Felix Büsching

The GINSENG system for wireless monitoring and control: Design and deployment experiences

Todays industrial facilities, such as oil refineries, chemical plants, and factories, rely on wired sensor systems to monitor and control the production processes. The deployment and maintenance of such cabled systems is expensive and inflexible. It is, therefore, desirable to replace or augment these systems using wireless technology, which requires us to overcome significant technical challenges. Process automation and control applications are mission-critical and require timely and reliable data delivery, which is difficult to provide in industrial environments with harsh radio environments. In this article, we present the GINSENG system which implements performance control to allow us to use wireless sensor networks for mission-critical applications in industrial environments. GINSENG is a complete system solution that comprises on-node system software, network protocols, and back-end systems with sophisticated data processing capability. GINSENG assumes that a deployment can be carefully planned. A TDMA-based MAC protocol, tailored to the deployment environment, is employed to provide reliable and timely data delivery. Performance debugging components are used to unintrusively monitor the system performance and identify problems as they occur. The article reports on a real-world deployment of GINSENG in an especially challenging environment of an operational oil refinery in Sines, Portugal. We provide experimental results from this deployment and share the experiences gained. These results demonstate the use of GINSENG for sensing and actuation and allow an assessment of its ability to operate within the required performance bounds. We also identify shortcomings that manifested during the evaluation phase, thus giving a useful perspective on the challenges that have to be overcome in these harsh application settings.

DroidCluster: Towards Smartphone Cluster Computing -- The Streets are Paved with Potential Computer Clusters

What is the processing-power of an omnibus? Can a train compute a climate model? Todays smart phones are becoming more and more powerful and have a performance similar to former high-end workstations. This power can also be used in a joint and cooperative way by building local and mobile ad-hoc clusters. In this paper we will show that setting up a smart phone cluster is not only possible, but it is also a reasonable thing to do, considering the sheer amount of mobile devices and the applications that could benefit from it.

Architecture and evaluation of INGA an inexpensive node for general applications

INGA is a cost-efficient and universal wireless sensor node for activity monitoring and for general applications. INGAs architecture bases on an 8-bit Atmel microcontroller and runs Contiki OS and TinyOS “out of the box”. The motivation to develop INGA was driven by the need for a reasonable, cheap and expandable node for several use cases: On the one hand, in a research project, we intend to do a gait analysis of elderly persons with it, on the other hand we want to equip our student WSN lab with new nodes. For the first case none of the existing nodes fulfilled our requirements concerning assembled sensors and functionality. In this paper, we present the motivation and design for “yet another sensor node” furthermore, we present the detailed architecture and its benefits in comparison to other nodes. The first measurement results using INGA show its characteristics and usability. INGA is completely under open-source license and all resources are provided to the community.

The Lower Saxony research network design of environments for ageing: towards interdisciplinary research on information and communication technologies in ageing societies

Worldwide, ageing societies are bringing challenges for independent living and healthcare. Health-enabling technologies for pervasive healthcare and sensor-enhanced health information systems offer new opportunities for care. In order to identify, implement and assess such new information and communication technologies (ICT) the ‘Lower Saxony Research Network Design of Environments for Ageing’ (GAL) has been launched in 2008 as interdisciplinary research project. In this publication, we inform about the goals and structure of GAL, including first outcomes, as well as to discuss the potentials and possible barriers of such highly interdisciplinary research projects in the field of health-enabling technologies for pervasive healthcare. Although GALs high interdisciplinarity at the beginning slowed down the speed of research progress, we can now work on problems, which can hardly be solved by one or few disciplines alone. Interdisciplinary research projects on ICT in ageing societies are needed and recommended.

Monitoring systems for the support of home care.

In this article, the design of a system for the ambient, unobtrusive and automatic monitoring of Activities of Daily Living (ADL) is described. In the context of the growing imbalance between (potentially young) caregivers and (most often older) people receiving care, technical monitoring systems may help to organise care more efficiently and to identify degrading abilities very early to trigger preventive measures. To improve the acceptance of the system described in this article, the selection process of the sensors to be integrated into the flat or to be worn by the older people has been steered by the results of focus group interviews with older people, their relatives and professional caregivers. The interviews revealed that these people would in general accept such systems, but security, mobility and communication aspects have to be clearly and appropriately addressed. In an experimental study the recognition rate of the activity ‘preparation and intake of food or beverages’ has been measured with two age groups (6 subjects, age between 25 and 40/mean 30 years and 5 subjects, age between 72 and 84/mean 75.3 years). The food preparation was detected with a sensitivity of 74.7% and a specificity of 84.2% using a vision sensor.

