A1: Alexander Moore, a UROP with our group (UROP stands
for Undergraduate Research Opportunity Program), suggested the name Cardea.
He recalled the name Cardea from playing Dungeons and Dragons as a kid.
We did a little poking around the web and found that Cardea is the Roman
goddess of thresholds and door-pivots and thus a patroness of changes-of-state.
Ovid says of Cardea, apparently quoting a religious formula: "Her
power is to open what is shut; to shut what is open."|
A2: Obviously, three arms can do more than two. Imagine needing to hold something that requires two hands while opening a door; three arms would be ideal! Plus there are 3 pairs of arms when one starts with three. On the whole, the goal was to exploit the advantages of humanoid form without being bound to unnecessary restrictions based on the exact form of humans. Thus Cardea won’t have arms that are the same in length, size or end-effectors. Paul Fitzpatrick, a postdoctural lecturer with the group, was the originator of the three arm idea.
A3: In a nutshell, the RMP can dynamically balance on a small wheelbase that is able to support a torso, arms and “head” at a human scale height. Without dynamic balancing, a two wheeled base would have to be much wider than the typical width of a person’s “footprint”.