Interacting Fluidic Hysterons

Inflatable structures exploit nonlinearities in the pressure-volume domain to achieve remarkable functionalities, like sequencing and energy release. More complex behaviors emerge when inflatable structures with rich characteristics are combined in a fluidic network, where interactions between nonlinearities dictate the function on the system level. While the serial connection of such structures has been extensively studied, a generalization that includes parallel connections remains elusive. In this research, we establish the fundamentals of serial and parallel connected inflatables with arbitrary nonlinearities and apply it to the pressure-loaded inflation of fluidic hysterons in parallel. We make use of a reduced order model of a fluidic hysteron to analyze its behavior during interaction, and introduce pre-loading to shape the stable paths in state-space. We experimentally validate this model via a parallel system comprising two bistable membranes and report good correspondence between both. These results not only demonstrate how the interaction between the membranes influences the overall system's switching behavior, but also give a tuning knob via preloading that can be used to alter this switching behavior, paving the way for more efficient design of soft robotic applications.