Robot Air Muscles - Bio-Inspired Robots Part II

In part one of Bio-Inspired Robots, I started prototyping an air muscle system for my latest project. Not necessarily by choice, I went with a steel braided cable as the muscles exterior. This is fine for high PSI systems (~250psi) and designs that require much more strength and stability; upwards of 200lbs. However, my still-to-be-named project will only weight in around 150lbs in all. So I have opted for a far more pliable, cost effective sheath. I found various sizes and colors of this amazing UV Reactive Expandable Braided Sleeving. For a few bucks this ultra fixable braided sleeve provides all the right properties you want your muscle to exhibit.

One of many important step in assembling your first muscle is to only slightly burn/melt the ends of the sleeve after you snip it down to size. Failure to do so will result in a fully unwound piece of nylon. Lame. So, the first muscle is complete. Fully stretched out it reaches ~11 inches. When contracted at 50psi you get roughly a 2-3" stroke. Very nice.




As for my air source; I made a trip to the local hardware store and bought a $10 portable air pump. 12 volts will work nicely with the rest of the power system. Of course I ripped it apart immediately and found a nice sized-beefy 12 volt dc motor. The motor powers a few step up gears which in turn power the arm that pumps air into the throttle body. A simple elegant design that will ultimately power a 2 gallon 100psi holding tank.