The robotics pioneer who helped unleash the Roomba vacuum is now betting that you might one day replace your beloved dog or cat with a plush robot that follows you around your home and adapts to your daily habits. Colin Angle unveiled a four-legged prototype of that artificial pet, called a Familiar, on Monday. Imagine a creature the size of a bulldog with doe-like eyes and bear cub ears and paws, extending itself into a greeting stretch that invites you to pat its touch-sensitive fake fur. The lifelike machine, powered by the latest artificial intelligence technology, would not have been possible when Angle co-founded iRobot in 1990.