When US armed forces finally took interest in automated ground forces, they first tested it as nothing more than recon and quick close air support units that can barely hit the target. But when the civilian unrest has reached it peek, due to many American Soldiers lives lost in conflicts out side of their homeland, the Congress and the Pentagon has forced the US Army to adapt Drones to their doctrines. It wasn't so long when the US Forces started to acquire contractors to purposely build unmanned combat vehicles. Preliminary, these contracts were just to upgrade the current unmanned vehicles, that was until they started sending design plans to Pentagon Engineers and started the new age drone warfare. One of the first designs were the Rottweiler Drone series which concept were highly favored the Army and Marine Corps. When the Armored Corps requested drone concepts for their tanks hundreds flood in, however only three took the spot. One, designed by a recent graduate in engineering, and a major in robotics, a simple hover drone compact enough to hold an electric motor, stable gyroscope and run on motorcycle battery. Pentagon engineers bought, revised this concept and released an upgraded variant which includes a shortened .30 cal machine gun and mini-repair equipment. First tested on light vehicles deployed in Afghanistan, the repair rate of the drones were so effective every dent and holes were patch up in minutes and as if it was recently out of the factory, which made field engineers redundant, forcing most of them to resign/retire or be transferred to maintenance crews.
When the Global War on Terror finally escalated, the drones were finally applied to full effect and to all US ground vehicles. However the drone operator inside the vehicle abused the effectiveness of the machine guns of drones which costed the drones being fired upon by RPG equipped rebels and Stinger sites, instead of repairing the parent vehicles. Upon initiating operation zero hour and Congress revisions, most if not all of US Forces Doctrines are forced to adopt drone warfare, this was decided as solution to the staggering amount lost of grunts and vehicles in the war, minimize casualties as possible.
Upon Griffon's orders, the battle drones are now by default have an AI programed in them, set to stay near to their parent vehicle, and self repair systems reducing the chances they are shot down and the need for an extra crew member for a ground vehicle.
A larger and heavily armed variant of the battle drone have made it's way on the Air Force General's ground troops, controlled as a hive in a Stryker IAV.
An upgrade unit exclusive to all US Combat vehicles, it's main purpose is repair and protect it's parent vehicle from infantry targets. While it's repair rate is moderate, it's capability to protect it's parent vehicle is invaluable as any infantry too foolish enough will get eliminated.
Should you not be satisfied with the infantry defense the Microwave Tank and WASP Drone Carrier, and the repair rate of the Repair Drone. Then the battle drone will probably answer your problems, while not specialized than the three aforementioned. They do came in handy when on the direct action, as the Microwave and WASP Drone Carrier when targeting enemy units cannot deal with infantry and the Repair Drone's repair effect is not that large enough to cover most of your units and they need to be upgraded to repair ground vehicles.
Nothing more than a nuisance, they can be only eliminated if their parent vehicle is eliminated. Their range is also limited as they cannot leave their parent vehicle, this can also further be limited when they are repairing. The only threat they posses is against infantry, so garrison your men when possible.