Planetfall Defense (OEBots) are massive automated attack robots used when tremendous shows of ground force are deemed necessary. About the size of a Magog Swarm Ship, the bots are armed with automatic Gauss guns and large missile launchers.
The Andromeda Ascendant has two OEBots, Tweedle Dee and Tweedle Dum, each possessing articulated necks, and heavy armor. The OEBots are housed in a special hangar, where they can be serviced and re-armed. The bots were first deployed when Andromeda had hundreds of swarm ships latched onto its hull, and they needed to be removed so that no more Magog could board the Andromeda. They obliterated every ship. Their next mission was on Ne'Holland, to gun down snipers who were attempting to assassinate a prince. It was shown they eject shell casings. ("The Prince")
Tweedle-dee and Tweedle-Dum are Planetfall Defense Bots that are stored on Andromeda. It was first used against the Magog on the hull of the Andromeda in space. Andromeda last used them in "The Prince", to defend the prince during coronation.
Similar, though less heavily armed, bots were in one of the hangars first explored by Rev Bem, when he and the others on the salvage team first boarded the Andromeda ("Under the Night"). The ship's Artificial Intelligence used their visual sensors to record th Magog's image, making him the last of the 5 intruders to be located.