Duke Robotics Club Takes 2nd Place in Underwater Competition

Persistence paid off for Duke student members of the Robotics Club at the 9th International Autonomous Underwater Vehicle Competition held in San Diego, Calif., from Aug. 2-6. Their enhanced version of the robot “Charybdis” took second place and $5,000.

Twenty undergraduate teams and one high school team participated in the event, which is sponsored by the Association for Unmanned Vehicle Systems International and the Office of Naval Research. The challenge involved four tasks: pass through an underwater gate, dock with a light beacon, follow a pipe located on the pool bottom and drop a marker into a bin, and then detect acoustic signals in order to surface in a designated recovery zone.

This was the third year that the Duke robot participated in the competition. The latest incarnation of Charybdis was the first to include hydrophones capable of listening for the surfacing signal. The new and improved submersible also included an improved line-following algorithm to better track the pipeline.

Earlier versions of the robot took fourth place last year and Most Innovative Design in 2004, its debut year.

The spherical, Duke-blue Charybdis is distinguished by its symmetrical design, which provides greater control, said Brian Hilgeford, who graduated in September with a degree in mechanical engineering, in an interview the week before the competition. The torpedo-shaped robots of many other teams are typically capable of greater speed, but poorer precision, he said.

The student team members went into this year’s competition feeling confident about their chances.

“Experience is important,” said junior Gareth Guvanasen, a double major in electrical and computer engineering (ECE) and computer science. “Very rarely do schools do well in their first years because of the steep learning curve.

“It can be hard to get even one aspect of the robot to work,” he added.

The team had anticipated at least a top four finish if the hydrophones worked properly--top two if everything went according to plan.

“But it all comes down to what happens at competition,” Hilgeford said.

Indeed, the team had several tense moments at the competition when a "mysterious bug" left Charybdis intermittently unable to recognize its "Doppler Velocity Logger" (DVL), a sonar device that allows the robot to track its location and velocity.

They managed to diagnose the problem just before the second and final qualifying round as a poor serial connection. After some hurried repairs, Charybdis performed beautifully and made it to the finals.

"In our minds we had gone from last to second place within twenty minutes and we all learned that it truly pays to never get discouraged in times of adversity," Guvanasen said.

First prize and $7,000 went to reigning champions from the University of Florida. The Florida team's robot completed essentially the same tasks, but pulled ahead of Duke in the rankings due to its lighter weight, said club adviser Jason Janet, adjunct associate professor in the ECE department.

"Duke's AUV carries a DVL for deadreckoning," Janet said. "This gives Duke's AUV greater utility, but doubles its weight.

"As competitions increase in complexity, or as Charybdis fulfills R&D roles for Duke faculty and staff, the value of this DVL will be obvious," Janet added.

In addition to Guvanasen and Hilgeford, the core team of Duke students involved this year included junior ECE and computer science major Andrew Waterman, mechanical engineering junior David Klein and biomedical engineering and ECE junior Jack Tao.