This exoskeleton allows you to run twice as fast

Researchers have invented a spring-loaded exoskeleton that increases the running speed by 50% without a battery or an external motor. A light and portable device inspired by the bicycle pedal that could boost human performance in sports or the police.

Will we soon be able to catch a bike for running? This is the challenge launched by David Braun, professor of mechanics and computer science at Vanderbilt University, in the United States. With his students, he imagined a spring exoskeleton inspired by the dynamics of bicycle pedals. According to his calculations, this equipment would reach 18 meters per second, or nearly 65 km / h.

An exoskeleton inspired by the bicycle pedal

Numerous robotic exoskeletons have been developed to assist paralyzed people to walk again , help lift heavy loads or even relieve the weight of equipment in soldiers . They use actuators and external energy (motors and batteries) to increase human power. But none allows you to run faster without power supply.

”  As far as human speed is concerned , the bicycle has been the defending champion for more than a century, ” attests David Braun. If the bicycle makes it possible to reach speeds much higher than running, it is thanks to the invention of the pedal in 1868. Pedaling provides a triple advantage: it does not produce any loss of energy during the impact of the foot with the ground, partially supports the weight of the body and propels the cyclist continuously, unlike running where propulsion only takes place when the foot hits the ground.

Accelerate as you gain speed

To apply this advantage to running, David Braun and his team imagined an exoskeleton on springs that store energy during the thrust on the ground and release it when the leg is in the air. Unlike conventional springs, whose stiffness is constant and depends on the material, this variable stiffness spring sees its stiffness increase by shortening.

However, it is this rigidity which determines the force with which the runner pushes against the ground to accelerate the body: the stiffer the spring, the greater the propelling force for the same compression force . ”  Increasing the stiffness of the spring when the rider is gaining speed has the same effect as switching to a higher speed on a bicycle when the cyclist is riding faster,” explains David Braun. This allows runners to provide more energy and bypass the biomechanical limitation where energy is only provided during the short contact time on the ground of the fast race.