Programmable Pressure Amplification Using a Soft Folding Actuator

Fluid powered soft actuators can be interpreted as transmissions between the fluid and mechanical domains. Since volume is rarely directly proportional to extension in these actuator-transmissions, the effective transmission ratio is usually a function of extension. In this paper, we model and experimentally validate a single-chamber device with a mechanical singularity that functions as a continuously variable transmission with a transmission ratio that extends (in theory) between zero and infinity. We harnessed this transmission in a double-chamber device that acts to transform fluid power at an input port to fluid power at an output port through a programmable transmission ratio. In particular, the double-chamber device is capable of pressure amplification. Such a fluidic transmission could be applied to untethered and wearable soft robotic systems in which high pressure sources are not available to meet the requirements of soft actuators under elastic or externally applied loads.