Fluidic Hardware Strategies for Powering Combined Negative- and Positive-Pressure Artificial Muscles

The performance of pneumatic artificial muscles (PAMs) depends in large part on the fluidic hardware used to add and remove air from their volume. A complete fluidic system usually contains tubing, pneumatic regulators, pneumatic valves, and pneumatic pumps. However, for most PAMs, the performance of the actuator depends on how fast air can be taken into and out of the chamber as the presence of a single chamber entails relatively simple fluidic strategies. In the previous work, a type of PAM called hyperbaric vacuum artificial muscles (Hyper-VAM) which utilizes a negative-pressure inner chamber placed inside a positive-pressure outer chamber has been introduced. Herein, advanced fluidic strategies for this actuator by making use of the pressure equilibrium between these two chambers as the building block for advanced fluidic strategies are investigated. It is shown that it is possible to operate the Hyper-VAM in sub- and hyper-atmospheric conditions during closed-loop actuation and to use the atmosphere as a natural pump starting from a sub- or hyper-atmospheric equilibrium. Herein, these strategies are demonstrated and compared to basic fluidic strategies and fluidic systems capable of implementing cyclic actuation are demonstrated using these strategies.