BALTIMORE (AP) — The Swingobot 2000 was showing off, navigating a busy hallway at Sinai Hospital to scrub the floor. Then Tug, a smaller robot, glided up unexpectedly from behind, returning to the pharmacy after delivering medication to nurses.

Tug was programmed to detect people and other obstacles in its path. It stopped, maneuvered around Swingobot, then continued on its way.

For the Baltimore hospital, and for the robots, too, it was just another day at work.

Before Tug, "we had pharmacy technicians and couriers who would deliver to the floor," said Lisa Polinsky, assistant vice president...