If the lion is the rugged SUV of the big cats, then the cheetah is more like a flashy sports car. These light, svelte predators will crumple under attack, but no other land animal can hope to catch them when they're moving at a full tilt. The cheetah has a lot to teach researchers about the mechanics of running, which is why a lab at MIT has developed a robotic version of the cat that now runs more efficiently than ever.
The robot in question weighs 70 pounds (more or less the same as a real cheetah), but unlike its wild cousin, this cat is more comfortable running at slow speeds over long periods of time. At present, the cheetah robot can run at 5 miles per hour for up to an hour and a half, a gait much more similar to its human creators than its biological cheetah forebears.
While other organizations such as the U.S. military have developed similar cheetah robots, this model is much more energy efficient. At present, MIT's cheetah cannot run as fast as the military's, but it can function for a longer period of time, with less net energy expended.
Other robots, such as Boston Dynamic's quadrupedal " Big Dog " and Honda's bipedal "ASIMO," have struggled with energy efficiency while running, limiting their potential usefulness in the field. MIT's researchers took a three-pronged approach to solving this problem: address heat loss from the robot's engine, reduce inertia in its legs and keep the impact of its feet on the ground to a minimum.
To keep the robotic felid running smoothly, the researchers installed a high-torque motor with fewer moving parts than a traditional setup. "With our system, we can make our robotic leg behave like a spring or damper without having physical springs, dampers or force sensors," says Sangbae Kim, an assistant professor in the department of mathematical engineering.
To address the robot's inertial issues, Kim and his team designed a hip joint to bear 85 percent of the leg's weight. They also reinforced the skeletal legs with Kevlar, which adds weight and stability to the system. The artificial cheetah's spine is also segmented like real vertebrae, which helps keep weight distributed as the automaton runs. [See also: 10 Animal-Inspired Robots ]
Unlike a real cheetah, which can reach speeds in excess of 70 mph, the robot will cap out around 35 mph once it undergoes its next series of upgrades. Still, the artificial cheetah's increased stability and ability to run for long periods puts its efficiency in the "real animal" range, behaving similarly to humans, hunting dogs and even its living, breathing cheetah brethren.
As robot technology continues to advance, having robots that can run quickly, stably and without tiring will prove useful. Whether future rescue robots will resemble cheetahs, humans or something else entirely is still a matter for researchers to investigate.
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