You'll never see them, but 28 robots move about the halls of Cedars-Sinai 24 hours a day.

The 1,000-pound vehicles use their own elevators, hallways, and floors to move through the hospital towers, carrying up to 20 tons of surgery supplies, linens, food, and waste every day.

The paths of the robots are programmed to keep them out of the way of human workers as much as possible, but they're also built to interact with humans safely when necessary.

"Each unit is equipped with an array of sensors which allow it to safely navigate through the facility," says Robert Anchondo, the service technician who spends his days programming and maintaining the robots. "This includes emergency stop buttons, flashing alarm and turn signal lights, front and rear motion sensors, and even a warning voice synthesizer."

Watch the video above to see the robots in action.