Local RoboCup playoff becomes demonstration rather than competition

Cornell student RoboCup team members prepare their soccer "players" for a demonstration in the Center for Theatre Arts' Flexible Theatre May 5, as audience members look on. Robert Barker/University Photography

By Bill Steele

A lot of engineering is trial and error. You build it, you test it, and if it doesn't work, you build it again.

The audience that came to watch the Cornell robot soccer playoffs on May 5 got a practical demonstration of that principle. They learned how soccer-playing robots work and met the students who designed and built them, but due to a technical glitch, they didn't get to see an actual game.

"It could have been a lot worse," said Raffaello D'Andrea, assistant professor of mechanical and aerospace engineering and adviser to the teams. "It might not have worked at all."

What was supposed to have happened was a competition between two teams of soccer-playing robots built over the past school year by two teams of engineering students. The results would determine, in part, which robots would go on to the World Cup of robot soccer, familiarly known as RoboCup, where some two dozen teams will meet in Melbourne, Australia, in August.

"We will probably take both sets of robots to RoboCup," D'Andrea said. One of the two teams worked with the robots that won RoboCup for last year's Cornell team, making a few improvements. The other team started from scratch, and came up with an innovative wheel design that allows the robots to scoot sideways or diagonally just as easily as forward and back, a definite advantage on defense. A few of each type of robot may be fielded as a single team, D'Andrea said.

Robot soccer -- in the "small" division in which Cornell competes -- is played on a field the size of a regulation ping-pong table by robots small enough that two teams of five can fit on the field; the ball is a golf ball. The robots are remotely controlled by a central computer with no human intervention. The game is a test of mechanical and electrical engineering skills in the design of the robots and programming skills in the design of the software that controls them.

An invited audience of about 200 people -- faculty, engineering alumni and friends of the student team members -- gathered in the Flexible Theater of the Performing Arts Center to watch the local playoffs. D'Andrea opened the proceedings by explaining robot soccer and introducing the students on each team. He emphasized the educational nature of the project by detailing what each student planned to do after graduation.

But the theater, deliberately chosen to accommodate a larger audience than was able to fit into the Phillips Hall lounge last year, turned out to be the undoing of the demonstration. In robot soccer, a video camera mounted directly above the field transmits a picture to a computer that analyzes it and finds the location of the ball and the players, relaying that to another computer that determines strategy and sends commands to the robots. The vision system must be set up each time it's used to allow for minor variations in the location of the camera relative to the field and variations in the color and placement of the lights. Because participants had little time to set up in the new location, one student explained, they didn't have time to do this properly.

As a result, the computer thought everything was 7 centimeters away from where it actually was. Robots frequently bumped into the wall around the field and attempted to kick empty air next to the ball. Nevertheless the students were able to explain some of the principles of the game strategy and show the audience how the robots could avoid obstacles and seek out the ball. A few younger members of the audience got to control robots directly using joysticks.

Several students will stay on campus over the summer perfecting the system and preparing for the World Cup. While the Big Red team hopes to win again, D'Andrea said, cautiously, that he expects the team to place in the top four. Last year Cornell literally walked away with the championship, previously held for two years by Carnegie-Mellon University. D'Andrea said he believes this was because other teams were made up entirely of computer scientists, while Cornell combined the talents of mechanical and electrical engineers with those of programmers.