Information and communication technologies for promoting and sustaining quality of life, health and self-sufficiency in ageing societies – outcomes of the Lower Saxony Research Network Design of Environments for Ageing (GAL)

Many societies across the world are confronted with demographic changes, usually related to increased life expectancy and, often, relatively low birth rates. Information and communication technologies (ICT) may contribute to adequately support senior citizens in aging societies with respect to quality of life and quality and efficiency of health care processes. For investigating and for providing answers on whether new information and communication technologies can contribute to keeping, or even improving quality of life, health and self-sufficiency in ageing societies through new ways of living and new forms of care, the Lower Saxony Research Network Design of Environments for Ageing (GAL) had been established as a five years research project, running from 2008 to 2013. Ambient-assisted living (AAL) technologies in personal and home environments were especially important. In this article we report on the GAL project, and present some of its major outcomes after five years of research. We report on major challenges and lessons learned in running and organizing such a large, inter- and multidisciplinary project and discuss GAL in the context of related research projects. With respect to research outcomes, we have, for example, learned new knowledge about multimodal and speech-based human–machine-interaction mechanisms for persons with functional restrictions, and identified new methods and developed new algorithms for identifying activities of daily life and detecting acute events, particularly falls. A total of 79 apartments of senior citizens had been equipped with specific “GAL technology”, providing new insights into the use of sensor data for smart homes. Major challenges we had to face were to deal constructively with GAL’s highly inter- and multidisciplinary aspects, with respect to research into GAL’s application scenarios, shifting from theory and lab experimentation to field tests, and the complexity of organizing and, in our view, successfully managing such a large project. Overall it can be stated that, from our point of view, the GAL research network has been run successfully and has achieved its major research objectives. Since we now know much more on how and where to use AAL technologies for new environments of living and new forms of care, a future focus for research can now be outlined for systematically planned studies, scientifically exploring the benefits of AAL technologies for senior citizens, in particular with respect to quality of life and the quality and efficiency of health care.

Comparison and validation of capacitive accelerometers for health care applications

Fall detection, gait analysis and context recognition are examples of applications where capacitive accelerometers are widely used in health care. In most of the existing work, algorithms were developed for a specific platform and accelerometers were used without explicitly choosing a specific type. With this work we present an inexpensive and practical test setup for replicable and repeatable testing of accelerometers. In addition we use this setup to evaluate six of the most commonly available accelerometers today and list their outcomes for linearity, power consumption and correlation of the tested sensors. We also attempt to an answer to the question of whether applications and algorithms developed for one platform and one type of accelerometer can be easily transferred to another accelerometer.

Data elevators: Applying the bundle protocol in Delay Tolerant Wireless Sensor Networks

Delay Tolerant Networking (DTN) enables transfer of data where conventional network protocols fail to deliver data because no continuous end-to-end connectivity is available. While the Bundle Protocol (BP) has been established as the standard DTN protocol in many application areas, Wireless Sensor Networks (WSN) often use proprietary protocols with a subset of the BP features. In this paper we use an exemplary application to demonstrate how the BP can be beneficial for many WSN-based projects. We show, how low-power sensor nodes can transport bundles by exploiting existing movement in the environment. More importantly we show, how 8-bit WSN nodes can seamlessly interact with standard BP implementations running on standard PCs. Our application, a sensor that is installed on the roof of a 15-story building, is using an elevator to transport bundles carrying measured values to our lab. We analytically compare the BP to existing protocols for WSNs, evaluate our application scenario and give insight into principal limitations.

The GAL middleware platform for AAL

GAL, the Lower Saxony Research Network Design of Environments for Ageing, investigates how information and communication technology can provide for better environments for ageing. This paper describes a service oriented middleware platform for Ambient Assisted Living and its use in a number of different assistive systems developed in the GAL project: personal activity and household assistant, monitoring of preventive and rehabilitation sports, sensor-based activity determination, and sensor-based fall prevention and recognition. Besides a detailed description of the middleware platform and its elements and interfaces, central infrastructure services and their particularly applications in the different use cases are presented.

A method to align the coordinate system of accelerometers to the axes of a human body: The depitch algorithm

One of the key problems in accelerometry based gait analyses is that it may not be possible to attach an accelerometer to the lower trunk so that its axes are perfectly aligned to the axes of the subject. In this paper we will present an algorithm that was designed to virtually align the axes of the accelerometer to the axes of the subject during walking sections. This algorithm is based on a physically reasonable approach and built for measurements in unsupervised settings, where the test persons are applying the sensors by themselves. For evaluation purposes we conducted a study with 6 healthy subjects and measured their gait with a manually aligned and a skewed accelerometer attached to the subjects lower trunk. After applying the algorithm the intra-axis correlation of both sensors was on average 0.89±0.1 with a mean absolute error of 0.05g. We concluded that the algorithm was able to adjust the skewed sensor node virtually to the coordinate system of the subject.