An often-quoted Business Week article from 1999 stated that, “In the next century, planet Earth will don an electric skin…” The electric skin refers to is the concept of the sensor web, where networks of sensors monitor and interact to communicate change over time. The sensor web had its start with NASA’s Jet Propulsion Laboratory and has spread broadly to include both sensors and ecosystems of sensors that have come down dramatically in price, with great improvements in performance and capability.
Communication is the key element of the sensor web. Through the wireless connection, the individual sensors can be programmed remotely and communicated with individually or collectively. Sensors continually share readings with each other, and a grouping or web of sensors for one location can receive communication from a web of sensors in another location.
The web of sensors becomes an intelligent and adaptive network as data from individuals and groups become fused on the fly. Readings from individual pods detecting anomalous events can trigger adaptive behavior in nearby individual pods or the entire sensor network. Adding sensors to systems allows for automation, where readings can trigger a series of events that allow the system to adapt to changing conditions.
Realizations in Real Time
Sensor webs add real-time data into decision support systems. The fact that the sensors share and fuse information amongst themselves provides pre-validation for data so that it can be trusted and acted upon immediately.
The adaptive and distributed nature of the sensor network ensures that the network will continue to collect and communicate information about a changing environment, regardless of sensor failures at individual locations.
What Types of Sensors?
There’s a broad range of different sensors that can be deployed in a sensor web for various observations and purposes—from environmental monitoring, to hazard detection, to security observation, and motion and location.
Sensors might include temperature, moisture, wind, noise, video, infrared, radio frequency, seismic activity, air quality, chemical and biological, etc. Individual sensor web pods might have specific sensors or a cluster of sensors that each inform one another.
Sensor pods don’t have a determined size, shape or function. An individual sensor pod can be towered clusters of sensors such as border patrol monitoring, networks of unmanned aerial vehicles, and sensor clusters at uniformly distributed monitoring sites. There’s also the idea of biodegradable nano sensors that can be seeded on the wind and distributed widely.
Tried and Tested Sensor Networks
There are a number of sensor web projects that have been deployed successfully.
NASA’s Jet Propulsion Lab has designed and deployed a Volcano Sensor Web to monitor scientific readings and hazard levels at 50 of the Earth’s most active volcanoes.
SensorWare Systems, a spin-off of the NASA’s sensor web project, has deployed a number of networks in a variety of environments. Projects have included agricultural sensors to test irrigation methods, a network in Antarctica that tested the performance of their system in the ultimate of harsh conditions, and a flood monitoring network in the Tucson desert.
The U.S. Army is also heavily interested in sensor webs for their Future Combat System and Objective Force for the Warrior Program. They’ve tested a network to coordinate ground sensors, robotic vehicles and unmanned aerial vehicles for battlefield operations.
Earth Monitoring Advancements
An area of ongoing interest is Earth observation. There’s a research movement afoot to connect earth observing satellite sensors with ground-based sensors for optimal use of resources. The combination of these sensors with adaptive earth system models should provide considerable added insight into our planet’s complex systems.
Sensor networks will continue to advance to provide a significant increase in our knowledge and understanding of our planet’s systems and those system’s interactions.