The Sentinel Control System, also known as Sentinel Power Armor or Sentinels, are a type of robot encountered in the Commonwealth. It is available in the Fallout 4 Creation Club creation Sentinel Control System Companion.
The Sentinel Control System was developed in cooperation by West Tek and General Atomics International prior to the Great War. It served as an experimental system developed to supplement normal military deployments by utilizing existing Power Armor units. After the Great War, the technology was recovered by the Brotherhood of Steel, utilized in experiments focusing on fully unmanned missions. They were previously utilized by the Brotherhood Outcasts, of which the paint can still be seen.
The first experiment utilized a Sentinel unit with AI tuned for advanced friend/foe discrimination, as well as threat elimination drive. The mission attempted to test human interaction and reception of a commanding personality matrix by patrolling a 0.5 mile radius and performing routine peacekeeping operations. The result was not successful as the AI turned hostile towards nearby persons, and a remote shutdown was not possible, requiring manual decommission.
Three units supplemented a group of Brotherhood soldiers in Sector 11 of the Commonwealth for a 23 day long mission, charged with escorting Knight Maria Harper and Scribes Dawson and Vasquez. However, Dawson hacked into Maria and Vasquez' units and had all three ambush the two soldiers.
Sentinels appear as ordinary Power Armor frames and are able to equip any pieces of Power Armor. The majority of sentinel Power Armors are hostile and will attack on sight. The sole exception is Dawson's suit, which the Sole Survivor can hack into with the Pip-Boy 3000 Mark IV, after killing him and acquiring his passcode.
While plugged into the sentinel, it is possible to modify its loadout, switch between standby and escort mode, or change its personality matrix between that of a Sentry Bot, Mister Gutsy, Assaultron, or "memory free" mode. One is also able to get a Liberty Prime personality matrix in a miscellaneous objective triggered by reading the entirety of Dawson's holotape. The sentinel does not take up a companion slot while following the player character.
- Two hostile sentinels are standing at an intersection, guarding the bodies of Maria and Vasquez, west of Lexington.
- An inactive unit is at the Schoelt Propane Station. It can be hacked into and made a companion following the death of Dawson.
- After the completion of Malevolent Malfunction, a hostile, rogue unit can be found and killed at Relay tower 0BB-915. This unit is unique in having the Liberty Prime voice as default as opposed to the Sentry Bot voices of the others, and carries a minigun instead of a laser rifle.
- The sentinel companion will turn on its helmet's headlamp at night, no matter whether it is in escort or standby mode. It will turn off the headlamp while sneaking.
- Unlike other companions, the sentinel companion can accidentally deal damage to the player character even if they have the Inspirational perk. It is therefore advised that one avoids shootouts in close quarters with the sentinel, and even perhaps avoids arming the sentinel with high-damaging weapons.
- Power Armor equipped on the sentinel companion will never break for as long as the sentinel is wearing it (although the sentinel companion itself can still be temporarily downed like a true companion). Builds that utilize low-durability Power Armor such as Tessa's Fist or the Overboss Power Armor are thus much more viable on the sentinel.
- It is important to note that, where ammo and weapons are concerned, the sentinel companion functions like a human or synth companion, such as Preston or Danse, instead of like robotic companions such as Codsworth or Ada. Which is to say, it can be equipped with any weapon, but it cannot fire said weapon unless it is also given the pertinent ammo type, but if it runs out of ammo it will switch to its default weapon (in this case a laser rifle) for which it has unlimited ammo.
- This Creation Club content seems particularly prone to mod conflicts, and works up to the very end, but at that point the game fails to apply the hidden perk needed to actually hack the armor. This can be resolved on PC by opening the console and running
help "power armor hack" 4to obtain the object ID of the perk, and then manually adding it via the console command
player.addperk xwhere x is the object ID of the perk.
- If one happens to get the personality matrix for Liberty Prime before getting the optional quest, the game will forever show an objective marker over the player marker in the map. To force the quest to complete, one can use console commands. The quest id can be found by using
help OptionalVoiceQuest. Then the quest can be forced to complete by using
completeallobjectives xwhere x is the quest ID.