A Study On Soft Material Parameter Determination By Iterative Force-Displacement Curve Fitting

Many soft robots are made of hyperelastic silicone rubbers and usually experience large nonlinear deformations in actions. Accurate material parameters are essential to provide reliable analysis and support robot designs. This letter presents a practical material parameter determination method by iteratively fitting the force-displacement curves measured from two biaxial tension and one uniaxial tension specimens. It reveals the insufficient constraint of one biaxial and one uniaxial test data towards the correct set of material coefficients. Based on three specimens, the material parameter obtained leads to high consistency with the bending validations of four soft fingers, demonstrating the proposed method is capable to accurately determine material properties for hyperelastic soft structures and can be readily used in soft robot designs and analysis.