FONS: a Python framework for simulating nonlinear inflatable actuator networks

Soft robots designed within a conventional robotic framework typically consist of individually addressable compliant actuators that are merged together into a deformable body. For inflatable soft robots, this comes at a high cost of tethering which drastically limits their autonomy and versatility. This cost can be decreased by connecting multiple actuators in a fluidic network and partially offloading control to the passive interactions within the network. This type of morphological control necessitates some of the elements in the network to have nonlinear characteristics. However a standardized simulation framework for such networks is lacking. Here, we introduce the open-source python library FONS (Fluidic object-oriented network simulator), a tool for simulating fluidic interactions in lumped fluidic networks of arbitrary size. It is compatible with both gaseous and liquid fluids and supports analytical, simulated and measured characteristics for all components. These components can be defined using a library of standard components or can be implemented as custom objects following a modular object-oriented framework. We show that FONS is capable of simulating a multitude of systems with highly non-linear components exhibiting morphological control.