Coordinated Static and Mobile Sensing for Environmental Monitoring

Distributed embedded sensor networks are now being successfully deployed in environmental monitoring of natural phenomena as well as for applications in commerce and physical security. While substantial progress in sensor network performance has appeared, new challenges have also emerged as these systems have been deployed in the natural environment. First, in order to achieve minimum sensing fidelity performance, the rapid spatiotemporal variation of environmental phenomena requires impractical deployment densities. The presence of obstacles in the environment introduces sensing uncertainty and degrades the performance of sensor fusion systems in particular for the many new applications of image sensing. The physical obstacles encountered by sensing may be circumvented by a new mobile sensing method or Networked Infomechanical Systems (NIMS). NIMS integrates distributed, embedded sensing and computing systems with infrastructure-supported mobility. NIMS now includes coordinated mobility methods that exploits adaptive articulation of sensor perspective and location as well as management of sensor population to provide the greatest certainty in sensor fusion results. The architecture, applications, and implementation of NIMS will be discussed here. In addition, results of environmentally-adaptive sampling, and direct measurement of sensing uncertainty will be described

A hybrid sensor network for watershed monitoring

This thesis discusses the Hydrological Hybrid Communication Sensor Network (HHCSN), which is designed for in situ measurement of various hydrological properties of a watershed. HHCSN is comprised of a network of sensor strings, each of which connects up to 100 sensing nodes on a communication line as long as 100 m. Each node includes sensors that measure soil attributes of interest, as well as a microcontroller with basic communication and processing capabilities. A relay point at the surface compresses data from the nodes and wirelessly transmits it to a base station that serves as a gateway to the outside world. The base station compresses data from multiple strings and utilizes the GSM cellular infrastructure to communicate the data to a remote server and to receive software updates to be disseminated to the sensor strings. Ultra-low power design and remote maintenance result in an unattended eld life of over ve years. The system is scalable in area and sensor design modality, as covering a larger area would only entail the addition of sensor strings, and the nodes are designed to facilitate the interfacing of additional sensors. The system is robust, as the only exposed portion is the relay point. Data collection and transmission can be event-driven or time-driven. Battery power, which is supplemented by solar harvesting, and wireless short- and long-range communication, eliminate the need for surface wiring, signicantly reducing the cost of system deployment. Currently, the estimate is a cost of less than $40 for each sensor string, which compares very favorably to the price of existing systems, most of which oer very limited in situ measurement capabilities, yet cost tens of thousands of dollars --Abstract, page iii