Penn engineering students design robot that plays the sitar—sort of
Candace diCarlo
Robots have been designed to do all kinds of things, from vacuuming floors to welding car bodies to helping surgeons repair heart valves. Last year, four mechanical engineering students at Penn set out to see if they could design a robot that would play music like a sitar player.
RAVI-Bot, the senior design project of Peter Brueckner, Kristin Condello, Michael Dugan and Will Jelliffe, is an electromechanical, robotic sitar that emulates the improvisational style of the Indian stringed instrument. RAVI-Bot is currently on display at the Esther M. Klein Art Gallery at the University City Science Center as part of ArtBots 2007, an international robotic talent show held this year in Philadelphia.
As Condello explains, the idea for RAVI-Bot—named to honor world-famous musician Ravi Shankar—didn’t materialize out of thin air. She and her three co-designers were taking a robotics class in their junior year. “Peter [Brueckner] was taking Indian music classes at the time,” she says, “and he was really into it. We started joking about making a robotic sitar player.” The joke turned into a plan and, with the help of professors Vijay Kumar and Mark Yim, RAVI-Bot—or Robotic Audio Vehicle for Improvisation Robot—was born. The team members were particularly taken with the improvisational nature of sitar music, which they discovered was far from random. “The thing that’s cool,” says Condello, “and the thing that makes it easy to do as a robot is that in sitar music there are rules about which notes can be played after other notes. So we switched that over to programming—if I play B what notes can I play after that?—and were able to have it improvise [like] an Indian sitarist would improvise.”
RAVI-Bot looks nothing like a sitar, or a sitar player, for that matter. Instead, it consists of a simple plywood frame with three shelves. Ten cylinder shaped electric conductors called solenoids are grouped on the top shelf above a single tightly stretched metal string, with tuning pegs at one end, a motor and plucker at the other. Below sit more strings, along with two motors and additional pluckers. The solenoids, explains co-designer Will Jelliffe, work just like a finger, pressing down the string which the motor-driven plucker then plucks. “The motor is so quick we can go beyond the capabilities of human plucking,” says Jelliffe.
The circuit boards, loaded with programming the team designed on a computer, are the “brains” of the robot, driving the motors and solenoids and “telling” the instrument how to proceed musically.
“The RAVI-Bot was an immense multidisciplinary project,” says Brueckner, and his fellow team members agree. Though they all had expertise in mechanical engineering, they also had to get up to speed on electronics and computer programming, as well as music. It helped that most of them were musical: While Brueckner had the sitar skills, Jelliffe sings and Dugan plays the violin.
For the exhibit at Esther M. Klein Art Gallery, the team has set up the robot to play a short improvisation in a melodic form known as the raga kedar, starting with a slow, rhythmic section called the alap and moving into a faster interlude called a jor. In the first part, explains Dugan, the robot will use the rules to pick from a library of semi randomly picked phrases. In the latter part, each note will be randomly chosen. To understand sitar music better, the team consulted with Brueckner’s teacher, Allyn Miner, a senior lecturer in the Department of South Asian studies.
“The biggest compliment,” says Dugan, “was when a sitar player heard it and said, ‘That’s definitely raga kedar.’”
RAVI-Bot will be on display at the Esther M. Klein Art Gallery (215-966-6188) at the University City Science Center, 3600 Market Street, through June 30. You can see a video of RAVI-Bot in action on YouTube at http://www.youtube.com/watch?v=NCPlewIJsL8.
Originally published on April 26, 2007.
