In a lab at the University of Washington, robots are playing air hockey. Or they're solving Rubik's Cubes, mastering chess or painting the next Mona Lisa with a single laser beam. As the robots play, the researchers who built them are learning more about how they work, how they think and where they have room to grow, said Xu Chen, one of those researchers and an associate professor of mechanical engineering at UW. "From a robot's viewpoint, artificial intelligence is getting more and more mature," Chen said, referring to the software and algorithms that help a robot take in its surroundings an...