It's striding toward us from the kitchen, smoothly and silently. As I set down my overnight bag and turn to question my friend Jack, it ambles gracefully into the foyer. I can sense Jack watching me out of the corner of his eye, looking for a reaction as his newest purchase stops and stands beside us on two thin mechanical legs and clasps two four-fingered hands behind its back. It's smaller than the average person, lithe, entirely unthreatening–I could take it in a fight. The face isn't human, but it's not the face of an appliance either. And like any good butler, it-he?-humbly bows.
The robotic butler is coming. It's being developed, piece by piece, in university labs and government research centers across the globe. Some scientists are designing dexterous fingers; some are focused on creating sensitive yet rugged artificial skin. Groups in Japan and Germany, at Cornell University and at tiny Olin College in Needham, Massachusetts, are trying to solve the extraordinarily difficult problem of getting a machine to walk efficiently and effectively on two legs. And then there's the matter of building a robot brain, giving a machine the kind of artificial intelligence that allows it to control its limbs and fingers, interact with family and strangers and, perhaps most important, bake a perfect apple pie.
Of course, many top roboticists are motivated by more immediate concerns than the future market for household robo-servants. Cornell engineer Andy Ruina, for example, builds walking robots so he can better understand human locomotion and find a way to assist the elderly when their legs start to fail. But others, like Carnegie Mellon University computer scientist James Kuffner and Olin engineer Gill Pratt, are convinced that the disparate work being done today will eventually converge into a single platform-a machine, Pratt says, that will mow the lawn and rid us of the tedium of housework: a real-life Rosie the Robot. Developing this multitasking, human-shaped machine will require breakthroughs in five key areas: interaction, locomotion, navigation, manipulation and intelligence. Luckily, the past few years have seen an explosion of research and advances in each one.