Early warmups in March or April can feel good to most people, but it can also cause major problems in orchards, especially if temperatures suddenly tumble below freezing.

Now, Penn State researchers are working on giving growers a leg up on Mother Nature with the use of drones and robots. The university has gotten $843,000 from the National Science Foundation for the three-year project that is looking at monitoring temperatures using drones and robots with the goal of creating an autonomous system to heat up trees when needed.

Growers try to prevent frost damage in their orchards by using sprinklers to form ice on branches to trap the plants’ heat. They also use portable heaters and fans to mix colder air at ground level during a temperature inversion with warmer air that is higher in the atmosphere. But Dana Choi, assistant professor of agricultural and biological engineering, says these methods are resource intensive and inefficient.

Drones will be used to monitor temperatures when frost is expected. The idea is for the drones to send commands to ground-based robots with heaters mounted on them to better target places where frost damage is likely.

"The project will integrate autonomous vehicles, real-time data analytics, decision making and internet of things (IoT) communications to significantly reduce the cost and increase the precision of frost protection of fruit trees," Choi said in a press release.

The project, which will officially begin in June, will include two drones, one of which will be equipped with a high-definition thermal camera. She says the drones and robots will be equipped with sensors and cameras to track not only temperature, but also the state of the plants and whether they are flowering or not.

“The ultimate goal is to avoid any sort of damage from the cold nights,” she says, adding that the goal is to eventually provide a 100% autonomous system for growers to use. The research will take place at the university’s 2.5-acre research farm at Rock Springs, but the plan is to eventually expand it to a commercial orchard in Adams County.

The robots will be equipped with gas-powered heathers, but researchers are also experimenting with a microwave heating system that was originally developed for use in the military.

Developing drone knowledge

A separate project led by Joe Sommer, professor of mechanical engineering, is looking at helping growers fly small drones, get images of their orchard and then use that information to make decisions in the field.

Sommer says drones are already widely used in row crops in the Midwest, so he’s trying to find the value of using them in orchards.

“It's really proven its value out there, but it really hasn’t been used a lot out here,” he says.

Last summer, researchers did low-level flights in the spring to count the number of blossoms per tree, correlating that to manual hand counts of blossoms.

“We got really good correlations between the unmanned aircraft and the manual counts,” he says.

Then, in the fall, they counted apples before harvest and their condition based on their color. He says they saw good correlation between the drones and manual counts of apples on the trees.

The value in the research, he says, is to give growers the option to monitor their trees without having to go into the orchards and do hand-counts.

He says drones are much easier to operate now. He recommends flying over orchards at 200 feet with the camera straight down. Images can then be glued together to create mosaic images of the orchard.

He says high-density plantings are easier to do this work in because you can do more rows at a time.

He recommends doing 50 acres at a time, about a 20-minute flight, where a drone can take up to 400 pictures.

He says they are developing computer programs to track blossom and fruit counts as well as databases that can hold this information.

Most of these small drones can cost between $1,000 and $2,000, though some larger drones can cost up to $8,000, he says.