$10 Series Elastic Actuator!
Series Elastic Actuators will be showing up in more and more robotics designs meant for public use. For the home hacker they can be very useful as well. Check out the videos below and then start researching robotic arms and walking robots. Chances are they are using SEA's!
Intro and demo video showing the low cost SEA operating.
A more detailed look at the SEA and the components used to build it.
Cool website with an Open SEA design
BADASS 7 degrees of freedom robotic arm using SEA's
Hizook post on the 7 DOF arm with Video!
Design and Analysis of Series Elasticity in Closed-loop Actuator Force Control
Series Elastic Actuators