Characterizing the Peano fluidic muscle and the effects of its geometry properties on its behavior

In this work, we explore the basic static and dynamic behavior of a hydraulically actuated Peano muscle and how its geometry affects key static and dynamic performance metrics. The Peano muscle, or pouch motor is a fluid powered artificial muscle. Similar to McKibben pneumatic artificial muscles (PAMs), it has the ability to generate the high forces of biological muscles with the low threshold pressure of pleated PAMs, but in a slim, easily distributed form. We found that Peano muscles have similar characteristics to other PAMs, but produce lower free-strains. A test rig capable of measuring high-speed flow rates with a Venturi tube revealed that their efficiency peaks at about 40% during highly dynamic movements. Peano muscles with more tubes and of a greater size do not move faster. Also, their muscle tubes should have an aspect ratio of at least 1:3 and channel width greater than 20% to maximize performance. These findings suggest that finite element modeling be used to optimize more complex Peano muscle geometries.