Image of the schematic for the cutting device on one of the drone designs

"Take an existing drone and make it capable of not only cutting a branch from a tree with cones on it, but also carrying that branch away to release and drop it. [That's] a real problem—a hard problem."

Rico Picone, Ph.D.
Mechanical engineering

Every year, the Washington State Department of Natural Resources (DNR) identifies areas throughout the state that are in need of reforestation. According to DNR, although the department maintains a collection of conifer seeds—in various combinations of species, seed zones, and elevations—at the state nursery in Tumwater, the department has to replenish its inventory each year, since the seeds are used for reforestation efforts or degrade over time. In order to preserve the department’s vast seed collection, DNR staff surveys the state to sample cones from selected areas to determine seed fitness and ripeness for collection.

Collecting cones can be a tricky proposition. Many conifer species in the state can attain heights of 200 to 250 feet, so DNR uses several different methods to sample cones, including clipping cones with pole saws; using large slingshots with weighted lines to pull branches or cones from trees; and shooting down branches with rifles. According to DNR, as the state’s population has grown, the use of shooting as a sampling method has become limited due to safety concerns.

DNR wanted to develop a cone sampling process that was easier, safer and more efficient. An idea arose from conversations between staff members at DNR: Could drones be used to help harvest cones? The department had had a drone program in place for a few years, but that had been used primarily for natural resource management and mapping. However, it seemed plausible that drones, if outfitted correctly, could collect cone samples.

It was at this point that DNR reached out to Rico Picone, Ph.D., assistant professor of mechanical engineering in the Hal and Inge Marcus School of Engineering, to ask him about the feasibility of using drones for cone collection. As Picone recalls, it was the spring of 2017 when DNR first approached him. “I told them that I thought it could be done,” he said.

Picone and Saint Martin’s submitted a research grant proposal to DNR for the project and DNR provided funding for the project to move forward. Picone, as principal investigator, recruited a number of students to help work on the project: then-undergraduate students Justin Hummel ’18, Alex Libby ’18, Viktor Stantsiyer ’18, Will Von Dolln ’18, current undergraduates Matthew Thomas, Brianna Huhmann and Jacob Eaton and graduate student Ryan Haseman. He presented them with what he called “A real problem—a hard problem.”

Picone summarized the challenge he gave to the students: “Take an existing drone and make it capable of not only cutting a branch from a tree with cones on it, but also carrying that branch away to release and drop it. Maneuverability and controllability while the drone is in the air will be an issue when you suspend something below it. It also has to be reliable.”

That spring, DNR met with the student teams and gave them more information and criteria. Shortly thereafter, Hummel, Libby, Stantsiyer and Von Dolln decided to make the drone feasibility investigation their senior design project, which would commence in fall 2017. Stantsiyer recalled the group’s initial aims. “At first we thought, we’re going to do research, and the first step is to figure out how to cut [the branches], and then the plan was to move on from there.”

Once the team got started on the project, they quickly discovered that the problem was more complex than they expected and that there were a number of limitations on possible designs. Hummel outlined some of the obstacles they faced when they began thinking of designs for the drones. “When you first look at the problem, you think, ‘Just attach a cutting device to the drone and send it up there on its way.’ But weight’s a big factor and so is power—because you need to power the cutting apparatus off the drone’s batteries,” he said. “There were a lot of ideas that got shut down right away once we started doing the math. One idea was to do something that was spring-loaded, but according to the math, that would’ve required something the size of a car spring—not a good option. Another initial idea was using Hilti charges [charges used in tools like nailguns], but the trouble with that is that DNR often collects cones in August, and with the charges there’s a possibility of starting a fire, so that was out too.”

In spring 2018, Picone approached Thomas, Huhmann and Eaton with a few ideas about the drone project that he wanted to explore with their help. “With some of the concepts that I was working on, the other group was already so far down their own path, so I set up another small group of students to trial another design. In the end, there was a little bit of convergence, because both design ideas ended up working.”

As Thomas said, “We all realized that there’s significance in having two very different designs to play off each other.”

Students from both teams mentioned that one of the aspects they found both challenging and rewarding about the project was how much adaptability it demanded from them. “It’s often better to do calculations first, but in this case there were a lot of dynamic variables, and we could have done calculations for months and not gotten close,” Thomas said. “I think it’s really important, for anyone who does a project like this, to be able to switch in your mind and readjust what you want to do in a second.”

Hummel echoed Thomas’s thoughts. “Before this project, I was all about doing the math first and making sure everything worked. But this project’s taught me that sometimes you can’t do the math. There are some things you have to assume that you’ll work out over time.”

In summer 2018, Hummel, Libby, Stantsiyer and Von Dolln formed a company, Evergreen Drone Applications, LLC, for the successful drone prototype that they’d developed. Stantsiyer explained that the group hopes to continue working with DNR to optimize the prototype and they would like to use their knowledge to create drone modifications for other uses as well. 

Evergreen Drone Applications, LLC, will be one of the first tenants of the Lacey MakerSpace, which is a partnership between the University, the City of Lacey and the Thurston Economic Development Council. The Lacey MakerSpace, located on the Saint Martin's University campus, is a hub for innovation and entrepreneurship that provides a place for community members and businesses to access knowledge and equipment; it features cutting-edge, industrial-quality equipment and a space for people with similar interests to collaborate on ideas.

According to DNR, both of the drone prototypes are viable, but more refinement must be completed before the drones can be deployed in the field, and the department still needs to have more internal conversations about next steps for the process.

Picone was pleased with the trajectory of the project and the way it developed over the course of a year and a half. "The students were great in making it happen. And DNR was great in supporting it. Staff from DNR met with the students and asked them what goals they had for the next meeting. It was a good experience for the students to meet with a project manager and to have deliverables," he said. "It was a really successful project."

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