Researcher takes a muscular approach to robotics

An active orthotic device developed by a Carnegie Mellon University roboticist uses soft materials and mimics the leg's structures for controlling the ankle 

Credit: Carnegie Mellon University

During his childhood in Korea, Yong-Lae Park developed a love for robotics, using the nuts, bolts and metal bars from science kits to build mechanical versions of his favourite cartoon characters.

"Robotics is very interesting and attractive because you build it and it moves on its own," Park said.

Today, Park, an associate professor at Carnegie Mellon University's Robotics Institute, retains his childhood passion but directs it toward more mature creations.

He's part of a team that has designed a robotic device to restore movement for sufferers of neuromuscular disorders that affect the foot and ankle, such as cerebral palsy, multiple sclerosis and drop foot.

The device, which looks like a sock made of cybernetic muscle sinews, uses pneumatics to augment the strength of patients' ankles.

While most such devices are bulky, this one eschews a rigid exoskeleton in favor of more nimble materials that could allow more flexibility.

Bor-rong Chen

Park's role in the eight-member team was to create the mechanical design and synchronize it with the muscle motions of the patient, said Bor-rong Chen, who worked on the device with Park while they studied at Harvard.

"He's a brilliant maker in general, with a very strong background in using the right material to solve a mechanical problem and designing the structure of the material," Chen said.

To design the device - a three-year effort funded by Harvard's Wyss Institute for Biologically-Inspired Engineering and the National Science Foundation - Park had to delve outside his robotic comfort zone, educating himself on the biology of the ankle.

Most exoskeletons treat the ankle as if it has only one range of motion, up and down, Park said. But when he studied the joint he realized that its movement was much more complicated. To mimic natural ankle movements, the device would have to account for this complexity.

After this realization, Park set about the formidable task of translating those complex movements into mechanical processes.

"My job is engineering, so I try to simplify those things as much as possible," Park said.

More information: iopscience.iop.org/1748-3190/9/1/016007/article