A Guard robot is a type of automaton used by the Orb Alliance. Their function is to protect restricted areas and prohibit entry, or execute those who violate.
They are controlled by the Alliance Computer and orders come from the Empire State Building. Guard robots are stationed in Bellevue Hospital around the food processing center. Robots at the Hospital can be set either to patrol the hallways or to stay on assigned positions, and either to stay in rooms or follow important Orbs.
When Anna Osborne broke into a wall, she was unable to proceed due to such a robot, as it was set to stay to its assigned position.
When the Manhunter turned sides, he rearranged the security orders and returned to the hospital. An Orb spotted him and a robot (patrolling the hall) captured and threw him into a room with a large pile of human bones. The Manhunter reached a screened window looking down into a room where an Orb and a couple of robots rendered human corpses into food. As soon as an Orb left, the guard robot followed it, and room emptied, allowing him to escape.