According to Oregon State University (OSU), research into how humans have been walking for more than a million years may yield some of its earliest applications in improved prosthetic limbs. The findings which appear in the Journal of Experimental Biology highlight a specific interaction between the ankle, knee, muscles, and tendons that could improve the understanding of a leg moving forward in a way that maximizes motion while using minimal amounts of energy.
Jonathan Hurst, PhD, OSU professor of mechanical engineering and expert in legged locomotion in robots, designates human walking as, “extraordinarily complex and we still don’t understand completely how it works.”
The university notes in a news release that in the past, researchers have observed a type of higher-power “push off” when the leg leaves the ground, yet did not understand how it worked. The current study indicates that there two phases in this motion; the first being an “alleviation” phase during which the trailing leg is relieved of the burden of supporting the mass. Next, the “launching” phase sees the knee buckle, allowing for the rapid release of stored elastic energy in the ankle tendons.
Daniel Renjewski, postdoctoral research associate, Dynamic Robotics Laboratory, OSU, notes that once researchers calculated what the muscles could do and found it “insufficient” for generating a powerful push off, they focused on finding a power-amplifying mechanism.
“The coordination of the knee and ankle is critical. 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,” Renjewski adds.
The OSU release reports that walking robots do not do this and instead, use force to “swing” the leg forward from something resembling a hip point. Hurst acknowledges that the researchers have a “long way to go before walking robots can move with as little energy as animals use. But this type of research will bring us closer to that.”
The release also states that robots with the ability to walk and maneuver over unseen terrain could also hold promise in a variety of applications including in prosthetic limbs, an exo-skeleton to assist individuals with muscle weakness, and use in the military.
Read the full study here