The Separatists preparations for the Clone Wars involved the production of many new war machines to augment the Droid forces.
As part of this development the Separatists experimented with various forms of armoured assault tanks. The key roll of these vehicles was to deliver heavy fire power to the battle field in support of infantry droids.
This variant of the AAT was never put into full production. It was found in trials that the hovering platform was not stable enough to deliver acurate repetative fire. The main multi-melta cannon was a success and went on to be mounted on other vehicles.
The vehicle hold two droids, a commander and a pilot.
This model was inspired by a concept drawing in the 'The art of Star Wars - Episode I'.