Doggone good engineering

When it came time for mechanical engineering student Hiromi Tsuda to pick a senior capstone project, she knew that she wanted to tackle something that would improve dogs’ quality of life. 

It didn’t take her long to find a worthy problem. After researching animal prosthetics online, Tsuda learned that while prosthetics for dogs are widely available, most require the animal to have a certain segment of a limb remaining. That leaves three-legged animals like central Ohio pooch Jimmy—a puppy mill survivor whose right leg was amputated at the shoulder joint following an injury—without many options for improved mobility.

A Columbus Dispatch story about Jimmy’s plight was one of the first search results that popped up during her research, Tsuda said. As much as she wanted to help the brown-eyed, shaggy-haired cockapoo, she first thought that creating a prosthetic for him would be too challenging. But after reaching out to Jimmy’s owner, Susan Montgomery, and hearing about the increased difficulty he had getting around, Tsuda knew she had to try.

“Susan was just so enthusiastic and passionate about Jimmy that it captured my heart and I thought, ‘I have to do it. I have to try.’ Especially because nobody else out there has been able to succeed,’” said Tsuda. “I thought, ‘if I can at least make that first step, even if I fail, maybe somebody else can pick it up and make it better.’”

After successfully pitching the project idea to mechanical and aerospace engineering capstone course instructors Anthony Luscher and Joe West, Tsuda and six other dog lovers split into three teams based on expertise and got to work researching, analyzing, designing and fabricating the novel prosthetic. The project team included fellow mechanical engineers Erin Dennis, Brandon Elias, Nate Huntsberger, Graham Lyon, Lawrence Miller and Marion Ross.

Ohio State veterinarians and faculty from across campus lent their expertise and equipment to help the students be successful. Dr. John Dyce, associate professor and head of orthopedic surgery at Ohio State Veterinary Medical Center, provided technical advice throughout the project and funded a complete CT scan of Jimmy. The scan showed evidence of arthritis in the dog’s left leg and possibly his back, as well as low bone density in his scapula. 

The students combined the 841 CT image slices into a 3-D model of Jimmy’s skeletal and muscular systems. Using motion capture testing, they studied the kinematics of how Jimmy’s joints move and used a Tekscan mat to measure and map the pressure distribution of his movements.

After gathering all of the initial data, the team chose a hard chest plate harness for Jimmy, Tsuda explained, which distributes support across his body and provides a solid structure for attaching the prosthetic leg.

The students then went the extra mile, literally, making two trips to Animal Orthocare in Virginia where President and Certified Orthotist Derrick Campana shared his expertise in creating animal prosthetics and created a thermoplastic harness for Jimmy. 

For the prosthetic leg that actually attaches to the harness, the team created a system of linkages combined with a spring system and a blade style foot.

“The unique thing about our design is our spring system. It’s what makes our leg move forward once Jimmy has pressed up all the way against it,” Lawrence Miller explained.

The project also provided a unique outreach opportunity when Montgomery invited all seven Buckeye engineers to present the project and its related engineering lessons to her eager class of fourth- and fifth-grade students, as well as two local TV news crews. [watch the classroom visit via WNBC-TV New York and WSYX-ABC 6 Columbus]

But like many engineering capstone projects, the enormity of the task they tried to solve in just one and a half semesters weeks tested Tsuda and her peers. 

“I learned is that as team leader it’s difficult to coordinate a big group, but I realize that with good teamwork you can get a lot accomplished,” she said. “We only had 10 weeks, but we did a lot of research and were able to accomplish so much. I’m very proud of us. Mimicking a biological system is very difficult and we learned that firsthand.”

The students’ hard work was rewarded when they fitted Jimmy with the prosthetic for the first time and watched as he calmly balanced and walked on it, with a little assistance from his new human friends.

“It was amazing, I could feel him wanting to try it,” said Tsuda after carefully helped Jimmy walk with the prosthetic for the first time. “I almost cried.”

As the capstone project officially ended in early June, the team had a list of improvements they wanted to make, including adjusting the angle of how the leg connects to the harness and improving the tread of the metal foot to provide more traction on slippery surfaces. They also wanted to fabricate a new leg out of reinforced carbon fiber titanium, instead of the current aluminum, which would greatly reduce the prosthetic’s current weight of about two pounds and make it easier for Jimmy to use long-term. 

Instructors Luscher and West are so vested in the effort that they committed to improving the prosthetic over the summer so that Jimmy can use it on a trial basis, although he’ll likely need physical therapy to take full advantage of his new four-legged freedom.

“The team has some great, innovative ideas and gathered a great deal of necessary information on how to create the leg,” said Luscher, associate professor of mechanical and aerospace engineering. “We will create the first trial for Jimmy this summer and will have future teams continue to improve the design.”

While the adorable Jimmy took the project in stride, the experience of working together to make his life a little easier made a lasting impact on his owner and the Buckeye engineers.

“The work they’re doing is phenomenal, to take this, collect all the data that they had, and then to be able to take that data and put it into this prosthetic leg is incredible,” said Montgomery. “The students have been absolutely fabulous. They’re compassionate, super intelligent people. It has been a gift for us to be able to work with them.”

by Candi Clevenger, College of Engineering Communications, clevenger.87@osu.edu