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Monday, March 2, 2009

Gateways into sensor networks

Two technologies in particular seem to be moving toward an interesting convergence: mobile robotics and wireless sensor networks. The two main questions here are:

* Can a mobile robot act as a gateway into a wireless sensor network?
* Can sensor networks take advantage of a robot's mobility and intelligence?

One major issue with a mobile robot acting as a gateway is the communication between the robot and the sensor network. Sensor networks typically communicate using 900 MHz radio waves. Mobile robots use laptops that communicate via 802.11, in the 2.4- to 2.483-GHz range. Intel hopes to prove that a sensor net can be equipped with 802.11 capabilities to bridge the gap between robotics and wireless networks.

Intel recently demonstrated how a few motes equipped with 802.11 wireless capabilities can be added to a sensor network to act as wireless hubs. Other motes in the network then use each other as links to reach the 802.11-equipped hubs. The hubs forward the data packets to the main 802.11-capable gateway, which is usually a laptop. Using some motes as hubs cuts down on the number of hops any one data packet has to make to reach the main gateway. It also reduces power consumption across the sensor net.

Intel believes that one of the most interesting technology convergences will be in designing mobile robots that can act as gateways into the wireless sensor networks. For example, Intel recently installed small sensors in a vineyard in Oregon to monitor microclimates. The sensors measured temperature, humidity, and other factors to monitor the growing cycle of the grapes, then transmitted the data from sensor to sensor until the data reached a gateway. There, the data was interpreted and used to help prevent frostbite, mold, and other agricultural problems.

The agricultural example shows just how a sensor network could take advantage of a mobile robot's capabilities. Over time, sensors need to be recalibrated, just like any other measuring equipment. If a robot could act as a gateway to the sensor network, it could automatically perform tasks such as calibration. For example, a robot could periodically collect data along the network, determine which sensors are out of tolerance, move to the appropriate location, and recalibrate each out-of-tolerance device.

To look into using mobile robots as gateways to such wireless sensor networks, Intel is bringing in a Ph.D. candidate from the University of Southern California, under the guidance of professor Gaurav Sukhatme. This person will work with Intel on integrating wireless sensor networks into robotics research for localization techniques. This type of collaboration is just one example of how Intel is promoting the convergence of microelectronics and robotics.

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