Fallout 4 created by Bethesda Game Studios.
Images used for educational purposes only.

- The Robotics Disposal Ground is located in the wilderness to the northwest of Sanctuary, on the side of the road. You’re most likely to find it while travelling to USAF Satellite Station Olivia for a quest.

- The Robotics Disposal Ground is a fairly desolate location. The only items of immediate note from wandering around are a Fusion Cell and a Military-Grade Circuit Board in the trunk near the middle of the Ground; a Fat Man sitting atop several wrecked cars a few hops away from the trunk you just raided; and some Flamer Fuel beside the lamp post. You can also find a Mini Nuke for the Fat Man just outside the Disposal Ground, amid a heap of tires. Look on the other side of the fence from the concrete building.

- Oh, and there’s also an enormous robot. Did I mention the robot? No? Cool.

- Pop into the small concrete building nearby. There’s a first aid kit by the door with some meds inside, two more Military-Grade Circuit Board on the shelves, some crafting items in a toolbox, and a Hot Rodder magazine beside the room’s terminal. Also, a Weapons Workbench.

- Pop onto the terminal. It has some notes of interest, as well as the Combat Sentry Proto MKIV Holotape. You can use the Holotape to activate the Combat Sentry outside, but it won’t do much unless you steal the Holotape for yourself and stick it in your Pip-Boy. This gives you several options:
  • Deactivate the Combat Sentry. Obvious.
  • Engage Defensive Protocol. Doing this will send the Combat Sentry off to wipe out the enemies in one of four nearby compounds, namely USAF Olivia, South Boston Checkpoint, Revere Satellite Array, and Fort Hagan. Very nice if you’re having trouble with any of those areas, though bear in mind that it can’t go inside if there are interior spots, such as at USAF Olivia. Still, handy - especially since the thing will return to the Disposal Ground between missions. 
  • Trigger a self-destruct. This will destroy the Combat Sentry (obviously) and allow you to scrounge it for parts, including two Fusion Cores, 40 5.56 Rounds, a Biometric Scanner, two Enhanced Targeting Cards, a Fuse, and four pieces of Aluminum. The explosion is enough to kill you, so make sure you clear out. (It will also explode like this if you blow it up the old-fashioned way, so watch out.)
(I’ve heard conflicting reports as to how effective the Cmbat Sentry is at helping you. It seems a bit glitchy to me, too. Still, worth a try? At the very least it doesn’t seem inclined to go to areas you’ve already cleared. And if it does glitch for you and do nothing, well... blow it up. Its parts are pretty great.)