Combat inhibitor

All robots in Fallout 3, and Fallout: New Vegas have a combat inhibitor located on their back while turrets have a "targeting chip" underneath the barrel.

Function and Advantages to the player character
The combat inhibitor is a device that controls the machine's targeting parameters and allows a robot to determine between friends and foes. Combat inhibitors are very small and are usually located on the back of robots. In the event that the player chooses to cripple the combat inhibitor by targeting it with V.A.T.S., or by accurate free-firing, the robot will go into a frenzy and attack the closest target to it. The player will be notified as if a limb was crippled on an enemy, however you will be notified that the robot "has been frenzied." Crippling a combat inhibitor has the same frenzying effect on robots that crippling an antennae has on a mutant insect.

A frenzied robot will fight until it dies. Frenzying a robot could be a viable way to take out or soften up a group of enemies if they do not see you, or even taking out a group of friendlies without karma loss. However, crippling the combat inhibitor will not affect the robot's attitude toward the player, as shooting a robot anywhere will cause it to become hostile if it was friendly.