Quasi-static FEA model for a multi-material soft pneumatic actuator in SOFA

The increasing interest in soft robotics has led to
new designs that exploit the combination of multiple materials,
increasing robustness and enhancing performance. However, the
combination of multiple non-linear materials makes modelling
and eventual control of these highly flexible systems challenging.
This article presents a methodology to model multi-material soft
pneumatic actuators using finite element analysis (FEA), based
on (hyper)elastic constitutive laws fitted on experimental material
characterisation. Modelling in SOFA, a FEA software, allows to
simulate and control in real-time soft robotic structures. One of
the novelties presented in this paper is the development of a new
user-friendly technique for the mesh partitioning in SOFA, using
MATLAB algorithms, that allow the creation of uniform and
more refined meshes and a mesh domain partitioning that can be
adapted for any geometry. As a case study, a cylindrical multimaterial soft pneumatic actuator is considered. It is composed
of an internal chamber, which is constituted of an autonomous
self-healing hydrogel, modelled as a hyperelastic material, and an
external elastic reinforcement, made of thermoplastic polyetherpolyurethane elastomer (TPPU), approached as a linear elastic
material. The simulation of the combination of a hyperelastic and
a linear elastic material in a single design is another contribution
of this work to the scientific literature of SOFA simulations.
Finally, the multi-material model obtained with the new mesh
partitioning technique is simulated in quasi-static conditions and
is experimentally validated, demonstrating an accurate fit between
simulation and reality.

Publication year:2022

Keywords:Soft robotics, multi-material, finite element method, self-healing robots

Accessibility:Open