In research centers around the world, roboticists have for decades been on a quest to perfect bipedal locomotion in machines.

They’re making progress, but for all the flashy shots of back-flipping, log-hopping robots racking up views on YouTube, researchers say, there are far more failures and dead ends that the public never sees.

That’s because bipedal locomotion –– while extremely useful for moving humans up stairs, over mountains or across complex surfaces –– offers so little room for error in machines. While people can generally pick themselves up after falling over, taking our complex ability to regain balance for granted, researchers say, it’s still exceedingly difficult to design an upright walking robot that can do the same, especially as it moves across different surfaces.

Instead of creating more sophisticated computer programs to enhance robotic balance, researchers at Caltech’s Center for Autonomous Systems and Technology decided to bypass the issue altogether by removing gravity from the equation. The result is a newly-unveiled machine that they’ve dubbed Leonardo, which stands for “LEg ON Aerial Robotic DrOne.”

Part bipedal robot, part aerial drone, the hybridized machine was inspired by birds’ ability to move between flight and walking on two legs. Two powerful rotors on the machine’s torso allow it to leave the ground when it’s convenient or regain balance by using thrust to shift its weight as needed.

Leonardo is innovative because its design pushes back against the notion that a robot should be strictly land or air-based, according to Professor Morteza Gharib, director of the Graduate Aerospace Laboratories at Caltech, who co-developed Leonardo with Caltech roboticist Soon-Jo Chung.

“This is not a drone,” Gharib said, noting that the machine can fly, but it isn’t designed to do so at high altitude for long stretches of time. "The rotors attached to its torso kick in when basically it loses balance or when the robot needs to create stability.”

“We are very excited,” he added. “I can go and kick this one very hard, and it doesn’t fall over."

Aside from the satisfaction of bringing an ambitious idea to life, Gharib said researchers are even more excited about Leonardo because of the many possibilities the machine’s unique design could someday offer.

Gharib said he can envision the robot being used for inspections on oil rigs or wind turbines –– places where a bipedal robot could be useful, but at risk of falling. The machines could also be dropped from an airplane, perhaps in groups, to aid in search and rescue missions, he said. Future versions could also be used to navigate the harsh terrain found on other planets like Mars.

And unlike drones, he noted, having stabilizing legs means the robot would be able to carry heavier batteries, giving the machine more power and versatility.

“I can envision this robot helping a geologist when they go on out into the field,” Gharib said. “They’d be able to carry equipment and then fly overhead and take steady images, becoming a scientists or an engineer’s companion."

“There’s a perception that robots will take over the world and harm mankind, but our community is developing machines that will help society first," he added.

A video released by Caltech –– which has racked up more than 23,000 views –– shows the robot delicately balancing on a ledge, spinning on one leg and walking up and downhill using its “thrusters” for balance.

The current model is about two and a half feet tall and weighs less than 10 pounds, but Gharib said future models will double in size and grow increasingly fast and stable as machine learning algorithms improve the robot’s movement with more experience.

The Caltech team is certainly not the first to dream of creating futuristic machines with the ability to shift between different forms of locomotion.

At this year’s CES technology show in Las Vegas, Hyundai introduced a concept car designed to walk as easily as it rolls. Called “Elevate,” the daddy-long-legs-like machine has wheels at the end of long robotic legs that would allow “users to drive, walk or even climb over the most treacherous terrain,” according to the company.

The company — which labeled the machine a UMV, or “ultimate mobility vehicle” — said the concept was inspired by the need for “resilient transportation” in disaster zones, where conventional vehicles are often rendered useless.

“When a tsunami or earthquake hits, current rescue vehicles can only deliver first responders to the edge of the debris field,” John Suh, Hyundai vice president and head of Hyundai CRADLE, said in a statement on the company’s website. “They have to go the rest of the way by foot. Elevate can drive to the scene and climb right over flood debris or crumbled concrete.”