SAN FRANCISCO -- Sidney Chen and his daughter, Elizabeth, were watching a robot designed by kids from local high schools throw Frisbees through a wooden goal. A little bit earlier, Cathy Markhefka's children got to play with Linkbot, a robot that you can drive by just tilting a remote control forward and back or side to side. And Robert Liebsch's son, Thomas, was being chased by a small robot programmed to follow the green ball he was holding.

"It's pretty awesome," Liebsch said.

He and the other parents and their kids were just some of the many Bay Area residents who got a close-up look at locally designed cutting-edge robots on Saturday at AT&T Park. They were among the 30,000 attendees of Discovery Days, the closing event of the third annual Bay Area Science Festival.

Artie, 4, (parents declined to use last name), left, designs a social robot form the Tech Museum of Innovation at the Bay Area Science Festival at AT&T
Artie, 4, (parents declined to use last name), left, designs a social robot form the Tech Museum of Innovation at the Bay Area Science Festival at AT&T Park in San Francisco, Calif. on Sat., Nov. 2, 2013. The social robots premiered at the Tech Museum of Innovation over the summer and allowed kids to design robots with personalities and specific themes such as "treat a patient' or "save a city." (LiPo Ching/Bay Area News Group) ( LiPo Ching )

The robots certainly weren't the only attraction at Saturday's event, which featured more than 150 exhibitors. Inside the ballpark, kids could do everything from touch a dissected squid to build a microscope out of Legos to view a 3D printer in action.

But the placement of the robot "zoo" in Willie Mays Plaza, the park's main entrance, made it hard to miss.

Elizabeth Chen, for one, seemed excited to see the Frisbee-throwing robots.

"I'm really interested in creating stuff," said Elizabeth, 10, whose family lives in Menlo Park. "I'm interested in how robots are programmed."

The event represented an opportunity for local robot makers to show off their latest bots. Attendees could find everything from $30,000 child-sized robots designed to stack things on store or warehouse shelves to robots that were only1-inch cubed that were programmed to push other so-called nanobots out of a hand-sized "sumo" ring.

"We're here to show off the robot and get children engaged," said Melonee Wise, CEO of Unbounded Robotics, which designed the shelf-stocking robot called UBR-1. "We want to show how fun (robotics) could be."

Unbounded Robotics is a spin-off of Willow Garage, a Menlo Park-based company trying to spur the development of the robotics industry. The UBR-1 runs ROS, the robotic operating system developed at Willow Garage.

Although the robot costs as much as a new car, its price is actually about a tenth of what Willow Garage charges for its PR2 robot, Wise said. Unbounded plans to sell it to researchers and to companies.

There are many people in the robotics research community who are "desperate for this robot," she said. "I have so many who call me and say, 'I want it now.' "

On the other end of the robotic scale from the UBR-1 was Bill Weiler's1-inch cube, ButterBot. Weiler, a San Jose resident, developed the robot to participate in the nanobot sumo event at the RoboGames competition last April. It took him about a month and cost just $300 in parts and tools to design the first one. Weiler, a firmware engineer at flash storage company OCZ by day, designed the robot at home at night in his spare time.

Weiler hopes to build a business around the ButterBot eventually, but he was at the festival Saturday mostly for fun, to share his invention with others in the community, particularly children.

"Kids," he said, "are the best."

Elsewhere out on the plaza, Lindsay's Alsadir's two kids were playing tic-tac-toe using a robot to place their game pieces on an improvised vertical game board made up of crossed PVC pipes. Alsadir, of Pescadero, said she was surprised at how much her children were enjoying it.

She said she had wanted to attend the festival last year but wasn't able to come. So she made a point of taking her kids this year.

"I wanted to introduce science into my children's imagination," she said. "It's important to come."

Not to mention, fun.

Contact Troy Wolverton at 408-840-4285. Follow him at Twitter.com/troywolv.