Robot safety in Hospitals

About ten years ago I worked in a lab building attached to two hospitals and we all shared a common sky-bridge. The hospitals used a robotic mailman to shuttle back and forth between the two hospitals. The robot had an algorithm to turn about 30 degrees when it encountered an object in its path. One day on the bridge, I heard a woman screaming hysterically. She and the robot had somehow gotten into a small three-sided space where she had the robot trapped, and it had her as well. All she had to do was move further into the space and allow the robot to leave, but she was so frightened she wouldn't. We finally had to sort of drag her out.