Numerical Simulation of an Untethered Omni-Directional Star-Shaped Swimming Robot

Simulating the swimming of soft underwater robot remains challenging due to the absence of an efficient numerical framework that can effectively capture the geometrically nonlinear deformation of soft materials and structures when interacting with a liquid environment. Here, we address this by introducing a discrete differential geometry-based model that incorporates an implicit treatment of the elasticity of soft limbs and a fluid model with three different components: hydrodynamic drag, jetting, and virtual added mass. The physical engine can run faster than real-time on a single thread desktop processor. We experimentally validate this numerical simulation tool by performing tests using an untethered omnidirectional star-shaped swimming soft robot that is capable of moving with multiple swimming gaits. Quantitative agreement between experiment and simulation indicates the potential application of such a numerical framework for robot design and for model-based control schemes.