An omnidirectional unmanned ground vehicle (UGV)is able to move in any planar direction regardless of itscurrent pose. To date, nearly all designs and analyses ofomnidirectional robots have considered the case ofmotion on flat, smooth terrain. This paper presents thedesign, analysis, and prototype development of a manportable omnidirectional UGV designed for operation inrough terrain. Design guidelines are presented that arederived from geometric constraints on wheel and linkagesizes. The effects of terrain roughness and loss of wheelcontact on UGV mobility are also analyzed.Aframework for UGV design optimization is presented thatconsiders vehicle kinematic isotropy, wheel-terraininteraction properties, predicted obstacle traversability,and maximum traversable distance over various outdoorterrain types. The results are used to design two small(i.e. 1m characteristic length), lightweight (i.e.approximately 25 kg) UGV prototypes.