Minerva the robot began guiding tours this week at the American Museum of History. But unlike the testy rolling computer from the movie Star Wars (on display at the National Air and Space Museum, another Smithsonian Institution museum), Minerva is user-friendly.

"It finds people, is going to approach them and ask them whether they would be interested in a tour," said Sebastian Thrun, head of an international team from Carnegie Mellon University and the University of Bonn that developed the robot.

"The prototype robot is able to learn about its surroundings and adapt to new situations," Thrun said.

An on-board computer and sensors that use infrared lights to measure distances help Minerva navigate and map its environment. According to Thrun, Minerva avoids collisions much the same way bats do: by sending out sound waves and measuring how long the echo takes to bounce back.

"It starts exploring its environment and learns a floor plan," Thrun said. "This enables it to find its place and then to find people."

The robot's job is to guide visitors through the "Material World" exhibition of artifacts that illustrate how materials have influenced the way humans live.

Minerva explains how robots fit into the history of these items. At one exhibit, Minerva explains how a clock functions but points out it cannot make decisions like a robot.

For those unable to travel to Washington, built-in cameras that double as Minerva's eyes will allow computer users to take a tour from home on Thursday night.

Minerva is a squat, compact robot resembling a gray version of R2-D2. The robot's red mouth and blue eyebrows both move, depending on its mood.

Minerva likes humans and responds to people touching its screen by saying: "Oh, that tickles." It even complimented an underdressed reporter. "I love your T-shirt," Minerva said in its soft human-like voice.

"When people approach it, Minerva starts smiling," Thrun said. "I would say it's a happy robot -- when its path is blocked it says 'Excuse me'."

But the designers also added a touch of attitude. Minerva frowns when people crowd its space and blows a horn to get people to move. This is largely a safety precaution because Minerva cannot maneuver when its path is cluttered.

Hordes of people trying to disturb the robot, though, will actually help the researchers, Thrun said. The new surroundings will allow the team to see how people interact with robots and how Minerva responds when disturbed by visitors.

"This is the perfect environment for us," Thrun said. "There is no better place than this museum to test it."

Minerva cost about $30,000 to develop, but since technology is rapidly becoming better and cheaper, a similar robot, according to Thrun, will only cost a few thousand dollars in three years.

During the tours a designer will be on hand to answer questions and make sure Minerva performs well during its stint as a guide, which ends on Sept. 5.