This paper proposes an activity inference system that has been designed for deployment in mood disorder research, which aims at accurately and efficiently recognizing selected leisure activities in week-long continuous data. The approach to achieve this relies on an unobtrusive and wrist-worn data logger, in combination with a custom data mining tool that performs early data abstraction and dense motif discovery to collect evidence for activities. After presenting the system design, a feasibility study on weeks of continuous inertial data from 6 participants investigates both accuracy and execution speed of each of the abstraction and detection steps. Results show that our method is able to detect target activities in a large data set with a comparable precision and recall to more conventional approaches, in approximately the time it takes to download and visualize the logs from the sensor.

Ubiquitous interaction - using surfaces in everyday environments as pointing devices

To augment everyday environments as interface to computing may lead to more accessible and inclusive user interfaces, exploiting affordances existing in the physical world for interaction with digital functionality. A major challenge for such interfaces is to preserve accustomed uses while providing unobtrusive access to new services. In this paper we discuss augmentation of common surfaces such as tables as generic pointing device. The basic concept is to sense the load, the load changes and the patterns of change observed on a surface using embedded load sensors. We describe the interaction model used to derive pointing actions from basic sensor observations, and detail the technical augmentation of two ordinary tables that we used for our experiments. The technology effectively emulates a serial mouse, and our implementation and use experience prove that it is unobtrusive, robust, and both intuitively and reliably usable.

Already up? using mobile phones to track & share sleep behavior

Users share a lot of personal information with friends, family members, and colleagues via social networks. Surprisingly, some users choose to share their sleeping patterns, perhaps both for awareness as well as a sense of connection to others. Indeed, sharing basic sleep data, whether a person has gone to bed or waking up, informs others about not just ones sleeping routines but also indicates physical state, and reflects a sense of wellness. We present Somnometer, a social alarm clock for mobile phones that helps users to capture and share their sleep patterns. While the sleep rating is obtained from explicit user input, the sleep duration is estimated based on monitoring a users interactions with the app. Observing that many individuals currently utilize their mobile phone as an alarm clock revealed behavioral patterns that we were able to leverage when designing the app. We assess whether it is possible to reliably monitor ones sleep duration using such apps. We further investigate whether providing users with the ability to track their sleep behavior over a long time period can empower them to engage in healthier sleep habits. We hypothesize that sharing sleep information with social networks impacts awareness and connectedness among friends. The result from a controlled study reveals that it is feasible to monitor a users sleep duration based just on her interactions with an alarm clock app on the mobile phone. The results from both an in-the-wild study and a controlled experiment suggest that providing a way for users to track their sleep behaviors increased user awareness of sleep patterns and induced healthier habits. However, we also found that, given the current broadcast nature of existing social networks, users were concerned with sharing their sleep patterns indiscriminately.

Teaching Context to Applications

Abstract: Although mobile devices keep getting smaller and more powerful, their interface with the user is still based on that of the regular desktop computer. This implies that interaction is usually tedious, while interrupting the user is not really desired in ubiquitous computing. We propose adding an array of hardware sensors to the system that, together with machine learning techniques, make the device aware of its context while it is being used. The goal is to make it learn the context-descriptions from its user on the spot, while minimising user-interaction and maximising reliability.