GRASP robot throws out first pitch at Phillies game

On Wednesday, April 20, a special member of the Penn community took to the field at Citizens Bank Park as the Phillies met the Milwaukee Brewers. A robot from the University’s General Robotics, Automation, Sensing and Perception (GRASP) Lab threw out the first pitch as part of the Phillies’ “Science Day at the Ballpark.” The event was part of the citywide Philadelphia Science Festival, which runs April 15 through 28.

The pitching robot is the creation of Vijay Kumar, deputy dean of education in the School of Engineering and Applied Science, and his collaborators in the Department of Mechanical Engineering and Applied Mechanics: staff members Jamie Gewirtz and Jordan Brindza, as well as graduate student Christian Moore.

The idea for the robot came from Gerri Trooksin, the director of the Science Festival, and Rebecca Stein, the associate director for research and educational outreach at Penn Engineering.

Comprised of systems that GRASP team members are using in their ongoing research, the robot has an arm that is made by Barrett Technology and is designed to replicate smooth, fluid motion. When the robot is not throwing fastballs, the GRASP lab researchers are teaching it to operate in common human situations that require a certain amount of dexterity and control, such as locating and opening a door handle.

Getting the robot ready for the “the big show” was a challenge. Because its arm is built with a failsafe that prevents it from moving too fast and damaging its internal mechanisms, the Penn team had to innovate in order to get its pitches up to major league speed and distance. To do so, they replaced the arm’s rotating wrist and three-fingered hand with a piston-driven scoop.

The team modeled the robot’s custom scoop on a toy jai-alai cesta, fashioning it out of carbon fiber to reduce its weight. After programming the arm’s throwing motion, they plotted the ideal release point for the ball. When the arm reaches that point, the piston on the wrist fires, causing the scoop to snap forward and deliver the pitch.

“You know what they say, it’s all in the wrist,” says Kumar.

The robot was also outfitted with a motion-tracking camera “head” that could be used to locate the strike zone on a given batter, though it only tossed to the Phillie Phanatic. The robot was rolled onto the field atop a modified Segway platform.

Before and during the game, science-minded Phillies fans were also treated to a number of other Science Day activities and demonstrations set up in booths along the concourse.

Originally published on April 14, 2011