RFID Tags Help Robots Make Sense of the World

July 17, 2015 | 00:26
RFID Tags Help Robots Make Sense of the World
RFID Tags Help Robots Make Sense of the World
Researchers want to connect the outdoors to the Internet of Things by slapping RFID sensor tags on bridges, buildings and farmland. Rather than hooking up the entire earth to WiFi, mobile robots visit the tags on a regular basis to collect the data.

The rapid price drop of Radio Frequency Identification tags brings massive distribution within reach. RFID tags, currently mostly used to keep track of goods in transit, can, when outfitted with sensing capabilities be utilized to monitor infrastructure or crops.

Tags can also help robots navigate the world. Instead of robots having to figure out everything by themselves using their own sensing capabilities (camera's, lasers, ultrasound), RFID tagged objects can just tell the robot what they are, where they are and what it should do with them.

Four academic researchers, Jennifer Wang (MIT), Erik Schluntz (Harvard University), Brian Otis (University of Washington) and Travis Deyle (Duke University), wrote a paper on how they used sensorized RFID tags to set up an experimental 'smart field': IT-enhanced farmland that collects and communicates data about water levels, plant health, solar radiation and so on.

Smart fields aren't new, systems using cameras have already proved useful to get better informational awareness about the state of the crop. Even sensor networks which wirelessly transmit data to a base station have been used to this end. However, to actively transmit - over Bluetooth Low Energy (BLE) for instance - each sensor needs its own power source. The novel approach of Wang and colleagues is they use battery-free RFID tags.

Rather than relying on a battery the energy needs of the RFID tags are provided by the RFID reader, each time the reader swings by to collect data, the tags harvest the RF power it broadcasts. Wang & co worked with ultra-high frequency RFIDs because they can be read from several meters away. Low-frequency and high-frequency RFIDs have a range of only 5 to 10 centimeters.

Battery-free UHF RFID tags have several advantages over BLE sensors. At less than $0.10, they are much cheaper than BLE technology which costs around $3, according to the researchers. They're smaller, the size of a grain of sand whereas the BLEs are postage stamp sized. Perhaps most importantly, their lifetime spans decades rather than months or years because they don't run out of batteries. These qualities make the battery-free UHF tags good candidates for ubiquitous sensor deployment.

In their smart field experiment the researchers placed several Farsens Hydro Tags - commercially available UHF RFID tags that measure soil moisture – in a field. They mounted UHF RFID readers on two robots and programmed them to autonomously collect the data. The first robot was an unmanned aerial vehicle, the second an unmanned ground vehicle. The robots were given the GPS coordinates of the tags and instructions to establish communication.

The robots checked the ID against a whitelist before reading out the data. For privacy reasons, the robotic RFID herder only communicates with its own flock.

Not all went well in the experiment. The UAV especially had trouble establishing contact with its tags and managed only to read out a few of them. The UGV did a better job and managed to engage with most of the tags assigned to it.

Wang and colleagues conclude that there are still many challenges to overcome before both the robots and the UHF RFID tags are advanced enough to build ubiquitous remote sensor systems. However, the idea is an inspiring one. Especially when technology develops to the point where robots could not only collect data but act upon the information they receive.

A New Vision for Smart Objects and the Internet of Things: Mobile Robots and Long-Range UHF RFID Sensor Tags

Via: ieee.org

Image: Farmland, Muttons Lane by Adrian Cable. CC-SA license.
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