Five North­eastern Uni­ver­sity student-​​researchers have retro­fitted a rowing machine with an inge­nious device, allowing people with para­plegia to exer­cise without the aid of a trainer.

The mod­i­fied ergometer, dubbed the “power row,” was designed for a senior cap­stone project under the direc­tion of Sandra She­fel­bine, an asso­ciate pro­fessor of mechan­ical and indus­trial engi­neering. Team mem­bers com­prised Mar­garet Bergson, Robert Grif­fith, Jenna Hor­mann, Chris Parfitt, and Nikita Shah, all E’15.

The group recently filed a pro­vi­sional patent on the device, which has drawn interest from Concept2, the leading man­u­fac­turer of indoor rowers. “A device like ours does not cur­rently exist in the market,” said Shah, who recently grad­u­ated with her Bach­elor of Sci­ence in Mechan­ical Engi­neering, “and it is in demand by both people with para­plegia and their trainers.”

The project grew out of a problem-​​solving meeting between the young engi­neers and the phys­ical ther­a­pists at the Spaulding Reha­bil­i­ta­tion Hos­pital in Boston. The problem, the phys­ical ther­a­pists told the stu­dents, was that some two dozen patients living with a med­ical con­di­tion known as spastic para­plegia lacked suf­fi­cient motor con­trol of their legs to return to the starting posi­tion after taking each stroke on their rowing erg. Trainers had to push patients for­ward using the handle bar on the back of the their seat, applying up to 130 pounds of force to over­come their inability to flex their legs. The solu­tion, both par­ties agreed, was to design a motor­ized device that would allow the patients to exer­cise in their own homes without a trainer’s assistance.

The engineers-​​in-​​training got to work, devel­oping three poten­tial design con­cepts. The one they chose to turn into the pro­to­type uti­lizes a gear system to trans­late torque from a brush­less ser­vo­motor to a cap­stan, which moves the seat.

The design, the stu­dents wrote up in their project report, offers two key advan­tages over the other poten­tial schemes. First, the device remains under­neath the erg, which allows the system to operate without inter­fering with the rower’s workout. Second, the ser­vo­motor allows for flex­i­bility in speed and torque, which can be changed based on the size and ability of the rower.

It won’t be long, the stu­dents say, before patients at Spaulding begin using the retro­fitted rowing machine and passing along their feed­back. Even­tu­ally, they note, they’ll want to modify more ergs for the facility, the man­u­fac­turing cost of which would be approx­i­mately $100 per machine.

We’re really proud of what we’ve accom­plished,” Shah said, “but we also want to see this work through and solve this problem.”

Her engi­neering strategy, she noted, was informed by her sta­tics and mate­rials sci­ence class­work at North­eastern as well as her co-​​op expe­ri­ence with a trio of cutting-​​edge com­pa­nies in the med­ical device and ortho­pe­dics fields.

I learned things on co-​​op that I could never have learned in class,” Shah explained. Pointing to her pro­to­typing projects with Boston Sci­en­tific, she added, “I devel­oped a new level of cre­ativity from having to figure out how to make things work.”

She­fel­bine echoed Shah, saying that cap­stone projects rep­re­sent the cul­mi­na­tion of five years of hard work both in class and on co-​​op. “Cap­stone forces stu­dents to put together every­thing they’ve learned in order to build some­thing new,” she said.