Flexible Sensor Network Reprogramming for Logistics

Besides the currently realized applications, Wireless Sensor Networks can be put to use in logistics processes. However, doing so requires a level of flexibility and safety not provided by the current WSN software platforms. This paper discusses a logistics scenario, and presents SensorScheme, a runtime environment used to realize this scenario, based on semantics of the Scheme programming language. SensorScheme is a general purpose WSN platform, providing dynamic reprogramming, memory safety (sandboxing), blocking I/O, marshalled communication, compact code transport. It improves on the state of the art by making better use of the little available memory, thereby providing greater capability in terms of program size and complexity. We illustrate the use of our platform with some application examples, and provide experimental results to show its compactness, speed of operation and energy efficiency

Distributed Service Discovery for Heterogeneous Wireless Sensor Networks

Service discovery in heterogeneous Wireless Sensor Networks is a challenging research objective, due to the inherent limitations of sensor nodes and their extensive and dense deployment. The protocols proposed for ad hoc networks are too heavy for sensor environments. This paper presents a resourceaware solution for the service discovery problem, which exploits the heterogeneous nature of the sensor network and alleviates the high-density problem from the flood-based approaches. The idea is to organize nodes into clusters, based on the available resources and the dynamics of nodes. The clusterhead nodes act as a distributed directory of service registrations. Service discovery messages are exchanged among the nodes in the distributed directory. The simulation results show the performance of the service discovery protocol in heterogeneous dense environments

Demo Abstract: Service Oriented Wireless Sensor Networks - A Cluster-based Approach

In this paper we demonstrate a service-oriented solution for heterogeneous WSNs. The main operations are service discovery and service usage. Our solution is integrated with mobile platforms (smartphones and PDAs), that act as gateways to the GSM network and the Internet

Are users more diverse than designs? Testing and extending a 25 years old claim

Twenty-five years ago, Dennis Egan published a review on the impact of individual differences in human-computer interaction, where he claimed that users are more diverse than designs are [5]. While being cited frequently, this claim has not been tested since then. An efficient research design for separating and comparing variance components is presented, together with a statistical model to test Egan’s claim. The results of a pilot study indicate that Egan’s claim does not universally hold. An extension to the claim is suggested, capturing the trade-offs when prioritizing user tasks. An alternative strategy towards universal design is proposed

Online Movement Correlation of Wireless Sensor Nodes

Sensor nodes can autonomously form ad-hoc groups based on their common context. We propose a solution for grouping sensor nodes attached on the same vehicles on wheels. The nodes periodically receive the movement data from their neighbours and calculate the correlation coefficients over a time history. A high correlation coefficient implies that the nodes are moving together. We demonstrate the algorithm using two types of movement sensors: tilt switches and MEMS accelerometers. We place the nodes on two wirelessly controlled toy cars, and we observe in real-time the group membership via the LED colours of the nodes. In addition, a graphical user interface running on the base station shows the movement signals over a recent time history, the latest sampled data, the correlation between each two nodes and the group membership

Movement-based Group Awareness with Wireless Sensor Networks

We propose a method through which dynamic sensor nodes determine that they move together, by communicating and correlating their movement information. We describe two possible solutions, one using inexpensive tilt switches, and another one using low-cost MEMS accelerometers. We implement a fast, incremental correlation algorithm, with an execution time of 6ms, which can run on resource constrained devices. The tests with the implementation on real sensor nodes show that the method is reliable and distinguishes between joint and separate movements. In addition, we analyze the scalability from four different perspectives: communication, energy, memory and execution speed. The solution using tilt switches proves to be simpler, cheaper and more energy efficient, while the accelerometer-based solution is more reliable, more robust to sensor alignment problems and, potentially, more accurate by using extended features, such as speed and distance

SensorShoe: Mobile Gait Analysis for Parkinson's Disease Patients

We present the design and initial evaluation of a mobile gait analysis system, SensorShoe. The target user group is represented by Parkinson's Disease patients, which need continuous assistance with the physical therapy in their home environment. SensorShoe analyses the gait by using a low-power sensor node equipped with movement sensors. In addition, SensorShoe gives real-time feedback and therapy assistance to the patient, and provides the caregivers an effective remote monitoring and control tool

Lightweight EDF scheduling with deadline inheritance

EDFI is a lightweight real-time scheduling protocol that combines EDF with deadline inheritance over shared resources. We will show that EDFI is flexible during a tasks admission control, efficient with scheduling and dispatching, and straightforward in feasibility analysis. The application programmer only needs to specify a tasks timing constraints (deadline, period, runtime) and resource needs, after which EDFI can execute admission control, scheduling, dispatching and resource synchronisation automatically. EDFI avoids gratuitous task switching and its programming overhead as well as runtime overhead is very low, which makes it ideal for lightweight and featherweight kernels. We will illustrate the elegance of the underlying theory and we will shortly discuss the implementation of EDFI in three different operating systems

Design of a low-power testbed for Wireless Sensor Networks and verification

In this document the design considerations and component choices of a testbed prototype device for wireless sensor networks will be discussed. These devices must be able to monitor their physical environment, process data and assist other nodes in forwarding sensor readings. For these tasks, five basic parts are necessary in a sensor node: sensor interface, computational unit, memory, communication interface and energy source. Hardware choices for these\ud components will be discussed, as well as an additional debugging interface. The design has been verified by implementation of a few example applications. The testbed includes a tiny preemptive real time operating system