Without knowing what they’re called, it’s still very likely you’re familiar with radio-frequency identification (RFID) tags. They use electromagnetic fields to automatically identify and track tags attached to objects. In the livestock industry, they’re often found in the ear tags of cows. They’re often used to keep track of inventory in horticultural operations as well, but scanning hundreds or even thousands of individual tags can be a daunting task.
Thankfully, technology is coming to the rescue. Matt Chappell, Ph.D., of Virginia Tech presented “RFID and Beyond: Using RFID, Drones and BLE to Improve Crop Inventory Management” at this year’s Cultivate’21, discussing a potential method to improve inventory data accuracy, quality control, irrigation management and pesticide application.
Professor and director of Virginia Tech’s Tidewater Agricultural Research and Extension Center, Chappell said this project began a decade ago with the goal of getting inventory on the ground (the count, grade, yield and plant size) with aerial imagery. As technology has grown better, data gatherers can see bigger pictures with better detail.
“The objective is to develop and promote sustainable strategies that improve the profitability of the nursery industry,” Chappell said. That means using unmanned aerials systems (UAS, or drones), RFID and Bluetooth Low Energy (BLE). RFID tags are passive and have no energy source, so a reader has to scan them. BLE can emit data, but since it’s newer tech, it’s still very expensive.
To try to solve the issue, Chappell showed off an RFID module that costs about $500 to assemble, weighs 24 pounds and can attach to a drone. (Depending on what you buy, RFID tags cost about a half-cent to eight cents each.) The module stores scanned data on an SD card, and it downloads the information to a base station. Since it’s constantly transmitting data, it does take up a lot of energy.
Chappell and his team tested 12 different RFID tag options to discover which would work best with their airborne module. They performed indoor tests first before heading out into the field to try reading tags from farther distances. They found that horizontal orientation resulted in the highest number of tags scanned, and more were scanned at a slightly higher elevation (25 feet vs. anything height below that). They also found that humidity can affect the effectiveness of reading. The team ultimately narrowed down the field to four tags with the best readability. The scan rate also increases when the drone is in motion (at 6 mph) as compared to when it’s in one place.
“The goal is to get all the data it needs in one pass,” Chappell said. The module information is part of open source technology through Clemson University, so other research teams can include their input.
Once they have the best reader/tag combination available, the next step is creating an RFID sticker tag that will remain durable outside for up to 24 months.