Rogue Robot DLC, Automatron Quest
To get this quest you have to talk to Isabel (The Mechanist is alive) or Ada (The Mechanist is dead) after you take control over the Mechanist facility.
This quest will be triggered or can be aquired when you complete Restoring Order quest.
Related points of interest
Stages of "Rogue Robot" quest
1. Destroy the rogue robot
If The Mechanist is alive:
Isabel has located more of her rogue robots.
If The Mechanist is dead:
Ada has located another one of the Mechanist's robots.
It's very simple, just go to the random location marked on your map and kill all the robots there.
2. Quest completed
This quest is repeatable.