"A human being may be faster, but you'd have to say 'Thank you,"' said University of Tokyo professor Tomomasa Sato. "That's the best part about a robot. You don't have to feel bad about asking it to do things."

Sato believes Japan, a rapidly aging society where more than a fifth of the population is 65 or older, will lead the world in designing robots to care for the elderly, sick and bedridden.

Already, monitoring technologies, such as sensors that automatically turn on lights when people enter a room, are becoming widespread in Japan.