For their senior capstone design project, a group of mechanical engineering students created a prosthetic limb designed to help amputee agricultural workers operate tractors.

The prototype, dubbed the “farm arm,” features a prosthetic terminal device and set of adaptors that can be switched in and out to match the controls being operated. The design, the students said, eliminates the need for a grasping mechanism and can be universally used.

“Our design emulates where the hand would be at the point of interface with the tractor controls,” said Andrew Waite, E’15, one of five students comprising the capstone team.

Farm accidents are two and a half times more likely to end in amputation than any other injury, and 11 percent of all farm accidents involve amputations, according to the Farm Injury Resource Center. The students noted that, despite the high rate of amputation in the agricultural industry, prosthetic options often fall short in utility and durability. What’s more, workers in this industry are often geographically isolated, which makes fitting and training them for prostheses challenging, they said.

These factors inspired the students to design a solution: a prosthetic arm and adapter that are robust, ergonomic, adaptable, and can be easily used to engage throttle levers, hydraulic levers, joysticks, and steering wheels.

The students—Waite, Jacob Cohen, Carly Gajewski, Jonathan Leydon, and Daniel Walsh, all E’15—presented their design in December. Their prototype features an aluminum body, a titanium end piece, and 3-D printed adapters. Now they are refining their design, assessing manufacturing options, and exploring different paths for taking their device to market.

To properly frame their design for end-users, the students established and maintained constant contact with several prosthetics experts, industry leaders, and organizations that work with disabled farmers. Late in the project, this led to a key opportunity to test their device with a farmer in Rumford, Maine, who had lost part of his right arm. He used the “farm arm” on his own tractor, and then provided valuable feedback on what worked well and offered suggestions on how it could be improved.

“That’s when the project really came together,” Walsh said. “It provided a good opportunity for proof of concept and to validate our design.”

The students noted that their capstone project benefited from their co-op experiences. Walsh, for example, received regulatory training while on co-op at Johnson & Johnson, an experience that helped inform the group’s knowledge of how to bring their device to market. Cohen’s work on the capstone project focused primarily on materials research, which was informed in part by his co-op at NxStage Medical, where his work involved researching, designing, and working with parts for various medical devices. Gajewski, for her part, worked on co-op at the Center for Technology Development at Massachusetts General Hospital, where she got hands-on experience assembling a prototype for a novel medical diagnostics system. That work translated to her team’s capstone, for which she focused on the biomechanical aspect of the design process, examining factors such as the operator’s body motions in the tractor cockpit and the ergonomics associated with using the controls.

“All five of us drew from our co-op experiences for this project,” Waite said.