Bobbi No-Nose brought in several workers to dig through the ground to the Diamond City strongroom, as part of the operation. She was looking for a faster way to dig through the ground after her workers were driven out by mirelurks. Luckily, she had managed to get in contact with a mechanic named Mel, who is skilled in robots. He was working on a tunneling robot named Sonya that could quickly dig through loose ground with a powerful sonic pulse.
Imprisoned for a small-time misdemeanor revolving around the robotic waiter Wellingham, Bobbi hired the Sole Survivor to bust Mel out of jail. He brought Sonya along to the Dig to take over from the workers. Her EMP blasts were put into good use for boring through the Boston underground.
Due to the force exerted by Sonya in the strongroom basement, she will be deactivated.
Sonya can be hacked and commanded to follow the player with the appropriate perk.
Her successor, Sonya Mk. II, may be encountered together with Mel as a random encounter in the wasteland after the quest has been completed.
This version is not essential and may already be dead when the player encounters her and Mel. Selecting her corpse in the console, then using recycleactor and moveto player, will cause her to come back to life and resume following Mel.