“An arm for a leg.”

No, the line is not part of a bargaining exchange. It’s the catchy title of Thomas Reilly’s research poster at RISE:2016.

Reilly, BHS’16, is devoted to making rehabilitative robots more sensitive and less cumbersome while retaining their strength. To those ends, the fifth-year physical therapy major has designed an electrically-powered robotic arm that can help people who have suffered spinal cord injuries, strokes, and other medical casualties learn to walk again.

The standard robotic offerings, says Reilly, comprise “gigantic metal panels,” or “exoskeletons,” worn on the leg, trunk, and upper extremities. The patient uses the device while on a treadmill and supported by a harness. Reilly’s invention, which also uses a treadmill and harness, comprises a simple robotic arm that attaches to a band on the user’s ankle.

Think mainframe computer transformed into MacBook Air.

“We wanted a robot that could mirror a human physical therapist,” says Reilly. “Sensitivity” is the key word. “The aim was for it to be able to sense when the person was ready to move a leg and to follow that lead with no interference.”

In the initial stages of rehab, Reilly’s robot would do much of the work, guiding the user through a natural heel-to-toe gait. But as the user gained mobility, he or she would become more self-reliant. “The impetus would come from the person, not the robot,” he says.