There is a bug in Fallout New Vegas: often ED-E (the flying drone), your companion is no longer by your side.
In a normal case, it is possible that you have forgotten it. Indeed, ED-E can not follow you in some place (especially in the camp of the legion,...). It can also get stuck in Vault 22 (a defective door ...).
In this case, wait a few days ("T" key: wait) for that ED-E to return toPrimm alone. Note that this also applies to other companions.
But sometimes you can hear the character making comment on the robot, but you can't see it, or just, even after several days, no alert is displayed on a possible return to Primm.
To remedy this ...:
Update your game. Bethesda Softworks has proposed a number of patches.
Open the console with the "square" key
([ID_companion should be replaced with the ID of the partner sought, see Appendix at the bottom of the subject) and then press Enter
Immediately after, without closing the console, type
Transfer the entire inventory, without closing the CONSOLE, then type