Researchers at MIT are developing a cheetah robot that’s as efficient as its natural counterpart. Using special motors and regenerative energy systems, the robot is highly efficient.
Other four-legged robots, like Boston Dynamic’s [terrifying] Big Dog and Alpha Dog use heavy gasoline engines and employ hydraulic transmissions to move their legs. And while Boston Dynamic’s robots are very capable machines, these systems waste a lot of energy. Robots that can walk also require countless gears, springs and force sensors in their legs and joints to achieve locomotion. And to work autonomously, electric robots require large, heavy battery packs to power their functions.
Esther and Harold E. Edgerton Assistant Professor Sangbae Kim, of the Department of Mechanical Engineering at MIT, said that for any real practical application, walking robots need to be more efficient.
“In order to send a robot to find people or perform emergency tasks, like in the Fukushima disaster, you want it to be autonomous,” Kim said. “If it could run for more than two hours and search a large field, that would be useful. But one of the reasons why people think it’s impossible to make an electric robot that does this is because efficiencies have been pretty bad.”
Kim and a team of researchers have developed an electric, 70-pound, cheetah-shaped robot that features greatly improved efficiency.
“With our system, we can make our robotic leg behave like a spring or damper without having physical springs, dampers or force sensors,” Kim told Phys Org. The cheetah’s legs also regenerate some of the energy lost whenever it strikes the ground. “The majority of impact energy goes back to the battery because the damping is created by custom-designed electric control of the motor. [The motor] regenerates energy that would have been lost.”
In addition to energy regeneration, the team also installed high-torque-density motors that create more torque than commercially available electric motors.
Currently, the robot can trot along on a treadmill at 5 mph for about as long as some high-efficiency hunters, like actual cheetahs, hunting dogs and humans (one of the world’s most efficient terrestrial animals when we’re not eating cheeseburgers and watching TV). The researchers anticipate the cheetah robot being able to run at up to 35 mph once the team installs new motors into the robot’s legs.
“There are so many ways to design, and each legged robot has a different system,” Kim said. “If you design the motor properly, it’s more powerful, simpler robotics.”