Student-Built Exoskeleton Mimics Human Knee

Bionic Legs
The prototype is far too bulky at the moment, but future iterations are to be much more streamlined. Reuters

Powered exoskeletons can give paraplegics or those with lower-limb weakness the ability to walk again, but they often struggle adapting to uneven terrain or coping with unexpected obstacles. Now, mechanical engineers from ETH Zurich believe they have the solution: an exoskeleton that more accurately mimics natural knee gait.

"Here with the Varileg we implemented the mechanical variable impedance, which is something special that no other exoskeleton has implemented at the moment," says Patrick Pfreundschuh, a mechanical engineer with ETH. "The advantage of this is that we can mimic the human-like stiffness adaptation of the human knee and this also allows us to adapt to unexpected obstacles because we can say how stiff the knee should behave."

The VariLeg design, the engineers say, continuously changes the knee stiffness so it can adapt to irregular surfaces or obstacles. The team at ETH also is planning to develop "smart crutches" that will act as a control to adjust the device for different situations.

"On the crutches we will have several buttons, and with these buttons he can decide where he's going and also to change the modes; so we will have straight-walking mode, and stairs mode and sit-down mode," says Pfreundschuh. "So he can change between the modes and then tell the device what it should do."

This proof of concept prototype is, admittedly, far too bulky, but the team is already hard at work building the VariLeg 2, a much more streamlined and lightweight design.

That's still someway off. For now, they're working on perfecting their system, but it's a step in the right direction.