Showing papers on "Sensor hub published in 2009"

Sensor Networks in the Real World

Abstract: The system we propose, AdapSys, is based on a fundamental unit that can perform at a very high level of abstraction - a multi-level controller and sensor hub that is completely software reconfigurable, including basic and ancillary functionality. In this scheme, each unit can act as a single complex controller as part of a locally controlled mesh, which in turn can be part of a wider distributed or hierarchical control network. All elements of this system consist of the same hardware, but have fundamentally fluid behaviors based on software adaptivity and reconfigurability. We want to know what our structures are doing: structures in the big sense, from our bodies up to large industrial processes, airframes and buildings. This has traditionally been a troublesome and expensive problem. Recent improvements in sensors based on Micro-Electro-Mechanical Systems (MEMS) and in wireless technology have allowed the proliferation of wireless sensor networks, and these have completely changed what we can measure. Each element of the network is commonly called a 'mote' or smart sensor. Motes are combined into large networks that allow dense and detailed sensing. These networks move beyond the idea of a sensor as a single instrument measuring one thing, to a comprehensive system consisting of many small nodes working cooperatively. Engineering and science, however, remain captive to the traditional hierarchical embedded system. This experience has led us to devise a new monitoring and control appliance, each interacting in an organic network. Here is an example of the current state of practice. During 2006 a mote network was designed, implemented, deployed and tested on the Golden Gate Bridge in San Francisco, in order to monitor its structural condition. Sixtyfour motes were distributed over the main span and southern tower (see Figure 1), comprising the largest wireless vibration sensor network ever installed for structural health monitoring purposes. The spatially dense array resulted in an increase in effective signal-to-noise ratio compared to single, isolated, sensors, and most importantly allowed the higher modes, both vertical and torsional, to be analyzed easily and accurately.