The device engineered by a team of UW-Madison researchers uses microwave imaging to collect data on cranberries.

As a University of Wisconsin-Madison computer and electrical engineering professor, Susan Hagness doesn’t typically field emails about cranberry farming. Her background is in cancer detection, not agriculture.

But when she saw a message from a cranberry researcher asking for help in her inbox last year, she knew it was a problem her team could solve.

“We felt we had the perfect expertise to tackle this,” she said. “We felt it was a natural win-win situation.”

The cranberry researcher was an employee with the multinational food brand Ocean Spray, asking for insight on cranberry counting. To estimate the size of a crop, modern growers currently use old-fashioned methodology: They pick all the berries in a square-foot patch of bushes, and then do a hand-count. 

Hagness, UW-Madison engineering professor John Booske and graduate student researcher Alex Haufler have now come up with a prototype for a better way: a boxy scanning device that looks like a computer case mounted on PVC pipes.

The array can be mounted directly above a cranberry bed, and through using electromagnetic pulses, “read” the bramble. From those readings, a count can be generated.

It’s a piece of technology that Hagness said could improve the efficiency and accuracy of cranberry counts in the state.

“This is a great example of a relationship between a really important state industry and our university,” she said.

The cranberry industry in Wisconsin is indeed a huge agricultural sub-sector. According to the Wisconsin State Cranberry Growers Association, about 60 percent of the nation’s cranberry yield comes from Wisconsin.

For those in the industry, berry counts are vital. For growers, yield estimates can help them take stock of harvests, and see how adjustments they make in their farming techniques affect out put.

“If they can correlate farming practices with yield improvements, they can fully adopt these new practices,” noted Hagness.

Others benefit too: Handlers further down the supply chain need to estimate how much storage they’ll need for berries, while scientists who genetically engineer cranberries rely on the data for their research.

With their backgrounds in applied electromagnetics, Hagness and company were well-suited to come up with a solution to cranberry counting. Microwaves have long been used in applications in things like medical imaging and for assessing the integrity of bridges. Much like radar is used to detect moisture in clouds in meteorology, it stood to reason that using microwave pulses on a cranberry bed could be used to read moisture and come up with a berry count.

The first stage of developing the technology involved “measuring” the different components of a cranberry bush from an electromagnetic perspective.

“We wanted to come up with the properties of all parts of the canopy,” Haufler explained.

The researchers found that berries had traits that drastically contrasted those of the stems and leaves — in other words, berries would easily stand out in scans. From there, it was a question of running test scans in computer generated models of cranberry crops, before building a prototype and taking it out to Wisconsin cranberry fields in Junction City and Neenah for testing.

With the data they collected, it’s now a question of finessing computer algorithms to generate the actual count. The team will then check the accuracy of their tally with the hand-count of the producers.

Ocean Spray and the state growers association funded the project. Ocean Spray, a large cooperative of cranberry farmers, also provided two of its members’ fields for testing. Hagness said it’s typical for her department to field such engineering projects from the private sector.

“We have tremendous interactions with industrial partners from across the board,” she said.

Hagness said that the plan is to conduct more tests in the coming year, this time with the device mounted on a boom attached to a truck to collect even more data for the research project. From there, said Hagness, she’d like to help disseminate the technology to Wisconsin producers.

“It is not our intention to patent this technology,” she said. “I would envision working with the farmers in the state to provide them with a system where anyone who wants one can get one.”

Erik Lorenzsonn is the Capital Times' tech and culture reporter. He joined the team in 2016, after having served as an online editor for Wisconsin Public Radio and having written for publications like The Progressive Magazine and The Poughkeepsie Journal.

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