Minneapolis, MN — Banner Engineering Corp. partnered with a Minnesota West Community and Technical College engineering student and robotics instructor to develop a robot designed to play the Guitar Hero® video game—responding to each note as it appears onscreen. Pete Nikrin, who graduated from Minnesota West in 2008 and now works as a manufacturing engineer at Meier Tool & Engineering, designed the robot to compete with a friend that Nikrin had introduced to the game and, after playing for two weeks, had surpassed Nikrin in his ability.
Bill Manor, robotics instructor at Minnesota West, suggested Nikrin incorporate a PresencePLUS® P4 OMNI vision sensor with a right-angle lens from Banner Engineering. Manor had such a vision system in his possession, as Minnesota West had purchased it at a discount through Banner as a start-up education kit.
“Students have used Banner vision sensors in many projects over the years—to inspect containers, for example, as they come down a conveyor,” Manor said.
To develop his Guitar Hero robot, Nikrin used a mannequin—complete with Minnesota West sweatshirt, hat and painted fingernails—and installed the camera lens as the robot’s left eye, which would be positioned toward the TV or computer 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.
Roxanne plays Guitar Hero® using Banner vision sensor
“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 said. “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.”
Jeff Curtis, Senior Applications Engineer at Banner, worked with Nikrin and Manor to ensure the robot’s processing time was fast enough to keep up with the video game. Once a note was identified, communicating this signal efficiently depended upon a heavy amount of programming, as well as Ethernet technology applied through a Modbus register. A PLC was programmed so that it constantly looked at the vision sensor’s register. Once the Edge tool senses a note, the PLC notices the change in the register, and the logic in the PLC fires a solenoid that activates the robot’s finger. Just as a human player would react, the robot’s finger then presses down on the appropriate note on the guitar. This set-up resulted in 9 ms processing speed.
To ensure consistent, accurate operation, the team needed to ensure Roxanne could play within a range of lighting conditions—as she would be relocated from classrooms to gymnasiums for demonstrations—as well as confirm the robot was correctly oriented with the monitor displaying the video game. They solved this problem by using a Locate tool, an edge-based vision tool that finds the absolute or relative position of the target in an image by finding its first edge.
PresencePLUS® P4 OMNI
“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 technique, 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 required. Today, Roxanne still engages current and prospective Minnesota West engineering students, and Nikrin looks back on it with both a sense of accomplishment and a hefty dose of gratitude.
“Throughout the process, I was impressed with Banner’s dedication to their products and customers,” he added. “Bill and I both thought that they went above and beyond to help with a school project, which might seem trivial to some companies.”