Spaceflight Now: Breaking News

NASA leaping into the future with robo-frogs
Posted: November 29, 2000

A small hopping robot with froglike abilities that moves by a combination of rolls and hops to its desired destination may someday hop a ride to an asteroid and leap its way to other planets in the search for water.

The frogbot, featured as the "robot of the month" in the Robot Watch news section of Discover magazine's December issue, weighs in at 1.3 kilograms (3 pounds) and is powered by a single motor. It is equipped with a camera, solar panels, sensors and onboard computer that executes commands autonomously, making the robot ideally suitable for exploration of distant planets, comets and asteroids.

Froglike robot. Photo: NASA/JPL
Under development jointly by NASA's Jet Propulsion Laboratory and the California Institute of Technology, both in Pasadena, Calif., the frogbot can steer and right itself.

"Hopping is a more efficient form of transportation in low-gravity environments," said Dr. Paolo Fiorini, an engineer in the robotics group at JPL. "Our hopping robot performs much like a frog, except that it only has one leg and no tongue. It has a spring between its knees that makes it bend its legs and hop. When the spring releases, the frogbot takes a 1.8-meter (6-foot) hop on Earth, which could become a 6-meter (20-foot) leap under low-gravity conditions on planets like Mars, depending on terrain."

Engineers believe that in low-gravity environments, such as small planets, and in micro-gravity environments, such as asteroids, wheels successfully used on rovers may not be the most efficient form of locomotion. In laboratory experiments, slithering, rolling and hopping have been shown to be alternative methods of propulsion.

In the future, NASA envisions missions involving dozens of small robotic vehicles. "To be effective, a small exploratory robot vehicle must frequently go over obstacles that are many times its body size," said Joel Burdick, the Caltech co-inventor of the robot. "Hopping or leaping motions are some of the few effective ways for small vehicles to overcome such relatively large obstacles."

"Our goal was to come up with a locomotion method and design that would use a minimal number of instruments and that would be small, compact, lightweight and still be able to perform useful scientific study," said Dr. Neville Marzwell, head of the Advanced Projects Office at JPL. Researchers at Sandia National Laboratories in Albuquerque, N.M., have also developed a hopping device, with more limited maneuverability.

The frogbot has shown better mobility than rovers on certain terrain. It can be developed to reach canyon walls and other remote areas, be manufactured at a lower cost and multiple numbers of the device can be released onto a planet's surface to cover large distances and communicate with each other. One frogbot could be lost without hindering the whole network.

The hopping robot technology will be ready in about three to five years and could help scientists capture images and collect ground samples. One of the major challenges facing engineers is precision navigation necessary to control the hopping robot. Engineers are also developing a hopper that adheres and climbs vertical walls and are testing prototypes on different ground terrains.

The Advanced Projects Office of Space Flight at NASA Headquarters is the primary source of funds for this work, which was also sponsored by a National Science Foundation grant through the Center for Neuromorphic Systems Engineering at Caltech. Managed for NASA by Caltech, JPL is the lead U.S. center for robotic exploration of the solar system.