Learn how researchers have worked out a battery-free sensor solution to work on wide areas outdoors by leveraging RFID equipped mobile robots.

Battery-free RFID sensors are an interesting approach to sensing solutions where a high volume of sensors need to be scattered around. Using battery aided solutions for these is inefficient due to the cost associated to changing batteries to big amounts of devices.

Battery-free sensors, however, have always had a limiting factor: read range. Even if technology moved from HF devices that could be read at just some centimeters to UHF devices that can be read from over 1.5 meters, lots of applications demand longer communication ranges.

RFID reader equipped drones

The dawn of mobile robots may come handy according to latest research. Both Unmanned Aerial Vehicles (UAVs) and Unmanned Ground Vehicles (UGVs) can be equipped with RFID reader modules.

RFID equipped mobile robot reading a battery-free sensor tag

RFID equipped mobile robot reading a battery-free sensor tag

This means that you have an autonomous and mobile reader out there at your service now. Mobile robots can be programmed to perform specific tasks or drive/fly specific routes and retrieve completely passive sensor information on their way.

The mobile robot and RFID tag solution has been employed for a variety of applications. Some examples are shown below:

Note that these previous articles and papers were aimed at reading just IDs (no sensors on the tags) or at recharging batteries for active Wireless Sensor Network (WSN) nodes.

Battery-free sensor tags implemented

However, this paper from MIT, Harvard, University of Washington and Duke University has been employing Farsens’s Hydro soil moisture battery-free tags along with RFID reader equipped mobile robots (A New Vision for Smart Objects and the Internet of Things: Mobile Robots and Long-Range UHF RFID Sensor Tags).

As Jennifer Wang, Erik Schluntz, Brian Otis and Travis Deyle point out, ‘Perpetual concerns like read range, power budgets, and mobile robot control still play a significant role’ but initial prototype applications have already been demonstrated.

Agriculture, construction, environmental… where’s the limit?