Student builds robot rocker

Vision sensors have given robots an eye for music. Pete Nikrin, an engineering student at Minnesota West Community and Technical College, was tired of hearing his friend gloat about his high scores for the Guitar Hero video game. Determined to knock him down a peg, Nikrin developed an amazingly accurate Guitar Hero-playing robot. A PresencePLUS P4 OMNI vision sensor with a right-angle lens from Banner Engineering allows the robot to respond to each note as it appears onscreen.

Starting with a mannequin, Nikrin installed the camera lens as the robot’s left eye, which would be positioned toward the TV screen. The robot, named Roxanne, identified the notes to be played by using an Edge vision tool, which detects, counts and locates the transition between bright and dark pixels in an image area. “We set-up five Edge tools that ran horizontally across the screen, one for every fret, and positioned the tools to focus on the notes at the bottom of each,” Nikrin explained in an official press release. “The Edge tools sent a constant signal as the five vertical fret lines progressed, and when a bright white dot appeared in the middle of a dark colored circle, the Edge tool allowed the sensor detect it.”

Nikrin worked with Jeff Curtis, the Senior Applications Engineer at Banner, to guarantee the robot operated consistently and accurately within a range of lighting conditions and orientations. “We honed a Locate tool and gave it a fixed point—a piece of reflective tape on the PC monitor—to focus on,” Curtis said. “This ensures the Edge tools are in the proper location to detect each note as it comes along and allows for any slight vibration in the application environment that could result in some deviation. If the robot starts to sag a bit, for example, it can still play.”

Using this sensor technology, Roxanne has, on Medium mode, hit 100 percent accuracy at times, and it averaged 98 percent accuracy during the remainder of Nikrin’s tenure at Minnesota West. She could achieve up to 95 percent accuracy on Hard mode and 80 percent accuracy on Expert mode, due to the increased mechanical requirements of the robot’s fingers. Today, Roxanne still challenges Minnesota West engineering students in regular rock sessions. Nikrin may have succeeded in getting Roxanne’s skills up to rock star standards, but she’s going to need to work on her stage presence before she goes on tour.