walking feet
January 18, 2014

Researchers Reveal The Mechanisms Behind Walking, Could Lead To Better Prosthetics And Robots

Brett Smith for redOrbit.com - Your Universe Online

Before most humans turn one year old – walking appears to be a complete mystery. However, not long after we take our first steps, walking around becomes a mundane mode of transportation we rarely give a second thought to.

Now, researchers from Oregon State University have found a unique interaction between the ankle, knee, muscles and tendons that reveals how a leg moving forward during walking maximizes motion while using the smallest amounts of energy – according to a report published last month in the Journal of Experimental Biology.

The study team said their findings could be used to improve prosthetic limb technology. They added that further research could lead to more agile and energy-efficient walking robots than those in use today.

“Human walking is extraordinarily complex and we still don’t understand completely how it works,” said Jonathan Hurst, an OSU professor of mechanical engineering.

“When we fully learn what the human leg is doing,” Hurst added, “we’ll be able to build robots that work much better.”

Previous studies have described a high-power “push off” when the leg leaves the ground, but haven’t been able to outline a mechanism behind it. The new study describes two phases to this motion: an “alleviation” phase and a “launching” phase.

During the alleviation phase, the weight of the body is removed from the trailing leg. During the launching phase, the knee bends and allows the quick release of stored energy in the ankle tendons.

“We calculated what muscles could do and found it insufficient, by far, for generating this powerful push off,” said Daniel Renjewski, a postdoctoral research associate in the Dynamic Robotics Laboratory at OSU. “So we had to look for a power-amplifying mechanism.”

“The coordination of knee and ankle is critical,” he said. “And contrary to what some other research has suggested, the catapult energy from the ankle is just being used to swing the leg, not add large amounts of energy to the forward motion.”

The OSU researchers noted that conventional walking robots swing their leg forward from a hip-like joint. This mode of walking is neither energy-efficient nor nimble.

“We still have a long way to go before walking robots can move with as little energy as animals use,” Hurst said. “But this type of research will bring us closer to that.”

In December, NASA announced it had built legs for its robonaut currently onboard the International Space Station, dubbed R2. Currently attached to a support post, the R2 robot arrived on the ISS back in February 2011 and has been performing a series of tasks to test its functionality in a microgravity environment.

“NASA has explored with robots for more than a decade, from the stalwart rovers on Mars to R2 on the station,” said Michael Gazarik, NASA’s associate administrator for space technology in Washington.

Funded by NASA’s Human Exploration and Operations and Space Technology mission directorates, the mechanical climbing legs are expected to provide R2 with the mobility necessary for helping with simple and repetitive tasks both inside and outside the space station. NASA said it hopes to eventually use the “robonaut” to free up the crew for conducting scientific research projects.

Image 2 (below): New research at Oregon State University has created a better understanding of how humans walk with such agility and energy efficiency. Credit: Daniel Renjewski, Oregon State University