Professor, students develop innovative space-exploring robot without funding

Arizona Summer Wildcat UA professor Kumar Ramohalli shows off his new robot design. He hopes that the robot will be used for planetary exploration.

With their own money and spare time, a UA professor and his students have developed the first robot that uses artificial muscles to move its legs.

The Biomorphic Robot with Distributed Power, BiRoD for short, is the brainchild of Kumar Ramohalli, a University of Arizona aerospace and mechanical engineering professor.

Although they were unable to get funding for their project, the engineers chipped in and built the robot for about $500.

"I put in a lot of time on weekends," said Ramohalli, who led the year-long project.

The robot is "a quantum leap beyond what is current," said Doug Streibich, a UA aerospace and mechanical engineering senior. Streibich did much of the design work and construction.

The lack of funding led him and other students to be creative. Spare parts in the department machine shop were converted into the robots legs. An infrared sensor from a toy kit was used for the robots eye.

Ramohalli hopes to use BiRoDs to someday explore distant planets and asteroids.

Instead of the usual complex system of gears and servos, the robot uses "muscle wires" to move its limbs.

The wires are made of Nidinol, a compound of nickel and titanium. Like real muscles, the wires constrict when an electric current runs through them. When the current is shut off, the wires relax. Wires can be bunched together to make stronger muscles.

"They are the size of a human hair and they can lift thousands of times their own weight," Ramohalli said.

This robot uses infrared and ultraviolet sensors that enable it to see in complete darkness. In an innovative step, the designers used wire muscles instead of gears to move the legs.

Ramohalli and his students have built a nearly full-sized prototype that measures 10 inches long and five inches wide. It stands eight inches high on a pair of front legs and two back legs that were fitted with wheels. The muscle wires make the front legs walk, pulling the rear legs along behind.

The muscle wires can perform many of the tasks of real muscles, such as gripping and storing up energy for sudden bursts of strength and speed.

The BiRoD is not the only robot to imitate nature. Scientists are developing mechanical insects to explore caves and collapsed buildings, and the army is working on artificial flocks of birds that would detect and clear minefields.

On the front of the BiRoD is a small head with infrared and ultraviolet sensors that allows the robot to navigate rough terrain in complete darkness. An electronic brain would allow it to avoid large obstacles.

"If it comes across any bad obstacle, it tries to lock one limb so it will turn," he said.

The body itself is empty except for a few wires. The extra space can be filled with scientific equipment and power packs, he said.

The BiRoD weighs less than three pounds, making it cheap to launch into space, Ramohalli said.

Up to 25 BiRoDs could be launched using the same space and weight as the more traditional robot used for the Mars Pathfinder mission. Once on Mars, they would be able to spread out and explore a large area, he said.

Ramohalli estimates that it costs about $5,000 to launch one pound into orbit, and more if it is going further out to a planet. Such prohibitive costs have led many engineers to develop lighter materials and instruments for space exploration.