Building capable robot end effectors, particularly high-complexity hands, can be a daunting challenge.  In this article, we will examine the fabrication of a robot hand with compliant, under-actuated fingers that is rugged enough to bounce back from twisting, end-on and side impacts, falls, collisions, and even severe back-bending.  The specific fabrication process explored is akin to shape deposition manufacturing using materials such as resins (epoxy / Delrin) and urethanes (a "rubbery" substance) of various durometer (hardness).  This particular technique was used to build early hand prototypes for MIT's Nexi (or MDS) robot from the Personal Robotics Group, and further refinements resulted in the Meka Robotics H2 Compliant Hands, as seen on the Simon robot.    Read on for details and pictures -- this should be of interest to robotics hobbyists and professionals alike.

There has been a lot of interest by researchers in compliant hands.  The motivations for simple, compliant robotic hands for manipulation are numerous, and well covered in a recent MIT Tech Review article.  We will examine a design of just such a type of finger, a technique that was ultimately refined to produce the latest Meka Robotics H2 Compliant Hands:

As I mentioned, an early prototype of this hand appeared on the Nexi robot from MIT:

Update 2/8/2010:

At the request of this work's progenitors, much of this article's commentary and multimedia have been removed.   Our apologies -- hopefully the content can be restored at a later date.