Interacting Parallel Fluidic Hysterons

Structures exhibiting highly nonlinear behavior are essential for realizing advanced functionality without software; however, their nonlinearity gives rise to complex and difficult-to-predict interactions. Among these nonlinear structures, fluidic hysterons - nonlinear fluidic elements that retain memory - stand out as particularly promising for realizing complex behaviors in inflatable soft systems. To date, inflatable hysteretic elements have been almost exclusively coupled in pressure-shared configurations, corresponding to a series connection in an energetic sense. Here, a complementary equal-volume-change architecture is studied, in which inflatable hysterons are coupled in parallel. This study examines the principles governing how nonlinear inflatable structures, such as fluidic hysterons, behave when connected in pressure-volume space. A general framework is developed to describe both series and parallel connections, and a practical strategy based on presetting pressures and volumes is introduced to alter the interactions. Experiments on parallel-connected fluidic hysterons validate the analytical predictions and demonstrate how preset volume provides a practical control parameter for tuning interaction strength and functional response. These results establish volume-constrained parallel coupling as a new design principle for inflatable systems with distributed memory and embodied computation.