Outside of fiction, robots are rarely bipedal. If a robot has legs at all, it’s likely to have at least four of them, providing a range of balance and stability replicated often in the animal kingdom. On wheels or tracks, the robots’ movement becomes even more familiar, the chassis of a vehicle reproduced in miniature. When two-legged robots exist, they can struggle with balance, requiring careful design to navigate spaces and weight shifts that come naturally to humans. Which is what makes the SALTO robot so intriguing: rather than walk on two or more limbs, SALTO bounces and balances on a single foot attached to a single leg.
“SALTO” stands for “saltatorial locomotion on terrain obstacles,” and the one-legged machine draws its direct inspiration from the small Galago primates of sub-Saharan Africa. Galagos are built to jump multiple times in rapid succession, and SALTO is never not jumping when it moves, a powerful leg constantly propelling it forward and upward.
SALTO was built by researchers at the University of California, Berkeley with funding from an Army Research Grant. Novel movement schemes and patterns could prove useful in finding and rescuing people after disasters in collapsed buildings, and SALTO’s small form means it could travel through spaces before them become accessible to humans. The robot is capable of leaping up to 4 feet, and can perform hundreds of jumps over a 10 minute span. It is like a character in a platformer video game brought into reality, bounding from surface to surface and stringing those leaps together to clear obstacles and move from surface to surface.
The SALTO project has gone on for years, first demonstrating successive leaps in 2016. In 2016, stopping moving was the trickiest part, with the robot often ending its series of leaps by falling into a net. Recent advancements added stability controls, like counterbalances and little rotors and internal sensors, which allow the robot to move outside the lab under the remote control of a human operator, but the landings are still tricky.
If a future SALTO-inspired military rescue robot is designed to look for somebody, falling in place once it identifies a human in need should be plenty fine, especially of the robot can be adapted to carry a walkie-talkie or another signalling tool, alerting human controls as to what it found. Putting a useful sensor package on the robot could make it a scout that could travel inside spaces too small and irregular for humans, perhaps bouncing into chimneys or through pipes or over rubble.
Before any of the planning into missions can take place, the robot will need to travel over new and diverse terrain. For now, its pogoing motion works best on cement, wood paneling, and in the lab. Adding dirt, grass, and rocks to the features it can bound over will greatly expand where SALTO can go, and what can be done with in.
In the meantime, it’s worth thinking about the possibilities a platform like this opens up for rescue and reconnaissance work. The robots of tomorrow’s battlefields will likely be far stranger than fiction has imagined.
Watch SALTO in action below: