This model is called Oberon Droid because  of the robot characteristics as the
protector of mankind. Oberon are stands for king or leader. The origin name of 
that term is from medieval folklore. The Oberon Droid looks powerful enough 
to carry the world on its shoulder , much like its mythological forebear.     

The basic shape for this model come from the structure from the mentol bulb. 
The reason this shape is chosen because light bulb can represent light and good.
Based on psychological term the circle/oval shape tend to send a positive 
emotional message of harmony and protection. Besides that, circles have a free 
sense of movement. Their movement may also represent power and energy.

Oberon Droid