Making humanoid robots that can stretch and sweat

Standard axial-driven humanoid robots, such as Asimo (known for playing soccer with President Obama) or HRP-2(which competed in the DARPA Robotics Challenge in Pomona in 2015), have far fewer joint degrees of freedom: around 27 to 55, the authors write.

But tendon-driven robots like them, with their human-inspired musculoskeletal structures, have about double that, from 55 to 114 joint degrees of freedom. Kenshiro has 64 degrees of freedom, thanks to multiple spine joints (structured in a human-like S-curve) and a more humanoid knee joint. Kengoro has 114 degrees of freedom-or 174, if you include all the joints in its hands.

Kengoro does have fingers and toes, but they still have a way to go to match the musculature of human digits, the authors write. Given how important these "end effectors" are to human life, improving those is key, they say.

"End effectors are important for humans in their daily lives," the researchers say. "This suggests that it is essential to develop human mimetic end effectors to move humanoid robotics forward."

The researchers even designed Kengoro to sweat, developing an artificial perspiration system to release heat from the motors.

The scientists say incorporating these kinds of humanoid characteristics could help reveal the invisible inner workings of human bodies-and find better ways to prevent and treat illness and injury.

"One research group has suggested the possibility that a musculoskeletal humanoid can be used in medicine, such as to grow tissue grafts," the scientists point out. "If a humanoid can replicate human movements, then the resulting muscle contribution analysis or sensory data obtained during motion will benefit athletes or sports trainers."

That kind of data could also be useful for developing better artificial limbs or designing tele-operated human agents, they add.

It could even make crash dummies more "active" participants in experiments, incorporating the ways that human bodies react during accidents and making those tests far more accurate.

"An interesting application is active crash test dummies used during car crash testing, because current dummies can only measure passive behavior," the authors write. "A human mimetic humanoid enables the replication of human reflective behavior by muscle actuation."

Tribune News Service