Implementing assisted navigation in hybrid sensor networks

In hybrid sensor networks (HSNs) one or more mobile sensor nodes can interact with other mobile sensor nodes or static ones in order to collaboratively perform specific tasks. Such networks can support applications in which assisted navigation is implemented for mobile sensor nodes that carry out requested operations through a monitored environment. To this end, several assisted navigation algorithms have been proposed within the HSNs scope with the goal of overcoming the typical problems of classic sensor networks (SNs), such as limited transmission power and lean autonomy in terms of computing and memory capacity. Nevertheless, the distributed and highly dynamic nature of such algorithms still makes their implementation in a real scenario a difficult task. In this paper we present an improved version of the assisted navigation algorithm based on the "credit field" concept. The algorithm has been designed for HSNs and implemented in Agilla, a middleware running on top of TinyOS and supporting a programming paradigm based on mobile agents. The implementation has been tested on a HSN that employs Mica2 Motes as static sensor nodes and the Lego Mindstorms robot integrated with a Stargate node developed by Crossbow as a mobile sensor node.