The robot revolution has long sounded like a far-off sci-fi notion, but it’s a reality at the e-commerce giant.

Amazon's expanding fleet of robots includes: Hercules, a lifter capable of handling 1,250 pounds; Pegasus, which sorts packages on conveyor belts; and Proteus, the company's first fully autonomous robot able to operate directly alongside people.

Amazon is close to having more robots operating inside its warehouses than humans after the e-commerce giant announced this week that it now has more than a million robots working at its facilities around the world.