These are droids placed on various maps by the designers of the map. Unlike the Probe Droid, which is player-controlled, and the other droids, which are deployed by players and then follows them around, these droids are stationary.
Gonk[]
The Gonk, essentially a box on two legs in appearance, is charged with replenishing the ammunition of nearby infantry and vehicles.
Medical Droid[]
The Medical Droid heals wounded soldiers near it.
WED Droid[]
The WED Droid takes care of repairs of nearby vehicles. Currently, players can find it in the Alliance hangar on Ryloth.